Introduction

In Total Knee Arthroplasty (TKA) a proper choice of the implant size is mandatory in order to guarantee the success of the prosthesis, although the tribological behavior TKA is strongly influenced by the implant design.

Retrieval analysis of failed total knee prosthesis is essential to investigate the wear mechanism leading to osteolysis and loosening of the implant. Assessments from retrieval studies constitute crucial information in the effort to improve prosthesis functionality and reduce the risk of revision. The aim of the present study was to investigate the correlation among different implant sizes of retrieved TKA and patients' variables such as Body Mass Index (BMI) in terms of surface modifications and morphology change, in order to examine prosthesis properties and performances. In particular, this study can improve the understanding of the tribological behavior of total knee prosthesis and it can help the surgeon to select the best implant size of TKA considering patient's variables.

Methods

Twelve retrieved total knee prostheses of the same design but with different sizes were investigated. These prostheses were all cemented, fixed and posterior stabilized. These prostheses were explanted from 12 patients after a mean of 3.2 years (from 1.1 to 7.4 years). These patients had undergone a primary TKA at our hospital between 2005 and 2010; there were 10 women and 2 men with a mean age of 68 years (ranging from 48 to 77 years) at implantation. A qualitative assessment of wear patterns and surface damages was performed on femoral components and polyethylene inserts. Roughness analyses were obtained on femoral components to assess surface modifications. Surface roughness of the metallic femoral components was performed with a contact rugosimeter. Following an internal protocol, thirty measurements were acquired from each condyle. Two roughness parameters were take into account: Ra (the Mean Roughness, i.e. the arithmetical mean value of the deviations of the roughness profile about the centre line) and Rsk. (i.e. the skewness, indicates the prevalence of peaks or valleys and quantifies the asymmetry of the profile variation from the mean line). Prostheses time in-vivo and patient details were known.

Background

In 2012, the National Joint Registry recorded 86,488 primary total hip replacements (THR) and 9,678 revisions (1). To date aseptic loosening remains the most common cause of revision in hip and knee arthroplasty, accounting for 40% and 32% of all cases respectively and emphasising the need to optimise osseointegration in order to reduce revisions. Clinically, osseointegration results in asymptomatic stable durable fixation of orthopaedic implants. Osseointegration is a complex process involving a number of distinct mechanisms affected by the implant surface topography, which is defined by surface orientation and surface roughness. Micro- and nano-topography levels have discrete effects on implant osseointegration and yet the role on cell function and subsequent bone implant function is unknown. Nanotopography such as collagen banding is a critical component influencing the SSC niche in vivo and has been shown to influence a range of cell behaviours in vitro (2,3). We have used unique fabricated nanotopographical pillar substrates to examine the function of human bone stem cells on titanium surfaces.

Aim

To investigate the effect of nanotopographical cues on adult skeletal stem cell (SSC) fate, phenotype and function within in-vitro environments.

Introduction

Metals used for total knee arthroplasty (TKA) are well known for their good biocompatibility, but may be a source of a release of metal ions that can be a cause of local and systemic adverse effects, aseptic loosening, and hypersensitivity reactions. One of the major difficulties in performing TKA is the selection of implants for patients who are preoperatively diagnosed as subject to metal sensitivity. Alternative solutions in cases of hypersensitivity are implants without metal constituents or metallic implants treated with a non-sensitive surface process. The aim of this study was to evaluate clinical results in patients who had been preoperatively diagnosed with metal sensitivity and who subsequently were provided with the zirconia-ceramic LFA-III TKA, and with a minimum 5-year follow-up.

Methods

Five patients (8 knees) with metal sensitivity underwent TKA using cemented zirconia-ceramic LFA-III implants. The LFA-III implant (KYOCERA Medical Co., Japan) is composed of a zirconia ceramic femoral component and a titanium-alloy tibial component with a polyethylene insert. All patients were female andthe average age at the time of surgery was 76.1 years. The average follow-up time was 7.2 years. Clinical and radiographic assessments were conducted with the Knee Society scoring system.

Objective

We performed total knee arthroplasty (TKA) without patella resurfacing in patients with osteoarthritis (OA) of the knee.

The purpose of the present study was to evaluate the clinical results and the appropriateness TKA without patella resurfacing.

Methods

A total of 61 patients (61 affected knees) who had undergone a Low Contact Stress mobile − bearing knee arthroplasty (LCS− TKA) (Depuy, Warsaw, IN. USA) 10 years or more before the present study were enrolled. The LCS− TKAs did not include patella resurfacing. The patients' mean age was 77.7 ± 6.1 years (range: 59−94 years). The mean follow-up period was 121 ± 2.4 months (range: 120−129 months). The clinical evaluation used the scoring system for OA of the knees issued by the Japanese Orthopaedic Association (JOA score). We defined patellofemoral (PF) pain, crepitation, patellar clunk syndrome, spin-out, and reoperation as complications. We also used X-Ray imaging to measure the component angle, patella height, lateral shift ratio, tilting angle, femorotibial angle, posterior condylar offset and joint line, and evaluated the localization of sclerotic changes in the patella.

All of the LCS− TKAs were performed by one surgeon using the midvastus approach. During the operation, the osteophyte around the patella was resected, and the osteophyte on the articular surface was shaped using a bone saw.

For statistical analysis we performed Mann-Whitney's U test and adopted a significance level of P<5%.

Introduction

Modular stems are commonly used to improve fixation in revision total knee arthroplasty (TKA). Hybrid fixation, in which cement is placed around the metaphysical portion of the component combined with an uncemented diaphyseal modular stem, has potential advantages including ease of insertion, improved component alignment, and ease of removal if needed. The aim of this study was to evaluate clinical results of revision total knee arthroplasty with uncemented modular stems using a hybrid fixation technique with a minimum 5-year follow-up.

Methods

23 revision TKAs were performed in 21 patients with hybrid fixation using uncemented modular stems. 3 patients (3 knees) had died of causes unrelated to the index arthroplasty at the time of the study, and 1 patient (1 knee) was lost to the follow-up. The remaining 19 knees were clinically and radiographically evaluated for the present study. The average follow-up time was 9.5 years. The average age of the patients was 70.5 years at the time of the revision surgery. The average time between the primary and revision surgeries was 10.6 years.

Introduction

Patient specific instrumentation (PSI) generates customized guides from an MRI- or CT-based preoperative plan for use in total knee arthroplasty (TKA). PSI software executes the preoperative planning process. Several manufacturers have developed proprietary PSI software for preoperative planning. It is possible that each proprietary software has a unique preoperative planning process, which may lead to variation in preoperative plans among manufactures and thus variation in the overall PSI technology. The purpose of this study was to determine whether different PSI software generate similar preoperative plans when applied to a single implant system and given identical MR images.

Methods

In this prospective comparative study, we evaluated PSI preoperative plans generated by Materialise software and Zimmer Patient Specific Instruments software for 37 consecutive knees. All plans utilized the Zimmer Persona™ CR implant system and were approved by a single experienced surgeon blinded to the other software-generated preoperative plan. For each knee, the MRI reconstructions for both software programs were evaluated to qualitatively determine differences in bony landmark identification. The software-generated preoperative plans were assessed to determine differences in preoperative alignment, component sizes, and resection depth. PSI planned bone resection was compared to actual bone resection to assess the accuracy of intraoperative execution.

Introduction

Traditionally an inpatient hospital stay has been required for all joint replacement surgery. The three primary drivers of cost for joint replacement have been implant cost, other hospital charges and postoperative rehabilitation costs. The three primary reasons that have made hospitalization necessary are pain control, therapy and possible transfusion. Advances in surgical technique, implants, comprehensive blood management, and multimodal pain management have allowed a marked reduction in the hospital stay required, eliminated the need for extensive formal rehabilitation. The purpose of this study is to evaluate if hip resurfacing can be performed safely and cost-effectively as an outpatient procedure.

Methods

We present the short-term outcome of our first 77 hip resurfacings done as an outpatient procedure performed by two experienced surgeons. Young patients without major medical co-morbidities were selected. The average age was 53±6 years old (range: 38 to 66), there were 57 men and 20 women. The mean ASA score was 1.6±0.5 (range 1 to 2). The diagnosis was OA in 56, dysplasia in 17, avascular necrosis in 2, and others in 2.

Introduction

A recent report based on the NARA database (Nordic Arthroplasty Register Association) found that the 10-year survivorship of patients under 50 with traditional total hip arthroplasty was only 83% in 14,600 cases. The purpose of this study was to compare our experience using metal-on-metal hip resurfacing arthroplasty (HRA) to treat these patients.

Methods

from May 2001 to Feb 2012, a single surgeon performed 1029 metal-on-metal HRA in 855 patients younger than 50 years old. Three different implants were used in consecutive groups of patients, first the Corin hybrid HRA (182); then the Biomet hybrid HRA (306); and finally the Biomet uncemented HRA (541). The primary diagnoses were OA (707); dysplasia (125); osteonecrosis (98); post-trauma (28); Legg-Calve-Perthes (27) and others (44). The average age was 43±6 years; 74% were men; the average BMI was 27±4; mean femoral component size was 50±4 (range 40–62); the average T-score was 0±1. 37% of our patients reported a UCLA Activity level of 9 or 10 (impact sports). Six died with causes unrelated to their HRAs. The rate of follow-up was 94%. Our patients were not selected by any criteria except the surgeon's technical ability to perform an HRA.

Background

Radiostereometric Analysis (RSA) is an accurate measure of implant migration following total joint replacement surgery. Early implant migration predicts later loosening and implant failure, with RSA a proven short-term predictor of long-term survivorship. The proximal migration of an acetabular cup has been demonstrated to be a surrogate measure of component loosening and the associated risk of revision. RSA was used to assess migration of the R3 acetabular component which utilises an enhanced porous ingrowth surface. Migration of the R3 acetabular component was also assessed when comparing the fixation technique of the femoral stems implanted.

Methods

Twenty patients undergoing primary total hip arthroplasty were implanted with the R3 acetabular cup. The median age was 70 years (range, 53–87 years). During surgery tantalum markers were inserted into the acetabulum and the outer rim of the polyliner. RSA examinations were performed postoperatively at 4 to 5 days, 6, 12 and 24 months. Data was analysed for fourteen patients to determine the migration of the acetabular cup relative to the acetabulum. Of these fourteen patients, six were implanted with a cementless femoral stem and eight with a cemented femoral stem. Patients were clinically assessed using the Harris Hip Score (HHS) and Hip Disability and Osteoarthritis Outcome Score (HOOS) preoperatively and at 6, 12 and 24 months postoperatively.

Background

Safety and efficacy of novel prostheses relies on the determination of early implant migration and subsequent risk of loosening. Radiostereometric Analysis (RSA) has been used to evaluate the clinical failure risks of femoral stems by reporting distal migration, a measure of stem subsidence, when examining early migration characteristics. The migratory patterns of femoral stems, 24 months postoperatively, have provided a surrogate outcome measure to determine implant stabilisation and predict long-term performance and survivorship. RSA assessed femoral stem migration and provided comparison of the early migration characteristics with published data of a clinically established counterpart.

Methods

Twenty five patients undergoing primary total hip arthroplasty were implanted with a hydroxyapatite-coated femoral stem. The median age was 65 years (range, 43–75 years). During surgery tantalum markers were attached onto the distal tip and shoulder of the stem. Eight tantalum markers were inserted into the femur, four placed in each of the greater and lesser trochanter. RSA examinations were performed postoperatively at 4 to 5 days, 6, 12 and 24 months. Eleven patients who had complete RSA follow-up as well as the valid data from five patients were analysed to determine the movement of the femoral stem relative to the femur and were compared to the published data of a clinically established counterpart.

Introduction

Total hip arthroplasty (THA) instability is well documented to be more common in specific demographic groups. We report a retrospective analysis of the use of a dual mobility implant for primary hip replacements in selected patients at risk for dislocation. The aim of this study was to assess the long-term clinical and radiologic features associated with the dual mobility cup in case of primary THA.

Materials and Methods

At our institution 119 primary THA were performed in 114 patients (74 females and 40 males) at high risk of instability between January 2000 and December 2002. 84% of the patients had at least two risk factors for dislocation. The mean age was 71 years old (range, 21.4 to 93.2 years) at the time of the arthroplasty. A dual mobility cup was used in all cases. Clinical result was assessed using Harris Hip Score, and complications were determined by detailed review of the patient's records. Radiographs of the involved joint were reviewed to assess the position of the prosthesis and to look for osteolysis and signs of loosening of the implant.

Introduction

Revision procedures for unstable total hip arthroplasty have been reported with high failure rates. Many options have been proposed in such challenging cases, including dual mobility. The purpose of this retrospective study was to assess the clinical and radiologic features associated with the dual mobility cup in case of revisions for instability.

Materials and Methods

Sixty four total hip arthroplasties (62 patients) were revised for THA instability using a dual mobility cup at our institution between March 2000 and April 2008.

Mean age at reoperation was 67.3 year old (range, 35 to 98). The outcome of the revision procedure was assessed using the Harris Hip Score, and complications were determined by detailed review of the patient's records. Anteroposterior and lateral radiographs of the involved joint were reviewed to assess the position of the prosthesis and to look for osteolysis and signs of loosening of the implant.

Introduction

The value of collared stems for uncemented implants remains controversial. Some comparative studies have demonstrated advantages of collared stems regarding the potential for subsidence. Other studies with longer follow-up have shown no adverse effect of the use of a collar regarding the femoral component survivorship. To date, the adequate size of the collar with regards to the anatomy of the proximal femur has never been studied.

The goal of this study was to assess whether the size of the collar needs to be adjusted according to the size of the femoral component used, and according to the use of a standard or a lateralized component.

Materials and Method

102 CT of normal femurs have been divided into 2 groups of 51 femurs each. Each group has been analysed by 2 independant surgeons.

Each CT view passed through the axis of the proximal diaphysis and the center of the femoral head. The scale was 100%. Templates of femoral components have been set in order to reproduce the center of rotation and an optimal filling of the proximal femoral canal. Sizes of the femoral components as well as the need for standard or lateralized implants have been recorded. In order to determine the ideal size of the collar, the distance between the medial edge of the prothesis and the medial edge of the femur (so-called P-C distance) at the level of the neck cut (calcar) has been measured.

Introduction

Primary mechanical fixation and secondary biologic fixation determine the fixation of an uncemented femoral component. An optimized adequacy between the implant design and the proximal femur morphology allows to secure primary fixation.

The femoral antetorsion has to be considered in order to reproduce the center of rotation.

A so-called «corrected coronal plane » including the center of the femoral head has therefore been defined. The goal of this study was to evaluate the proximal metaphysal volume and to design a straight femoral component adapted to this corrected coronal plane.

Materials and Methods

205 CT-scans (performed in 151 males and 54 females free of hip arthritis) have been analyzed with a three-dimensional reconstruction. The mean age was 68.5 years (35–93).

A corrected coronal plane has been defined including the center of the femoral head and the axis of the intramedullary canal. Five levels of sections (at a defined distance from the center of the femoral head) have been selected: 12.5mm, 50mm, 70mm, 90mm and 120mm. Three intramedullary criteria have been studied: volume between the 50mm and the 90mm sections (C1), the medial-lateral distance of the intramedullary canal (C2) at the 50mm, 70mm, and 90mm levels, and the A-P distance (C3) at the 50mm, 70mm, and 90mm levels (respectively C3–50, C3–70, and C3–90). The femoral head diameter, the femoral offset and the canal flare index (CT flare) have also been measured.

(Introduction)

Metal on Metal (MoM) THA bearing as the second generation Total Hip Arthroplasty, widely came into use in Japan since 2000s. And it was expected to be able to ensure long-term use, the range of motion in the joints after surgeries, and the resistance to the dislocation, because MoM THAhad been considered to be able to use the large diameter head for its lower wear. However, there are some reports that the metal wear debris from MoM bearing surface generates the elevated serum ion level in the blood and the incidence of pseudotumor may occur subsequent to the metal wear debris. We performed MoM THA for 291 joints in 234 patients in our hospital since May 2005. But now, we refrain to use this. In this time, we will describe two cases of pseudotumor after implantation of MoM THA.

(Case1) Age 64 years, female

This case showed the hip osteoarthritis on the right side, and we performed MoM THA in 2005. After that, she had slipped just prior to the three-year postoperative check-up, andstarted swelling up, hip joint pain, and the rise in CRP. Then, we performed to remove pesudotumor in 2008 and her CRP turned into negative. However, she was repeating hip dislocation several times and an MRI showed recur of pseudotumor. Finally, we changed her metal liner into a polyethylene liner in 2012.

Introduction

Total knee arthroplasty is the standard treatment for advanced knee osteoarthritis. Patient-specific instrument (PSI)has been reported by several authors using different techniques produced by implant companies. The implant manufacturers produce PSI exclusively for their own knee implants and for easy straightforward cases. However, the PSI has become very expensive and unusable as a universal or an open platform. In addition, planning the implant is done by technicians and not by surgeons and needs long waiting time before surgery (6 weeks).

Methods

We proposed a new technique which is a device and method for preparing a knee joint in a patient undergoing TKA surgery of any knee implant (prosthesis). The device is patient specific, based on a method comprised of image-based 3D preoperative planning (CT, MRI or computed X-ray) to design the templates (PSI) that are used to perform the knee surgery by converting them to physical templates using computer-aided manufacturing such as computer numerical control (CNC) or additive-manufacturing technologies. The device and method are used for preparing a knee joint in a universal and open-platform fashion for any currently available knee implant.

Aim

To create a more “normal” anatomy for the repaired joint structure, which can be provided that by the following factors: (1) the available implant component require a normalized anatomical support structure, (2) the available repair components are designed and/or tested to only recreate and/or replicate more normalized anatomical structures and/or joint motion, (3) the surgeon is familiar and comfortable with more normalized joint motion and thus attempts to create such “normal” motion within the repaired anatomical structures.

Methods

We could discover a method of making an implant component for a knee joint of a patient which includes deriving information regarding a first joint line of the joint based on patient-specific information. This method also includes determining a planned level of resection for a first portion of a bone of the joint based on the patient-specific information. Further, the dimension of the implant component is determined based on the derived information regarding the first joint line and the planned level of resection for the first portion of the bone.

Also, we discovered an implant component for treating a patient's joint that includes a medial bone-facing surface. The medial bone-facing surface is positioned to engage a cut bone surface of a medial portion of a proximal tibia at a first level. The implant component also includes a lateral bone-facing surface. The lateral bone-facing surface is positioned to engage a cut bone surface of a lateral portion of the proximal tibia at a second level. The first level is offset from the second level. The implant component additionally includes one or more joint-facing surfaces having a curvature based on patient-specific information.

Furthermore, we discovered a system for treating a joint of a patient that includes one or more patient-specific instruments. The system further includes a medial tibial implant component. The medial tibial implant component has a bone-facing surface and a joint-facing surface. The joint-facing surface has a curvature based on patient-specific information. The system also includes a lateral tibial implant component, which has a bone-facing surface and a joint-facing surface. The joint-facing surface of the lateral tibial implant has a curvature based on patient-specific information. The bone-facing surface of the medial tibial implant component is configured to engage a cut bone surface that is at a level offset from the level of a cut bone surface to which the bone-facing surface of the lateral tibial implant component is configured to engage. The system further includes a femoral implant component, which has a joint-facing surface with a curvature based on patient-specific information.

