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Volume 95-B, Issue SUPP_15 March 2013 International Society for Technology in Arthroplasty (ISTA) 2012 Annual Congress

Ahmed Al Mandhari Omid Alizadehkhaiyat Chrysanthos Chrysanthou Simon Frostick

Background

The procedures of total elbow and shoulder replacements increased 6% to 13% annually from 1993 to 2007 with revision-related burden increasing from 4.5% to 7%. The revisions of the shoulder and elbow prostheses due to aseptic loosening, periprosthetic fractures, infections have led to the use of standard or custom-made implants due to significant bone loss. This study reports our experience in the management of complicated primary and revisions of total shoulder and elbow replacements with significant humeral bone loss and in metabolic diseases of the elbow and shoulder treated with bone resection using The Mosaic Humeral Replacement System.

Patients and Materials

A total of 20 patients underwent total elbow or shoulder arthroplasty using the Mosaic Humeral Replacement System (Biomet, UK). The Mosaic system was used in 8 shoulder arthroplasties (Group A) and in 12 elbow arthroplasties (Group B). The underlying pathologis in Group A included 2 malunited proximal humerus fracture, 1 humeral osteomyelitis, 1 shoulder chondrosarcoma, 1 aggressive Gigantic Cell Tumor with prosthetic fracture, 2 metastatic lytic lesion, and 1 failed fixation of non-union proximal humerus. Figure 1 shows Mosaic implant after complex fracture of proximal humerus. Reasons for Mosaic arthroplasty in Group B included 3 humeral component revisions due to periprosthetic fracture, 1 prosthesis breaking-up with fractures, 1 revision of loose Souter Strathclyde prosthesis, 1 loose prosthesis due to infection, 1 highly comminuted elbow fracture, 1 aseptic loosening of humeral component of total elbow replacement, 3 revision of total elbow replacement due loosening and 1 pathological distal humerus fracture due to metastasis. Figure 2&3 shows pre- and post-operative Mosaic implant following complex periprosthetic fracture of distal humerus.


Omid Alizadehkhaiyat Karthik Vishwanathan Simon Frostick Ahmed Al Mandhari

Background

The quest for the perfectly designed elbow prosthesis continues as instability and loosening remain the foremost reasons for the failure of total elbow replacement (TER). The Discovery® Elbow System (Biomet, UK) (Figure 1), which has been used in UK since 2003, is one of the latest generations of linked prosthesis. This system was designed to decrease polyethylene-bushing wear, improve anatomic stem design, restore elbow joint biomechanics, and produce a hinge that could be easily revised. This report describes the short term outcome of TER using the Discovery® Elbow System.

Patients and Methods

A total of 60 TERs including 48 primary and 12 revisions were performed between 2003 and 2008. Patients included 21 males (37%) and 36 females (63%) with a mean age of 63 years. The indications for primary TER were advanced rheumatoid arthritis (n=19), osteoarthritis (n=16), post traumatic osteoarthritis (n=9), acute fractures (n=3), and haemophilic arthropathy (n=1). The outcome was assessed using pain score, Liverpool Elbow Score (LES), and range of movement during a mean follow-up of 26 months. Associated complications were documented. Radiological assessment included evaluation for loosening, instability and periprosthetic fractures.


Omid Alizadehkhaiyat Alexandros Kyriakos Amanda Williams Simon Frostick Ahmed Al Mandhari

BACKGROUND

Reverse total shoulder arthroplasty (RTSA) provides an alternative to standard total shoulder arthroplasty in the treatment of selected complex shoulder problems including failed shoulder replacements. The purpose of this report is to present outcome of RTSA using Comprehensive Reverse System (CRS) as either primary or revision treatment choice.

PATIENTS AND MATERIALS

Between September 2010 and April 2012, 54 patients (36 females, 18 males) with the mean age of 68.4 (±10) underwent RTSA-CRS. In 27 patients RTSA-CRS was performed as a revision due to failed previous arthroplasty. Primary underlying conditions included AVN (2), massive irreparable rotator cuff tear (2), primary osteoarthritis (7), post-traumatic osteoarthritis (2), rheumatoid arthritis (6), and rotator cuff arthropathy (8). It was not possible to complete the operation in 6 patients (4 revisions group 2 AVN cases) due to substantial glenoid erosion. Preoperative CT scan was performed in 50% of patients to assess the bony stock of the glenoid. In some patients ultrasound and MRI were performed to acquire additional information. A total of 46 patients were followed-up by means of antroposterior and axial plain X-rays, pain and satisfaction level (VAS/0–10), stiffness, Constant Score, Oxford Shoulder Score, SF-12 (Physical and mental Subscales), and range of movement for a mean duration of 6.5 months (±4.2).


Shahram Amiri Bassam Masri Donald Garbuz Carolyn Anglin David Wilson

INTRODUCTION

Poor acetabular cup orientation in total hip arthroplasty (THA) can cause dislocation and impingement, and lead to osteolysis (Little et al., 2009) and inflammatory soft tissue reactions (Haan et al., 2008). While the intrinsic accuracy of cup positioning in navigation is reported as low as 1° (Parratte et al., 2009), a large anterior pelvic tilt may lead to an offset of the same magnitude in the final cup anteversion (Wolf et al., 2005). The objectives of this study are to demonstrate feasibility of a new, non-invasive radiographic tool for accurate preoperative determination of a patient's specific pelvis angle, and intraoperative and postoperative assessment of the acetabular cup orientation with respect to boney landmarks.

METHODS

The methodology stitches multiple radiographic views around the pelvis using a multi-planar radiography setup (Amiri et al., 2011) and reconstructs the reference boney landmarks and the acetabular cup in three dimensions using previously developed algorithms and software (Amiri et al., 2012). To validate the methodology, a Sawbone model of the pelvis and femur was implanted with a standard cementless metal-on-polyethylene THA, and was tracked and digitized by an Optotrak motion tracking system. Five radiographic views were acquired at the pubic tubercle (PT) and anterior-superior iliac spine (ASIS) levels (Views 1 to 5 in Fig 1). Imaging and analysis were repeated 10 times. Custom software (Joint 3D) was used to reconstruct the right and left PT and ASIS by fitting spheres to the corresponding pairs of images (Fig 1). The three-dimensional pose of the acetabular cup was reconstructed in the software by solving a back-projection equation of the elliptical shadow of the cup opening. Accuracies were measured as mean differences from the digitized references. A sample of the reconstructed graphical output for the anterior pelvic plane (APP) and the cup, in comparison to the digitized reference, is shown in Fig 2. Repeatability was estimated as standard deviation of the measures for the reconstructed locations of the boney landmarks and the APP (known as a standard reference plane for cup placement).


Takashi Atsumi Satoshi Tamaoki Ryosuke Nakanishi Minoru Watanabe Toshihisa Kajiwara

Treatment of the femoral head necrosis with severe extensive collapse in young adults and adolescents are still challenging. We thought preserve the joint and bone stock were important factor for the treatment of femoral head necrosis in young patients. We reviewed the posterior rotational osteotomy for younger patients with severe osteonecrosis. The advantages of posterior rotational osteotomy are; the necrotic area is moved to non-weight bearing portion. The posterior column artery is shifted medially without vascular damage by rotation. Postoperative uncollapsed anterior viable areas are moved to the loaded portion below the acetabular roof in flexed positions. Eighty five hips of 66 young adults (less than 50 years old, mean age; 31 years) with extensive necrosis treated by posterior rotational osteotomy were reviewed with more than 5 year follow up with a mean of 9 years. Results of 13 hips of 12 adolescents (mean age; 14 years) with extensive collapsed necrosis treated by this procedure were also studied with a mean of 6.5 years. A mean degree of posterior rotation was 121. Recollapse was prevented in 77 hips (91%) of adults, and all 13 hips of adolescents on final AP radiographs. Collapsed lesion was remodeled well and resphericity of the postoperative transferred medial collapsed femoral head on final AP radiographs was observed. However, some of the cases were out of indication of the joint preserving procedure showing extensive lesion. In these cases, we performed the MAYO conservative stem for preserving bone stock. Radiological results of 26 hips with osteonecrosis treated by MAYO stem (mean age 42 years, minimum 5 year follow-up. mean; 6.7 years) showed that 2 mm subsidence in one, osteointegration of zone 2, 6 in 93%, no entire lucent line. No hips were revised for late loosening associated with osteolysis. CT imaging indicated that spot welds of zone 2, 6 were found in 100ï¼ï¿½, stress shielding of zone 1, 5 (23.5ï¼ï¿½). These operations were useful particularly for younger patients.


Michael B. Cross Greg Klingenstein Christopher Plaskos Denis Nam Angela Li Andrew Pearle David J. Mayman

Introduction

The aim of this study was to quantitatively analyze the amount coronal plane laxity in mid-flexion that occurs with a loose extension gap in TKA. In the setting of a loose extension gap, we hypothesized that although full extension is achieved, a loose extension gap will ultimately lead to increased varus and/or valgus laxity throughout mid flexion.

Methods

After obtaining IRB approval, six fresh-frozen cadaver legs from hip-to-toe underwent TKA with a posterior stabilized implant (APEX PS OMNIlife Science, Inc.) using a computer navigation system equipped with a robotic cutting-guide, in this controlled laboratory cadaveric study. After the initial tibial and femoral resections were performed, and the flexion and extension gaps were balanced using navigation, a 4 mm distal recut was made in the distal femur to create a loose extension gap (using the same thickness of polyethylene as the well-balanced case). Real implants were used in the study to eliminate error in any laxity inherent to the trials. The navigation system was used to measure overall coronal plane laxity by measuring the mechanical alignment angle at maximum extension, 30, 45, 60 and 90 degrees of flexion, when applying a standardized varus/valgus load of 9.8 [Nm] across the knee using a 4 kg spring-load located at 25 cm distal to the knee joint line. (Figure 1). Coronal plane laxity was defined as the absolute difference (in degrees) between the mean mechanical alignment angle obtained from applying a standardized varus and valgus stress at 0, 30, 45, 60 and 90 degrees. Each measurement was performed three separate times.

Two tailed student t-tests were performed to analyze whether there was difference in the mean mechanical alignment angle at 0°, 30°, 45°, 60°, and 90° between the well balanced scenario and following a 4 mm recut in the distal femur creating a loose extension gap.


Claus Egidy Stephanie Noelle Michael B. Cross Wolfgang Klauser

Introduction

Total ankle arthroplasty is increasingly used as an alternative to arthrodesis to treat advanced ankle arthritis. In an attempt to assess the survivorship and patient outcome as well as peri- and postoperative complications and possible risk factors, we retrospectively analyzed the demographics, clinical outcome and radiographic characteristics of 100 ankle prostheses (97 patients).

Patients and methods

Between 3/2005 and 5/2010 114 S.T.A.R. Prostheses were implanted by one surgeon at our institution. Indication for TAA was primary and secondary osteoarthritis, 81 cases were posttraumatic. From the 53 female and 44 male patients the mean age was 63 and the mean BMI was 28,4.

11 patients had been smoking for longer than 12 years, 29 patients either had a history of diabetes, peripheral vascular or cardiovascular disease or varicosis.

All operations were performed with a tourniquet, using a standard anterior midline incision. All patients received the same postoperative rehabilitation and follow up program. Postoperative evaluation included the AOFA Score and clinical radiographic follow ups 6 weeks after surgery and yearly thereafter. Additional procedures during surgery included lengthening of the Achilles tendon for 12 patients and fusion of the subtalar ankle for 5 patients.


Bryan J. McEntire Alan Lakshminarayanan B. Sonny Bal Thomas Webster

Oxide ceramics, such as alumina and zirconia have been used extensively in arthroplasty bearings to address bearing wear and mitigate its delayed, undesirable consequences. In contrast to oxide ceramics that are well-known to orthopaedic surgeons, silicon nitride (Si3N4) is a non-oxide ceramic that has been investigated extensively in very demanding industrial applications, such as precision bearings, cutting tools, turbo-machinery, and electronics. For the past four years, Si3N4 has also been used as a biomaterial in the human body; specifically in spinal fusion surgery. As a implantable biomaterial, Si3N4 has unique properties, such as high strength and fracture toughness, inherent chemical and phase stability, low wear, proven biocompatibility, excellent radiographic imaging, antibacterial advantages, and superior osteointegration. This property combination has proven beneficial and desirable in orthopaedic implants made for spinal fusion, spinal disc reconstruction, hip and knee arthroplasty, and other total joints (Fig. 1). The physical properties, shapes, sizes and surface features of Si3N4 can be engineered for each application – ranging from dense, finely polished articulation components, to highly porous scaffolds that promote osteointegration. Both porous and polished surfaces can be incorporated in the same implant, opening a number of opportunities for arthroplasty implant design. Crack propagation modes for in situ toughened Si3N4 differ favorably from those of conventional ceramics, rendering Si3N4 extremely resistant to catastrophic failure in vivo (Fig. 2). Most significantly, our recent work has shown that Si3N4 is resistant to bacterial biofilm formation, colonization and growth, when compared to medical-grade PEEK and titanium. These anti-infective characteristics are particularly valuable for in vivo implantation. We will present the unique properties and characteristics of Si3N4, and compare these to other ceramic and non-ceramic biomaterials. Si3N4 was once used only in industrial applications, but early data show that this novel biomaterial is positively impacting orthopaedic care and will continue to do so into the future.


Brian Park Jorg Leffler Alois Franz Nicholas Dunbar Scott Banks

There is great contemporary interest to provide treatments for knees with medial or medial plus patellofemoral arthritis that allow retention of the cruciate ligaments and the natural lateral compartment. Options for bicompartmental arthroplasty include custom implants, discrete compartmental implants and monoblock off-the-shelf implants. Each approach has potential benefits. The monoblock approach has the potential to provide a cost-efficient off-the-shelf solution with relatively simple surgical instrumentation and procedure. The purpose of this study was to determine if monoblock bicompartmental knee arthroplasty shows evidence of retained cruciate ligament function and clinical performance more similar to unicompartmental arthroplasty than total knee arthroplasty.

Nine females and one male patient were enrolled in this IRB approved study. Each subject received unilateral bicompartmental knee arthroplasty an average of 2.6 years (2.0 to 3.6 years) prior to this study. Subjects averaged 65 years (58–72 years) and 28 BMI (25–31) at the time of surgery. Mean outcome scores at the time of study were 97/95 for the Knee Society knee/function score, 16.4 Oxford score, 6.5 UCLA Activity score and 137 degrees range of motion. Subjects were observed using dynamic fluoroscopy during lunge, kneeling and step-up/down activities. Subjects also received CT scans of the knee in order to create bone/implant composite shape models. Model-image registration techniques were used to determine 3D knee kinematics (Figure 1). Knee angles were quantified using a flexion-abduction-rotation Cardan sequence and condylar translations were determined from the lowest point on the condyle with respect to the transverse plane of the tibial segment.

Maximum knee flexion during lunge and kneeling activities averaged 112°±8° and 125°±7°, respectively. Tibial internal rotation averaged 10°±6° and 12°±10° for the lunge and kneeling activities. For both deeply flexed postures, the medial condyle was 1 mm anterior to the AP center of the tibia while the lateral condyle was 11 mm and 13 mm posterior to the tibial center. For the step-up/down activity, tibial internal rotation increased an average of 2° from 5° to 75° flexion, but was quite variable (Figure 2). Medial condylar translations averaged 4 mm posterior from 5° to 25° flexion, followed by 6 mm anterior translation from 25° to 80° flexion (Figure 3). All knees showed posterior condylar translation from extension to early flexion.

An important potential benefit to any bicompartmental arthroplasty treatments is retention of the cruciate ligaments and maintenance of more natural knee function. The knees in this study showed excellent or good clinical outcomes and functional scores, and relatively activity high levels. There was no evidence of so-called paradoxical anterior femoral translation during early flexion, indicating retained integrity of the natural AP stabilizing structures. Weight-bearing deep flexion during lunge and kneeling activities was comparable to previously reported unicompartmental and well-performing total knee arthroplasty subjects. Kinematics were quite variable between subjects.

Monoblock bicompartmental arthroplasty appears to permit functional retention of the cruciate ligaments, consistent with functionally stable knees. Further efforts should focus on the specific surgical placement of off-the-shelf bicompartmental implants to optimize knee function and provide consistent knee mechanics.


O. Andres Barrera Curtis Hartman Kevin Garvin Timothy Growney Hani Haider

Introduction

Computer aided surgery aims to improve surgical outcomes with image-based guidance. Navigated Freehand bone Cutting (NFC) takes this further by eliminating the need for cumbersome mechanical jigs. Multiple previous experiments on plastic and porcine bones, performed by surgeons with different level of expertise, suggested that the NFC technique was feasible. This study pushes NFC further by using the technique to perform complete total knee replacement (TKR) surgeries on cadavers (including implant cementing of tibia and femur).

Materials and Methods

A single surgeon performed a series of TKR surgeries on full cadaveric legs. Cruciate sacrificing implants were selected because these were considered more challenging for a freehand cutting approach due to the extra number and complexity of the cuts needed around a posterior stabilizing post recess when present.

A proprietary NFC prototype system was used, with real time graphics to indicate where/how to cut the bone without jigs. The system comprised a navigated smart oscillating saw, reciprocating saw and drill without any of the conventional jigs typically used in TKR.

The tasks performed included (and were grouped) to include pre-surgical planning, incision, placement of navigation pins & markers on tibia and femur, bone registration, marking and cutting, cut surface digitization (for quality assessment), implant placement and cementing, assessment of implant fit and location, and pin removal and wound closing.


Adrian Barrett Barry Andrews Justin Cobb

Introduction

The introduction of the Stanmore Implants Savile Row mobile-bearing UKA procedure in July 2011 marked a world first – the use of a patient-specific knee implanted with robotic technology – the Sculptor Robotic Guidance Arm (RGA). This union gives a truly personalised solution by designing an implant for each patient based upon preoperative CT data and using Sculptor RGA to prepare the bone accurately so that the implant is correctly positioned as planned. The purpose of this study is to evaluate the accuracy of Sculptor RGA both in-vitro and in-vivo. We report on the accuracy of our first clinical procedures.

Methods

In-vitro:

CTs of plastic-bones were used to create plans for Sculptor RGA, establishing a relationship between the implant position and plastic-bone (planned-transform). Sculptor RGA was then used to prepare bones for 16 UKA implants mimicking the clinical set-up. The implants were placed in the prepared bones without cement. A coordinate-measuring-arm was used to register a)the bone, and b)the implant in relation to the bone (achieved-transform). The difference between planned-and-achieved transforms gives the error in implant position.

In-vivo:

Preoperative CTs of 8 OA patients, acquired using the low-dose Imperial Knee CT protocol, were used to plan the position and the shape of the patient-specific implants. Intra-operatively, Sculptor RGA was used to register and prepare the bone and the implants were cemented in place. Post-operative CTs were also acquired. Two techniques were used to measure planned-to-achieved positions of the implants: 1). Preoperative-to-postoperative CT image registration followed by extraction of the achieved implant position and comparison with the plan, 2). Surface-to-surface registration of bone-models segmented from the preoperative and postoperative CTs followed by extraction of the achieved implant position and comparison with the plan.


Richard Beaver Karen Sloan Inder Gill

As part of a prospective RSA study into a new design of short-stem, trabecular metal, Co-Cr femoral components with modular necks and metal on polyethylene articulation, three patients presented with almost identical symptoms of pain and a large avascular mass within the operated hip. All three cases came to exploration and similar findings of a solid pseudotumour within the hip joint were found in all thee cases. Infection was not present. All cases were submitted to histology and reviewed by a pathologist with specific interest in tissue reactions to foreign materials. All three cases showed histological features classical of published descriptions of ALVAL (Aseptic Lymphocyte-dominated Vasculitis Associated Lesion). A consistent finding was fretting corrosion of the neck-stem junction. These cases demonstrate that Co and Cr ions can provoke adverse tissue reactions even in the absence of metal/metal articulations. This has design implications for all modular Co-Cr necks. The stem used in this study has been voluntarily withdrawn from the Australian market but is still being implanted in Europe. We make recommendations that modular trunnion-style Co-Cr necks not be used and alternative materials and design solutions be sought.


Harry Benjamin-Laing Jenni Tahmassebi Fares Haddad

Introduction

The purpose of this study was to evaluate the functional outcome in the medium and long-term of hip resurfacing in comparison with cementless hip replacement in patients under the age of 55.

Methods

Eighty patients were enrolled between 1999 and 2002. Twenty-four were randomised (11 hip re-surfacing, 13 total hip replacement), 18 refused hip resurfacing and chose cementless total hip replacement with a 32 mm bearing, 38 insisted on re-surfacing. All the patients have been reviewed at a minimum follow-up of 8 years and a mean of 10.1 years. Patients were assessed clinically and radiographically at one year, five years, eight years and ten years. Outcome measures included EQ 5, SF 36, Oxford, Harris hip, UCLA and UCH scores.


Harry Benjamin-Laing Sujith Konan Faisal Rayan Andrew Manktelow F S Haddad

Infected periprosthetic fractures around total hip arthroplasties are increasingly common and extremely challenging problem. The purpose of the study was to review the experience of two tertiary referral units managing infected periprosthetic femoral fractures using interlocking long-stem femoral prostheses either as temporary functional spacers or as definitive implants.

Methods

A prospective review of 19 patients managed at two tertiary referral units between 2000 and 2011. Each patient was diagnosed and managed according to similar institutional protocols. Investigation through aspiration and biopsy of periprosthetic tissue supplemented haematological tests to confirm infection. The Cannulock uncoated stem was used in 14 cases, and the Kent hip prosthesis in 5 cases. Allograft struts were used in patients with deficient bone stock.

Results

The mean follow-up for the series was a 53 months (range, 24–99 months). 13 patients underwent definitive revision within 7.9 months (range, 6–10 months; SD, 2.2 months). In 6 cases we implanted an extensively porous-coated stem, in 4 cases a tapered distally fixed cementless stem was used, and in 3 cases a proximal femoral replacement was used. There were no reinfections after the second stage revisions in these patients. 2 patients were offered further staged surgery due to persistently raised inflammatory markers but being mobile and relatively painfree declined. They are being managed in the community on oral antibiotics. Satisfactory outcome was noted in all cases, and in 13 cases, revision to a definitive stem was undertaken after successful control of infection and fracture union. The average postoperative Harris Hip score was 83 (range 79–89). All patients returned to their low to moderate premorbid functional state after discharge.


Georg Bergmann Ines Kutzner

Introduction

Realistic knee contact forces and moments are needed for testing implant wear, fatigue and static strength, for analysing strains and remodelling at interfaces, as ‘gold standard’ for analytical musculo-skeletal models, or as input for finite element models. ISO 14243 defines the loading conditions for wear tests, but the defined loads from walking are based on very old data.

Methods

Therefore we compared the ISO loads with data obtained from instrumented tibial components with telemetric data transmission. Cruciate ligaments sacrificing total knee implants (Innex FIXUC, Zimmer) were equipped with inductively powered electronics and strain gauges to measure 6 force and moment components acting on the tibial component [1]. The coordinate system is fixed at the tibial component. -Fz acts inferiorly, +Fy anteriorly, and +Mz if the tibia is rotated outwards with the femur being fixed.

Loads were measured in 8 subjects (70 years Ø) during 10–20 repeated cycles of free walking at about 4 km/h. For each subject the load components were normalized to 75 kg body weight (BW) and averaged [2] (‘Aver75_1Subj’). These individual results were averaged again and delivered the ‘standard’ load components ‘Aver75’. From all 8 ‘Aver75_1Subj’ patterns of the resultant force Fres the highest peak value was taken and divided by the peak value of Fres in ‘Aver75’. The obtained factor was then multiplied with all ‘Aver75’ components and the BW increased to 100 kg. The final ‘standard’ components (‘High 100’) describe the highest average loads to be expected in a heavy-weight subject. This worst case but still realistic conditions should be used for wear and fatigue tests.


Nicky Bertollo Rami Sorial Adrian Low William Walsh

Introduction

The marriage of rapid prototyping technologies with Arthroplasty has resulted in the fabrication and use of cutting jigs and guides which are tailored to a patients' individual anatomy. These disposable cutting blocks are designed based on input parameters obtained from pre-operative CT and MRI scans and manufactured using 3-D printers. Indirect benefits include a reduction in inventory and a decrease in the burden for central sterilising units. This approach is advantageous for the surgeon in the attainment of ideal mechanical alignment, which is known to be associated with an improved clinical outcome and implant longevity. This study evaluated the postoperative alignment parameters from a single surgeon series of patients following TKA with the Signature (Biomet) system.

Methods and Materials

The postoperative alignment of a single surgeon series of 60 consecutive patients receiving a Vanguard cruciate retaining TKR (Biomet) using the Signature patient-specific surgical positioning guides was performed. Postoperative CT and preoperative templating MRI scans were imported into Mimics 14.0 (Materialise, Belgium) where specific bony landmarks were identified in both data sets. A subset of these points was used to transform the MRI data into the CT coordinate frame to enable the computation of femoral mechanical alignment in the absence of a full-length lower limb CT scan. CT and transformed MRI landmarks were then imported into ProEngineer (PTC, MA) where angular measurements were made by projecting axes onto anotomical planes. Flexion, rotation, valgus/varus of the femoral component and posterior slope, rotation and valgus/varus of the tibial component were computed. Femoral rotation was referenced to the trans-epicondylar axis as opposed to Whiteside's line. Overall limb alignment was determined based on individual component position.


John Blaha Tomoharu Mochizuki Osau Tanifuju Shin Kai Takashi Sato Hiroshi Yamagiwa Go Omori Yoshio Koga Noato Endo

To explain the knee kinematics, the vector of the quadriceps muscle, the primary extensor, is important and the relationship of the quadriceps vector (QV) to other kinematic and anatomic axes will help in understanding the knee.

Knee kinematics is important for understanding knee diseases and is critical for positioning total knee arthroplasty components. The relationship of the quadriceps to knee has not been fully elucidated. Three-dimensional imaging now makes it possible to construct a computer based solid model of the quadriceps and to calculate the vector of the muscle as individual parts and as a whole. Two studies are presented, one American and one Japanese subjects.

Using CT data from subjects who had CT for reasons other than lower extremity pathology (American) or specifically for the study (Japanese), 3-D models of each quadriceps component (vastus medialis, intermedius, lateralis and rectus femoris) were generated. Using principal component analysis for direction and volume for length, a vector for each muscle was constructed and addition of the vectors gave the QV. Three anatomic axes were defined: Anatomic Axis (AA) – long axis of the shaft of the femur; Mechanical Axis (MA) center of the femoral head to the center of the trochlear and the Spherical Axis (SA) – a line from the geometric center of the head of the femur to the geometric center of the medial condyle of the femur at the knee.

Fourteen American cases (mean age 39.1, 9 male 5 female) and 40 Japanese subjects (mean age 29.1, 21 male, 19 female) were evaluated. In all subjects the quadriceps vector at the level of the center of the femoral head was anterolateral to the center of the femoral head. The position of the QV was more lateral in Japanese compared to Americans; and, in Japanese, the vector was more lateral and posterior for women than for men. In both study populations, the QV was most closely aligned with the SA as compared to the AA or the MA.

The vector representing the quadriceps pull, originating at the top of the patella, progresses proximally toward the neck (not the head) of the femur. With the femur in anatomic position in the coronal plane, the vector crosses the femoral neck lateral to the femoral head approximately at the midpoint of the neck. While there were significant differences between the passing point of the vector based on sex and ethnicity, the QV vector most closely parallels the SA (< 1° different) for all subjects in this study. The relationship of the SA to the kinematic flexion axis (KFS) of the knee is being evaluated with the hypothesis that the relationship is 90°. If this is correct, the SA may prove a robust axis to which to align total knee arthroplasty.

We conclude that the QV as calculated progresses from the top of the patella to the mid-femoral neck and the SA is most closely parallel to this vector.


Ben Bolland Christian Maul Richard Cook Anne Roques Mike Tuke Robert Wood Jeremy Latham

The poor outcome of large head metal on metal total hip replacements (LHMOMTHR) in the absence of abnormal wear at the articulating surfaces has focussed attention on the trunnion / taper interface. The RedLux ultra-precision 3D form profiler provides a novel indirect optical method to detect small changes in the form and surface finish of the head taper as well as a quantitative assessment of wear volume. This study aimed to assess and compare qualitatively the tapers from well functioning small diameter, with poorly functioning LHMOMTHR's using the above technique.

Method

3 groups of retrieval tapers were analysed (Group 1: 28 mm CoCr heads from well functioning MOMTHRs (n=5); Group 2: Large diameter CoCr heads from LHMOMTHRs revised for failure secondary to adverse reaction to metal debris (n=5); Gp 3 (control): 28 mm heads from well functioning metal on Polyethylene (MOP) THRs; n=3). Clinical data on the retrievals was collated. The Redlux profiling of modular head tapers involves a non direct method whereby an imprint of the inside surface of a modular head is taken, and this is subsequently scanned by an optical non contact sensor using dedicated equipment [1]. The wear was also measured on the bearing surface [1]. RedLux profiling of the tapers produced a taper angle and 3D surface maps. The taper angles obtained with the Redlux method were compared to those obtained using CMM measurement on 3 parts. The Redlux profiling, including imprints, was also repeated 3 times to gauge potential errors.

Results

There was no difference in mean 12/14 taper angles between groups. There was no difference in volumetric and linear wear at the bearing surface between groups. Only the LHMOMs showed transfer of pattern from the stem to the internal head taper, with clear demarcation of the contact and damaged area between head taper and stem trunnion (see figure 1 – interpretation of head taper surface features demonstrated using Redlux optical imaging). 3D surface mapping demonstrated wear patterns compatible with motion or deformations between taper and trunnion in the LHMOM group. These appearances were not seen in tapers from small diameter MOM and MOP THRs (see Figure 2).


Ben Bolland Simon Tilley Charles Tilley Richard Cook Jeremy Latham

Pseudotumour formation is being reported with increasing frequency in failing metal-on-metal hip resurfacings and replacements. This mode of failure complication has also been reported with metal-on-polyethylene bearing bearings when it is usually associated with evidence of surface corrosion and no apparent wear at the head–neck taper.

We present a case with evidence of taper wear and damage secondary to corrosion in an uncemented total hip replacement with a metal on polyethylene articulation (TMZF (Titanium, Molybdenum, Zirconium and Ferrous) Accolade® stem, Trident® HA coated acetabular shell, Low Friction Ion Treatment (LFIT™) Cobalt-Chrome anatomic head (40 mm), X3® polyethylene liner)

Case

A 69 year old woman had a THR in 2008. A year later she started to complain of lateral based hip pain. Clinical examination and initial imaging indicated trochanteric bursitis and heterotopic bone formation. The symptoms became worse over the next 3 years and the patient was listed for exploration and excision of heterotopic bone.

