Introduction

The purpose of this study was to examine whether three types of mobile-bearing PCL sacrificing TKA could restore the native knee translation and rotation. The primary hypothesis was that there are differences in knee kinematics and laxity between three different cruciate-substituting TKA designs: 1 with post-cam mechanism, 2 post-cam mechanism based on an inter-condylar ‘third condyle’ concept, 3 anterior stabilized with deep-dished highly congruent tibial insert; specifically, showing different femoral external rotation with flexion, different femoral translation with flexion and different laxity under stress test. The secondary hypothesis was that there is different clinical outcome between the three TKA designs at 2 years follow-up.

INTRODUCTION. Determining proper joint tension in reverse total shoulder arthroplasty (rTSA) can be a challenging task for shoulder surgeons. Often, this is a subjective metric learned by feel during fellowship training with no real quantitative measures of what proper tension encompasses. Tension too high can potentially lead to scapular stress fractures and limitation of range of motion (ROM), whereas tension too low may lead to instability. New technologies that detect joint load intraoperatively create the opportunity to observe rTSA joint reaction forces in a clinical setting for the first time. The purpose of this study was to observe the differences in rTSA loads in cases that utilized two different humeral liner sizes. METHODS. Ten different surgeons performed a total of 37 rTSA cases with the same implant system. During the procedure, each surgeon reconstructed the rTSA implants to his or her own preferred tension. A wireless load sensing humeral liner trial (VERASENSE for Equinoxe, OrthoSensor, Dania Beach, FL) was used in lieu of a traditional plastic humeral liner trial to provide real-time load data to the operating surgeon during the procedure. Two humeral liner trial sizes were offered in 38mm and 42mm curvatures and were selected each case based on surgeon preference. To ensure consistent measurements between surgeons, a standardized ROM assessment consisting of four dynamic maneuvers (maximum internal to external rotation at 0°, 45°, and 90° of abduction, and a maximum flexion/extension maneuver) and three static maneuvers (arm overhead, across the body, and behind the back) was completed in each case. Deidentified load data in lbf was collected and sorted based on which size liner was selected. Differences in means for minimum and maximum load values for the four dynamic maneuvers and differences in means for the three static maneuvers were calculated using 2-tailed unpaired t-tests. RESULTS. No significant differences were observed for the flexion/extension maneuver between the 38mm and 42mm liner sizes, but a significant difference was observed for every internal/external rotation assessment at 0°, 45°, and 90° of abduction. No significant differences were observed for the across the body and overhead maneuvers, but a significant difference was observed for the behind the back maneuver (p = 0.015). Standard deviations were pronounced across all maneuvers. CONCLUSION. This study observed significant differences in intraoperative load values in rTSA when comparing different humeral liner sizes. Limitations of this study include the small sample sizes and large standard deviations observed, as well as comparing across multiple patients and multiple surgeons. Area for future work includes comparing load values with postoperative functional results and complication risks for short, midterm, and long-term outcomes in efforts to find the optimal load range for a given patient

A huge commitment is required from patients and families who undergo a limb reconstruction procedure using the hexapod frame. This includes turning the struts on the frame, pin site care and intensive rehabilitation. Montpetit et al (2009) discovered that function, participation, engagement in regular activities of daily living is severely impacted during the hexapod lengthening period. Due to the long duration and burden for families, it is imperative that healthcare professionals understand the impact that the hexapod frame has on functional abilities and health related quality of life (HRQL).

This project involved a retrospective review of prospectively collected data on function and HRQL during two periods of time: (1) when the hexapod frame is applied on the child's lower extremity and (2) when the lengthening phase is completed, and the hexapod frame is removed. Data from 38 children (mean age: 12 years SD 3.8) who completed lower extremity reconstruction using the hexapod frame and completed either or both the Pediatric Quality of Life Inventory 4.0 Generic Core Scale (PedsQL) and Pediatric Outcomes data Collection Instrument (PODCI) was included. Analysis included, standardized response means, the non-parametric Wilcoxon test and effect size calculation.

A Wilcoxon signed rank test for those children who completed pre and post frame PODCI’;s revealed those scores were significantly greater once the hexapod frame was removed (Md=85.10, n=10) compared to during (Md=66.50, n=10) with a large effect size, r= 1.45. Similar, the PedsQL scores improved post frame removal (Md= 66.30, n=10) compared to during treatment (Md = 53.34, n=10), with a medium size effect, r= 0.62. All subtests improved once the frame was removed.