Introduction

Computer aided surgery aims to improve surgical outcomes with computer guidance. Navigated Freehand bone Cutting (NFC) takes this further by eliminating the need for cumbersome mechanical jigs, while decreasing cutting time and complexity. To reduce the footprint of the NFC tracking system (currently NDI Polaris) we designed and implemented “On-Tool Tracking” (OTT), a novel miniaturized tracking system that mounts onto the cutting instruments (Fig. 1). This study investigates the accuracy of the 3D-measurements of the OTT system.

Materials and Methods

OTT was designed using off-the-shelf components to communicate as a wireless device. OTT consists of the following:

OTT communicates with a main PC using four wireless modules, based on three different technologies: Wi-Fi, Xbee, and UWB-USB.

OTT was secured on the upper actuator of a 5-axis Materials Testing Station (MTS-Systems), while the tracked, active wireless reference frame (RF) was locked in the lower actuator(s) (Fig. 2). The origin of OTT's camera system was aligned with the main vertical axis of the MTS and the RF origin set perpendicular to the cameras, with its origin coinciding with the same main vertical axis.

Using the MTS readings as reference (accuracy: 0.01mm/0.01º) for comparison, OTT software acquired multiple static measurements of the camera-rig vs. the RF pose at each location. X-translations and roll-angles were actuated by the MTS hydraulics; pitch and Y-translation were applied manually, while yaw was kept constant (0º).

Objective

Rotational malalignment of the femoral component still causes patellofemoral complications that result in failures in total knee arthroplasty (TKA). To achieve correct rotational alignment, a couple of anatomical landmarks have been proposed. Theoretically, transepicondylar axis has been demonstrated as a reliable rotational reference line, however, intraoperative identification of the transepicondylar axis is challenging in some cases. Therefore, surgeons usually estimate the transepicondylar axis from posterior condylar axis (PCA) using twist angle determined by the preoperative X-rays and CT. While PCA is the most apparent landmark, radiographs are not able to detect posterior condylar cartilage. In most osteoarthritic knees, the cartilage thickness of the posterior condyle is different between medial and lateral condyles. The purpose of this study is to evaluate the effect of the posterior condylar cartilage on rotational alignment of the femoral component in large number of arthritic patients. Furthermore, we investigated whether the effect of posterior condylar cartilage is different between osteoarthritis (OA) and rheumatoid arthritis (RA).

Methods

Ninety-nine OA knees and 36 RA knees were included. Detailed information is summarized in Table 1. All cases underwent TKA using navigation system. The institutional review board approved the study protocol and informed consent was obtained from each participants. To evaluate the effect of posterior condylar cartilage, we measured two different condylar twist angle (CTA) using navigation system and intraoperative fluoroscopy-based multi-planner reconstruction (MPR) images obtained by a mobile C-arm. To uniform the SEA in two different measuring systems, we temporary inserted a suture anchors in medial and lateral prominence. The CTA that does not include the posterior condylar cartilage (MPR CTA) is evaluated on MPR images and the CTA that does include the posterior condylar cartilage (Navi. CTA) is calculated by navigation system. The difference between these two angles corresponds to the effect of posterior condylar cartilage on the rotation of the femoral component (Fig. 1). The paired or unpaired t test was used to compare the obtained data. The statistics were performed using GraphPad Prism 6. A P value of 0.05 or less is considered as a significant difference.

Introduction

Controversy still exists as to whether total knee arthroplasty (TKA) provides reproducible knee kinematics during activities. In this study, we evaluated the in vivokinematics of stair-climbing after TKA using a 3D-to-2D model-to-image registration technique.

Patients and Methods

A total of twenty four knees in nineteen patients following cruciate-retaining (CR) or posterior-stabilized (PS) TKA were randomly included in the study. The twenty-four knees included 22 female knees and 2 male knees in patients aged 73 years. The pre-operative diagnosis was osteoarthritis in 22 knees and rheumatoid arthritis in 2 knees. The average follow-up period after surgery was 29 months, and average post-operative knee extension/flexion angle was 2°/121°. The average knee score was 93 and the average functional score was 77. Continuous sagittal radiological images were obtained during stair-climbing for each patient using a large flat panel detector. Anteroposterior (AP) tibiofemoral position, implant flexion, and axial rotation angles were determined in three dimensions using a 3D-to-2D model-to-image registration technique. In CR TKA, the minimum distances between the femoral trochlea and the intercondylar eminence of the tibial insert were measured using a CAD software program. In PS TKA, the minimum distances between the femoral cam and the posterior aspect of the tibial post and between the femoral trochlea and the anterior aspect of the tibial post were measured.

Introduction

Hip replacements are falling short of matching the life expectancy of coxarthritis patients, due to implanting THR in younger patients and due to increasingly active patients. The most frequently implanted hip prostheses use cross linked (XL) polyethylene (PE) on metal bearings in the USA and most of the Western world. Concerns remain in the long term around the potential of wear debris-induced aseptic loosening. Thus exploring lower-wearing alternative bearings remains a major research goal.

PEEK (poly-ether-ether-ketone) is a thermoplastic polymer with enhanced mechanical properties. This study compared the wear of PEEK to the wear of cross linked polyethylene, when sliding against cobalt chrome (CoCr) metallic counterfaces, and compared the wear of carbon-fibre reinforced (CFR)-PEEK to cross linked polyethylene when sliding against metallic and ceramic counterfaces under different contact stresses within the hip joint.

Methods

The following materials were studied: unfilled PEEK (OPTIMA, Invibio) and CFR-PEEK (MOTIS, Invibio) against either high carbon (HC) CoCr or Biolox Delta ceramic plates. The comparative control material was a moderately cross-linked PE (Marathon, DePuy Synthes).

A simple geometry wear study was undertaken. A rotational motion of ±30° across a sliding distance of ±28 mm (cross shear of 0.087), and contact pressures of 1.6 or 4 MPa were applied. The lubricant was 25% (v/v) bovine serum and the wear test was conducted for 1 million cycles at 1 Hz. Wear was assessed gravimetrically. A validated soak control method was used to adjust for serum absorption-induced mass changes during the wear test. Surface profilometry was assessed pre and post wear test.

Introduction

Optimal alignment of the acetabulum cup component is crucial for good outcome of Total Hip Arthroplasty (THA). A patient-specific instrumentation (PSI) for cup alignment manufactured by 3D printing might improve cup alignment in conventional THAs with patient's lateral decubitus position. In this study, we developed PSI for cup alignment which transferred preoperatively planned cup alignment to the operation room as a linear visual reference(Figure 1), then investigated its accuracy in terms of fitting of PSI on the bony surface and angle deviation between pre- and post-operative cup alignments.

Methods

3-Dimensional bone models created from CT images of both sides of 6 cadaveric specimens were used in the current study. In the first experiment (first 3 specimens and six hips), we designed PSI to fit on the acetabular rim, and we inserted a Kirschner wire (K-wire) through PSI after PSI's fitting. In the second experiment (remaining 3 specimens and six hips), after the same steps like the first experiment were done, we reamed and finally impacted plastic cups with the visual reference of the K-wire. Using postoperative CT images taken after both experiments, we measured deviation of the K-wire placement for the first experiment, and measured deviation of the cup placement from planned cup alignment.

Introduction

A variety of porous coatings and substrates have been used to obtain fixation at the bone-implant interface. Clinical studies of porous tantalum, have shown radiographically well-fixed implants with limited cases of loosening. However, there has been limited retrieval analysis of porous tantalum hip implants. The purpose of this study was to investigate factors affecting bone ingrowth into porous tantalum hip implants.

Methods

126 porous tantalum acetabular shells and 7 femoral stems, were collected under an IRB-approved multicenter retrieval program. Acetabular shells that were grossly loose, cemented or complex revisions were excluded. Shells with visible bone on the surface were chosen. 20 acetabular shells (10 primary) and all femoral stems were dehydrated, embedded, sectioned, polished and bSEM imaged (Figure-1). Main shell revision reasons were infection (n=10,50%), femoral loosening (n=3,15%) and instability (n=3,15%). Analyzed implants were implanted for 2.3±1.7 years (shells) and 0.3±0.3 years (stems). Eight slices per shell and 5–7 slices per stem were analyzed. The analysis included bone area/pore area (BA/PA), BA/PA zonal depth analysis, extent of ingrowth and maximum depth of bone ingrowth. BA/PA zone depths were: Zone-1 (0–500um), Zone-2 (500–1000um) and Zone-3 (1000um-full depth). Nonparametric statistical tests investigated differences in bone measurements by location within an implant and implant type (Friedman's Variance and Kruskal-Wallis). Post-hoc Dunn tests were completed for subsequent pairwise comparisons. Spearman's rank correlation identified correlations between bone measurements and patient related variables (implantation time, age, height, weight, UCLA Activity Score). Statistical analyses were performed using PASW Statistics package.

Introduction

3D-to-2D model registration technique has been used for evaluating 3D kinematics from 3D surface models of the prostheses or bones and radiographic image sequences. However, no studies have employed these techniques to evaluate in vivo hip kinematics under dynamic weight-bearing conditions. The purposes of this study were to evaluate kinematics of healthy hips and also hips with osteoarthritis (OA) prior to total hip arthroplasty (THA) during four different weight-bearing activities using 3D-to-2D model-to-image registration technique.

Measurement

Dynamic hip kinematics during gait, squatting, chair-rising, and twisting were analyzed for six healthy subjects and eleven patients with osteoarthritis (OA). Continuous anteroposterior radiographic images were recorded using a flat panel X-ray detector (Fig. 1), and each hip joint was scanned by computed tomography (CT). The 3D positions and orientations of the pelvis and femur in movement cycle were determined using a 3D-to-2D model-to-image registration technique. A matching algorithm maximizing correlations between density-based digitally reconstructed radiographs from CT data and the radiographic images was applied (Fig. 2). The relative positions and orientations of the pelvis with respect to the world coordinate systems were defined as pelvic movements (anterior-posterior tilt, contralateral-ipsilateral rotation, Fig. 3b and c), and those of the femur with respect to the world coordinate systems were defined as femoral movements (flexion-extension, internal-external rotation, Fig. 3d). We also defined the relative positions and orientations of the femur for the pelvis as hip movements (flexion-extension, internal-external rotation, Fig. 3e and f).

Objectives

The approach in total knee arthroplasty (TKA) with severe valgus deformity is controversial. The lateral parapatellar approach has been proposed for several years, but surgical technique of this approach was unusual and difficult. Therefore, we have consistently been selected medial parapatellar approach (MPP) for all cases. In this study, we investigated the short term results of TKA for severe valgus deformity with MPP about clinical and radiographic assessment.

Methods

Seven knees in seven cases of severe valgus knees with stand femorotibial angle (FTA) less than 160 degrees were enrolled. Osteoarthritis were 6 cases, hemophilic arthropathy was 1 case and no rheumatoid arthritis case. There were 6 female and 1 male, and mean age was 63.6 years (41–75 years). Duration of follow up ranged 3 months to 22.5 months, with mean of 10.9 months. We compared alignment on standing radiograph, range of motion (ROM), the Japanese Orthopaedic Association (the JOA) score for osteoarthritic knee pre/postoperatively, and examined post operative complication retrospectively.

Introduction

Fixation patterns of cementless stem were known as proximal or distal part. Distal fixation was seen in fully porous coated stem and stress shielding of the proximal femur was indicative. These phenomena did not lower the clinical results, but technical difficulties were more and more in revision surgery because of infection or dislocation. There was lot of reports that alendronate was effective for treatment of osteoporosis by induction of apoptosis in osteoclasts. We can expect alendronate to modify the bone quality around the stem after cementless THA.

Objectives

We studied prospectively that quantitative computed tomography (QCT) measured bone mineral density around the stem between alendronate group and control. We tried to clarify that stress shielding after cementless THA can be prevented by use of alendronate or not.

Introduction

Pseudotumors have been reported following metal-on-metal total hip arthroplasty (THA); however, the natural history and longitudinal imaging findings of pseudotumors have yet to be fully analyzed. Our hypothesis was that pseudotumor size might change over time following metal-on-metal THA. This hypothesis was studied longitudinally using magnetic resonance imaging (MRI).

Materials and Methods

Screening for pseudotumors was performed using MRI after large-diameter metal-on-metal THA. Initial MRI was conducted at a mean of 36 months postoperatively. Follow-up MRI was performed at a mean of 20 months after the detection of 24 pseudotumors in 20 asymptomatic patients. Pseudotumors were classified as cystic, solid, and mixed types. Fourteen hips were characterized as cystic type and 10 hips were defined as mixed type. There were three men and 17 women with a mean age of 63 years. Pseudotumor size was determined on MRI by manually outlining the greatest size of the mass. Serum cobalt and chromium ion levels were measured in nine patients with unilateral THA at the time of MRI. Statistical analysis was performed using the Kruskal-Wallis test and chi square test to compare age, gender, BMI, head diameter, cup inclination, cup anteversion, and pseudotumor type among changes of pseudotumor size. We compared the pseudotumor size for the three groups (increase in size, no change, decrease in size) using Kruskal-Wallis test and Mann-Whitney U test. Wilcoxon signed-rank test was used to compare median serum metal ion levels over time. A p value < 0.05 was considered significant. This study was approved by the ethics committee of our institution, and all patients provided informed consent.

Introduction

After aseptic loosening, dislocation of hip prosthesis is the most frequent complication in patients with hip arthroplasty, with annual cost of treatment from 70 to 100 million dollar (American estimation)

Materials and methods

In the periods between January 2000 and December 2005, 359 hip arthroplasty surgeries were done in orthopedic clinic of Torretti Hospital of Ancona – Italy as following: 279 cases of primary hip arthroplasty and 80 cases of revision hip prosthesis with rate of dislocation: Total number of cases are 24 from 359 (6.6%) cases as following: 15 cases (5,3%) after primary hip arthroplasty and with rate of dislocation 9 cases (11,2%) after revision hip arthroplasty, all the dislocated case are followed retrospectively as following:

Introduction

The metal-backed patella was originally designed to address shortcomings found with cemented, all-polyethylene patellae. However, complications relating to an all-polyethylene patella were reported to account for up to half of all knee revisions. At the same time, good fixation with bone ingrowth was observed in both titanium and cobalt chromium porous-coated patellae. The advantages provided by using a metal-backed patella, such as uniform load sharing, decreased polyethylene deformation, and potential for biological fixation, may be unjustly outweighed by the fear of patellar component failure; high rates of failure have not been inherent to all metal-backed patella designs. Over the past decade, we have used a metal-backed patella design with excellent results that may be due largely to the design features of the component. Also, we believe there are certain selection criteria that should be strictly adhered to when implanting metal-backed patellae. Correct selection criteria and improved component design strongly indicate the use of press-fit metal-backed patellae.

Methods

This single-center study was designed to conduct clinical and independent radiographic review of primary metal-backed, press-fit patella patients with a minimum five-year follow-up. Potential patients were recruited from a group of existing metal-backed patella patients within the principal investigator's medical practice. All patients recruited for this study were required to have undergone primary knee replacement surgery at least five years prior to clinical and radiographic evaluation. Patients were included if they had a diagnosis of noninflammatory degenerative joint disease. Patients with a BMI >40 were excluded from this study. Radiographic analysis was conducted by an independent reviewer according to the current Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System. Any radiographs that the reviewer deemed questionable were shown to a second independent orthopaedic surgeon for review, comment, and validation of observations. Kaplan-Meier survivorship was determined for all metal-backed patellae. For survival analysis, only knees with radiographic data were included (74 knees). KSS, WOMAC, and SF-36 scores were calculated also.

Background

Revision hip arthroplasty for excessive bone loss because of osteolysis or infection is difficult theme. Bone grafting is essential technique for bone loss and need of allograft is increasing. Recently, many hospital bone banks are established in Japan. The aim of this study is investigate efficacy and safety of allograft in our hospital bone bank.

Material and method

We evaluated management, result and complication of allografts retrieved from living donors in our institute.

Introduction

Dislocation continues to be a common complication of total hip arthroplasty (THA). Many factors affect the prevalence of dislocation after THA, including soft tissue laxity, surgical approach, component position, patient factors, and component design [1]. Achieving proper intraoperative soft tissue tension is one of the surgical goals to reduce the risk of the dislocation. However, reports of the intraoperative soft tissue tension measurements have not been enough yet. One way to quantify the intraoperative soft tissue tension is to measure joint forces using an instrumented prosthesis. Hence, we have developed a sensor-instrumented modular femoral head of THA to measure the soft-tissue tension intraoperatively. The goal of this study was to design and calibrate the sensor.

Materials and Methods

The sensor-instrumented modular femoral head that we developed was made of polycarbonate with four linear strain gauges (BTM-1C, Tokyo Sokki Kenkyujo Co., Ltd., JP). To fabricate the sensor, four penetrant holes (1.6 millimeter in diameter), parallel to the coordinate axes were produced (Fig1). The strain gauges were embedded on inside wall of these holes. Finally, the holes were filled by epoxy resin (A-2 adhesive, Tokyo Sokki Kenkyujo Co., Ltd., JP). For calibration study, the sensor was fixed in a clamping block of an angle vice to permit change of force directions. The calibration jig with the angle vice was placed on top of a low-friction x-y translation table that eliminated horizontal constrains. Known forces (F_i) were applied by a standard material testing machine (Instron4204, INSTRON, Norwood, MA) through a polyethylene insert (Fig. 2). Two different series of forces were applied. One is that force values were increased from zero to 600 N on the z axis. And the other force pattern is 600 N forces were applied by changing force angles. The external force vector (F_i) can be expressed in terms of the strain gauge outputs as follows:

where T is a calibration matrix and S_i corresponds to the outputs of the strain gauges. Calibration errors were calculated according to well-established methods [2].

(Introduction)

In Total Knee Arthroplasty (TKA), closed drains have been conventionally used to prevent hematoma. Recently reported “no-drain” methods have been demonstrated to be safe and effective, especially for decreasing hemorrhage. However, there has been no report of a major study on a no-drain method in simultaneous bilateral TKA, only a few small studies. Therefore, this study evaluated the efficacy of no-drain placement in simultaneous bilateral TKA.

(Methods)

Our study included 75 patients (150joints) with preoperative hemoglobin(Hb) level of at least 11.0 g/dl who underwent simultaneous bilateral TKA performed by the same surgeon in our department between January 2012 and December 2013.

There were 12men and 63women, of average age 70.7 ± 7.9years (mean ± SD) and BMI 25.6± 3.8 (mean ± SD). Among them 72 patients had knee osteoarthritis and 3 patients had rheumatoid arthritis. The patella was not replaced in any of the cases. TKAs were performed separately on each knee. A tourniquet was applied between the initial skin incision and the postoperative dressing, and 1000 mg of tranexamic acid was injected into each joint after wound closure.

