Comparison of High-Flexion and Conventional Implants in Total Knee Arthroplasty: A Meta-Analysis

BACKGROUND: The purpose of this study was to evaluate whether high-flexion prostheses are superior to conventional prostheses after total knee arthroplasty (TKA). MATERIAL/METHODS: We searched the PubMed and Embase databases for randomized trials and cohort studies comparing high-flexion with conventional knee implants. The heterogeneity across studies was examined by I(2) and Cochran’s Q-tests. Then the overall weighted mean differences of range of motion (ROM) and knee functional scores were evaluated. RESULTS: A total of 16 trials involving 2643 knees met our inclusion criteria. The results revealed that high-flexion implants were superior to conventional implants in the improvement of range of motion (weighted mean difference, 2.92; 95% CI, 1.63–4.22; p<0.0001). The clear advantage of high-flex PS (posterior stabilized) as well as high-flex CR (cruciate retaining) implants was found in ROM when compared to PS implants (2.73; 95% CI, 1.27–4.20; p=0.0003) and CR implants (3.24; 95% CI, 0.28–6.20; p=0.003), respectively. However, there was no difference in Knee Society Scores (0.42; 95% CI, −0.60–1.43; p=0.42), Knee Society function (0.37; 95% CI, −1.48–2.22; p=0.70) and Hospital for Special Surgery scores (0.26; 95% CI, −0.47–1.00; p=0.48) between high-flexion and conventional groups. CONCLUSIONS: The current meta-analysis revealed that high-flexion implants were superior to conventional implants in the improvement of ROM but not in functional outcome scores.