INTRODUCTION

It is generally accepted that strong hammering is necessary for the press fit fixation of a joint prosthesis. In this regard, large stress must remain within bone tissues for a long period. This residual stress is, however, some different from the feasible mechanical stimuli for bone tissues because that is stationary, continuous and directed from within outward unlike physiological conditions. The response on this residual stress, which may induce the disorder of the fixation of implant, has not been discussed, yet.

In the present study, we designed an experimental method to exert a stationary load from inside of a femur of a rat by inserting a loop spring made from a super elastic wire of titanium alloy. Response of the femur was assessed by bone morphology mainly about the migration of the wire into the bone twelve weeks after the implantation.

MATERIALS AND METHODS

We developed a method using a loop spring made of super elastic wire of titanium alloy, which can maintain sufficient magnitude of stress in a rat femur during the experimental period. The loop spring was fabricated with a wire of 0.4 mm diameter before the quenching process. Eleven Wistar rats of ten weeks old were used for the experiments. The loop spring was inserted the right femur, as shown in Figure 1. The left femur was remained intact. The compressive load was added from within outward of bone marrow when the spring was compressed with the insertion into a bone marrow of a rat femur, as shown in Figure 2. The average contact stress was calculated by dividing the elastic force by the spring and bone contact area. The contact stress was distributed from 62 to 94 MPa, which are sufficiently lower than the yield stress of cortical bone [1]. The assessment of bone morphology around the implanted loop spring was performed by micro-CT imaging after the twelve weeks of cage activity.

Introduction

First-generation annealed HXLPE has been clinically successful at reducing both clinical wear rates and the incidence of osteolysis in total hip arthroplasty. However, studies have observed oxidative and mechanical degradation occurring in annealed HXLPE. Thus, it is unclear whether the favorable clinical performance of 1st generation HXLPE is due to the preservation of bearing surface tribological properties or, at least partially, to the reduction in patient activity. The purpose of this study was to evaluate the in vitro wear performance (assessed using multidirectional pin-on-disk (POD) testing) of 1^st-generation annealed HXLPE with respect to in vivo duration, clinical wear rates, oxidation, and mechanical properties.

Materials and Methods

103 1^st-generation annealed HXLPE liners were collected at revision surgery. 39 annealed HXLPE liners were selected based on their implantation time and assigned to three equally sized cohorts (n=13 per group); short-term (1.4–2.7y), intermediate term (5.2–8.0y) and long-term (8.3–12.5y). From each retrieved liner, two 9-mm cores were obtained (one from the superior region and one from the inferior region). Sixteen cores were fabricated from unimplanted HXLPE liners that were removed from their packaging and six pins from unirradiated GUR 1050 resin served as positive controls. Multidirectional POD wear testing was conducted against wrought CoCr disks in a physiologically relevant lubricant (20 g/L protein concentration) using a 100-station SuperPOD (Phoenix Tribology, UK). Each pin had its own chamber with 15mL lubricant maintained at 37±1°C. An elliptical wear pattern with a static contact stress of 2.0 MPa was employed. Testing was carried out to 1.75 million cycles at 1.0 Hz and wear was assessed gravimetrically. POD wear rates were calculated using a linear regression of volumetric losses. In vivo penetration was measured directly using a calibrated micrometer. Oxidation was assessed on thin films obtained from superior and inferior regions of the liners (ASTM 2102). Mechanical properties were assessed using the small punch test (ASTM 2183).

Introduction

In THA, fretting corrosion at the head-stem taper junction has emerged as a clinical concern that may result in adverse local tissue reactions, even in patients with a metal-on-polyethylene bearing [1]. Taper junctions that employ a ceramic head have demonstrated reduced corrosion at the interface [2]. However, during revision surgery with a well-fixed stem, a titanium sleeve is used in conjunction with a ceramic head to ensure proper fit of the head onto the stem and better stress distribution. In vitro testing has suggested that corrosion is not a concern in sleeved ceramic heads [3]; however, little is known about the in vivo fretting corrosion of the sleeves. The purpose of this study was to investigate fretting corrosion in sleeved ceramic heads.

Materials and Methods

Between 2001 and 2014, 35 sleeved ceramic heads were collected during revision surgery as part of a multi-center retrieval program. The sleeves were all fabricated from titanium alloy and manufactured by 4 companies (CeramTec (n=14), Smith & Nephew (Richards, n=11), Stryker (n=5), and Zimmer (n=5)). The femoral heads were made from 3 ceramics (Alumina (n=7), Zirconia (n=11), and Zirconia-toughened Alumina (n=17)). Sleeve dimensions (length and thickness) were measured using calibrated calipers. Fretting corrosion of the sleeves and available associated stems was scored using a 4-point, semi-quantitative scoring system [4], with 1 being little-to-no damage, and 4 corresponded to severe fretting corrosion. Five sleeves could not be extracted; thus the external surface was not scored.

Introduction

The direct anterior (DA) approach for total hip arthroplasty has demonstrated successful short term outcomes. However, debate remains about which patients are candidates fo this approach. To our knowledge, there are no studies which specifically investigate short-term outcomes in obese versus non-obese patients undergoing THA through a DA approach. The purpose of this study was to evaluate complication rates and short term outcomes of obese, pre-obese, and normal BMI patients undergoing THA through DA approach.

Methods

A retrospective review of 151 consecutive patients who underwent unilateral THA through a DA approach for osteoarthritis or avascular necrosis was performed after IRB approval. Forty patients had a normal BMI, 54 were pre-obese, and 57 were obese by WHO classification (37 class I obese, 12 class II obese, and 8 class III obese). Electronic and paper charts were reviewed to determine differences in surgical time, length of stay, disposition, wound and major complications, and short term outcome measures.

Conclusion

Because of abnormal stand up of long lasting knee OA patients, they start to put pressure on their shoulder to climb on their body. Even their cane or crutches use are not in regular and academic rules. So, we nominate this entity: shoulder knee syndrome as a negative criteria that interferes in out come.

Introduction

The rapidly expanding aging population in the UK are living longer than ever before, which is reflected by the rising number of relatively fit and healthy people that sustain fracture NOF (neck of femur). According to current NICE (National institute for health clinical excellence) guidelines a large proportion of fracture NOF patients meet the requirements to have a total hip arthroplasty (THA) for this injury. Dislocation rate of THA can be as high as 20% for patients with fracture NOF, which is a disastrous complication in these vulnerable patients. Numerous techniques have been adopted to minimise the risk of dislocation. The use of dual mobility (tripolar) acetabular components is one such strategy with a proven track record in the literature that is employed by surgeons at our institute.

Objectives

To assess the dislocation rate in patients with fracture NOF treated with dual mobility (tripolar) THAs in our unit.

Introduction

Restoration of a neutral mechanical axis has been a widely held tenet of primary total knee arthroplasty (TKA), however new technologies are recently being marketed which claim correction of alignment deformity is unimportant. This study was undertaken to determine whether the outcome of aseptic loosening was associated with post-operative mal-alignment of the mechanical axis.

Methods

A 1:9 matched case-control analysis was conducted within a cohort of 1,030 consecutive cemented posterior stabilized TKAs with 7 to 11.5 yrs follow-up (average 9 yrs). Aseptic loosening had occurred in 10 knees (1.0%). Nine controls were randomly selected for each case within matching criteria for age and minimum time in situ. Post-operative mechanical alignment was determined using retrieved long leg radiographs. Age-adjusted relative risk was estimated using conditional logistic regression.

Background

Restoration of physiologic rotational kinematics after total knee replacement has been difficult to achieve using modern dual M/L radius knee designs. This study was undertaken to determine whether a change in femoral shape substituting for the effect of the menisci in load sharing and motion accommodation would result in more normal rotational post arthroplasty kinematics.

Methods

17 knees reconstructed more than twelve months previously with a tricompartmental cemented knee replacement using a single F/E radius, miniscal substituting, a fixed bearing total knee were studied fluoroscopically while performing closed chain activities. The patients were studied during level gait, deep knee bending, rising from a chair, and kneeling. Images were converted from 2 to 3d and joint kinematics were measured using edge recognition softwear.

Introduction

For preoperative planning of Total Hip Arthroplasty (THA) it is paramount to choose the correct implant size to avoid subsidence with too small a component or fracture with too large a component. This planning can be done either in 2D or 3D. 2D templating from X-rays frontal images remains the gold standard technique in THA preoperative planning despite the lower accuracy with uncemented components. 3D planning techniques require a CT-Scan examination overexposing patients to radiation. Biplanar EOS^® radiographs are an alternative to obtain bone 3D reconstructions with a very low dose of radiation. The objective of this study was to evaluate the accuracy and reproducibility a novel 3D technique for THA preoperative planning based on biplanar low-dose radiographs.

Materials and methods

31 patients (20 women, 11 men, average age 66.1 y/o) who underwent a primary THA (Hardinge anterolateral approach) were included. Two senior orthopedic surgeons (Op_1 and Op_2) performed the pre-operative planning: (1) In 2D superimposing templates of the cup and the stem on CR radiographs. The CR images had a magnification coefficient of 1.15. (2) In 3D using dedicated hipEOS (EOS Imaging, France) software. 2D planning was performed once by each operator, 3D planning twice.

3D planning with hipEOS [Figure 1] was performed by importing 3D models of the stem and cup and superimposing them on frontal-lateral EOS^® radiographs. This software proposes an initial estimate of the components size and position. If necessary, the user can correct the size of the stem and perform translations and rotations of the 3D models in order to correct the position, while clinical parameters such as the cup anteversion and inclination, as well as the femoral offset and leg length are automatically recalculated.

To evaluate the accuracy, we have compared the 2D and 3D planning with respect to the actual size implanted during the surgery. To evaluate reproducibility we have calculated the Intra-class Correlation Coefficient (ICC) of both techniques.

Introduction

Patellofemoral (PF) complications are among the most frequently observed adverse events after total knee arthroplasty (TKA). It has been reported that PF complications after TKA include decreasing knee range of motion, anterior knee pain, quadriceps and patellar-tendon rupture, patellar subluxation, and partial abrasion and loosening of the patellar component. Although recent improvements in surgical technique and prosthetic design have decreased these complications, the percentage of patients who have a revision TKA for PF complications still ranged up to 6.6% to 12%. For the present study, we hypothesized that the alignment of the femoral component is correlated with PF contact stress. The purpose of this study was to investigate the relationship between femoral component alignment and PF contact stress in vivo, using a pressure sensor in patients who had favorable extension-flexion gap balance during TKA.

Methods

Thirty knees with medial compartment osteoarthritis that underwent posterior stabilized mobile-bearing TKA using identical prostheses (PFC Sigma RPF; Depuy, Warsaw, IN, USA) by a single surgeon (TM) with modified gap technique under a computed tomography (CT)-based navigation system (Vector Vision 1.61; Brain Lab, Heimstetten, Germany) were evaluated. PF contact stress was measured intraoperatively and compared with the alignment of the femoral component including intraoperative navigation data concerning medial shift of the patella and lateral tilt of the patella, postoperative coronal femoral component angle (alpha angle), postoperative sagittal femoral component angle (gamma angle), postoperative condylar twist angle (CTA), postoperative lateral condylar lift-off angle, and postoperative mechanical femoral component angle (mFCA). In addition, postoperative Insall-Salvati ratio (I-S ratio) was measured by dividing the length of patellar tendon by the greatest diagonal length of the patella.

Introduction

Patients undergoing total knee arthroplasty (TKA) are at high risk of post operative venous thromboembolism (VTE). Edoxaban, the oral direct and selective factor Xa inhibitor, is available for preventing VTE after TKA. Recently, patients often take antiplatelet drugs including aspirin for their past illness. In our hospital, patients, in general, undergoing TKA receive edoxaban, but patients with aspirin for past illness receive only aspirin for preventing VTE. The aim of this study was to compare edoxaban and aspirin for preventing VTE in patients undergoing TKA.

Materials and methods

From April 2012 to March 2014, 137 patients underwent primary TKA under general anesthesia with epidural anesthesia or femoral/ sciatic nerve block. Patients were excluded following; (1) renal dysfunction, (2) have taken anticoagulants such as warfarin for past illness. Finally, a total of 120 patients were enrolled.

At the surgery, tourniquet was inflated and mid-vastus approach was used. After prosthesis implantation, tourniquet was deflated and drain tube was inserted. Intra and after operation, an intermittent pneumatic compression device was used.

At postoperative day 2, edoxaban or aspirin started after removal of epidural anesthesia or drainage tube. Ninety-seven patients were assigned to receive edoxaban once daily (group E), and the rest of 23 received aspirin again same as before (group A). Edoxaban were scheduled to continue for 10 days.

Introduction

Measured outcomes from knee joint arthroplasty (TKA) have primarily focused on surgeon-directed criteria, such as alignment, range of motion measured in the clinic, and implant durability, rather than on functional outcomes. There is strong evidence that subjective reporting by patients fails to capture objective real-life function.^1,2 We believe that the recent emphasis on clinical outcomes desired by the patient, as well as the need to demonstrate value, requires a new approach to patient outcomes that directly monitors ambulatory activity after surgery.

We have developed and tested a system that: 1) autonomously identifies patients who are not progressing well in their recovery from TKA surgery; 2) characterizes patient activity profiles; 3) automatically alerts health care providers of patients who should be seen for additional follow-up. We anticipate that such a system could decrease secondary procedures such as manipulation under anesthesia (MUA) and reduce hospital re-admission rates thereby resulting in significant cost savings to the patient, the care providers, and insurers.

Methods

The components of the system include: 1) A sensor package that is mounted correctly in relation to the knee joint (Figure 1a) and is suitable for long term use; 2) An application that runs under the Android operating system to communicate with the sensor and to gather subjective information (pain, satisfaction, perceived stability etc. together with a photograph of the surgical site (Figure 1b); 3) Software to upload the data from the phone to a remote server; 4) An analysis and reporting package that generates, among other metrics, a profile describing the patient's activity throughout the day, trends in the recovery process, and alerts for abnormal findings (Figure 1c). The system was pilot tested on 12 patients (7 females) who underwent TKA. Complete days of data collection were scheduled for each patient every two weeks until 12 weeks, starting during the second week after surgery.

Results and conclusions

The position of the pelvis in the sagittal plane changes significantly between functional activities. The extent of change is specific to each patient. Spinal pathology is a potent “driver” of pelvic sagittal rotation, usually unrecognised on standard radiographs. Pre-operative patient assessment can identify potential orientation problems and even suitability for hard on hard bearings.

Optimal cup orientation is likely patient-specific and requires an evaluation of functional pelvic dynamics to pre-operatively determine the target angles.

Post-operatively this technique can identify patient and implant factors likely to be causing edge loading leading to early failure in metal on metal bearings or squeaking in ceramic on ceramic bearings.

Results and conclusions

The position of the pelvis in the sagittal plane changes significantly between functional activities. The extent of change is specific to each patient.

Spinal pathology can be an insidious “driver” of pelvic rotation, in some cases causing sagittal plane spinal imbalance or changes in orientation of previously well oriented acetabular components.

Squeaking of ceramic on ceramic bearings appears to be multi factorial, usually involving some damage to the bearing but also usually occurring in the presence of anterior or posterior edge loading. Often these components will appear well oriented on standard views [Fig 1].

Runaway wear in hip resurfacing or large head metal-metal THR may be caused by poor component design or manufacture or component malorientation. Again we have seen multiple cases where no such malorientation can be seen on standard pelvic radiographs but functional studies demonstrate edge loading which is likely to be the cause of failure [Fig 2].

Clinical examples of all of these will be shown.

BACKGROUND

There is no report of additional type of bulk bone grafting (Ad-BG) method with impaction morselized bone graft for reconstruction of shallow dysplastic hip in total hip arthroplasty. The purpose of this study was to define the shallow acetabulum and to evaluate the clinical and radiographic results of primary total hip arthroplasty (THA) with Ad-BG method.

MATERIALS and METHODS

With modification of Crowe's classification, shallow dysplasia was defined and classified (Fig. 1). Between October 1999 and August 2008, 120 hips of 302 THAs for dysplastic hip were defined as shallow and Ad-BG was done in 96 hips (80% of shallow hips). For 24 hips with shallow dysplasia, THA were performed by using conventional type of interpositional bulk bone graft (Ip-BG) (8 hips) or without bone graft by using rigid lateral osteophyte. All patients were followed clinically using the Japanese Orthopaedic Association (JOA) score and also Merle d'Aubigne and Postel (M&P) scores in a prospective fashion, and radiographs were analyzed retrospectively. The criteria used for determining loosening were migration or total radiolucent zone between the prosthesis (or bone cement) and host bone. The mean follow-up periods were 8.0 ± 2.3 (5.0–13.5) years.

Purpose

There is a large gap between UKA and TKA in terms of tissue preservation including bone stock and knee ligament. We have recently introduced bicompartmental UKA (Bi-UKA) to fill the gap and achieve more “physiological” knee than TKA. In this study, we report the short-term results of Bi-UKA.