Background

Sciatic nerve palsy is a relatively rare, but one of the serious complications after total hip arthroplasty (THA). The prevalence of nerve palsy after THA has been reported to range from 0.3% to 3.7%. Previous authors have speculated that causes could include overlengthening, compression from a hematoma, from extruded metylmethacrylate, or from retractor placement, or laceration from a screw used in the acetabular component. Leg lengthening more than 4 cm was associated with sciatic nerve palsy in the past literature. But there is no report about maximum safety leg lengthening to prevent sciatic nerve palsy significantly. The purpose of this study was to identify the safety rage of leg lengthening to prevent sciatic nerve palsy in THA for the patients with adult hip dislocation.

Methods

Forty two consecutive patients47 jointswith Crowe type â?¢ or â?£ were performed THA. Nine joints were Crowe type â?¢ and thirty eight joints were type â?£ in this study.

All patients were female. The average age at the time of surgery was 63.3 years (range, 40–77 years). The average patient body weight was 50.5 kg and the average height was 150 cm (body mass index: 22.3 kg/m²⁾. The average follow-up was 9.9 years (range, 1–21). See Table1 The socket was placed at the level of the original acetabulum, and femoral shortening osteotomy was performed in 27 joints. Leg lengthening (LL) was defined the vertical distance from the tip of greater trochanter to the tear drop line. The mean LL was 3.1 cm (range, 1.5–6.7 cm). Clinical Harris hip score and sciatic nerve palsy was retrospectively assessed from the patients records. The correlation between LL, the percent LL (cm) divided by body height (cm) (%LL/BH) and the incidence of sciatic nerve palsy was investigated.

Introduction

Correct alignment is important for a successful result after total knee arthroplasty (TKA). During most activities of daily living, the knee is loaded not only in full extension but also in mid-flexion. However, there are few methods to evaluate mid-flexion varus-valgus alignment, despite its clinical significance. Computer navigation systems are useful for intra-operative monitoring of joint positioning and movements. Knee ligaments contribute to induce kinematics of the joint. It is likely that the presence of posterior cruciate ligament has some effects on kinematics throughout flexion. The purpose of this study was to evaluate changes in the varus–valgus alignment of the femoral–tibial mechanical axis in each flexion angle before and after TKA by using a navigation system, and to evaluate varus–valgus kinematic patterns throughout flexion, and compare preoperative and postoperative changes of kinematic patterns in CR-TKA and PS-TKA procedures.

Material and Method

Forty knees that underwent TKA with computer navigation system were evaluated (CR-TKA 20; PS-TKA 20). CR and PS TKRs were implanted in alternating sequence. The investigator applied manual mild passive knee flexion, while moving the leg from full extension to flexion and the varus-valgus angle of femoral-tibial mechanical axis was measured automatically by the navigation system at every 10 ° throughout flexion. We classified kinematic patterns in the varus–valgus direction throughout flexion.

Background

Constrained condylar knees are used infrequently but are successful for the treatment of the primary or revision knee with ligamentous instability and bony defect. The purpose of the present study is retrospectively analyze clinical and radiological outcome of primary and revision total knee arthroplasty with condylar constrained knee (CCK) prosthesis at a minimum of 5 years.

Methods

Fourteen knees underwent total knee arthroplasty with CCK prosthesis, performed between 2003 and 2009. The average age of the patients at the time of the surgery was 71.4 years (range, 47 to 88 years). The reason for the operation was primary (osteoarthritis) in 2, revision due to aseptic loosening in 9 and infection after total knee arthroplasty in 4 knees. NexGen LCCK was used in all cases. The mean follow-up period was 91months (range, 60 to 128 month).

Background

Large head metal on metal total hip arthroplasty MOM THA have been consistently shown substantial improvement in wear performance compared with metal on polyethylene articulations. Large diameter femoral heads theoretically can reduce dislocation risk by increasing range of motion before impingement, increasing prosthetic jump distance. However, early failure associated with adverse local tissue reactions (ALTRs) to metal debris is an emerging problem after MOM THA. The purpose of this study was to evaluate mid-term results of MOM THA.

Materials and Methods

Twenty-five patients, 28 hips were included in this study. The average age of the patients at the time of surgery was 66.9 years. Three patients were men and 22 were women. MOM THAs were performed using 28 PINNACLE Cup system (DepPuy) (C-STEM: 23, S-ROM: 5) with posterior approach and head size of 36mm. Twenty-five primary THAs due to osteoarthritis in 22 cases and rheumatoid arthritis (RA) in one, and two revisions due to recurrent dislocation THA patients, were performed. The average follow up was 56.7 months. Evaluation items are JOA score, cup anteversion /lateral opening angle, and complications. Indication of the system were applied for patients with high risk of dislocation such as recurrent dislocation in primary and/or THAs, posterior pelvic tilt, elderly, RA and mental disorders.

1. Introduction

Such a Total Knee Arthroplasty (TKA) that is capable of making high knee flexion has been long awaited for the Asian and Muslim people. Our research group has developed the TKA possible to attain complete deep knee flexion such as seiza sitting. Yet as seiza is peculiar to the Japanese, other strategies will be necessary for our TKA to be on the overseas market. Still it is impractical to prepare many kinds of modifications of our TKA to meet various demands from every country/region. To this end, we contrived a way to modularize the post-cum alignment of our TKA in order to facilitate the following three activities containing high knee flexion: praying for the Muslim, gardening or golfing for the Westerner, sedentary siting on a floor for the Asian. We performed simulation and experiment, such as a mathematical model analysis, FEM analysis and a cadaveric study, thereby determining the optimal combination of moduli for the above activities respectively.

2. Methods

We modularized the post-cum alignment by three parameters in three levels respectively (Fig.1). The shape of the post's sagittal section and the total shape of cum were unchanged. The three parameters for modularization were the post location which was shifted anterior and posterior by 5 mm from the neutral position, the post inclination which was inclined forward and backward by 5° from the vertical, and the radius of curvature of the post's horizontal section which was increased and decreased by 2 mm from the original value. It is crucial to decrease contact stress between the post and cum during praying for the Muslim and during gardening or golfing for the Westerner, which would be realized by choosing the optimal location and inclination of post when kneeling for the Muslim and when squatting for the Westerner respectively (Fig.2). As for the Asian, it is desirable for them to perform various kinds of sedentary sittings on a floor without difficulties, which would be facilitated by choosing the optimal radius of curvature value to increase range of rotation when the knee is in high-flexion (Fig.2). First we performed a mathematical model analysis to introduce the kinetic data during sit-to-stand activities. Then by using the above kinetic data we performed the FEM analysis to determine the contact stress between the post and cum during praying, gardening or golfing. Finally we carried out the cadaveric study to determine the range of rotation at high flexion of the knee.

Introduction

Computed tomography (CT) can be utilized to design patient specific instruments (PSI) for total knee arthroplasty (TKA). The PSI preoperative plans predict bone resection, anterior-posterior implant position, implant rotation and implant size. The purpose of this study was to compare preoperatively predicted implant sizes (tibia and femur) to the actual implanted sizes. Data were compiled from two surgeons, one in the United Kingdom (Surgeon 1, cruciate retaining) and one in the United States (Surgeon 2, posterior stabilizing). Both used the same primary TKA implant systems (Sigma® and Attune®; DePuySynthes®, Warsaw, Indiana). This is the largest comparison of CT-based PSI size accuracy between two implant systems.

Methods

An international cohort of 396 CT-based PSI-TKA preoperative plans (TruMatch®)were compared to postoperative implant records. Data were retrospectively analyzed for Sigma®(n=351) and Attune® (n=45), both as separate cohorts and as a combined cohort (Sigma® + Attune®). Three analyses were performed: Tibia and femur plan accuracy, major size changes (femoral size change or tibial size change resulting in a femoral size change) and minor size changes (tibial size change not impacting femoral size). Inter-rater reliability analyses using ICC (intra-class correlation) and the Kappa statistic were performed to determine reliability and agreement among the groups.

Combined TKA implant data (Sigma® + Attune®) for surgeons 1 and 2 were compared for accuracy between users utilizing different implant designs, cruciate retaining (CR) versus posterior stabilized (PS).

Introduction

In these three years, many troubles have occurred in the arthroplasty by hip joint prostheses with metal on metal sliding surfaces. Anomalous reaction including a pseudotumor, which is supposed to be caused by the metal ions released from the implant surfaces, is the most serious problem for the patients¹⁾. This problem seriously confused us because there is the fact that ion release has not hardly occurred between a head and an acetabulum, where usual wear proceeds. The important clue was the stain that was sometimes found on the surfaces of the taper junction of retrieved prostheses. This stain has been generally estimated the evidence of the fretting corrosion. It has not been clarified why short range sliding enhances the corrosion, yet. In the present study, to elucidate this problem, we observed the behavior of the passive film of implant surfaces under the sliding conditions of fretting, which is presumed on the taper junction.

Materials and Methods

In the present study, electric potential was measured as an indicator to assess the removal of the passive film of cobalt chromium (CoCr) alloy under the fretting conditions. A wear simulator (FPR-2100, RHESCA, Tokyo, Japan) was used for the testing apparatus with reciprocating motion. A Co-28Cr-6Mo alloy pin (Smith & Nepew, London, UK) specimen was 10 mm in diameter and abraded with the common material plate (Fig. 1). A load of 1 N was applied to a pin. The electronic potential between the pin and the Ag/AgCl reference electrode (HX-R5, HOKUTO DENKO, Tokyo, Japan) soaking in the PBS(−) as simulated biological fluid were measured using a high impedance electrometer (HE-104, HOKUTO DENKO, Tokyo, Japan) (Fig. 2). The sliding width was chosen 0.5–10 mm. The reciprocating cycle was chosen 0.5–2 Hz. The changes in the electronic potential of CoCr alloy were recorded during the sliding motion together with under the static conditions before and after the sliding motion.

Background

There are some critical points of Cruciate retaining (CR) TKA. We recognized that it is one of the most important issue how to manage for release of PCL contracture. PCL contracture would lead to poor ROM, stiff or painful knee after CR TKA. PCL release at insertion of femoral / tibial side or cut in PCL itself, “pie craft” were reported. However, for retaining of PCL function after TKA, peeling off PCL itself would be not desirable. Therefore, we proposed to perform V shape-osteotomy at PCL insertion of tibia with osteotome (Fig.1,2) and cancellous bone graft at osteotomy site to get bony union (V-shape osteotomy with cancellous bone graft: VOCG). We would present how to perform VOCG at CR TKA and clinical results.

Patients and Methods

188 knees in 126 patients were received NRG CR TKA (Stryker) at Nagano Matsushiro General Hospital between February 2008 and August 2009. Mean age at operation was 75.1±5.9 years old. The indications for VOCG were positive of POLO test positive, inadequate soft tissue balance because of PCL contracture, or poor pre-operative ROM et al. All patients were reviewed with clinical and radiographic assessments. Clinical evaluation was carried out using the Knee Society Score (knee score and functional score). The range of motion (ROM) was pre- and post-operatively. In order to evaluate the effect of VOCG, clinical outcomes were compared between two groups (with VOCG vs without VOCG).

Introduction

Locking plates can provide greater stability than conventional plates; however, reports revealed that fractures had a high incidence of failure without medial column support; the mechanical support of medial column could play a significant role in humeral fractures. Recent studies have demonstrated the importance of intramedullary strut in proximal humeral fracture fixation, the relationship to mechanical stability and supporting position of the strut remain unclear. The purpose of this study was to evaluate the influence of position of the intramedullary strut on the stability of proximal humeral fractures using a locking plate.

Materials and methods

Ten humeral sawbone (Synbone) and locked plates (Synthes, cloverleaf plate), with and without augmented intramedullary strut (five in each group) for proximal humerus fractures, were tested using material testing machine to validate the finite element model. A 10 mm osteotomy was performed at surgical neck and a strut graft (10 cm in length) was inserted into the fracture region to lift the head superiorly. Each specimen was statically tested at a rate of 5 mm/min until failure. To build the finite element (FE) model, 64-slices CT images were converted to create a 3D solid model. The material properties of screws and plates were modeled as isotropic and linear elastic, with an elastic modulus of 110 GPa, (Poisson's ratio, n=0.3). The Young's moduli of cortical and cancellous bones were 17 GPa and 500 MPa (n=0.4), respectively. Three alter shifting toward far cortex by 1, 2, and 3 mm in humeral canal were installed in the simulating model.

Introduction

Distal femur fracture is a critical issue in orthopedic trauma, because it is difficult to manage especially in cases with intra-articular fracture. Osteoporosis may cause instability of implant and increase complications. Few studies investigate on the stability of distal femur osteoporotic fracture and the behaviors under cycling. Our hypothesis was that the stiffness of construct would decrease as cycling in osteoporotic bone.

Materials and Methods

Seven cadaver specimens were used in this study. Relative bone density for each specimen was evaluated using CT scanning by three known calibration phantoms scanned simultaneously with the specimen. All cadaver specimens were divided normal (group 1) and osteoporosis (group 2) in accordance with the bone density. The titanium distal femur locking plates with 6 screws placed in distal femur condyle and 4 in shaft. A 10 mm gap with 65 mm proximal to the center of articular surface and a vertical fractural line between intra-articular were created to simulate AO C2 type fracture. Each specimen was cyclically loaded in two-phase at a frequency of 2 Hz. Phase 1 was set at 1000 N for 10000 cycles. In phase 2, the load was set at 2000 N for 10000 cycles. Then, the specimen was loaded up to failure at a rate of 5 mm/min. Stiffness was evaluated from the linear portion of load-displacement curve at 2000 cycle interval.

Purpose

Short metaphyseal fitting femoral stems convey stress to proximal femur and have no distal fixation. They have advantages in that there is no thigh pain and no bone loss due to stress shielding, but there is a concern for weakened fixation. So the authors evaluated whether short metaphyseal fitting femoral stems, which have only metaphyseal and no diaphyseal fixation, can acquire sufficient stability.

Materials & methods

39 cases of 36 patients who undervent uncemented total hip arthroplasty with DePuy Proxima^TM (Johnson & Johnson orthopaedics, New Milton, UK) short metaphyseal fitting femoral stems from August 2009 to September 2011 were retrospectively evaluated. There were 19 male and 20 female cases. The mean follow-up period was 35.8(21.8∼49.2) months. Harris hip scores, WOMAC scores, UCLA scores, and presence of femoral pain were evaluated to assess clinical outcome. Femoral radiolucency in coronal and sagittal views of the hip, femoral stem loosening, and displacement was measured to evaluate radiological outcome. Distance between femoral stem and cortical bone was also measured to assess the relationship with radiolucency and loosening according to degree of contact.

Introduction

Biomechanists have been trying to obtain integrated and accurate human motion data. However, it is not so easy, because some have limitation of accuracy, some have limitation of the observation area, and some are expensive.

For example, motion capturing can obtain whole body motion data, but needs space, is expensive, but only surface motion could be obtained. So is not so sensitive for the bone rotation. Sensors of pressure, acceleration, and so forth are less expensive and less hard to use, but the data are limited. 2D–3D shape matching such as Jointtrack can describe bone motion including rotation, but the detectable area is limited by the size of flat panel fluoroscopy.

In this study, we have combined multiple joint motion analysis by Jointtrack and reconstructed full lower extremities' motion.

Method

Pelvis, bilateral femurs, and bilateral tibiae geometries were obtained from CAT scan using Mimics®. Gait motion fluoroscopy was done on a treadmill around hip joints and knee joints (Fig.1). On each heal thin film switch was attached and connected to electrically driven metal flag which can be recorded in fluoroscopic images on heal strikes. Images of five gait cycles were taken with 15Hz and every image was sorted by the percentage of gait cycle, and then processed by Jointtrack. Centre of femoral head of observing side was defined as our origin. Using treadmill, the walking direction could be uniquely defined. From the femoral 3D displacement and rotation, knee position can be calculated. The same procedures were done for the knee assessment, mutual coordinate of hip centre from the knee can be calculated. All of them are sorted by the percentage of the gait cycle too. Combining data from hip and knee, complete lower extremities' motion could be described. Regression analyses of x, y, z coordinates of femurs from hip and from knee were done to evaluate the accuracy.

Motion capture of floor gait and treadmill gait were done to evaluate the difference. (Fig.2)

Introduction

Recently, computer-aided orthopaedic surgery has enabled three dimensional (3D) preoperative planning, navigation systems and patient matched instrument, and they provide good clinical results in total knee arthroplasty. However, the preoperative planning methods and the criteria in total elbow arthroplasty (TEA) still have not sufficiently established due to the uncertainty of 3D anatomical geometry of the elbow joints. In order to clarify the 3D anatomical geometry, this study measured 3D bone models of the normal elbow joints. Additionally this study attempted to apply the 3D preoperative planning to ordinary surgery. Then the postoperative position of implant has evaluated as compared with the position in 3D preoperative planning.

Methods

Three dimensional bone measurements on 4 normal cases were performed. Three dimensional bone models were constructed with CT image using Bone Viewer®(ORTHREE Co., Ltd.). TEA was performed with FINE® Total Elbow System (Nakashima Medical Co., Ltd.) for 3 rheumatoid arthritis (RA) cases (Fig. 1). Three dimensional preoperative planning was based on this bone measurement, and postoperative position of implant were evaluated. The postoperative assessments were evaluated by superimposing preoperative planning image on postoperative CT image using Bone Simulator® (ORTHREE Co., Ltd.). This study only covers humeral part.

Introduction

In THA of DDH cases, sometimes shortening and/or derotational subtrochanteric osteotomy is required, for cases with high hip center and/or high anteversion. Initial fixation is one of the most important problems after subtrochanteric osteotomy. To prevent rotational displacement V-osteotomy or step osteotomy is often used. Even though until the osteotomy part unites, additional fixation is required. When a stem with distal load transfer was used body weight can be transferred to healthy part, so early full weight bearing should be expected. However, the muscles around hip joint can pull up proximal part, so it would be possible osteotomy part to be split. When a stem with proximal load transfer, body weight would be loaded on non united osteotomy part. So full weight bearing could sometimes be postponed. A stem that has both proximal and distal load transfer, and has facility for prevent rotation, those situations would possibly be simply solved.

Lima (Italy) has a proximal load transfer conical stem with fins “Modulus” and a distal load transfer conical stem “Revision.” Combining these two stems, a stem as explained prior was designed. In the present study, applicability of the stem for cases such as subtrochanteric osteotomy was assessed.

Materials and Methods

The stem geometry data were provided by the maker. Forty CAT scan DICOM data, 12 male, 28 female, 58+/−13.8 Y.O. were transferred to STL geometry data using Mimics®. Then using Magics® fit studies were done. For each femur, most suitable size of conventional “Modulus” and double conical stem “Modulus R” were selected to have tight fit making greater trochanter top height as head center height, then the area where stem core attaches to the inside surface of the canal were determined.

Introduction

Since 1989, we have been developing lateral flare stem. The concept of lateral flare stem is to deliver proximal part big enough to fill the proximal cavity that most of the cement stems can fill and most of the cementless stems cannot. Also having distal part polished, much less distal load transfer occurs than cement stem. Thus, we can expect high proximal load transfer to prevent stress shielding. To deliver lateral flare stem, straight insertion path cannot be available, as proximal lateral part to fill inside the greater throchanter collides to the greater trochanter. So 3-Dimension insertion path was calculated to deliver that part through the narrow made by neck osteotomy. The first generation of the lateral flare stem was custom made. The second generation was designed as an off-the-shelf stem from what we have learned by the experience of custom stems. With the third generation, the stem was shortened to achieve more proximal load transfer.