Surgical findings

Extensive pseudotumour was encountered deep to bursa and adherent to capsule. Abductors, external rotators and vastus lateralis were spared. There was minimal calcar osteolysis and marginal erosion in superior acetabulum. There was no obvious wear on the articulating surfaces of the femoral head and polyethylene inlay of the socket nor was there any evidence of neck-to-rim impingement or edge loading. There was visible blackening of both the taper and trunnion after femoral head removal.


Michael Zywiel Khalid Syed Christopher B. Overgaard Angela C. Cheung Thomas Turgeon Jan-M Brandt

Revision of fractured ceramic-on-ceramic total hip replacements with a cobalt-chromium (CoCr) alloy-on-polyethylene articulation can facilitate metallosis and require further expensive revision surgery [1–3]. In the present study, a fifty-two year old male patient suffered from fatal cardiomyopathy after undergoing revision total hip arthroplasty. The patient had received a polyethylene-ceramic acetabular liner and a ceramic femoral head as his primary total hip replacement. The polyethylene-ceramic sandwich acetabular liner fractured in vivo after 58 months and the patient underwent his first revision surgery where he received a Vitamin E stabilized acetabular Polyethylene (PE) liner and a CoCr alloy femoral head with documented synovectomy at that time. After 15 months, the patient was admitted to hospital in cardiogenic shock, with retrieval of the bearing components. Before the second revision surgery, peak serum cobalt levels measured 6,521 μg/L, 78-times greater than serum cobalt levels of 83μg/L associated with cobalt poisoning [4]. Serum titanium levels found in the patient measured 17.5 μg/L) normal, healthy range 0–1.4 μg/L). The retrieved CoCr alloy femoral head had lost a total of 28.3g (24% or an estimated amount of 102 × 10−9 wear particles (∼2 μm diameter) [1]) within 16 months of in vivo service. Despite initiating a cobalt chelating therapy, the patients' cardiac left ventricular ejection fraction remained reduced at 6%. This was followed by multi-organ failure, and ultimately the patient passed away shortly after being taken off life support. Embedded ceramic particles were found on the backside and articular surfaces of the Vitamin E-stabilized PE acetabular liner. Evidence of fretting wear on the titanium (Ti) alloy acetabular shell was present, possibly explaining the increased serum Ti levels. Scanning electron microscopy and energy dispersive X-ray analyses confirmed Ti alloy transfer on the embedded ceramic particles on the backside PE liner surface and CoCr alloy transfer on the embedded ceramic particles on the articular PE liner surface. A fractured ceramic-on-ceramic total hip replacement should not be revised to a CoCr alloy-on-polyethylene articulation irrespective of concurrent synovectomy [5] as it can cause severe, third-body wear to the CoCr alloy femoral head that can lead to metallosis with fatal, systemic consequences.


Jan-M Brandt Trevor Gascoyne Alex Vecherya Thomas Turgeon Eric Bohm

Ceramic-on-ceramic (C-C) total hip replacements (THRs) are an attractive option for young, active patients [1, 2]. However, more clinical data is necessary to establish the reasons of failure of contemporary C-C THRs in vivo. The objective of the present study was to assess the surface damage on retrieved C-C THRs and determine possible influential factors that may explain their in vivo performance. Thirty-five C-C retrievals of material type Biolox® forte (n=28) and Biolox® delta (n=7) (CeramTec AG, Plochingen, Germany) were collected after a mean of 3.7 ± 3.2 years in vivo. Semi-quantitative surface damage assessment [3] was performed on all retrievals to obtain both a damage score (DS) (Fig. 1). Contact profilometry was performed on the retrieved femoral heads to characterize the type of surface damage (metal transfer, stripe wear). Scanning electron microscope (SEM) images were obtained from two femoral heads displaying areas of typical surface damage. The implantation period correlated with the damage score (DS) of the femoral heads (R=0.573, p<0.001) and the acetabular cups (R=0.592, p<0.001). However, the metal transfer DS of the femoral heads did not correlate with implantation period (R=0.185, p=0.29). Surface roughness of metal-transfer areas were positively skewed (additive metal transfer) while the stripe damage areas were negatively skewed (grain removal), as evidenced by SEM analysis. Stripe damage was observed on both the Biolox® forte and Biolox® delta retrieved femoral heads; however, the extent of grain removal appeared less severe on the Biolox® delta retrieved femoral heads due to their overall smaller grain size (Fig. 2). Inclination angles > 45° was associated with a greater DS rate [DS/time of implantation], which had also been suggested elsewhere [4]. Four patients reported squeaking in their C-C THRs; one of which was a 54 yr-old male patient who completed three full marathons with his implant. In this his case, the DS for this retrieval was below average, with metal-transfer being the only macroscopic damage feature. Fracture of the acetabular liner occurred in three patients, all of which had malpositioned components. Metal-transfer on the ceramic surface could possibly cause a local break down of the fluid film and may facilitate, in addition to an increased inclination angle, stripe damage via an adhesive wear mechanism. Therefore, direct contact between the Ti-alloy acetabular shell and the ceramic femoral head should be avoided at primary surgery. C-C THRs remain an attractive option for young, active patients, but care must be taken during implantation to appropriately position the acetabular cup and to avoid unwanted metal-transfer as such alteration at the bearing interface may change implant tribology.


George Branovacki Thomas Prokop Alyssa Huizinga Luis Redondo

Introduction

Proper femoral stem and acetabular implant orientation is critical to the initial and long-term success of THA. Post-operative determination of cup and stem anteversion is important in cases of hip instability and planning isolated component revisions. At ISTA 2010 Dubai, we introduced a novel, simple stem modification that can be added to any stem design to help assess stem, and possibly cup anteversion with plain post-operative radiographs throughout the lifespan of the implant. [Figure 1] As the stem is rotated, the visible hole pattern changes. [Figure 2] This study was performed to further validate the accuracy and potential usefulness of this design.

Methods

We prospectively reviewed 100 consecutive THA cases using the stem reference hole modification on rectangular tapered Zweymuller-type stems implanted from September 2010 to May 2012. Post-operative hip/femur CT scans were obtained to determine the true cup and stem orientation to validate and quanitify the precision of the reference holes. Intra-operative estimates of stem anteversion and combined anteversion (Ranawat Sign) were recorded. Post-operative radiograph measurement of stem anteversion (AP hip x-ray with leg in neutral rotation) was obtained and compared to the CT scan measurement referencing stem rotation relative to the knee epicondylar axis. [Figure 3] In addition, we compared the modified reference hole anteversion assessment to a control group of original unmodified stems assessed using the same methods.


George Branovacki Aliasgar Dalal Thomas Prokop Luis Redondo Sam Chmell

Introduction

Proper total knee arthroplasty balancing relies on accurate component positioning and alignment as well as soft tissue tensioning. Technology for cutting guide alignment has evolved from the “free hand” technique in the 1970's, to traditional intra/extra medullary rods in the 1980's and 1990's, to computer navigated surgery in the 2000's, and finally to patient specific custom cutting blocks in the 2010's. The latest technique is a modification to conventional computer navigation assisted surgery using Brainlab's Dash™ TKA/THA software platform that runs as an application on an Apple IPod held by the surgeon in a sterile pouch in the operative field. The handheld IPod touch screen allows the surgeon to control all aspects of the navigation interface without needing the assistance of an observer to manually run the software. In addition, the surgeon is able to always focus on the operative field while ‘navigating’ without looking up at a remote image monitor. This study represents a prospective analysis of the first 30 U.S. TKA cases performed using the newly commercially released Dash™ software using an IPod during surgery.

Methods

Thirty consecutive primary total knee arthroplasty procedures were performed using the Dash™ software (Brainlab) and an IPod touch (Apple). A cemented Genesis II (Smith Nephew) posterior stabilized implant was used in all cases. Femoral and tibial sensor arrays were placed in meta-diaphyseal regions for bone registration. We recorded the time spent to set up the arrays, time for bony registration, time to navigate the cutting guides, and the tourniquet time. After all bone cuts were completed, the tibial cut was manually measured with an intramedullary angle check instrument to assess the planned zero degree posterior slope and neutral varus/valgus coronal alignment. Final femoral and tibial component alignment and orientation was measured on standing long axis AP and lateral radiographs. Measurements from the Dash™ alignment group were compared to 30 consecutive surgeries using the author's traditional technique of intramedullary cutting block alignment (control group).


JM Brinkman PS Bubra Peter Walker William Walsh Warwick Bruce

In order to emulate normal knee kinematics more closely and thereby potentially improve wear characteristics and implant longevity the Medial Pivot type knee replacement geometry was designed. In the current study the clinical and radiographic results of 50 consecutive knee replacements using a Medial Pivot type knee replacement are reported; results are compared to the Australian Orthopaedic Associations National Joint Replacement Registry. The patients' data were crossed checked against the registry to see if they had been revised elsewhere. After a mean follow-up of 9.96 years results show that the Medial Pivot Knee replacement provides good pain relief and functional improvement according to KSS and Womac scores and on subjective patient questionnaires. There was one minor revision; insertion of a patella button at 6.64 years FU. There were no major revisions; all implants appeared to be well fixed on standard radiographic examination. While the revision rate for the Medial Pivot knee according to the Australia Joint Registry results is higher compared to all other types of knee replacements in the registry, and to what is reported in the literature on the medial pivot knee, it is not in the current series. Revision rate was similar to what is reported on in the literature, but after a longer follow-up period. However, long term follow-up is required to draw definitive conclusions on the longevity of this type of implant.


Danilo Bruni Francesco Iacono Mirco Lo Presti Bharat Sharma Giovanni Raspugli Maurilio Marcacci

INTRODUCTION

Conventional surgical exposures are usually inadequate for 2-stage revision knee replacement ofinfected implants. Reduced range of motion, extensor mechanism stiffness, peripatellar contracture and soft tissue scarring make patellar eversion difficult and forced eversion places the integrity of the extensor mechanism at risk. On the contrary, a wide exposure is fundamental to allow complete cement spacer removal, soft tissue balancing, management of bone loss and reimplantation without damaging periarticular soft tissues.

OBJECTIVES

To compare the long-term clinical, functional and radiographic results and the reinfection rate of the quadriceps snip approach and the tibial tubercle osteotomy in 2-stage revision knee replacement performed for septic loosening of the primary implant.


Danilo Bruni Francesco Iacono Mirco Lo Presti Giovanni Raspugli Bharat Sharma Maurilio Marcacci

INTRODUCTION

The purpose of our work was to evaluate changes in clinical scores, passive knee kinematics and stability after mobile bearing TKA surgery.

MATERIAL AND METHODS

60 patients were treated with a mobile bearing prosthesis (Gemini, Waldemar Link, Hamburg, Germany). PCL was always resected. Inclusion criteria were BMI >30, age range 60–80 yrs. Preoperative KSS, KOOS and SF36 scores were recorded. Surgeries were performed with a navigation system (BLU-IGS, Orthokey Italia, Firenze, Italy) to verify bone cuts, ligament balancing and implant positioning. Kinematic tests were executed to determine: tibial rotation and femoral translation through flexion range. Stability tests were performed using varus-valgus stress in extension and at 30° of flexion and drawer test. Acquisition were perfomed with menisci and cruciate ligaments intact, and repeated after final implant fixation. Clinical scores were recorded at 6 months follow-up.


Stephen Burnett Rajesh Nair Duncan Jacks Christine Hall

Introduction

Unicompartmental knee arthroplasty (UKA) is a successful procedure for medial compartment osteoarthritis (OA). Recent studies using the same implant report a revision rate of 2.9%. Other centers have reported revision rates as high as 10.3%. The purpose of this study was to retrospectively review the clinical results of Oxford Phase 3 UKA's performed in the setting of isolated medial compartment OA and to compare our results to the previous mid-term studies. Our secondary goal was to determine reasons for revision and evaluate selected independent predictors of failure.

Methods

A retrospective review of 465 Oxford Phase 3 medial UKA's performed on 386 patients (222 female; 164 male) with isolated medial compartment OA. The average age at surgery was 69.5 years (40–88). Outcome measures included: Knee Society Scores(KSS), Oxford Knee Scores(OKS), SF-12, WOMAC, revision rates, and patient satisfaction. We evaluated independently predictors of failure including: gender, body mass index(BMI), number of previous surgeries, implant sizes, cement technique (simultaneous vs staged), cement type. Revision rates based upon the polyethylene thickness (defined as thin 3–4 mm; medium 5–6 mm; thick 7–9 mm). The need for stems and augments and the degree of constraint required at revision to a total knee arthroplasty (TKA) were evaluated.


Lucas Burton Joel Weisenburger Kevin Garvin Hani Haider

Background

The constraint of total knee replacement (TKR) implants is not simply defined and many of the factors that influence it are not well understood. Variability in the constraint of different TKR implants designed for the same indication (e.g. cruciate-retaining, or posterior-stabilized) have been previously demonstrated, but these differences among implants have yet to be simply quantified. Furthermore, the relative importance of several variables on the implant constraint remains unknown. The purpose of this study was to quantify the differences in constraint that exist between different implant designs, and to examine the effects of axial load and flexion angle on the constraint of current cruciate-retaining (CR) TKR components.

Methods

Four contemporary CR TKR designs underwent laxity testing using a multi-axis mechanical test machine. Implants were tested at flexion angles of 0°, 20°, 90° and maximum flexion and axial loads of 712 N (1 BW) and 1424 N (2 BW). Friction-free motion in all secondary degrees of freedom was allowed. Force-displacement curves were generated for each testing condition in both anterior-posterior (AP) and rotational tests. AP constraint (N/mm) and rotational constraint (Nm/deg) were then calculated.


Jae-Wook Byun Kyung-Soon Park WooBin Jung Yoon Taek Rim

Purpose

Bilateral simultaneous and staged total hip arthroplasty has been issues in terms of safety and costs with development of surgical technique, postoperative medical care. The purpose of this prospective study is to compare the outcomes of simultaneous and staged bilateral operations, in terms of outcome, safety, and socioeconomic-effectiveness.

Patients and Methods

All patients(470 cases) that underwent simultaneous or staged bilateral THA using modified minimally invasive two-incision technique between January 2004 and November 2009 were registered, and after exclusion divided into two groups; simultaneous bilateral THA group (Group A: 171 patients) and staged bilateral THA group (Group B: 64 patients) by patient's condition and preference. Staged operations were performed at the time when patients want to get surgery due to undurable pain. For clinical evaluations, amounts of blood loss, blood transfusion, postoperative morbidity and mortality were compared. And for socioeconomic-effectiveness, costs for hospitalization and time for returning to previous job were investigated.


James Yoon Michel Le Duff Alicia Johnson Karren Takamura Edward Ebramzadeh Pat Campbell Harlan Cabot Amstutz

It has been suggested that metal ion levels are indicative of in vivo bearing performance of metal-on-metal hip replacements. A cobalt or Chromium level of 7μg/L or higher is proposed to be indicative of a bearing malfunction and the need for clinical intervention. Component design, size, acetabular orientation, patient gender and activity level have been suggested as factors leading to accelerated wear and elevated metal ions. The contact patch to rim (CPR) distance is a calculation that describes the distance from the point where a theoretical joint reaction force intersects the cup to the acetabular rim for a patient in standing position, dependent on the coverage, size, and orientation of the acetabular component. It has been suggested that CPR distance determines the hip joint susceptibility to edge loading, and the risk for increased wear and high ion levels (Langton et al JBJS Br 91: 2009). This study examined the effects of patient activity, gender, and CPR distance on serum metal ion concentrations in a series of patients treated with one type of metal on metal hip resurfacing arthroplasty (MMHRA) performed by one surgeon.

182 patients (73 females and 109 males)with a unilateral Conserve Plus (WMT, TN USA) MMHRA and had who had provided blood for metal ion analysis data from December 2000 to June 2011 were retrospectively studied. Only measurements made more than 12 months after surgery were included in order to exclude hips that had yet to reach steady-state wear. For patients with multiple draws, the most recent qualifying draw was used. Activity level was assessed by the UCLA activity score. The mean age was 51.5 years (20.0 to 77.5 years). The mean follow-up time for the last blood draw was 70 months (range, 12 to 165). Serum cobalt (CoS) and chromium (CrS) levels were analyzed using inductively coupled plasma mass spectrometry in a specialized trace element lab. Using acetabular abduction and anteversion measured by EBRA, component size, and reported coverage angle of the acetabular component, the CPR distance was calculated as previously described. Multiple logistic regression was performed to identify significant relationships between high metal ion levels (7 μg/L or greater) and gender, activity and CPR distance.

The median CoS level for the entire cohort was 1.13 μg/L (range, 0.15 to 175.30), and the median CrS level was 1.49 μg/L (range, 0.06 to 88.70). The average CPR distance was 13.8 mm (range, 3.2 to 22.1). There was a significant association between low CPR values and CoS and CrS. There was a 37-fold increase in the risk of CoS >7μg/L (p=0.005) and 11-fold increase in the risk of CrS > 7μg/L (p=0.003) when CPR distance was 10 mm or less. No associations were shown for gender and UCLA activity scores.

CPR distance was found to be a reliable predictor of ion levels > 7μg/L and appears to be a useful indicator to evaluate the multi-factorial process of edge-loading and wear. Patients with a low CPR distance should be monitored for increased metal ion levels.


Harlan Cabot Amstutz Pat Campbell Frederick J. Dorey A Johnson A Skipor Joshua J Jacobs

The Conserve® Plus (Wright Medical Technology Inc., Arlington, TN) was introduced clinically in the United States in 1996. A study of the serum cobalt and chromium ion levels was started in 2000 in our center to monitor the metal ion levels over time as part of an FDA clinical trial.

Thirteen male and five female patients received this resurfacing for idiopathic osteoarthritis (14), post-traumatic degenerative changes (3) or developmental dysplasia (1). Fourteen received a unilateral implant but four subsequently received a contralateral device from 52 to 86 months post-op. Four patients had bilateral resurfacings done in a one-stage procedure. All surgeries were performed by the senior author. None of these patients had known exposure to cobalt or chromium, kidney disease or other metal implants elsewhere in their bodies. Each prospectively provided blood samples and then yearly thereafter to measure cobalt and chromium levels for up to 11 years. Metal levels were measured using atomic absorption spectrophotometry and inductively coupled plasma mass spectrometry by a specialized trace element analysis laboratory. Acetabular component position was evaluated using Einzel-Bild-Röentgen-Analysis (EBRA) software. Contact patch to rim (CPR) distance was computed as described by Langton et al JBJS Br 91: 2009. A mixed model linear regression analysis was performed to evaluate long term trends, and multivariate analysis was performed to examine effects of implant and patient covariates on the metal ion levels.

One bilateral patient underwent revision for femoral loosening, all other patients were clinically well-functioning at the time of last follow-up (ave 89 mos). The median pre-operative Co was below the detection limit (d.l) of 0.3μg/L and the median pre-operative Cr was 0.069μg/L (d.l. 03μg/L). Metal levels increased within the first year then decreased and stabilized (fig 1). For unilaterals over all time intervals, the median Co was 1.06 μg/L, while the median Cr was 1.58 μg/L. For bilaterals, the mean post-operative Co was 2.80 μg/L, while the mean Cr was 5.80 μg/L. Generally, Cr levels were higher at all time points than Co. Bilateral patients had Co values 1.96 times greater on average than the unilateral patients (p<0.001). None of the possible covariates studied (femoral size, cup abduction angle, cup anteversion, CPR distance, activity, BMI and testing method) were related to the assay values.

The results of this study have shown that serum metal levels in well functioning implants can be low and do not increase over time. These are among the lowest levels reported for resurfacing devices and comparable to levels reported for well functioning small diameter metal-on-metal total hips. The study is limited due to the relatively small sample size and limited range of values for the covariates studied. However, it included patients who were active, female or bilateral and we collected ion levels up to 11 years. We now recommend that patients who have well-oriented Conserve Plus components with stable radiographic interfaces and no incidences of unexplained pain or hip noises be scheduled for follow-up every 2–3 years, rather than annually.


Jake D Cao Kevin J Laws Nick Birbilis Michael Ferry

Introduction

In recent years, there has been a growing interest in bioresorbable metals. Orthopaedic components made from these materials do not require removal by secondary surgery, and offer superior load bearing capability compared to the existing biodegradable polymers.

Research on bioresorbable metals have largely focused on alloys based on a subset of the Mg-Zn-Ca ternary system [1, 2], which are pre-existing elements inside the human body. Cytocompatibility assessments of these alloys have reported no signs of inflammation or adverse cellular reactions [2-4]. Rather than designing for longevity, bioresorbable metals rely on their tendency to corrode in a controlled manner. Hence, controlling their corrosion rates is of utmost importance. In the present work, we have explored the effect of compositional variation on the properties of the Mg-Zn-Ca amorphous metals. Subsequent characterisations are performed to assess their suitability as a bioresorbable material.

Materials and Methods

A mixture of pure elements and master alloys, namely magnesium, zinc, calcium, and Mg-Ca master alloy, were melted in an induction furnace, followed by injection casting to produce the amorphous metallic samples. Pure magnesium (crystalline) was also used in the subsequent characterisation tests for comparison. The thermophysical properties of the as-cast amorphous metals were characterized using x-ray diffraction (XRD) and differential scanning calorimetry (DSC). The biocorrosion performance was assessed by a combination of immersion, potentiodynamic polarisation (PDP) and hydrogen evolution studies. These tests were conducted in cell media, with a sodium bicarbonate buffer, at 37°C and pH 7.4 in a humidified CO2 atmosphere.


Jerry Chen Chin Pak Lin Andy Yew Darren Tay Shi-Lu Chia Ngai Nung Lo Seng Jin Yeo

Introduction

Total knee arthroplasty (TKA) has proven to be cost-effective and efficative in the treatment of osteoarthritic knees. Although traditional computer navigation systems improve implant placement, they require fixation of the femoral and tibial reference arrays for software recognition using anchoring pins. This increases the risk of bony fracture, pin sites infection and osteomyelitis. Our study aims to investigate the accuracy of a new inless navigation system (Brainlab VectorVision Knee 2.5 Navigation System) that would avoid these complications.

Methods

119 patients were prospectively recruited over a year. These patients all underwent a primary TKA by a senior surgeon who performs more than 200 TKAs per annum. They were divided into two surgical technique arms. In Group 1, 74 patients underwent TKA using conventional techniques. In Group 2, 45 patients underwent TKA using a pinless navigation system.

Post-operative films were taken and three radiographic measurements were measured: 1) Hip-Knee-Ankle Angle (HKA); 2) Coronal Femoral-Component Angle (CFA); 3) Coronal Tibia-Component Angle (CTA) (Figure 1). Two reviewers blinded to the surgical method performed the measurements on the radiographic films on two separate occasions.


Samuel MacDessi Darren Chen

Introduction & Aims

Intravenous administration of tranexamic acid (TXA) has been shown to be effective in reducing blood loss and transfusion requirements in total knee arthroplasty (TKA). However, concern exists that I.V. TXA may heighten the risk of venous thrombo-embolism. The intra-articular administration of TXA is an attractive and simple option to deliver this agent locally with minimal systemic effects on inducing hypercoagubale states. In this study, we analysed the effect of varying dosages of intra-articular tranexamic acid on blood loss in TKA.

Methods

176 patients who underwent a unilateral TKA for osteoarthritis were retrospectively analysed. Patients were excluded if they underwent a revision knee arthroplasty, concurrent removal of hardware, extensive synovectomy, or lateral patellar retinacular release. All patients underwent a primary cemented posterior stabilised TKA by 2 surgeons using a medial parapatellar approach. Tourniquet was only inflated for initial exposure and intra-articular drains were not used. Patients were separated into three groups; a control group (n=56) who did not receive TXA, and 2 treatment groups who received intra-articular TXA with doses of 1500 mg (n=60) or 3000 mg (n=60). Once the wound was closed, tranexamic acid was injected intra-articularly via an epidural pain catheter. Haemoglobin (Hb) levels were taken pre-operatively and on post-operative days 1 and 2. The primary outcome measure was mean difference in Hb drop between the three groups.


Hong-Man Cho Ju-Han Kim

Recent reports about the excellent clinical results of unicondylar knee arthroplasty (UKA; also known as unicompartmental knee arthroplasty), by the minimally invasive approach, have encouraged the adoption of the surgical technique. However, friction between metallic prosthetic components resulting from polyethylene wear may result in the development of metallosis and the use of metal implants has become a huge issue in the worlds recently. Here, we report a case in which a patient underwent UKA and developed metallosis in soft tissues and bone adjacent to an implanted artificial joint three years postoperatively.


Full Access
Yoon Je Cho Joo-Hyun Lee Sangjoon Kwak Young Soo Chun Kee Hyung Rhyu Ye Yeon Won Myung-Chul Yoo

Purpose

There are some concerns about doing hip resurfacing arthroplasty in ONFH due to bone defect which can cause mechanical weakness of femoral component and highly active young age of patients which can cause high wear rate and failure rate. The purpose of this study is to verify the HRA is safe procedure in ONFH in the aspect of mechanical and biological issue.

Materials and Methods

Between December 1998 and May 2005, 185 hips of 169 patients underwent MoM HRA using Birmingham Hip Resurfacing System® at single center. 166 hips (26 hips of female, 140 hips of male) of 144 patients have been reviewed for at least 7 years after MoM HRA. Mean follow-up period was 101.8 (84–178) months. Their mean age at the time of operation was 37.7(16–67) years old. Clinically, Harris hip scores (HHS), UCLA activity scores and range of motion were evaluated. Radiologically, the extent of necrotic area in preoperative MRI and radiolucency around implants, narrowing of retained neck, impingement, stress shielding, and heterotopic ossification were evaluated in the serial anteroposterior and groin lateral radiographs of hip. Complications were defined as joint dislocation, infection, implant loosening, femoral neck fracture and pseudotumor. Failure was defined as revision arthroplasty due to the complications.


Woo-Shin Cho

Revision of infected TKA is one of the most challenging operation as the surgeon should achieve two goals, ie eradication of infection and restoration of function.

For the eradication of infection, a minimum of two operations are needed in most of cases.

First stage of revision is meticulous debridement and insertion of antibiotic loaded cement.

During arthrotomy, thick fibrous and granulation tissues which is located in the suprapatella pouch, lateral site to the patella tendon and posterior joint space should be removed so as to get better exposure, to get rid of infection source and to get better functional result.

During debridement, I use highly concentrated antibiotic saline (1 gm vancomycin in 10cc saline), for irrigation of the operation field. I also pack the opening of the medullary canal so as to prevent the debris from entering into the medullary canal.

I use antibiotics with the ratio of 1:3.

To reduce the dead space in the medullary canal I insert a dowel shaped antibiotic loaded cement spacer made from one pack of cement and fill the medullary canal. Thereafter two packs of cement are used to make a block to fill the gap between femur and tibia. The cement block should be large enough to cover the distal femur and proximal tibia so as not to cause bone defect and knee dislocation during walking.

After first stage of operation, antibiotics are administered for 4∼8 wks until the CRP levels become normalized and clinical findings show no sign of infection.

The 2nd stage of operation is planned when clinical and laboratory signs of infection subside. The decision whether to reimplant the prosthesis or not is based on the operation findings and polymorphonuclear cell count on frozen section. However operation findings are considered more important than the frozen section results for reimplantation.

If operative findings are clean, I do reimplanation even though the polymorphonuclear cell count is more than 5 on high power field(hpf) on frozen section.

I have adopted numbering system to take specimen. Number 1 is specimen from suprapatella pouch, No 2 is that from gap between the femur and tibia, No 3 is that from femoral intramedullary canal, No 4 is that from tibial intramedullary canal, and No 5 is that from most unhealthy site.

In a retrospective analysis of 16 cases which received reimplantation despite of the prescence of more than five polymorphonuclear cells on intra-operative frozen sections, none of the cases had recurrence of infection at a final follow up of 2 years. The femoral medullary canal was the most prevalent site for higher polymorphonuclear cell count.

In conclusion, indication is the first step for successful reimplantion. Two stage revision is recommended and meticulous debridement is utmost important in first stage operation. Block type antibiotic loaded cement is sufficient for a good result.

Clinical, laboratory and operative findings are more important than polymorphonuclear cell count on frozen section to decide reimplantation.

I propose numbering system of the specimen site for frozen section, just as in tumor surgery.


Won Yong Shon Dong Hun Suh Sung Kwang Chun

Introduction

Periprosthetic osteolysis following total hip arthroplasty is caused mainly by polyethylene wear particles and necessitates revision surgery at some stage even in the presence of well-fixed implants. Therefore, methods to estimate the polyethylene wear become important, with manual wear measurement methods as the main outcome measurement even in the presence of computer-assisted measurement methods on account of easy availability and simplicity in their use with reasonable accuracy. The purposes of this study were to quantify the accuracy and reproducibility of the slide presentation software method on clinical radiographs and to compare it with that of the previously described Livermore's method, and to determine the usefulness of the slide presentation software methods for highly cross linked polyethylene wear measurement.

Materials and Methods

81 hips out of 61 patients who underwent primary total hip arthroplasty between October 2000 and January 2006 were retrospectively evaluated for polyethylene wear by two independent observers using the Livermore's and the slide presentation software methods. All the hips were implanted with highly cross linked polyethylene acetabular liners with cementless acetabular components. The 28 mm sized cobalt chrome alloy femoral heads were used in all cases. The mean age of the patients was 50.8 years(range, 27–73 years), and the mean follow-up period was 6.6 years (range, 2–11 years). Paired radiographs were analyzed using the Livermore's and the slide presentation software method. For the Livermore's methods, radiographs were magnified to 200%, printed, and readings taken with digital calipers with an accuracy of 0.01 mm(Figure 1). For the slide presentation software method, we used Microsoft Office PowerPoint software(Microsoft Corp., Redmond, WA, USA) as described in a previous our study(Figure 2).


Phil Hyun Chung Suk Kang JongPil Kim Young Sung Kim Ho Min Lee

A seventy-five-year-old female patient presented with pain and deformity of her left leg of three days duration. Hybrid THRA has been done 11 years ago at her left hip for the treatment of osteoarthritis. Massive osteolysis and pathologic fracture were observed on plain radiograph (Fig. 1). Revision THRA using an allograft prosthesis composite (APC) was planned for solution of extensive bone loss of the proximal femur. Surgical exposure was performed through extended trochanteric osteotomy with the patient supine. Step-cut osteotomy was done at the remained proximal part of host femur to make match with the distal part of APC. Meticulous removal of granulation tissues and remaining cement was done. As Acetabular cup was stable, 60 mm sized high-walled polyethylene liner was exchanged. Calcar reconstruction prosthesis was cemented into a proximal femoral allograft measuring 15 cm and cement at the vicinity of the step-cut osteotomy was removed for later bony union at interface. After solid fixation of APC with cement, the distal half of APC was cemented with the host femur. Step-cut osteotomy was wired and autogenous bone grafts from the greater trochanter were added at the interface. Leg length and stability were rechecked using a standard necked 28 mm metal head and reduction was done stably. Greater trochanter was fixed over the trimmed proximal allograft with multiple wiring and paper-thin host femur was enveloped around the femoral allograft using absorbable sutures. Following insertion of the closed suction drainage drains, closure was done as routine fashion and healing of the wound was uneventful (Fig. 2). An abduction brace was applied post operatively for a period of four weeks. Crutch walking with partial weight bearing was started at four weeks and crutch protection was applied for a period of six months. Incorporation of allograft with the host bone was observed on two-year follow-up radiographs. At seven-year follow-up, the patient walks well with a mild limp, and Harris score is 90. We report on a seven-year follow-up case of revision THRA with APC with references (Fig. 3).