Subjects and Methods

Thirty knees in twenty-nine osteoarthritis patients who underwent Bi-UKA from December 2010 to December 2013 (6 males and 23 females, average age of 75) were clinically and radiologically evaluated with an average observation period of 19 months. The operative indications were (1)confirmed diagnosis of medial and lateral osteoarthritis or osteonecrosis with preserved status of patellofemoral joint; (2)range of knee flexion greater than 110°; (3)flexion contracture less than 20°; (4)clinically stable knee in the frontal and sagittal plane; (5)correctable knee deformity with fine knee congruency. In all cases, fixed type UKA was implanted through a tibia dependent cut using a spacer block. Zimmer Uni and TRIBRID UKA (Kyocera Medical Corporation) were implanted in 18 and 12 cases, respectively.

Objective

The aim of this study was to investigate the clinical results of treatment for patients with periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) in our department.

Patients and Methods

Between April 2004 and March 2014, 9 patients with rheumatoid arthritis (RA) and 6 patients with osteoarthritis (OA) were identified as PJI following TKA and treated in our hospital. We investigated retrospectively the data of each patient, including the clinical background and the peri-operative data as well as the outcome at final follow-up.

Purpose

The purpose of this study was to clarify the relationship between the laxity of surrounding soft tissue and artificial joint kinetics during knee articulation, where total knee arthroplasty had been performed using ceramic LFA artificial knee joints (LFA-TKA below) from Japan Medical Materials (JMM).

Materials Methods

The subjects of the study were 47 knees in 40 LFA-TKA recipients whose cooperation could be obtained. The CR type joint (posterior cruciate retention design) was used in 33 knees in 27 recipients and the PS type joint (posterior cruciate stabilizer design) was used in 14 knees in 13 recipients. OA patients received 30 CR type and 8 PS type joints while RA patients received 3 CR type and 6 PS type joints. For analysis of post surgery knee joint kinetics, using digital fluoroscopy, lateral images were taken of knee motion from a loaded squat position to the erect standing position. Using Knee Motion® software the imaging data was evaluated for 1) femoral rollback, 2) tibial axial rotation patterns, and 3) pivot center position, from analysis of lateral and medial condylar translation (femoral components) at the point of contact with the tibial insert, starting from the extended position. Subsequent imaging under medial-lateral and posteroanterior stress was performed to measure the medial-lateral dihedral angle changes and posteroanterior movement, and the relationship of those factors to the dynamic patterns was evaluated.

Introduction

Genu recurvatum deformities are unusual before total knee arthroplasty (TKA), occurring in less than 1% of patients. The purpose of this study is to evaluate the clinical and radiographic results of primary TKA in patients that had recurvatum deformities before surgery.

Patients and Methods

The inclusion criteria was to have recurvatum deformity over 10 degrees on lateral standing X-ray view. We retrospectively reviewed 22 knees with pre-operative recurvatum deformities, and the incident was 1.0% of all TKAs at our hospital. The etiology of the arthritis was osteoarthritis in 21 knees, of which 3 knees were neuropathic disease, and rheumatoid arthritis in 1 knee. There were 6 men and 16 women, and the average age was 73.3 years (range, 53 to 83 years) at the time of operation. The average follow-up period was 15 months (range, 3 to 81 months). We performed to use medial parapatellar approach and bone cutting was done by measured resection technique. The surgical knacks were resection of less distal femur and proximal tibia bone to make extension gap tightly, additionally decrease the tibial posterior slope. Posterior-stabilizer (PS) implants (NexGen LPS: Zimmer, Bisurface KU4+: JMM) were used in 20 knees and constrained implants (NexGen RH knee: Zimmer, Endo-Model Hinge Knee: Link) were in 2 knees with neuropathic joints.

Background

Massive rotator cuff tears and consequent cuff-deficient arthritis (CTA) of the shoulder can cause severe shoulder dysfunction in the elderly. Reverse total shoulder arthroplasty (RTSA) has been widely used for treatment of CTA in all over the world since its introduction in the 90's. In Japan, however, we have just started to clinically use RTSA from April 2014. In addition, we have only one choice of the implants (Aequalis Reverse, Tornier) currently, and only one size of the base-plate of the glenoid component (29 mm in diameter) is available so far. Japanese, especially elderly people, have generally smaller figure than Caucasians. We are not sure whether the base-plate would fit for the smaller Japanese. The purpose of this study was to measure the size of the glenoids in Japanese using CT images and to examine that they would fit the 29 mm base-plate.

Methods

The shoulders without osteoarthritis of the glenohumeral joint were eligible for the study. The subjects consisted of 30 shoulders including 10 elderly males, 10 elderly females, and 10 younger males, and the mean ages were 73 (range, 63–81), 74 (range, 65–89), and 32 (range, 27–36) years old, respectively. Mean heights and weights were 164 cm (range, 156–179) and 59 kg (range, 49–72), 154 cm (range, 151–161) and 57 kg (range, 48–65), and 173 cm (range, 162–179) and 72 kg (range, 61–100), respectively. CT images with a 0.3 mm slice pitch were used for the analysis. The images were loaded into a DICOM viewer (OsiriX), and a slice for simulated implantation of the base-plate was created using the multi-planar reconstruction (Figure 1), which had 10° of inferior tilt to the glenoid face. The width of the glenoid in the antero-posterior direction was measured at 14 mm above the inferior edge of the glenoid.

Background

The patterns and magnitudes of axial femorotibial rotation are variable due to the prosthesis design, ligamentous balancing, and surgical procedures. LCS mobile-bearing TKA has been reported the good clinical results, however, knee kinematics has not been fully understood. Therefore, we aimed to investigate the effects of the weight-bearing (WB) condition on the kinematics of mobile-bearing total knee arthroplasty (TKA).

Methods

We examined 12 patients (19 knees) implanted with a low contact stress (LCS) mobile-bearing TKA system using a two- to three-dimensional registration technique as previously reported [1]. All 12 patients were diagnosed with medial knee osteoarthritis. The in vivo kinematics of dynamic deep knee flexion under WB and non-WB (NWB) conditions were compared. We evaluated the knee range of motion, femoral axial rotation relative to the tibial component, anteroposterior translation, and kinematic pathway of the femorotibial contact point for both the medial and lateral sides.

Purpose

Surgeons sometimes encounter moderate or severe varus deformed osteoarthritic cases in which medial substantial release including semimembranosus is compelled to appropriately balance soft tissues in total knee arthroplasty (TKA). However, medial stability after TKA is important for acquisition of proper knee kinematics to lead to medial pivot motion during knee flexion. The purpose of the present study is to prove the hypothesis that step by step medial release, especially semimembranosus release, reduces medial stability in cruciate-retaining (CR) total knee arthroplasty (TKA).

Methods

Twenty CR TKAs were performed in patients with moderate varus-type osteoarthritis (10° < varus deformity <20°) using the tibia first technique guided by a navigation system (Orthopilot). During the process of medial release, knee kinematics including tibial internal rotation and anterior translation during knee flexion were assessed using the navigation system at 3 points; (1) after anterior cruciate ligament resection (pre-release), (2) medial tibial and femoral osteophyte removal and release of minimum deep layer of medial collateral ligament (minimum release) and (3) release of semimembranosus (semimembranosus release). In addition, the kinematics after all prostheses implantation (semimembranosus release group) were assessed and compared with those assessed in another 20 patients in which only minimum release was performed (minimum release group).

Background

In total hip arthroplasty (THA), preservation of the short external rotator muscles are considered to be important because they contribute to joint stability and prevent postoperative dislocation. Recently, we reported that there are bony impressions on the greater trochanter that indicate the insertions of the short external rotator tendons. In this study, we reported a method to visualize the bony impressions using preoperative CT images, and evaluate the reliability and accuracy of this method.

Methods

Thirty-three hips from 24 consecutive patients undergoing THA were enrolled. The mean age was 65.3 years. Preoperative diagnoses included hip osteoarthritis in 27 hips, rheumatoid arthritis in 4 hips, idiopathic osteonecrosis in 1 hip, femoral neck fracture in 1 hip. Preoperative CT of the hip region was obtained and three-dimensional (3D) reconstruction of the greater trochanter was performed to visualize the bony impressions, that we called the obturator tendon attachment (OTA), indicating the attachment area of the obturator internus and externus muscles.

Introduction

Our department is responsible specifically for complex cases resulting from trauma. Our experience does not want to add what has been clearly demonstrated by multicenter studies on the efficacy of rivaroxaban but aims to demonstrate how the use of this molecule was effective also in mega-prosthesis and how it has proven to be flexible and safe in dealing with difficulties and surgical complications more common in such difficult cases.

Materials and Methods

From January 2010 to date DVT prophylaxis in THR / TKR and revision was routinely performed with rivaroxaban. To date, in addition to first implant/revision in THR/TKR we treated over 30 cases of large segments replacements (large segments+mega-prosthesis) and we have not highlighted complications attributable to rivaroxaban.

INTRODUCTION

The cost associated with the TKA revision burden is projected to reach 13 billion dollars, annually. Complications reported by post-TKA patients include: pain (44%, multilocational), sensation of instability (21% reason for revision), and joint stiffness (17% reason for revision); problems that may be attributed to soft-tissue imbalance. One of the possible reasons for the substantial prevalence of such complications is the subjectivity associated with defining soft-tissue balance. A priority must be placed on developing new objective methods with which to avoid costly post-operative complications, including the integration of intraoperative sensing technology. The purpose of this evaluation was to report on the disparity between the patient-reported outcomes scores of quantitatively balanced versus unbalanced patients, at 1-year, using a group of 135 multicenter patients.

METHODS

135 prospective patients, from 8 U.S. sites, have had primary TKA performed with the use of intraoperative sensors. Patients were classified by two groups: “balanced” and “unbalanced”. Quantitative “balance” was defined as a mediolateral intercompartmental loading difference of ≤ 15 pounds; all loading exceeding 15 pounds was classified as “unbalanced”. For all patients, the following kinematic data was captured: varus/valgus stability, anteroposterior stability, flexion contracture (if any), extension lag (if any), anatomic alignment, and ROM. Also at each clinical follow-up visit, activity levels and two patient-reported outcomes measures were administered, including: the American Knee Society Score (KSS), and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

Results

From the graphs one can observe significant differences between VV testing at 0 degrees (locked Screw Home), 10 degrees, and 15 degrees of flexion. The shaded area corresponds to the common range of VV stress testing loading pressure, typically less than 35N. The HKA deviates from neutrality no sooner than by the middle of the physiologic test zone. By 35N, the magnitude of the effect is also much less than that observed at 10 and 15 degrees (unlocked from Screw Home). From the kinetic analysis one can also note the significant difference in the High-Low spread throughout the testing range of applied pressure.

If the surgeon tests in the low range of applied loads, he/she may not observe the kinematic joint opening effect. The kinetic effect seems more reliable as sensed loads are detectable earlier on. It is clear however that testing at 10–15 degrees offers a much better sensitivity to the VV laxity or stiffness as exemplified in the bottom portions of the figure. Therefore testing in locked Screw Home full extension may lead to underestimation of the true coronal laxity of the joint.

Introduction

Evaluation of post-operative soft tissue balancing outcomes after Total Knee Arthroplasty (TKA) and other procedures can be measured by stability tests, with Anterior-Posterior (AP) drawer tests and Varus-Valgus (VV) ligamentous laxity tests being particularly important. AP stability can be quantified using a KT1000 device; however there is no standard way of measuring VV stability. The VV test relies on subjective force application and perception of laxity. Therefore we sought to develop and validate a device and method for quantifying knee balancing by analyzing VV stability.

Materials and Methods

Our team developed a Smart Knee Fixture to measure VV angular changes using two dielectric elastomer stretch sensors, placed strategically over the medial and lateral collateral ligaments (see Figure 1). The brace is secured in position with the leg in full extension and the sensors locked with pre-tension. Therefore, contraction and elongation of either sensor is measured and the VV angular deviation of the long axis of the femur relative to that of the tibia is derived and displayed in real time using custom software. EMG muscle activity was previously investigated to confirm there is no resistive activity during the VV test obstructing ligamentous evaluations.

The device was validated in two ways:

A bilateral lower body cadaver specimen, secured in a custom test rig, was used to compare the Smart Knee Fixture's readings to those measured from an optical surgical navigation system. Abduction and adduction force was gradually applied as varus and valgus moments with a wireless hand-held dynamometer up to 50N (19.8Nm) at 0 and 15° flexion.

INTRODUCTION

Patient-reported satisfaction is a critical measure in understanding the clinical success of total knee arthroplasty. Yet, satisfaction levels in TKA patients are generally lower than THA patients; and surgeon-patient agreeability regarding clinical success is typically in discordance. Thus, the purpose of this evaluation was to report on the one-year satisfaction data of a group of sensor-assisted TKA patients, and compare that data to the average satisfaction reported in literature, as measured by a meta-analysis.

METHODS

One hundred and thirty five patients received TKA utilizing intra-operative sensing technology to evaluate soft-tissue balance as part of a prospective multicenter study. Patients were classified by two groups: “balanced” and “unbalanced”. Quantitative “balance” was defined as a mediolateral intercompartmental loading difference of ≤ 15 pounds; all loading exceeding 15 pounds was classified as “unbalanced”. At the one-year follow-up visit, a 7-question patient satisfaction survey was administered. The answering schema of this survey was modeled using a modified five-point Likert scale, ranging from “True” to “False” (or “Very Satisfied” to “Very Dissatisfied,” where appropriate). A meta-analysis of literature was performed and studies selected for inclusion in this analysis were required to meet the following criteria: all patients were in receipt of a primary TKA; satisfaction data was collected post-operatively; and the proportion of patients who were “satisfied” to “very satisfied” was statistically described.

Objective

This study shows the radiographic results of total hip arthroplasty (THA) using the Revelation hip system^® for hip joint disease.

Methods

We performed THA for hip disease using the Revelation Hip System^®. From July 2007 to May 2009, 30cases (35 hips) were available for this study. Radiographic evaluation was performed at the last follow-up. Evaluation items included the presence or absence of subsidence, spot welds, demarcation line, cortical hypertrophy and stress shielding. The stem was designed to be implanted without cement and to be combined to the femur bone at the proximal portion to avoid stress shielding. Zone of Gruen zone 1 was divided into 1A or 1B, above and below the outermost tip of the lateral flare of the stem.

Introduction

Total hip arthroplasty (THA) using short design stem is surging with increasing movement of minimally invasive techniques. Short stems are easier to insert through small incisions preserving muscles. We have used these types of short stems since 2010. Almost all of the patients have shown good clinical results. However, two patients developed fatigue fractures on femurs post operatively. We have reviewed the clinical and radiographic results of these patients.

Patients and methods

From April 2010, we have performed 621 THAs with short design stems, Microplasty^R, Biomet, using a muscle preservation approach, the Direct Anterior Approach (DAA). The age ranged from 31 to 88 years old.

Case1: 56y.o. male, BMI 23.1kg/m². Preoperative diagnosis was bilateral osteoarthritis. Simultaneous THAs were performed on bilateral hips. He was allowed to bear as much weight as he could tolerate using an assistive device immediately after surgery, and followed standard hip precautions for the first 3 weeks. He was discharged from hospital seven days after surgery and returned to his job two weeks after surgery. He noticed sudden left thigh pain three weeks after surgery without any obvious cause. Crutches were recommended to partially bear his weight. Six weeks after surgery, a fracture line became visible on the radiographs and new callus formation also became visible. Three months after surgery, he felt no pain and was able to walk without any crutches.

Case2: 66y.o. female, BMI 27.5 kg/m². Preoperative diagnosis was bilateral osteoarthritis. THAs were performed on the hips at a six month interval. The right hip was operated on first, followed by the left hip. She was discharged from hospital four days after surgery and returned to her job six weeks after surgery. Two months later after left hip surgery, she suddenly felt pain on her left femur without any obvious cause, and was unable to walk. Three weeks later, X-rays showed fatigue fracture lines and new callus formations. After two or three months using crutches, her pain improved and X-rays showed good callus formation and no stem subsidence.

Introduction

The cement mantle thickness for cemented stem during total hip arthroplasty (THA) is different between the complete cement mantle technique and the line-to-line technique. In the line-to-line technique, the size of the rasp is same as that of the stem. We performed THA in321 hipsof 289 patientsusing a new designed triple-tapered polished cemented stem. We investigated the short-term result of these 321 hips clinically and radiographically.

Materials and Methods

From February 2002 to December 2012, 321 THAs were performed in 289 patients with the use oftriple-tapered polished cemented stem (Trilliance). Of these, 306 hips in 274 patients who were followed over 6 months, were evaluated. All THAs were undergone with direct anterior approach in supine position. The third generation cementing technique was standardized. The mean age at surgery was 65.3 years and the mean follow-up period was 24.6 months. Clinical results were evaluated by Japanese Orthopaedic Association (JOA) hip score. Intra-postoperative complications were investigated. Radiographic examinations were performed to investigate the findings of stem loosening, stress shielding, radiolucent line, osteolysis, stem subsidence, stem alignmentand cementing grade on plain radiograph.

