Bearing thickness of unicompartmental knee arthroplasty is a reliable predictor of tibial bone loss during revision to total knee arthroplasty

Hinge prostheses in the revision of unicompartmental knee replacement: a descriptive analysis of data from the national joint registry for England, Wales and Northern Ireland

INTRODUCTION

Unicompartmental knee replacement (UKR) is an effective surgical strategy in patients with isolated medial or lateral compartment osteoarthritis. Study aims were to (1) describe the epidemiology of patients undergoing revision of UKR to a hinge knee replacement (HKR); (2) identify factors influencing time to revision; (3) evaluate HKR survival.

MATERIALS AND METHODS

An analysis of National Joint Registry data was undertaken, exploring revision of UKR to HKR between 2007 and April 2021. Descriptive analysis of eligible patients and Cox Regression to identify key determinants of time to revision were performed. Failure of HKR post-revision was assessed using survival analysis.

RESULTS

111 patients underwent revision of UKR to HKR. Median age at revision was 70 years and most common indications were instability (n = 42) and infection (n = 22). The most common implant was a rotating HKR. Significant independent factors associated with earlier revision were periprosthetic fracture (p = 0.03) and malalignment (p = 0.03). Progressive osteoarthritis (p = 0.01) and higher ASA grades (3: p = 0.01, 4: p < 0.01) delayed time to revision; patient sex and age were not significant factors. Ten patients required subsequent re-revision; median age at re-revision was 61 years. HKR revised from UKR had an 89.3% revision-free risk at 5 years. Male sex (p < 0.01) and younger age (p < 0.01) were associated with re-revision.

CONCLUSIONS

Factors associated with time to revision may be used to counsel patients prior to UKR. The survivorship of the HKR of 89.3% at 5 years is concerning and careful consideration should be given when using this level of constraint when revising UKR in younger or male patients.

Clinical Outcomes of Revision Total Knee Arthroplasty after High Tibial Osteotomy and Unicompartmental Knee Arthroplasty: A Systematic Review and Meta-Analysis

As more high tibial osteotomy (HTO) and unicompartmental knee arthroplasty (UKA) are performed, orthopaedic surgeons realize that more HTO and UKA failures will require revision to total knee arthroplasty (TKA) in the future. To systematically evaluate the clinical outcomes of TKA after HTO and TKA after UKA, the Embase, PubMed, Ovid, Web of Science, and Cochrane Library databases were searched for studies investigating revision TKA after HTO and UKA published up to June 2021. RevMan version 5.3 was used to perform the meta‐analysis. The revision TKA after HTO and revision TKA after UKA groups were compared in terms of operative time, range of motion (ROM), knee score, postoperative complications, postoperative infection, revision, and revision implants used. Nine studies were ultimately included in the meta‐analysis. Results revealed that the knee score for the revision TKA after HTO group was better than that of the revision TKA after UKA group (MD 4.50 [95% CI 0.80–8.20]; p = 0.02). The revision TKA after HTO group had a lower revision rate (OR 0.65 [95% CI 0.55–0.78]; p < 0.00001) and fewer revision implants used (OR 0.11 [95% CI 0.05–0.23]; p < 0.00001). There were no statistical differences in operation time (MD ‐2.00 [95% CI −11.22 to 7.21]; p = 0.67), ROM (MD ‐0.04 [95% CI ‐3.69–3.61]; p = 0.98), postoperative complications (OR 1.41 [95% CI 0.77–2.60]; p = 0.27), or postoperative infections (OR 0.89 [95% CI 0.61–1.29]; p = 0.53). To conclude, the revision rate of revision TKA after UKA was greater, and more revision implants were required. It is important for orthopaedic surgeons to preserve bone during primary UKA.

Finite Element Analysis Contact Stresses on Tibiofemoral Joint and Post Polyethylene Components Used to Evaluated Predesign Knee Implant

At the time of prayer, most Muslims kneel with fully extended limbs (between 150° and 165°). Meanwhile, incidents such as hyperflexion in total knee arthroplasty (TKA) implant outside their designated configuration can lead wear or fracture of the polyethylene component. In this study, polyethylene component of posterior-stabilized right knee joint implant have been developed to facilitate higher range of motion (ROM). Finite element analysis (FEA) was used to analyze contact stresses on the polyethylene component. FEA was used to simulate weight-bearing condition at 0°, 30°, 60°, 90°, 120°, and 150° of knee flexion. Modified polyethylene component results in better performance in terms of contact stresses, especially at 120° of knee flexion. Current result shows contact stresses above 120 MPa were measured at the posterior post polyethylene, when 4000 N force was applied. Minimum contact stress on the medial condyles was 630 KPa at 120° of knee flexion, while on the lateral condyles, the minimum contact stress was 250 KPa at 150° of knee flexion. With this finding, the current polyethylene component design is expected to accommodate deep knee flexion movement in daily activities and can reduce potential of wear or fracture of the polyethylene component during deep knee flexion.

Lower early revision rates after uncemented Oxford Unicompartmental Knee Arthroplasty (UKA) than cemented Oxford UKA: A meta-analysis

BACKGROUND

UKA has been proved to offer good results in treating patients with unicompartmental knee osteoarthritis (OA). However, there is still a controversy about the better fixation mode in UKA procedure between cemented and uncemented prosthesis. Therefore, this meta-analysis was conducted to compare clinical and radiological outcomes of cemented versus uncemented Oxford UKA.

HYPOTHESIS

The study surmised that uncemented Oxford UKA was associated with shorter operation time, higher function scores, lower revision rate and less radiolucency than cemented Oxford UKA.

METHODS

A meta-analysis to compare postoperative outcomes between cemented and uncemented Oxford UKA wsa conducted. The primary outcomes included Oxford knee score (OKS), revision rate, and incidence of radiolucency. The secondary outcomes included operation time, knee society score (KSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), range of motion (ROM). PubMed, Embase, Web of Science, the Cochrane Library and China national knowledge infrastructure were searched until April, 2020 to identify studies for including. Relevant data were analyzed using RevMan v5.3.

RESULTS

We identified nine studies involving 901 patients meeting our inclusion criteria. No significant difference of OKS was found in both groups. Compared with cemented group, uncemented Oxford UKA group was associated with lower revision rate (95% CI: 0.90 to 3.73; OR=1.83) and less radiolucent lines (95% CI: 0.79 to 9.52; OR=2.75) after following up for at least 2years. The operation time was significantly shorter by 10.12minutes (95% CI: p<0.00001) in the uncemented group when compared against the cemented group. The KSS, WOMAC, ROM were not significantly different between two groups.

CONCLUSIONS

Uncemented Oxford UKA had lower revision rate, shorter operation time and less radiolucent lines than cemented Oxford UKA did. There is still need for more long follow-up clinical trials with high evidence level to determine which method of fixation is of preferable for Oxford UKA in the future.

LEVEL OF EVIDENCE

I.