A Comparison of Mobile- and Fixed-Bearing Unicompartmental Knee Arthroplasties in the Treatment of Medial Knee Osteoarthritis: A Systematic Review and Meta-analysis of 1,861 Patients

Abstract

Many studies have compared mobile-bearing (MB) and fixed-bearing (FB) unicompartmental knee arthroplasties (UKAs) in patients with unicompartmental knee osteoarthritis (OA). The present systematic review and meta-analysis examined the differences in the clinical and radiological outcomes of MB UKA and FB UKA. PubMed, EMBASE, and Cochrane databases, as well as Google Scholar were searched for relevant studies. Randomized controlled trials (RCTs) and cohort studies that compared MB UKA and FB UKA were included. The weighted mean difference in the knee scores and range of motion (ROM) as well as the summary odds ratio of postoperative mechanical axis alignment, radiolucency, revision rate, and complications were calculated in the MB UKA and FB UKA groups. Finally, 2 RCTs and 11 cohort studies that involved 1,861 patients (1,996 knees) were included. The FB UKA group showed better postoperative Knee Society score (KSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and ROM than the MB UKA group. However, the MB UKA group had more knees with a neutral limb alignment and a lower incidence of polyethylene wear than the FB UKA group. No significant differences were observed between the groups with respect to radiolucency, revision rate, and complications, such as arthritis progression, aseptic loosening, and postoperative pain. This meta-analysis has demonstrated that both prostheses provided excellent clinical outcomes and survivorship in patients with unicompartmental knee OA. The MB UKA group achieved the expected postoperative neutral limb alignment as compared with the FB UKA group, while the FB UKA group showed higher knee scores and superior ROM than the MB UKA group. Limited evidence is currently available; therefore, the results of our meta-analysis should be interpreted with caution.

Bone-on-Bone Contact on Radiograph is not a Prerequisite for Successful Outcome in Fixed-Bearing Medial Unicompartmental Knee Arthroplasty—A 10-Year Follow-Up Study

“…Our findings contradict current knowledge about mobile-bearing UKAs in the literature where the consensus advises against performing UKAs in knees without full thickness loss of joint space. 6 7 In current literature, only the meta-analysis performed by Huang et al 29 showed that fixed-bearing UKAs had better Knee Society scores than mobile-bearing UKAs, but no other studies provide a good explanation for this finding in our study. Unfortunately, our study was unable to elucidate the cause for the differences in FSC and we postulate that this is likely attributed to differences in preoperative functional status.…”

Unicompartmental knee arthroplasty, an enigma, and the ten enigmas of medial UKA

“…The rate of bearing dislocation ranges from 0.6% to 6.5% in different studies [ 101 , 103 ]. Overrelease of medial collateral ligament, undersized bearing, component malposition, and flexion–extension imbalance are some of the causes of bearing dislocation [ 104 ]. Consequently, surgeons tend to keep the medial joint space of the knee tight so that bearing does not slip out.…”

Survivorship of fixed vs mobile bearing unicompartmental knee replacement: A systematic review and meta-analysis of sixty-four studies and National Joint Registries

“…Other reviews focused on either medial or lateral only UKRs with limited study inclusion potentially limiting the usefulness of their findings [14][15][16][17][18][19]. Therefore, the aim of this study was to address the issue of limited inclusion of studies and registries in previous reviews and complement their findings through a comprehensive systematic review and meta-analysis of the implant survival in mobile versus fixed bearing UKR for medial as well as lateral constructs, using all available cohort studies with long-term follow up and registry data with minimal restriction from the past 15 years.…”