Background

Accuracy of implantation is a recognized prognostic factor for the long-term survival of TKA. The purpose of this study was to analyze the accuracy of component orientation and post-operative alignment of the leg following CT-based navigation-assisted TKA and to compare these parameters with those of a conventional surgical technique.

Methods

We retrospectively compared the alignment of 130 total knee arthroplasties performed with a CT-based navigation system with that of 130 arthroplasties done with a conventional alignment guide system. The knee joints were evaluated using full-length weight-bearing antero-posterior and lateral radiographs.

Introduction

Precise implant matching with a resected bony surface is a crucial issue to ensure a successful total knee arthroplasty (TKA). Extremely undersized or oversized components should be avoided. Therefore, we should measure the exact anthropometric data of the resected bony surface preoperatively or intraoperatively. The purpose of this study was to intraoperatively analyze the exact anthropometric proximal tibial data of Japanese patients undergoing TKA and correlate these measurements to the dimensions of current prosthetic systems.

Patients and Methods

Three hundred and seventy-three knees in 299 Japanese patients were included in this study. There were 246 women and 53 men with a mean age of 74 (range: 63–85) years. All TKAs were performed by 3 senior surgeons (TS, AK, and NM). The bone cut in the proximal tibia was made perpendicular to the longitudinal axis of the tibia in the frontal plane. Intraoperative measurements of the proximal tibial cut surface were taken after proximal tibial preparation. Akagi's line (center of the posterior cruciate ligament tibial insertion to the medial border of the patellar tendon attachment) was adopted as the anteroposterior axis line of the proximal tibia. A mediolateral (ML) line was drawn perpendicular to Akagi's line. Then, anteroposterior (AP), lateral anteroposterior (lAP), and medial anteroposterior (mAP) lines were drawn as shown in Figure 1.

Introduction

Using the tibial extramedullary guide needs meticulous attention to accurately align the tray in total knee arthroplasty (TKA). We previously reported the risk for varus tray alignment if the anteroposterior (AP) axis of the ankle was used for the rotational direction of the guide. The purpose of our study was to determine whether aligning the rotational direction of the guide to the AP axis of the proximal tibia reduced the incidence of varus tray alignment when compared to aligning the rotational direction of the guide to the AP axis of the ankle.

Materials and Methods

Introduction

Mobility at insert-tray articulations in mobile bearing knee implant accommodates lower cross-shear at polyethylene (PE) insert, which in turn reduces wear and delamination as well as decreasing constraint forces at implant-bone interfaces. Though, clinical studies disclosed damage due to wear has occurred at these mobile bearing articulations. The primary goal of this study is to investigate the effect of second articulations bearing mobility and surface friction at insert-tray interfaces to stress states at tibial post during deep flexion motion.

Method & Analysis

Figure 1 shows the 3-D computational aided drawing model and finite element model of implant used in this study. LS-DYNA software was employed to develop the dynamic model. Four conditions of models were tested including fixed bearing, as well as models with coefficients of friction of 0.04, 0.10 and 0.15 at tibial-tray interfaces to represent healthy and with debris appearance. A pair of nonlinear springs was positioned both anteriorly and posteriorly to represent ligamentous constraint. The dynamic model was developed to perform position driven motion from 0° to 135° of flexion angle with 0°, 10° and 15° of tibial rotation. The prosthesis components were subjected with a deep squatting force.

Introduction

Knee arthroplasty is an effective intervention for painful arthritis when conservative measures have failed. Despite recent advances in component design and implantation techniques, a significant proportion of patients experience problems relating to the patella-femoral joint (PFJ).

Detailed knowledge of the shape and orientation of the normal and replaced femoral trochlea groove is critical when considering potential causes of anterior knee pain. Furthermore, to date it has proved difficult to establish a diagnosis due to shortcomings in current imaging techniques for obtaining satisfactory coronal plane motion data of the patella in the replaced knee.

The aim of this study was to correlate the trochlea shape of normal and replaced knees with corresponding coronal plane PFJ kinematic data.

Method

Bony and cartilagenous trochlea geometries from 3T MRI scans of 20 normal healthy volunteers were compared with both anatomical and standard total knee replacements (TKR) and patellofemoral joint replacement (PFJR) geometries. Following segmentation and standardized alignment, the path of the apex of the trochlea groove was measured using customized Matlab software. (Fig1).

Next, kinematic data of the 20 normal healthy volunteers (Normal) was compared with that of 20 TKR, and 20 PFJR patients using the validated MAUS^TM system (Motion Analysis and UltraSound) comprising a 12-camera, motion capture system used to capture images of reflective markers mounted on subjects lower limbs and an ultrasound probe. A mapping between the ultrasound image and the motion capture system allows the ultrasound probe to be used to determine the locations of the patella relative to bony landmarks on the femur during a squat exercise.

Introduction

Proper positioning of the baseplate and optimal screw placement are necessary to avoid loosening or failure of the glenoid component in RTSA. Several in vitro and anatomic studies have documented ideal number, size, length and angulation of baseplate screws. However, such fixation can often be tenuous, as the anatomy of scapula bone varies. Furthermore, it can be difficult to identify regions with the best bone stock intraoperatively even though surgeons have an understanding of scapular anatomy with potential screw trajectories in mind. This often leads to variable screw lengths and angulations in the clinical setting. The purpose of this study was to measure optimal screw lengths and angles to reach ideal regions in cadaveric scapulae and to compare the clinical experiences of three surgeons with each other and against a cadaveric model with screw lengths and angulations.

Materials and Methods

Seven cadaveric scapulae were used as the template for optimal screw angulation and length for baseplate implantation. Total 21 cases (seven cases of each 3 surgeons) of reverse total shoulder arthroplasty using the Aequalis®-Reversed shoulder prosthesis (Tornier, France) were included. Measurement of screw angulation was done on the AP and axillary views to account for the superior-inferior and the antero-posterior angulations, respectively. The screw lengths used on each scapula was recorded prior to insertion in cadavers and retrieved from the operative records in clinical cases. Screws directed anteriorly and superiorly were recorded as positive values while posteriorly and inferiorly directed screws were designated negative values. The significant differences in degrees of screw angulation and screw lengths among the 3 surgeon groups were calculated using the ANOVA, with the p value at 0.05. The Mann-Whitney U test was performed to evaluate the cadaver group against the surgeon groups.

Purpose

In this study, we report the clinical results of medial UKA in combination with patellofemoral arthroplasty (MUKA/PFA) in 7 cases of bicompartmental osteoarthritis.

Subjects and Methods

Seven patients who received MUKA/PFA between June 2011 and April 2012 were included into the study. There were 1 male and 6 females with an average age of 77 years at time of operation. All those patients were suffering end stage osteoarthritis of both medial and patellofemoral compartments, with obvious clinical and radiological findings. The average follow-up period was 7 months. Patients were clinically examined including JOA score and range of motion (ROM) and radiographs were evaluated.

Objective

Tibia vara seen in Japanese patients reportedly influences the tibial component alignment when performing TKA. However, it is unclear whether tibia vara affects the component position and size selection. We therefore determined (1) the amount of medial tibial bow, (2) whether the tibia vara influences the aspect ratio of the tibial resected surface in aligning the tibial component with the tibial shaft axis (TSA), and (3) whether currently available tibial components fit the shapes of resected proximal tibias in terms of aspect ratio.

Material and Methods

The study was performed using CT data from 90 lower limbs in 74 Japanese female patients with primary varus knee OA, scheduled for primary TKAs between January 2010 and March 2012. We measured the tibia vara angle (TVA; the angle between the TSA and the tibial mechanical axis), proximal varus angle (PVA; angle between the TSA and the line connecting the center of the tibial eminence and the center of the proximal 1/3 of the tibia) using three-dimensional preoperative planning software [Fig.1]. Then the mediolateral and middle AP dimensions of the resected surface when the tibial component was set so that its center aligned with the TSA was measured. We determined the correlations of the aspect ratio (the ML dimension divided by the AP dimension) of the resected surface with TVA or PVA and compared the aspect ratios to those of five prosthesis designs.

Background

Flexion-extension gap balancing is recognized as an essential part of total knee arthroplasty (TKA). The gap is often evaluated using spacer blocks, laminar spreader, or tensor device. The evaluation of gap balancing with the patella in the reduced position is more physiological and reproducible than with patellofemoral (PF) joint everted. However, in the knee with a reduced PF joint, it is difficult to comprehend the anteroposterior position of the tibia to the femur. So, we developed a new tensor to lift up the tibia ahead and fix the anteroposterior position of the tibia to the femur with the PF joint reduced [Fig.1].

Purpose

To investigate how accurate the extension and flexion gaps would be measured by comparing our new tensor with the conventional tensor which could not fix the position of the tibia to the femur.

Introduction

Excellent long-term survival rates associated with the absence of stem subsidence have been achieved with total hip arthroplasty (THA) using femoral components cemented line-to-line (“French Paradox”). Recently, short stems have been introduced in order to preserve diaphyseal bone and to accommodate to minimal invasive THA and a variety of clinical situations. The aim of the current study was to quantify the rotational and tilting stability of a Kerboull stem of varying length after line-to-line cementation using a validated in-vitro model.

Materials & methods

The femoral component made of M30NW stainless steel was derived from the original Kerboull stem. It had a double taper, a highly polished surface, and a quadrangular cross-section. Four stem lengths were designed from the original length with a distal reduction of 6, 12, 17 and 22%, whereas the proximal body geometry of the implant remained unaffected. For each stem length, five specimens were implanted into a non-canal synthetic femoral model. The femoral preparation was performed in order to obtain rotational and tilting stability of the stem prior to the line-to-line cementation. Spatial micro-motions of the specimens were investigated using a validated rotational measuring set-up. In addition, in a second separate step, the specimens were exposed to a ventro-dorsal moment to mimic varus-valgus moment. Statistical analysis was performed using ANOVA with Fisher PLSD.

Introduction

The wear performances of polyethylene in THA are influenced at a great extent by the manufacturing process. During the past decade, highly cross-linked materials have been developed with encouraging results in terms of wear, whereas another body of the literature has indicated potential catastrophic failures related to reduced fatigue properties and oxidation due to lipids adsorption and fatigue mechanism. Also, each of the materials available on the market has its own processing characteristics. Therefore, a specific evaluation is necessary for each of them. The aim of this retrospective study was to evaluate the wear properties of metal-back sockets using a first generation highly cross-linked PE in a consecutive series of primary THAs.

Materials

Between August 2005 and December 2007, 80 patients (80 hips) with a mean age of 62.7 ± 8.9 years were included. All patients had a 28mm CoCr femoral head articulating with a highly cross-linked insert (Highcross®, Medacta SA) that was 100 Mrads gamma radiated, remelted at 150°C, and ethylene oxide sterilized. The primary criterion for evaluation was linear head penetration measurement using the Martell system, performed by an investigator trained to this technique. Also, steady state wear was calculated. Functional results were evaluated according to WOMAC score.

Introduction

Cementless femoral hip stems crucially depend on the initial stability to ensure a long survival of the prosthesis. There is only a small margin between obtaining the optimal press fit and a femoral fracture. The incidence of an intraoperative fracture is reported to be as high as 30% for revision surgery. The aim of this study is to assess what information is contained in the acoustic sound produced by the insertion hammer blows and explore whether this information can be used to assess optimal seating and warn for impeding fractures.

Materials and Methods

Acoustic measurements of the stem insertion hammer blows were taken intra-operatively during 7 cementless primary (Wright Profemur Primary) and 2 cementless revision surgeries (Wright Profemur R Revision). All surgeries were carried out by the same experienced surgeon. The sound was recorded using 6 microphones (PCB 130E2), mounted at a distance of approximately 1 meter from the surgical theater. The 7 primary implants were inserted without complication, 1 revision stem induced a fracture distally during the insertion process. Two surgeons were asked to listen independently to the acoustic sounds post-surgery and to label the hits in the signal they would associate with either a fully fixated implant or with a fracture sound. For 3 out of 7 primary measurements the data was labeled the same by the two surgeons, 4 were labeled differently or undecided and both indicated several hits that would be associated with fracture for the fractured revision case. The acquired time signals were processed using a number of time and frequency domain processing techniques.

Introduction

UHMWPE particle-induced osteolysis is one of the major causes of arthroplasty revisions. Recent in vitro findings have suggested that UHMWPE wear particles containing vitamin-E (VE) may have reduced functional biologic activity and decreased potential to cause osteolysis (Bladed C. L. et al, JBMR B 2012 and 2013). This is of significant importance since VE-stabilized cross-linked UHMWPEs were recently introduced for clinical use, and there is no in vivo data determining the effects of wear debris. In this study we hypothesized that particles from VE-stabilized, radiation cross-linked UHMWPE (VE-UHMWPE) would cause reduced levels of osteolysis in a murine calvarial bone model when compared to virgin gamma irradiated cross-linked UHMWPE.

Methodology

Study groups were the following: 1). Radiation cross-linked VE-UHMWPE (0.8% by weight) diffused after 100 kGy; 2). Radiation cross-linked virgin UHMWPE (virgin UHMWPE); 3). Sham controls. Particle generation and implantation: UHMWPE was sent to Bioengineering Solutions (Oak Park, IL) for particle generation. After IACUC approval, C57BL/6 mice (n=12 for each group) received equal amount of particulate debris (3mg) overlying the calvarium and were euthanized after 10 days. Micro-CT scans: High resolution micro-CT scans were performed using a set voltage of 70 kV and current of 70 µA. Topographical Grading Scale: Each calvarial bone was blindly scored using the following scale: 0=No osteolysis, defined as intact bone; 1=Minimal osteolysis, affecting 1/3 or less of the bone area; 2=Moderate osteolysis, affecting at least 2/3 of the bone area; 3=Severe osteolysis, defined as completely osteolytic bone. Histology: H&E and TRAP staining was done on tissue to confirm micro-CT findings and quantify osteoclasts. Statistical Analysis: Inter-rater analysis was done using Cohen's kappa analysis. An inter-rater coefficient >0.65 was considered as high inter-rater agreement. Comparison between groups was made using one-way ANOVA with post hoc Bonferroni correction for multiple comparisons. Correlations are reported as Spearman's rho. P-value<0.05 was considered statistically significant.

Introduction

In Cruciate Retaining (CR) Total Knee Arthroplasty (TKA), the Posterior Cruciate Ligament (PCL) is preserved but the Anterior Cruciate Ligament (ACL) is sacrificed. In contemporary CR implants, failure to substitute for ACL function causes abnormal knee motion, with the femur being located excessively posterior on the tibia in full extension (Fig. 1), and sliding forward during early flexion. To address this kinematic abnormality, we developed an ACL Substituting Cruciate Retaining (ASCR) TKA implant that substitutes for the absent ACL, while preserving the native PCL. The ASCR tibia includes an ACL substituting post that engages the intercondylar notch of the femoral component in low flexion to act for the missing ACL (Fig. 1). With continued flexion, the post disengages from the femoral component and the native PCL guides further motion of the femur (femoral rollback). Thus the ACL substituting post mimics the native ACL function. The hypothesis of this study was that the ASCR implant can address the abnormal femoral sliding seen in contemporary CR implants.

Methods

The kinematics of an ACL-preserving implant, the ASCR implant, and a contemporary CR implant during deep knee bend was simulated using LifeMOD KneeSIM software (Fig. 2). The PCL was preserved in all implants. Anteroposterior motion of the femoral condyles relative to the tibia was measured. The implants were mounted on an average knee model created from Magnetic Resonance Imaging (MRI) of 40 healthy knees. The medial and lateral collateral ligaments, PCL, ACL (for ACL-preserving implant), quadriceps mechanism, and capsular tension were modeled. The soft-tissue insertions were obtained from the average knee model, and the mechanical properties were obtained from literature.

Introduction

Dual Mobility (DM) implants have gained popularity for the treatment and prevention of hip dislocation, with increased stability provided by a large diameter mobile insert. However, distal regions of the insert may impinge on soft tissues like the iliopsoas, leading to groin pain. Additionally, soft-tissue impingement may trap the mobile insert, leading to excessive loading of the insert rim from engagement with the femoral neck and subsequent intra-prosthetic dislocation. To address this, an Anatomically Contoured Dual Mobility (ACDM) insert with a soft-tissue friendly distal geometry was developed (Fig.1). Previously, the ACDM insert was shown to maintain the femoroacetabular contact area and joint stability of a conventional DM insert [Duffy et al. BJJ 2013, 95-B:34, p298; Zumbrunn et al. BJJ 2013, 95-B:34, p605]. The goal of this study was to utilize cadaver specimens to verify whether the ACDM insert could reduce soft-tissue impingement relative to a conventional DM insert.