Henry Clarke Mark J Spangehl

Introduction

Patellar resurfacing during Total Knee Arthroplasty (TKA) is controversial. Problems unique to patellar resurfacing may be influenced by available patellar component design. These issues include; over-stuffing (the creation of a composite patellar-prosthesis thickness greater than the native patella) that may contribute to reduced range of motion; and over-resection of the native patellar bone that may contribute to post-operative fracture. Prosthesis design may play a role in contributing to these problems. Component diameter and thickness are quite variable from one manufacturer to another and little information has been previously published about optimal component dimensions. This anatomic study was performed to define the native patellar anatomy of patients undergoing TKA, in order to guide future component design.

Methods

This retrospective, IRB approved study reviewed 797 Caucasian knees that underwent primary TKA by a single surgeon. Data recorded for each patient included: gender; patellar thickness before and after resurfacing, and the size of the component that provided the greatest patellar coverage without any overhang. The residual patellar bone thickness after resection was also calculated.


Russell Cohen Nebojsa Skrepnik Jay Katz John Maltry Lawrence R Housman Scott Slagis Robert Eberle

The purpose of this study was to compare the clinical, radiographic, and DEXA results of Epoch® Femoral Component for primary THA with other non-cemented femoral components. The Epoch and Epoch 14+ (Zimmer, Warsaw, IN) Composite Femoral Components were studied in conjunction with the VerSys® Fiber Metal Taper, Fiber Metal Mid coat and Beaded Fullcoat Femoral Components (Zimmer, Warsaw, IN). All patients were randomized into one of five component groups and followed prospectively. All patients across the five groups were matched with respect to demographics and body mass index (BMI) (Table 1). Diagnoses were evenly distributed across all study groups. There was no significant change in BMD at 5-years when compared to the baseline (6 month) DEXA measurements for all component groups except for the Beaded Fullcoat component subset which had significant decreases in BMD in proximal zones 1, 6 and 7, The Fiber Metal Taper showed similar decreases in BMD in zones 1 and 7, and the Epoch Component had a significant decrease in BMD in zone 7 only. Additionally, our DEXA findings complement and support the subjective radiographic interpretations performed for this study cohort. The results from this prospective, randomized controlled clinical trial showed that the Epoch Composite Femoral Component for primary THA can achieve results equal to standard alloy components of varying design. Based on these early results, the Epoch and Epoch 14+ Femoral Components for primary THA are justified for continuance of further prospective study.


Russell Cohen

Modularity of femoral components has been widely accepted at the head neck junction, most commonly combining two unlike metals with only sporadic reporting of compatibility issues and corrosion. The development and introduction of a new and improved modular neck junction (Rejuvenate Modular Femoral component, Stryker Orthopedics) provided the option of fine-tuning leg lengths, offset and stability. The surgical technique did indeed provide the desired endpoints, however, the early recognition of problems with the junction causing corrosion and Adverse Local Soft Tissue Reaction (ALTR) and subsequent revision has led to the product being voluntarily withdrawn from the market. My experience as an early user of this stem is described in this manuscript providing a better early recognition and treatment of this potentially very destructive process.

Methods

A retrospective review of one hundred and ninety one Rejuvenate Stems that were implanted between January 2010 and January of 2012. However, after March 2011, this stem was only used on those patients who had a rejuvenate stem on the contralateral side. They were all implanted through a mini posterior incision with the first 82 patients receiving a Tritanium cluster hole cup (Stryker Orthopedics) with between two and three screws. The remaining 109 patients had an ADM (Anatomic Dual Mobility, Stryker Orthopedics). All patients were allowed to bear weight as tolerated and were followed up with Xrays at six weeks and one year. Clinical visits were recorded at 2 weeks and 6 months postop. Additional follow up was scheduled every two years following the first annual visit.

Results

One hundred and seventy four of the 191 hips were available for review at the one-year follow-up. Fourteen patients have undergone revision of the hip due to increased pain and formation of an avascular pseudo capsule due to corrosion at the neck stem junction. All patients have demonstrated a black flaky residue at the taper junction and all have had a large, tense effusion with a milky colored fluid. A neo caspsule has formed in all patients that appeared avascular and thickened. Seven of the eight tritanium cups in the revision cases were loose and required revision, while none of the ADM cups were loose. One patient has undergone two revisions since the initial cause of failure was not recognized and she subsequently developed pain within three months following placement of a new modular neck at the initial revision. One patient who underwent revision developed a deep infection and is currently on antibiotics but has not cleared the infection as of this writing.


Dermot Collopy Thies Wuestemann Amos Race Jim Nevelos

INTRODUCTION

Immediate post-operative stability of a cementless hip design is one of the key factors for osseointegration and therefore long-term success [1]. This study compared the initial stability of a novel, shortened, hip stem to a predicate standard tapered wedge stem design with good, long-term, clinical history. The novel stem is a shortened, flat tapered wedge stem design with a shape that was based on a bone morphology study of 556 CT scans to better fit a wide array of bone types [2].

METHODS

Test methods were based on a previous study [3]. Five stems of the standard tapered wedge design (Accolade, Stryker Orthopaedics, Mahwah, NJ) and the novel stem (Accolade II, Stryker Orthopaedics, Mahwah, NJ) were implanted into a homogenous set of 10 synthetic femora (Figure 1) utilizing large left fourth generation

composite femurs (Sawbones, Pacific Labs, Seattle, WA). The six degrees-of-freedom (6 DoF) motions of the implanted stems were recorded under short-cycle stair-climbing loads. Minimum head load was 0.15 kN and the maximum load varied between 3x Body Weights (BW) and 6 BW. Loading began with 100-cycles of “normal” 3 BW and was stepped up to 4 BW, 5 BW & 6 BW for 50-cycles each. Prior to each load increase, 50 cycles of 3 BW loading was applied. This strategy allowed a repeatable measure of cyclic stability after each higher load was applied.

The 6 DoF micromotion data, acquired during the repeated 3 BW loading segments, were reduced to four outcome measures: two stem migrations (retroversion and subsidence at minimum load) and two cyclic motions (cyclic retroversion and cyclic subsidence). Data were analyzed using repeated measures ANOVA with a single between-subjects factor (stem type) and repeated measures defined by load-step (3 BW, 4 BW, 5 BW 6 BW).


Matthew Colman Lisa Choi Antonia Chen Peter Siska Mark Goodman Lawrence S Crossett Ivan Tarkin Richard McGough

Objectives

To examine patient mortality, implant survivorship, and complication profiles of proximal femoral replacement (PFR) as compared to revision total hip arthroplasty (REV) or open reduction internal fixation (ORIF) in the treatment of acute periprosthetic fractures of the proximal femur.

Methods

We performed a retrospective controlled chart review at our tertiary center from from 2000–2010, identifying 97 consecutive acute periprosthetic proximal femoral fractures. Patients were stratified into three treatment groups: PFR (n=21), REV (n=19), and ORIF (n=57). Primary outcome measures included death, implant failure, and reoperation. We also recorded patient demographics, medical comorbidities, fracture type, treatment duration, time to treatment, and complication profiles. Statistical analyis included competing risks survival, which allows independent survival analysis of competing failure mechanisms such as death and implant failure.


Michael Conditt Sharon H Branch Michael Ballash Carinne Granchi

INTRODUCTION

Adult reconstructive orthopedic surgery in the United States is facing an imminent logjam due to the increasing divergence of the demand for services and the ability for the community to supply those services. In combination with several other factors, a perfect storm is brewing that may leave the system overtaxed and the patient population suffering from either a lack of treatment, or treatment by less qualified providers. A key component to improving the overall efficiency of surgical care is to introduce enabling technologies that can effectively increase the throughput while simultaneously improving the quality of care. One such enabling technology that has proven itself in many industries is robotics, which has recently been introduced in surgery with even more recent applications in orthopedic surgery. A surgeon interactive robotic arm has been developed for partial knee arthroplasty (PKA) and total hip arthroplasty (THA). This study aims to analyse the efficiency of a new robotic technology for use in orthopaedic surgery.

METHODS

18 robotic arm assisted PKA's across 10 sites were recorded to accurately capture the timeline elemental tasks throughout the procedure. Two camera angles were set up to capture both surgical staff group dynamics and individual procedural steps. 17 tasks were identified and measured from video data. (Fig 1) The robotic arm specific tasks were analyzed for correlation to total surgical time (measured as first incision to last suture). The tasks for the surgeons with the shortest and longest total times were compared directly to determine areas of opportunity.


Benjamin Domb Zachary Finley Ryan Baise Itamar Botser Michael Conditt

Introduction

Improper acetabular component orientation has been shown to negatively affect the outcome of total hip arthroplasty through increasing dislocation rates, component impingement, bearing surface wear, and the rate of revision surgeries. The “Safe Zone” was defined by Lewinnek et al. in 1978 as 5 to 25 degrees of cup version and 30 to 50 degrees of cup inclination. Later, the inclination “Safe Zone” values were modified to 30 to 45 degrees.

Objectives

The primary purpose of this study was to assess whether the use of Mako robotic hip system improves cup positioning when compared to traditional THR.


Joseph Daniel Hena Ziaee Chandra Pradhan Derek McMinn

Introduction

Large diameter metal-on-metal hip arthroplasty (LDMMTHA) provides benefits of reduced dislocation rates and low wear. The use of modular systems allows better restoration of hip biomechanics. There have been reports of modular LDMMTHAs with tapered sleeves generating excessively high metal ions, due to possible mismatch between the titanium stem and the cobalt-chrome sleeve and the dual Morse tapers involved. We evaluated metal ion levels in LDMMTHA patients with and without a cobalt-chrome (CoCr) tapered sleeve.

Methods

A cross-sectional series of 91 patients with proximal porous titanium alloy stem LDMMTHA with identical design CoCr bearings, attending a 1 to 2-year review were assessed with routine clinical and radiographic examinations, hip scores and metal ion analysis. Of these 65 had a single Morse taper between monoblock CoCr heads and the stems. Twentysix had a tapered cobalt-chrome sleeve in addition, with the resultant dual taper. Mean bearing diameter was 46 mm in both groups and mean age was 58 years in the monoblocks and 66 years in the tapered sleeve group.


Joseph Daniel Chandra Pradhan Hena Ziaee Derek McMinn

Introduction

High early failure rates have been reported with certain metal-metal surface arthroplasties and good results have been reported with others. This is a minimum 10-year review of the first 1000 consecutive resurfacings including all ages and diagnoses from one centre.

Methods

The first 1000 surface arthroplasties (892 patients) were followed-up with postal questionnaires. Of these the first 402 hips (350 patients) were also invited for a clinico-radiological review. 54 patients (63 hips) died 6.7 years (0.7–12.6) later due to unrelated causes. Mean follow-up is 12.2 years (range 10.8–13.7). Radiographs were assessed independently by a senior musculoskeletal radiologist.


Chandra Pradhan Joseph Daniel Hena Ziaee Derek McMinn

Introduction

This is a retrospective review of the incidence of deep venous thrombosis (DVT) in 679 consecutive unilateral primary hip arthroplasty procedures performed between January 2007 and December 2010 managed with no anticoagulants. Mean age at operation was 58 years. Mean BMI was 26. The prophylaxis regimen included hypotensive epidural anesthesia, compression stockings, intermittent calf compression, early mobilization and an antiplatelet agent.

Methods

562 hybrid hip resurfacing procedures and 117 uncemented THRs, all performed through a posterior incision were included. Doppler ultrasound screening for DVT was performed in all patients between the fourth and sixth post-operative days. Patients were reviewed clinicoradiologically 6 to 10 weeks after operation and with a postal questionnaire at the end of 12 weeks to detect symptomatic VTE incidence following discharge. 14 patients with pre-existent VTE, coagulation disorders or cardiac problems requiring anticoagulant usage were excluded.


Carlo Felice De Biase Marco Delcogliano Mario Borroni Stefano Gumina Franco Postacchini Alessandro Castagna

Introduction

the aim of the study is to evaluate the clinical results of the shoulder prosthesis revision procedure to reverse implant without removing the humeral stem using a modular system (Lima LTD) and determine if this procedure is beneficial for the patients.

Methods

e selected only the patients where a revision to reverse (RSA) of hemiarthroplasty (Hemi) originally implanted for fracture (Group I) and revision to reverse (RSA) of anatomical total prosthesis (TSA) were performed. From 2004 to 2009 26 cases responding to these parameters were identified: 18 cases in Group I (failed hemiarthroplasty for tuberosities resorptions or rotator cuff failure) and 8 in Group II (failed TSA for rotator cuff omplication).

The mean follow-up was 32 months (min 18–max 76) and the mean age was 72 (min 65–max 80)

Clinical assessment was performed with preoperative and postoperative Constant score rating scale (CS) and range of motion evaluation (ROM)

Radiological assessment was performer by AP and Axial X-ray views. Operative time was calculated.


Thibaut De Bock Sumesh Zingde Filip Leszko Ray Tesner Ray Wasielewski Mohamed Mahfouz Richard Komistek

Introduction

The low-cost, no-harm conditions associated with vibroarthography, the study of listening to the vibrations and sound patterns of interaction at the human joints, has made this method a promising tool for diagnosing joint pathologies. This current study focuses on the knee joint and aims to synchronize computational models with vibroarthographic signals via a comprehensive graphical user interface (GUI) to find correlations between kinematics, vibration signals, and joint pathologies. This GUI is the first of its kind to synchronize computational models with vibroarthographic signals and gives researchers a new advantage of analyzing kinematics, vibration signals, and pathologies simultaneously in an easy-to-use software environment.

Methods

The GUI (Figure 1) has the option to view live or previously captured fluoroscopic videos, the corresponding computational model, and/or the pre- or post-processed vibration signals. Having more than one signal axes available allows for comparison of different filtering techniques to the same signal, or comparison of signals coming from different sensor placements (ex: medial vs. lateral femoral condyle). Using computational models derived using fluoroscopic data synchronized with the vibration signals, the areas of contact between articulating surfaces can be mapped for the in vivo signal (figure 2). This new method gives the opportunity to find correlations between the different sensor signals and contact maps with the diagnosis and cartilage degeneration map, provided by a surgeon, during arthroscopy or TKA implantation (figure 3).


Thibaut De Bock Galina Orekhov Stefon Stephens Douglas Dennis Mohamed Mahfouz Richard Komistek

Introduction

Previous fluoroscopy studies have been conducted on numerous primary-type TKA, but minimal in vivo data has been documented for subjects implanted with revision TKA. If a subject requires a revision TKA, most often the ligament structures at the knee are compromised and stability of the joint is of great concern. In this present study, subjects implanted with a fixed or mobile bearing TC3 TKA are analyzed to determine if either provides the patient with a significant kinematic advantage.

Methods

Ten subjects are analyzed implanted with fixed bearing PFC TC3 TKA and 10 subjects with a mobile bearing PFC TC3 TKA. Each subject underwent a fluoroscopic analysis during four weight bearing activities: deep knee bend (DKB), chair rise, gait, and stair descent. Fluoroscopic images were taken in the sagittal plane at 10 degree increments for the DKB, 30 degree increments for chair rise, and at heel strike, toe off, 33% and 66% cycle gait and stair descent.


Daniel C.J. De Kam Moniek R.J. Van Heumen Jean W.M. Gardeniers Rene P.H. Veth B. Willem Schreurs

Background

These days, total hip arthroplasties (THA) are more implanted in young patients. Due to the expected lifespan of a THA and the life expectancy of young patients, a future revision is inevitable. Indirectly increasing the number of revisions in these patients. Therefore we evaluated the results of revision THA in patients under the age of 60 years. However, we used a unique protocol in which we used in all cases of acetabular and/or femoral bone deficiencies reconstruction with bone impaction grafting.

Methods

To determine the mid- to longterm results of cemented revision total hip arthroplasties in patients under the age of 60, all clinical data and radiographs were analyzed of patients operated between 1992 and 2005. Patients with multiple previous revisions were also included. Only cemented components were used. During this period 146 consecutive revision total hip arthroplasties were implanted in 129 patients. This included 124 cup and 106 stem revisions. The average age at index surgery was 47 years. No case was lost. Mean follow-up was 7.6 (range, 2.0–16.7) years.


Bernard Devadasan

Mini-incision total hip arthroplasty seeks to eliminate some complications of traditional extensile exposure and also facilitates more rapid post-operative rehabilitation. Posterior approach has been associated with increased risk of posterior dislocation. Thus, a modified mini-incision lateral approach of Hardinge was described not only to overcome this problem by preserving the posterior capsule, but also allows adequate access for orientation of the implant. The author has modified the Hardinge approach by a V-shaped incision where the apex is centered over the tip of the greater trochanter with the one limb extending proximally along the fibers of the gluteus medius muscle and the distal limb extending across the proximal part of vastus lateralis. This innovative surgical approach is described in this article.

Conclusion

Larger incisions and surgical approaches have been associated with larger blood loss, greater need for perioperative transfusion, use of more postoperative analgesics, a longer hospital stay, and a slower recovery. In this modified approach, the gluteus medius is left intact. The postoperative strength of the abductors of the operated side was the same as that on the non-operated side and functionally, the direct lateral approach was a safe alternative to other approaches in decreasing the trendelenburg gait and incidence of heterotrophic ossification.


Angelo Di Giunta Alfonso M. Romano Massimiliano Susanna Zappia Marcello

Introduction

The following study start from an idea of the evaluation of the osteointegration in the bone cage of the Equinoxe Reverse shoulder prosthesis.

The aim of the study is to assess the values of Bone Mineral Density (BMD) in periprosthetic areas, in patients undergoing shoulder arthroplasty with implants of the Equinoxe system by Excatech, Inc.

To better understand the steps of osteointegration time of the bone cage with the glenoid

The objectives of the work are not only expanded to the value of osteointegration, but could also be useful for the evaluation of both mechanical and septic loosening of the stem of the glenoid.

Materials and Methods

In the period from November 2011 to May 2012, 15 patients were evaluated.

All patients were subjected to bone densitometry type of DXA within the first 15 days after surgery and at 3 months after surgery.

The patients are all part of a homogeneous group for anatomical glenoid

Were excluded from the study all patients who were no significant alterations of the head and the glenoid.

The acquisitions were performed with the patient in an oblique position, with limb in a neutral position, in order to obtain images in the coronal plane “true” of the joint.

Were subsequently calculated values of BMD is around the stem with the 7 areas used by Gruen for the hip prosthesis and peripherally to the central peg using 3 areas, superiorly, medially and inferiorly to the same.


Jonathan Netter Juan Hermida Mark Kester Jerry D'Alessio Nikolai Steklov Cesar Flores-Hernandez Clifford Colwell Darryl D Lima

INTRODUCTION

Wear and polyethylene damage have been implicated in up to 22% of revision surgeries after unicompartmental knee replacement. Two major design rationales to reduce this rate involve either geometry and/or material strategies. Geometric options involve highly congruent mobile bearings with large contact areas; or moderately conforming fixed bearings to prevent bearing dislocation and reduce back-side wear, while material changes involve use of highly crosslinked polyethylene. This study was designed to determine if a highly crosslinked fixed-bearing design would increase wear resistance.

METHODS

Gravimetric wear rates were measured for two unicompartmental implant designs: Oxford unicompartmental (Biomet) and Triathlon X3 PKR (Stryker) on a knee wear simulator (AMTI) using the ISO-recommended standard. The Oxford design had a highly conforming mobile bearing of compression molded Polyethylene (Arcom). The Triathlon PKR had a moderately conforming fixed bearing of sequentially crosslinked Polyethylene (X3).

A finite element model of the AMTI wear simulation was constructed to replicate experimental conditions and to compute wear. This approach was validated using experimental results from previous studies.

The wear coefficient obtained previously for radiation-sterilized low crosslinked polyethylene was used to predict wear in Oxford components. The wear coefficient obtained for highly crosslinked polyethylene was used to predict wear in Triathlon X3 PKR components. To study the effect design and polyethylene crosslinking, wear rates were computed for each design using both wear coefficients.


Christopher Drinkwater Arash Kermanshahi Matthew Brown

Introduction

We acquired an optical tracking navigation system for Total Hip Arthroplasty. We compare cup positioning and other operative factors along with clinical results using navigated and non-navigated techniques in a series of 341 Total Hip Arthroplasties.

Method

This is a retrospective review of consecutive patients from November 2005 through December 2010, including 126 cases of imageless computer assisted total hip replacement and 215 cases of standard total hip replacement. We analyzed operative time, blood loss, leg length discrepancy, acetabular component inclination, complications, Harris Hip scores and performed a cost analysis. Follow-up was from 3–64 months. All cases were performed by or under the supervision of a single surgeon. Digital AP pelvic radiographs centered on hips were used for measurements. Radiographic results were averaged based on three individual measurements. Statistics required the student t-Test.


Christopher Drinkwater Wes Madsen Matthew Brown

Hypothesis

Custom cutting blocks can produce similar alignment compared to computer navigated and conventional total knee arthroplasty (TKA) techniques.

Method

We conducted a retrospective review of 37 patients who underwent TKA by a single surgeon in a teaching hospital setting. Groups were conventional method (10), computer assisted navigation (10), and custom blocks (18). The custom group was further subdivided to CT and MRI based blocks. Post-operative alignment was measured (blinded) using full length weight bearing radiographs at 18 weeks on average. Hospital records were reviewed to determine operative time, transfusion requirements, length of hospital stay, complications and cost.


Christina Esposito Anne Roques Mike Tuke Bernard Zicat William K Walter William Walsh William L Walter

Introduction

Edge loading commonly occurs in all bearings in hip arthroplasty. Edge loading wear can occur in these bearings when the biomechanical loading axis reaches the edge and the femoral head loads the edge of the cup producing wear damage on both the head and cup edge. When the biomechanical loading axis passes through the polished articulating surface of the acetabular component and does not reach the edge, the center of the head and the center of the cup are concentric. The resulting wear known as concentric wear is low in metal-on-metal (MOM) bearings, and is negligible in ceramic-on-ceramic (COC) bearings. Edge loading is well defined in COC hip bearings. However, edge loading is difficult to identify in MOM bearings, since the metal bearing surfaces do not show wear patterns macroscopically. The aims of this study are to compare edge loading wear rates in COC and MOM bearings, and to relate edge loading to clinical complications.

Materials and Methods

Twenty-nine failed large diameter metal-on-metal hip bearings (17 total hips, 12 resurfacings) were compared to 54 failed alumina-on-alumina bearings collected from 1998 to 2011. Most COC bearings were revised for aseptic loosening or periprosthetic bone fracture, while most MOM bearings were revised for pain, soft tissue reactions or impingement. The median time to revision was 3.2 years for the metal hip bearings and 3.5 years for alumina hip bearings. The surface topography of the femoral heads was measured using a RedLux AHP (Artificial Hip Profiler, RedLux Ltd, Southampton, UK).


Christina Esposito Rema Oliver Pat Campbell William K Walter William L Walter William Walsh

In patients with conventional metal-on-Polyethylene (MoP) hip replacements, osteolysis can occur in response to wear debris. During revision hip surgery, surgeons usually remove the source of osteolysis (polyethylene) but cannot always remove all of the inflammatory granulomatous tissues in the joint. We used a human/rat xenograft model to evaluate the effects of polyethylene granuloma tissues on bone healing. Human osteoarthritic and periprosthetic tissues collected during primary and revision hip arthroplasty surgeries were transplanted into the distal femora of athymic (nude) rats. The tissues were assessed before and after implantation and the bone response to the tissues was evaluated after 1 week and 3 weeks using micro-computed tomography, histology, and immunohistochemistry. After 3 weeks, the majority (70%) of defects filled with osteoarthritic tissues healed, while only 21% of defects with polyethylene granuloma tissues healed. Polyethylene granuloma tissues in trabecular bone defects inhibited bone healing. Surgeons should remove polyethylene granuloma tissues during revision surgery when possible, since these tissues may slow bone healing around a newly implanted prosthesis. This model provides a method for delivering clinically relevant sized particles into an in vivo model for investigation.


LaQuawn Loving Lizeth Herrera Reginald Lee Aaron Essner

The dual mobility hip incorporates a femoral head mated within a spherical polyethylene liner which also has an unconstrained outer articulation with a polished metal shell. An additional wear surface is introduced at the outer articulation, however, the mobility of the polyethylene insert does allow for femoral-neck/acetabular-insert impingement by allowing the insert to displace upon contact. We evaluated the wear performance of a dual mobility hip during abrasive and impingement conditions independently. Three abrasive conditions were evaluated; abraded acetabular cup, abraded femoral head, and both abraded cup and head. Two impingement conditions were evaluated; impingement of the unconstrained acetabular insert against the femoral neck, and acetabular-insert/femoral-neck impingement when the insert becomes immobilized at the outer articulation.

Wear testing was conducted using a hip stimulator. The simulator applied physiologic loading with a maximum load of 2450 N and serum as the lubricant. Components were abraded at the pole according to a published method. Abraded samples were tested at 0° of inclination. The unconstrained impingement condition was created by adjusting the femoral neck angle to achieve impingement with 45° of acetabular inclination. Neck to liner impingement can occur at either the superior or inferior surface of the femoral neck, with subsequent impingement occurring randomly as the insert is allowed to re-align itself throughout testing. The fixed impingement conditions was created by locking the outer bearing through fixturing and inducing impingement as previously described. Dual mobility control components were tested at 0° and 50° of inclination. Inserts were sequentially crosslinked GUR 1020 polyethylene.

Results are shown in Figure 1. Abrasion testing results correlated to a combination of friction at the abraded articulation and bearing size. Abrasion at only the inner bearing had a larger effect on wear when compared to abrasion of only the outer bearing. When both sides were damaged, femoral head abrasion led to an increase in friction and resistance to movement at the inner articulation, thereby forcing an increase in overall movement of the outer articulation. This increased the contact area subject to motion across a scratched metal surface, which increased the wear rate of the system. Unconstrained impingement samples impinged during the first cycle and then randomly throughout testing, while the fixed impingement samples had predictable impingement at the same location every cycle of testing. The unconstrained impingement model was designed to replicate an instance where the dual mobility hip would run in a near/intermittent impingement condition where the polyethylene insert displaces upon contact with the femoral neck. Unconstrained impingement wear rates were not statistically different than the ideally aligned control. The fixed impingement samples wore at a higher rate than the unconstrained impingement and control groups. The insert encountered resistance to movement upon impingement resulting in wear and deformation at the point of contact. Additional intended bearing wear was also generated by head sliding and translation of the load path upon impingement of the rim. Note that this condition is difficult to envision clinically and all wear rates, even under adverse conditions, were acceptably low.


Sang Soo Eun Woo Chun Lee Sang Ho Lee Young Il Hwang

The purpose of this study was to obtain anatomical measurements of the distal tibia and talus of Korean ankles and to evaluate, based on those measurements, the compatibility of the HINTEGRA prostheses in the context of total ankle replacement (TAR). We measured the length, width, height, and angles of the distal tibia and talus of 51 cadavers and compared these measurements with the corresponding dimensions of the HINTEGRA prostheses. The male ankles were larger than the female ones as was expected, but their overall shapes did not differ, which fact validates use of the prostheses irrespective of patients' sex. The dimensions of the talus itself did not differ significantly from those previously reported for American whites and blacks and South African whites. This might suggest a possibility that the HINTEGRA prostheses, being used in these countries, would be compatible to Korean ankles, too. In fact, the length range of the talar components was generally compatible with those derived from cadaveric measurements of the trochlea. However, the widths of the tibial and talar components were not completely compatible to Korean ankles. Above all, the length of the large-sized tibial components was much longer than the largest ankles, which would confine the choice of prosthesis mainly to small-sized ones for arthroplasty in Korea. Even though these prostheses are currently used, some modifications are needed to extend their usability in Korea, such as shortening and width/length ratio adjustment of the tibial component, and of the talar component accordingly.


Rajnish Garg Mohammad Yamin Pankaj Mahindra Sudhanshu Nandra

Primary Total Knee Arthroplasty (TKA) is considered to be one of the most successful orthopedic surgical interventions performed. Long-term results have been generally excellent, with 10–15 year survival rates as high as 90–95% reported, few complications, and reoperations occurring in approximately one percent of patients per year. One of the most important outcome measures of TKA is the range of motion. It has been demonstrated that a 67° of knee flexion is needed for the swing phase of the gait, 83° to climb stairs, 90° to descend stairs, and 93° to rise from chair.

This is a prospective study of 50 patients who underwent Total Knee Arthroplasty at Dayanand Medical College & Hospital, Ludhiana between March 2008 & April 2009. Patients with a primary diagnosis of osteoarthritis, rheumatoid arthritis, or traumatic arthritis in which Natural Knee II implant (Zimmer) was used were included in the study. Absolute exclusion criteria were infection, sepsis, osteomyelitis, revision of a previous total knee replacement or deformities of the hip and spine. Preoperative demographic data, including sex, age at surgery, side affected, body mass index, primary diagnosis, tibio-femoral angle, knee score and functional score, and preoperative passive ROM were obtained. Patients underwent a medial parapatellar approach, with cement used to fix both the femoral and tibial components. Patellar resurfacing was not performed. Following surgery, patients underwent physical therapy at home or in a physiotherapy center, as appropriate. ROM and flexion were calculated at three and six months postoperatively.

54% of the patients were of age 60–75 years and 70% of them were females. 92% patients suffered from osteoarthritis. 80% patients had a BMI of <30 points. 63.46% patients had a preoperative knee flexion of <90°. The average preoperative knee flexion improved from 94.94° to 107.21° at 3 months and 112.12° at 6 months postoperatively (p-value=0.000056). The average preoperative knee flexion in patients with preoperative knee flexion <90°, 90°–110° and >110° changed from 88.33°-106.36°-108.73°, 102.67°-108.33°-114° and 120.50°-110°-117.50° at 3 months and 6 months respectively. The average preoperative knee score was 46.55 and functional score was 50.30, which improved to 95.62 (p-value=0.000015) and 75.60 (p-value=0.000213) respectively.