Direct Anterior Approach (DAA) developed by Judet is one of less invasive hip approach. With a stem with straight insertion path, the extended line of proximal femoral axis should come out of the skin. To achieve this position, proximal end of the femur has to be fully pulled up. (Fig.1) Some of the cases would be able to be lifted up but some have difficulty. Using lateral flare stem with curved 3 dimensional insertion path, even the axis extension does not come out of the skin, it would be expected to be inserted. In the present study, 3D insertion path of the lateral flare short stem for DAA was analyzed.

Materials and methods

Preoperative CAT scan data were transferred to STL data by Mimics®. The procedures after that were done by Magics®. First, neck osteotomy was done, externally rotated, and mild extension that doesn't make the axis come out of the skin was added. Then insertion path was verified keeping the stem attached medial sidewall of the canal (Fig. 2). In actual case, skin translation and pelvis rotation was assessed by 3D scanner. (Fig. 3)

Introduction

During THA in lateral position, keeping accurate lateral position is very important for obtaining good cup position. We normally use two kinds of hip positioner, but sometimes we can only use universal positioner provided with operational table. The pelvic tilt can be changed by surgical procedures such as traction, dislocation, reduction and so forth. In the present study, pre-op and post-op pelvic tilt was assessed using Kinect (Xbox 360′s sensor) as 3D scanner.

Materials and Methods

As a 3D scanner, “Kinect®” was used (Fig. 1) with scanning software “Artec Studio 9 ®”. First, accuracy of the scanning system was validated, then 6 postero-lateral approach hip replacement with lateral position surgery cases (Fig.2) (1 male and 5 female, average 55.5 y.o., average BMI 27.6, IMP® positioner: 3 cases, Kyocera positioner: 2 cases, universal fixator provided with surgical table: 1 case), one direct anterior approach case, and one supine antero lateral case (Fig. 3) were scanned pre and post operatively. Pelvic tilts were assessed using tableside rails or edges of positioner that is tightly fixed to the table, as the reference.

Introduction

Many factors can influence post-operative kinematics after total knee arthroplasty (TKA). These factors include intraoperative surgical conditions such as ligament release or quantity of bone resection as well as differences in implant design. Release of the medial collateral ligament (MCL) is commonly performed to allow correction of varus knee. Precise biomechanical knowledge of the individual components of the MCL is critical for proper MCL release during TKA. The purpose of this study was to define the influences of the deep medial collateral ligament (dMCL) and the posterior oblique ligament (POL) on valgus and rotatory stability in TKA.

Materials and Methods

This study used six fresh-frozen cadaveric knees with intact cruciate ligaments. All TKA procedures were performed by the same surgeon using CR-TKA with a CT-free navigation system. Each knee was tested at 0°, 20°, 30°, 60°, and 90° of flexion. One sequential sectioning sequence was performed on each knee, beginning with femoral arthroplasty only (S1), and thereafter sequentially, medial half tibial resection with spacer (S2), ACL cut (S3), tibial arthroplasty (S4), release of the dMCL (S5), and finally, release of the POL (S6). The same examiner applied all external loads of 10 N-m valgus and 5 N-m internal and external rotation torques at each flexion angle and for each cut state. All data were analyzed statistically using two-way ANOVA and paired t-test. A significant difference was determined to be present for P < .05.

INTRODUCTION

Although the most commonly used method of femoral component alignment in total knee arthroplasty (TKA) is an intramedullary (IM) guides, this method demonstrated a limited degree of accuracy. The purpose of this study was to assess whether a portable, accelerometer-based surgical navigation system (Knee Align 2 system; Orth Align, Inc, Aliso Viejo, Calif) improve accuracy of the post-operative radiographic femoral component alignment compared to conventional IM alignment guide.

MATERIALS & METHODS

Since February 2014, 44 consecutive patients (39 female, 5 male) with primary arthritis of the knee were enrolled in this prospective, randomized controlled study. 24 patients underwent TKA (Vanguard RP or PS, Biomet Japan) using the navigation device for the distal femoral resection (Navigated Group), and 20 patients with conventional femoral IM alignment guide. The proximal tibial resection was performed using an extramedullary guide. All the operation was performed by a single senior surgeon (YK) with the same gap balancing technique except for the use of the navigation system for the femur. Accuracy of femoral implant positioning was evaluated on 2 weeks postoperative standing anteroposterior (AP) hip to ankle radiographs.

INTRODUCTION

Implantation of total hip arthroplasty (THA) components caused a significant alteration in stress environment. Several studies have reported that bone mineral density (BMD) decreases after THA, especially in the proximal femur. This phenomenon is explained as an adaptive remodeling response of bone tissue to a significant alteration in its stress environment.

SL-PLUS MIA stem (Smith & Nephew Orthopaedics AG) is a modified implant of Zweymuller type SL-PLUS standard stem (Smith & Nephew Orthopaedics AG). The major change is an omission of the trochanteric wing, which enables a bone-sparing and may lead to changes of femoral stress distribution and rotational stability. The change of stress distribution in the femur could affect BMD after THA.

In the present study, we constructed finite element (FE) models of femurs and stems before and at 1week after THA and analyzed equivalent stresses in the femur. In addition, we measured BMD in the femur by dual-energy X-ray absorptiometry (DEXA) after THA. The purpose of this study was to investigate the equivalent stress in the femur and to compare the results of the FE analyses with changes in BMD after THA.

METHODS

Twenty-one patients (18 women and 3 men) who underwent primary cementless THA with SL-PLUS MIA stem or SL-PLUS standard stem formed the basis of this study. Eleven patients received SL-PLUS MIA stem and ten patients received SL-PLUS standard stem. The mean age of the patients at THA was 67 years (range: 48∼82). BMD was measured with DEXA at 1 week and 3, and 6 months after THA. Zones were defined according to Gruen's system (zones 1∼7).

Computed-tomography (CT) images of the femur of all patients were taken before and at 1 week after THA. FE models of the femur and prosthesis were obtained from CT data by Mechanical Finder (Research Center of Computational Mechanics Inc., Tokyo, Japan), software that creates FE models showing individual bone shape and density distribution. Equivalent stresses were analyzed in zones 1 to 7 and compared to the DEXA data.

Background

Data on varus-valgus and rotational profiles can be obtained during navigated total knee arthroplasty (TKA). Such intraoperative kinematic data might provide instructive clinical information for refinement of surgical techniques, as well as information on the anticipated postoperative clinical outcomes. However, few studies have compared intraoperative kinematics and pre- and postoperative clinical outcomes; therefore, the clinical implications of intraoperative kinematics remain unclear.

In clinical practice, subjects with better femorotibial rotation in the flexed position often achieve favorable postoperative range of motion (ROM); however, no objective data have been reported to prove this clinical impression. Hence, the present study aimed to investigate the correlation between intraoperative rotation and pre- and postoperative flexion angles.

Materials and Methods

Twenty-six patients with varus osteoarthritis undergoing navigated posterior-stabilized TKA (Triathlon, Stryker, Mahwah, NJ) were enrolled in this study. An image-free navigation system (Stryker 4.0 image-free computer navigation system; Stryker) was used for the operation. Registration was performed after minimum soft tissue release and osteophyte removal. Then, maximum internal and external rotational stress was manually applied on the knee with maximum extension and 90° flexion by the same surgeon, and the rotational angles were recorded using the navigation system. After knee implantation, the same rotational stress was applied and the rotational angles were recorded again. In addition, ROM was measured before surgery and at 1 month after surgery. The correlation between the amount of pre- and postoperative tibial rotation and ROM was statistically evaluated.

Patients

One hundred and ninety-two consecutive revision total hip arthroplasties were performed with allograft bone supported by the Kerboull or Kerboull type reinforcement acetabular device from 1996 to 2009. There were 23 men and 169 women. Kerboull plates were applied to 18 patients, and Kerboull type plates to 174. The mean follow up of the whole series was 8 years (4–18years).

Surgical Technique

The superior bone defect was reconstructed principally by a large bulky allo block with plate system. Medial bone defect was reconstructed by adequate bone chips and/or sliced bone plates. After temporally fixation of bulky bone block with two 2.0mm K-wires, it was remodeled by reaming to fit the gap between host bone and plate, followed by fixation to the iliac bone by screws. Finally, residual space of the defect between host bone and the fixed plated was filled up with morselized cancellous bones, bone chips, and/or wedged bony fragments with impaction. This method was sufficiently applicable to AAOS Typeâ�, II, and III bone defects. In case of AAOS Typeâ�£, the procedure was also available after repairing discontinuation between distal and proximal bones by reconstrusion plate or allografting with tibial bone plates or sliced femoral head.

Objective

Kinematically aligned total knee arthroplasty (TKA) is of increasing interest because this method may improve patient satisfaction. However, the biomechanics of kinematically aligned TKA remain largely unknown. Therefore, we analyzed whether the kinematic alignment method cause to increase the contact force on patellofemoral and tibiofemoral joints.

Methods

A musculoskeletal computer simulation was used to determine the effects of kinematically or mechanically aligned TKA. Patellofemoral and tibiofemoral contact forces were examined for a mechanically aligned model and a kinematically aligned model using finite element analysis.

Background

Total elbow arthroplasty (TEA) has become an established procedure in the treatment of patients with rheumatoid arthritis (RA). However, there is little information on whether limited extension of the elbow affects clinical outcome scores after TEA and what causes the limited extension.

Methods

We retrospectively analyzed fifty-four cases of primary TEA in patients with RA. There were seven men and thirty-nine women with a mean age of 63.6 years (range, thirty to eighty years). Thirty-seven of Coonrad-Morrey and seventeen of Discovery prostheses were used. The mean length of follow-up was 7.1 ± 4.0 years (range 2.0–14.6 years). Mayo Elbow Performing Score (MEPS) and radiological measurements were recorded. Anteroposterior and lateral radiographs were assessed before and after the operation and at the latest follow-up. Widening of the joint space was calculated by subtracting the length measured on the postoperative radiograph from that on the preoperative radiograph.

Background

Recently the taper wedged stems (TWS) are used widely in Japan because of good bone fixation and ease of the procedure. However, it is unclear how TWS get initial fixation in Japanese, especially dysplasia hip or elderly patients who had stovepipe canal. The purpose of this study is to evaluate initial bone fixation of the TWS in Japanese using computed tomography and to estimate biological bone fixation of the TWS using the Tomosynthesis.

Methods

We evaluated 100 hips underwent primary total hip arthroplasty using TWS. All patients were performed computed tomography within 2 weeks postoperatively and evaluated which part of the canal was made contact with the stem. 24 hips were male and 76 hips were female. According to the canal flare index, 9 hips were champagne flute canal, 80 hips were normal canal and 11 hips were Stovepipe canal. 10 hips were Dorr type A, 80 hips were Dorr type B and 10 hips were Dorr type C.

The initial bone fixation was classified as Medio-lateral fit (fixed at Gruen zone 2 and 7), Flare fit (fixed at zone 2 and 6), Varus 2-point fit (fixed at zone 3 and 7), Valgus 3-point fit (fixed at zone 2, 5 and 7), Distal fit (fixed at zone 3 and 5), Total fit (fixed at zone 2,3,5,6 and 7) by the stem A-P view. Moreover, we defined Medio-lateral fit, Flare fit and Total fit as Adequate fit, Varus 2-point fit and Valgus 3-point fit as Varus or Valgus fit, Distal fit as Distal fit. The stem alignment was classified as flexion, neutral and extension by the stem lateral view.

Femoral component fixation was graded as bone ingrowth, fibrous ingrowth and unstable by hip radiographs after surgery at 1 year. Spot-welds were evaluated using tomosynthesis after surgery at 6 months.

[Purpose]

There have been only a few reports about the efficacy of postoperative cryotherapy following total hip arthroplasty (THA), and past studies have described that local cooling is efficacy for pain relief. The purpose of this study is whether the continuous local cooling following THA is effective for pain relief and the reduction of blood loss, swelling, and the duration of hospital stay.

[Materials and Methods]

Thirty-eight patients (39 hips) underwent primary cementless THA for osteoarthritis and were divided into a cryotherapy group (30 subjects; from Apr. 2013 to Oct. 2013) and a control group (9 subjects; from Nov. 2012 to Mar. 2013). In the cryotherapy group, a continuous cooling pad was applied on the surgical wound and the thigh with a cloth anchor band (CF-3000, Sigmax, Japan) with the cooling temperature set to a constant 5°C for 72 hours immediately after surgery. Blood was collected on postoperative days 1,4,7,14, and 21 to determine Hb, CK, and CRP levels. Postoperative pain of the hip was scored by using a visual analog scale questionnaire on postoperative days 1 to 28. Total doses of selecoxib and dicrofenac sodium used for pain relief were measured. The circumference of patellar superior border was measured on postoperative days 4,7,14, and 28.

The unpaired t-test was used for blood tests as well as for comparisons between the cryotherapy and control groups, and the Mann-Whitney U test was used for the analysis of age, BMI, approach of the surgery, analgesic use, pain scores, the circumference of the thigh and the duration of hospital stay.

[Introduction]

Surgical-site-infections (SSI) prolong hospital stay, and they are leading nosocomial cause of morbidity and a source of excess cost. Recently, a waterless hand-rubbing protocol containing aqueous 1% chlorhexidine gluconate was developed before surgery, but there is no literature in orthopaedic surgery. The aim was to compare the SSI rates between waterless hand-rubbing and traditional hand-scrubbing protocol.

[Materials and Methods]

STUDY 1: A total of 996 consecutive patients who underwent orthopaedic surgery between August 1, 2012 and January 31, 2014, were screened for SSI within 30 days after surgery. 500 patients from August 1, 2012 to April 1, 2013 were used by traditional hand-scrubbing, and 496 patients from June 1, 2013 to January 1, 2014 were by waterless hand-rubbing.

STUDY 2: The twelve operating room staff members were randomly recruited, and the participants were assigned equally to use either a traditional hand-scrubbing protocol or a waterless hand-rubbing on 2 separate days. Washing times were recorded and microorganisms on hands were sampled on bacterial culture plates. Two days after sampling, the grown colonies were counted.

Introduction

Posterior cruciate ligament (PCL) preservation in total knee arthroplasty (TKA) is adovocated on the grounds that it provides better restoration of knee joint kinematics as opposed to PCL sacrifice. Mobile-bearing (MB) total knee prostheses have been in the market for a long time, but the PFC-Sigma Rotating Platform (RP) prosthesis (DePuy Orthopaedics, Inc, Warsaw, Ind) has been introduced in the market since 2000. Since, little is known about the in vivo kinematics of MB prostheses especially with cruciate retaining (CR). The objective of this study is to investigate the in vivo kinematics of MB RP-CR total knee arthroplasty during weight-bearing deep knee bending motion.

Patients and methods

We investigated the in vivo knee kinematics of 20 knees (17 patients) implanted with PFC-Sigma RP-CR. All TKAs were judged clinically successful (Hospital for Special Surgery scores >90), with no ligamentous laxity or pain. Mean patient age at the time of operation was 78.0 ± 6.0 years. Mean period between operation and surveillance was 15.0 ± 9.0 months. Under fluoroscopic surveillance, each patient did a wight-bearing deep knee bending motion. 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 range of motion, axial rotation, and antero-posterior (AP) translation of the nearest point between the femoral and tibial component.

Purpose

The purpose of the present study is to assess 5–10 years' follow-up results after acetabular impaction bone grafting (IBG) in primary cemented total hip arthroplasty (THA) for cases with acetabular bone defect.

Patients and methods

We performed 36 primary cemented THA with acetabular IBG in 33 patients between November 2004 and May 2009. As one patient died due to unrelated disease at 6 months after the surgery, 35 hips of 32 patients were included in this study. The average age at the surgery was 62.4 years, and the average follow-up period was 7.9 years (5–10 years). Diagnoses were osteoarthritis due to acetabular dysplasia in 28 hips (26 patients), Rheumatoid arthritis (RA) in 4 hips (3 patients), rapidly destructive coxopathy (RDC) in 1 hip (1 patient), idiopathic acetabular protrusion in 1 hip (1 patient), and acromegaly in 1 hip (1 patient).

For clinical assessment, the Merle d'Aubigné and Postel hip score was assessed and degree of post-operative improvement was classified according to their method as very great improvement, great improvement, fair improvement, and failure. Perioperative complications were also recorded. Acetabular bone defects were assessed at the surgery and categorized using AAOS acetabular bone defect classification system.

For radiological assessment, anteroposterior radiographs of the bilateral hip joints were analyzed preoperatively and post-operatively. Radiolucent lines (RLL) of more than 2 mm around the acetabular components were assessed using the DeLee and Charnley zone classification. Acetabular component loosening was assessed according to the Hodgkinson et al. classification system, and type 3 (complete demarcation line) and type 4 (migration) were classified as “loosening”.

Introduction

A timely isolation of the causative bacterial species is of paramount importance in the treatment of periprosthetic joint infection (PJI). Sonication of the explanted endoprosthesis and the microbiological culture of sonicate fluid (SFC) has been proven to increase the rate of bacterial isolations in comparison to the conventional microbiological methods. The cultivation of aspired synovial fluid in blood culture bottles (BCB) has been shown to yield a higher rate of bacterial isolations and produce a lower rate of contaminants than cultivation on conventional agar plates. The primary aim of this study was to investigate whether the inoculation of BCB with sonicate fluid leads to a higher rate of bacterial isolations than the culture on agar plates. Secondly, we wanted to investigate whether the utilization of BCB leads to an earlier identification of the causative bacterial species. To our knowledge this is the first study to investigate the effects of BCB use on SFC.

Methods

We performed a retrospective analysis comparing the results of the two different culture methods. To detect slow growing species all microbiological cultures, regardless of the culture method, were incubated for 14 days.

Background

Acetabular cup malpositioning during total hip arthroplasty (THA) is known to lead to impingement, instability, wear-induced osteolysis, and increased rates of revision surgery. The purpose of this study was to independently evaluate the accuracy of acetabular cup orientation using a novel mechanical navigation device.

Methods

Postoperative acetabular cup orientation was reviewed in 47 primary THAs using the HipSextant mechanical navigation device. Angles were measured with a validated two-dimensional/three-dimensional matching application. An outlier was defined as +/− 10 degrees outside of the preoperative plan for inclination and anteversion.

Introduction

Ceramic composites have been developed to further improve the mechanical properties, reduce risk of fracture, and increase the survivorship of ceramic-on-ceramic bearings in total hip replacement¹.

The aim of this study was to evaluate the wear of two novel ceramic composite materials under edge loading conditions due to translational mal-positioning when used in both like-on-like and mixed pairing configurations; and to compare their performance to earlier generation ceramic-on-ceramic bearings.