Methods

Fluoroscopic imaging was used to evaluate soft-tissue interaction with ACDM and conventional DM inserts in four cadaver hips (Fig. 2). A metal wire was sutured to the deep fibers of the iliopsoas muscle/tendon, and metal wires were embedded in the inner head and the mobile insert for fluoroscopic visualization. All soft tissue except the anterior hip capsule and iliopsoas were removed, and a rope was attached to the iliopsoas to apply tension along its native orientation. A femoral stem and a DM acetabular shell were implanted sothe ACDM or conventional DM inserts, together with the inner heads, could be inserted. Fluoroscopic images of the hip joint were taken at maximum hyperextension, 0°, 15° and 30° hip flexion with the insert positioned in neutral and anteverted orientations (Fig. 2). Neutral orientation corresponded to the insert axis parallel to the femoral neck, while anteverted orientation corresponded to a flexed insert that contacted the femoral neck posteriorly.

Introduction

Radiation cross-linked UHMWPEs were developed to address osteolysis-induced joint arthroplasty failure by improving wear resistance and reducing associated particulate debris. Introduced clinically fifteen years ago, they are the primary bearing surface in use with excellent clinical outcomes and wear resistance. First generation materials sought to maintain oxidative stability by reducing or eliminating free radicals through thermal treatments, while second generation aimed to further balance oxidation resistance and improve mechanical properties through sequential irradiation and annealing or the incorporation of an antioxidant. Recent reports have identified lipid absorption and cyclic loading as potential in vivo oxidation-inducing mechanisms. In this on-going retrieval study, we report on the current status of oxidative stability in these two generations of UHMWPE bearings.

Materials & Methods

Six types of highly cross-linked UHMWPE hip and knee bearings (Table 1) were surgically-retrieved and collected under IRB approval. Standard material analysis was performed on cross-sections of loaded and unloaded bearing surfaces of the components. Thin sections (150 µm thickness) were extracted in boiling hexanes under reflux for 16 hours followed by vacuum drying for 24 hours. FTIR was used to evaluate oxidation and calculated from post-hexane absorbance spectra by normalizing the area under 1740 cm⁻¹ (1680–1780 cm⁻¹) to the area under 1370 cm⁻¹ (1330–1390 cm⁻¹), per ASTM F2102-13. Gravimetric swelling of regional cross-sectional blocks (1–2 mm³) for 2 hours in 130°C boiling xylenes was used to assess cross-link density, per ASTM 2214.

Introduction

Appropriate osteotomy alignment and soft tissue balance are essential for the success of total knee arthroplasty (TKA). The management of soft tissue balance still remains difficult and it is left much to the surgeon's subjective feel and experience.

We developed an offset type tensor system for TKA. This device enables objective soft tissue balance measurement with more physiological joint conditions with femoral trial component in place and patello-femoral (PF) joint reduced. We have reported femoral component placement decreased extension gap.

The purpose of the present study was to analyze the influence of femoral component size selection on the decrease of extension gap in posterior-stabilized (PS) TKA.

Material & Method

120 varus type osteoarthritic knees implanted with PS TKAs (NexGen LPS flex: Zimmer) were subjected to this study. All TKAs were performed using measured resection technique with anterior reference.

The femoral component size was evaluated intra-operatively using conventional femoral sizing jig. The selected femoral component size was expressed by the antero-posterior (AP) size increase (mm) comparing to that of original femoral condyles. Gap measurements were performed using a newly developed offset type tensor device applying 40lbs (178N) of joint distraction force. Firstly, conventional osteotomy gaps (mm) were measured at extension and flexion. Secondary, component gaps (mm) after femoral trial placement with PF joint reduced were evaluated at 0° and 90° of knee flexion.

To compare conventional osteotomy gaps and component gaps, estimated extension and flexion gaps were calculated by subtracting the femoral component thickness at extension (9mm) and flexion (11mm) from conventional osteotomy gaps respectively. The decrease of gap at extension and flexion were calculated with estimated gaps subtracted by component gaps. The simple linear regression analysis was used to evaluate the influence of selected femoral component size on the decrease of gap after femoral component placement.

Introduction

Cup malposition in hip arthroplasty and hip resurfacing is associated with instability, accelerated wear, and the need for revision. A recent study measuring cup orientation on conventional radiodiographs demonstrated an incidence of cup malpositioning of 50% according to the safe zone that they defined 1,2. A prior study of 105 conventionally placed cups using CT demonstrated a cup malpositioning incidence of 74%3. The current study similarly assesses the variation in cup position using conventional techniques as measured by CT.

Methods

CT studies of 123 hips in 119 patients with total hip arthroplasties performed using conventional techniques were used for this study. The indications for the CT studies were for CT-based surgical navigation of the contralateral side or for assessment of periprosthetic osteolysis. An application specific software modules was developed to measure cup orientation using CT (HipSextant Research Application 1.0.13 Surgical Planning Associates Inc., Boston, Massachusetts). The cup orientation was determined by first identifying Anterior Pelvic Plane Coordinate system landmarks on a 3D surface model. A multiplanar reconstruction module then allowed for the creation of a plane parallel with the opening plane of the acetabulum. The orientation of the cup opening plane in the AP Plane coordinate space was calculated according to Murray's definitions of operative anteversion and operative inclination. Since these studies including images through the femoral condyles, femoral anteversion could be measured on these hips as well (Osirix v5.6, Pixmeo SARL, Bernex, Switzerland).

Introduction

Studies show that cup malpositioning using conventional techniques occurs in 50 to 74% of cases defined. Assessment of the utility of improved methods of placing acetabular components depends upon the accuracy of the method of measuring component positioning postoperatively. The current study reports on our preliminary experience assessing the accuracy of EOS images and application specific software to assess cup orientation as compared to CT.

Methods

Eighteen patients with eighteen unilateral THA had pre-operative EOS images were obtained for preoperative assessment of leg-length difference and standing pelvic tilt. All of these patients also had preoperative CT imaging for surgical navigation of cup placement. This allows us to compare cup orientation as measured by CT to cup orientation as measured using the EOS images.

Application specific software modules were developed to measure cup orientation using both CT and EOS images (HipSextant Research Application 1.0.13 Surgical Planning Associates Inc., Boston, Massachusetts). Using CT, cup orientation was determined by identifying Anterior Pelvic Plane coordinate system landmarks on a 3D surface model. A multiplanar reconstruction module allows for creation of a plane parallel with the opening plane of the acetabulum and subsequent calculation of plane orientation in the AP Plane coordinate space according to Murray's definitions of operative anteversion and operative inclination.

Using EOS DICOM images, spatial information from the images were used to reconstruct the fan beam projection model. Each image pair is positioned inside this projection model. Anterior Pelvic Plane coordinate points are digitized on each image and back-projected to the fan beam source. Corresponding beams are then used to compute the 3D intersection points defining the 3D position and orientation of the Anterior Pelvic Plane. Ellipses with adjustable radii were then used to define the cup border in each EOS image. By respecting the fan beam projection model, 3D planes defining the projected normal of the ellipse in each image are computed. 3D implant normal was estimated by determining 3D plane intersection lines for each image pair.

Implant center points are defined by using the back-projected and intersected ellipse center beams in the image pairs (Figure 1).

INTRODUCTION

Cup malpositioning remains a common cause of dislocation, wear, osteolysis, and revision. The concept of a “Safe Zone” for acetabular component orientation was introduced more than 35 years ago¹. The current study assesses CT studies of replaced hips to assess the concept of a safe zone for acetabular orientation by comparing the orientation of acetabular components revised due to recurrent instability and to a series of stable hip replacements.

METHODS

Cup orientation in 30 hips revisedin 27patients for recurrent instability was measured using CT. These hips were compared to a group of 115 stable hips measured using the same methods. Femoral anteversion in the stable hips was also measured. Images to assess femoral anteversion in the unstable group were not available. An application specific software modules was developed to measure cup orientation using CT (HipSextant Research Application 1.0.13 Surgical Planning Associates Inc., Boston, Massachusetts). The cup orientation was determined by first identifying Anterior Pelvic Plane Coordinate system landmarks on a 3D surface model. A multiplanar reconstruction module then allowed for the creation of a plane parallel with the opening plane of the acetabulum. The orientation of the cup opening plane in the AP Plane coordinate space was calculated according to Murray's definitions of operative anteversion and operative inclination². Both absolute cup position relative to the APP and tilt-adjusted cup position³ were calculated.

INTRODUCTION

Young patients (< 50 years old) have been reported to have a higher risk of revision following total hip arthroplasty (THA) than older patient cohorts, possibly to due higher activity, a higher incidence of deformity and greater probability of prior surgery. Ceramic-on-ceramic bearing surfaces have been proposed for use in young and active individuals due to their low wear, low risk of adverse biologic reaction, and long-term survivorship. We assessed the clinical results and long-term survivorship of uncemented ceramic-on-ceramic THA in a young patient population.

METHODS

Between August 1999 and December 2007, 220 total hip arthroplasties in 191 patients under 50 years of age at the time of surgery were performed using alumina ceramic-ceramic bearings as part of a prospective, non-randomized study. All patients received uncemented acetabular components with flush-mounted acetabular liners using an 18 degree taper, and uncemented femoral components. The average patient age at the time of surgery was 42.1 ±7.2 years (range: 17.4 years to 49.9 years), and the average time to follow-up was 10.1 ±2.4 years (range: 4.2 years to 15.2 years). We evaluated implant-related complications and performed Kaplan-Meier analyses to determine survivorship of the THA components with revision for any reason as the endpoint.

BACKGROUND

Cup malpositioning remains a common cause of dislocation, wear, osteolysis, and revision. The concept of a “Safe Zone” for acetabular component orientation was introduced more than 35 years ago. The current study assesses CT studies of replaced hips to assess the concept of a safe zone for acetabular orientation.

PURPOSE

We assessed the orientation of acetabular components revised due to recurrent instability and compared the results to a series of stable hip replacements.

Aim

To asses the accuracy of total knee replacements performed using CT based patient specific instrumentation by postoperative CT scan.

Method

Approval from the Ethics Committee at The University of New South Wales Sydney Australia was granted prior to commencement of this study. 50 patients who had undergone total knee replacement (Evolis, Medacta International) using CT-based patient specific instrumentation (MY KNEE Medacta International) were assessed postoperatively using a CT scan and a validated measurement technique. The mechanical axis of the limb in the coronal plane, the varus/valgus positioning of the femoral component, the varus/valgus positioning of the tibial component, the flexion/extension of the posterior flange of the femoral component and the posterior slope of the tibial base plate were recorded. These results were then compared to each patient's preoperative planning. The percentage of patients found to be within 3 degrees of planned alignment were calculated. This represents the most comprehensive prospective study to utilize CT assessment of postoperative alignment in patient specific instrumentation. All other studies, to our knowledge have utilized scanograms or scout images and not full CT protocol as performed in this study.

Introduction

The effect of each step of medial soft tissue release was assessed taking the expansion strength and patellar condition into account in five fresh frozen normal cadaver specimens.

Methods

In each cadaver specimen, only proximal tibia was cut. Then, ACL was cut, and deep MCL fiber was released. This condition was set as “the basic”. Joint gap distance and angle were measured at full extension, 30°, 60°, 90°, 120° flexion and in full flexion. The measurement was firstly done with the standard tensor/balancer with the patella everted, and the next with the offset tensor/balancer with the patella reduced. The torque of 10, 20 and 30 inch-pounds were applied through the specialized torque wrench. After the measurement in “the basic”, PCL, MCL superficial fibres, pes anserinus and semi-membranosus were released step by step. Measuring the joint gap distance and angle with the same scheme above were conducted after the each step.

Introduction

Macrophages phagocytes implant wear debris and produce various cytokines to evoke inflammation and periprosthetic osteolysis of aseptic loosening. It had been reported that expression of Toll-like receptor (TLR) 2 and other TLRs increased in periprosthetic tissues of aseptic loosening. Pathogen-associated molecular patterns (PAMPs) and damaged-associated molecular patterns (DAMPs) have been known as ligands of TLRs and considered to be involved in the osteolytic reactions via TLRs. Another type of immune sensors, nucleotide-binding and oligomerization domain (NOD)-like receptors (NLR) with a pyrin domain 3 (NLRP3) can also recognize PAMPs and DAMPs as their lignds, which has been presumed to participate in the local host response of macrophage cascade via phagocytosis of implant wear particles. However, the contribution of NLRP3 in periprosthetic tissues of aseptic loosening and the correlation between TLR2 and NLRP3 are still unclear.

Materials and methods

TLR1, TLR2, TLR6, NLRP3, TNF-α and IL-1β of macrophages in aseptic loose periprosthetic tissues were immnohistorically evaluated and compared to osteoarthritic synovium. RAW264.7 cells, macrophagic cell line, were stimulated by titanium particles (Ti) and lipoteichoic acid (LTA)-coated Ti. The celluar reaction associated with TLR2 and NLRP3 and the correlation of them were analyzed at mRNA expression levels with small-interfering RNA of Irak2, one of adaptor molecules in TLR2 cascades.

Introduction

Knee osteoarthritis (OA) is a major contributor to disability in seniors and affecting millions of people around the world. Its main problem and the biggest factor in the disability of patients is pain. Pain renders patient inactive and develops lower extremity muscle wasting and worsens patient status adversely. However no radical solution existed until now. Recently I discovered a very valid manipulative technique (Squeeze-hold) for OA knee. This study presents the one-year follow-up data (three cases) by this treatment.

Methods

Back ground

In 1970's, condylar type knee prosthese with anatomic design appeared, however, joint flexion was not satisfactory. Y/S II total knee arthroplasty (TKA) was developed to obtain deep flexion together with bilateral ligament balance in 1980. The articular surface of the tibial component was flattened to permit femoral shift posteriorily during knee flexion. Medial and lateral soft tissue release was determined by a unique ligament tensor both at flexion and extension. A metal tray was embedded in polyethylene, which had a shape of glasses frame. Though the usage of Y/SII TKA was finished in 1984, we here studied its long term surgical results using the Kaplan-Meyer method.

Study design

From 1988 to 1991, 122 knees were replaced by Y/SII TKA in 81 patients with rheumatoid arthritis (RA). Among them, 24 joints in 12 patients were examined directly. The average age of follow-up was 19.5 years. The survival rate was investigated according to medical records.

Introduction

On the basis of a proposal by Noble, the marrow cavity form can be classified into three categories: stovepipe, normal, and champagne-fluted. In the present study, three typical finite element femoral models were created using CT data based on Noble's three categories. The purpose was to identify the relationship of stress distribution of the surrounding areas between femoral bone marrow cavity form and hip stem. The results shed light on whether the distribution of the high-stress area reflects the stem design concept. In order to improve the results of THA, researchers need to consider the instability of a stem design based on the pressure zone and give feedback on future stem selection.

Methods

To develop finite element models, two parts (cortical bone and stem) were constructed using four-node tetrahedral elements. The model consisted of about 40,000 elements. The material characteristics were defined by the combination of mass density, elastic coefficient, and Poisson's ratio. Concerning the analysis system, HP Z800 Workstation(HP, Japan) was used as hardware and LS-DYNA Ver. 971 (Livermore Software Technology Corporation, USA) as software. The distal end of the femur was constrained in all directions. On the basis of ISO 7206 Part 4,8 that specifies a method of endurance testing for joint prostheses, the stem was tilted 10°, and a 500 N resultant force in the area around the hip joint was applied to the head at an angle of 25° with the long axis. Automatic contact with a consideration of slip was used. Von Mises stress during a 1.0 s period after loading was analyzed, and stress distribution in the stem and its maximum value were calculated.

Introduction

LCS total knee arthroplasty was used in many nations worldwide. This implant's features are not only mobile bearing but also has very unique concepts of mechanism.

Meniscal bearing (MB) is a one of the types of implant. 2 separate bearings move on the tibia plate. This implant has been known to need revision in cases of over ten years. F.F. Buechel¹⁾ reported a 5% revision rate at an average of 10.1 years. On the other hand, another type of implant, which is a rotating platform bearing LCS, had only 1.2% at an average of 9.9 years.

Patients and Methods

We used the meniscal bearing type LCS (MB-LCS) 289 knees from May 1995 to Dec. 2005. All cases were supervised by chief surgeon Makoto Kobori. He reported on the long term follow up of LCS until 2006. There were 18 cases revision of the MB-LCS (revision rate 6%) and in all cases only the meniscal bearings were replaced.²⁾ We followed further until April 2014.

Background

Septic knee arthritis is one of the most serious complications after total knee arthroplasty (TKA), and the effectiveness of its treatment affects the patient's quality of life. In our super-aging society, the frequency of TKA in the elderly, often combined with various comorbidities, is increasing. Careful management should be considerd during the management of septic arthritis after TKA in these patients.

Purpose

To analyze the clinical features and outcomes of septic arthritis after TKA in our institution.