Postoperative ROM is a function of many factors, with preoperative ROM being one of the most important. The knee ROM tends to regress towards a mean with excellent preoperative ROM loosing and poor preoperative ROM improving. Several factors related to surgical techniques have been found to be important. These include the tightness of the retained posterior cruciate ligament, the elevation of the joint line, increased patellar thickness, and a trapezoidal flexion gap. Vigorous rehabilitation after surgery appears useful, while continuous passive motion has not been found to be effective. Obesity and previous surgery are poor prognostic factors. In general, the clinical results of TKA were satisfactory in terms of pain relief and overall function. It was found that measurement of preoperative flexion gives the surgeon a good parameter for predicting flexion after arthroplasty.


Noam Gavriely

Introduction & Aims

Mild to moderate CD after TKA is a common side-effect of an otherwise successful procedure. Despite improvement in the majority of the cases within weeks to a few months, this is a source of concern and disappointment. This analysis presents a possible mechanism for post-TKA cognitive changes.

Method

We reviewed the literature on the hemodynamic events around limb exsanguination, tourniquet placement and release during TKA. The majority of this literature is in anesthesia journals, with only a few in orthopedic journals (e.g., Berman, JBJS, 1998, 389–96). Once the data was collected, we scrutinized it for validity and in order to identify a plausible etiology that links between the TKA operating procedure and CD.


Thomas Gross Fei Liu

761 cases in 613 patients with minimal two years follow-up had both metal ion levels and quality pelvis X-ray identified in our database and are included in this study. The UCLA activity score, femoral shaft angle, body mass index, weight, American Society of Anesthesiologists (ASA) score, combined range of motion (CROM), diagnosis, age, implant brand, gender, AIA, bearing size, and duration of implantation were analyzed to determine the potential risk factors for elevated metal ion levels with use of uni- and multi-variable logistic regression models. A safe zone for hip resurfacing (RAIL: Relative Acetabular Inclination Limit) was calculated based on implant size and AIA on AP pelvis X-ray. For AIA below the RAIL, there were no adverse wear failures or dislocations, and only 1% of cases with ion levels above 10 μg/L. We have not found a lower limit of AIA where failures occurred. Other than high inclination angle and small bearing size, female gender was the only other factor that correlated with high ion levels in the multivariate analysis. We have described the robust “safe zone” for acetabular component position based on metal ion levels in a large patient cohort for metal-on-metal hip resurfacing arthroplasty. Our study suggests that adverse wear failures with hip resurfacing may be highly predictable and avoidable. If the AIA is below the RAIL, rare dislocations are also prevented.


Benjamin McArthur Matthew Grosso Brian Michaels David J Mayman

Introduction

Traditional methods of component positioning in total hip replacement (THR) utilize mechanical alignment guides which estimate position relative to the plane of the operating room table. However, variations in pelvic tilt alter the relationship between the anatomic plane of the pelvis and that of the table such that components placed in optimal position relative the table may not land within the classic anatomic “safe zone” described by Lewinnek. It has been suggested that navigation software should incorporate adjustments for the degree of pelvic tilt. Current imageless navigation software has this capability, however there is a paucity of data regarding the accuracy of this technology.

Purpose

We aimed to assess the accuracy of intra-operative pelvic tilt adjusted anteversion measurements as compared to unadjusted measurements.


Sulaiman Alazzawi Fares Haddad

Introduction

Acute infection following Total Hip Arthroplasty (THA) is a serious complication. It is commonly treated by irrigation and debridement (I&D) with component retention (exchange only the mobile parts of the joint - head and liner). However, the reported re-infection rate with the use of this approach remains high. We are reporting our experience in using single - stage revision arthroplasty in treating acute infection of THA. We hypothesized that the infection control rate after immediate early revision for acute infection of cementless implants is better than has been reported for I&D with exchange of mobile parts.

Methods

From our infection arthroplasty database, we reviewed the outcome of 19 patients who had an acute infection (within 6 weeks) of cementless THA. Our management strategy includes I&D and single-stage (direct-exchange) revision arthroplasty followed by 6 weeks course of culture specific oral antibiotics.


Shivan Jassim Nick Marson Harry Benjamin-Laing Stephen Douglas Fares Haddad

Introduction

Technology in Orthopaedic surgery has become more widespread in the past 20 years, with emerging evidence of its benefits in arthroplasty. Although patients are aware of benefits of conventional joint replacement, little is known on patients' knowledge of the prevalence, benefits or drawbacks of surgery involving navigation or robotic systems.

Materials & Methods

In an outpatient arthroplasty clinic, 100 consecutive patients were approached and given questionnaires to assess their knowledge of Navigation and Robotics in Orthopaedic surgery. Participation in the survey was voluntary.


Mahmoud Hafez Ismail Rashad

Recently, a new technique of custom-made cutting guides for TKA is introduced to clinical practice. However, no published data yet on the comparison between this new technique against both navigation and conventional techniques.

The author prospectively compared between custom-made cutting guides, navigation and conventional techniques. A total number of 90 cases were included in this study with 30 consecutive cases for each technique. The highest number of medically unfit patients and those with articular and extra articular deformities were in custom guides groups.

The results showed one case of aseptic loosening after one year in custom guides, one case of superficial infection and loose pins but with no fracture in navigation group, and higher need for blood transfusion in conventional. One case in the custom guide group had a periprosthetic fracture 3 weeks postoperatively diagnosed as insufficiency fracture after a relatively minor trauma to an osteoporotic bone. Navigation was the most accurate in alignment but custom guides was the most accurate in implant sizing and had the least bleeding.

This clinical study showed some advantages of custom-made cutting guides over conventional instrumentation. It eliminated medullary guides, reduced operative time, and provided better accuracy. The technique was proved to be useful in complex cases of deformities and unfit patients.


William Hamel

A Tracking Fluoroscope System (TFS), the first of its kind, has been developed and the design of this new technology has been previously presented. The TFS is a unique mobile robot that can acquire real-time x-ray records of hip, knee, or ankle joint motion while a subject walks/maneuvers naturally within a laboratory floor area. By virtue of its mechanizations, test protocols can involve many types maneuvers such as chair rises, stair climbing/descending, ramp crossing, walking, etc. Because the subjects are performing such actions naturally, the resulting fluoroscope images reflect the full functionality of their musculoskeletal anatomy. The goal of this follow-up study is to conduct a comparative analysis with traditional stationary fluoroscopy units to determine if this new technology does offer clinical and research advantages.

Technical trials with human subjects and active fluoroscope operation were designed to evaluate and refine the TFS engineering and operational features. These trials have been completed and the key results were compared with the traditional stationary fluoroscopic units. The technical trials verified that the TFS is ready for actual clinical diagnostic use and provides the researcher an opportunity to evaluate in vivo kinematics of subjects while performing normal daily activities at various speeds. Using the mobile fluoroscopic unit, patients performed activities that were not possible to capture with a stationary unit. Also, with the upgrade to an image recording rate of 60 frames per second, the quality of the fluoroscopic images using the TFS were superior to stationary units.

Further analyses are now being conducted to compare the kinematic results for a deep knee bend and gait, traditionally analyzed in the past using stationary fluoroscopic units to determine if there are unique advantages. It is hypothesized that the more normal-like gait patterns may produce kinematic patterns that differ from stationary fluoroscopic units. At present, the TFS has proven to be superior over other fluoroscopic units and will allow clinicians to evaluate patients under and unrestricted kinematic environment. Also, future research studies will be able to compare patients with or without a TKA under more challenging kinematic conditions, producing kinematic patterns that may lead to incites pertaining to TKA failure and/or concerns.


Shunji Hirokawa Michihiko Fukunaga Kazuo Kiguchi

We have developed a novel knee simulator that reproduces the active knee motion to evaluate kinematics and joint reaction forces of TKA.

There have been developed many kinds of knee simulators; Most of them are to predict TKA component wear and the others are to evaluate the kinematics and/or kinetics of TKA. The most simulators have been operated using the data of the loading and kinematics profile of the knee obtained from normal gait. Here a problem is that such variables as joint force and kinematics are the outcome caused by the application of muscles' and external forces. If so, a simulator should be operated by the muscles' and external forces so as to duplicate the in vivo condition. Other disadvantages for the current knee simulators are; a knee joint motion is made passively, the effects of the hip joint motion are not taken into account, and the maximum flexion angle is usually limited at about 100°.

Considering the above, we have developed a knee simulator with the following advantages and innovative features. First, the simulator is driven by the muscles' forces and an active knee motion is made with bearing the upper body weight. As a result, the knee shows a 3D kinematics and generates the tibio-femoral contact forces. Under this condition, the TKA performance is to be assessed. Secondly, a hip joint mechanism is also incorporated into the simulator. The lower limb motion is achieved by the synergistic function between the hip and knee joints. Under this condition, a natural knee motion is to be reproduced. Thirdly, the simulator can make complete deep knee flexion up to 180°. Thus not only the conventional TKA but also a new TKA for high flexion can be attached to it for the evaluation.

Figure 1 shows the structure of the simulator, in which both the hip and knee joints are moved in a synergistic fashion by the pull forces of four wires. The four wires are pulled by the four servomotors respectively and reproduce the functions of the mono-articular muscles ((1), (3)) and the bi-articular muscles ((2), (4)) through the multiple pulley system. It should be noted that weight A and B are not heavy enough for the inverted double pendulum to stand up straight. They are applied as counter weights so that each segment duplicate the each segmental weight of the human lower limb. Figure 2 shows a sequential representation of stand to sit features: (a) at standing, (b) at high flexion, and (c) at deep flexion. At a state of 130° knee flexion between (b) and (c), hamstrings wire (4) becomes shortest and then exhibits an eccentric contraction, thereby attaining deep flexion.

Our knee simulator can be a useful tool for the evaluation of TKA performance and may potentially substitute the in vivo experiments.


Donald Howie Susan Pannach Jochen Hofstaetter Margaret McGee David Shaw Stuart Callary Lucian Solomon

Introduction

To evaluate the clinical success and hip pain and function of patients with infected hip replacement treated by two-stage exchange using a temporary implant with high dose vancomycin added to the antibiotic cement at the first stage revision.

Method

Thirty-three hips in 32 patients (median 67 yrs) underwent first stage revision using the PROSTALAC™ system (n=27) or a self-made system using an Elite long stem (n=6). Infection was diagnosed after 19 primary, 11 revision and 3 hemiarthroplasty hip replacements. Patients were reviewed regularly clinically and by questionnaire. The median follow-up was 3 years.


Donald Howie Oksana Holubowycz Susan Neale Stuart Callary Lucian Solomon

Introduction

There has been almost universal adoption of highly cross-linked polyethylene as the polyethylene of choice in metal-on-polyethylene articulations in total hip replacement (THR). Although wear of conventional polyethylene has been shown to be related to periprosthetic osteolysis, the relationship between wear of highly cross-linked polyethylene and osteolysis remains uncertain. Our aim was to determine the incidence and volume of periacetabular osteolysis at a minimum of seven years following primary THR with metal on highly cross-linked polyethylene articulations.

Methods

644 patients were enrolled into a randomised controlled trial which examined the effect of articulation size (28 vs 36 mm) on the incidence of dislocation one year following THR. To date, 62 patients (34 patients – 28 mm articulation; 28 patients – 36 mm articulation) have undergone a quantitative computed tomography (CT) scan, with metal artefact reduction protocol, to detect and measure osteolysis at a minimum of seven years following THR. Osteolysis was defined as a localised area of bone loss of at least 1 cm3 that is expansile, with a well-defined sclerotic border, a clear communication between the defect and the joint space and the absence of acetabular cysts. Pre-operative and post-operative plain radiographs were examined to identify the existence of acetabular cysts. Polyethylene wear from one to seven years following THR was also measured, using a computerised edge detection technique (PolyWare Rev 5, Draftware) of analysing standard radiographs.


Tamara Huff George F Chimento Sheena Babin Luci Brandner

Total joint arthroplasty is one of the most common procedures performed in orthopaedic surgery. Over 600,000 total hip and total knee replacements are performed in the United States each year. At our 550 bed tertiary care facility, 437 total knee arthroplasties were performed in 2010 and 426 in 2011. Tranexamic acid is an antifibrinolyic synthetic derivative of aminocaproic acid used to prevent hemorrhage in patients undergoing surgical procedures. Several studies show decreased blood loss in patients receiving both intravenous and topical tranexamic acid.

Beginning in 2011, our surgeons began using topical tranexamic acid in an irrigation solution of 3 grams in 100 mL of normal saline after implant placement and prior to closure of the incision. Our study is a retrospective review comparing patients receiving total knee arthroplasties before and after the institution of tranexamic acid. The purpose of our study was to assess estimated perioperative blood loss, determining the cost effectiveness of using tranexamic acid while comparing adverse effects of using topical tranexamic acid in total knee arthroplasty. Our study includes 683 primary total knees, 373 that received did not receive topical tranexamic acid and 310 that did, from January 1, 2010 to October 31, 2011. There were no demographic differences between the 2 groups. Topical tranexamic acid significantly (p<0.0001) decreased blood loss in patients receiving primary total knee arthroplasties. There were no differences between groups in thromboembolic events or joint infections. Tranexamic acid significantly (p<0.0001) decreased both blood bank cost and total cost of stay resulting in nearly $1,500 savings per patient to our institution.


Riichiro Ichikawa Atsushi Funayama Atsuhiro Fujie Shunichi Kawasakiya

Introduction

Acetabular dysplasia is a common cause of osteoarthritis of the hip. Chiari pelvic osteotomy enables medialization of the center of the femoral head and improvement of coverage over the femoral head for hip dysplasia and prevents or delays progression of degenerative arthritis. We reviewed 104 patients after this augmentation procedure.

Patients and methods

Between 1989 and 2000, 167 patients with developmental dysplasia of the hip had undergone the surgery at university hospital. Among them, 104 patients were able to be traced after surgery for more than 10 years. The mean follow-up period was 15.5 years. There were 96 women and 8 men with an average age of 34.3 years at surgery. The average angle of osteotomy was 6.6 degree craniad to the horizontal plane. Ratio of migration of the distal pelvis was 42%.


Sadafumi Ichinohe Goro Tajima Yoichi Kamei Moritaka Maruyama Tadashi Shimamura

It is very difficult to perform total knee arthroplasty (TKA) for severe varus bowing deformity of femur. We performed simultaneous combined femoral supra-condyle valgus osteotomy and TKA for the case had bilateral varus knees with bowing deformity of femurs.

Case presentation

A 62-year-old woman consulted our clinic with bilateral knee pain and walking distability. She was diagnosed rickets and had bilateral severe varus bowing deformity of femurs from an infant. Her height was 133 cm and body weight was 51 kg. Bilateral femur demonstrated severe bowing and her knee joint demonstrated varus deformity with medial joint line tenderness, no local heat, and no joint effusion. Bilateral knee ROM was 90 degrees with motion crepitus. Bilateral lower leg demonstrated mild internal rotation deformity. Bilateral JOA knee score was 40 Roentgenogram demonstrated knee osteoarthritis with incomplete development of femoral condyle. Mechanical FTA angles were 206 degree on the right and 201 on the left. She was received right simultaneous femoral supra-condyle valgus osteotomy with TKA was performed at age 63. Key points of surgical techniques were to use the intramedullary guide for valgus osteotomy as temporary reduction and fixation then performed mono-cortical locking plate fixation. Several mono cortical screws were exchanged to bi-cortical screws after implantation of the femoral component with long stem. Cast fixation performed during two weeks and full weight bearing permitted at 7 weeks after surgery. Her JOA score was slightly improved 50 due to other knee problems at 9 months after surgery, her right mechanical FTA was decreased to 173, and she received left simultaneous femoral supra-condyle valgus osteotomy with TKA as the same technique at April of this year. She has been receiving rehabilitation at now.

Conclusions

Most causes of varus knee deformity are defect or deformity of medial tibial condyle and TKA for theses cases are not difficult to use tibial augment devices. However the cases like our presentation need supra-femoral condyle osteotomy before TKA. It was easy and useful to use intramedullary guide for valgus osteotomy as temporary reduction and fixation then performed mono-cortical locking plate fixation before TKA.


Hirotaka Iguchi Nobuyuki Watanabe Satona Murakami Kaneaki Tawada Hiroto Mitsui Masaaki Kobayashi Yuko Nagaya Hideyuki Goto Masahiro Nozaki Takanobu Ootsuka

Introduction

Navigation system has been used for very accurate surgery. It can also be useful for preoperative planning. A surgeon can understand whole surgery, plan the surgery and perform the surgery three dimensionally and accurately. But the planning procedures should be installed before everything is started. When the surgery will be done in an ordinary method, the surgeon would not find particular difficulties. But in sometimes the surgeon can have unordinary situation such as massive defect that should be treated with acetabular enforcement device and bone grafted. Using postoperative DICOM data which is predicted by preoperative planning using 3D CAD software, we will be able to use the navigation system for those cases with difficulties that is not supported.

Objectives

To establish a method to use a navigation system using preoperative planning data that is processed by our 3D CAD software which is not supported by the navigation system itself, including device preparation using plastic models.


Masayoshi Ikeda Yuka Kobayashi Ikuo Saito Takayuki Ishii Ayuko Shimizu Yoshinori Oka

We report the case of a 12-year-old boy with flexion loss in the left elbow caused by deficient of the concavity corresponding to the coronoid fossa in the distal humerus. The range of motion (ROM) was 15°/100°, and pain was induced by passive terminal flexion. Plain radiographs revealed complete epiphyseal closure, and computed tomography (CT) revealed a flat anterior surface of the distal humerus; the coronoid fossa was absent. Then, the bony morphometric contour was surgically recreated using a navigation system and a three-dimensional elbow joint model. A three-dimensional model of the elbow joint was made preoperatively and the model comprising the distal humerus was milled so that elbow flexion flexion of more than 140° could be achieved against the proximal ulna and radius. Navigation-assisted surgery (contouring arthroplasty) was performed using CT data from this milled three-dimensional model. Subsequently, an intraoperative passive elbow flexion of 135° was obtained. However, active elbow flexion was still inadequate one year after operation, and a triceps lengthening procedure was performed. At the final follow-up one year after triceps lengthening, a considerable improvement in flexion was observed with a ROM of −12°/125°. Plain radiographs revealed no signs of degenerative change, and CT revealed the formation of the radial and coronoid fossae on the anterior surface of the distal humerus. Navigation-assisted surgery for deformity of the distal humerus based on a contoured three-dimensional model is extremely effective as it facilitates evaluation of the bony morphometry of the distal humerus. It is particularly useful as an indicator for milling the actual bone when a model of the mirror image of the unaffected side cannot be applied to the affected side as observed in our case.


Masami Ishimaru Kazunori Hino Hiromasa Miura

Introduction

Accurate alignment and sizing of the femoral component in total knee arthroplasty (TKA) is important for stability and functional outcomes. In relation to the shape of the distal femur, it has been reported that the medial-lateral (ML) femur width in women is narrower than that in men for the same antero-posterior (AP) length. In addition, it has been noted that the elevation of the anterior condyle in women is lower than that in men. Therefore, in TKA for women, it is suggested that a medial or lateral overhanging femoral component can cause pain or limit the range of motion (ROM). As a result, a gender-specific implant for women has been developed. However, there are few studies addressing the morphological dimensions of the distal shape of the femur in the Japanese population. The objective of this study was to reveal the appropriateness of using gender-specific implant for Japanese women.

Methods

This study was based on 40 women (40 knees) and 40 men (40 knees) who had primary preoperative osteoarthritis of the knee. The average height was 161.2 cm for men and 149.4 cm for women. The average weight was 68.0 kg for men and 58.5 kg for women. These are significantly different. Resection of the distal femur for TKA was simulated with preoperative computed tomography (CT) data. The ML width on the anterior and distal cut surface, the ML width at the surgical epicondylar axis (SEA) level, the maximum AP length at the medial and lateral condyle, and the AP length after resection were measured. These values were compared between men and women, and compatibility with NexGen LPS-Flex and Gender Solution Femur (GSF) (Zimmer, Warsow, Ind) was evaluated.


Hisashi Iwade Toru Kawasaki Kunihiko Tajima Yasuhiro Sakurai Keita Uetsuki Alex Turner Naohide Tomita

Background

dl-α-Tocopherol (vitamin E) blended ultra-high molecular weight Polyethylene (UHMWPE) was originally developed as a bearing material for use in knee prostheses (1). The reduced biological response observed for vitamin E (VE) blended UHMWPE wear particles in in vitro experimentation (2) has also demonstrated the materials potential for use in other orthopedic applications, especially total hip arthroplasty (THR). However, due to the excellent results achieved by highly crosslinked UHMWPE in hip simulator testing (3), the use of VE blended UHMWPE in THR would similarly require crosslinking. It was previously reported that VE radicals are formed during radiation crosslinking of VE blended UHMWPE (4), and it is hypothesized that these VE radicals may negatively impact the materials biological activity. In this study, ascorbic acid 6-palmitate (lipophilic vitamin C) was applied to electron-beam-irradiated VE blended UHMWPE in an attempt to oxidatively reduce the VE radicals. Electron Spin Resonance (ESR) was used to measure the number of VE radicals within the material and evaluate the regenerating effect of ascorbic acid 6-palmitate.

Materials & Methods

UHMWPE resin powder (GUR 1050, Ticona, USA) was mixed with dl-a-Tocopherol (vitamin E) at 0.3 wt% and molded under direct compression at 25 MPa and 220°C. Virgin samples were produced by the same process, but without the addition of vitamin E (VE). Cylindrical pins (length: 40 mm, diameter: 3.5 mm) were then machined from these samples, packaged in a vacuum, and irradiated by electron-beam at 300 kGy. Samples were subsequently doped with either ascorbic acid 6-palmitate (Sigma, Japan) or ethanol (Ethanol 99.5%, Kishida, Japan) and subjected to a hydrostatic pressure of 100 MPa for 7, 14, and 21 days at room temperature. Radical measurements were made using ESR at 9.44 GHz and room temperature. All ESR spectra were recorded at 0.1 mW microwave power and 0.1 mT modulation amplitude.


Hiroyoshi Iwaki Yukihide Minoda Mitsuhiko Ikebuchi Yoichi Ohta Maki Itokazu Hiroaki Nakamura

INTRODUCTION

Cup orientation of total hip arthroplasty (THA) is critical for dislocation, range of motion, polyethylene wear, pelvic osteolysis, and component migration. But, substantial error under manual technique has been reported specially in revision THA due to a bone loss and poor anatomical landmark. We have used three kinds of navigation systems for cup positioning in primary and revision THA.

OBJECTIVES

The purpose of this study is to evaluate the accuracy of navigation in revision THAs.


Keiji Iwamoto Tetsuya Tomita Takaharu Yamazaki Norimasa Shimizu Masahiro Kurita Kazuma Futai Yasuo Kunugiza Hideki Yoshikawa Kazuomi Sugamoto

Background

Various postoperative evaluations using fluoroscopy have reported in vivo knee flexion kinematics under weight bearing conditions. This method has been used to investigate which design features are more important for restoring normal knee function. The objective of this study is to evaluate the kinematics of a Low Contact Stress total knee arthroplasty (LCS TKA) in weight bearing deep knee flexion using 2D/3D registration technique.

Patients and methods

We investigated the in vivo knee kinematics of 6 knees (4 patients) implanted with the LCS meniscal bearing TKA (LCS Mobile-Bearing Knee System, Depuy, Warsaw, IN). Mean period between operation and surveillance was 170.7±14.2 months. Under fluoroscopic surveillance, each patient did a deep knee flexion under weight-bearing condition. Femorotibial motion was analyzed using 2D/3D registration technique, which uses computer-assisted design (CAD) models to reproduce the spatial position of the femoral, tibial components from single-view fluoroscopic images. We evaluated the knee flexion angle, femoral axial rotation, and antero-posterior translation of contact positions.


Toshiki Iwase Atsushi Kouyama Naoya Matsushita

Introduction

Segmental defects of the femur present a major problem during revision hip arthroplasty. In particular, calcar segmental defects may compromise initial and long-tem femoral stem stability.

Objective

The objective of the present study is to assess mid-term clinical and radiographic follow-up results at least two years after femoral revision comprising reconstruction for calcar segmental defect using metal wire mesh and impacted morcellised allograft.


Full Access
Reza Jenabzadeh Selin Munir Jenny Burke William K Walter Bernard Zicat William L Walter

Introduction

The Delta Motion device (developed by Finsbury Orthopaedics, Leatherhead, United Kingdom, now manufactured by DePuy, Leeds, United Kingdom) is a pre-assembled factory fitted cup. It has been introduced to overcome some of the concerns relating to intra-operative assembly with improper seating of the liner and chipping. This device has a thinner shell and liner in comparison with other cups, allowing the use of larger sized heads which should help reduce the risk of impingement and dislocation. A drawback of the pre-assembled design is the inability to use supplementary screws to achieve stability and the difficulty in obtaining primary stability compared with a thin titanium shell. To date we are not aware of any publications reviewing the outcomes of these devices.

Methods

206 DeltaMotion cups were implanted in 195 patients, between Dec 2008 to Dec 2009 by the three senior authors. All the hips had the same stem (Osteonics) and a ceramic head was used. Data was prospectively collected and we reflect on our two year results.


Dennis Molloy Reza Jenabzadeh William Walter Tim Hasted

Sagittal stability of the knee is believed to be of significant importance following a total knee arthroplasty. We examine three different knee designs at a minimum of twenty-four months postoperatively. Sagittal stability was measured at four degrees of flexion; 0°, 30°, 60° and 90° to examine the effect of design on mid-flexion stability.

The knee designs included the rotating platform LCS design, the cruciate sparing Triathlon system and the medial rotating knee design, MRK.

Following ethical approval 50 cases were enrolled into the study, 15 male and 35 female. Eighteen LCS, 18 MRK and 14 Triathlon knee designs were analysed. Sagittal stability was measured using the KT1000 device. Active range of movement was measured using a hand held goniometer and recorded as was Oxford knee score, WOMAC knee score, SF12 and Kujala patellofemoral knee score.

Mean follow-up was 37 months postoperative with a mean age of 73 years. Mean weight was 82.7 kgs and height 164 cms. There was no significant difference in preoperative demographics between the groups. Mean active post-operative range of motion of the knee was from 2–113° with no significant difference between groups.

Sagittal stability was similar in all three groups in full extension; however the MRK design showed improved stability in the mid-range of flexion (30–90°). Patient satisfaction also showed a similar trend with MRK achieving slightly better patient reported outcomes than that of the LCS and Triathlon systems, although this was not statistically significant.

All three knee designs demonstrated good post-operative range of movement with comparative improvement of patient scores to other reported studies. The MRK knee design showed an improved mid-flexion sagittal stability.


Jean-Yves Jenny Rolf Miehlke Dominique Saragaglia

INTRODUCTION

Polyethylene wear is one of the reasons for failure of total knee replacement (TKR). There are several reasons for wear, and the femoro-tibial contact area is an important factor. Mobile bearing, highly congruent prostheses might be more resistant to polyethylene wear than fixed bearing, incongruent prostheses. We evaluated the 5- to 8-year experience of three university departments by using an original system with following highlights: implantation with a navigation system, extended congruency up to 90° of flexion, floating polyethylene component with non-limited movements of rotation, antero-posterior translation and medio-lateral translation.

MATERIAL

347 patients have been operated on in the three participating departments with this new prosthesis system between 2001 and 2004, and have been prospectively followed with clinical and radiologic examination with a minimal follow-up time of 5 years. There were 246 women and 101 men, with a mean age of 67 years.


Johannes F Plate Gary Poehling Jason Lang Riyaz Jinnah

Introduction

Unicompartmental knee arthroplasty (UKA) has seen renewed interest in recent years and is a viable option for patients with limited degenerative disease of the knee as an alternative to total knee arthroplasty. However, the minimally invasive UKA procedure is challenging and accurate component alignment is vital to long-term survival. Robotic-assisted UKA allows for greater accuracy of component placement and dynamic intraoperative ligament balancing which may improve clinical patient outcomes. The purpose of this study was to examine the clinical outcomes in a large, consecutive cohort of patients that underwent robotic-assisted UKA.

Materials and Methods

A search of the institutional joint arthroplasty registry identified 507 patients with a mean age of 63 years (range, 28 to 88 years) who underwent robotic-assisted UKA between July 2008 and June 2010. Clinical outcomes were evaluated using the Oxford Knee Score and patients without recent follow-up were contacted by telephone. The revision rate and time to revision were also examined.


Yoshitomo Kajino Tamon Kabata Toru Maeda Shintaro Iwai Kazunari Kuroda Kenji Fujita Hiroki Kawashima Shigeru Sanada Hiroyuki Tsuchiya

Introduction

Hip resurfacing arthroplasty has been surgical options in younger and more active patients with osteoarthritis (OA) and osteonecrosis (ON) of the femoral head. Although excellent midterm results of this procedure have been reported, there is a concern about postoperative impingement between the preserved femoral neck and the acetabular component. There were few reports about kinematics after hip resurfacing. Therefore, the purpose of this study was to investigate the postoperative motion analysis after hip resurfacing using a noble dynamic flat-panel detector (FPD) system by which clear sequential images were obtained with low dose radiation exposure.

Materials and methods

11 patients (mean age: 47.8 ± 7.4), 15 hips were included in this study. There were ten men and one woman. The preoperative diagnoses were ON of the femoral head in 10 hips, OA in 3 hips, and others in 2 hips. Mean postoperative follow-up period was 25.1 ± 21.6 months. Femoral anteversion, cup inclination and cup anteversion were measured on computed tomography and plain radiograph. Impingement signs such as the reactive osteophyte formation and divot around the femoral neck were also investigated on the anteroposterior (AP) and lateral radiographs. Sequential images of active and passive flexion motion in 45-degrees semilateral position, and active abduction motion in a supine position were obtained using a noble dynamic FPD system.


Hirnori Kaneko Yutaka Hoshino Yoshihiko Saito Daisuke Utajima Takashi Tsuji Yasunori Tsukimura Hitoshi Abe Kazuhiro Chiba

Introduction

Since2007, we have used CT-based fluoroscopy-matching navigation system (Vector Vision Hip Ver.3.5.2, BrainLAB, Germany) in Total hip arthroplasty. This system completes the registration procedure semi-automatically by matching the contours of fluoroscopic images and touching 3 adequate points to the contours of 3D bone model created in the computer. Registration procedure using fluoroscopic figures has finished before making surgical incision. It needs no elongation time during the operation. The accuracy of navigation system depends on the techniques of registration used for the navigation and secure fixation of the dynamic reference markers. These could be affected by the different type of approaches. The objective of this study was to evaluate the accuracy of CT-based fluoroscopy-matching navigation system in THA and compare the cup position by anterolateral and posteolateral approaches.

Material and method

We analysed the acetabular cup in consecutive 132 hips with both intra-operative and post-operative alignment data (based on navigation system and CT evaluation), including 65 cases with anterolateral approach(Modified Watson Jones) (Group AL) and 67 cases with posterolateral approach(Group PL). We aimed the cup angle for THA as following, the inclination: 40 degrees, the anteversion: 20 degrees. Anteversion on the navigation system must be adjusted by the pelvic tilt.