Materials and Methods

The head-on-cup configurations of three ceramic materials (see Figure 1), were ATZ-on-ATZ, ZTA-on-ZTA, Al₂O₃-on-Al₂O₃, ATZ-on-ZTA, ZTA-on-ATZ, Al₂O₃-on-ATZ, ATZ-on-Al₂O₃and Al₂O₃-on-ZTA. All combinations were size 28mm and were supplied by Mathys Orthopädie GmbH (Morsdorf, Germany). They were tested for four million cycles on the Leeds II hip simulator under microseparation^2,3,4 conditions representing translational mal-positioning. The gait cycle comprised extension/flexion (−15º/+30º), internal external rotation (+/−10º) and a twin peak load with a maximum of 3kN. Microseparation was achieved by applying a 0.5mm dynamic medial/lateral displacement using a spring load resulting in edge loading at heel strike. New-born calf serum (25%) was used as a lubricant. Wear was assessed gravimetrically every million cycles. Statistical analysis was performed using one-way ANOVA (significance taken at p<0.05).

Introduction

Increased wear rates [1, 2] and acetabular rim fracture [3] of hip replacement bearings reported clinically have been associated with edge loading, which could occur due to rotational and/or translational mal-positioning [4]. Surgical mal-positioning can lead to dynamic microseparation mechanisms resulting in edge loading conditions. In vitro microseparation conditions have replicated stripe wear and the bi-modal wear debris distribution observed clinically [5, 6]. The aim of this study was to investigate the effect of steep cup inclination, representing rotational mal-positioning, on the magnitude of dynamic microseparation, severity of edge loading, and the resulting wear rate of a ceramic-on-ceramic bearing, under surgical translational mal-positioning conditions.

Materials and Methods

Ceramic-on-ceramic bearings where the ceramic liner was inserted into a titanium alloy cup (BIOLOX® delta and Pinnacle® respectively, DePuy Synthes, UK) were tested on the six-station Leeds II hip simulator. The first test was run with the cups inclined at an angle equivalent, clinically, to 45° (n=6) and the second test was run with the cups inclined at an angle equivalent, clinically, to 65° (n=6). A standard gait cycle was run. A fixed surgical translational mal-positioning of 4mm between the centres of rotations of the head and the cup in the medial/lateral axis was applied on all stations. Both tests ran for three million cycles each. The lubricant used was 25% new-born calf serum. Wear was assessed gravimetrically using a microbalance (XP205, Mettler Toledo, UK) and geometrically using a coordinate measuring machine (CMM, Legex 322, Mitutoyo, UK). Statistical analysis was done using one way ANOVA with significance taken at p<0.05.

Introduction

Wear debris induced osteolysis and loosening continue to cause clinical failure in total knee replacement (TKR). To improve longevity and reduce wear alternative materials have been examined. Carbon-fibre-reinforced poly–ether-ether-ketone (CFR-PEEK) has shown promising results in wear studies [1–2].

The aim of this study was to explore the use of CFR-PEEK and PEEK as alternative bearing materials for polyethylene in TKR through experimental knee joint wear simulation.

Methods

Two novel materials were studied as an alternative to polyethylene as the tibial bearing surface in a TKR configuration using a Cobalt chrome femoral bearing in current clinical use. Six right Sigma CR fixed bearing TKRs (DePuy Synthes, UK) were paired with either PEEK or CFR-PEEK custom-made flat inserts (Invibio, UK) in a Prosim knee simulator (Simulator Solutions, UK). The tibial inserts were 14mm thick, to give an equivalent thickness to existing insert designs. A flat geometry was selected as this has previously been shown to yield low wear in polyethylene bearings [3]. The tests were conducted under High Kinematics, with anterior-posterior and internal-external displacement control [4]. Tests were conducted for three million cycles, lubricated with 25% bovine serum, with wear assessed gravimetrically at 1 and 3Mc.

Images of the wear scars were recorded at completion of the study. Visual inspection of the tibial inserts was used to identify regions of wear damage for SEM analysis (EVO MA15-Smart SEM, Zeiss, Germany)

Objectives

An optimal reconstruction of the joint anatomy and physiology during revision total knee replacement (RTKR) is technically demanding. The standard navigation systems were developed for primary procedures, and their adaptation to RTKR is difficult. We present a new navigation software dedicated to RTKR. The rationale of this new software was to allow a virtual planning of the joint reconstruction just after removal of the primary prosthesis.

Methods

The new software was developed on the basis of a non-image based navigation system which has been extensively validated for implantation of a primary TKR. Following changes have been implemented: 1) to define and control the vertical level of the joint space on both tibia and femoral side; 2) to measure the tibio-femoral gaps independently in flexion et en extension on both medial and lateral tibio-femoral joints; 3) to virtually plan and control the vertical level and the orientation of the tibia component; 4) to virtually plan and control the sizing and the 3D positioning of the femoral component (figure 1); 5) to virtually plan and control the potential bone resection; 6) to virtually plan and control the potential bone defects and their reconstruction (bone graft or augments) (figure 2); 7) to virtually plan and control the size, the length and the orientation of the stems extensions independently on the femoral and on the tibia side (figure 3).

The validity of the concept has been tested by 20 patients operated on for RTKR for any reason, with a routine reconstruction with a cemented, unconstrained revision implant. The accuracy of the experimental software was assessed 1) during the procedure after implantation of the RTKR by measuring the medial and lateral laxity in full extension and 90° of knee flexion with the navigation system, and 2) on post-operative radiographs.

Objectives

How to position a unicompartmental knee replacement (UKR) remains a matter of debate. We suggest an original technique based on the intra-operative anatomic and dynamic analysis of the operated knee by a navigation system, with a patient-specific reconstruction by the UKR. The goal of the current study was to assess the feasibility of the new technique and its potential pitfalls.

Methods

100 patients were consecutively operated on by implantation of a UKR with help of a well validated, non-image based navigation system, by one single surgeon. There were 41 men and 59 women, with a mean age of 68 years (range, 51 to 82 years). After data registration, the navigation system provided the dynamic measurement of the coronal tibio-femoral mechanical angle in full extension. The reducibility of the deformation was assessed by a manually applied torque in the valgus direction. The patient-specific analysis was based on the following hypotheses: 1) The normal medial laxity in full extension is 2° (after previous studies), 2) there was no abnormal medial laxity (which may be routinely accepted for varus knees) and 3) the total reducibility is the sum of the patient's own medial laxity and of the bone and cartilage loss. We assumed that the optimal correction may be calculated by the angle of maximal reducibility, less 2° to respect the normal medial laxity. The bone resections were performed accordingly to this calculated goal. No ligamentous balance or retension was performed. The fine tuning of the remaining laxity was performed by adapting the height of polyethylene component with a 1 mm step. The final measurements (coronal tibio-femoral angle in full extension and medial laxity in full extension) were performed with the navigation system after the final components fixation. The implantation had to fulfill these two parameters: optimal correction as defined previously, and a 2 ± 1° of medial laxity.

Objectives

The goal of this retrospective study was to compare two different processes of pain control after total knee arthroplasty (TKA): local anesthesia versus femoral nerve block. The tested hypothesis was that the patient's ability to be discharged was obtained sooner with the local anesthesia process.

Methods

110 patients consecutively operated on for TKA by a single surgeon without any selection criterion were included. The study group included 58 patients operated on under general anesthesia with infiltration of the surgical field with local anesthesia. The control group included 52 patients operated on under general anesthesia and continuous femoral nerve block. In the study group, 200 ml of ropivacaïne 5% were injected into the surgical field, and an intra-articular catheter was left to allow continuous infusion of ropivacaïne (20 ml/h during 24 hours). The control group was treated by a femoral nerve block with ropivacaïne during 24 hours. Discharge was considered allowed when the patient was able to walk independently, go upstairs and downstairs independently, when the knee flexed over 90° and if the subjective pain assessment (VAS) was under 3/10.

Objectives

The appropriate treatment for chronically infected TKR is controversial. One-stage exchange is believed to be possible only in selected cases, but the respective indications and contra-indications and the criteria of selection are not fully validated. We wanted to test the relevance of the commonly used selection criteria by comparing two groups of patients: the control group operated on with a routine one-stage exchange without selection criteria, and the study group operated on by one stage exchange on selected patients only. We hypothesized that selected one-stage exchange gives fewer failures than routine one-stage exchange procedure.

Methods

We performed a retrospective study of 108 cases selected in a database of 600 patients with an infected total knee arthroplasty. The database resulted from a French multicenter trial of specialized surgeons in reference institutions, including all consecutive cases operated on between 2000 and 2010. There were 64 women and 44 men with a mean age of 69 years. All patients were followed-up for a minimal period of two years or when septic failure occurred. The patients were divided into two groups: patients operated on in a center using a routine one-stage exchange policy, and patients operated on in a center using a selected one-stage exchange policy. Patients were matched in the two groups according to body mass index and the aspect of the wound at the initial examination (one scar, several scars, presence of a fistula). The results were expressed as: free of infection, relapse or persistence of the index infection, occurrence of a new infection. The repartition was compared in the two groups by a Chi² test at a 0.05 level of significance. The cumulative survivorship was plotted with infection recurrence for any reason as the end point.

Purpose

The purposes of this study are as follows; 1) to compare postoperative blood loss between general anesthesia(GA) and spinal anesthesia(SA) and 2) to analyze the affecting factors of postoperative blood loss through the subgroup analysis.

METHODS

A retrospective analysis was made on the clinical data of 122 patients with osteoarthritis undergoing primary TKA between January 2012 and December 2013. According to different anesthetic method, the patients were divided into the General Anesthesia group (73 cases) and the Spinal Anesthesia group (49 cases). Each group was divided subgroup as age, BMI, Preoperative blood pressure, Surgery time, Torniquet time, INR. The total blood loss, Post Operation 1 day blood loss, hidden blood loss, and the percentage of hidden blood loss were compared between 2 groups. For the analysis of postoperative blood loss, each group was compared postoperative blood loss using hemovac drainage per day and total blood loss. In preoperative blood pressure, Higher than 140 mmHg in systolic blood pressure and higher than 90 mmHg in diastolic blood pressure were employed as a cut-off value to group the well-controlled hypertension group(n=42) and uncontrolled hypertension group(n=29)

Introduction

Incorrect restoration of the joint line during total knee arthroplasty (TKA) can result in joint instability, anterior knee pain, limited range of motion, and joint stiffness. Although restoration of the correct joint line (i.e., creating an optimal gap in extension and flexion) should be considered in all TKA procedures, no surgical techniques have been established for restoring it. We performed the femoral posterior condylar precut technique (Kaneyama R. Bone Joint Res. 2014; 3) in 91 TKA cases and evaluated the joint line by measuring the thickness of the surgically removed femoral bone and femoral components.

Methods

A total of 91 knees in 73 patients who underwent primary TKA between June and December 2013 were reviewed retrospectively. The posterior cruciate ligament was preserved in all patients. First, in the femoral posterior condylar precut technique, the extension gap was created by the measured resection technique. Then we created a temporary gap in flexion 4 mm smaller than that created by the measured resection technique and remove posterior osteophytes and soft tissue for good ligament balance. Once the component gap was determined, final femoral posterior condyle cutting was performed to create an optimal gap and rotation. We evaluated the joint line from the differences in thickness between the surgically removed femoral bone and femoral components, and revised the thickness of the bone saw accordingly. The value was positive when the joint line had been raised and negative when it had been lowered.

INTRODUCTION

Rotational alignment of the femoral and tibial component in total knee arthroplasty (TKA) are separately determined based on the anatomy of each bone. Popular references are the transepicondylar axis (TEA) for femoral component, and medial one-third of the tibial tubercle for the tibial component. It was reported that these references are not in accordance with each other in osteoarthritic (OA) knees and rotational mismatch could occur even when the components were accurately aligned. There has been, however, a paucity of data as for the rotational mismatch after TKA for OA knees. The purpose of this study was to evaluate the rotational mismatch between the femoral and tibial component after TKA for OA knees.

SUBJECTS & METHODS

Eighty-four knees which underwent primary TKA for the varus osteoarthritis of the knee were analyzed. Those knees were chosen by the retrospective confirmation of the precise rotational alignments of both femoral and tibial components by postoperative computed tomography (with ±3 degrees to the targeted reference lines described below). The femoral reference line was the surgical epicondylar axis and the tibial reference line was Akagi's line; a line connecting the midpoint of the tibial insertion of the posterior cruciate ligament and the medial border of patellar tendon. Intraoperative, dynamic evaluations of the rotational mismatch between femoral and tibial components was performed with a special device attached to the mobile-bearing trials at full extension and in neutral, passive external rotation and passive internal rotation.

Introduction

Total hip arthroplasty is considered to be one of the most successful orthopaedic interventions. Acetabular component positioning has been shown to affect dislocation rates, component impingement, bearing surface wear rates, and need for revision surgery. The safe zones of acetabular component positioning have previously been described by Lewinnek et al. as 5 to 25 degrees of cup version and 30 to 50 degrees of inclination. Callanan et al. later modified the inclination to 30 to 45 degrees. Our aim was to assess whether THA via robotic assisted posterior approach (PA) improves acetabular component positioning compared to fluoroscopic guided anterior approach THA (AA).

Methods

OBJECTIVE

The purpose of this study was to investigate the postoperative change of hematological values between post cam type posterior stabilized (PS) and deep dish cruciate substituting (CS) type total knee arthroplasty (TKA).

MATERIALS AND METHODS

From June 1999 to December 2013, 322 patients with TKA due to osteoarthritis or rheumatoid arthritis were enrolled. In all knees, posterior cruciate ligament (PCL) were resected, and either Scorpio NRG PS knee (Stryker Orthopaedics) or Triathlon CS knee (Stryker Orthopaedics) were implanted. The PS group included 183 patients (183 knees) consisting of 4 men (4 knees) and 179 women (179 knees) with a mean age of 68.5 years (range 31 – 86 years). And the CS group included 139 patients (139 knees) consisting of 27 men (27 knees) and 112 women (112 knees) with a mean age of 75 years (range 42 – 98 years). Simultaneous bilateral TKA were excluded in this study. No case had blood transfusion in perioperative period. The changes of hemoglobin (Hb), d-dimer (DD) and c-reactive protein (CRP) were compared at pre-operative value, 1, 4, 7 and 14 days after surgery in two groups.

Background

Polymethylmethacrylate (PMMA) has been used for total knee arthroplasty (TKA) as a method of fixation; however, its durability has been questionable for the long-term use because of the loosening after the cement deterioration, its vulnerability toward infectious resistance, and a smaller amount of healthy bone left for the knee revision surgery. Especially, a decrease of bone density on the proximal tibia has been believed to be triggered as a result of stress shielding. When compared with a cemented TKA, a cementless TKA reduces the amount of bone loss after surgery. In 1999, the Trabecular Metal (TM), with its main composition being the porous tantalum metal, became available as a choice of the porous cementless knee joint prosthesis. The characteristics of porous tantalum metal are its great affinity to the bone as well as its similarity to cancellous bone. The porous tantalum metal starts to bond with osteoblasts, and fills up 80% of porous structure in one year; therefore, it has been characterized by its higher initial fixation strength. However, it is questionable if strong fixation strength due to bone ingrowth between the tibial tray mainly made up with the porous tantalum metal and a cancellous bone will continually be kept. Bobyn, JD, Dunbar et al. have acknowledged the existence of bone ingrowth based on the radiographic evaluation; however, their data had not been quantified in their report. In this study, the bone ingrowth density have periodically quantified using 3D bone morphometric software (TRI/3D-BON64.RATOC) after taking CT of the knee joint prosthesis.

Material and Methods

From October 2011, we have reviewed 45 medial osteoarthritis knees that underwent MIS-TKA using Trabecular Metal Modular Tibia CR-type (Zimmer, Inc, Warsaw, Indiana). Ages range from 61–89 years (mean, 74.5 years), and 5 males (7 knees), and 32 females (38 knees) participated in this study. After taking CT picture with the Phantom under lower extremities, the bone ingrowth density are quantified utilizing 3D bone morphometric software (TRI/3D-BON63.RATOX). Measured areas are divided into 6 zones that are right under the pegs of TM femoral component, and the bone ingrowth density (BMC/TC) between TM and cancellous bone were periodically measured on 3, 6, 9, 12,15,18,21,24.27 months after the surgery. Also, intra-zone comparison were implemented by each period among Medial (Zone 1), Lateral (Zone 2), Medial Anterior (Zone 3), Medial Posterior (Zone 4), Lateral Anterior (Zone 5), and Lateral Posterior (Zone 6). Mann-Whitney U test and Student's t-test were used for statistical analysis. All cases of tibial component alignment was within 3 degree varus-valgus to neutral alignment.

Introduction

A small medial extension gap (EG) needs posterior soft tissue release to avoid undesirable additional resection of the distal femur in total knee arthroplasty (TKA). However, the effect of this procedure on the EG is not always sufficient because the EG is influenced not only by the posterior soft tissue but also by the medial collateral ligament (MCL). We hypothesize that contracture of the posterior capsule prevents full elongation of the MCL in extension and we investigated the efficacy of posteromedial vertical capsulotomy (PMVC) on the medial EG which separate MCL from the posterior capsule (Fig. 1).

Materials and Methods

The PMVC was performed on 128 knees in which the medial extension gap was considered too small. The EG was initially created with a standard femoral distal cut and tibial cut. To estimate the gaps more precisely before flexion gap (FG) adjustment at the final step of the surgery, we performed a 4 mm precut of the posterior femoral condyle and measured the gaps with the patella reduced after setting a precut trial component that had a usual distal part and 4 mm thick posterior part of the femoral component. This situation was the same as after setting the usual femoral trial component by using the measured resection technique with preservation of the posterior cruciate ligament (PCL) (Fig. 2). The semimembranosus tendon was not released in any cases.

Purpose

The best care paradigm for the older patient with proximal humeral fracture/dislocation is typically hemiarthroplasty, yet post-operative instability and suboptimal functional outcomes are commonplace. The aim of this study was to compare innovative treatment strategies designed to improve outcomes including: hemiarthroplasty combined with capsulolabral repair versus reverse total shoulder arthroplasty.

Methods

After IRB approval, analysis was performed on patients treated with arthroplasty for proximal humeral fracture/dislocation. Functional results and evidence of complication including instability (subluxation, dislocation) was determined. rTSA and hemiarthroplasty with capsulolabral repair were compared to hemiarthroplasy alone (control group).

Purpose

Posterior pelvis tilt (PPT) would affect lumbar lordosis and lead to hip flexion, which causes difficulties walking and standing in patients with hip disorders. Hip flexion movement associated with PPT is well known. We investigated the effect of the angle of hip flexion without the movement of PPT in the supine position.

Methods

The study enrolled 24 healthy males with an average age of 20.5 ± 2.3 years. Two pelvic positions in the supine position were investigated: (1) the limited position of the PPT by 500ml PET bottle with water placed under their low back, and (2) the position without placing a PET bottle. We assessed unilateral hip flexion angle with photos taken with a digital camera. For reference, we took an X-ray of a healthy female and observed the lumbo-sacral from the sagittal plane in the supine position.

Introduction

Patients undergoing total hip arthroplasty (THA) stand in the danger, a particularly high risk for venous thromboembolism (VTE). Fondaparinux and edoxaban, which inhibit FXa, indirectly and directly, respectively, have been used for prevention of VTE after THA in Japan. The aim of this study was to compare the efficacy of fondaparinux and edoxaban for VTE after elective THA in Japanese patients.