Introduction

Osteolysis caused by wear of the ultrahigh molecular weight polyethylene (UHMWPE) often leads to failure. Cross-linking improves wear, but also produces residual free radicals that decrease oxidative stability. In vitro studies have shown that the anti-oxidative properties of vitamin E UHMWPE stabilize free radicals while retaining the physical and chemical properties of UHMWPE. The porous surface of the Regenerex™ shell was developed for improved bone in-growth fixation. The increased porosity of the Regenerex™ shell promotes early bony in-growth with the goal of greater long-term stability. The purpose of this study was to evaluate vitamin E infused polyethylene (VEPE) wear and stability of acetabular and femoral components using RSA.

Methods

58 patients (64 observed hips), all with osteoarthritis, gave informed consent to participate in a 5 year RSA study. Each patient received a VEPE liner, a Regenerex™ acetabular shell, and an uncemented stem with either a 32mm or 36 mm cobalt chrome femoral head. Tantalum beads were inserted into the VEPE, the pelvic and the femoral bone to measure head penetration into the polyethylene, and shell and stem stability over time, using RSA. RSA radiographs were scheduled immediately postoperatively (up to 6 weeks) and 6 months, 1, 2, 3, and 5 years after surgery. The Wilcoxon signed-ranks nonparametric test was used to determine if changes in penetration or migration were significant over time at p≤0.05.

Introduction

RSA is widely accepted as a precise method to asses wear and migration early in the postoperative period. In traditional RSA, one segment defines both the acetabular shell and the polyethylene liner. However, inserting beads into the liner permits employment of the shell and liner as two separate segments, thus enabling distinct analysis of the precision of three measurement methods in determining wear and acetabular shell migration. The purpose of this in vivo follow-up study was to determine if assigning the shell and liner as one combined, or two individual segments affected the precision of RSA measurements of wear and shell stability.

Methods

The UmRSA program was used to analyze the double examinations of 51 hips to determine if there was a difference in precision among 3 measurement methods: the shell only, the liner only, and the shell + liner combined segment. Tantalum beads were inserted into the liner and pelvic bone surrounding the shell intraoperatively for the purpose of RSA. Polyethylene wear was measured using point motion of the center of the head with respect to 3 different segments: 1) liner only, 2) the shell only and, 3) shell + liner segment. Cup stability was measured by segment motion comparing the stable pelvic segment to 1) the liner segment, 2) the shell only segment, and 3) the shell + liner segment. The Wilcoxon paired signed-ranks test was used to determine differences in condition number and bead counts among the 3 measurement methods (p ≤0.05).

Introduction

Rivaroxaban, an oral factor Xa inhibitor, has been approved by USFDA for prophylaxis of deep vein thrombosis (DVT) and pulmonary embolism (PE) in hip and knee arthroplasties. Its indication in hip fracture surgery has been recently recommended in Asian venous thromboembolism (VTE) guidelines. Phase II dose-ranging study demonstrated that 5 mg rivaroxaban is as effective as enoxaparin for VTE prophylaxis with lower incidence of bleeding complication than the recommended 10 mg dose. Rivaroxaban is recommended to be given 6–8 hours after operation. However, many surgeons are hesitated to follow this guideline since it might increase post-operative blood loss and wound complication. Elderly patients, such as hip fracture patients, are generally at more risk of bleeding and wound complications. These patients may benefit from using the delayed and reduced-dose regimen.

Methods

Since July 2011, all eligible hip fracture patients treated by single group of surgeons were given 5mg daily dose of rivaroxaban for VTE prophylaxis. Initial dose of rivaroxaban was given after drain had been removed (24–36 hours post-operatively) and continued for 14 days. Inclusion criteria are femoral neck fracture or intertrochanteric fracture in patients age 60 and over. Exclusion criteria are pathologic fracture, reoperation for failed fixation, chronic anticoagulant therapy, and allergy to rivaroxaban. Criteria by Aniwan and Rojnackarin were used for clinical diagnosis of DVT and PE. Suspected case of DVT and PE were sent for confirmation with Doppler U/S and Pulmonary Artery CT scan, respectively. All bleeding and wound complications were recorded. Numbers of blood transfusion were also recorded. Patients were followed for at least 6 weeks, all complications were recorded.

Introduction

In comminuted intertrochanteric fractures, various operative options have been introduced. The purpose of this study was to determine whether there were differences in clinical and radiologic outcomes among bipolar hemiarthroplasty(BH), compression hip screw(CHS) and proximal femur nail antirotatory(PFNA) in treating comminuted intertrochanteric fractures(AO type, A2(21, 22, 23))

Materials and Methods

We retrospectively evaluated total 150 patients(BH:50, CHS:50, PFNA: 50) who were operated due to intertrochanteric fractures from March 2010 to Dec 2012 and were older than 65 years at the time of surgery. We compared these three groups for radiologic and clinical outcomes at 12 months postoperatively, including Harris hip score, ability of ambulation(Koval stage), visual analogue scale and radiologic limb length discrepancy(shortening). Landmark and radiologic length was checked.

–A: postoperative length

Materials and Methods

Between 2002 and 2012, the senior authors performed 20 cementless THA in 16 patients who had followed after TRO. The operation time, blood loss, post-operative X-ray findings, and overall clinical results (JOA score) were investigated. These data were compared with simple THA following 10 years.

Results

A mean duration between TRO and THA was 58 month, a mean age at the time of THA was 52.1 years old. Pre-operative classification was all Type C and stage 2 or higher stage. Osteonecrosis of femoral head before THA was mean 56.2%. Operation time was 160 minutes, and mean blood loss was 764 g. In post-operative X-ray findings, a cup was at original anatomy in place in all cases. There is a tendency of slight varus femoral stem position after THA following TRO. The JOA score was improved from 42.1 to 74.2.

Purpose

Chronic massive rotator cuff tears are challenging to repair completely because of the development of tendon retraction with inelasticity, muscle atrophy and fatty infiltration. The objective of this study was to investigate the clinical outcome and MRI findings after arthroscopic superior capsule reconstruction (ASCR) for symptomatic irreparable rotator cuff tears.

Methods

From 2011 to 2013, 12 shoulders in 12 consecutive patients (mean, 70.8 years) with irreparable massive rotator cuff tears underwent ASCR using fascia lata. We used suture anchors to attach the graft medially to the glenoid superior tubercle and laterally to the greater tuberosity as same technique by Mihata et al. We added side-to-side sutures between the graft and infraspinatus tendon and between the graft and residual anterior supraspinatus/subscapularis tendon to improve force coupling. Physical examination, clinical rating system, and magnetic resonance imaging (MRI) were performed before surgery; at 6 and 12 months after surgery; and 6 months thereafter. Average follow-up was 19.1 months (12 to 28 months) after surgery. We assessed patients preoperatively by using the scoring systems of the shoulder index of the American Shoulder and Elbow Surgeons (ASES), the Japanese Orthopaedic Association, and the University of California, Los Angeles.

Introduction

Total knee arthroplasty (TKA) is a well-established procedure associated with excellent clinical results. We have previously reported that intraoperative knee kinematics correlate with the clinical outcome in mobile bearing TKA. In addition, the intraoperative knee kinematics pattern does not correlate with the degree of preoperative knee deformity in mobile bearing TKA. However, the relationship among preoperative knee deformity, intraoperative kinematics and clinical outcome in fixed bearing TKA has been unknown. The purpose of this study is to compare the relationship among preoperative knee deformity, knee kinematics after fixed bearing TKA and the clinical outcome including the subjective outcomes evaluated by the new knee society score (KSS).

Materials and Methods

A cross-sectional survey of thirty-five consecutive medial osteoarthritis patients who had a primary TKA using a CT-based navigation system was conducted. All knees had a Kellgren-Lawrence grade of 4 in the medial compartment and underwent a primary posterior stabilized TKA (Genesis II, Smith&Nephew) between May 2010 and October 2012. In all cases, a computed tomography-guided navigation system (Brain LAB, Heimstetten, Germany) was used. All surgery was performed by the subvastus approach and modified gap technique. Intraoperative knee kinematics was measured using the navigation system after implantation and closure of the retinaculum and soft tissue except for the skin. Subjects were divided into two groups based on intraoperative kinematic patterns: a medial pivot group (M group, n=19)(Figure 1) and a non-medial pivot group (N group, n=16)(Figure 2). Subjective outcomes with the new KSS and clinical outcomes were evaluated. Statistical analysis to compare the two groups was made using unpaired a Student t test.

Introduction

The observation of elevated heavy metal ions in arthroplasty patients in association with complications has led to concern on the part of patients and surgeons. The aim of this study was to determine the levels of cobalt chromium ions in three compartments, the joint fluid, plasma, and CSF.

Method

Patients were divided into 3 groups:

239 without any implant(M132F108)

Blood and CSF specimens were harvested at the time of induction of anaesthesia. Joint fluid was aspirated before the surgical incision was made under sterile conditions. Cobalt was assayed using an Agilent7500ce inductively coupled plasma mass spectrometer. Chromium was assayed with a graphite furnace atomic absorption spectrometer (Varian240zlGFAAS). Bivariate correlations were used to determine similarities between group

Introduction

Mechanically-assisted corrosion of the head-neck junction present a dilemma to surgeons at revision THR whenever the femoral component is rigidly fixed to the femur. Many remove the damaged femoral head, clean the femoral taper and fix a new head in place to spare the patient the risks associated with extraction and replacement of the well-functioning femoral stem. This study was performed to answer these research questions:

Will new metal heads restore the mechanical integrity of the original modular junction after impaction on corroded tapers?

Materials and Methods

Twenty-two tapers (CoCr, n=12; TiAlV, n=10) were obtained for use in this study. Ten stems were in pristine condition, while 12 stems had been retrieved at revision THR and with corrosion damage to the trunnion (Goldberg scale 4). Twenty-two new metal heads were obtained for use in the study, each matching the taper and manufacturer of the original component. The following test states were performed using a MTS Machine: 1. Assembly, 2. Disassembly, 3. Assembly, 4. Toggling and 5. Disassembly. All head assemblies were performed wet using 50% calf serum in accordance to ISO 7206-10. During toggling, each specimen's loading axis was aligned 25° to the trunnion axis in the frontal plane and 10° in the sagittal plane (Figure 1). Toggling was performed at 1Hz for 2,000 cycles with a sinusoidal loading function (230N–4300N). During loading, 3D motion of the head-trunnion junction was measured using a custom jig rigidly attached to the head and the neck of each prosthesis. Relative displacement of the head with respect to the neck was continuously monitored using 6 high resolution displacement transducers with an accuracy of ±0.6µm. Displacement data was independently validated using FEA models of selected constructs.

INTRODUCTION

The timely identification of outliers (implants, surgeons or patients) using prospectively collected registry data is confounded by many factors, including the assumption that the sampled population is representative of the entire cohort of patients. In this study we utilized a computer simulation of a joint registry to address the question: How does incomplete enrollment of patients in registries affect the reliability of identification of outliers, and what percent capture of the target population is sufficient?

MATERIALS AND METHODS

A synthetic registry was created consisting of 10,000 patients (100 surgeons), of whom, 1000 underwent joint replacement using a new implant. A predictive model for the risk of revision was created from data published by the Swedish TKR Registry and the AOANJRR. The pairing of patients, surgeons and implants was randomized and for each assignment, the probability of revision was computed. We then chose random samples of all patients in 10% increments from 10% to 100%, simulating incomplete capture of all potential cases by the registry. For each sample we calculated the number of cases of the new implant predicted to end in revision. The assignments were repeated 2000 times using implants with revision rates of 1.5%, 2.0% and 3.0% per annum vs. 1.0% for all other implants of the same class.

Introduction

Manifestation of high interface stresses coupled with micromotion at the interface can render the taper lock joint in a modular hip replacement prosthesis at risk for failure. Bending can lead to crevice formation between the trunnion and the head and can potentially expose the interface to the biological fluids, generating interface corrosion. Additionally, development of high stresses can cause the material to yield, ultimately leading to irreversible damage to the implant. The objective of this study is to elucidate the mechanical response of taper junction in different material combination assemblies, under the maximum loads applied during everyday activities.

Methods

Computer simulations were executed using a verified FE model. A stable hexahedral mesh (33648 elements) was generated for the trunnion (taper size: 12/14mm) and a tetrahedral mesh (51182 elements) for the head (CoCr, size: 32mm). An assembly load of 4000N was applied along the trunnion axis followed by the application of a load of 230–4300N at 25° and 10° angle to the trunnion axis in the frontal and sagittal planes. A linear static solution was set up using Siemens NX Nastran. Two material combinations were tested - cobalt-chrome head with a titanium alloy trunnion and cobalt chrome head with a cobalt-chrome trunnion.

Background

With the rising demand for primary total hip arthroplasty (THA), there has been an emphasis on reducing the revision burden and improving patient outcomes. Although studies have shown that primary THA effectively minimizes pain and restores normal hip function for activities of daily living, many younger patients want to participate in more demanding activities after their operation. The purpose of this study was to examine the relationship between age, gender and patient satisfaction after total hip arthroplasty.

Methods

With IRB approval, 2 groups of subjects were enrolled in this study: (i) 143 patients at an average of 25 months (range 10–69 months) post-primary THA, and (ii) 165 control subjects with no history of hip surgery or hip pathology. All subjects were assigned to one of four categories according to their age and gender: Group A: 40–60 year old males (31 THA; 42 Controls), Group B: 40–60 year old females (25 THA; 53 Controls), Group C: 60–80 year old males (35 THA; 25 Controls), and Group D: 60–80 year old females (36 THA; 23 Controls). Each patient completed a self-administered Hip Function Questionnaire (HFQ) which assessed each subject's satisfaction, expectations, symptoms and ability to perform a series of 94 exercise, recreational and daily living activities. These included participation in work-out activities, adventure and water sports, running and biking, and contact and team sports. Each participant was also asked their activity frequency, symptom prevalence and satisfaction with their hip in performing each activity.

Background

The current orthopaedic literature demonstrates a clear relationship between acetabular component positioning, polyethylene wear and risk of dislocation following Total Hip Arthroplasty (THA). Problems with edge loading, stripe wear and squeaking are also associated with higher acetabular inclination angles, particularly in hard-on-hard bearing implants.

The important parameters of acetabular component positioning are depth, height, version and inclination. Acetabular component depth, height and version can be controlled with intra-operative reference to the transverse acetabular ligament.

Control of acetabular component inclination, particularly in the lateral decubitus position, is more difficult and remains a challenge for the Orthopaedic Surgeon. Lewinnek et al described a ‘safe zone’ of acetabular component orientation: Radiological acetabular inclination of 40 ± 10° and radiological anteversion of 15 ± 10°.

Accurate implantation of the acetabular component within the ‘safe zone’ of radiological inclination is dependent on operative inclination, operative version and pelvic position.

Traditionally during surgery, the acetabular component has been inserted with an operative inclination of 45°. This assumes that patient positioning is correct and does not take into account the impact of operative anteversion or patient malpositioning.

However, precise patient positioning in order to orientate acetabular components using this method cannot always be relied upon. Hill et al demonstrated a mean 6.9° difference between photographically simulated radiological inclination and the post-operative radiological inclination. The most likely explanation was felt to be adduction of the uppermost hemipelvis in the lateral decubitus position. The study changed the practice of the senior author, with target operative inclination now 35° rather than 40° as before, aiming to achieve a post-operative radiological inclination of 42° ± 5°.

Aim

To determine which of the following three techniques of acetabular component implantation most accurately obtains a desired operative inclination of 35 degrees:

Freehand

Introduction

Antibiotic-loaded acrylic cement (ALAC) is employed in the treatment or prevention of infected total hip arthroplasty (THA). We have administered vancomycin (VCM) as the ALAC for the treatment of THAs with methicillin-resistant Staphylococcus aureus, or for the prevention of THAs with high risks. This study aimed to evaluate the serum concentration of VCM from ALAC in THA or cement beads.

Methods

Between December 2013 and February 2014, 16 hips (16 patients) underwent application of the ALAC including VCM at our institution. Two hips were used for the treatment of infection, in the first stage of two-staged revision THAs (i.e., cement beads). Two hips were used for the both treatment and prevention of infection, in one-staged revision THAs. Twelve hips were used for the prevention of infection, in aseptic revision THAs or primary THAs with high risks. Patients were classified into two groups depending on the VCM concentration of ALAC, as follows: high-dose group (2 hips), average 4.4% (3.8–5.0%); low-dose group (14 hips), average 1.6% (1.3–2.5%). The amount of VCM placed as ALAC into the hip was calculated by using the remaining ALAC. The serum concentration of VCM was evaluated at 1 day, 4 days, 7 days, and 28 days after surgery. Statistical analysis was performed by using the t-test, and the differences were considered significant when the p value was <0.05.