This study provides essential insights into the burden of the hexapod frame for children and provides valuable information for all allied healthcare professionals targeted interventions for health domains. This study shows that children's function improves once the hexapod frame is removed. However, this study highlights the importance for all healthcare professional to address health domains for the duration of the hexapod procedure where the child scored lower e.g. sports and physical function, pain and comfort, happiness from the PODCI. The PedsQL identified lower mean scores in physical and emotional function.

The New Zealand Joint Registry (NZJR) was established in 1999. However, ethnicity data was not recorded by prioritisation in line with Ministry of Health (MoH) recommendations. Recently, cross-referencing with MoH updated ethnicity data for all 326,150 entries in the NZJR database. The objective of this national level, population study was to identify any ethnic disparities in access and outcome for Māori for primary total hip (THA) and knee arthroplasty (TKA) for Osteoarthritis.

The utilisation rate for THA and TKAs were calculated for the Māori and NZ European population from all data in the NZJR and Census data in 2001, 2006, 2013 and 2018. Utilisation rate was reported separately for four age groups (<55, 55-64, 65-74, >75) over four time periods (1999-2004, 2005-2009, 2010-2014, 2015-2020). Revision rate, 6 months and 5-year Oxford scores were adjusted for age, sex and BMI, then compared between groups.

In every age group and at all but one time point, significant under-utilisation of TKA was observed in Māori. For THAs, Māori had similar utilisation rates in the <55 and 55-64 age groups, but significantly lower utilisation rates in all other age groups.

When adjusted for age, sex and BMI, no significant differences in revision rates were observed between Māori and NZ Europeans for THAs (HR 0.939, P 0.417) or TKAs (HR 1.129, P 0.149). Adjusted 6 months and 5-year Oxford scores were significantly higher in NZ Europeans, however, the maximum difference was less than 3 points and is unlikely to be clinically significant.

Despite the same risk of being diagnosed with osteoarthritis, Māori are less likely to undergo THA and TKA. There are no clinically significant differences in outcomes post arthroplasty between Māori and NZ Europeans. Further research is required to investigate causes for lower utilisation in Māori.

Introduction

LIMB-Q Kids is a new patient-reported outcome measure (PROM) for children with Lower limb differences (LLDs). The objective is to conduct an international field test study.

Functional outcomes are commonly reported in studies of musculoskeletal oncology patients undergoing limb salvage surgery; however, interpretation requires knowledge of the smallest amount of improvement that is important to patients – the minimally important difference (MID). We established the MIDs for the Musculoskeletal Tumor Society Rating Scale (MSTS) and Toronto Extremity Salvage Score (TESS) in patients with bone tumors undergoing lower limb salvage surgery.

This study was a secondary analysis of the recently completed PARITY (Prophylactic Antibiotic Regimens in Tumor Surgery) study. This data was used to calculate: (1) the anchor-based MIDs using an overall function scale and a receiver operating curve analysis, and (2) the distribution-based MIDs based on one-half of the standard deviation of the change scores from baseline to 12-month follow-up, for both the MSTS and TESS.

There were 591 patients available for analysis. The Pearson correlation coefficients for the association between changes in MSTS and TESS scores and changes in the external anchor scores were 0.71 and 0.57, indicating “high” and “moderate” correlation. Anchor-based MIDs were 12 points and 11 points for the MSTS and TESS, respectively. Distribution-based calculations yielded MIDs of 16-17 points for the MSTS and 14 points for the TESS.

The current study proposes MID scores for both the MSTS and TESS outcome measures based on 591 patients with bone tumors undergoing lower extremity endoprosthetic reconstruction. These thresholds will optimize interpretation of the magnitude of treatment effects, which will enable shared decision-making with patients in trading off desirable and undesirable outcomes of alternative management strategies. We recommend anchor-based MIDs as they are grounded in changes in functional status that are meaningful to patients.

The syndesmosis ligament complex stabilizes the distal tibiofibular joint, while allowing for the subtle fibular motion that is essential for ankle congruity. Flexible fixation with anatomic syndesmosis reduction results in substantial improvements in functional outcomes. New dynamic CT technology allows real-time imaging, as the ankle moves through a range of motion. The aim of this study was to determine if dynamic CT analysis is a feasible method for evaluating syndesmosis reduction and motion following static and flexible syndesmosis fixation.