Materials and methods

We randomly assigned 320 patients underdoing elective cemented THA to receive postoperative 2.5 mg fondaparinux once daily for first postoperative 3 days and 1.5 mg once daily for the subsequent 7 days (FPX group) [1], postoperative 15 mg edoxaban once daily for postoperative 10 days (EDO15mg group), 30 mg edoxaban once daily for postoperative 10 days (EDO30mg group), and 30 mg edoxaban once daily for first postoperative 3 days and 15 mg once daily for the subsequent 7 days (EDOmix group). Deep venous thrombosis (DVT) was diagnosed by ultrasonography at postoperative day 3 and 14. Computed tomography to detect pulmonary thromboembolism was performed to all patients who had proximal DVTs. The χ² test with Bonferroni correction was used to compare variables of the incidence of DVT between each group. The intention-to-treat analysis was performed for statistical analysis in each group. The EDO30 mg group and EDOmix group were regarded as one group in the assessment at the postoperative day 3, and named as the EDO30mg+mix group.

Background

Variability in component alignment continues to be a major in total knee arthroplasty(TKA). In the long term, coronal plane malalignment has been associated with an increased risk of loosening, insatability, and wear. Recently, patient specific guide in total knee arthroplasty have been introduced, in which preoperative 3-dementional imaging is used to manufacture disposable cutting guide specific to a patient's anatomy. The goals of patient specific guide are to improve the accuracy of post operative alignment and eliminate outlier cases. The aim of this study is to evaluate clinical results and quantify the coronal plane alignment between a group of patients who underwent TKA using patient specific guide versus standard instrumentation.

Patients and Method: An unselected consecutive series of seventy patients undergoing primary TKA using the same cruciate retaining cemented total knee system (Vanuard^TM, Biomet, Inc, warsaw, Indiana USA) between April 2010 and September 2013 were studied. Patients were included only if they were deemed to be candidates for a

Cruciate retaining TKA. Patients were excluded if they had a flexion contracture greater than 40°, or severe valgus or varus deformity. Forty-nine knees was operated a TKA with standard instrumentation method. Subsequently twenty-one knees was received a TKA using CT-based patient specific guide(Signature^TM). Postoperatively standing AP hip-to-ankle radiographs were obtained, from which the lower extremity mechanical axis, component angle were measured. The alignment goals were a neutral mechanical axis defined as a hip-to-ankle angle of 0°with the femoral and tibial components aligned perpendicular to the mechanical axis. The total operating time were quantified utilising an operating room database. The total operating time between TKAs performed with standard instrumentation and those performed with patient specific guides was compared in each group. All patients postoperatively was evaluated of clinical results the Japan Orthopedics Association(JOA) Knee scores. Postoperative blood loss volume and postoperative concentrations of D-dimer were also measured.

Results

The mechanical axis angle in patient specific guide group was 1.8°, while the standard instrumentation group was 3.4°and there was no statistical significance. The number of outliers for mechanical axis angle was virtually identical between patient specific guide group 29.0% and the standard group 38.8%. The components angle between the two groups did not achieve statistical significance. The operative time in patient specific guide was 117.4 minutes and significantly less compared to the time of standard group 130.4 minutes. The JOA Knee score of standard instrumentation group was 80.8 points, and the score of patient specific guides group was 85.7 points. There was no statistical significance between the two groups on the clinical score. The blood loss volume of between the two group was no different substantially. The postoperative concentrations of D-dimer of patient specific guide group was 5.3(μg/ml), more less significantly than standard group 9.2 (μg/ml).

Introduction

Female gender, old age (men >60y and women > 55y), severe acetabular dysplasia, poor proximal femoral bone geometry, large (>1cm) femoral head cysts, limb-length discrepancy (> 2cm) and small prosthetic head size (less than 50mm for men and less than 46mm for women) are risk factors for hip resurfacing arthroplasty (HRA).

Purpose

To present clinical and radiographic results of HRA in patients having risk factors.

Patients and methods: A total of 39 HRA was inserted in 33 patients (11 men and 22 women). Birmingham hip resurfacing (Smith & Nephew, UK) was used in 9 hips and Adept (Finsbury, UK) was used in 30 hips. Among the 30 hips inserted Adept, 11 cups were fixed with rim screws. The mean age of the patients at the time of operation was 52 years. The mean weight and height of the male and female patients were 70.4kg and 167cm, 58.5kg and 154.4cm, respectively. The median head size of the male and female patients was 50mm and 42mm, respectively. Preoperative diagnosis was primary osteoarthritis in 6 hips and secondary osteoarthritis due to aceatbular dysplasia (DDH) in 33 hips. Risk factors of HRA were listed for each patient. The Harris hip score and visual analogue pain scale (VAS) were measures of clinical outcome. Radiographic review was performed retrospectively. MRI and CT images were acquired in 29 hips and 2 hips, respectively, at a mean of 4.8 years after HRA to find periprosthetic soft tissue abnormality such as a psedotumor. Kaplan-Meier method was used to calculate implant survivorship.

Introduction

Highly cross-linked polyethylene (HXLPE) was developed to reduce the wear of articular-bearing surfaces in total hip arthroplasty (THA). This study aimed to compare the mean linear wear of HXLPE with a 22.225 mm diameter zirconia head with that of conventional polyethylene (CPE) with a 22.225 mm diameter ortron head.

Materials and Methods

A prospective cohort study performed on 93 patients (113 hips) who had undergone primary cemented THAs at our hospital between January 2001 and December 2003. The subject population included 85 females and 8 males with a mean age of 58.0 years (22 to 78) at the time of surgery. The mean follow-up period was 10.2 years (9 to 12). We randomly used two types of implants: the HXLPE cup with a 22.225 mm diameter zirconia head (Kyocera Medical, Osaka, Japan) in 60 hips (HXLPE group), and the CPE cup with a 22.225 mm diameter ortron head (DePuy International, Leeds, UK) in 53 hips (CPE group). Linear wear (penatration) by computer-assisted method with PolyWare software (Draftware Inc, Indiana, USA) was measured at 10 years. Anteroposterior radiographs were evaluated for osteolysis or component loosening defined by the criteria of Hodgkinson et al. Analysis of covariance using the general linear models procedure was carried out to determine the linear wear rate difference between the groups after adjusting for variables (age at surgery, sex, body mass index, vertical distance, horizontal distance, cup inclination, and cup anteversion) as covariates. The differences were considered significant when the p value was <0.05.

Introduction

To utilize existing cancellous bone for initial stability, custom-made stems were implanted without reaming and rasping. This study reviewed the results of this non-reaming technique.

Methods

One hundred and fifty-three hips (138 patients) were followed-up for an average of 12 years (range, 8 to 18). Average age at the surgery was 59 (range, 19 to 78). Seventy percent of the etiologies were dysplastic hips including 17 hips after femoral osteotomy. The Ti-6Al-4V stems were designed using CT data and directly inserted into the femora without reaming and rasping. The stems were coated with hydroxyapatite on the porous coating at proximal 1/3. Harris hip score was used for clinical evaluation.

Introduction

Proximal humeral fracture occurs most frequently in elderly and usually unite within 12 weeks. Malunion is more common than nonunion. And even if nonunion occurs, we usually treat it by the blade plate. Norris et al. reported hemiarthroplasty is indicated for severe degenerative changes of the articular surface, osteonecrosis of the humeral head, or osteopenia severe enough to jeopardize fixation in order patients. Therefore, it is not common that hemiarthroplasty is used for primary treatment of the proximal humeral pseudoarthrosis. We report a case of proximal humerus pseudoarthrosis which was treated by hemiarthroplasty.

Case

A patients is 75 years old male. He was injured by falling from ladder. He was diagnosed proximal humeral fracture Neer type2. After he was followed conservatively for one year, he was referred to our hospital. In X-ray film and CT, the humeral head was scraped by the humeral shaft that was tucked inward to humeral head.(Figure 1) In MRI, rotator cuff muscles were left. The fatty infiltration was stage 1 in the Gourtallier classification. (Figure 2)And osteoarthritis of shoulder was not so severe. Therefore, we decided to do hemiarthroplasty. We used the SMR implant (Lima Corporate, Milano, Italy). Surgical reconstruction was done using a deltpectral approach. Lesser tuberosity was cut from greater tuberosity with subscaplaris muscle. We used the cementless stem. Each fragments and stem was fixed using FiberWire (Arthrex, Florida USA), after autograft which scraped from the reseceted humeral head was stuffed. After the operation, the shoulder was fixed by brace for 4weeks. The passive ROM exercise was started from 21 days later. The Active ROM exercise was started at 28 days later. Three months later, the pseudoarthrosis united successfully. (Figure 3) The active flexion was improved from 20 degrees to 110 degrees. The active abduction was from 20 degrees to 90 degrees. USLA score was improved from 10 to 26.

Introduction

A full 3D postoperative analysis, i.e. a quantitative comparison between planned and postoperative positions of bone(s) and implant(s) in 3D, is necessary for a thorough assessment of the outcome of the surgery, as well as to provide information that could be used to optimize similar procedures in the future. In this work, we present a method of postoperative analysis based on a pair of X-ray images only, which reaches a level of accuracy that is comparable with the results obtained with a 3D postoperative image.

Methods

The method consists in using 3D models of bones, segmented from 3D preoperative image (e.g. CT or MRI scans), and 3D models of implant, and aligning them independently to X-rays by matching contours manually drawn on the X-rays and projected contours. The result gives the relative postoperative position of bone and implant. The method was tested on a phantom consisting of commonly available femoral knee implant on a physical model of a femur (Sawbones®). Result was compared to the optical scan, considered as ground truth, of the implanted saw bone. Two studies were performed: inter-operator (six operators), and intra-operator (5 tests). In addition, the inter-operator study was repeated while asking all the operators to use the same pre-drawn contours. The results are presented by calculating the distance (anterior/posterior, proximal/distal, medial/lateral) between the centers of gravity, and the angles (varus/valgus, flexion/extension, external/internal rotations) of the implants from the X-ray based method and the ground truth.

Results were also compared with the relative position of bone and implant extracted from a 3D CT postoperative image. Saw bone and implant were first segmented from this image. In order to determine the position of the implant, despite the metal artefacts in the CT images, the 3D model of the implant was registered on the segmented implant.

All processing, including segmentation, registration of X-rays, and measurements, was performed using Mimics Innovation Suite 17.0 ®.

Purpose

The purpose of this study was to compare the clinical and radiological results after total knee arthroplasty(TKA) with PCL sacrificing (PCS) Medial Pivot Knee (MPK) and PCL Substituting (PS) Nexgen® LPS.

Materials and Methods

One hundred twenty knees in 80 patients after TKA with PCS ADVANCE® MPK (Group I) and 116 knees in 85 patients with PS Nexgen® LPS (Group II) were retrospectively evaluated. All the patients were followed up for more than 6 years. The evaluations included preoperative and postoperative range of motion (ROM), tibiofemoral angle, Knee Society (KS) knee and function score, Hospital for Special Surgery (HSS) knee score, WOMAC score and postoperative complications.

Purpose

The purpose of this study is to analyse regional differences in the microstructural and mechanical properties of the distal femur depending on osteoarthritic changes using micro-images based on finite element analysis.

Materials and Methods

Distal femur specimens were obtained from ten donors composed of 10 women with OA (mean age of 65 years, ranging from 53 to 79). As controls, the normal distal femur was sampled from age and gender matched donors consisting of 10 women(mean age of 67 years, ranging from 58 to 81). The areas of interest were six regions of the condyles of the femur(Lateral-Anterior, Middle, Posterior; Medial=Anterior, Middle, Posterior). A total of 20 specimens were scanned using the micro-CT system. Micro-CT images were converted to micro-finite element model using the mesh technique, and micro-finite element analysis was then performed for assessment of the mechanical properties.

Introduction

Revision TKA can be a difficult and complex procedure. Bone quality is commonly compromised and stem fixation is required in many cases to provide stability of the prosthetic construct. However, utilization of diaphyseal engaging stems adds complexity to the case and can present technical challenges to the surgeon. Press fit metaphyseal sleeves can provide stable fixation of the construct without the need for stems and allows for biologic ingrowth of the prosthesis. Metaphyseal sleeves simplify the revision procedure by avoiding the need to prepare the diaphysis for stems, alleviating the need for offset stems and decreasing the risk of intra-operative complications. The ability to obtain biologic fixation in the young patient is also appealing. This study reports on the author's mid-term experience with this novel technique.

Methods

Between May 2007 and June 2009 the author performed 17 revisions TKA that utilized press-fit metaphyseal sleeves without stems on either the tibial side of the joint, the femoral side of the joint or both. Twenty six sleeves were implanted altogether (13 tibial, 13 femoral). Patients were limited to touch down weight bearing for 6 weeks post-operatively. The patients were followed prospectively with clinical and radiographic follow-up at routine intervals.

Introduction

Kinematics analyses of the spine have been recognized as an effective method for functional analysis of the spine. CT is suitable for obtaining bony geometry of the vertebrae but radiation is a clinical concern. MRI is noninvasive but it is difficult to detect bone edges especially at endplates and processes where soft tissues attach. Kinematics analyses require tracking of solid bodies; therefore, bony geometry is not always necessary for kinematics analysis of the spine. This study aimed to develop a reliable and robust method for kinematics analysis of the spine using an innovative MRI-based 3D bone-marrow model.

Materials and Methods

This IRB-approved study recruited 17 patients undergoing lumbar decompression surgery to treat a single-level symptomatic herniation as part of a clinical trial for a new dynamic stabilization device. T1 & T2 sagittal MRI scans were acquired as part of the pre-operative evaluation in three positions: supine and with the shoulders rotated 45° to the left and right to induce torsion of the lumbar spine. 3D bone-marrow models of L5 and S1 at the neutral and rotated positions were created by selecting a threshold level of the bone-marrow intensity at bone-marrow/bone interface. Validated 3D-3D registration techniques were used to track movements of L5 and S1. Segmental movements at L5/S1 during torsion were calculated.

Introduction

Ceramic total knee arthroplasty (TKA) was introduced as a new-generation of knee prostheses in clinical practice, and are expected to reduce polyethylene wear due to its resistance to abrasion and lubrication. In 1992, we developed a cruciate retaining LFA-I total knee prosthesis (KYOCERA Medical Co., Japan), which comprises an alumina ceramic femoral component and a titanium-alloy tibial component with a polyethylene insert. The purpose of this study was to evaluate clinical results in rheumatoid patients who were treated with the alumina-ceramic LFA-I prosthesis with a minimum 15-year follow-up period.

Methods

A total of 70 primary TKAs were performed in 51 patients between 1993 and 1996 using the cemented alumina-ceramic LFA-I prosthesis. Sixteen of these patients (20 knees) had died by the time of this study, of causes unrelated to the index arthroplasty, and 11 patients (16 knees) were lost to the follow-up. The remaining 34 knees were clinically and radiographically evaluated in the present study. The average follow-up time was 16.7 years. The average age of the patients was 58.2 years at the time of the operation. The clinical assessment was conducted with the Hospital for Special Surgery Knee rating score and the Knee Society scoring system. The component alignment and bone-implant interface were evaluated according to the Knee Society Roentgenographic Evaluation System.

Purpose

To update current surgical management of knee osteoarthritis.

Methods

A literature review was done using standard keyword search. Articles were scrutinized by the investigators to ensure relevancy to the purpose of this review.

Purpose

To update recent findings about the relationship between obesity and post-operative outcome including acetabular cup positioning, complications, readmissions and revision rates, and also inpatient rehabilitation outcome following total hip arthroplasty.

Methods

A literature review was done using standard keyword search. Articles were scrutinized by the investigators to ensure relevancy to the purpose of this review.

Introduction

Total knee arthroprasty (TKA) is an excellent treatment with osteoarthritis of the knee joint. The acquisition of joint stability after TKA is one of the most important factors to improve the patient's quality of life. Deep flexion of knee joint is often demanded in daily life, and stability in flexed knee position is also important. But there were few papers reporting about laxity in flexed knee position. This study aimed to analyze influence of pre-operative alignment on post-operative varus-valgus joint laxity in TKA. We investigated the varus-valgus laxity of knee joint throughout flexion intra-operatively before and after prosthetic implantation.

Methods

A total of 20 knees underwent TKA using posterior-stabilised (PS) type component by the measured resection method were included in this study. The varus-valgus joint laxity of knee was measured using an intra-operative navigation system at every 10 ° throughout the range of movement under general anesthesia. We examined the correlations between the pre-operative femorotibial angle (FTA) and varus-valgus joint laxity by method of least squeres. We divided the patients group into two populations according to pre-operative FTA. Large FTA group had more than or equal to 186 °of pre-operative FTA. Small FTA group had less than 186 °pre-operative FTA. T- test was performed between those populations.

Introduction

Wear of the UHMWPE tibial component remains a major reason for aseptic loosening and subsequent revision or failure of TKAs [1]. Many retrieval studies measure surface damage patterns as surrogates for the severity of wear, but little is known about how these patterns relate to the volume of material lost. This study (a) examines the wear rate of a cruciate retaining TKA design and (b) relates observed wear patterns to volume loss on the surface. We hypothesize that damage patterns are good predictors for volumetric wear.

Methods

43 revision and 21 postmortem-retrieved MG II (Zimmer Inc.) tibial UHMWPE components were included in this study. Wear scars and damage patterns on the superior articular surfaces were digitized using a video microscope (SmartScope, OGP). Patterns were parsed into four spatially exclusive categories: delamination, polishing, striations and pitting. The surfaces were measured at 100×100µm using a low-incidence laser on a coordinate measuring machine (SmartScope, OGP). Autonomous mathematical reconstruction of the original surface was used [2] to calculate volume changes on the medial and lateral surfaces as an estimate of wear volume [Fig. 1] Total volume loss was calculated within the observed wear scar, and volume loss under each pattern was calculated and normalized to the total volume loss of its insert.

Objective

It is known that stress shielding frequently occurs after total hip arthroplasty (THA). However, the status of bone metabolism in stress shielding region is not still clear. ¹⁸F-fluoride positron emission tomography (PET) is a useful tool for the quantitative evaluation of bone metabolism, which uptake relates with the activity of bone formation by osteoblast. In this study, we evaluated the status of bone turnover in stress shielding region using ¹⁸F -fluoride PET.

Design

A total of 88 hip joints from 70 cases after THA were analyzed using X-ray and ¹⁸F-fluoride PET. We classified these hips into 2 groups, stress shielding or non-stress shielding group. Each femur was divided into 7 regions by Gruen's zone classification. We measured SUV of ¹⁸F-fluoride PET in these regions and compared SUV to evaluate the difference of bone metabolism between 2 groups.