Puropose

Three-dimensional (3D) templating based on computed tomography (CT) in total hip arthroplasty improves the accuracy of implant size. However, even when using 3D-CT preoperative planning, getting the concordance rate between planned and actual sizes to reach 100% is not easy. To increase the concordance rate, it is important to analyze the causes of mismatch; however, no such studies have been reported. This study had the following two purposes: to clarify the concordance rate in implant size between 3D-CT preoperative planning and actual size; and to analyze risk factors for mismatch.

Materials and Methods

A single surgeon performed 149 THAs using Trident Cup and Centpillar Stem (Stryker) with CT-based navigation between September 2008 and August 2011. Minimal follow-up was 2 years. Patients with incomplete postoperative CT were excluded from this study. Based on these criteria, the study examined 124 hips in 111 patients (mean age, 60 years, mean BMI 23.2 kg/m2). The preoperative diagnosis was primary osteoarthritis in 8 hips, secondary osteoarthritis in 102 hips, osteonecrosis in 9 hips, rapidly destructive coxopathy in 4 hips and rheumatoid arthritis in 1 hip. We compared cup and stem sizes between preoperative planning and intraoperatively used components. Radiological evaluations were cortical index and canal flare index on preoperative X-rays. We evaluated preoperative planning and postoperative components for cup orientation, cup position, and stem alignment (anteversion, flexion and varus angle) on the CT-navigation system. Fixation of the stem was evaluated by X-ray radiography at 2 years postoperatively according to Engh's criteria. Statistical analysis was performed with the Mann-Whitney U test, and values of P<0.05 were considered statistically significant.

Background

A careful consideration of change of the rotational profiles of total limb after unilateral total knee arthroplasty is necessary. The aim of the present study was to evaluate the discrepancies of rotational profiles of total limb between operated and non-operated limb following unilateral total knee arthroplasty.

Methods

We conducted a retrospective analysis the CT data from 32 patients undergoing primary unilateral total knee arthroplasty using measured resection technique, which femur implant was applied at an external rotation of 3° relative to the posterior condylar axis from July 2009 to April 2013 in our hospital. Using these CT studies, rotational profiles of total limb such as femoral torsion angle (femoral neck anteversion angle; FTA), tibial torsion angle (TTA), neck-malleolar angle (NMA), knee joint rotation angle (rotational mismatch; KJRA) and total limb rotation (TLR) were measured.

Purpose

The purpose of this study was to examine the progression of osteoarthritis (OA) on patella-femoral joint (PFJ) after open wedge high tibial osteotomy (OWHTO) and unicondylar knee arthroplasty (UKA) in correlation with pain and functional outcomes.

Methods

We conducted a retrospective analysis of 101 knees (89 patients), which received an OWHTO in 42 knees and UKA in 59 knees between 2003 and 2008 with minimum 5-years follow-up. Preoperative and the last follow-up radiologic evaluations were performed on the specific radiographic parameters that reflect the patella and knee alignment. Progressions of OA on PFJ at pre-operation and the last follow up were assessed and compared with modified OA grading system. The patella-femoral (PF) pain and function score were recorded using modified PF scoring system at the last follow up.

Introduction

Bulk bone grafting of the cup is commonly used in total hip arthroplasty (THA) for developmental dysplasia. However, it carries a risk of the graft collapse in the mid-term or long-term results. The purpose of this study is to describe our new bulk bone grafting technique and review the radiographic and clinical results.

Patients and Methods

We retrospectively reviewed 85 hips in 74 patients who had undergone bulk bone grafting in total hip arthroplasty for developmental dysplasia between 2008 and 2013. We excluded patients who had any previous surgeries or performed THA with the femoral shortening osteotomy. According to the Crowe classification, 4 hips were classified as Type 1, 28 as Type 2, 35 as Type 3, and 18 as Type 4. Follow-up was at a mean of 4.0 years (1 to 6.1). The surgery was performed using the direct anterior approach on a standard surgical table. The acetabulum was reamed for as close to the original acetabulum as possible. The pressfit cementless cup was impacted into the original acetabulum. After the pressfit fixation of the cup was achieved, two or three screws were used to reinforce the fixation. The superior defect of the acetabulum was packed with sufficient amount of morselized bone graft. Then, the bulk bone was placed on the morselized bone graft and fixed with one screw. Post-operatively, there were no restrictions to movement or position. On the first day after surgery, the patient was allowed to walk with full weight-bearing. We measured the height of the hip center from the interteardrop line and the pelvic height on anteroposterior roentgenograms of the pelvis and calculated the ratio of the hip center to the pelvic height. We defined the anatomical hip center as the height of the center less than 15% of the pelvic height.

Introduction

Radiographs and computed tomography (CT) images are used for the preoperative planning in total knee arthroplasty (TKA), however, these two-dimensional (2D) measurements are affected easily by limb position and scanning direction relative to three-dimensional (3D) bone model analyses. The purpose of our study was to compare these measurements to evaluate the factors affecting the difference.

Patients and Methods

A total of 75 osteoarthritis knees before primary TKA were assessed. The full-length weight-bearing anteroposterior radiograph and CT slices were used for the 2D measurement. Three-dimensional measurement used 3D bone model reconstructed from the CT data and the coordinate system as the previous reports (Figure 1). We measured FVA (femoral valgus angle), CRA (the angle between the posterior condylar line <PC-L> and the clinical epicondylar axis <CEA>), and SRA (the angle between the PC-L and the surgical epicondylar axis <SEA>). Intra- and inter-observer reliabilities were assessed by intraclass correlation coefficients (ICC), and the differences between the 2D and the 3D measurements (Differences) were evaluated. In addition, we evaluated whether preoperative factors (preoperative extension angle, HKA, BMI and CT scanning direction) affected the differences between the 3D and the 2D measurements. Computer simulation was used to examine the influences of CT scanning direction.

Background

Adjusting the joint gap length to be equal in both extension and flexion is an important issue in total knee arthroplasty (TKA). Tight flexion gaps occur sometimes, particularly with the cruciate-retaining (CR) type of TKA, and it impede knee flexion. In posterior stabilizing (PS) TKA, because sacrificing the PCL increases the flexion gap, the issue of gap balancing with PS-TKA is usually focused on decreasing the enlarged flexion gap to be equal to the extension gap. It is generally known that posterior tibial slope would affect the flexion gap, however, the extent to which changes in the tibial slope angle directly affect the flexion gap remains unclear. This study aimed to clarify the influence of tibial slope changes on the flexion gap in CR- or PS-TKA.

Methods

The flexion gap was measured using a tensor device with the femoral trail component in 20 cases each of CR- and PS-TKA. A wedge plate with a 5° inclination was placed on the tibial cut surface by switching its front–back direction to increase or decrease the tibial slope by 5°. The flexion gap in changing the tibial slope was compared to that of the neutral slope measured with a flat plate that had the same thickness of the wedge plate center.

Introduction

MERA Quest Knee System (Quest Knee) is a posterior cruciate ligament–retaining prosthesis considering the anatomical features and lifestyles of the Japanese. As for the anatomical features, we reduced the size of prosthesis and set a smaller interval of sizes because Japanese knees are smaller and flatter than those of Caucasians. As for the lifestyles, we evaluated in vivo patellar tracking during deep knee flexion and the condylar geometry in the axial plane of magnetic resonance imaging. It was found that the patella sank deeply into the intercondylar notch and that the articular surface of the lateral condyle began to curve steeply. We adopted this shape and engraved the lateral condyle deep to reduce the pressure of the patellofemoral joint and to get better range of motion (ROM). For the contact pressure rise in the femorotibial joint by engraving the lateral condyle, the insert was suited to the shape of the femoral component. Furthermore, we increased the thickness of the posterior flange of the femoral component and changed the posterior radius of curvature gradually, and this shape allowed the flexion of 155°. We have used Quest Knee for clinical applications from October 2009. We studied the short-term results of Quest Knee.

Methods

Between June 2010 and July 2013, the same senior surgeon performed 59 consecutive primary operations with Quest Knee. Forty patients (44 knees) were women, and 14 patients (15 knees) were men. The mean patient age was 72.5 years (range, 59–89 years). All were osteoarthritis knees. Coronal deformity was varus in 58 knees and valgus in one knee. All operations were performed with a measured resection technique, and all patellae were resurfaced. Clinical evaluations were assessed using the Japanese Orthopaedic Association knee rating score (JOA score), and clinical ROM and standing femorotibial angle (FTA) were measured. Additionally, three-dimensional motion analysis of the patellar component during squatting was performed by the image matching method with image correlations.

Introduction

Postoperative knee flexion is an important indicator of success in total knee arthroplasty (TKA). Factors influencing the postoperative range of motion (ROM) were reported to be preoperative ROM, primary indication, height of postoperative joint line, patellar thickness, postoperative pain and rehabilitation. In this study, we aimed to identify the relationship between preoperative hip ROMs and postoperative knee flexion through reviewing the TKA results in Japanese patients.

Patients & Methods

We retrospectively reviewed primary TKAs 55 knees in 55 patients (33 left and 22 right) between April 2012 and March 2013 inclusive. The patients were 11 men and 44 women, with a mean age of 76.7 years. Preoperative hip ROMs and perioperative knee flexion were measured by using goniometer. Hip ROMs were flexion, extension, abduction, adduction, external rotation; ER, internal rotation; IR and total rotation; TR (The total rotation added up ER and IR.). Hip ROMs were measured passively, with the pelvis was fixed manually. Postoperative knee flexion was measured in the fourth week. The patients were classified according to the good group (28 knees), the postoperative knee flexion was more than 125 degrees; and the poor group (27 knees), less than 120 degrees. We compared preoperative hip ROMs in each groups. Multiple regression analysis and Single regression analysis were used for comparison between preoperative hip ROMs and postoperative knee flexion. For comparisons between paired groups we used Wilcoxon test, between unpaired groups Mann-Whitney U test. A p value of less than 0.05 was considered significant.

Introduction

The effect of the implant posterior condylar offset has recently generated much enthusiasm among researchers. Some reports were concerned about the relationship between the posterior condylar offset and an extension gap. However, the posterior condylar offset was measured in a flexed knee position or in reference to femoral anatomy alone. Posterior femoral condylar offset relative to the posterior wall of the tibia (posterior offset ratio; POR) is possibly the risk of knee flexion contracture associated with posterior femoral condylar offset after TKA. However, there are no reports concerning the relationship between POR and flexion contracture in vivo. The aim of this study is to evaluate the relationship between the measurement of POR and flexion contracture of the knee in vivo.

Methods

Twenty-seven patients who underwent a primary total knee arthroplasty (PFC Sigma RP-F) were participated in the study. The lateral femoro-tibial angle (lateral FTA) was measured using lateral radiographs obtained by two procedures. Two procedures are applied to obtain true lateral radiographs of the lower extremities. (1) Full-length true lateral radiographs on standing, (2) True lateral radiographs in the prone position (Fig. 1A). ‘Posterior offset ratio’ was defined as Fig. 1B. Significant differences among groups were assessed using two-tailed Student's t-tests. Spearman's correlation analysis was performed to evaluate the relationship between lateral FTA and posterior offset ratio of patients.

Introduction

Femoral neck fracture is a common injury in elderly patients. To restore the activity with an acceptable morbidity and to decrease of mortality, surgical procedures are thought to be superior to conservative treatments. Osteosynthesis with internal fixation for nondisplaced type, and hemiarthroplasty or total hip replacement (hip arthroplasties) for displaced type are commonly performed.

Cemented arthroplasty has been preferred over non-cemented arthroplasty because of less postoperative pain, better mobility and excellent initial fixation of the implant, especially for osteoporotic and stove-pipe bones. However, pressurizing bone cement may cause cardiorespiratory and vascular complications, and occasionally death, which has been termed as “bone cement implantation syndrome”. To avoid the occurrence of this syndrome, non-cemented implants have been developed. However, most implants with the press fit concepts and flat wedge taper designs have a risk of intraoperative and early postoperative periprosthetic fracture.

Recently, we have employed a non-cemented femoral component, which has a lateral expansion to the proximal body as compared to a conventional hip stem. Because of this shape, which is called a “lateral flare”, this stem provides a physiological loading on both the medial and lateral endosteal surfaces of the femur. This is in contrast to conventional hip stem which prioritizes loading on the medial and metaphyseal /dyaphyseal surfaces of the femur. Moreover, the cross section of this stem is trapezoid with the flat posterior surface. This shape provides the stem with rotational stability along the long axis of the femur, and maximizes loading transfer to the posterior aspect of the proximal femur. These mechanical features avoid the need for aggressive impaction of the stem at the time of insertion. It is necessary to only tap gently to achieve the secure initial implant fixation by a “rest fit”. Thus, this technique reduces the risk of fracture.

Patients and methods

We employed this technique using a non-cemented lateral flare design device for displaced femoral neck fractures since 1996. Surgical procedures were performed with posterior approach under the spinal or epidural anesthesia. Full weight bearing ambulation with a walker was allowed on post-op day one.

Introduction

Pulmonary emboli (PE) after total hip and knee arthroplasties is an uncommon event. However, once it happens, it may results in sudden death. Thus, the prophylaxis of venous thromboembolism (VTE), including symptomatic deep vein thrombosis (DVT) and PE, is one of the challenging trials for Orthopaedic surgeons. Many procedures have been developed, e.g. early mobilization, compression stocking, intermittent pneumatic compression (IPC) devices, and anticoagulation agents. However, the most effective treatment for prophylaxis against VTE after the arthroplasties remains undecided.

Recently, many low molecular weight heparin (LMWH) agents are developing, and these are strongly effective for anticoagulation. However, these agents sometimes lead to bleeding complications, and result in uncontrolled critical bleeding. We are introducing our protocol with conventional aspirin as VTE prophylaxis after the arithroplasties.

Patients and methods

All patients prior to the surgeries are evaluated laboratory and duplex venous ultrasonography examinations to exclude thrombophilic or hemophilic conditions, and existence of DVT. Then, the thrombophilic, and also prolonged immobility, obesity, malignant tumors, cardiovascular dysfunction and DVT patients are regarded as high risk for VTE. These are offered a prophylaxis consisting of a removable inferior vena cava (IVC) filter, together with anticoagulant medication. Usually, the filter is removed three months after the surgery. In other patients, the arthroplasties are carried out under the spinal or epidural anesthesia with IPC on both feet. IPC is also applied, except for the periods of ambulation, usually two to three days of hospitalization after surgery. Full weight bearing ambulation with a walker is allowed on post-op day one.

Patients receive aspirin (acetylsalicylic acid) 325 mg daily for six weeks starting the night of surgery. Pain is controlled with celecoxib (COX-2 selective nonsteroidal anti-inflammatory drug) 400 mg daily, and oral narcotics for break through pain. Before discharge, usually within three days post surgery, all patients are evaluated DVT by duplex venous ultrasonography. The incidence of blood loss, wound complications, and subcutaneous ecchymosis are recorded.

Background

High tibial osteotomy is a common procedure to treat symptomatic osteoarthritis of the medial compartment of the knee with varus alignment. This is achieved by overcorrecting the varus alignment to 2–6° of valgus. Various high tibial osteotomy techniques are currently used to this end. Common procedures are medial opening wedge and lateral closing wedge tibial osteotomies. The lateral closing wedge technique is a primary stable correction with a high rate of consolidation, but has the disadvantage of bone loss and change in tibial condylar offset. The medial opening wedge technique does not result in any bone loss but needs to be fixated with a plate and may cause tibial slope and medial collateral ligament tightening.

Purpose

The purpose of this article is to examine correlation between femoral rotational angle and subjective satisfaction of high tibial osteotomy outcome of the range of motion of knee joint.

Background

BHA is popular surgery for femoral neck fractures expecially elderly patients. However, clinical results are variable that factors affecting results are questionable. Therefore we investigated radiologic fators, dysplastic hip whether influences results of BHA.

Methods

Between 2004 and 2009, 200 patients undergoing bipolar hemiarthroplasty for femoral neck fracture were divided two groups; a lateral center edge (LCE) angle of < 16 degree or > 16 degree on anteroposterior radiographs. All surgical procedures were performed by a single surgeon. Dermogrpahic data, the harris hip score, WOMAC index, Koval activity level, and complication were recorded. The minimum follow up interval was 4 years (mean, 7.8 years).

Purpose

The purpose of this study was to evaluate the results of modular revision stems, uncemented fluted, tapered to treat periprosthetic femoral (PFF) fracture; we specifically evaluated fracture union, implant stability, patient outcomes, and complications to compare the differences between cemented and cementless primary stem.

Materials and Methods

We retrospectively reviewed 56 cases of unstable periporsthetic femoral fracture (forty B2 and sixteen B3) treated with the uncemented fluted and tapered modular distal fixation stem with or with or without autogenous bone graft. Clinical outcomes were assessed with Harris Hip Score and WOMAC score. Radiologic evaluations were conducted using Beals and Tower's criteria. Any complication during the follow-up period was recorded.

Introduction

Wear and osteolysis are major contributors which limit the durability of total hip arthroplasty (THA) and ultimately cause it to fail. Efforts were made to decrease the wear by highly cross-linked polyethylene (HXLPE) and using ceramic bearings. The purpose of this study is to analyze the five year performance of large sized (32mm and 36mm) ceramic and metal heads on X3 HXLPE (Stryker, Mahwah, NJ).