This is a subgroup analysis of a larger multicenter randomized clinical trial, in which patients with AO 44-C injuries were randomized to either Tightrope (one knotless Tightrope, Group T) or screw fixation (two 3.5-mm cortical screws, Group S). Surgical techniques and rehabilitation were standardized. Bilateral ankle CT scans were performed at one year post-injury, while patients moved from maximal dorsiflexion (DF) to maximal plantar flexion (PF). Three measurements were taken at one cm proximal to the ankle joint line in maximal DF and maximal PF: anterior, midpoint, and posterior tibiofibular distances. T-tests compared Group T and Group S, and injured and uninjured ankles in each group.

Fifteen patients (six Group T [three male], nine Group S [eight male]) were included. There was no difference for mean age (T = 42.8 ± 14.1 years, S = 37 ± 12.6, P = 0.4) or time between injury and CT scan (T = 13 ± 1.8 months, S = 13.2 ± 1.8, P = 0.8). Of note in Group S, seven of nine patients had at least one broken screw and one additional patient had screws removed by the time of their dynamic CT. There was no significant difference between treatment groups for tibiofibular distance measurements in maximal PF or DF. Group T showed no significant difference between the injured and uninjured side for tibiofibular measurements in maximal PF and DF, suggesting anatomic reduction. For Group S, however, there was a significantly larger distance for all three measurements at maximal PF compared to the uninjured ankle (all P < 0 .05).

In all but one Group S patient, screws were broken or removed prior to their dynamic CT, allowing possible increased syndesmotic motion, similar to Group T. Despite this, dynamic CT analysis detected increased tibiofibular distance in Group S as ankles moved into maximal PF when compared with the uninjured ankle. Given the importance of anatomic syndesmosis reduction, dynamic ankle CT technology may provide valuable physiologic information warranting further investigation.

Population-based studies from the United States have reported that sarcoma patients living in rural areas or belonging to lower socioeconomic classes experience worse overall survival; however, the evidence is not clear for universal healthcare systems where financial resources should theoretically not affect access to standard of care. The purpose of this study was to determine the survival outcomes of soft-tissue sarcoma (STS) patients treated in Ontario, Canada over 23 years and determine if the patient's geographic location or income quintile are associated with survival.

We performed a population-based cohort study using linked administrative databases of patients diagnosed with STS between 1993 – 2015. The Kaplan-Meier method was used to estimate 2, 5, 10, 15 and 20-year survival stratified by age, stage and location of tumor. We estimated survival outcomes based on the patient's geographic location and income quintile. The Log-Rank test was used to detect significant differences between groups. If groups were significantly different, a Cox proportional hazards model was used to test for interaction effects with other patient variables.

We identified 8,896 patients with biopsy-confirmed STS during the 23-year study period. Overall survival following STS diagnosis was 70% at 2 years, 59% at 5 years, 50% at 10 years, 43% at 15 years, and 38% at 20 years. Living in a rural location (p=0.0028) and belonging to the lowest income quintile (p<0.0001) were independently associated with lower overall survival following STS diagnosis. These findings were robust to tests of interaction with each other, age, gender, location of tumor and stage of disease.

This population-based cohort study of 8,896 STS patients treated in Ontario, Canada over 23 years reveals that patients living in a rural area and belonging to the lowest income quintile are at risk for decreased survival following STS diagnosis. We extend previous STS survival reporting by providing 15 and 20-year survival outcomes stratified by age, stage, and tumor location.

Introduction

The direct anterior approach (DAA) for total hip arthroplasty continues to gain popularity. Consequently, more procedures are being performed with the patient supine. The approach often utilizes a special leg positioner to assist with femoral exposure. Although the supine position may seem to allow for a more reproducible pelvic position at the time of cup implantation, there is limited evidence as to the effects on pelvic tilt with such leg positioners. Furthermore, the DAA has led to increased popularity of specific softwares, ie. Radlink or JointPoint, that facilitate the intra-op analysis of component position from fluoroscopy images.

The aim of this study was to assess the difference in cup orientation measurements between intra-op fluoroscopy and post-op CT.

Objectives

For patients with Developmental Dysplasia of the Hip (DDH) who progress to needing total joint arthroplasty it is important to understand the morphology of the femur when planning for and undertaking the surgery, as the surgery is often technically more challenging in patients with DDH on both the femoral and acetabular parts of the procedure¹. The largest number of male DDH patients with degenerative joint disease previously assessed in a morphological study was 12². In this computed tomography (CT) based morphological study we aimed to assess whether there were any differences in femoral morphology between male and female patients with developmental dysplasia undergoing total hip arthroplasty (THA) in a cohort of 49 male patients, matched to 49 female patients.