Ryutaku Kaneyama Hideaki Shiratsuchi Kazuhiro Oinuma Yoko Miura Tatsuya Tamaki

Introduction

In TKA, it is important to make the equal extension and flexion gap (EG and FG) of the knee. Although, this principal concept applies to all knees, flexion contracture is known to have difficulties to achieve the equal EG and FG because of its smaller EG than usual. Whereas, it is also well known that PCL resection makes FG wider than EG, however, many surgeons recommend PCL resection in case of flection contracture because it is easy to manage during surgery, nevertheless the risk of further gap unbalance. Although, flexion contracture is not rare in TKA, the controversial problem of the PCL resection for the flexion contracture still remains even in today.

Materials and methods

To investigate this contradiction, we measured intra-operative EG and FG of the knee with 20 degree or more pre-operative flexion contracture. The gaps were measured by 3 different ways; a tension device system with 30 and 40 pound tension (group 1 and 2) and a spacer block system which had 1 mm increment thickness variation (group 3). The cases were 41, 46 and 51 knees in group 1, 2 and 3 respectively. Group 1 and 2 have overlapping in 27 knees.


Hyuk-Soo Han Seung-Baik Kang

The long-term outcome and survivorship of TKA in Asian countries have been reported to be excellent, comparable to Western countries. However, increased knee flexion is required for many daily activities in Asian cultures, which remains a major problem to be resolved. High-flexion TKA designs have been introduced to improve flexion after TKA and to allow a high degree of flexion in a safe manner. However, several biomechanical studies have shown that high-flexion designs have a greater risk for the loosening of the femoral component compared to the conventional TKA designs. We evaluated the implant survival and the mid-term clinical and radiological outcomes of Asian patients who had undergone high-flexion TKA and assessed whether high-flexion activities increased the risk of premature failure.

We prospectively followed 72 Nexgen LPS-flex fixed TKA in 47 patients implanted by a single surgeon between March 2003 and September 2004. Five patients (6 knees) expired during follow-up. A Kaplan-Meier survivorship analysis using revision surgery as the end point was used to determine the probability of survival for the cohort and the equality of survival between two subgroups who could perform high-flexion activities or not. Median follow-up was 6.5 (0.9–8.6) years.

Twenty-five patients (33 knees) received a revision for aseptic loosening of the femoral component at a mean of 3.5 years (range, 0.9–7.8 years). According to the Kaplan-Meier survivorship analysis, the probabilities of survival without revision for aseptic loosening are 66.7% and 51.8% at 5 and 8 years, respectively. The 8-year cumulative survivorship is lower (30.6%) when squatting, kneeling, or sitting cross-legged could be achieved than if none of these activities were possible (78.3%). In the surviving knees, non-progressive radiolucent lines were observed around the femoral component of 12 patients (15 knees) and one tibial component.

The overall mid-term high-flex implant survival of our Asian cohort is lower than that of the conventional and other high-flexion designs. This unacceptable high rate of femoral component loosening is strongly associated with postoperative high flexion activities.


Masashi Kawasaki

Purpose

The purpose of this study is to inspect balance of the pelvis in the acetabular operation of total hip arthroplasty (THA) using direct anterior approach (DAA), and it is to examine precision of the acetabular socket setting.

Materials and Methods

We performed THA using DAA to 104 patients (114 hips) joints from August 2006 to April 2009 and identified for seventy five patients (eighty four hips) that imaging of the postoperative CT was possible. The orientation of acetabular sockets were performed using an alignment guide which assumed an operating table an axis from August 2006 to September 2008 (A group), and using an alignment guide which assumed a pelvis an axis from October 2008 to May 2009(B group). A group were thirty eight patients (forty four hips), and B group were twenty eight (thirty). There were two men and thirty six women in A group, and one man and twenty seven women in B group. The average age of both groups was 66 years old. The objective angle of the acetabular socket was performed as angle guide of abduction of 45° and anteversion of 20°. The orientation of the acetabular socket converted the angle of postoperative CT into radiographic angle, and measured it. For sixteen hips in B group, both angle guide was used, and there were measured a difference of two angle guide in the acetabular operation as movement of the pelvis. The examination item assumed it the mean values of angle for the acetabular socket in both groups, precision to set up the acetabular socket to planned orientation within ±5 °and a mean difference of two angle guides of sixteen hips in B group.


Seyyed Morteza Kazemi Faramarz Mosaffa Alireza Eajazi Mohammad Kaffashi

Total hip arthroplasty (THA) is associated with high intraoperative and postoperative blood loss. Antifibrinolytic drugs have been used to minimize the potential risks of bleeding and blood transfusion. Studies on the effect of tranexamic acid on decreasing blood loss in THA have revealed interesting results, but most have focused on cemented THA. Yet its benefits in THA, especially in cementless THA, have not been proved. We conducted a prospective double-blind randomized controlled study on 64 patients who were candidates for cementless THA under epidural anesthesia between 2006 and 2008. Patients were randomly assigned into study and control groups. Patients in both groups were well matched regarding preoperative characteristics. Five minutes preoperatively 32 patients of the study and control groups received 15 mg/kg tranexamic acid or normal saline intravenously respectively. Our findings showed a significantly smaller decrease in 6- and 24-hour postoperative hemoglobin levels, less intraoperative and postoperative bleeding, and less need for allogenic blood transfusion in the tranexamic acid group. Our results also revealed a higher mean of 6- and 24-hour hematocrit level and shorter hospital stay in the tranexamic acid group compared to the control group, which were not statistically meaningful. In our study no thromboembolic event was seen; except 1 patient in the control group. Our study showed that administering tranexamic acid before the start of cementless THA under epidural anesthesia can reduce intraoperative and postoperative bleeding as well as need for blood transfusion.


Prue Keith

Rural surgical practice in Australia provides a unique environment to the Orthopaedic Surgeon. Whilst most of the work load mimics that of city practice, the rural surgeon has little choice but to master a broad schema of surgical skills, and keeping up with the current literature and techniques can be challenging.

At our public hospital over the last audited twelve month period, 108 primary total knee replacements were performed by 4 surgeons out of 236 joint replacements including revision surgeries. At the Private hospital a total of 215 joint replacements were performed in the same period including revision surgeries, of which 127 were knee arthroplasties.

It is recognised that the incidence of complications from arthroplasty can be increased in low volume joint replacement surgeons.

This centre is a mid volume centre, but rural and generally underfunded.

In light of this, it is not unreasonable to look at techniques or evolving technologies that may improve the ability of an individual surgeon to position a joint replacement in an optimal position and with economic consideration.

Conventional navigation has a number of factors associated with it that may make its use in a rural centre less attractive. These include capital cost of both hardware and software; Most rural centres do not have the ability to purchase the hardware and thus the issue of transporting hard ware on site, and representative support, may all be issues.

The potential benefit of patient specific implants [PSI] may thus be two-fold in this setting. The surgeon and the patient benefit from the technology, but the technology does not need to be transported to the site.

As a result of these considerations, a single surgeon in a rural centre, commenced using PSI's after gaining initial experience with the implant using traditional techniques.

This early study looks at this experience and attempts to quantify some of the issues around this technology.


Elie Khoury Jenny Burke Mark Gillies

Introduction

Metal on metal (MoM) bearings have been dealt a severe blow in the past few years. The release of metal ions may have arisen from corrosion, wear, or a combination of the two. Edge loading due to implant malposition is thought to cause a failure of lubrication and to contribute to excessive wear and increased metal ion release [1]. Literature reports aseptic lymphocytic vasculitis-associated lesions (ALVAL) are associated with a variety of failures which occur to some degree in all implanted metal femoral components [2, 3]. Moreover, Willert et al [4] has described ALVAL in non-MoM bearing designs too. This paper has investigated the metal ion release due to total hip replacement (THR), Hip Resurfacing (HR) and total knee replacement (TKR).

Methods

Following human ethics approval 200 patients were enrolled in this single surgeon randomised controlled study. The treatment groups were total knee replacement (TKR) (n=100), HR (n=50) and THR (n=50). Serum cobalt (Co) and chromium (Cr) ion levels were taken preoperatively for baseline measurement then at 6 month, 1 year and 2 years postoperatively.


Yongbum Kim

Introduction

47 yrs male patient had a prior history

2005 Fx. proximal tibia (open Fx.)

2007 Metal removal

2008 Arthroscopic debridement (2 times)

He visited out hospital with severe pain and tenderness X-ray (Fig 1) and MRI (Fig 2) findings as follows.

Conclusively, He had a chorinic osteomylitis of proximal tibia with soft tissue absess.

1st Surgery

I did arthroscopic debridement Arthroscopic finding shows synovitis, meniscus tear and chondromalacia. I did meticulous debridement (irrigation & curettage)

2nd Surgery

He did primary total knee arthro-plasty instead of two-stage exchange arthroplasty in may, 2010 at the another hospital

3rd Surgery

After 7 months since he had did total knee arthroplasty, he visited to my hospital again with sudden onset of painful swelling & heating sensation

4th Surgery

I did second stage reimplantation for infected total Knee arthroplasty after 7 weeks. Now he got a pain relief & ROM restroration.

Results

Follow up 12 months X-ray showing all implants to be well-positioned and stable. Clinically, there was no implant considered to be loose

In this study, the knee society and functional scores at final follow up were 82 and 68.


Hee Joong Kim

Purpose

Complete wear-out of Polyethylene (PE) liner results in severe metallosis following articulation of the artificial head with the acetabular metal shell. We postulated that an adverse response can be led to surrounding bone tissue and new implant after revision surgery because the amount of PE wear particle is substantial and the metal particles are infiltrated in this catastrophic condition. We evaluated clinical characteristics and the survival rate of revision total hip arthroplasty (THA) performed in patients with severe metallosis following failure of PE liner.

Materials and Methods

Between January 1996 and August 2004, severe metallosis following complete wear-out of PE liner were identified during revision THA in 28 hips of 28 patients. One patient had died at 7 days after surgery and 3 patients could not be reached at 5 year follow-up. Twenty-four hips of 24 patients (average age, 47.5 years) were followed for at least 6.5 years (average, 11.3 years; range, 6.5–15.9 years) and were evaluated. The mean time interval between prior surgery and the index revision surgery was 9.6 years (range, 4.0–14.3 years). The indications for revision surgery were osteolysis around well-fixed cup and stem in 22 hips and osteolysis with aseptic loosening of the cup in 2 hips. Bubble sign was observed on preoperative radiograph in 10 hips. Total revision, cup revision, and solitary bearing change were performed in 13, 10, and one hip respectively. A cementless implant was used in 23 hips and acetabular reinforcement ring was used in one. Clinical evaluation was performed using Harris hip scores and Kaplan-Meier survival analysis was performed. Multivariate analysis was performed with age, gender, BMI, bone defect type, existence of bubble sign and type of revision surgery as variables to evaluate the association with osteolysis or loosening.


Dai Kiyotomo Kazuomi Sugamoto Tsuyoshi Murase Tetsuya Tomita Yasuo Kunugiza Kunihiko Kawashima Kazuma Futai Koichi Kuramoto Keitaro Yamamoto

Introduction

Regarding TKA, patient specific cutting guides (PSCG), which have the same fitting surface with patient's bones or cartilages and uniquely specify the resection plane by fitting guides with bones, have been developed to assist easy, low cost and accurate surgery. They have already been used clinically in Europe and the USA. However little has been reported on clinical positioning accuracy of PSCG. Generally, the methods of making PSCG can be divided into 3 methods; construct 3D bone models with Magnetic Resonance (MR) images, construct 3D bone models with Computed Tomography (CT) images, and the last is to construct 3D bone models with both MR and CT images. In the present study, PSCG were made based on 3D bone models with CT images, examined the positioning accuracy with fresh-frozen cadavers.

Materials and Methods

Two fresh-frozen cadavers with four knees were scanned by CT. Image processing software for 3D design (Mimics Ver. 14, Marialise Inc.) was used to construct 3D bone model by image thresholding. We designed femoral cutting guides and tibial cutting guides by CAD software (NX 5.0, Siemens PLM Software Co.). CT free navigation system (VectorVision Knee, BrainLab, Inc.) was used to measure positioning error. Average absolute value of positioning error for each PSCG was derived.


Fady Youssef Sabry Alison Klika Leonard Buller Sarim Ahmed Caleb Szubski Wael Barsoum

Background

Two-stage revision is considered the gold standard for treatment of knee prosthetic joint infections. Current guidelines for selecting the most appropriate procedure to eradicate knee prosthetic joint infections are based upon the duration of symptoms, the condition of the implant and soft tissue evaluated during surgery and the infecting organism. A more robust tool to identify candidates for two-stage revision and who are at high risk for treatment failure might improve preoperative risk assessment and increase a surgeon's index of suspicion, resulting in closer monitoring, optimization of risk factors for failure and more aggressive management of those patients who are predicted to fail.

Methods

Charts from 3,809 revision total joint arthroplasties were reviewed. Demographic data, clinical data and disease follow-up on 314 patients with infected total knee arthroplasty treated with two-stage revision were collected. Univariate analyses were performed to determine which variables were independently associated with failure of the procedure to eradicate the prosthetic joint infections. Cox regression was used to construct a model predicting the probability of treatment failure and the results were used to generate a nomogram which was internally validated using bootstrapping.


Lawrence Kohan Clarice Field Dennis Kerr

Comparisons of blood metal ion levels of cobalt and chromium (CoCr) between metal-on-metal total and resurfacing hip arthroplasties are limited. High levels of CoCr may result in long-term adverse biological effects. We compare metal ions levels between total and resurfacing implants.

70 patients (28 males and 42 females) had a total hip arthroplasty using the Birmingham (Smith & Nephew) modular femoral component and a variety of stems, articulating with the Birmingham resurfacing component. The average age was 65.5 (±6.8) years and an average follow-up of 6.0 (±2.2) years. 170 patients (145 male and 25 female had a Birmingham resurfacing arthroplasty with an average age of 54.7 (±9.9) years and an average follow-up of 5.9 (±3.0) years. CoCr levels were measured. Bivariate correlations and independent samples t-tests were applied to determine similarities and differences within and between groups.

Average ion levels in total arthroplasty patients were: Co 114.17 (±94.01) nmol/L (range 2–414); and Cr 75.12 (±68.45) nmol/L (range 10–312). Average levels in hip resurfacing arthroplasty were: Co 55.98 (±79.5) nmol/L (range 7–505); and Cr 70.77 (±87.41) nmol/L (range 5–751). Both total and resurfacing groups showed significant correlations (p<0.01) between Co and Cr levels. A significant difference was observed between the total and resurfacing group Co levels (p<0.0001). No significant difference was shown between group Cr levels (p>0.672).

The average total hip replacement CoCr levels were higher than the hip resurfacing levels. While the overall activity level may be higher in the resurfacing group, possibly the incidence of stop/start frequency may be higher in the total hip replacement group.

Hip resurfacing arthroplasty average CoCr levels are lower than those of total hip replacement patients. Associations between Co and Cr metal ion levels are shown within each group. Co levels differ significantly between groups where Cr does not. Long-term follow-up of CoCr levels are required.


Lawrence Kohan Clarice Field Dennis Kerr

The Birmingham mid-head hip resurfacing arthroplasty (Smith & Nephew, Tennessee) (BMHR) is designed for use in patients with avascular necrosis of the femoral head. The BMHR has limited short-mid term follow-up results. We report the experience of 27 consecutive BMHR procedures with a minimum two year follow-up.

23 patients (20 males and 3 females) with an average operation age of 49.8 years (SD ±10.9) (22–65) were investigated. The mean follow-up period was 3.0 years (SD ±0.77). The operations were between April 2008 and November 2011 by one surgeon. Data and outcome measurements were collected prospectively and analysed retrospectively. Procedures were reviewed to determine function. We evaluated Harris Hip Scores, Short Form-36 (SF-36v2) Scores, Tegner Activity Score Scores and McMaster Universities Osteoarthritis Index Scores (WOMAC) comparatively at preoperative, six month and yearly intervals. Paired samples t-tests were applied to determine improvements where p<0.05 was deemed as significant.

There were no patient deaths. There were no revisions. Harris Hip scores for pre-operative 6, 12, 24 and 36 month intervals were: 52.30, 84.14, 83.07, 87.50 and 89.50. Average pre-operative 6, 12, 24 and 36 month SF36v2 Total scores were: 116.54, 124.32, 130.44, 135.97 and 133.18. Tegner scores for pre-operative 2.75, 3.29, 3.00, 3.67 and 3.01. WOMAC Total scores for aforementioned intervals for the posterior approach were: 59.51, 84.22, 90.30, 86.86 and 92.25.

The mean Harris Hip scores improved significantly between preoperative and 6, 12, 24 and 36 months (p<0.001). The mean SF-36v2 physical scores improved significantly between preoperative and 6, 12, 24 and 36 months (p<0.016). WOMAC scores improved significantly between preoperative and 6, 12, 24 and 36 months (p<0.017).

The presence of avascular necrosis significantly increases the revision rate for hip resurfacing surgery. The BMHR prosthesis, in this short term follow-up, appears to avoid the main cause of failure, femoral component loosening. Longer term efficacy remains to be seen. We plan to continue close supervision of these patients.


Lawrence Kohan Clarice Field Dennis Kerr

The Birmingham Hip Resurfacing (BHR) has been used in the younger more active patient for the treatment of advanced osteoarthritis. Long-term follow-up of the BHR is limited. The Australian national joint replacement registry shows that failure rates vary greatly, depending on implant types. 77 consecutive BHR procedures with a minimum ten year follow-up are reported.

There were 70 patients (44 males and 26 females) with an average operation age of 57.4 years (SD ±12.6). All patients were evaluated, including the “learning curve” patients. The mean follow-up period was 11.42 years (SD ±0.50). The arthroplasties were performed between April 1999 and December 2000 by one surgeon, with a standardised patient selection set of criteria. Data and outcome measurements were collected prospectively and analysed retrospectively. We evaluated Harris Hip Scores, Short Form-36 (SF-36v2) Scores, Tegner Activity Score Scores and McMaster Universities Osteoarthritis Index Scores (WOMAC) comparatively at preoperative, six month and yearly intervals

In 8 patients (10 procedures) the implant was in situ at the time of death. Revision was carried out in 6 hips (7.8%) at a mean time period of 2.5 years (0–10) post-operatively. Failure was due to femoral neck fracture in four patients, acetabular loosening in one and avascular necrosis of the femoral head, leading to loosening, in one patient. Kaplan-Meier analysis showed survivorship of 92.2% to 10 years. The mean Harris Hip scores (paired t-test, p<0.05) improved significantly from 59.7 preoperatively to 80.1 at ten years. The mean SF-36v2 physical scores (paired t-test, p<0.05) improved significantly from 35.09 preoperatively to 47.83 at ten years. WOMAC scores (paired t-test, p<0.05) improved significantly from 54.61 preoperatively to 85.89 at ten years.

The BHR prosthesis, in this series, has been shown to be effective, reliable, and durable in this group of highly active, relatively young patients. Problems with metallic debris, sensitivity reactions, and osteolysis have not been seen. However, we believe that with better selection criteria, improved understanding of component positioning and surgical techniques, results can be improved.


Lawrence Kohan Clarice Field Dennis Kerr

There is a report that higher failure rate in uncemented total knee replacement components due to loosening. However, uncemented fixation has been an attractive concept because of bone preservation and revision surgery, potential improved load transfer, and decreased surgical time. “Regenerex” is a porous titanium layer with excellent initial fixation, and the promise of providing favourable biological fixation. This is used with the Biomet Vanguard total knee replacement.

14 patients had undergone total knee replacement surgery comprising 11 men and three women with an average age of 63.07 years, and a body mass index of 30.33. Three of these patients required revision, because of tibial component loosening within 12 months of surgery. There were two men and one woman with an average age of 63.33 and BMI of 34.55. Clinically, patients developed pain and a gradual deformity as a result of a symmetrical collapse of the proximal tibial bony support surface.

Histopathology on the removed specimens shows the development of fibre cartilaginous metaplasia with evidence of necrotic bone. This was similar in all patients. There was no foreign body giant cell reaction, and no evidence of infection. The appearance was suggested of osteonecrosis, occurring gradually.

The incidence of frequency of this complication with this component in our experience is of concern, and the aim of this presentation is to determine whether this is a more widespread phenomenon.


Michael Conditt Stefan Kreuzer Jennifer Jones Sam Dalal

Introduction

Traditional Total Knee Arthpolasty (TKA) replaces all 3 compartments of the knee for patients diagnosed with OA. There might be functional benefit to replacing only damaged compartments, and retaining the normal ligamentous structures. There is a long history of performing multi-compartment arthroplasty with discrete components. Laskin reported in 1976 that good pain relief and acceptable clinical results were achieved at two years in patients with bi-unicondylar knee replacement [Laskin 1976]. Other authors also have reported on bi-unicompartmental knee arthroplasty achieving successful clinical outcomes [Stockley 1990; Confalonieri 2005]. Banks et al. reported that kinematics of bi-unicompartmental arthroplasties during gait demonstrated some of the basic features of normal knee kinematics [Banks 2005]. These reports suggest that a modular approach to resurfacing the knee can be successful and achieve satisfactory clinical and functional results.

Objective

The primary objective of this study is to compare the functional outcomes of three patient groups treated for osteoarthritis.


Christian Kothny Jorg Jerosch Stefan Kreuzer

Aim

The purpose of the study was to analyse short- and medium-term results of a modern cementless short stem design hip joint endoprosthesis together with different parameters (offset, CCD, leg length), radiological findings and scores.

Material and Methods

186 cases using a metaphyseal fixed short stem prosthesis (MiniHip, Corin) at two hospitals were included for clinical follow-up. 180 patients were available for clinical follow-up with standardized scores: Oxford-Hip Score (OHS), Hip Dysfunction an Osteoarthritis Outcome Score (HOOS) and EQ-5D – Score. The scores were caught preoperatively and postoperatively every year.

Further on we could do a prospective radiological study of 250 consecutive hips with degenerative hip osteoarthritis were included (246 patients). These patients were operated by five different surgeons at 4 different hospitals. Standardized X-rays were performed with the same technique pre- and postoperatively in all patients. Different anatomical parameters of the hip were documented by using the pre- and postoperative x-rays (Offset, CCD angle, length of leg).

The 250 patients included 129 female and 117 male. The average age of the patients was 59.7 years (range: 27–82 years).

The whole follow-up and all measurements were performed by an independent examiner.


Sandeep Kumar

INTRODUCTION

There is historical evidence of increased incidence of transitional cell tumours of the renal tract in workers exposed to high levels of metal ions. This study was designed to establish any correlation between Metal on metal bearing hip arthroplasty and TCC.

METHODS

A prospective North-East database of 2900 Urology/Oncology cases was compared with the Freeman Joint Registry, which is a prospective database of all Arthroplasty performed since 2001 to establish any correlation with TCC. After comparing the Urology database with the Freeman Joint Registry from 2001 to 2011, a group of patients was identified who underwent hip replacement and had TCC of bladder. The incidence of TCC was calculated in patients who had metal on metal hip replacement and those who had metal on poly hip replacement. On comparing both the groups no significant difference in incidence of TCC of bladder was recorded.


Steven Kurtz Daniel MacDonald Jay Parvizi Gregg Roger Klein Gwo-Chin Lee Amanda Marshall Michael Mont Matthew Kraay Bernard Stulberg Arthur L Malkani Clare Rimnac

Introduction

The purpose of this multicenter study was to assess the oxidative stability, mechanical behavior, wear and reasons for revision of 2nd generation sequentially annealed HXLPE, X3, and compare it to 1st generation XLPE, Crossfire. We hypothesized that X3 would exhibit similar wear rates but lower oxidation than Crossfire.

Methods

182 hip liners were consecutively retrieved during revision surgeries at 7 surgical centers and continuously analyzed over the past 12 years in a prospective, multicenter study. 90 were highly crosslinked and annealed (Crossfire; Implanted 4.2±3.4 years, max: 11 years), and 92 were highly crosslinked and annealed in 3 sequential steps (X3; Implanted 1.2±1.5 years; max: 5 years). Oxidation was characterized in accordance with ASTM 2102 using transmission FTIR performed on thin sections (∼200μm) from the superior/inferior axis. Mechanical behavior was assessed via the small punch test (ASTM 2183).


Genymphas Higgs Steven Kurtz Josa Hanzlik Daniel MacDonald William M Kane Judd Day Gregg Roger Klein Jay Parvizi Michael Mont Matthew Kraay John Martell Jeremy Gilbert Clare Rimnac

Introduction

Wear debris generation in metal-on-metal (MOM) total hip arthroplasty (THA) has emerged as a compelling issue. In the UK, clinically significant fretting corrosion was reported at head-taper junctions of MOM hip prostheses from a single manufacturer (Langton 2011). This study characterizes the prevalence of fretting and corrosion at various modular interfaces in retrieved MOM THA systems used in the United States.

Methods and Materials

106 MOM bearing systems were collected between 2003 and 2012 in an NIH-supported, multi-institutional retrieval program. From this collection, 88 modular MOM THA devices were identified, yielding 76 heads and 31 stems (22 modular necks) of 7 different bearing designs (5 manufacturers) for analysis. 10 modular CoCr acetabular liners and 5 corresponding acetabular shells were also examined. Mean age at implantation was 58 years (range, 30–85 years) and implantation time averaged 2.2 ± 1.8 years (range, 0–11.0 years). The predominant revision reason was loosening (n=52). Explants were cleaned and scored at the head taper, stem taper, proximal and distal neck tapers (for modular necks), liner, and shell interfaces in accordance with the semi-quantitative method of Goldberg et al. (2002).


Anton Lambers Robert Jennings Andrew Bucknill

Introduction

Accurate prosthetic cup placement is very important in total hip arthroplasty (THA). When the surgeon is impacting the acetabular cup, it is assumed that the patient's pelvis is perpendicular to the operating table. In reality the pelvis may not be truly lateral, and error in patient positioning may influence the resultant cup orientation.

Objectives

The primary aim of this study was to examine the accuracy of patient positioning prior to THA. A secondary aim was to see if patient BMI influenced the accuracy of positioning.


Anton Lambers Robert Jennings Andrew Bucknill

Introduction

Leg length and offset are important considerations in total hip arthroplasty (THA). Navigation systems are capable of providing intra-operative measurements, which help guide the surgeon in leg length and offset adjustment.

Objective

This controlled study investigates whether the use of computer navigation leads to more accurate achievement of pre-operative leg length and offset targets in THA.


Anton Lambers Robert Jennings Andrew Bucknill

Introduction

Leg length and offset are important considerations in total hip arthroplasty (THA). Navigation systems are capable of providing intra-operative measurements of leg length and offset, and high accuracy has been shown in experimental studies.

Objective

This in-vivo study assesses the accuracy of an imageless navigation system, with a pin-less femoral array, in measuring offset and leg length changes.


Yoon Je Cho Joo-Hyun Lee Young Soo Chun Kee Hyung Rhyu Sangjoon Kwak Hyung-Min Ji Ye Yeon Won Myung-Chul Yoo

Purpose

To evaluate the radiological changes after metal on metal resurfacing arthroplasty.

Materials and Methods

Between December 1998 and August 2004, 166 hips in 150 patients who underwent metal resurfacing arthroplasty and followed up more than 4 years. Their mean age at the time of operation was 37.3 years(range, 15–68 years) and mean period of follow-up was 6.1 years(range, 48–95 months). The cause of arthroplasty included 115 avascular necrosis, 43 osteoarthritis, 7 ankylosing spondylitis, 1 haemophilic arthropathy. All patients had anteroposterior, translateral radiographs of the hip made preoperatively and each follow-up visit, and we analyzed radiographic findings such as radiolucencies or impingement signs around implant, neck narrowing and heterotopic ossification.


Xinning Li Zakary Knutson Daniel Choi Joseph Lipman Edward V. Craig Russell Warren Lawrence Gulotta

Introduction

While shoulder elevation can be reliably restored following reverse total shoulder arthroplasty (RTSA), patients may experience a loss of internal and external rotation. Several recent studies have investigated scapular notching and have made suggestions regarding glenosphere placement in order to minimize its occurrence. However, very few studies have looked at how changes in glenosphere placement in RTSA affect internal and external rotation. The purpose of this study was to determine the effect of glenosphere position on internal and external rotation range of motion at various degrees of scaption following RTSA. We hypothesized that alteration in glenosphere position will affect the amount of impingement-free internal and external rotation.

Methods

CT scans of the scapula and humerus were obtained from seven cadaver specimens and 3-Dimensional (3D) reconstructions were created. A corresponding 3D RTSA model was created by laser scanning the baseplate, glenosphere, humeral stem and bearing. The RTSA models were then virtually implanted into each specimen. The glenosphere position was determined in relation to the neutral position in 6 different settings: Medialization (5 mm), lateralization (10 mm), superior translation (6mm), inferior translation (6 mm), superior tilt (20°), and inferior tilt (15° and 30°). The humerus in each virtual model was allowed to freely rotate at a fixed scaption angle until encountering bone-bone or bone-implant impingement (180 degrees of limitation). Each model was tested at 0, 20, 40, and 60 degrees of scaption and the impingement-free internal and external rotation range of motion for each scaption angle was recorded.


David Liu

Fixed flexion contracture is often present in association with osteoarthritis of the knee and correction is one of the key surgical goals in total knee replacement. Surgical strategies to correct flexion contracture include removal of posterior osteophytes, posterior capsular release and additional distal femoral bone resection.

Traditional teaching indicates 2 mm of additional distal femoral bone resection will correct 10 degrees of flexion deformity. However some studies have questioned this figure and removing excessive distal femoral bone results in elevation of the joint line, potentially causing patella baja, alteration in collateral ligament tension through the flexion arc and mid-flexion instability.

The aim of our study is to determine the relationship between distal bone resection of the femur and passive knee extension in total knee arthroplasty.

A cohort of 50 patients, undergoing total knee arthroplasty, was recruited. Following complete femoral and tibial bone preparation, to simulate the effect of distal femoral bone resection, augments of 2 mm increments (2 mm, 4 mm, 6 mm, 8 mm) were placed onto the trial femoral component. The degree of flexion contracture with each augment was measured using computer navigation.

The results showed a 2 mm augment produced an average of 3.37 degrees of flexion deformity. A 4 mm augment led to an average of 6.68 degrees fixed flexion, whilst a 6 mm augment produced 11.38 degrees. To correct 10 degrees flexion deformity, an additional 6 mm distal femoral bone resection is required.

In conclusion, additional distal femoral bone resection may not be as an effective strategy as previously believed to correct fixed flexion deformity in total knee arthroplasty.


Bruce Love

Manufacturers and suppliers, described here as sponsors, who wish to have products approved and listed for use in Australian hospitals must follow a defined process.

They must obtain an Australian Registered Therapeutic Goods number (ARTG) for the product to be used.