Materials and Method

From Jan 2006 to June 2008, 81 consecutive patients with minimum 5 year radiographic and clinical followup were identified from out institutional prospective database. 51 non-cemented THA (45 patients) had ceramic on HXLPE (CoX3) group and 30 hips (29 patients) had metal on HXLPE (MoX3) group. Mean age was 36 ± 8 years (36–76) and 50 ± 9 years (51–86) in ceramic and metal group, respectively. Wear rates were measured on an anteroposterior weight-bearing pelvis radiographs using the computer-assisted Roman software.

Introduction

Micro-arc oxidation (MAO) is an electrochemical method used to treat metal surfaces. It provides nanoporous pits, and thick oxide layers, and incorporates calcium and phosphorus into the coating layer of titanium alloy. This modification on the surface of titanium alloy by MAO coating would improve the ability of cementless stems to osseointegrate. In spite of these structural and chemical advantages, clinical study of total hip arthroplasty (THA) using MAO coated stem has not yet been reported. In this study, we evaluated the clinical and radiographic results associated with cementless grit-blasted tapered-wedge stems that were identical in geometry but differed with regard to surface treatment with or without MAO coating.

Materials & Methods

We performed a retrospective review of 141 THAs using MAO coated stem for a minimum of 5 years and compared them to 219 THAs using the same geometry stem without MAO coating. A cementless Bencox femoral component (Corentec, Seoul, Korea) was used in all hips. It is made of titanium alloy with a straight, double wedged, tapered stem with a rectangular cross-section. Surface treatment was performed using grit blasting with a roughness of 5.5ųm that was available either with or without MAO coating. Clinical and radiographic evaluations were performed preoperatively and at 6 weeks, 3 months, 6 months, and 1 year postoperatively, and then annually.

Background

Recent studies reported that the kinematic alignment of an implant is more physiological than the traditional methods, and therefore results in better clinical outcomes. They found that for kinematic alignment of the implant, the femoral component should be positioned valgus 2 degrees and tibial component in varus 2 degrees without femoral rotation. Other study also claimed that kinematically aligned TKA does not cause any significant failure; rather, it restores the function of the knee. Therefore kinematic alignment was raised for further patient's functional satisfaction.

Purpose

The purpose of our study is to certify correlation between parameters of implant position and postoperative clinical outcomes after kinematic alignment of TKA.

Introduction

Cementless grit-blasted tapered-wedge titanium femoral stems are being used with increasing frequency in hip arthroplasty because of excellent long-term outcomes. However, periprosthetic femur fracture is a potentially worrisome phenomenon in these types of femoral stems. The aim of this study is to report the incidence of stem loosening in association with periprosthetic femur fractures following hip arthroplasty using cementless grit-blasted tapered-wedge stems.

Materials & Methods

A total of 36 Vancouver Type B1 and B2 periprosthetic femur fractures following either hemiarthroplasty or total hip arthroplasty using cementless grit-blasted tapered-wedge titanium femoral stems (GB group) were identified from a retrospective review of the medical records at three participating academic institutions. The control group consisted of 21 Vancouver Type B1 and B2 periprosthetic femur fractures following either hemiarthroplasty or total hip arthroplasty using cementless proximal porous-coated femoral stems (PC group) at the same institutions during the same period of the study. All femoral stems included in this study had been a well-fixed state before the occurrence of periprosthetic femur fractures. All patients in both groups were treated surgically with either open reduction and internal fixation or femoral stem revision. Femoral stem stability was assessed by preoperative radiographs and was confirmed by intraoperative scrutinization. The incidence of stem loosening was compared between the groups.

Background

It is still controversial whether “labral tear” in the pelvis or “pincer type's femoroacetabular impingement syndrome” should be considered a pathologic lesion, and whether they cause the early onset of osteoarthritis in the pelvis.

Hypothesis

The disruption of chondrolabral junction causes degenerative change on hip joint, and the disruption of the vessel tissue to the labrum induces the rapidly progressive degeneration of outside in osteoarthritis changes.

INTRODUCTION

The reported revision rate for THA is below 10% at 10 years. Major factors for revision are aseptic loosening or dislocation of the articulating components. CoC bearings in total hip arthroplasty (THA) have demonstrated very low wear rates. Due to producing the least number of wear particles of any articular bearing used for THA, osteolysis is very rarely observed. Zirconia-platelet toughened alumina (ZPTA) has improved toughness and bending strength while maintaining all other advantageous properties of alumina. Consequently, its clinical fracture rate is minimal and wear resistance is superior to alumina.

OBJECTIVES

Since a trend exists towards the usage of larger bearings the aim of this study was to compare the tribological behavior of different ZPTA/ZPTA THAs with respect to their ball head diameter.

INTRODUCTION

The role and importance of fretting and corrosion in modular hip endoprostheses has become of more and more interest within the last years. Especially bearing couples with large diameters may experience high friction moments leading to an increase of relative micro movements between the surfaces of the taper connections. Recently published studies show that the risk of fretting and corrosion is significantly reduced by using ceramic ball heads compared to metal ball heads.

OBJECTIVES

Goal of this study was to investigate the risk of fretting and corrosion as well as possible loosening of large ceramic ball heads with metal sleeves.

INTRODUCTION

Ceramics are excellently suited for applications in arthroplasty, mainly total hip, knee and shoulder replacement. As the most prominent representative of this demanding type of material, BIOLOX^®delta is widely used and very successful in the market for more than 10 years. The ability of zirconia phase transformation (t-ZrO₂→m-ZrO₂) in zirconia-platelet toughened alumina (ZPTA) ceramics is an indispensable prerequisite for their excellent mechanical properties. The degree of stabilization of the zirconia tetragonal phase at body temperature is essential for the desired toughening mechanism. Y₂O₃ is the most widely used t-ZrO₂ chemical stabilizer; also microstructure and grain size contribute to t-ZrO₂ phase stabilization. Stabilization must be achieved such that no material degradation will occur in body environment, i.e. in aqueous liquid (synovia), which is known to potentially trigger phase transformation at the surface of ceramic components. In this study, it is shown how phase stabilization in BIOLOX^®delta as a reference material is excellently balanced by means of optimal mechanical performance and environmental stability.

OBJECTIVES

To assess the influence of t-ZrO₂ chemical stabilization on ZPTA properties, in terms of fracture toughness (i.e. the ability to resist crack extension), wear resistance and environmental stability.

Introduction

The number of total hip replacements (THR) increased around 3.5% by year in last decade. Osteoarthritis is the most important disease in the hip, with a prevalence of 10% in the older population (>85 years), according to the Swedish THA Register. THR have been increasing in last years, mainly in young patients between 45 to 59 years old. This type of patients needs a long term solution to prevent hip revision. Two commercial solutions for young patients, the resurfacing prosthesis and press fit one, were analysed in the present study by experimental and numerical models.

Methods

Two synthetic left models of composite femur (Sawbones^®, model 3403), which replicates the cadaveric femur, and two composite pelvic bones were used to introduce two Comercial models of Hip resurfacing (Birmingham model) and Press-fit stem (Laffit Selft –locking stem press-fit model). The commercial hip stems were chosen according to the femurs head size (resurfacing) and the femur size to press-fit Hip stem. Then, they were introduced by an experimented surgeon. The experimental set-up was applied according to a system defined previously by Ramos et al. (2013). Numerical models were implemented by replicating the experimental tests. A 3D scanning was used to identify the stem position in each model. The properties of cortical and cancel bone and hip prosthesis were also taken into account by these models. Contact was established in the interfaces for both press-fit solutions. The femur rotates distally and Pelvic moves up and down according model changes, in order to guarantee models with the same boundary conditions.

Introduction

Hip resurfacing arthoplasty (HRA) is an alternative to total hip arthroplasty (THA), which has increased in the last years, especially in young patients. A suitable positioning of the resurfacing head is important, mainly because it is strongly related with the neck fracture. The goal of this work was to evaluate the influence of the resurfacing head positioning in the load distribution along the femurs’ structures.

Materials and methods

Using 3D scan technology, the exterior geometry of a composite femur, used to create the FE models, was obtained. Three resurfacing models were used in three different positions in the frontal plane. A model with a positive offset of +5mm (Resurfacing #1), in neutral position (Resurfacing #2), and with a negative offset of −5mm (Resurfacing #3) was developed. A Birmingham® Hip Resurfacing prosthesis was chosen according to the femurs’ head. It was positioned in the femur and acetabulum by an experimented surgeon. The metal on metal contact pair was implemented. Models were aligned with 7° and 9°, considering the position of the anatomical femurs in sagittal and frontal planes. Models were constrained on the wing of the ilium and ischial tuberosity, allowing only vertical and rotational movements on the iliac side. Femurs were constrained on its distal side, allowing only rotational movements.

Introduction

Anterior knee pain (AKP) is a recognized cause of patient's dissatisfaction after total knee arthroplasty. Potential implant/technique related contributors to AKP are patellofemoral maltracking, trochlear geometry, femoral malrotation, patellar tilt and overstuffing. The primary aim of this prospective, matched pair study was to assess the safety, efficacy and performance of an anatomic patella and its effect on AKP in in a matched pair analysis.

Material and Methods

Between July 2012 and May 2013, 55 consecutive posterior stabilized cemented Attune TKAs (Depuy) were matched to the PFC Sigma group based on age, gender, and body mass index (BMI). All surgeries were performed via medial parapatellar approach with patellar resurfacing. Clinical and radiographic analysis was performed prospectively with minimum 6 month follow-up. Radiographic measurements included overall limb alignment, anterior offset, posterior offset, joint line, patellar thickness, patellar tilt and patellar displacement by two independent observers.

Introduction

Total hip arthroplasty (THR) with non-cemented or hybrid fixation remains one of the most successful procedures performed today. The aim of this study was to assess the safety and efficacy of a hydroxyapatite (HA) coated, hemispherical cup.

Material and Methods

Between 2003 and 2007, 223 THAs (210 patients) with peripheral self-locking (PSL) cup and highly cross-linked polyethylene (Crossfire, Stryker, Mahwah, NJ) with minimum 5 years clinical and radiographic follow-up (5–9 years) were analyzed. The mean age was 62.5 years ± 10.8 (range, 32.7 – 86.3) at the time of surgery and the predominant preoperative diagnoses was osteoarthritis (97.8%). 72% were solid cups without screw augmentation and 28% were multi-hole with screw. Clinical analysis included Hospital for Special Surgery (HSS) hip scores at latest follow-up. Detail radiographic analysis was carried out on anteroposterior and false profile views for evidence of osseointegration in all Charnley's zones. Osseointegration was assessed based on presence of Stress Induced Reactive Cancellous Bone (SIRCaB) with trabecular bone hypertrophy 5–15mm extending from the cup, and absence of radiolucency or demarcation. EBRA software was used to assess cup positioning.

Introduction

Potential implant and technique related factors to improve patellofemoral (PF) kinematics in total knee arthroplasty (TKA) are design of trochlear geometry and patella, restoration of posterior offset, patellar tilt and avoid overstuffing. The primary aim of this prospective, matched pair study was to assess the radiographic features of PF kinematics with an anatomic patella.

Material and Methods

Between July 2012 and May 2013, 49 consecutive posterior stabilized cemented Attune TKAs (Depuy Synthes Warsaw Indiana) were matched to the 49 PFC Sigma (Depuy) based on age, gender, and body mass index (BMI). All surgeries were performed via medial parapatellar approach with patellar resurfacing. Radiographic analysis was performed prospectively with minimum 1-year follow-up and included overall limb alignment, anterior offset, posterior offset, joint line, patellar thickness, patellar tilt and patellar displacement by two independent observers.

Background

Highly cross-linked polyethylene (HCLPE) was introduced to reduce wear and osteolysis in total hip arthroplasty (THA). There is no reported data regarding wear rates and clinical performance of Crossfire HCLPE (Stryker, Mahwah, New Jersey) in young and active patients. The purpose of this prospective study is to assess minimum 10-year wear rates and survivorship of Crossfire in young and active patients.

Material and Methods

Between January 2001 to December 2003, 52 consecutive THAs (43 patients; 26 males and 17 females), 55 years and younger, with an average University of California Los Angeles activity (UCLA) score of 7.3 ± 1.5 (5 – 10) at the time of surgery were prospectively followed. The mean age of patients was 47.4 ± 7.8 years old (range 24 to 55 years). Indication for surgery included osteoarthritis in all cases. All operations were performed by the senior surgeon via a posterolateral approach. All components were non-cemented SecurFit femoral stem, 28 mm Cobalt-Chromium (Co-Cr) femoral head, and Trident PSL cup with Crossfire HCLPE acetabular liner (Stryker, Mahwah, New Jersey). At minimum 10-years follow-up (mean 11.5 ± 0.94 years), wear rates were assessed using the Roman software. Hospital for Special Surgery (HSS) scores and survivorship data were analyzed.

Introduction

Periprosthetic bone remodelling after Total Knee Arthroplasty (TKA) may be attributed to local changes in the mechanical strain field of the bone as a result of the stiffness mismatch between high modulus metallic implant materials and the supporting bone. This can lead to significant loss of periprosthetic bone density, which may promote implant loosening, and complicate revision surgery. A novel polyetheretherketone (PEEK) implant with a modulus similar to bone has the potential to reduce stress shielding whilst eliminating metal ion release. Numerical modelling can estimate the remodelling stimulus but rigorous validation is required for use as a predictive tool. In this study, a finite element (FE) model investigating the local biomechanical changes with different TKA materials was verified experimentally using Digital Image Correlation (DIC). DIC is increasingly used in biomechanics for strain measurement on complex, heterogeneous anisotropic material structures.

Methodology

DIC was used following a previously validated technique [1] to compare bone surface strain distribution after implantation with a novel PEEK implant, to that induced by a contemporary metallic implant. Two distal Sawbone® femora models were implanted with a cemented cobalt-chromium (CoCr) and PEEK-OPTIMA® femoral component of the same size and geometry. A third, unimplanted, intact model was used as a reference. All models were subjected to standing loads on the corresponding UHMWPE tibial component, and resultant strain data was acquired in six repeated tests. An FE model of each case, using a CT-derived bone model, was solved using ANSYS software.

INTRODUCTION

Use of a novel ligament gap balancing instrumentation system in total knee arthroplasty (TKA) resulted in femoral component external rotation values which were higher on average, compared to measured bone resection systems. In one hundred twenty knees in 110 patients the external rotation averaged 6.9 degrees (± 2.8) and ranged from 0.6 to 12.8 degrees. The external rotation values in this study were 4° and 2° larger, respectively, than the typical 3° and 5° discrete values that are common to measured resection systems. The purpose of the present study was to determine the effect of these greater external rotation values for the femoral component on patellar tracking, flexion stability and function of two different TKA implant designs.

METHODS

In the first arm of the study, 120 knees in 110 patients were consecutively enrolled by a single surgeon using the same implant design (single radius femur with a medial constraint tibial liner) across subjects. All patients underwent arthroplasty with tibial resection first and that set external rotation of the femoral component based upon use of a ligament gap balancing system. Following ligament tensioning / balancing, the femur was prepared. The accuracy of the ligament balancing system was assessed by reapplying equal tension to the ligaments using a tensioning bolt and torque wrench in flexion and extension after the bone resections had been made. The resulting flexion and extension gaps were then measured to determine rectangular shape and equality of the gaps. Postoperative Merchant views were obtained on all of the patients and patellar tracking was assessed and compared to 120 consecutive total knee arthroplasties previously performed by the same surgeon with the same implant using a measured resection system. In the second arm of the study, 100 unilateral knees in 100 patients were consecutively enrolled. The same instrumentation and technique by the same surgeon was used, but with a different implant design (single radius femur without a medial constraint tibial liner).

Introduction

Originally, the vertical expandable titanium rib (VEPTR™) was developed to treat children with Thoracic insufficiency syndrome secondary to fused ribs and congenital scoliosis. Over the years its usage has widen and is currently being used to treat all etiology of early onset scoliosis (EOS). A major draw back remains the size of the titanium VEPTR™ implant. In keeping with the new trend of chrome-cobalt alloy (CoCr). spinal implants, we set out to explore if redesigning the VEPTR™ was mechanically sound. The aim of this study was twofold. Firstly, we investigate the mechanical properties of a VEPTR™ made with CoCr alloy compared to that of titanium alloy. Secondly we investigated how much we could down size the VEPTR™.

Materials & Methods

Finite element analyses were performed on 3 different VEPTR™ designs (rod diameter of 6mm, 5mm and 4mm) subjected to a compressive load of 500N (equivalent to a 50Kg child). For each configuration, two materials, titanium alloy and chrome-cobalt alloy, were used. Maximum Von Mises stress distribution (VMSD), plastic strain (PS) and total displacement (TD) of the VEPTR™ were measured as indicators of mechanical properties of the implant.