End-stage ankle arthritis (ESAA) is a debilitating disease that does not affect all individuals equally. Gender differences have been identified in patients with end-stage hip and knee arthritis and have stimulated research to explain these findings. The present study was undertaken to examine if gender has a significant effect on pre-operative disability and post-operative outcomes in patients with ESAA.

Patients undergoing ankle arthrodesis (AA) or total ankle replacement (TAR) with minimum 2-year follow-up were identified in the Canadian Orthopaedic Foot and Ankle Society prospective ankle reconstruction database. Demographic data, revision data, patient satisfaction questionnaires, and outcome data using the Ankle Osteoarthritis Scale (AOS) and Short-form 36 (SF-36) health survey were collected.

TAR: 384 patients were included, with 198 females and 186 males. Patient BMI, comorbidities, and duration of follow-up were similar between groups. Males were slightly older at the time of surgery (65.1 vs 62.4 years, p=0.01)). The most common etiology was post-traumatic arthritis for both genders, however females had a higher rate of rheumatoid arthritis (17% vs 5%, p=0.001). Implant types included STAR, Hintegra, and Mobility, and were similar between groups. Preoperatively females had higher rates of pain and disability, demonstrated by lower SF-36 physical component scores (PCS) (31.0 vs 34.5, p<0.001), and higher AOS pain (54.7 vs 51.1, p=0.05) and AOS disability scores (66.5 vs 59.6, p<0.001). Postoperatively, both groups had significant improvement in PCS, AOS pain, and AOS disability scores. Females, however, continued to demonstrate lower PCS scores (38.3 vs 41.9, p<0.001) and higher AOS disability (31.0 vs 25.8, p=0.02) than males. Regression analysis found that preoperative PCS, gender, age, and arthritis etiology all had a significant impact on postoperative PCS scores, with preoperative PCS scores having the largest impact. Preoperative AOS pain and disability scores had the largest impact on postoperative AOS pain and disability scores, respectively. Gender had no significant impact on AOS pain and disability scores postoperatively. Patient satisfaction was similar between males and females postoperatively. Secondary surgery was performed in 13.6% of females and 16.1% of males. Five males and five females underwent revision to arthrodesis.

In patients with ESAA, females tend to have higher pre-operative levels of pain and disability compared to males, which persists post-operatively. This is consistent with the hip and knee arthroplasty literature. This finding may be due to females undergoing surgery at more advanced disease states, arthritis etiology, referral bias, or treatment bias. Both males and females have significant and similar degrees of improvement in pain and disability scores after TAR, and reoperation rates and patient satisfaction rates are similar despite the apparent disparity in outcomes.

Introduction

The Walch Type B2 glenoid has the hallmark features of posteroinferior glenoid erosion, retroversion, and posterior humeral head subluxation. Although our understanding of the pathoanatomy of bone loss and its evolution in Type B's has improved, the etiology remains unclear. Furthermore, the morphology of the humerus in Walch B types has not been studied. The purpose of this imaging based anthropometric study was to examine the humeral torsion in Walch Type B2 shoulders. We hypothesized that there would be a compensatory decrease in humeral retroversion in Walch B2 glenoids.

Distal radius fractures are the most common upper extremity fracture. The incidence is significantly higher in elderly females with osteoporotic bone. When surgery is indicated, volar locking plates (VLPs) allow for rigid fixation particularly in comminuted fractures with poor bone quality. Although numerous studies have shown the importance of plate placement to avoid soft tissue complications associated with volar plate fixation, there has been little evidence on the anatomic fit of current VLPs. Moreover, the effect of gender differences in distal radius morphology on anatomic fitting of VLPs has not been studied. The aim of this study was to evaluate the gender difference in distal radius morphology and the accuracy of the fit of a current VLP to CT-based distal radius models.

Segmented CT models of ten female (mean age, 89 ± 5 years), and ten male (mean age, 86 ± 4 years) cadaveric wrists were obtained. Micro-CT models of the DePuy-Synthes 4-hole extra-articular (EA) and 8-hole volar column (VC) distal radius VLPs were created. A 3D visualization software was used to simulate appropriate plate placement on to the distal radius models by a fellowship-trained hand surgeon. Volar cortical angles (VCA) of the medial, middle and lateral portion of the distal radius were measured and compared between genders. The accuracy of the fit of the two VLP designs were quantified using the percentage of the watershed line (WSL) overlapped by the plate (WSL overlap), the distance between the WSL and the most distal aspect of the posterior plate (prominence distance) and the percentage of contact between the plate and bone.