For benefits to be paid for prostheses used under private health insurance arrangements a catalogue number is obtained after being approved through the Prosthesis Listing Advisory Committee (PLAC). Under PLAC each group of like prostheses is assessed by a Clinical Advisory group. (Hip Prosthesis Clinical Advisory Group, Knee Prosthesis Clinical Advisory Group).

Existing criteria are being enhanced as to the levels of evidence required for listing approval.

Essentially for joint replacements which are weight-bearing and in category three a two year clinical trial will almost always be necessary for any new prosthesis. Products must bw considered as non-inferior to comparator products.


Samuel MacDessi Darren Chen

Introduction

It is widely accepted that computer navigation more reliably restores neutral mechanical alignment than conventional instrumentation in total knee arthroplasty (TKA) surgery. Recently, magnetic resonance (MR) based instrumentation has been introduced to the market with a rapid growth in usage. However, a paucity of comparative data still exists on the precision of magnetic resonance (MR) based instruments in achieving acceptable lower limb alignment when compared to other validated techniques. In this analysis, we compare the radiographic outcomes of 3 techniques to achieve satisfactory prosthetic alignment by 2 surgeons using the same prosthesis and surgical technique.

Methods

A series of 180 patients who had undergone TKA surgery were included in this study. Two fellowship-trained knee surgeons performed all surgeries using the same cemented, posterior stabilized implants (NexGen, Zimmer, Warsaw, In). Patients were stratified in to 3 groups according to the technique used to align the knee; 1. Conventional Intra-medullary Instrumentation, 2. Computer Navigation (Orthosoft), and 3. MR-based guides (Zimmer PSI). All patients underwent a post-operative CT Perth Protocol to assess coronal, sagittal and rotational alignment of the femoral and tibial implants. A radiographer who was blinded to the alignment technique used performed all radiographic measurements. Outliers were defined at a deviation of more than 3 degrees from the mechanical axis in all planes of motion.


Samuel MacDessi Darren Chen Gregory Wernecke Bradley Seeto Sam Chia

Introduction

Total knee arthroplasty is a painful operation. Peri-articular local anesthetic injections reduce post-operative pain and assist recovery. It is inconclusive whether intra-operative injections of peri-articular corticosteroids are of benefit. Clinical Question: In patients with osteoarthritis who are undergoing TKA, does the addition of high or low dose corticosteroid to peri-articular injections of local anesthetic and adrenaline improve post-operative pain and range of motion?

Methods

A prospective, randomized, double-blinded study was undertaken to assess the efficacy of adding peri-articular corticosteroids to intra-operative, peri-articular high volume local anaesthetic in post-operative pain management following TKA. 127 patients were randomised into three groups receiving local anaesthetic alone (control) or either low dose (40 mg) or high dose (80 mg) peri-articular corticosteroid plus local anaesthetic. Primary outcomes included ROM and visual analog pain scores (VAS). Pain was defined as the worst pain lasting for more than 20 minutes, measured at both rest (RVAS) and during activity (AVAS).


Shinichi Maeno Seiji Saito Nobuyuki Fujita Toshiro Otani Takashi Matsumura Ko Masumoto Yousuke Takahashi Masahiro Ishizaka Masaki Akutsu Hidenari Sadakiyo

Total Knee Replacement (TKR) has been proven to be an effective procedure not only to eliminate pain but also to achieve better knee function. However, details improvements of balancing or walking ability have not been sufficiently elucidated yet.

Methods

25 consecutive knees of 21 patients, with medial osteoarthritis undergone TKR have been nominated in this study. All were done by a single surgeon, via mid vastus approach, using cemented PS implant with patellar resurfacing. Patients were arrowed to start full weight bearing from the next day.

Assessing walking ability, gait speed and width of a step were measured. As for balancing, “Functional Reach (FR)” which was the difference between arm's length and maximal forward reach (Duncan PW et al), “Timed Up and Go Test (TUG)” which was time while a patient rose from an arm chair, walked 3 meters, turned, walked back (Podsiadlo D et al), and sat down again, and possible period standing on one leg (one leg standing) were used. Every measurement was performed prior to the operation, and every 1-week after operation until 4-weeks postoperatively. Data were analyzed by one-way ANOVA, and then differences among means were analyzed using Bonferroni procedures. Also, the relation of improvements between ROM and each data were investigated by Pearson's correlation coefficient test.

Result

Every result showed the worst during the first week, followed by better results over time (p<0.05) (Fig. 1–3). The time point when better result than that of pre-operation could be achieved was 2 weeks in FR and one leg standing, 3 weeks in gait speed and width of a step, and 4 weeks in TUG, though statistically not significant. Each of the result was not correlated with its recovery rate of the ROM when compared at 4 weeks of time (r = 0.2–0.3). Interestingly, postoperative one leg standing period of contra-lateral leg showed improvement with similar tendency.


Pankaj Mahindra Mohammad Yamin Rajnish Garg Harpal Singh Selhi Deepak Jain Gurdarshan Singh

Objective

A study was performed in a tertiary health care centre to evaluate outcomes of arthroplasty in Indian Population. Various factors which may affect knee flexion after surgery were also evaluated.

Methods

82 patients with 60 unilateral & 22 bilateral total knee arthroplasties were included in the study. Assessment was done as per knee society knee score and function score. A simple functional questionaire including ability to squat, ability to sit cross leg, kneel while prayers, ability to use Indian toilet was filled and patients were rated accordingly as fair, good and excellent.


Ed Marel Len Walter

This study looks at Australian Orthopaedic Association National Joint Replacement Registry figures to try to see if any questions can be answered about the role of the trunion in some THR failures.

The Registry shows that large head (≥50 mm) hip resurfacings are doing well in appropriate patients, but the same size resurfacing cups with stemmed THR are doing poorly, while the smaller sizes in metal/metal stemmed THR continue to perform well.

The Registry also shows all stemmed THR with exchangeable (modular) necks have twice the revision rate of non exchangeable necks, and that these revisions are for dislocation as well as “loosening/lysis”.

One possible reason for the failure of large head metal – metal THRs is the trunion, which has been designed for use with small (22 mm–32 mm) femoral heads and is now being used with large (up to 56 mm) femoral heads.

We postulated that if the trunion were failing it might be seen more commonly with the smaller tapers such as the Stryker V40 taper, and that this might be seen with large (36 mm–44 mm) metal heads used on these tapers even in metal-poly hips.

Results from the Registry are shown.


Full Access
Ed Marel

Hip Resurfacing in its current metal on metal hybrid fixation form has been performed in large numbers in Australia since 1999.

Outcomes from the Australian Orthopaedic Association National Joint Replacement Registry are shown. While there is a wide range of outcomes these can be shown to depend on patient factors and implant factors.

Use of one of the successful implants (for example the Birmingham Hip) in a young male patient with osteoarthritis by a suitably trained surgeon can lead to good results.

In the AOA NJRR the 10 year cumulative percent revision rate for the Birmingham Hip in male patients under the age of 60 at the time of surgery is 3.3%


Tomoyuki Matsumoto Hirotsugu Muratsu Seiji Kubo Katsumasa Tei Hiroshi Sasaki Tokio Matsuzaki Takehiko Matsushita Masahiro Kurosaka Ryosuke Kuroda

Backgrounds

In order to permit soft tissue balancing under more physiological conditions during total knee arthroplasties (TKAs), we developed an offset type tensor to obtain soft tissue balancing throughout the range of motion with reduced patella-femoral (PF) and aligned tibiofemoral joints and reported the intra-operative soft tissue balance assessment in cruciate-retaining (CR) and posterior-stabilized (PS) TKA [1, 2]. However, the soft tissue balance in unicompartmental knee arthroplasty (UKA) is unclear. Therefore, we recently developed a new tensor for UKAs that is designed to assist with soft tissue balancing throughout the full range of motion. The first purpose of the present study is to assess joint gap kinematics in UKA. Secondly, we attempted to compare the pattern in UKA with those in CR and PS TKA with the reduced PF joint and femoral component placement, which more closely reproduces post-operative joint alignment.

Methods

Using this tensor, we assessed the intra-operative joint gap measurements of UKAs performed at 0, 10, 30, 45, 60, 90, 120 and 135° of flexion in 20 osteoarthritic patients. In addition, the kinematic pattern of UKA was compared with those of CR and PS TKA that were calculated as medial compartment gap from the previous series of this study.


Omid Alizadehkhaiyat Alexandros Kyriakos Mohamed Salah Singer Simon Frostick Ahmed Al Mandhari

Background

The Copeland shoulder resurfacing arthroplasty (CSRA) (Figure1) is a cementless, pegged humeral head surface replacement which has been in clinical use since 1986. The indications for CSRA are more or less the same as conventional stemmed arthroplasty. This procedure can be considered for all patients who require shoulder replacement due to GHJ arthritis resulted from primary or secondary OA, RA, and other variations of inflammatory arthritis. It is also suggested as the first choice option for relatively young patients with post-traumatic arthritis, avascular necrosis (AVN), and instability arthropathy. This observational study reports functional and radiological outcome in CSRA during 4 years follow-up.

Methods

109 consecutive patients with primary osteoarthritis (45.9%), rheumatoid arthritis (39.4%), rotator cuff arthropathy (9.2%), and avascular necrosis (5.5%) underwent CSRA. Patients including 68 females (63%) and 41 males (37%) underwent this procedure (63 right-sided and 46 left-sided including 9 bilateral shoulders). The outcome assessment included pain and satisfaction, Oxford Shoulder Score (OSS), Constant Score (CS), and SF-12. Imaging was reviewed for glenoid morphology (Walch classification) (Figure2) and humeral head migration. The average follow-up period was 4 years, (range: 1 to 10 years).


Shahram Amiri David Wilson Bassam Masri

INTRODUCTION

Rotational malalignment of the components in total knee arthroplasty has been linked to patellar maltracking, improper soft tissue balance, abnormal kinematics, premature wear of the polyethylene inlay, and subsequent clinical complications such as anterior knee pain (Barrack et al., 2001; Zihlmann et al., 2005; Lakstein at al., 2010). This study investigates an innovative image-based device that is designed to be used along with an intraoperative Isocentric (ISO-C) 3D imaging C-arm, and the conventional surgical instruments for positioning the femoral component at accurate rotational alignment angles.

METHODS

The new device was tested on 5 replica models of the femur (Sawbones). Zimmer NexGen total knee replacement instruments were used to prepare the bones. After making the distal transverse cut on the femurs, the trans-epicondylar-axis (TEA) were defined by a line connecting the medial and lateral epicondyles which were marked by holes on the bone models. The 4-in-1 cutting jig was placed and pinned to the bones with respect to the TEA considering 5 different planned rotational alignments: −10°, −5°, 0°, +5°, and +10° (minus sign indicating external and plus sign internal rotation). At this point, the jig was replaced by the alignment device using the head-less pins as the reference, and subsequently an Iso-c 3D image of the bone was acquired using Siemens ARCADIS Orbic C-arm. The image was automatically analyzed using custom software that determined the angle between the TEA and the reference pins (Fig 1). The difference between the angle read from the device and the planned angle was then used to correct the locations of the reference pins through a custom protractor device. Preparation of the bone was continued by placing the 4-in-1 jigs on the newly placed pins. Three-dimensional images of the bones after completion of the cuts were acquired, and the angle between the final cut surface and the TEA was determined.


Benjamin Snyder David Ayers Patricia Franklin

Purpose

Arthritis is the most common chronic illness in the United States. TKR provides reliable pain relief and improved function for patients with advanced knee arthritis. Total joint replacement now represents the greatest expense in the national healthcare budget. Surgical costs are driven by two key components: fixed and variable costs. Patient Specific Instruments™ (PSI, Zimmer, Warsaw, IN, USA) has the potential to reduce both fixed and variable costs by shortening operative time and reducing surgical instrumentation. However, PSI requires the added costs of pre-operative MRI scanning and fabrication of custom pin guides. Previous studies have shown reduction in operating room times and required instrumentation, but question the cost-effectiveness of the technology. Also, these studies failed to show improvement in coronal alignment, but call for additional studies to determine any improvement in clinical function and patient satisfaction. Our pilot study aims to compare the incremental PSI costs to fixed and variable OR cost savings, and compare meaningful patient and clinical outcomes between PSI and standard TKR surgeries.

Methods

This IRB approved, prospective, randomized pilot trial involves 20 TKR patients. Inclusion criteria includes: diagnosis of osteoarthritis, ability to undergo MRI, and consent for primary TKR. Following informed consent, patients are randomized to PSI or standard TKR. Patients randomized to PSI undergo pre-operative non-contrast MRI of the affected knee at least 4 weeks prior to surgery. Custom pin guides are prototyped from 3D pre-operative planning software customizable to individual surgeon and patient. All surgeries will be completed by a single surgeon (DA), using a medial parapatellar arthrotomy and Zimmer Nexgen™ implants. Surgical technique for PSI patients utilizes custom pin guides to determine placement of the femoral and tibial cutting guides, whereas an intramedullary femoral rod and extramedullary tibial guide are used in standard TKR patients.

Our pilot study will compare numerous intra-operative and post-operative variables between the two patient cohorts. Intra-operative variables include: bony cutting time, tourniquet time, total OR time, surgical instrumentation, and bony resection height. Post-operative variables include: instrument processing and sterilization, blood transfusion, pain medication usage, length of stay, complications (including hospital readmission), and patient reported outcomes (SF-36, WOMAC, and satisfaction) at 4 weeks, 6 months, and 1 year. Additional economic sensitivity analyses using hospital and national cost-to-charge figures will quantify the potential added revenue or costs of implementing the PSI system.


Michael B Cross Christina Esposito Anna Sokolova Reza Jenabzadeh Dennis Molloy Selin Munir Bernard Zicat William K Walter William L Walter

Introduction

Modularity is being increasingly used throughout the world for both primary and revision total hip arthroplasty. Recently there have been concerns of increased corrosion and fretting at the modular junctions. In the SROM® modular hip system, two modular junctions are the head-neck taper junction and the stem-sleeve taper junction. The aim of this study was to investigate corrosion at these junctions with the use of different bearing materials.

Methods

Between 1994 and 2012, fourty-two patients were revised with SROM® stems. Reasons for revision included aseptic loosening of the cup or stem (11), periprosthetic fracture (2), osteolysis (8), dislocation (13) and other reasons (7). One was revised for stem breakage, and this was excluded from this study. We examined 41 retrieved S-ROM® comprised of 6 metal-on-metal (MOM), 12 metal-on-polyethylene (MOP), 7 ceramic-on-polyethylene (COP) and 16 ceramic-on-ceramic (COC). The orientation for all components was marked at the time of revision surgery. Both the proximal sleeve/stem and the femoral head-neck modular junctions were examined under 10X magnification, and graded by two independent observers. The head tapers were divided into 4 regions, and graded using a previously published 3 point scoring system for fretting and corrosion damage (Goldberg et al, Kop et al), for a total corrosion damage score of 12. The SROM stems were also assessed at the sleeve/stem taper junction. Each stem was divided into 8 quadrants, and graded for corrosion and fretting using the same system as the taper. In addition to severity, we also quantified area of corrosion damage of the stem at the sleeve-stem junction from 0–3, which was multiplied by the severity of damage, to give a score out of 9 for each quadrant (maximum total score of 72 for the stem). The bearing type was unknown to the investigators, so the grading was done in a blinded fashion. Corrosion scores were divided by time to account for differences in time to revision.


Gregory Klingenstein Michael B Cross Christopher Plaskos Denis Nam Angela Li Andrew Pearle David J. Mayman

Introduction

The aim of this study was to quantitatively analyze the amount coronal plane laxity in mid-flexion that occurs in a well-balanced knee with an elevated joint line of 4 mm. In the setting an elevated joint line, we hypothesized that we would observe an increased varus and/or valgus laxity throughout mid flexion.

Methods

After obtaining IRB approval, nine fresh-frozen cadaver legs from hip-to-toe underwent TKA with a posterior stabilized implant (APEX PS, OMNIlife Science, Inc.) using a computer navigation system equipped with a robotic cutting-guide, in this controlled laboratory cadaveric study. After the initial tibial and femoral resections were performed, the flexion and extension gaps were balanced using navigation, and a 4 mm recut was made in the distal femur. The remaining femoral cuts were made, the femoral component was downsized by resecting an additional 4 mm of bone off the posterior condyles, and the polyethylene was increased by 4 mm to create a situation of a well-balanced knee with an elevated joint line. Real implants were used in the study to eliminate any inherent error or laxity in the trials. The navigation system was used to measure overall coronal plane laxity by measuring the mechanical alignment angle at maximum extension, 30, 45, 60 and 90 degrees of flexion, when applying a standardized varus/valgus load of 9.8 [Nm] across the knee using a 4 kg spring-load located at 25 cm distal to the knee joint line (Figure 1). Coronal plane laxity was defined as the absolute difference (in degrees) between the mean mechanical alignment angle obtained from applying a standardized varus and valgus stress at 0, 30, 45, 60 and 90 degrees. Each measurement was performed three separate times.

Two tailed student t-tests were performed to analyze whether there was difference in the mean mechanical alignment angle at 0°, 30°, 45°, 60°, and 90° between the well balanced scenario and following a 4 mm joint line elevation with an otherwise well balanced knee.


Bryan J McEntire Alan Lakshminarayanan B. Sonny Bal Thomas Webster Batur Ercan Deborah Gorth

Objective

Superior bone ingrowth and resistance to bacterial infection are ideal for orthopaedic implants. We compared new bone formation, strength of bone bonding, and infection rates between silicon nitride ceramic (Si3N4; abbreviated SiN), medical-grade PEEK (PEEK), and titanium (Ti) in rat calvariae. PEEK and Ti are used in spinal and arthroplasty implants respectively, while SiN is a non-oxide ceramic used in spinal implants for the past 4 years.

Methods

Specimens of 10 mm × 10 mm by 1.75 mm size were implanted into experimental calvarial defects in 2-year old Wistar rats using standard surgical techniques (n's: SiN=48; PEEK=24; Ti=24). One group of animals was immediately inoculated with 1 × 104 Staphylococcus epidermidis; control animals received saline only. After sacrifice at 3 days, 7 days, 14 days, and 3 months post-inoculation (n=4 rats per time period), one calvarial sample each for PEEK and Ti, and two samples for SiN (per bacterial condition and time point) were retrieved for histology; remaining samples were used for sample push-out testing with a Micro Tester 5848 (Instron) with a 1-kN load cell, using published techniques. New bone formation was measured with tetracycline double-labeling at 11 and 4 days before the 14-day and 3-month time periods.


Amar Mutnal John Bottros Robb Colbrunn Sam (Robert) Butler Alison Klika Wael Barsoum

Background

The acetabular labrum is an essential stabilizer of the hip joint, imparting its greatest effect in extreme joint positions where the femoral head is disposed to subluxation and dislocation. However, its stabilizing value has proved difficult to quantify. The objective of the present study was to assess the contribution of the entire acetabular labrum to mechanical joint stability. We introduce a novel “dislocation potential test” that utilizes a dynamic, cadaveric, robotic model that functions in real-time under load-control parameters to map the joint space for low-displacement determination of stability, and quantify using the “stability index”.

Methods

Five fresh-frozen human cadaveric hips without labral tears were mounted to a six-degree-of-freedom robotic manipulator and studied in 2 distinct joint positions provocative for either anterior or posterior dislocation. Dislocation potential tests were run in 15° intervals, or sweep planes, about the face of the acetabulum. For each interval, a 100 N force vector was applied medially and swept laterally until dislocation occurred. Three-dimensional kinematic data from conditions with and without labrum were quantified using the stability index, which is the percentage of all directions a constant force can be applied within a given sweep plane while maintaining a stable joint.


Hasan E. Baydoun Albert Yang Aliasgar H. Dalal Samuel J. Chmell

Background

With the projected 673% increase in total knee arthroplasties (TKA) through the year 2030 in the United States alone, arthrofibrosis will become one of the more commonly encountered challenges in orthopaedic surgery.

Methods

After obtaining Institutional Review Board approval we retrospectively reviewed the results of 19 patients with a mean age at the time of surgery of 55.4 years (41–83) who underwent arthroscopic lysis of adhesions (ALOA) for arthrofibrosis at a minimum of 3 months after primary total knee arthroplasty by a single surgeon (SJC) at a single institution. All patients underwent a standardized adhesiolysis in the operating room. All patients had a minimum of 6 months follow up. All patients underwent arthroscopic lysis of adhersions for restricted range of motion (ROM) after failing aggressive physical therapy. We defined restriction in ROM as any extension lag >5°, and flexion ≤90°. Eight patients underwent manipulation under anesthesia for ROM less than 90° after ALOA.


Christopher Paul Beauchamp Adam Schwartz Peter Rose Frank Sim Sam Harmson Steven Hattrup

Introduction

Extensive bone loss and poor residual bone quality can make implant fixation difficult to achieve in revision of failed megaprostheses. While newer porous components are available to address various periarticular cavitary and segmental defects, diaphyseal fixation remains challenging without resorting to cemented techniques, or cementless fully-coated stems that achieve fixation over long segments of bone. In cases of previous infection, it may be advantageous to avoid the use of such devices as they can be difficult to remove and may result in even greater bone loss if the infection were to persist. Compressive osseointegration technology has been become a valuable device in the management of these challenging situations.

Objectives

We aimed to evaluate the short-term results of compressive osseointegration when used for reconstruction of massive diaphyseal and segmental bone defects. We believe that compressive osseointegration provides predictable, strong endoprosthesis fixation in the short-term and that osseointegration can be evaluated radiogrphically.


Nicky Bertollo Todd Gothelf William Walsh

Introduction

Surgical drill-bits are used in a raft of procedures, from trauma, joint reconstruction to Arthroplasty. Drilling of bone is associated with the conversion of mechanical work energy into shear failure of bone and heat generation, causing a transient rise in temperature of hard and soft tissues. Thermal insults above 47°C sustained for one minute or more may cause osteonecrosis, reduced osteogenic potential, compromise fixation and influence tolerances with cutting blocks. Drill design parameters and operational variables have marked effects on cutting performance and heat generation during drilling. Dulling and wear of the cutting surfaces sustained through repeated usage can significantly reduce drill bit performance. Deterioration of cutting performance substantially increases the axial thrust force required to propel the cutting face through bone, compromising surgeon control during drilling and increasing the likelihood of uncontrolled plunging, cortical breakthrough and improper placement of holes as well as other jigs.

Methods

The drilling accuracy and skiving of 2.8 mm 3-fluted SurgiBit (Orthopedic Innovation (OI), Sydney, Australia) (Figure 1) was compared with a standard 2-fluted drill (Synthes) at 15, 30 and 45 degrees using a 4th generation Sawbone as well as bovine cortical bone. A surgical handpiece was mounted in a servo-hydraulic testing machine and the motion of the drill-bit confined to 2 degrees of freedom. The lateral force and skiving distance was measured (n=6 per drill per angle per testing medium). A new drill was used for each test. Wear performance over multiple drilling episodes (1, 10 and 100) was performed in bovine cortical bone. The surface characteristics of the cutting faces of the drills were assessed optically at 10x magnification and at higher magnifications (50, 100 and 500x) using an environmental electron microscope.


Ellen Beuckelaers Julien Verstraeten Hendrik Debacker Alexander Van Tongel Lieven De Wilde

Introduction

Humeral head subluxation in patients with cuff tear arthropathy (CTA) and in patients with primary arthrosis has been classified by Hamada and by Walch (type B). These classifications are based on 2D evaluation techniques (AP X-ray view, axial CT images). To our knowledge no 3D evaluation of the direction of humeral head subluxation has been described

Aim

To describe a reproducible 3D measuring technique to evaluate the direction of the humeral head subluxation in shoulder arthropathy


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Michael Beverly

Intraosseous pressure measurements (IOP) are not new. Several authors have struggled to interpret static IOP and to understand arthritis and osteonecrosis pathology. This work uses a combination of simple experiments in vivo to reassess bone and joint physiology. Joint replacement needs to take into account the hydrodynamic conditions that are present in bone. Intraosseous pressure measurements were carried out with vascular occlusion, activity and saline injection in experimental conditions and then in man during walking.

RESULTS

Basal IOP has a pulse wave and an underlying respiratory wave (RW).

IOP closely reflects systemic vascular changes.

Proximal arterial occlusion causes loss of IOP (IOPa) and pulse volume (PV).

Proximal vein occlusion causes a rise in IOP (IOPv) with preservation of PV and RW.

Physical loading raises IOP with preservation of PV and RW.

Load with arterial occlusion caused minimal rise in IOP.

Loading with venous occlusion caused an augmented rise in IOP with preservation of the PV.

Simultaneous recordings from the femoral head, condyle and upper tibia during vascular occlusion and loading show that the same effects occur at all sites.

Simultaneous recording from the femoral head, condyle and upper tibia during saline injection shows pressure is transmitted through bone but not across joints.

The Ficat bolus test destroys local circulation. Aspiration is better and preserves local perfusion.

Bone health at the needle tip is better assessed by IOPv – IOPa, the perfusion ‘bandwidth’.

Upper tibial pressure during standing, slow walking and fast walking shows large IOP changes in vivo.

There is probably a physiological subchondral bone blood pump.

Anatomical features are present which support this idea.

CONCLUSIONS

IOP measurement in isolation is meaningless. With arterial and venous occlusion, perfusion at the needle tip can be studied.

Compartment syndrome testing should be similar.

Subchondral bone is a compressible perfused sponge with a ‘pumped’ microcirculation.

Very high pressures arise in subchondral bone during activity.

There are protective modifications of the microcirculation.

Failure of subchondral circulation causes arthritis. Arthritis is mainly a ‘vasculo-mechanical’ disease. This work explains the spectrum of arthritis and osteonecrosis, and Perthes, caisson and sickle cell disease patterns. It explains why osteoporosis might protect against arthritis.


Roberto Binazzi De Zerbi Pavlidou Maria Nasta Guido

The present clinico-radiographical study evaluated the long term performance of a Ti-Al-V alloy cementless modular press-fit cups (Fitek™) having, on the outer surface, an oriented multilayer titanium mesh (Sulmesh™) with 65% tridimensional porosity and 2 fins applied to the outer surface. Fins were initially designed for anti-rotatory purposes but showed to give an excellent initial mechanical stability. Thus, in the following years, we have designed 2 other cups having 8 paper we compare the design and the results obtained with these 3 cups.

We have reviewed the first 100 consecutive FITEK cups implanted in 92 patients with an average FU of 9.7 years (range 9–11 years). Results were evaluated with the Harris score. We had 86 Excellent, 10 Good, 2 Fair and 2 Poor. In this series we always used 28 mm heads.

Dysplastic patients showed inferior results compared to arthritics patients in different parameters, as pain, limp, ROM (p < 0.05), putting socks and shoes (p < 0.05).

Radiographically, our cups were implanted in a fairly horizontal position (36.5° an average).

At the last FU radiolucent lines were present in 14 % of the cases, never progressive.

In no case we found a change of position of the cup, and in this series no revision was necessary.

Between 2005 and 2008 we have applied 140 consecutive Delta Fins cups with ceramic-on-ceramic articulation. The fins of this cup have a trapezoidal shape, with HA coating. The cup has an interference of 2 mm. The Delta ceramic insert allows the use of 32 or 36 mm heads.

Clinico-radiographical results were very good. One cup needed to be revised for aseptic loosening consecutive to a surgical error (undersizing)

The ADAPTIVE WINGS. Cup is an evolution of the 2 previous cups and is made of Porous Titanium with 8 fins having a triangular section, in order to increase their penetration into the acetabular cortical bone. The Delta ceramic insert allows the use of large heads (32, 36 and 40 mm). Preliminary clinico-radiographical results were excellent, with complete initial mechanical stability and great ROM due to the large ceramic heads.

The presence of fins on the outer surface of cementless cups enhances primary stability and fixation in dysplastic acetabula and the use of large ceramic heads improves ROM and subjective patients satisfaction.


Jan-M Brandt Leah Guenther Sean O'Brien Alex Vecherya Thomas Turgeon Eric Bohm

Femoral components with an oxidized zirconium-niobium (OxZr) gradient ceramic surface (Oxinium, Smith & Nephew, Memphis, TN) were introduced as an alternative to cobalt-chromium (CoCr) alloy femoral components for the purpose of PE wear reduction in total knee replacements [1]. In the present study, the surface damage and clinical performance of both CoCr alloy and OxZr femoral components were investigated. By matching CoCr alloy and OxZr femoral components for clinical factors, as done by Heyse et al. [2], the surface damage on retrieved CoCr alloy and OxZr femoral component was assessed. Twenty-six retrieved cobalt-chromium (CoCr) alloy femoral components were matched with twenty-six retrieved oxidized zirconium (OxZr) femoral components for implantation period, body-mass index, patient gender, implant type (cruciate ligament retaining/substituting), and polyethylene insert thickness. Detailed surface profilometry was performed on retrieved femoral condyles in areas that had not been damaged by gouging [3] with the specific purpose of investigating the in vivo wear behaviour of undamaged OxZr surface. In addition, the cumulative survivorships were calculated for patients who had received CoCr alloy or OxZr femoral components from our orthopaedic database. In order to identify factors that affect the clinical performance of CoCr alloy and OxZr femoral components, the findings from the retrieval analysis and the survivorship analysis were combined. The Rp, Rpm, and Rpk-values for the retrieved CoCr alloy femoral components were found significantly higher than the Rp, Rpm, and Rpk-values for the retrieved OxZr femoral components (p ≤ 0.031). The roughness parameters values (Ra, Rq, Rz, Rp, Rpm, Rpk, Rv, and Rsk) for the retrieved CoCr alloy femoral components were found significantly higher than the values of the new, never implanted CoCr alloy femoral components (p ≥ 0.001). The surface roughness was higher on the medial condyles than the lateral condyles of the retrieved CoCr alloy femoral components; such a difference was not observed on the retrieved OxZr femoral components. The OxZr bearing surface appeared to protect the femoral components from abrasive wear in vivo. At 8.5-years follow up, the cumulative survivorship for the CoCr alloy femoral components (98%) was not found to be statistically significantly different (p = 0.343, Breslow test) from the OxZr femoral components (97.5%). Therefore, OxZr femoral components appeared to possess low wear characteristics and could be particularly suitable for younger, heavier patients to ensure long-term durability.


Claire Brockett Catherine Hardaker John Fisher Louise Jennings

Introduction

Wear of polyethylene continues to be a significant factor in the longevity of total knee replacement (TKR). Moderately cross-linked polyethylene has been employed to reduce the wear of knee prostheses, and more recently anti-oxidants have been introduced to improve the long-term stability of the polyethylene material. This is the initial study of the wear of a new anti-oxidant polyethylene and a new TKR design, which has modified femoral condylar geometry.