Introduction

Typical failure of cementless total hip arthroplasty is the lack of initial stability. Indeed, presence of motion at the bone implant-interface leads to formation of fibrous tissue that prevents bone ingrowth, which in turn may lead to loosening of the implant. It has been shown that interfacial micromotion around 40 produces partial ingrowth, while micromotion exceeding 150 completely inhibits bone ingrowth. Finite element analyses (FEA) are widely used to evaluate the initial stability of cementless THA in pre-clinical validation. Untill now, most FE models developed to predict initial stability of cementless implants were performed based on static load, by selecting the greatest load at a particular time of the cycle activity, but in fact the hip is exposed to varied load during the activity. The aim of this study is to investigate the difference in the predicted micromotion induced by static, quasi-static and dynamic loading conditions.

Materials & Methods

Finite element analysis (FEA) was performed on a Profemur®TL implanted into a composite bone. The implant orientation was validated in a previous study [3]. All materials were defined as linear isotropic homogeneous. Static and dynamic FEA was performed for the loading conditions defined by simulating stair-climbing. In the static analysis, the applied resultant force (calculated with a body weight of 836N) were 951N and 2107N to simulate the abductor muscle and the hip joint contact forces, respectively [4]. In the dynamic analysis, the applied resultant force can be seen on Fig. 1. The initial stability was extracted on 54 points (Fig. 2) located on the plasma spray surface by calculating the difference between the final displacement of the prosthesis and the final displacement of the composite bone.

Introduction

After arthroplasty, stress shielding and high shear stresses at the bone-implant interface are common problems of load bearing implants (e.g. hip prostheses). Stiff implants cause stress shielding, which is thought to contribute to bone resorption¹. High shear stresses, originated by low-stiffness implants, have been related to pain and interfacial micro-movements², prohibiting adequate implant initial fixation.

A non-homogeneous distribution of mechanical properties within the implant could reduce the stress shielding and interfacial shear stresses³. Such an implant is called “functionally graded implant” (FGI). FGI require porous materials with well-controlled micro-architecture, which can now be obtained with new additive manufacturing technologies (e.g. Electron Beam Melting).

Finite element (FE) simulations in ANSYS-v14.5 are used to develop an optimization methodology to design a hip FGI.

Methodology

A coronal cut was performed on a femur model (Sawbones®) with an implanted Profemur®TL (Wright Medical Inc.) stem to obtain the 2D-geometry for FE simulations.

The central part of the FGI stem was made porous, the neck and inferior tip were solid. Ti6Al4V elastic material was assumed (E=120 GPa, v=0.3). Three bone qualities were considered for the optimization: poor (E=6GPa; v=0.3); good (E=12GPa; v=0.3); excellent (E=30GPa; v=0.3).

The structure of bone evolves to maintain a reasonable level of the strains. Similarly in the proposed algorithm, the strut sections of the porous material evolve to keep stresses (proportional to strains) at a reasonable level. Starting with a very small strut section, resulting in an almost zero-rigidity stem, strut sections are increased or decreased as a function of the stresses they support. This is done incrementally, until force values corresponding to normal walking of an 80 kg person (1867 N)⁴ are reached. Force direction was vertical and no action of the abductors was considered, to analyze the worst case scenario. The optimized FGI microstructure is defined by the strut diameter distributions. Since the distance between struts remain constant, variations in strut diameters result in variations in density.

Optimized FGI porous structure was compared for the three bone qualities considered and with a solid stem in terms of bone stresses.

Background

Obtaining accurate alignment in total knee arthroplasty (TKA) remains a concern. Patient specific instrumentation (PSI) created using preoperative 3D modelling was developed to offer surgeons a simplified, reliable, efficient and customised TKA procedure.

Methods

In this prospective study, 60 patients who underwent TKA with conventional instrumentation and 71 patients operated on using PSI were followed for 1 year.(Table 1) The primary endpoint was surgical time. Secondary endpoints included the number of instrument trays used, radiographic limb alignment and clinical outcomes.

Introduction

Recently ventral plating implants made of carbon/PEEK composite material have been developed with apparently superior material properties in terms of implant fatigue and imaging suitability. In this study we assessed the outcome of the first clinical application of this new implant.

Methods

Retrospective, single-center case series of 16 consecutive patients between 2011 and 2013 undergoing ventral stabilization surgery with a new carbon plating system (see figure 1).

We collected data in terms of safety of the procedure (screw positioning, blood loss, operation time), quality and reliability of the implant (revisions, dislocations, screw loosening, fusion, adjacent segment degeneration), clinical outcome and biological tolerance (cervical pain / discomfort, dysphagia).

Introduction

Conventional implant designs in total knee arthroplasty (TKA) are based on metal on UHMWPE bearing couples. Although this procedure is quite successful, early loosening is still a matter of concern. One of the causes for early failure is stress shielding, leading to loss of bone stock, periprosthetic bone fractures and eventually aseptic loosening of the component. The introduction of a polyetheretherketone (PEEK) on UHMWPE bearing couple could address this problem. With mechanical properties more similar to distal (cortical) bone it could allow stresses to be distributed more naturally in the distal femur. A potential adverse effect, however, is that the femoral component and the underlying cement mantle may be at risk of fracturing. Therefore, we analyzed the effect of a PEEK-Optima® femoral component on stress shielding and the integrity of the component and cement mantle, compared to a conventional Cobalt-Chromium (CoCr) alloy implant.

Methods

We created a Finite Element (FE) model of a reconstructed knee in gait, based on the ISO-14243-1 standard. The model consisted of an existing cemented cruciate retaining TKA design implanted on a distal femur, and a tibial load applicator, which together with the bone cement layer and the tibial implant is referred to as the tibial construct. The knee flexion angle was controlled by the femoral construct, consisting of the femoral implant, the bone cement and the distal femur. The tibial construct was loaded with an axial force, anterior-posterior (AP) force and a rotational torque, representing the ground reaction force, soft tissue constraints and internal/external rotation of the tibia, respectively. The integrity of the femoral component and cement mantle were expressed as a percentage of their yield stress. Stress shielding in the periprosthetic femur was evaluated by the strain energy (density) in the bone and compared to a model replicating an intact knee joint.

Objective

Mobile bearing unicompartmental knee arthroplasty (UKA) is an effective and safe treatment for osteoarthritis of the medial compartment. However, mobile-bearing UKA needs accurate ligament balancing of flexion and extension gaps to prevent dislocation of the mobile meniscal bearing. Instability can lead to dislocation of the insert. The phase 3 instruments of the Oxford UKA use a balancing technique for the flexion gap (90° of flexion) and extension gap (20° of flexion), thereby focusing attention on satisfactory soft tissue balancing. With this technique, spacers are used to balance the flexion and extension gap. However, gap kinematics in another flexion angle of mobile-bearing UKA is unclear. We developed UKA tensor for mobile-bearing UKA and we assessed the accurate gap kinematics of UKA.

Materials and Methods

Between 2012 and 2013, The Phase 3 Oxford Partial Knee UKA (Biomet Inc., Warsaw, IN) were carried out in 48 patients (71 knees) for unicompartmental knee osteoarthritis or spontaneous osteonecrosis of the medial compartment. The mean age of patients at surgery was 71.6 years and the mean follow-up period was 1.7 years. The mean preoperative coronal plane alignment was 7.4° in varus. The indications for UKA included disabling knee pain with medial compartment disease; intact ACL and collateral ligaments; preoperative contracture of less than 15°; and preoperative deformity of <15°. Each surgery was performed by using different spacer block with 1-mm increments and the meniscal bearing lift-off tests according to surgical technique. We developed newly tensor for mobile bearing UKA which designed to permit surgeons to measure multiple range of the joint medial compartment/joint component gap, while applying a constant joint distraction force (Figure 1). We assessed the intra-operative joint gap measurements at 0, 20, 60, 90 and 120 of flexion with 100N, 125N and 150N of joint distraction forces.

Introduction

Recent literature has shown that RSAs successfully improve pain and functionality, however variability in range of motion and high complication rates persist. Biomechanical studies suggest that tensioning of the deltoid, resulting from deltoid lengthening, improves range of motion by increasing the moment arm. This study aims to provide clinical significance for deltoid tensioning by comparing postoperative range of motion measurements with deltoid length for 93 patients.

Methods

Deltoid length measurements were performed radiographically for 93 patients. Measurements were performed on both preoperative and postoperative x-rays in order to assess deltoid lengthening. The deltoid length was measured as the distance from the infeolateral tip of the acromion to the deltoid tuberosity on the humerus for both pre- and post- x-rays. For preoperative center of rotation measurements, the distance extended from the center of humeral head (estimated as radius of best fit circle) to deltoid length line. For postoperative measurements, the distance was from the center of glenosphere implant to deltoid length line. Forward flexion and external rotation was measured for all patients.

Background and Purpose

Although the treatment for infected total hip arthroplasty (THA) has been still controversial, some reports suggested two-stage revision THA seems to be more preferable rather than one-stage revision. The purpose of this study is to estimate the outcome of treatment for infected THA in our institutions.

Patients and methods

The medical records of patients who have been underwent surgical treatment for infected THA between 2006 and 2012 in two hospitals and followed more than one year after surgery were reviewed. 34 patients and 35 hips were included. Age at surgery, gender, a period until surgical treatment after diagnosis of infection, method of treatment (debridement, one-stage or two-stage revision THA) and the outcome are estimated for each hips. Remission was defined by the absence of local and systemic sign of implant related infection and the normalization of WBC and C-reactive protein value without antibiotics.

Background

In measured resection (MR) technique it is sometimes not easy to equalize extension gap (EG) and flexion gap (FG) because the size of femoral component is generally determined only depending on the anteroposterior and mediolateral size of femoral condyle in MR technique. In order to equalize the EG and FG, femoral implant size should be determined so that the FG is similar to the EG. We developed the novel sizing technique of femoral component to equalize the EG and FG in MR technique. The purpose of this study was to examine the usefulness of this technique.

Methods

Before surgery, the condylar twist angle: CTA (angle between the transepicondylar axis and the posterior condylar axis) was determined for individual knees by transepicondylar view (X ray) or CT. During surgery, after osteophyte was removed EG was made and measured. Knee was flexed in 90° and the specially made tensor which upper paddle has the medial inclination angle (same as the CTA) was inserted to FG before posterior femoral osteotomy. Then, the appropriate traction force was applied to FG. Under this condition, the correct rotational alignment of femur relative to tibia was obtained, and then, the size of femoral component could be determined so that the FG was similar to the EG by measuring the distance between tibial cut surface and posterior cut level of the respective size of femoral conponent. 23 knees that undergone TKA for end stage medial osteoarthritis were examined and the final EG and FG were measured. EG and FG were measured at the mediolateral center of the gap without any trial component.

Purpose

Clinical outocome of revision total elbow arthroplasty(TEA) in rheumatoid arthritis(RA) patients were evaluated.

Methods

Clinical outocome of revision TEA that underwent between 2005 and 2013 were evaluated. Causes of revision, implanted revised prosthesis, a clinical score (the Japanese Orthopaedic Association (JOA) elbow assessment score), the arc of motion and complications were investigated. Totally, 6 patients underwent revision TEA. The patients were females with a mean age of 60.4 years (range, 32 to 72).

Introduction

We have previously reported that patients who demonstrated medial pivot kinematics pattern after total knee arthroplasty (TKA) had better clinical results than that of non-medial pivot pattern. However, it is unclear how preoperative kinematics pattern affects postoperative knee kinematics. The aim of this study was to evaluate the relationship between preoperative and postoperative knee kinematics pattern in TKA.

Materials and Methods

The present study consists of 38 patients with medial osteoarthritis who underwent a primary TKA using a CT-based navigation system from July 2010 to September 2012. All the operations were performed by a single surgeon using a subvastus approach and the same posterior cruciate ligament substituting type (PS type) of prosthesis (Genesis II™ total knee system, Smith & Nephew, Memphis, TN). The proximal tibia osteotomy and the distal femur osteotomy were set on the navigation system perpendicular to the mechanical axis in the coronal plane with 3° tibial posterior inclination in the sagittal plane. The coronal plane ligament imbalance was corrected until the gap imbalance was fewer than 2 mm. This gap balance was checked using a ligament balancer (Smith & Nephew) at 80 N in medial and lateral compartment of the knee. The navigation system was used to measure the flexion gap with the CAS ligament balancer (Depuy, Warsaw, IN, USA) at 90° knee flexion. The amount of external rotation on femoral osteotomy was adjusted by the navigation system with a balanced gap technique. The patella was resurfaced and a lateral release was not performed. Tibial A-P axis of the tibial tray was placed parallel to Akagi's line. We measured each kinematics pattern immediately after capsule incision (preoperative knee kinematics) and after implantation (postoperative knee kinematics) in TKA. Subjects were divided into two groups based on kinematics patterns: a medial pivot group (group M) and a non-medial pivot group (group N). A chi-square test was used for statistical analysis. P values less than 0.05 were considered significant.

Purpose

A Trabecular Metal Modular Acetabular System (Zimmer, Warsaw, Indiana, USA) is a peripheral rim expansion (elliptical) cup, i.e. a non-hemispherical cup. Radiologically a non-hemispherical cup may be deferent from other conventional hemispherical cups. We reviewed radiological findings of a Trabecular Metal Modular Acetabular System chronologically.

Methods

Twenty six patients with osteoarthritis underwent primary total hip arthroplasty (THA) using a Trabecular Metal Modular Acetabular System from 2011 to April 2013. Twenty five patients (follow-up rate: 96.2%) 31 hips could be followed-up over a year were registered. In common, the diameter of every femoral head was 32 mm. We planned the acetabular cup inclination angle to be 45-degree, the cup coverage with host-bone (cup-CE angle) to be over 10-degree, and high hip center was allowed up to 20mm. In case of the cup-CE angle under 10-degree, an acetabular cup was placed medially using Dorr's medial protrusio technique. We established the medial protrusion angle indicating the degree of medial protrusion of an acetabular cup over the pelvic internal wall. The medial protrusion angle was defined by the center point of THA (C) and the 2 cross-points (X₁, X₂) which the outline of an acetabular cup crosses the Kohler's line (Figure 1). The cup anteversion angle was measured by the method of Lewinnek, and the cup fixation was evaluated according to the Tompkin's classification.

Background

Navigation systems that increase alignment accuracies of the lower limbs have been applied widely in total knee arthroplasty and are currently being adopted for minimally invasive UKA (MIS UKA) with good alignment results. There is little debate that when compared with total knee arthroplasty (TKA), UKA is less invasive, causes less morbidity, better reproduces kinematics, and therefore offers quicker recovery, better range of movement and more physiologic function.

However, despite improved alignment accuracies, advantages of use of navigation system in UKA in clinical outcomes and survivals are still debatable. To the best of our knowledge, no reports are available on the long-term results after UKA performing using a navigation system. The purpose of this prospective study was to compare the radiological, clinical, and survival outcomes of UKA that performed using the navigation system and using the conventional technique at average 8 years follows up.

Methods

Between January 2003 and December 2005, Total of 98 UKAs were enrolled for this study, 56 UKAs in the navigation group and 42 UKAs in conventional group were included in this study after a average 8 years follow-up. At the final follow up, the radiological measurements with regard to the mechanical axis, the inclination of the femoral and tibial components, and radiolucent line or loosening were evaluated and compared between two groups. The clinical evaluations were performed using range of motion, Western Ontario and McMaster Arthritis index (WOMAC) scores and Knee Society (KS) score.

Background

Despite the excellent clinical success of total knee arthroplasty (TAK), controversy remains concerning whether or not to resurface the patella. This has led to a number of randomized controlled trials. Randomized controlled trials constitute the most reliable source of evidence for the evaluation of the efficacy of a potential intervention. But most of these studies include all degree of osteoarthritis of the patellofemoral joint. So we did this prospective study to compare clinical and radiological outcomes after TKA with or without patellar resurfacing in patients with grade IV osteoarthritis on patellofemoral joint.

Materials and Methods

123 cases (93 patients) with Kellgren-Lawrence grade IV osteoarthritis on patellofemoral joint were enrolled for this study. At the operating room, they were randomly assigned to undergo patella resurfacing (62 cases) or patella retention (61 cases). Among them, 114 cases that could be followed for more than 2 years were included in this study (resurfacing group; 59 cases, retention group; 55 cases). When patellar retention was performed, osteophytes of the patella were removed and marginal electrocauterization was carried out. Preoperative and postoperative clinical outcomes were evaluated and compared regarding the Hospital for Special Surgery Patellar (HSSP) score (total 100 point; anterior knee pain, functional limitation, tenderness, crepitus, Q-strength). We also compared Hospital for Special Surgery (HSS) and WOMAC scores, and range of motion (ROM). We also compared radiological outcomes at the final follow up, with regards to mechanical axis of the lower limb, patella tilt and patella congruence angle between two groups.