There were statistically significant gender differences in medial, middle and lateral VCAs (p=.003 medial, p=.0001 middle, p=.002 lateral). VCA ranged from 28° to 36° in females and from 38° to 45° in males. The WSL overlap did not show statistically significant gender differences (male: 5.9%, female: 13.6%, p=.174). However, the difference in prominence distance between different genders approached statistical significance (male: 3.5mm, female: 2.6mm, p=.087). Contact mapping between the plate and bone did not demonstrate a perfect contact in any of our specimens. Thus, contact measurements were categorized into 0.1mm, 0.2mm, and 0.3mm threshold contacts. There were no statistically significant gender differences in any of the threshold categories (0.1mm: p=.84, 0.2mm: p=.97, 0.3mm: p=.99).

Our results confirm that there are gender differences in distal radius morphology. Current plate designs incorporate a VCA of 25° which does not match the native VCA of the distal radius in males or females. Although the difference in prominence distance approached statistical significance, there were no statistically significant gender differences in the WSL overlap or the contact threshold values. This lack of statistical significance may be related to the small sample size. This study proposes novel methods of assessing the anatomic fit of current VLPs in a 3D CT-based model that may be used in future studies with a larger sample size. Moreover, this study demonstrated the importance of considering gender differences in distal radius morphology in the design of future generations of implants.

Introduction

When performing total knee arthroplasty (TKA), surgeons often utilize a posterior-stabilized (PS) design which compensates for the loss of the posterior cruciate ligament (PCL). These designs attempt to replicate normal knee kinematics and loading using a cam and post to provide posterior restraint of the tibia during flexion. However, these designs may not be able to compensate for the increase in flexion space or the inherent loss of coronal stability after PCL release compared to a cruciate retaining (CR) design. This study aimed to compare stability of PS and CR TKA designs by assessing laxity in three planes.

Introduction

Increasingly young and active patients are concerned about revision arthroplasty forcing the manufacturers to think about revision prostheses that fit to this population while meeting the indications and fitting with bone losses and ligament deficiencies. One of those industrials claims that its system allows the surgeon to rise the constraint from a posterior stabilized (PS) prostheses to a semi-constraint total stabilized (TS) prostheses without modifying the gait pattern thanks to a similar single radius design. The aim of the study was to compare gait parameters in patients receiving either PS or TS knee prostheses.

Low back pain is more common in women than men, yet most studies of intervertebral disc (IVD) degeneration do not address sex differences. In humans, there are sex differences in spinal anatomy and degenerative changes in biomechanics, and animal models of chronic pain have demonstrated sex differences in pain transduction. However, there are few studies investigating sex differences in annular puncture IVD degeneration models. IVD puncture is known to result in progressive biomechanical alterations, but whether these IVD changes correlate with pain is unknown. This study used a rat IVD injury model to determine if sex differences exist in mechanical allodynia, biomechanics, and the relationship between them, six weeks after IVD injury.

Procedures were IACUC approved. 24 male & 24 female four-month-old Sprague-Dawley rats underwent a sham or annular puncture injury surgery (n=12 male, 12 female). In injury groups, three lumbar IVDs were each punctured three times with a needle, and injected with tumor necrosis factor-alpha. Mechanical allodynia was tested biweekly using von Frey filaments. Six weeks after IVD injury, rats were euthanized and motion segments were dissected for non-destructive axial tension-compression and torsional rotation biomechanical testing. Two-way ANOVA with Bonferroni corrections identified statistically significant differences (p < 0 .05) and correlations used Pearson's coefficient.

Annular puncture injury induced a significant increase in mechanical allodynia compared to sham in male but not female rats up to six weeks after injury. There was a significant sex effect on both torque range and torsional stiffness, with males exhibiting greater stiffness and torque range than females. Tensile stiffness, compressive stiffness, and axial range of motion showed no sex difference. Males and females showed similar patterns of correlation between variables when sham and injury groups were analyzed together, but correlations were stronger in males. Most correlations were clustered within testing approach: axial biomechanics negatively correlated, torsional biomechanics positively correlated, and von Frey thresholds positively correlated. Surprisingly, mechanical allodynia did not correlate with any biomechanics after injury, and the axial and torsional biomechanics showed little correlation.