Introduction

Patient specific surgical guide (PSSG) is a relatively new technique for accurate total knee arthroplasty (TKA), and there are many reports supporting PSSG can reduce the rate of outlier in the coronal plane. We began to use PSSG provided by Biomet (Signature®) and have reported the same results. Before using Signature, we performed TKA by modified gap technique (parallel cut technique) to get the well balanced flexion gap. Signature is the one of the measured resection technique using the anatomical landmarks as reference points on the images of CT or MR taken before surgery. We usually measure the center gap width and gap balance during operation with the special device “knee balancer”(Fig. 1) that can be used on patella reposition. After cutting all of the bone with Signature, gap balance in the extension position was very good but the gap balance was shown slight lateral opening in the 90 degrees flexion position. So we have changed the surgical procedure. We use Signature for cutting only distal femur and proximal tibia to get extension gap and apply the modified gap technique to decide the rotation of the femoral component (Signature with modified gap technique).

The purpose of this study is to compare the gap balance between the two techniques.

Materials & Methods

From November, 2012 through March, 2014, 50 CR type TKA (Vanguard Knee®, Biomet) in osteoarthritis patients were performed using Signature. 25 TKA were performed using only Signature (group S) and other 25 TKA were done using Signature with modified gap technique (group SG). After all osteotomies of femur and tibia were completed, applying femoral trial, center gap width and gap balance (plus means lateral opening angle) were measured using knee balancer with respect to 30 degrees of the knee flexion angle from zero to 120 degrees (Fig. 2).

Introduction

In total joint replacement devices, material loss from the taper junctions is a clinical concern. Previous studies of explanted orthopedic devices have relied on visual scoring methods to quantify the fretting-corrosion damage on the component interfaces. Previous research has shown that visual fretting-corrosion evaluation is correlated to the volume of material loss [1], but scoring is semi-qualitative and does not provide a quantitative measure of the amount of material removed from the surface. The purpose of this study was to develop and validate a quantitative method for measuring the volume of material lost from the surfaces of explanted devices at the taper-trunnion junction.

Methods

10 new exemplar taper adapter sleeves (Ceramtec, Plochingen, Germany) were used for method validation. By using exemplar devices we were able to create clinically realistic taper damage in a controlled and repeatable manner using machining tools. Taper surfaces were measured before and after in vitro material removal using a roundness machine (Talyrond 585, Taylor Hobson, UK). Axial traces were measured on each taper surface using a diamond stylus. The mass of artificially removed material was also measured gravimetrically using a microgram balance (Sartorius, CPA225D, accuracy = ± 0.00003g).

Surface profiles were analyzed using a custom MatLab script and Talymap software was used to provide 3D visualizations of the pattern of material loss. Calculated volumetric material loss was compared to the gravimetric value. A sensitivity analysis was conducted to determine the optimum number of traces to characterize the material loss from taper junctions.

Introduction

Dissatisfaction with the posterior approach to total hip replacement has led to the anterior approach being adopted with enthusiasm in some areas.

Objectives

We aim to assess any difference between the 2 approaches and if so, the magnitude of this difference.

Introduction

Metal-on-metal bearings (MoM) have been reported to release metal ions that are potentially leading to adverse tissue reactions. Alternatively, ceramic-on-ceramic bearings (CoC) are an attractive treatment for young and active patients and composite materials like zirconia toughened alumina (ZTA) have been successfully introduced clinically. One of the most common ZTA-material in CoC is the Biolox® delta, manufactured by Ceramtec. Along with alumina and zirconia, this material also contains traces of chromium, strontium and yttrium. The aim of this study was to analyse the ion release for these materials clinically as well as experimentally.

Material and Methods

Within a clinical trial, three different patient groups were compared: a) a control group without any implants, b) patients, three months after unilateral treatment with Biolox® delta CoC and c) patients, twelve months after unilateral treatment with Biolox® delta CoC. Whole-blood samples were collected and analysed in regards to the trace elements using high-resolution-ICP-MS. In the experimental setup, the leaching behaviour of five Biolox® delta ceramic heads and five CoCr-heads was analysed. The heads were immersed in serum for seven days at 37°C. The ion-release of aluminium, zirconium, cobalt, chromium, strontium and yttrium were detected based on high-resolution-ICP-MS.

BACKGROUND

Hip arthroplasty is an ultimate treatment for individuals with severe hip osteoarthritis. There are several available approaches when performing this type of surgery, however there is a growing interest in using the least invasive procedures. These less invasive procedures aid in healthy bone preservation which may be particularly important for younger populations undergoing hip arthoplasy (Rajakulendran & Field, 2012). Accurate and reliable measurement techniques are needed to better study and monitor the outcome of different implantation techniques during the postop recovery.

OBJECTIVES

To develop a better understanding of spatiotemporal aspects of gait pre- and post- hip arthroplasty through the anterior approach.

Introduction

The application of digital radiography in clinical settings has provided the opportunity to obtain high quality images while reducing the overall cost of imaging, thus this technology is gaining more popularity in clinical settings specifically in orthopaedic clinics ¹. In addition, advanced computer software helps with quick and easy approach to perform preoperative measurements with high accuracy ². Preoperative templating has become one of the standard of care procedures that prepares the surgical team to lower surgical time and more efficiently face intraoperative complications ³. Commonly, the acetabular cup size and femoral stem size are templated and used for estimation process ⁴. However, the goal of this study was to investigate whether patients' demographics would play a role in increasing the accuracy of templating. We hypothesized that preoperative implant templating (acetabular and femoral components), gender, weight, height, and body mass index (BMI) would contribute to higher accuracy of templating in total hip arthroplasty (THA).

Method

Digital radiographs of 468 patients treated with THA from August 2012 to December 2013 at a single institution were reviewed. They aged 59.96 ±12.50 years and 436 of them were diagnosed with osteoarthritis, 53 with avascular necrosis, 13 with failed THA, 2 with infection, 4 post trauma, and 13 with failed hemi arthroplasty. THA templating was conducted by assessing the anteroposterior view of the pelvis that was centered over the pubic symphysis, with the hips in 10° to 15° of internal rotation and we utilized a lateral frog-leg view of the affected hip. A backward stepwise multiple regression model was used to exclude the parameters that had no significant contribution to the accuracy of the measurement.

Introduction

The concept of neck preserving stems, known as short femoral stems or metaphyseal stems has been utilized to improve the outcomes of standard cementless stems. The preservation of the proximal femoral bone stock results in decreasing the potential stress shielding and thigh pain. Additionally, these stems may be used in less invasive procedures and provide the option for easier revision procedures if implant failure occurs. In this study we aim to demonstrate the clinical outcome of direct anterior approach of total hip arthroplasty (THA) with short stem prosthesis.

Methods

In this study, 390 total cases of THA in 345 patients who underwent an anterior approach of THA by using a new type of short-stem prosthesis (Minihip, Corin) between 2009 and 2013 were reviewed.

There were 282 male and 62 female patients and Table 1 summarizes the demographics. In 48 cases avascular necrosis (AVN) was the diagnosis and 339 cases were reported to be due to osteoarthritis. Twenty eight patients were assessed to have American Society of Anesthesiologist (ASA) physical functional score of class I, 258 patients had class II, 103 had class III, and 1 had class IV. Table 2 shows the Charnley classification of the patients.

In the current study we evaluated the outcomes of the surgery by utilizing Hip Disability and Osteoarthritis Outcome Score (HOOS) subscales (Pain, Symptoms, Function in daily living (ADL), Function in sport and recreation (Sport) and hip related Quality of life (QOL)).

Introduction

Deciding the acetabular cup inclination and anteversion is an important step in total hip arthroplasty. Despite numerous studies focusing on enhancement of precise positioning into anatomical safe zone, problem remains regarding which is the “optimal anteversion” and what is the proper anatomical reference during the surgery.

Objectives

The purpose of this study is to evaluate pelvic tilt angle measured in standing lateral view of pelvis in patients with hip osteoarthritis, and to find out the correlations between pelvic tilt angle (on Lewinnek anterior pelvic plane) and optimal anteversion position in total hip arthroplasty surgery.

[Background]

Factors determining improvement of the long-term outcome of total knee arthroplasty include accurate reproduction of lower limb alignment. To acquire appropriate lower limb alignment, tibial component rotation is an important element for outcomes. We usually determine the tibial component rotation using the anatomical rotaional landmark of the proximal tibia and range of motion technique. In addition we followed by confirmation of overall lower limb alignment referring to the distal tibial index. When the tibia have a rotational mismatch between its proximal and distal AP axis, a larger error of the distal tibial index than those of other rotational landmark is of concern. The purpose of this study is to evaluate the reliability of the distal tibial AP axis as a reference axis of tibial compornent rotation in the intraoperative setting.

[Subjects and Methods]

The 86 patients (104 knees) with osteoarthritis of the knee who underwent primary TKA were evaluated with use of computerized tomography scans. A 3D images of the proximal tibial and ankle joint surfaces and foot were prepared, and the reference axis was set. In measurement, the images and reference axes were projected on the same plane. We measured the angle caluculated by the proximal and distal tibial AP axes (torsion angle) in preoperative 3D CT images. As a proximal tibial AP reference axis, AP-1 is a line connecting the medial margin of the tibial tubercle and Middle of the PCL attachment site and AP-2 is a line connecting the 1/3 medial site of the tibial tubercle and center of the PCL attachment site. As a distal tibial AP reference axis, D3 is a line connecting the anteroposterior middle point of the talus, D4 is a perpendicular line of transmalleoler axes, and D5 is the second metatarsal bone axis.

[Background]

Bipolar hemiarthroplasty (following BHA) have historically had poor results in patients with idiopathic osteonecrosis of femoral head (OFNH). However, most recent report have shown excellent results with new generation BHA designs that incorporate advances in bearing technology. These optimal outcomes with bipolar hemiarthroplasty will be more attractive procedure for young patients who need bone stock for future total arthroplasty. The purpose of the current study was to evaluate the clinical and radiographic finding of this procedure for the treatment of OFNH at our institution after 7-to 21years follow-up.

[Subjects and Methods]

We retrospectively reviewed a consecutive series of 29 patients (40 hips) who underwent primary bipolar hemiarthroplasty for ION (36 hips with stage III and 4 hips with stage IV) with a cementless femoral component between 1992 and 2006. Osteonecrosis was associated with corticosteroid use (23 patients), alcohol (16 patients), idiopathic (one patients). The mean follow-up duration was approximately 12 (range 7 to 21) years. Patients were evaluated according to the Japan Orthopaedic Association (JOA) hip score. We evaluate osteolysis and bone response of acetabulum or femur, and migration distance of outer head were calculated at the latest follow-up. Kaplan-Meier survivorship rate was investigated to examine implant failure rate.

Introduction

Malrotation of the tibial component would lead to various complications after total knee arthroplasty (TKA) such as improper joint kinematics, patellofemoral instability, or excessive wear of polyethylene. However, despite reports of internal rotation of the tibial component being associated with more severe pain or stiffness than external rotation, the biomechanical reasons remain largely unknown. In this study, we used a musculoskeletal computer model to simulate a squat (0°–130°–0° flexion) and analyzed the effects of malrotated tibial component on lateral and medial collateral ligament (LCL and MCL) tensions, tibiofemoral and patellofemoral contact stresses, during the weight-bearing deep knee flexion.

Materials and Methods

A musculoskeletal model, replicating the dynamic quadriceps-driven weight-bearing knee flexion in previous cadaver studies, was simulated with a posterior cruciate-retaining TKA. The model included tibiofemoral and patellofemoral contact, passive soft tissue and active muscle elements. The soft tissues were modeled as nonlinear springs using previously reported stiffness parameters, and the bony attachments were also scaled to some cadaver reports. The neutral rotational alignment of the femoral and tibial components was aligned according to the femoral epicondylar axis and the tibial anteroposterior axis, respectively. Knee kinematics and ligament tensions were computed during a squat for malrotated conditions of the tibial component. The tibial rotational alignments were changed from 15° external rotation to 15° internal rotation in 5° increments. The MCL and LCL tensions, the tibiofemoral and patellofemoral contact stresses were compared among the knees with different rotational alignment.

Introduction

Ultra-high molecular weight polyethylene (UHMWPE) tape, which comprised threads of UHMWPE fibers with the thickness less than 0.5 mm, was developed as a flexible fixation device. We describe new techniques using UHMWPE tape for the reattachment of the osteotomised fragment and the repair of intraoperative calcar fractures in total hip arthroplasty (THA).

Patients & Methods

We reviewed the medical records and radiographs of the studied subjects after approval of this study by the institutional review board committee. Experiment 1: Between October 2011 and May 2012, 60 consecutive primary THAs were performed with the mini-trochanteric approach, which involved reattaching the osteotomised fragment using UHMWPE tape (Nesplon; Alfresa Pharma, Osaka, Japan). [Fig.1] By splitting the anterior one-fourth of the gluteus medius, the minitrochanteric osteotomy, a half-ellipsoid body about 15 mm long, 10 mm wide, and 5 mm deep, is performed using a curved chisel. After implanting of the prosthesis, the osteotomised fragment is reattached by using two 3-mm wide Nesplon tapes. Using 2.4 mm Kirshner wire, two sets of drill holes are created below the trochanteric bed of the femur. Nesplon tapes are passed through each drill hole and penetrated over the trochanteric fragment. Nesplon tape is tied using a double-loop sliding knot in conjunction with a special tightening gun tensioner up to 20 kgf. [Fig.2] The radiographic results were retrospectively analyzed to determine the incidence of nonunion and complications related to trochanteric site. Hip functional results were rated according to the Japanese Orthopedic Association (JOA) hip score. Experiment 2: Between July 2011 and May 2012, 5-mm wide Nesplon tapes were used for restoration of intraoperative femoral fractures in 4 primary THAs. For the repair of intraoperative proximal femoral fractures, 5-mm wide Nesplon tape is tightened with cerclage wiring technique using the gun tensioner up to 30 kgf. [Fig.3] The postoperative radiographic changes were analyzed.

Introduction

Recent implant design trends have renewed concerns regarding metal wear debris release from modular connections in THA. Previous studies regarding modular head-neck taper corrosion were largely based on cobalt chrome (CoCr) alloy femoral heads. Comparatively little is known about head-neck taper corrosion with ceramic femoral heads or about how taper angle clearance influences taper corrosion. This study addressed the following research questions: 1) Could ceramic heads mitigate electrochemical processes of taper corrosion compared to CoCr heads? 2) Which factors influence stem taper corrosion with ceramic heads? 3) What is the influence of taper angle clearance on taper corrosion in THA?

Methods

100 femoral head-stem pairs were analyzed for evidence of fretting and corrosion. A matched cohort design was employed in which 50 ceramic head-stem pairs were matched with 50 CoCr head-stem pairs based on implantation time, lateral offset, stem design and flexural rigidity. Fretting corrosion was assessed using a semi-quantitative scoring scale where a score of 1 was given for little to no damage and a score of 4 was given for severe fretting corrosion. The head and trunnion taper angles were measured using a roundness machine (Talyrond 585, Taylor Hobson, UK). Taper angle clearance is defined as the difference between the head and trunnion taper angles.

Purpose

The purpose of this study was to analyze rotational kinematic patterns in knees treated with either cruciate-retaining (CR) or posterior-stabilized (PS) total knee arthroplasty (TKA), using an intra-operative navigation technique, and to clarify the factors that affect of the rotational kinematics and the difference rotational kinematics patterns between CR- and PS- TKA.

Methods

A total of 35 knees (35 patients) were included in this study, deformed valgus, sever flexion contractures, and highly unstable knees were excluded. These knees were allocated to CR (NexGen CR-Flex) or PS (NexGen PS-Flex) implants and underwent TKA with a computer navigation technique (precision N Knee Navigation Software v4.0; Stryker). There was no significant difference in pre-operative parameters between CR- and PS-TKA group: age, femorotibial angle (FTA), and chondylar twist angle (CTA).

We measured two points during surgery. First, the skin incision was made and subcutaneous tissue was exposed. The joint capsule was temporality closed by three or four strand suture. Second, after the surgery was completed with satisfactory alignment and soft tissue balance, immediately following wound closure the measurement procedure was repeated.

The surgeon gently applied a manual range of motion from full extension to flexion. The angle of internal rotation in tibia to the functional plane of tibia and femur was measured automatically at max extension, 0, 30, 45, 60, 90 degrees, and max flexion throughout the passive knee motion.

«Purpose»

High tibial osteotomy (HTO) is a useful treatment option for osteoarthritis of the knee. Closing-wedge HTO (CW-HTO) had been mostly performed previously, but the difficulties of surgical procedure when total knee arthroplasty (TKA) conversion is needed are sometimes pointed out because of the severe deformity in proximal tibia. Recently, opening-wedge HTO (OW-HTO) is becoming more popular, but the difference of the two surgical techniques about the influence on proximal tibia deformity and difficulties in TKA conversion are not fully understood. The purpose of this study was to compare the influence of two surgical techniques with CW-HTO and OW-HTO on the tibial bone deformity using computer simulation and to assess the difficulties when TKA conversion should be required in the future.

«Methods»

In forty knees with medial osteoarthritis, the 3D bone models were created from the series of 1 mm slices two-dimensional contours using the 3D reconstruction algorithm. The 3-D imaging software (Mimics, materialize NV, Leuven, Belgium) was applied and simulated surgical procedure of each CW-HTO and OW-HTO were performed on the same knee models. In CWHTO, insertion level was set 2cm below the medial joint line [Fig.1]. While in OW-HTO, that was set 3.5cm below the medial joint line and passed obliquely towards the tip of the fibular head [Fig.2]. The correction angle was determined so that the postoperative tibiofemoral angle would be 170 degrees. The distance between the center of resection surface and anatomical axis, and the angle of anatomical axis and mechanical axis were measured in each procedure. Secondly, a simulated TKA conversion was operated on the each tibial bone models after HTO [Fig.3]. The distance between the nearest points of tibial implant and lateral cortical bone was assessed as the index of the bone-implant interference.

Introduction

Surgical techniques for implant alignment in total knee arthroplasty (TKA) is a expanding field as manufacturers introduce patient-specific cutting blocks derived from 3D reconstructions of pre-operative imaging, commonly MRI or CT. The patient-specific OtisMed system uses a detailed MRI scan of the knee for 3D reconstruction to estimate the kinematic axis, dictating the cutting planes in the custom-fit cutting blocks machined for each patient. The resulting planned alignment can vary greatly from a neutral mechanical axis. The purpose of this study was to evaluate the early fixation of components in subjects randomized to receive shape match derived kinematic alignment or conventional alignment using computer navigation. A subset of subjects were evaluated with gait analysis.

Methods

Fifty-one patients were randomized to receive a cruciate retaining cemented total knees (Triathlon, Stryker) using computer navigation aiming for neutral mechanical axis (standard of care) or patient-specific cutting blocks (OtisMed custom-fit blocks, Stryker). Pre-operatively, all subjects had MRI scans for cutting block construction to maintain blinding. RSA exams and health outcome questionnaires were performed post-operatively at 6 week, 3, 6, and 12 month follow-ups. A subset (9 subjects) of the patient-specific group underwent gait analysis (Optotrak TM 3020, AMTI force platforms) one-year post-TKA, capturing three dimensional (3D) knee joint angles and kinematics. Principal component analysis (PCA) was applied to the 3D gait angles and moments of the patient-specific group, a case-matched control group, and 60 previously collected asymptomatic subjects.