Materials and Methods

The wear of a new TKR the Attune knee was investigated using a physiological six station Prosim knee wear simulator (Simulator Solutions, UK). Six mid-size Attune fixed bearing cruciate retaining TKRs (DePuy Inc, Warsaw, USA) were tested for a period of 6 million cycles. The inserts were manufactured from AOX™, a compression moulded GUR1020 polyethylene incorporating Covernox™ solid anti-oxidant. The AOX polymer was irradiated to 8M Rad, to give a moderately cross-linked material.

High and intermediate kinematics, under anterior-posterior displacement control were used for this study (McEwen et al 2005). The maximum femoral axial loading was 2600N, with flexion-extension of 0 to 58°, an anterior-posterior displacement of 0–10 mm for high kinematics and 0–5 mm for intermediate, and an internal-external rotation of ±5°. The lubricant was 25% (v/v) calf serum supplemented with 0.03% (v/v) sodium azide solution in deionised water, as an antibacterial agent, and was changed approximately every 0.33 Mc. Wear was assessed gravimetrically and moisture uptake was assessed using unloaded soak controls. Volumetric wear was calculated using a density of 0.94 mg/mm3, and compared with a previous study examining the Sigma XLK TKR design which uses moderately crosslinked polyethylene which is in current clinical use (Brockett et al 2012).


Danilo Bruni Francesco Iacono Mirco Lo Presti Giovanni Raspugli Bharat Sharma Maurilio Marcacci

INTRODUCTION

The literature suggests a survivorship of unicompartmental knee arthroplasties (UKA) for spontaneous osteonecrosisof the knee range from 93% to 96.7% at 10 to 12 years. However, these data arise from series reporting 23 to 33 patients, jeopardizing meaningful conclusions.

OBJECTIVES

Our purpose is to examine a long term survivorship of UKA's in a larger group of patients with SPONK, along with their subjective, symptomatic and functional outcome; to determine the percentage of failures and the reasons for the same in an attempt to identify relevant indications, contraindications, and technical parameters in treating SPONK with a modern implant design.


Yoon Jong Chang Yong-Sik Kim Young Wook Lim Joo-Hyoun Song Soon Yong Kwon

Introduction

To minimize leg length discrepancies (LLD), preoperative measures are taken using the PACS; the head center to the proximal end of the lesser trochanter distance (HLD) of the opposite side of the operating limb are calculated, while during operation, the modular neck selection is adapted to equal the opposing limb's length.

The purpose of this study was to see whether the HLD method would show far less occurrences of LLD, in comparison to the conventional method(preoperative templating and shuck test).

Method

349 (412 hips) patients who had undergone THRA were divided into two groups based upon which methods they had used to equalize limb length during operation: (1) HLD method, and (2) conventional methods. Six months after surgery, using the PACS system, LLD's of the two groups were compared.


Yan Chen Shingo Kurosu Yungping Lee Hiroaki Matsumoto Yuichiro Koizumi Akihiko Chiba

Introduction

Metal-on-metal (MOM) hip joints have regained a favor in arthroplasty since they own excellent wear resistance. In this study, wear tests by using a hip joint simulator were conducted with MOM bearings of specified 40 mm femoral heads. The influence of clearance on the wear behavior was investigated. Furthermore, an optimized radial clearance was estimated by lubricant film thickness and contact pressure analysis.

Materials and methods

Co-27Cr-5Mo-0.13N-0.05C (hereafter CCMN) alloy (mass %) was used. The ingots were vacuum induction melted, homogenized and hot forged successively. The microstructure shows equiaxed crystal grains with abundant annealing twins but no carbides.

Two groups of bearings, indicated as cr 1 and cr 2, were designed. The radial clearances for cr 1 and cr 2 were 37.9 and 148.7 μm, respectively. Wear tests were conducted in a hip joint simulator (INSTRON 8870) in Hanks' solution at 37±2°f. The force and 3-axile angle of movement were applied on the articulation according to ISO 14242-1 for 1.5 million cycles (Mc).

The contact pressures on the hip joints were also analyzed by using ABAQUS. The femoral heads were set 40 mm with radial clearances of 0–200 μm. Half models were set up and only the maximum force of 3 kN converted as pressure was applied as boundary condition.


Dong Chen Nicky Bertollo Ralph Stanford Wade Harper William Walsh

Aim

Cementless prosthesis is one of the major bone-implant interface fixation methods in total joint replacement. Grit blasted surface, hydroxyapatite coated surface and plasma sprayed metallic porous coating have been popularly used. The latter has demonstrated higher bone implant mechanical stability in previous laboratory study in early and middle stages. However, question remains what the mechanism is to make it performing better and how to improve them further. This study is designed to examine the mode of failure in bone-implant interface in a sheep model.

Method

Plasma sprayed porous coated (TiPL); hydroxyapatite (HA) coated and and grit blasted (TiGB) titanium implants were examined in the study. Each type has 36 specimens. Implants were inserted into cortical bones in a press-fit fashion in a total of 22 sheep bilateral hind limbs. Specimens were retrieved at 4 weeks and 12 weeks. Push- out testing was performed to just reach ultimate failure. Failed bone-implant interface were investigated by histology and BSEM. The percentage of failure at bone-coating interface, bone itself fracture, coating itself failure, and coating-substrate dissociation were measured by BSEM.


Dong Chen Nicky Bertollo Wade Harper Ralph Stanford William Walsh

This study was performed to compare the mechanism of bone-implant integration and mechanical stability among three popularly used cementless implant surfaces. Plasma sprayed porous surface (TiPL), grit-blasted rough surface (TiGB), and hydroxyapatite coated implant surface (HA) were tested in a sheep model at 4 and 12 weeks. The integration patterns were investigated using histology, histomorphometry, and mechanical strength by push-out test. All three groups demonstrated early bone ongrowth on their surfaces, with much of the ongrowth resembling contact osteogenesis. TiPL group showed bone anchorage into porous coating with new bone ingrowth into the pores. HA group revealed small cracks at its coating at 12 weeks time point. Plasma sprayed porous surface also demonstrated its superior mechanical stability maybe reinforced by its bone anchorage, whearas, HA surface exhibited higher osteoconductivity with highest ongrowth rate.


Samuel MacDessi Darren Chen Bradley Seeto Gregory Wernecke

AIM

Tibial component design has be been scrutinized in a number of studies in an attempt to improve tibial coverage in total knee arthroplasty. However, very few have controlled for both component rotation and resultant changes to posterolateral tibial tray overhang and posteromedial underhang. We hypothesize that asymmetrical tibial components can provide greater coverage than symmetrical trays without increasing overhang.

METHODS

The 6 most commonly used tibial trays on the Australian Joint Registry (2009) were superimposed on MRI slices of normal knees to assess tibial component overhang, underhang and percent coverage. Rotational alignment in this analysis was based upon the line joining the junciton of the medial and middle 1/3 of the patellar tendon and the PCL insertion.


Akihiko Chiba Shingo Kurosu Yuichiro Koizumi Hiroaki Matsumoto Yungping Lee

Rapid manufacturing using laser beam and/or electron beam has been applied to fabrication of artificial hip and knee joints in quite recent years. In the electron beam melting (EBM) method, the high energy electron beam effectively melts the metal powder without creating flaws such as porosities or inclusions of oxide particles during building. Thus it is found that EBM technique for rapid manufacturing of artificial hip and knee joints processes a higher possibility as the next-generation methodology for fabrication of the medical devices such as hip and knee joints. In the present study, we focus on the EBM technique. The microstructures and mechanical properties of Co-29Cr-6Mo alloy with C and N additions, produced by using EBM method, were studied using X-ray diffraction, electron back scatter diffraction, transmission electron microscope (TEM), Vickers hardness tests, and tensile tests, focusing on the influences on the build direction and the various heat treatments after build. It is found that the microstructures for the as built specimens were changed from columnar (Fig. 1a) to eqiaxed grain structure (Fig. 1c) with average grain size of approximately 10–20 μm due to the heat treatment employing the reverse transformation from a lamellar (hcp + Cr2N) phase to an fcc phase. Our results will contribute to the development of biomedical Ni-free Co–Cr–Mo–N-C alloys, produced by EBM method, with refined grain size and good mechanical properties, without requiring any hot workings.

Fig. 1 Inverse pole figure (IPF) maps of microstructure of samples produced by EBM method, taken by EBSD. (a) as-built, (b) after aging treatment, (c) after reverse transformation heat treatment (RT-HT).


Yoon Je Cho Joo-Hyun Lee Young Soo Chun Kee Hyung Rhyu Sangjoon Kwak Ye Yeon Won Myung-Chul Yoo

Purpose

In general, the amount and rate of linear wear are associated with femoral head size in the conventional UHMWPE acetabular liner. The smaller the femoral head, the higher the linear wear rate. The aim of this study is to verify the relationship between wear rate and femoral head size and the polyethylene cup thickness.

Materials and Methods

We conducted a retrospective review of all patients who had undergone primary cementless total hip arthroplasty using the conventional UHMWPE (HGP2) acetabular liner between July 1992 and December 2002. 128 hips (34 hips of female, 94 hips of male) of 64 patients who had 28 mm femoral head with different polyethylene acetabular linear thickness and 102 hips (41 hips of female, 61 hips of male) of 81 patients with 22 mm femoral head were included. Patients were assessed clinically and radiographically at postop 6 weeks, 3 months, 6 months and annually thereafter. Clinical assessment was performed using Harris Hip Score. Radiographic analysis included measurement of acetabular component position, polyethylene wear using a validated radiographic technique (Dorr method). Their mean age at the time of operation was 45.3 (24–81) years old and mean follow-up period was 10.8 (96–144 months) years.


Su Hyun Cho Hyung Lae Cho

Purpose

To report clinical results and demonstrate any posterior femoral translation (PFT) in medial rotation total knee arthroplasty (TKA) of posterior cruciate ligament (PCL) retaining type.

Materials and Methods

A prospective study was performed upon thirty consecutive subjects who were operated on with medial rotation TKA of PCL retaining type (Advance® Medial Pivot prosthesis with ‘Double High’ insert; Wright Medical Technology, Arlington, TN, USA) (Fig. 1). between March 2009 and March 2010 and had been followed up for a least 2 years. Inclusion criteria were age between 60 and 75 years and primary degenerative joint disease of knee graded as Kellgren Lawrence grade III or higher. Exclusion criteria were age under 60 years, any inflammatory joint disease including rheumatoid arthritis, early stage of primary degenerative joint disease of knee or any history of previous osteotomy around knee. Clinically, the knee society knee score and function score were used to evaluate pain and function. At last follow-up, all subjects performed full extension, thirty degree flexion and full active flexion sequentially under fluoroscopic surveillance. In each of these lateral radiographs, anteroposterior(AP) condylar position was pinpointed and the magnitude of PFT was determined by degree of transition of AP condylar position from full extension to full active flexion radiograph (Fig. 2 A–B). Statistical methods used were paired t-test, Pearson correlation, Steadman rank correlation and regression analysis. Component migration and radiolucent line were also observed.


Henry Clarke

Introduction

CT based systems that are used to create custom components and custom cutting guides in total knee arthroplasty (TKA) have variable methods for accounting for the thickness of remaining cartilage that may influence component sizing and bone resection. Little information has been published about the thickness of this cartilage, especially on the posterior femoral condyles. Failure to account for this cartilage may lead to under-sizing of the femoral component, or a reduction in the posterior condylar offset that may adversely affect flexion after TKA.

Methods

This IRB approved, retrospective study included 140 consecutive patients who underwent primary TKA. The medial and lateral posterior condylar bone cuts were performed in the usual manner with mechanical instruments. The resected specimen was sectioned in the sagital plane and the cartilage thickness was measured at the mid portion to the nearest millimeter.


Henry Clarke Adam Bloemke Adam Schwartz

Introduction

While prosthesis survival in Total Knee Arthroplasty (TKA) exceeds 90% at 10 year, failures do occur. One area of concern has been the potential for metal allergy or metal sensitivity causing persistent pain, swelling or early failure of the implant in some patients. Definitive tests for diagnosing metal allergy and metal sensitivity have not been developed and this field remains controversial. In most cases where metal sensitivity is a concern, metals such as Chromium and Nickel are implicated. Despite the lack of good diagnostic tests for identifying these patients, several orthopedic prosthesis manufacturers have developed implants made of Titanium or ceramic designed for use in patients where concerns exist regarding metal allergy. In the absence of good diagnostic tests, use of these devices in patients that self identify is one option. To date, little information has been presented about the incidence of self reported metal sensitivity in patients undergoing joint replacement. This study was undertaken to determine the incidence of self reported metal allergy or sensitivity in patients undergoing total knee arthroplasty.

Methods

An IRB approved, retrospective chart review was performed in a consecutive series of 194 patients who had undergone TKA at one institution, with one surgeon. Self reported metal sensitivity and allergy had been routinely elicited from each individual who had not undergone implantation of a previous metallic device, during pre-operative consultation.


Fabio Conteduca Fabio D'Angelo Jacopo Conteduca Raffaele Iorio Andrea Ferretti

Alpha Lipoic Acid (L.A.) is an effective natural antioxidant discovered in the human body in 1951 from L.J. Reed and I.C. Gunslaus from liver. It is inside broccoli, spinach and red meats, especially liver and spleen. Actually it is largely used as antioxidant in antiaging products according to the low toxicity level of the product.

The present study take into consideration the possibility to reduce oxidation of medical irradiated UHMWPE GUR 1050, mixing together polyethylene powder and Alpha Lipoic Acid powder.

The study is composed of two parts.

Part 1 Thermostability of alpha lipoic acid during polyethylene fusion

Part 2 detection of oxygen level in artificially aged irradiated polyethylene

Solid pieces were made with Gur 1050 powder (Ticona Inc., Bayport, Tex, USA) and mixed with Alpha Lipoic Acid (Talamonti, Italy, Stock 1050919074) 0, 1% and gamma ray irradiated with 30 kGy (Isomedix, Northborough, MA).

An oven (80° Celsius) was used to produce an aging effect for 35 days in the doped and control samples (Conventional not doped polyethylene). This process simulate an aging effect of 10 years into the human body.

THERMAL STABILITY: a Fourier Transfer Infra Red (FTIR) test was made in pieces molded in a cell at 150° and 200°Celsius and pressure of 200 MPa comparing to the UHMWPE powder mixed with alpha lipoic acid. The presence of Alpha Lipoic Acid in the polyethylene was found at any depth in the manufacts.

figure 1: A Pure Lipoic Acid. B Lipoic Acid + UHMWPE melted 150° C. Lipoic Acid + UHMWPE melted 200° C° (A And B spectra subtracted UHMWPE)

OXIDATION: After 5 weeks at 80° Celsius in a oven (ASTM standard F-2003-02)A FOURIER TRANSFER INFRA RED TEST (FTIR) was made in the superficial layer and deeper on the undersurface of doped 0.1% and conventional UHMWPE.

The antioxidation limit is defined as the ratio of the area under 1740 cm/−1 carbonyl and 1370 cm/−1 Methylene absorbance peaks.

In conventional UHMWPE oxidation is detected on the surface and decreases in the deeper layers down to zero under 1500 Micron Fig 2.

figure 2 Pure polyethylene: A Surface, B 1500 Micron, C 3000 Micron

In the doped UHMWPE, FTIR demonstrate a very low oxidation limit on the surface and at any depth, comparing to conventional UHMWPE Fig 3.

figure 3 Doped UHMWPE A surface, B 700 micron deept, C 1700 micron deept

The examples show that Lipoic Acid is effective as antioxidant in irradiated UHMWPE and it is stable with respect to thermal treatment.


Praveen Vijaysegaran George Banic Sarah Whitehouse Ross Crawford

There has been much discussion and controversy in the media recently regarding metal toxicity following large head metal on metal (MoM) total hip replacement (THR). Patients have been reported as having hugely elevated levels of metal ions with, at times, devastating systemic, neurolgical and/or orthopaedic sequelae.

However, no direct correlation between metal ion level and severity of metallosis has yet been defined. Normative levels of metal ions in well functioning, non Cobalt-Chrome hips have also not been defined to date.

The Exeter total hip replacement contains no Cobalt-Chrome (Co-Cr) as it is made entirely from stainless steel. However, small levels of these metals may be present in the modular head of the prosthesis, and their effect on metal ion levels in the well functioning patient has not been investigated.

We proposed to define the “normal” levels of metal ions detected by blood test in 20 well functioning patients at a minimum 1 year post primary Exeter total hip replacement, where the patient had had only one joint replaced.

Presently, accepted normal levels of blood Chromium are 10–100 nmol/L and plasma Cobalt are 0–20 nmol/L. The UK Modern Humanities Research Association (MHRA) has suggested that levels of either Cobalt or Chromium above 7 ppb (equivalent to 135 nmol/L for Chromium and 120 nmol/L for Cobalt) may be significant. Below this level it is indicated that significant soft tissue reaction and tissue damage is less likely and the risk of implant failure is reduced.

Hips were a mixture of cemented and hybrid procedures performed by two experienced orthopaedic consultants. Seventy percent were female, with a mixture of head sizes used.

In our cohort, there were no cases where the blood Chromium levels were above the normal range, and in more than 70% of cases, levels were below recordable levels. There were also no cases of elevated plasma Cobalt levels, and in 35% of cases, levels were negligible.

We conclude that the implantation with an Exeter total hip replacement does not lead to elevation of blood metal ion levels.


Joseph Daniel Hena Ziaee Chandra Pradhan Derek McMinn

Introduction

Wear and corrosion of metal-on-metal (MM) bearings releases (a) soluble metal ions which collect locally and pass into the systemic circulation and (b) insoluble particles which undergo local deposition and lymphoreticular dissemination. Debris-related failures from osteolysis, metallosis and pseudotumours warrants revision of these MM bearing devices to non-MM bearing arthroplasties with the expectation that both the systemic and local effects will be reversed with time since the source of metal ion release is removed.

The purpose of the present study is to determine (a) whether metal ion levels in blood and urine decrease after revision of a MM bearing arthroplasty to a non-MM bearing device and (b) the rate at which this decrease is effected.

Methods

Blood and urine levels of cobalt and chromium ions are studied prospectively over two years in 15 patients whose MM resurfacings were revised to cross-linked polyethylene containing total hip replacements (THRs). Specimen collection was started before and periodically after the revision at 2, 4 and 6 days and 2 months, 6, 12 and 24 months after operation. None of the patients had other MM devices or compromised renal function.


Joseph Daniel Hena Ziaee Chandra Pradhan Derek McMinn

Introduction

Hip simulator studies show that metal-on-metal bearing wear can be reduced by reducing the diametral clearance of the bearing. We present the six-year follow-up results of a prospective clinico-radiological and metal ion study in patients with a low clearance metal-metal surface arthroplasty. The results are compared to published results of similar design bearings with conventional clearance.

Methods

Twentysix male patients (mean age 55 years, mean BMI 26) who received a 50 mm bearing resurfacing (radial clearance 50μm) were included in an ongoing clinico-radiological and metal ion study. Urine/blood specimens were obtained before and periodically after hip resurfacing. Patients were also assessed with Oxford Hip Scores and Harris Hip Score questionnaires. Two hips were excluded during follow-up, one for revision and another for contralateral hip arthroplasty.


Hena Ziaee Joseph Daniel Chandra Pradhan Derek McMinn

Introduction

Modern metal-on-metal bearing resurfacings have been in use for nearly two decades. Local and systemic metal ion exposure continues to cause concern. We could not find a prospective metal ion study in such patients with a 10-year follow-up. This is the first ten year prospective study of metal ion levels in blood and their release in urine following hybrid fixed metal-on-metal surface arthroplasty.

Methods

Twenty six patients were included in an ongoing longitudinal metal ion study of patients with unilateral metal-on-metal hip resurfacings. Three of them were excluded due to subsequent contralateral resurfacing and one has relocated abroad. Cobalt and chromium levels were assessed in 12 hour urine collections before and periodically after operation (5 days to 10 years) using high resolution plasma mass spectrometry. Mean age at operation was 53 years and mean BMI 27.9.


Hena Ziaee Chandra Pradhan Joseph Daniel Derek McMinn

Introduction

Metal-metal surface replacement (MoMSRA) continues to be used in young women. Systemic metal ion release and its effects cause concern. Do metal ions crossing the placenta in pregnant women have potential mutagenic effects? The hypothesis is that metal ions pass freely through the placenta and there is no difference in maternal and cord metal levels.

Methods

This is a controlled cross-sectional study of women with MoMSRA. (n = 25, 3 bilateral, mean age 32 years, time from implantation to delivery 60 months). The control group consisted of 24 subjects, mean age 31 years, with no metallic implant and not receiving cobalt/chromium supplements. No patient was known to have renal failure. Whole blood specimens were obtained before delivery and before any infusion or transfusion, and cord blood specimens immediately after delivery.


Carlo Felice De Biase Marco Delcogliano Raul Marco Polo Mario Borroni Alessandro Castagna

INTRODUCTION

The aim of this retrospective study is to evaluate clinically and radiographically the effectiveness of implanting an eccentric glenosphere and if a correct glenosphere positioning would avoid the occurrence of notching.

METHODS

since 2006 40 patients with shoulder eccentric osteoarthritis were treated with reverse shoulder arthroplasty with a 36 mm eccentric glenosphere. We have selected 25 patients, with a minimum follow up of 24 months. The patients were clinically evaluated with the Constant score and SST and with X-ray, MRI and/or CT before and after surgery. At the follow up we evaluated the presence or absence of notch, and we measured the PSNA (prosthesis-scapular neck angle), the DBSNG (distance between the scapular neck angle and glenosphere), the PGRD distance (peg glenoid distance). Stastistical analysis was performed with a paired t test.


Carlo Felice De Biase Marco Delcogliano Raul Marco Polo Mario Borroni Alessandro Castagna

Purpose

Reverse shoulder prosthesis may lead to scapular notching, caused by attrition of the upper humeral component with scapular neck. We compared the clinical and radiographic results obtained with a SMR prosthesis, which allows a concentric or an eccentric glenosphere to be applied.

Patients and methods

67 patients, mean age 73 years, were treated with reverse prosthesis using concentric and eccentric glenosphere. In patients with concentric glenosphere, the glenosphere extended about 4 mm below the glenoid. The eccentric glenosphere protected the upper glenoid neck by its inferior prolongment. Patients were followed for a mean of 33 months. At final F-U the Constant Score (C.S.) and the score with the Simple Shoulder test (S.S.T.) were calculated. Radiographs were obtained to evaluate the presence of scapular notching, psna (prosthesis-scapular neck angle), pgrd (peg- glenoid rim distance) and DBSNG (distance between scapular neck and glenosfere). Included in this study were patients, as much homogeneous as possible by age and pathology, 25 with concentric (Group I) and 30 with eccentric (Group II) glenosphere, who had a minimum F-U of 24 months. Statistical analysis was performed with a paired test.


Daniel C.J. De Kam Vincent J.J.F. Busch Jean W.M. Gardeniers Rene P.H. Veth B. Willem Schreurs

Introduction

Total hip arthroplasties in younger patients often requires revision because these patients frequently have acetabular deficiencies, which hamper proper implantation of the cup essential for good long-term prosthesis survival. For 30 years, we have used a biological acetabular-reconstruction technique with bone-impaction grafting in all patients <50 years with an acetabular deficiency at surgery, always in combination with a cemented total hip implant.

Methods

We evaluated all 150 consecutive patients (177 hips) < 50 years with an acetabular reconstruction by bone-impaction grafting surgically-treated from 1978–2004 at our clinic. Mean follow-up was 10.3 (range, 2.0–28.3) years with no patient lost to follow-up. Mean index surgery age was 38.1 (range, 16–49) years. Clinical, radiological, and statistical analysis of all patients was performed.


Daniel C.J. De Kam Jean W.M. Gardeniers Rene P.H. Veth B. Willem Schreurs

Background

Surgeons always must take into account that a primary total hip arthroplasty (THA) in a young patient will be revised in the future, this because of the long life expectancy of young THA patients and the limited durability of prosthetic implants in these patients. Therefore we would like to accentuate the revisability of a primary THA in this specific and high demanding patient population.

Methods

343 consecutive THA in 267 patients under the age of 50 years were evaluated. We also assessed the results of the revised THA (n=53) within the same population. Clinical, radiographical and survival of primary and revision THA were evaluated.


Ivan De Martino Vincenzo De Santis Carlo Fabbriciani Giorgio Gasparini

Pure tantalum has been proposed in orthopaedic surgery. Its chemical and physical properties have been widely studied in the past. From pure tantalum is obtained a spongy structure (Trabecular Metal Technology: TMT) that shows a full thickness porosity which is 2–3 times higher compared to other surfaces available for bone ingrowth with a three-dimensional porous arrangement in rough trabeculae. Pores (average diameter of 650 mm) are fully interconnected and represent 75–80% of the whole volume. TMT acetabular components have an elliptical shape and have an irregular external surface which both allow an optimal mechanical fit.

We retrospectively reviewed 212 cases of monoblock porous tantalum acetabular cup (Hedrocel, Stratec) implanted between 1999 and 2003 in a single centre with a minimum follow-up of 9–10 years; There were 98 men and 114 women, with an average age of 65 years. They all underwent primary or revision total hip arthroplasty or to acetabular component revision alone. In all patients a monoblock porous tantalum acetabular component with polyethylene directly compression molded into cup, with or without peripheral holes for screws, was implanted. In all primary procedures the same femoral stem (Synergy, Smith and Nephew) was implanted.

All patients were evaluated with a clinical examination (Harris Hip Score: HHS) and with standard radiographs of the pelvis preoperatively and 1, 3, 6 months and yearly postoperatively. The stability of the acetabular cup was determined by modified Engh's criteria.

The HHS score improved from 42 preoperatively to 94 after one year; at 13 years follow-up it was 95. The subjective outcome was widely satisfying, with the majority of patients experimenting good functional recovery and return to daily activities. Osteointegration of the acetabular component was present in all X-rays controls at one year after surgery. All post-operative evidence of residual bone loss (geodes, bone defects in revisions and in displasia) were no more radiographically evident after 1 year postoperatively as the host bone quickly filled these gaps. We did not observe osteolysis nor progressive radiolucent lines at the latest follow-up. None of the cups was revised, except 3 cases, revised for infection.

Both clinical and radiographic results are the same or even superior to those of coated implants. Our experience confirms that trabecular metal tantalum cups can avoid the formation of bone-implant interface membrane and consequently can avoid implant loosening. The most important advantages of TMT monoblock cups are: no potential for polyethylene backside wear, prevention of loosening and osteolysis, increased early fixation via friction, improved late biological stability, maximum bone-implant contact. High biocompatibility of porous tantalum and its elastic modulus very close to bone influence positively earlier and wider osteointegration of the implant. Larger series are needed to confirm the positive our preliminary results.


Parthiv Rathod Ajit Deshmukh Amar Ranawat Jose Rodriguez

INTRODUCTION

Osteoarthritis (OA) of the hip and the knee has been found to affect sexual activity. Few retrospective studies have investigated the role of total hip replacement on sexual function. We designed a prospective study to evaluate the influence of total hip arthroplasty (THA) and total knee arthroplasty (TKA) on the physical and psychological aspects of sexuality of patients.

METHODS

Between April 2009 and April 2011, patients under 70 years of age scheduled for primary THA or TKA for OA were invited to anonymously participate in this study. All patients were recruited from the practices of 2 arthroplasty surgeons (at the same institution) by mailing the 2 questionnaires, 2 pre-paid self-addressed envelopes and a cover letter. Patients were instructed to mail back the pre-operative questionnaire prior to surgery and the post- operative questionnaire 6 months after surgery. Enrolled patients were also contacted after 1 year of surgery to fill a similar questionnaire. Responses were identified only by a unique code number on the questionnaire.


B. Devadasan A. Hafiz D. Harichandra

Introduction

Core decompression is used in precollapse lesions to forestall disease progression in avascular necrosis (AVN) of femoral head (FH). The author reports a new technique using reverse bone graft technique to effectuate core decompression.

Aim

To prevent precollapse in Ficat Type 1&2 and revascularization using synthetic bone graft material.


B. Devadasan S.A. Asgari S Mansor AM Hamouda H. Singh

Stress shielding of the proximal femur occurs in stemmed implants. Resurfacing implant does not invade the intramedullary region. We studied the stress patterns in conventional and nonstemmed designs.

Methods

FE model geometry was based on standard femur from the international Society of Biomechanics Mesh Repository. Loading simulated for one- legged stance with body weight of 826 N. 2 regions were defined, R1 (40 mm from tip of head) and R2 41 mm–150 mm) of the intramedullary part of the stemmed model's interface with bone. 2 different loading conditions bending and torsion were compared for stress and strain. The FE model was solved with ANSYS version 6.1 on a single processor NT station.

Results

With conventional implants, stem shields cortical bone from being loaded. In nonstemmed implants, Von Misses stress contours show a similar distribution as intact bone, transferring loads to the cortical shell but with higher stresses and a maximum displacement of 17.39% higher than that of intact bone. 15–23 mm proximal to R2 and around 110 mm, region of the stem tip, there were higher stress and strain concentrations.


B. Devadasan W. Loo J Johari

Most studies about hemi-arthroplasty of hip have focused on clinical aspects. Design features of various implants of hemi-arthroplasty have not been studied extensively. The aim was to investigate the relationships between radiological variables and possible mode of failure in various hemiarthroplasty implants in intracapsular neck of femur fractures.

A retrospective review of 42 hemi hip arthroplasties, Austin Moore and Thompson prosthesis by Biomet, Medical Product Service (Tipsan) and Smit Medimed (SMPL) used in our hospital. Controversy exists between indication for a particular design in an unselected series of patients once excluding the choice of cementing or uncementing the prosthesis. In monoblock prosthesis not only the head-neck region affects the stability but also the stem fit in proximal femur.

Surgeon preference to technique and approach excluded. Premorbidly all patients were mobilising independently. 5 criteria reviewed. 1) head size of prosthesis 2) neck length 3) prosthesis stem shaft angle 4) stem-cortical distance ratio and 5) shape of the femoral canal as classified by Dorr. Head size compared in AP views of involved hip and normal head size compared with that of prosthesis. A difference <2 mm or >3 mm indicative of incorrect size. Neck length measured by the vertical distance from center of head to superior aspect greater trochanter was zero. A range of +/− 5 mm was acceptable. Neck shaft angle with a difference of >5 degrees was indicative of varus position of the stem. Canals of the proximal femoral categorized as a) stove pipe b) champagne c) fluted varieties radiologically. X-ray magnification corrected. All measurements were done on immediate postoperative radiographs.

Stability of various design features of straight stemmed and curved implants are dependant on the anterior bowing angle and canal ratio of femur to prosthesis. A prospective study with CT from selected shapes of the proximal femoral is being carried out. Inappropriate head size as reported by Thompson or neck length was related to incidence of dislocation resulting in failure. Our findings emphasise importance of careful selection of a particular implant design towards the morphology of the femoral canal.