This study demonstrates that males and females respond to IVD injury differently. Given the absence of correlation between pain and biomechanics, pain cannot be attributed completely to biomechanical changes. This may explain why spinal fusion surgery, an intervention limited to the spine, has produced inconsistent results and is controversial for patients with low back pain. Thus, in addressing low back pain, we must consider both spinal tissues and the nervous system. Further, the limited correlation between axial and torsional biomechanics indicates that IVD injury may have distinct effects on nucleus pulposus and annulus fibrosus. Biomechanics did not differ between sham and injury at week six, suggesting healing after injury. It remains possible that acute biomechanical changes may initiate chronic pain pathogenesis. We conclude that the observed sex differences demonstrate the need for inclusion of both males and females in IVD injury and pain studies, and suggest that males and females may require different treatments for conditions that appear similar.

Introduction

Tibiofemoral constraint in patients with total knee replacements (TKR) is dependent on both implant geometry and the surrounding soft tissue structures. Choosing more highly constrained geometries can reduce the contribution of soft tissue necessary to maintain joint stability [1]. Often when knee revision surgeries are required, the soft tissue and bone are compromised leading to the use of more constrained implants to ensure knee stability [2]. The current study quantifies the differences in varus-valgus (VV) and internal-external (IE) constraint between two types of total knee revision systems: SIGMA® TC3© and ATTUNE® REVISION.

Knee kinematics are altered by total knee arthroplasty (TKA) both intentionally and unintentionally. Knowledge of how and why kinematics change may improve patient outcome and satisfaction through improved implant design, implant placement or through rehabilitation.

In the present study we imaged and compared the 6 degree-of-freedom (DOF) patellofemoral (PF) and tibiofemoral (TF) kinematics of 9 pre-TKA subjects to the kinematics of 15 post-TKA subjects (Zimmer NexGen LPS implants) using a novel sequential-biplanar radiographic protocol that allowed imaging the postoperative patellofemoral joint under weightbearing throughout the range of motion, which has not been done previously to our knowledge.

There were clear, statistically significant differences between the pre-TKA and post-TKA kinematics: for the TF joint, the tibia was more posterior and inferior (max 20 mm and 15 mm, respectively) in the post-TKA group compared to the pre-TKA group (p<0.001), and had neutral alignment in the post-TKA group compared to varus alignment (max 9°) in the pre-TKA group (p<0.001). For the PF joint, the patella was shifted more posteriorly and medially, and tilted more medially in the post-TKA group compared to the pre-TKA group (p<0.001). There were no significant differences in PF superior/inferior translation and flexion/extension (p>0.5). Both groups showed differences from normal kinematics, based on the literature.

The kinematic differences are likely due to a combination of surgical, implant and patient factors. To investigate this further, we imaged the 9 pre-TKA subjects a minimum one year after their surgery; analysis of these data is in progress. Computed tomography (CT) scans and quality of life surveys were also taken before and after surgery. By comparing the preoperative and postoperative kinematics and shape for the same subjects, and analysing the interrelationships amongst these, we aim to determine if a different implant shape or different component positioning could create more normal kinematics, resulting in a better clinical outcome.

Introduction

Previous anthropometric studies have reported gender differences in distal femoral morphology. After total knee arthroplasty, females have a higher prevalence of medial or lateral femoral component overhang, which could be responsible for postoperative knee pain and decreased range of motion. Consequently, gender-specific knee prostheses were designed to accommodate female morphology. However, to date, very few studies have investigated the knee morphology of Japanese adults and possible gender differences. The purpose of this study was to examine the distal femoral morphology of Japanese patients, to characterize anatomical differences between men and women, and to evaluate the need to create gender-specific knee prostheses.

Background

More and more patients with end-stage knee OA are treated with total knee replacements (TKR). A modern TKR (Persona PS system, Zimmer Inc.) was designed with the hope to improve fit by providing additional sizing options on the femur and tibia. To date, there is very little information regarding the knee strength and knee mechanics during gait after the TKR. Furthermore, as a great percentage of knee OA patients have OA limited in one knee compartment and in the patellofemoral joint, a bi-compartmental knee replacement (BKR) (iDUO system, ConforMIS Inc.) was designed to treat OA at these affected areas. The BKR re-creates the individual's knee shape while correcting for any deformity. In addition, the BKR procedure results in less bone loss and retains the cruciate ligaments. To date, the influence of the BKR on knee strength and knee mechanics remains unknown. The purpose of the study was to evaluate knee strength and mechanics during level walking after the TKR and BKR surgeries.