Introduction

Debate over appropriate alignment in total knee arthroplasty has become a topical subject as technology allows planned alignments that differ from a neutral mechanical axis. These surgical techniques employ patient-specific cutting blocks derived from 3D reconstructions of pre-operative imaging, commonly MRI or CT. The patient-specific OtisMed system uses a detailed MRI scan of the knee for 3D reconstruction to estimate the kinematic axis, dictating the cutting planes in the custom-fit cutting blocks machined for each patient [1, 2].

The purpose of this study was to evaluate the correlation between post-operative limb alignment and implant migration in subjects receiving shape match derived kinematic alignment.

Methods

In a randomized controlled trial comparing patient-specific cutting blocks to navigated surgery, seventeen subjects in the patient specific group had complete 1 year data. They received cruciate retaining cemented total knee replacements (Triathlon, Stryker) using patient-specific cutting blocks (OtisMed custom-fit blocks, Stryker). Intra-operatively, 6–8 tantalum markers (1 mm diameter) were inserted in the proximal tibia. Radiostereometric analysis (RSA) [3, 4] exams were performed with subjects supine on post-operative day 1 and at 6 week, 3, 6, and 12 month follow-ups with dual overhead tubes (Rad 92, Varian Medical Systems, Inc., Palo Alto, CA, USA), digital detectors (CXDI-55C, Canon Inc., Tokyo, Japan), and a uniplanar calibration box (Halifax Biomedical Inc., Mabou, NS, Canada). RSA exams were analyzed in Model-based RSA (Version 3.32, RSAcore, Leiden, The Netherlands. Post-operative limb alignment was evaluated from weight-bearing long-leg films.

Introduction

The dual mobility design concept for acetabular liners is intended to reduce the risk of dislocation and increase range of motion, but the wear pattern of this design is unclear and may have implications in implant fixation. Additionally, the solid back cups do not have the option for supplementary screw fixation, providing an additional smooth articulating surface for the liner to move against. The objective of this study was to assess cup fixation by measuring implant migration. A secondary objective was to evaluate the mobile bearing motion after rotating the hip.

Methods

Thirty subjects were recruited in a consecutive series prospective study and received Anatomic Dual Mobility (Stryker Orthopedics) uncemented acetabular components with mobile bearing polyethylene liners through a direct lateral approach. Femoral stems were cemented (Exeter) or uncemented (Accolade, Stryker Orthopedics). The femur, acetabulum, and non-articulating surface of the polyethylene liner were marked with tantalum beads. Radiostereometric analysis (RSA) exams were performed post-operatively and at 6 weeks, 3, 6, months, and at 1 year. At the 1 year exam, a frog leg RSA exam was performed to assess the mobility of the cup compared to its position during a supine exam.

Introduction

The viscoelastic cervical disk prosthesis ESP is an innovative one-piece deformable but cohesive interbody spacer. It is an evolution of the LP ESP lumbar disk implanted since 2006. CP ESP provides 6 full degrees of freedom about the 3 axes including shock absorption. The prosthesis geometry allows limited rotation and translation with resistance to motion (elastic return property) aimed at avoiding overload of the posterior facets. The rotation center can vary freely during motion (figure 1)

It thus differs substantially from current prostheses. This study reports the results of a prospective series of 49 patients who are representative of the current use of the ESP implant since 2012.

Material and methods

The surgeries were performed by 3 senior surgeons. There were 34 women and 15 men in this group. The average age was 44±7 (32–59). The implantation was single level in 78 % of cases. 55 CP ESP prostheses were analyzed.

Clinical data and X-rays were collected at the preoperative time and at 3, 6, and 12 months post-op.

The functional results were measured using Neck and Arm VAS, NDI, SF-36, (physical componentPCS and mental component MCS). The analysis was performed by a single observer who was independent from the selection of patients and from the surgical procedure.

Introduction

Coronal misalignment of the lower limbs is closely related to the onset and progression of osteoarthritis. In cases of severe genu varus or valgus, evaluating this alignment can assist in choosing specific surgical strategies. Furthermore, restoring satisfactory alignment after total knee replacement promotes longevity of the implant and better functional results. Knee coronal alignment is typically evaluated with the Hip-Knee-Ankle (HKA) angle. It is generally measured on standing AP long-leg radiographs (LLR). However, patient positioning influences the accuracy of this 2D measurement. A new 3D method to measure coronal lower limb alignment using low-dose EOS images has recently been developed and validated. The goal of this study was to evaluate the relevance of this technique when determining knee coronal alignment in a referral population, and more specifically to evaluate how the HKA angle measured with this 3D method differs from conventional 2D methods.

Materials and methods

70 patients (140 lower extremities) were studied for 2D and 3D lower limb alignment measurements. Each patient received AP monoplane and biplane acquisition of their entire lower extremities on the EOS system according the classical protocols for LLR. For each patient, the HKA angle was measured on this AP X-ray with a 2D viewer. The biplane acquisition was used to perform stereoradiographic 3D modeling. Valgus angulation was considered positive, varus angulation negative. Student's T-test was used to determine if there was a bias in the HKA angle measurement between these two methods and to assess the effect of flexion/hyperextension, femoral rotation and tibial rotation on the 2D measurements. One operator did measurements 2 times.

Introduction

The assessment of leg length is essential for planning the correction of deformities and for the compensation of length discrepancy, especially after hip or knee arthroplasty. CT scan measures the “anatomical” lengths but does not evaluate the “functional” length experienced by the patients in standing position. Functional length integrates frontal orientation, flexion or hyperextension. EOS system provides simultaneously AP and lateral measures in standing position and thus provides anatomical and functional evaluations of the lower limb lengths.

The objective of this study was to measure 2D and 3D anatomical and functional lengths, to verify whether these measures are different and to evaluate the parameters significantly influencing these potential differences

Material and Methods

70 patients without previous surgery of the lower limbs (140 lower extremities) were evaluated on EOS images obtained in bipodal standing position according to a previously described protocol.

We used the following definitions:

Other parameters measured are HKA, HKS, femoral and tibial mechanical angles (FMA, TMA), angles of flexion or hyperextension of the knee, femoral and tibial torsion, femoro-tibial torsion in the knee, and cumulative torsional index (CTI). All 2D et3D measures were evaluated and compared for their repeatability.

Introduction

The gold standard for knee surgery is the restoration of the so-called «neutral mechanical alignment ». Recent literature as pointed out the patients with «constitutional varus »; in these cases, restoring neutral alignment could be abnormal and even undesirable. The same situation can be observed in patients with «constitutional valgus alignment ». To date, these outliers cases have only been explored focusing on the lower limb; the influence of the pelvic morphotype has not been studied. Intuitively, the pelvic width could be a significant factor. The EOS low dose imaging technique provides full body standing X-rays to evaluate the global anatomy of the patient. This work explores the influence of the pelvic parameters on the frontal knee alignment.

Material and methods

– We included 170 patients (340 lower extremities). 2 operators performed measurements once per patient on AP X-rays.

Inter-Operator Reliability was calculated with Intra-class Correlation Coefficient (ICC) and Inter-Reader Agreement was assessed with Bland-Altman test.

A relationship between IMAD and GMAD to the other parameters was assessed using Pearson's correlation coefficient.

Introduction

Junior level orthopaedic surgery residents who train with a virtual surgical simulator can lead to improved arthroscopy performance.

Methods

Study participants were first and second year orthopaedic surgery residents at a single institution who were randomized to either train on the virtual reality surgical simulator (Insight Arthro VR) for a total of 2.5 hours (n=8) or receive 2 hours of didactic lectures with models (non-simulator) (n=6). Both groups were then evaluated in both knee and shoulder arthroscopy using a cadaver. Performance was measured by time to completion of a standardized protocol checklist and cartilage-grading index (CGI) (scale 0–10).

Purpose

Use of theguide angle method using intramedullary guide angle for distal femoral cutting in total knee arthroplasty may cause error when rotation of the femur occurs or the insertion point of the intramedullary guide is incorrectly positioned in preoperative radiography. On the other hand, use of the measured cutting method, in which resection of distal femoral condyles is performed according to predicted measured thickness in a preoperative radiograph can allow for correction of these errors intraoperatively. Therefore, we compared these two distal femoral bone cutting methods for restoration of accurate coronal alignment.

Methods

Between 2010 and 2012, 47 patients (70 knees) underwent total knee arthroplasty for treatment of osteoarthritis with varus deformity and flexion contracture less than 10 degrees. Bone resection depending on distal femur resection thickness measured before the operation was performed in 38 cases (Group I). Distal femoral cutting using the guide angle was performed in 32 cases (Group II). Radiographic evaluation, including mean value of lower leg mechanical axis angle and the frequency of errors of more than 3 degrees, was performed for comparison between the two groups.

Purpose

Evaluation of status of collateral ligament & prediction of post-op alignment is important for partial knee replacement because during UKA the ligament can't be released & overcorrection or severe varus alignment result in poor clinical result. Evaluation of ligament could be done with valgus stress or distraction. The authors compare the stress view & distractive CT scanogram. to know the effectiveness regarding the prediction of final alignment.

Material & Method

19 knee from the 16 people receiving partial knee replacement was studied, we measure the anatomical axis &mechanical axis of the valgus stress view & distractive CT scanogram & post-operative whole leg radiogram.

Purpose

Although the use of stems in revision total knee arthroplasty (RTKA) enhances survival by improving the stability of implant, questions as to the optimal fixation method as well as the vertical extent of the cement, remain unanswered. This study aimed 1) to determine the correlation between the vertical extent of cement and implant loosening; and 2) to determine the minimum cementing extent for a stable implant in revision TKA with a hybrid technique.

Materials and Methods

We retrospectively analyzed 109 stemmed RTKAs with average follow-up of 63 months. In each case, a single varus-valgus constrained implant was used and fixed with a hybrid technique. During surgery, stem was partially covered with cement beyond stem-implant junction. Stability of implant was evaluated according to the modified Knee Society Radiographic Scoring System. Cementing extent was defined as length from implant base to the end of the radiopaque line around the stem. The correlation between the vertical cementing extent and implant stability was analyzed, and the minimal vertical cementing extent for a stable implant was evaluated with a scatter plot.

INTRODUCTION

Total knee arthroplasty (TKA) is a very successful procedure with good clinical outcomes. However, the effects of obesity on TKA outcomes remain controversial and inconclusive. The objective of this study was to quantify the biomechanical effects of simulated obesity on Cruciate Retaining (CR) and Posterior Stabilized (PS) TKA in human cadaveric knees. We hypothesized that biomechanical characteristics of CR TKA will be less dependent on simulated obesity compared to PS TKA.

METHODS

Eight cadaveric knees (4 male, 4 female) average age 68.4 years (range, 40–86 years) underwent TKA and were tested using a custom knee testing system. Specifically, Cruciate Retaining (CR) and Posterior Stabilized (PS) Lospa Knee System (Corentec Inc.) were implanted and tested sequentially using internal control experimental design. The muscle loading was determined based on the physiological cross-sectional area ratio of the quadriceps and hamstring muscles. The ratios were then applied to CDC data representing the average male height and used to simulate a BMI of 25, 30, and 35 at knee flexion angles (KFA) of 15, 30, 45, 60, 75, and 90 degrees. Patellofemoral and tibiofemoral joint contact areas and pressures were measured using the K-scan sensor system (Tekscan Inc, South Boston, MA). Contact area, force, pressure and peak contact pressure were obtained and analyzed for each specimen. Knee kinematics were quantified using a Microscribe 3DLX digitizer (Revware Inc, Raleigh, North Carolina). Repeated measure analysis of variance with a Tukey post hoc test was used to compare loading conditions. Comparisons between the CR and PS TKA groups were made with a paired t-test. The significance level was set at 0.05.

Introduction

Reverse total shoulder arthroplasty continues to have a high complication rate, specifically with component instability and scapular notching. Therefore, the purpose of this study was to quantify the effects of humeral component neck angle and version on impingement free range of motion.

Methods

A total of 13 cadaveric shoulders (4 males and 9 females, average age = 69 years, range 46 to 96 years) were randomly assigned to two studies. Study 1 investigated the effects of humeral component neck angle (n=6) and Study 2 investigated the effects of humeral component version (n=7). For all shoulders, Tornier Aequalis® Reversed Shoulder implants (Edina, MN) were used. For study 1, the implants were modified to 135, 145 and 155 degree humeral neck shaft angles and for Study 2 a custom implant that allowed control of humeral head version were used.

For biomechanical testing, a custom shoulder testing system that permits independent loading of all shoulder muscles with six degree of freedom positioning was used. (Figure 1) Internal control experimental design was used where all conditions were tested on the same specimen.

Introduction

Moderately crosslinked, thermally treated ultrahigh molecular weight polyethylene (UHMWPE) has to date demonstrated a good balance of wear resistance and mechanical properties. MARATHON™ Polyethylene (DePuySynthes Joint Reconstruction, Warsaw, IN) is made from polyethylene resin GUR 1050, gamma-irradiated at a dose of 5.0 Mrads to create crosslinking of polyethylene, and followed by a remelting process to eliminate free radicals for oxidative stability. 10-year clinical study [1] and laboratory wear simulation tests [2–3] have reported excellent wear performance of the MARATHON poly.

There continues to be demand for improved head-to-shell ratio acetabular systems because larger head sizes have the benefits of increased stability and range of motion. The increased head-to-shell ratio is often times achieved by using a reduced liner thickness. One of the clinical concerns of thinner poly liners is the potential for rim fracture, particularly in the occurrences of rim loading or impingement at high cup angles [4–7].

This study investigated the performance of thinner poly liners to the challenge of high angle rim loading and neck-to-liner impingement.

Materials and Methods

Three groups of ETO sterilized MARATHON polyethylene liners (ID/OD: 28/44, 32/48, and 36/52 mm) were paired with matching CoCrMo heads (n=6 each group). To simulate rim loading, liners were assembled in the metal shells tilted at 64° (Figure 1) with sinusoidal loading (0 to 5000N at 3Hz) in a 37°C water bath for 5-million cycles or until component failure, whichever occurred first.

For neck-liner impingement testing, metal shells were potted at 54º (in the abduction/adduction plane with a ±10° of motion per ISO 14242–1 [8]) on a hip simulator (n=4 each group) using a physiological loading (max 3000N at 1Hz) for 3-million cycles (Figure 2). The impingement occurred at 64º during the simulated gait cycle (Figure 3).

The liners were inspected every million cycles, using a high intensity light to search for signs of crack initiation and/or fractures. Both test methods were validated to be able to replicate liner fractures.

Objective

By retrospective analysis of clinical data, to find new risk factors for postoperative dislocation after total hip replacement and the dose-effect relationship when multiple factors work simultaneously.

Methods

A nested case-control study was used to collect the dislocated hips from 5513 primary hip replacement case from 2000 to 2012. Apart from the patients with given cause of dislocation, 39 dislocated hips from 38 cases were compared with 78 hip from 78 cases free from dislocation postoperatively, which matched by the admission time. The factors that may affect the prosthetic unstable was found by the univariate analysis, and then they were performed multivariate logistic regression analysis and evaluation of a dose-effect factors.

Background

Operative fixation of acute tendo-achilles ruptures remains controversial. Standard surgical exposure is associated with and increased risk of wound breakdown and infections. The mini-open technique was developed to minimise these risks and provide anatomical reduction/apposition of the tendon rupture.

Methods

We present a retrospective case series of 27 patients who were treated operatively for acute Achilles tendon rupture in the hands of 1 surgeon, between 4–6 years post operatively, using Achillon instrumentation. Post operatively they were treated with an air cast boot and 3 wedges, bringing the foot into neutral by 6 weeks followed by a rehabilitation programme. The patients were contacted via telephone and consent was obtained. The complications, Leppilahti score and ATRS score were then calculated.

Introduction

Adverse wear related failure (AWRF) after metal-on-metal hip resurfacing arthroplasty (HRA) has been described as a new failure mechanism. We describe the results of revision of these failures.

Methods

Between July 1999 and Jan 2014, a single surgeon performed 3407 HRA. Nine (9/3407; 0.3%) cases in 8 patients were revised due to AWRF. In two additional revisions for AWRF the primary HRA was done elsewhere. There were a total of 11 revisions (9 women, 2 men) for AWRF cases reported in this study. The primary diagnoses were OA in 7 and dysplasia in 4. At the time of the primary surgery, the average age was 50±5 years and the average BMI was 27±4. The average femoral component sizes were 46±3mm. Only the acetabular component was revised in eight cases, both components were revised in 4 cases (revised to THA), three of these four used metal on metal bearings. A postop CT was requested for all patients after revision. 4 scans were of sufficient quality to analyze implant positions. Algorithms for metal artifact reduction were utilized to obtain high quality 2D images (Figure 1); 3D CAD models of the bones and implants were regenerated in order to calculate the acetabular inclination and anteversion angle (Figure 2).

Introduction

Most metal-on-metal hip resurfacing implants currently being used worldwide utilize bone ingrowth fixation on the acetabular side, but cement fixation remains the standard method of fixation on the femoral side. Our hypothesis is that bone ingrowth fixation of a fully porous-coated component is superior to cement fixation of the femoral hip resurfacing component.

Methods

From March 2007 to Jan 2009, 429 consecutive metal-on-metal hip resurfacing arthroplasties were performed by a single surgeon in 396 unselected patients using Biomet uncemented femoral and acetabular components. All of these were at least 5-years postop. Three patients died with causes unrelated to their hip arthroplasty. The three most common primary diagnoses were osteoarthritis in 318 (74%) cases, dysplasia in 66 (15%) hips, and osteonecrosis in 19 (4%) hips. The average size of the femoral component was 50 ± 4 cm. All pre-operative, intra-operative, and post-operative data were prospectively collected and entered into our database for review. All patients are allowed unrestricted activity including impact sports after 6 months.

Introduction

Protective hard coatings are appealing for several technological applications like solar cells, organic electronics, fuel cells, cutting tools and even for orthopaedic implants and prosthetic devices. At present for what concerns the application to prosthetic components, the coating of the surface of the metallic part with low-friction and low-wear materials has been proposed [1]. Concerning the use of ceramic materials in joint arthroplasty, zirconia-toughned-alumina (ZTA) reported high strength, fracture toughness, elasticity, hardness, and wear resistance [2]. The main goal of this study was to directly deposit ZTA coating by using a novel sputter-based electron deposition technique, namely Pulsed Plasma Deposition (PPD) [3]. The realized coatings have been preliminary characterized from the point of view of morphology, wettability, adhesion and friction coefficients.

Materials and methods

ZTA coatings were deposited by PPD technique, which is able to maintain the stoichiometry of the starting target. In this case we started from a cylindrical ZTA target (30 mm diameter × 5 mm thickness, 75% alumina / 25% zirconia). The morphology, micro-structure and chemistry of deposited coatings were characterized by Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-ray Spectrosopy (EDS) and Atomic Force Microcscope (AFM). Coating-substrate interface quality were investigated by microscratch tests. The degree of wetting was estimated by measuring the contact angle between a drop of 1 ml of ultrapure water and the surface of the sample. Preliminary ball-on-disk tribological tests were carried out in air and deionized water coupling ZTA-coated stainless steel ball (AISI 420, 3 mm radius, grade 200) against medical grade UHMWPE to evaluate the friction of the proposed coupling.