Alexander Dickinson Andrew Taylor Anne Roques Martin Browne

Representative pre-clinical analysis is essential to ensure that novel prosthesis concepts offer an improvement over the state-of-the-art. Proposed designs must, fundamentally, be assessed against cyclic loads representing common daily activities [Bergmann 2001] to ensure that they will withstand conceivable in-vivo loading conditions. Fatigue assessment involves:

cyclic mechanical testing, representing worst-case peak loads encountered in-vivo, typically for 10 million cycles, or

prediction of peak fatigue stresses using Finite Element (FE) methods, and comparison with the material's endurance limit.

Cyclic stresses from gait loading are super-imposed upon residual assembly stresses. In thick walled devices, the residual component is small in comparison to the cyclic component, but in thin section, bone preserving devices, residual assembly stresses may be a multiple of the cyclic stresses, so a different approach to fatigue assessment is required.

Modular devices provide intraoperative flexibility with minimal inventories. Components are assembled in surgery with taper interfaces, but resulting residual stresses are variable due to differing assembly forces and potential misalignment or interface contamination. Incorrect assembly can lead to incomplete seating and dissociation [Langdown 2007], or fracture due to excessive press-fit stress or point loading [Hamilton 2010]. Pre-assembly in clean conditions, with reproducible force and alignment, gives close control of assembly stresses. Clinical results indicate that this is only a concern with thick sectioned devices in a small percentage of cases [Hamilton 2010], but it may be critical for thin walled devices.

A pre-clinical analysis method is proposed for this new scenario, with a case study example: a thin modular cup featuring a ceramic bearing insert and a Ti-6Al-4V shell (Fig. 1). The design was assessed using FE predictions, and manufacturing variability from tolerances, surface finish effects and residual stresses was assessed, in addition to loading variability, to ensure physical testing is performed at worst case:

assembly loads were applied, predicting assembly residual stress, verified by strain gauging, and a range of service loads were superimposed.

The predicted worst-case stress conditions were analysed against three ‘constant life’ limits [Gerber, 1874, Goodman 1899, Soderberg 1930], a common aerospace approach, giving predicted safety factors. Finally, equivalent fatigue tests were conducted on ten prototype implants.

Taking a worst-case size (thinnest-walled 48 mm inner/58 mm outer), under assembly loading the peak tensile stress in the titanium shell was 274 MPa (Fig. 2). With 5kN superimposed jogging loading, at an extreme 75° inclination, 29 MPa additional tensile stress was predicted. This gave mean fatigue stress of 288.5 MPa and stress amplitude of 14.5 MPa (R=0.9). Against the most conservative infinite life limit (Soderberg), the predicted safety factor was 2.40 for machined material, and 2.03 for forged material, or if a stress-concentrating surface scratch occurs during manufacturing or implantation (Fig. 3). All cups survived 10,000,000 fatigue cycles.

This study employed computational modelling and physical testing to verify the strength of a joint prosthesis concept, under worst case static and fatigue loading conditions. The analysis technique represents an improvement in the state of the art where testing standards refer to conventional prostheses; similar methods could be applied to a wide range of novel prosthesis designs.


Mark Kester Jerry D'Alessio Cesar Flores-Hernandez Darryl D Lima

Introduction

Component and limb alignment (especially varus >3°) have been associated with soft-tissue imbalance, increased polyethylene wear, and tibial tray subsidence. However, not all clinical outcome studies have found significant correlation between tibial varus and revision surgery. While the link between limb alignment and failure has been attributed to increased medial compartmental loading and generation of shear stress, quantitative biomechanical evidence to directly support this mechanism is incomplete. In this study, we analyzed the effect of limb alignment and tibial tray alignment on the risk for bone damage and subsequent risk for tray loosening.

Methods

A finite element model of knee arthroplasty previously validated with in vitro cadaver testing was used. Models of four subjects were constructed with tibial resections simulating a 0°, 3°, 5°, and 7° varus alignment with respect to the mechanical axis of the tibia and the tray implanted at the corresponding angles. Tibial tray orientation was simulated without change in limb alignment (i.e. maintaining the mechanical axis of the knee at 0°) and with limb alignment ranging from 3° valgus to 7° varus (Fig 1).

A static load equivalent to three times the bodyweight of the subject was applied in line with the mechanical knee axis. Relative motion between the tibial tray and tibial bone was calculated. Elements with an equivalent von Mises strain >0.4% were selected and assigned an elastic modulus of 5 MPa to reflect damaged bone. Simulation was repeated and after-damage micromotion recorded.


Nick Dong Jim Nevelos Stefan Kreuzer

Combined anteversion angle of acetabular component and femeral neck is an important factor for total hip arthroplasty (THA) as it may affect impingement and dislocation. Previous studies have collected data mainly from direct measurements of bone morphology or manual measurements from 2D or 3D radiolographic images. The purpose of this study was to electronically measure the version angles in native acetabulum and femur in matured normal Caucasion population using a novel virtual bone database and analysis environment named SOMA™.

221 CT scans from a skeletally mature, normal Caucasian population with an age range of 30–95 years old. The population included 135 males and 86 females. CT data was converted to virtual bones with cortical and cancellous boundaries using custom CT analytical sofware. (SOMA™ V.3.2) Auxillary reference frames were constructed and measurements were performed within the SOMA™ design environment. Acetabular Anteversion (AA) angle as defined by Murray1 was measured. The acetabular rim plane was constructed by selecting 3 bony land marks from pubis, ilium and ischium. A vector through acetabular center point and normal to the rim plane defined the plane for the AA measurement. The AA was defined as the angle of this plane relative to the frontal (Coronal) plane of the pelvis. The Femoral Neck Anteversion (FNA) angle was measured from the neck axis plane to the frontal (Coronal) plane as defined by the posterior condyles. The neck axis plane was constructed to pass through femoral neck axis perpendicular to the transverse plane. The combined anteversion angle was computed as the summation of acetabular and femoral anteversion angles. Student's t tests were performed to compare gender difference with an assumed 95% confidence level.

The mean AA angle for total population was 25.8°, SD=7.95°. The mean AA for male was 24.8°, SD=5.93° and for female was 27.3°, SD=7.14°. P=0.009.

The mean FNA angle for total population was 14.3°, SD=6.52°. The mean FNA for male was 13.5°, SD=7.97° and for female was 15.5°, SD=7.80°. P=0.058.

The mean combined anteversion angle for total population was 40.1°, SD=10.76°. The mean combined anteversion angle for male was 38.3° SD=10.39 ° and for female was 42.8° SD=10.83 °. P=.0002. The plot of AA as a function of FNA shows weak correlation for both male and female. (Figure 1) The frequency distribution is shown in Figure 2.

The results showed the both AA, FNA and combined anteversion angles were significantly smaller in male population than that in female population. The FNA angle of the cementless femoral stem can be smaller than with the natural femur, therefore a higher AA or higher posterior build up may be required for the acetabular component for optimal function of a THA.


Hiroshi Egawa Tomoya Takasago Tomohiro Goto Natsuo Yasui

Introduction

Hip Arthrodesis had been considered as a useful surgical option in young adult patient with high activity demands suffering from osteoarthritis of the hip. Although the procedure surely eliminates pain of the hip joint, it can also cause disorders of the adjacent joints in addition to the complete loss of motion, might consequently deteriorate the activity of daily living. The purpose of this retrospective study was to investigate the efficacy and drawback of hip arthrodesis, focusing on the effect of this procedure on the adjacent joints.

Materials and Methods

From 1976 to 1989, 29 hip arthrodesis were performed and 22 hips were followed up (1 died, 6 lost). Disorders led to arthrodesis were septic arthritis (1 hip), post-traumatic (1), osteonecrosis (1), primary osteoarthritis (3), and secondary osteoarthritis due to DDH (16). The average age at surgery was 38 years (range, 19–53 years, 6 men and 16 women). Hip arthrodesis was indicated for young active adults with end stage osteoarthritis, who had normal or mild osteoarthritis in contralateral hip and needed physical labor. The hip was positioned in 30 degrees of flexion, 0 to 5 degree of external rotation, and 0 to 5 degree of abduction. Clinical and radiographic assessment was done for these patients. The clinical follow-up consisted of questionnaire which assessed ability of typical Japanese daily living movement and patient's satisfaction. The condition of the adjacent joints was evaluated clinically and radiographically.


Christina Esposito Anne Roques Michael Tuke William K Walsh William L Walter

Introduction

Two types of ceramic materials currently used in total hip replacements are third generation hot isostatic pressed (HIPed) alumina ceramic (commercially known as BIOLOX®forte, CeramTec) and fourth generation alumina matrix composite ceramic consisting of 75% alumina, 24% zirconia, and 1% mixed oxides (BIOLOX®delta, CeramTec). Delta ceramic hip components are being used worldwide, but very few studies have analyzed retrieved delta bearings. The aim of this study is to compare edge loading ‘stripe’ wear on retrieved femoral heads from delta-on-delta, delta-on-forte and forte-on-forte ceramic bearings revised within 2 years in vivo.

Material and Methods

Ceramic bearings revised at one center from 1998 to 2010 were collected (61 bearings). Eleven delta heads revised between 1–33 months were compared to 24 forte femoral heads with less than 24 months in vivo (Figure 1). The surface topography of the femoral heads was measured using a RedLux AHP (Artificial Hip Profiler, RedLux Ltd, Southampton, UK). Three representative samples were examined with a FEI Quanta 200 Scanning Electron Microscope (SEM).


Peter Bonutti Aaron Essner Lizeth Herrera Jason Longaray Mark Kester

It is difficult for surgeons to make the decision on which design or material to use given multiple available options for total knee arthroplasty. Due to the complex interaction of soft tissue, implant position, patient anatomy, and kinematic demands of the patient, the prosthetic design of a knee device has traditionally been more important than materials. The purpose of this study was to examine the overall influence of both implant design and materials on volumetric wear rates in an in vitro knee simulator study for two knee designs.

Two different designs (single radius and J-curve) with two highly crosslinked materials (Sequentially crosslinked and annealed PE (X3®, Stryker Orthopaedics, Mahwah, NJ) (7.5 kGy moderately crosslinked UHMWPE (XLPE, Smith and Nephew, Memphis, TN)) were evaluated. The two designs tested were the Triathlon® CR knee system (single radius design)(Stryker Orthopaedics, Mahwah, NJ) and the Legion™ Oxinium® CR knee system (J-curve design) (Verilast™, Smith and Nephew, Memphis, TN). Three inserts per condition were tested in this study. This comparison incorporates the effects of both materials and designs: different femoral component materials, different tibial bearing materials, and implant geometry (J-curve vs. single radius saggital profile). All devices were tested under ISO 14243-3 normal walking using an MTS knee simulator for a total of 5 million cycles. Standard test protocols were used for cleaning, weighing and assessing the wear loss of the tibial inserts (ASTM F2025). Soak control specimens were used to correct for fluid absorption with weight loss data converted to volumetric data (by material density). Statistical analysis was performed using the Student's t-test.

Total volume loss results are shown in Figure 1. Test results show a 36% reduction (p<0.05) in volume loss and a 30% reduction (p<0.05) in wear rate for the single radius design compared to the J-curve design, respectively. All comparisons are statistically significant by the t-test method (p<0.05). Visual examination of all worn inserts revealed typical wear scars and features on the condylar surfaces, including burnishing.

Results indicate superior wear resistance for the single radius system. This finding indicates that a combination of implant design and prosthesis material plays a significant role in knee wear rates. The in vitro low volumetric wear observed in the single-radius prosthesis could theoretically influence long term survivorship in vivo, and supports the potential for improved durability and long term wear performance for this design when compared to a J-curved femoral component. Longer term clinical evidence such as published studies or outcomes reported in the available joint registries will be needed to establish whether any material or design can achieve a 30-year or longer outcome.


Joseph Fetto

Recent trends in surgical techniques for THR, i.e. MIS and anterior approaches, have spawned an interest in and possible need for shorter femoral prostheses. Although, early clinical investigations with custom short stems have reported very encouraging results, the transition to off-the-shelf (OTS) versions of shorter length prostheses has not met with the same degree of success. Early reports with OTS devices have documented unacceptably high and significant incidences of implant instability, migration, mechanical/aseptic failure, and technical difficulty in achieving reproducible implantation outcomes. They have highlighted the absolute need for a better understanding of the consequences of changes in implant design as well as for improvements in instrumentation and surgeon training.

Two basic questions must be addressed. First, what is the purpose of a stem? And second, can stem length be reduced and if so by how much can this be safely done. What are the effects of stem shortening and are there other design criteria which must take on greater importance in the absence of a stem to protect against implant failure.

To examine these questions a testing rig was constructed which attempts to simulate the in vivo loading situation of a hip, fig. 1. Fresh cadaveric femora were tested with the femora intact and then with femoral components of varying stem length implanted to examine the distribution of stresses within the femur under increasing loads as a function of stem length.

Our studies indicated that a stem is not an absolute requirement in order to achieve a well functioning, stable implant. However in order to reduce the possibility of mechanical failure a reduced stem or stemless implant absolutely must have three important characteristics to its design. First, it must have sufficient medial/lateral dimension to provide stability against subsidence and varus stress; second it must have a flat posterior surface, parallel and in contact with the posterior endosteal surface of the proximal femur with which to maximize A/P stability against flexion/extension forces (As a consequence of this design feature, appropriate anteversion must be achieved in the neck region of the prosthesis and not by rotation of the implant within the proximal metaphyseal cavity of the femur); and third, the implant must also have a cross-sectional geometry that will stabilize against torsional loading about the long axis of the femur.

Therefore, simply reducing the length of an existing implant to accommodate changes in surgical techniques may not be a reasonable or safe design change. Such shortened versions of existing stem designs must be rigorously tested before being released for general use. The required design parameters outlined above have been clinically validated in custom fabricated implants. They have been shown to reduce aseptic loosening and migration of a short stem femoral implant. This report will provide the clinical review of a multi-center experience with the first 200 off-the-shelf “Lateral Flare” short stem implants.


Masataka Fujii Nobuhiro Abe Takayuki Furumatsu Shinichi Miyazawa Yukimasa Okada Toshifumi Ozaki

Purpose

Computer navigation system has been reported as a useful tool to obtain the proper alignment of lower leg and precise implantation in TKA. This system alsoãζζhas shown the accurate gap balancing which was lead to implants longevity and optimal knee function. The aim of this study was determine that the postoperative acquired deep knee flexion would be influenced by intraoperative kinematics on navigated TKA even under anesthesia.

Materials & methods

Forty knees from 40 patients, who underwent primary TKA (P.F.C. sigma RPF, DePuy Orhopaedic International, Leed, UK) with computer-navigation system (Ci Knee, BrainLAB / DePuy Inc, Leeds, UK), were recruited in this study. These patients were classified into two groups according to the recorded value of maximum knee flexion at three month after surgery: 15 patients who obtained more than 130 degrees of flexion in Group A, and 25 patients less than 130 degrees in Group B. We retrospectively reviewed about intraoperative kinematics in each group, to obtain the clue for post operative deep-flexion. The measurements of intraoperative kinematics were consisted of 3 points: femoral rotation angle (degree) and antero-posterior translation (mm), which were measured as the translation of the lowest points of femoral component to tibial cutting surface, and the joint gap difference between the medial and lateral components gap (mm). All joint kinematic data were recorded at every 10 degrees of flexion from maximum extension to flexion under anesthesia.


Takaaki Fujishiro Takayuki Nishiyama Shinya Hayashi Noriyuki Kanzaki Shingo Hashimoto Nao Shibanuma Masahiro Kurosaka

Background

The cementless acetabular component fixed with several screws is one of the most widely used approaches in THA. These screws rely on contact pressure and the resultant friction between the screw head and the cup to control translation and angulation of the prosthesis. However, intraoperative change of the acetabular component alignment during screw fixation should be hardly detected. Acetabular component alignment can be assessed using computer-assisted navigation systems with realtime adjustments for component position. The purpose of the current study was to evaluate intraoperative change of acetabular component alignment during screw fixation using navigation system.

Patients and Methods

Primary THAs were performed in 74 hips using CT based fluoroscopic matching navigation system (VectorVision, BrainLAB). The patients were 18 men and 56 women with a mean age of 64.4 years (range, 47–78 years) at operation. Intraoperative acetabular component inclination and anteversion were measured at the time of press-fit, and after screw fixation using the cup verification function in the system. Mean of the absolute difference between at the time of press-fit and after screw fixation was evaluated as intraoperative change of acetabular component. We measured the distance from the center of the femoral head to the inter-teardrop line as a horizontal and vertical reference on the postoperative radiograph. The number of screws was also investigated.


Kenji Fujita Tamon Kabata Toru Maeda Yoshitomo Kajino Shintaro Iwai Kazunari Kuroda Hiroyuki Tsuchiya

Introduction

The aim of this study was to assess the accuracy of aligning the cup with the transverse acetabular ligament (TAL) in total hip arthroplasty (THA) and the reproducibility of this procedure by using computer-assisted navigation.

Methods

Between January 2011 and March 2012, 75 patients (81 hips) underwent primary THA using the posterolateral approach at our hospital. We excluded 4 hips with a history of pelvic osteotomy; thus, the study included 77 hips. We measured the anatomical anteversion of the TAL intraoperatively by aligning the inferomedial rim of the cup trial with the TAL using computer-assisted navigation. We set the abduction to 45° at measure of the anteversion of the TAL. Measurements for each hip were independently performed thrice by 2 surgeons chosen among 1 expert and 6 non-experts. The surgeon performing the measurement was blinded during this process; the navigation screen was turned away from the surgeon's field of view. Anatomical inclination and anteversion were measured with reference to the functional pelvic plane. The intraclass correlation coefficient (ICC) was used to assess intra- and inter-observer reliability. The mean value of all 6 measurements was used to determine the anteversion of the TAL in each hip.


Yoshinari Fujita Yusuke Fukuhara Kenta Saito Kenichiro Matsuzaki Masaaki Takahashi Akio Yokoi

Introduction

Venous thromboembolism (VTE) is one of the common complications after total hip replacements (THRs). To reduce the risk of VTE, early rising, active movement of the foot, the use of a foot pump or graduated compression stockings and prophylactic administration of anticoagulant drugs are important. Further, intraoperative factors should be taken intoãζζconsideration.

Objective

The objective of this study is to assess the influence of surgical approaches, which are a modified Watson-Jones approach and a posterolateral approach, on the frequency of VTE after primary THRs.


Kazuo Fujiwara Hirosuke Endou Yoshiki Okada Shigeru Mitani Toshifumi Ozaki

Objectives

The anteversion angle of the cup is important for achieving the stability and avoiding the dislocation after total hip arthroplasty (THA). We place the component considering with the change of inclination of pelvis with its posture change. We analyzed the perioperative pelvic inclination angles with posture change and the time course.

Materials and Methods

We treated 40 hips in 40 patients (9 males and 31 females) with cementless THA that were performed from January 2007 to December 2008 in our hospital. 30 osteoarthritis hips, 3 rheumatoid arthritis hips and 7 idiopathic osteonecrosis hips were included. All patients were performed THA with VectorVision Hip 2.5.1 navigation system (BrainLAB, Feldkirchen, Germany). We used AMS HA cups and PerFix stems (KYOCERA Medical co., Osaka, Japan). The mean age of surgery was 59 years old (35–79 years old). The pelvic inclination angles (PIA) were measured with anteroposterior radiographic image in accordance with the Doiguchi's method.


Atsushi Funayama Masashi Okubo Hidenori Shimizu Shunichi Kawasakiya Atsushiro Fujie Yoshiaki Toyama

Introduction

The goal of total hip arthroplasty (THA) should be to reconstruct the acetabulum by positioning the hip center as close as possible to the anatomical hip center. However, the true position of the anatomic hip center can be difficult to determine during surgery on an individual basis. In 2005, we designed, produced an acetabular reaming guide, and clinically used to enable cup placement in the ideal anatomical position. This study was examined the accuracy the reaming guide for THA in prospective study.

Methods

This guide was applied consecutive 230 patients in primary THA. During planning, the distance from the acetabular edge to the reaming center and from the center to the perpendicular of the inter-teardrop line was measured on an anteroposterior (AP) X-ray. The reaming guide was adjusted depend on the reaming center by based planning. Acetabular reaming was performed with the process reamer.


Rajnish Garg Mohammad Yamin Pankaj Mahindra Sudhanshu Nandra

Today minimally invasive surgery inspires orthopaedic surgeons to consider techniques that minimize morbidity and produce equal or better outcomes. Minimally invasive surgery–total knee arthroplasty (MIS-TKA) approach involves a medial para-patellar incision which leads to a smaller skin incision, limited soft tissue dissection and sparing of the Quadriceps muscle.

This prospective and retrospective study was carried out at Dayanand Medical College and Hospital, Ludhiana (India) from January 2007 to June 2010 to evaluate forty nine patients with unilateral and six patients of Bilateral MIS-TKA. Patients with osteoarthritis and rheumatoid arthritis undergoing primary TKA using cemented modular posteriorly stabilized prosthesis were included in the study. All the procedures were performed through anterior midline incision measuring 8.5–10 cms (mean 9.2 cms). Extent of the incision into the quadriceps tendon was limited to the level of superior pole of patella and vastus medialis muscle was not split. Patella was not everted but retracted laterally. Four in One Nexgen legacy, minimal invasive surgery instrumentation was used. Aggressive physiotherapy was started on the first postoperative day with knee bending and walking on day two. The patients were evaluated according to knee society knee score and function score at one, three and six months and again at one year postoperatively.

Mean final knee score improved from 30 to 91 (p-value = .00001). Mean functional score improved from 25 to 78 (p-value = .00001). Mean stability score improved from 19.46 to 22.98 points postoperatively. Patients with lesser preoperative flexion contracture had better outcomes and preoperative range of motion predicted final range of motion. Mean ROM improved from preoperative value of 85 to 101 at discharge, 114 at 12 weeks and 120 at 6 months (p-value = .0007, .0006, .0009 respectively). 79.1% patients were completely pain-free on the final follow-up. Mean tourniquet time was 65 minutes (55–75). 91.4% patients suffered <300 ml blood loss in drains. One patient each of patellar maltracking and deep infection was seen in our study.

We concluded that MIS-TKA with quadriceps sparing approach in our patients lead to a limited arthrotomy, decreased blood loss, less blood transfusion requirements, less postoperative pain, faster recovery of motion and return of function. This study proposes that MIS-TKR has many advantages over the conventional procedure and these are mainly attributed to the sparing of quadriceps muscle.


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Giorgio Gasparini Pasquale Guzzi Teresa Pugliese Olimpio Galasso

The removal of cement debris at the time of primary and revision joint replacement has been facilitated through the introduction of coloured bone cements. Up to date, few studies have evaluated the effect of methilene blue dye on physical, mechanical and pharmacological properties of cements. In this light, we evaluated the effects of adding methylene blue to bone cement with or without antibiotics (gentamicin, vancomycin or both). The addition of methylene blue to plain cement significantly decreased its mean compression (95.4±3 MPa vs 100.1±6 MPa, p = 0.03) and bending (65.2±5 MPa vs 76.6±4 MPa, p < 0.001) strengths, mean setting time (570±4 seconds vs 775±11 seconds, p = 0.01), as well as its mean elastic modulus (2744±97 MPa vs 3281±110 MPa, p < 0.001). Bending resistance decreases after the supplementation of the coloured cement with vancomycin and gentamicin (55.7±4 MPa vs 65.2±5 MPa, p < 0.001). The release of antibiotics from the bone cement was significantly decreased by the methylene blue. Indeed, the release of gentamicin alone was 385.5±26 μg in comparison to 228.2±24 μg when the methylene blue was added (p < 0.001), while the release of gentamicin in combination with vancomycin was 613±25 μg vs 498.5±70 μg (p = 0.018) when the dye was added to the same formulation. With this study we demonstrated several theoretical disadvantages of the antibiotic-loaded bone cement coloured with methylene blue, although caution should be exercised in transferring our findings to the clinical context. Based on our findings, we do not recommend methylene blue supplementation of PMMA for routine clinical use.


Sabyasachi Ghosh Satya Prasad Biswas Usman Amjid

INTRODUCTION

Uncemented total hip replacement is on the rise worldwide. Latest studies from various European and other developed country joint registers are clearly showing that it is taking preference over the cemented joint replacements. These figures were discussed most recently at the London hip meeting. Our study is related to one single make of implant the Exceed hip (Biomet) at two hospitals in Northamptonshire, Kettering UK.

MATERIAL & METHODS

Our series includes 256 cases of Exceed uncemented total hip replacement done in 236 patients with a minimum follow up of 6 months and maximum of 5 years. The study included 126 female and 110 male patients. Out of this number 121 cases were done at Kettering General Hospital and 135 cases were performed at Woodlands Hospital private limited in Kettering. The cases were performed by 2 senior consultants and one junior consultant. The total number of cases was 317 but 73 cases were lost to follow up and 2 patients had expired at the time of the study. In all cases pre operative and post operative Harris hip scores were measured. Patients were asked to fill up the scores in retrospect through post. The range of motion parameter and range of motion scale were measured and added from clinical notes. The average age of patients in our study was 71.2 years with the oldest patient being 90 years old and the youngest being 34 years old. Most common cause for replacement was primary osteoarthritis in 202 cases. In 52 cases it was done for secondary osteoarthritis due to rheumatoid arthritis or post traumatic osteoarthritis following dislocation and acetabular fractures. In 2 cases it was done for fracture neck of femur. All the cases were done through posterior approach. One senior surgeon used bone grafts in the acetabular floor harvested from the femoral head at time of surgery in all of his cases. The ABT ringloc shell, polyethylene liner was used in all cases.

The average pre operative Harris hip score was 43.15 and average post operative Harris hip score was 78.32. In 4 cases peri prosthetic fractures occurred per operatively and needed fixation. In 3 cases dislocation occurred but only one case needed revision due to recurrent dislocation.


Tomohiro Goto Yasuaki Tamaki Daisuke Hamada Tomoya Takasago Hiroshi Egawa Natsuo Yasui

Introduction

Herniation pits had been considered as a normal variant, a cystic lesion formed by synovial invagination. On the contrary, it was also suggested that herniation pits were one of the diagnostic findings in femoroacetabular impingement (FAI) because of the high prevalence of herniation pits in the FAI patients. To date, the exact etiology is still unknown. The purpose of this study was to evaluate whether there is an association between the presence of herniation pits and morphological indicators of FAI based on computed tomography (CT) examination.

Materials and methods

We reviewed the CT scans of 245 consecutive subjects (490 hips, age: 21–89 years) who had undergone abdominal and pelvic CT for reasons unrelated to hip symptom from September, 2010 to June, 2011. These subjects were mainly examined for abdominal disorders. We confirmed by the questionnaire survey that there were no subjects who had symptoms of hip joints. We reviewed them for the presence of herniation pits and the morphological abnormalities of the femoral head and acetabulum. Herniation pits were diagnosed when they were located at the anterosuperior femoral head-neck junction with a diameter of more than 3 mm. We measured following four signs as indicators for FAI: α angle, center edge angle (CE angle), acetabular index (AI), and acetabular version. Mann-Whitney U-test was used for statistical analysis.


Arthur Grzesiak Brigitte Jolles Antoine Eudier Hooman Dejnabadi Caroline Voracek Claude Pichonnaz Kamiar Aminian Estelle Martin

INTRODUCTION

Mobile-bearing knee prostheses have been designed in order to provide less constrained knee kinematics compared to fixed-bearing prosthesis. Currently, there is no evidence to confirm the superiority of either of the two implants with regard to walking performances. It has been shown that subjective outcome scores correlate poorly with real walking performance and it has been recommended to obtain an additional assessment of walking ability with objective gait analysis.

OBJECTIVES

We assessed recovery after total knee arthroplasty (TKA) with mobile- and fixed-bearing between patients during the first postoperative year, and at 5 years follow-up, using a new objective method to measure gait parameters in real life conditions.


Rajesh Ghosh Kaushik Mukherjee Sanjay Gupta

Despite the generally inferior clinical performance of acetabular prostheses as compared to the femoral implants, the causes of acetabular component loosening and the extent to which mechanical factors play a role in the failure mechanism are not clearly understood yet. The study was aimed at investigating the load transfer and bone remodelling around the uncemented acetabular prosthesis.

The 3-D FE model of a natural right hemi-pelvis was developed using CT-scan data. The same bone was implanted with two uncemented hemispherical acetabular components, one metallic (CoCrMo alloy) and the other ceramic (Biolox delta), with 54 mm outer diameter and 48 mm bearing diameter. The FE models of the implanted pelvis (containing ∼116000 quadratic tetrahedrals) were generated using a submodelling approach, which were based on an overall full model of implanted pelvis (containing ∼217600 quadratic tetrahedrals) acted upon by hip joint force and twenty one muscle forces. The apparent density (ρ in g cm−3) of each cancellous bone element was calculated using linear calibration of CT numbers of bone, from which the Young's modulus (E in MPa) was determined using the relationship, E = 2017.3 ρ2.46 [1]. Implant-bone interface conditions, fully bonded and debonded with friction coefficient μ = 0.5, were simulated using contact elements. Applied loading conditions consist of two load cases during a gait cycle, corresponding to 13% and 52% of the walking cycle. Fixed constraints were prescribed at the pubis and at the sacroiliac joint. The bone remodelling algorithm was based on strain energy based site-specific formulation [2]. The FE analysis, in combination with the bone remodelling simulation, was performed using ANSYS FE software.

The predicted changes in peri-prosthetic bone density were similar for the metallic and the ceramic implant. For debonded implant-bone interface, stress shielding led to ∼20% reductions in bone density at supero-anterior, infero-anterior and posterior part of the acetabulum (Fig. 1). However, bone apposition was observed at the supero-posterior part of the acetabulum, where implantation led to ∼60% increase in bone density (Fig. 1). The effect of bone resorption was higher for the fully bonded implant-bone interface, wherein bone density reductions of 20–50% were observed in the cancellous bone underlying the implant (Fig. 1), which is indicative of implant loosening over time. However, implantation led to an increase in bone density around the acetabular rim for both the interface conditions (Fig. 1). These results are well corroborated by the earlier studies [3, 4]. Implantation with a ceramic component resulted in 2–7% increase in bone density at supero-posterior part of the acetabulum as compared to the metallic component, for the debonded interface condition. Considering better wear resistant properties and absence of metal ion release, results of this study suggest that the ceramic component might be a viable alternative to the metallic prosthesis.


Kaushik Mukherjee Bidyut Pal Sanjay Gupta

The effects of metal ion release and wear particle debris in metal-on-metal articulation warrants an investigation of alternative material, like ceramics, as a low-wear bearing couple [1]. Short-stem resurfacing femoral implant, with a stem-tip located at the centre of the femoral head, appears to provide a better physiological load transfer within the femoral head and therefore seems to be a promising alternative to the long-stem design [2]. The objective of this study was to investigate the effect of evolutionary bone adaptation on load transfer and interfacial failure in cemented metalli