Early Outcomes of Kinematic Alignment in Primary Total Knee Arthroplasty: A Meta-Analysis of the Literature

Background: Kinematic alignment in total knee arthroplasty (TKA) seeks to more anatomically align the knee prosthesis to promote more physiological kinematics. However, there are questions about the durability, function, and complication rate of a nonemechanically aligned TKA. Therefore, the purpose of this study is to perform a systematic review and meta-analysis to evaluate early outcomes after kinematic alignment. Methods: Two independent reviewers performed a systematic review of the English literature using both the MEDLINE and Embase databases searching for studies on kinematic TKA. Of the initial 839 published reports, 9 studies were included in the review. Four randomized, controlled trials comparing outcomes of kinematic and conventional alignment TKA were identified. Data were extracted and aggregated using inverse variance and Mantel-Haenszel fixed effects meta-analysis. Results: Of an aggregated 877 kinematic TKAs, the cumulative survivorship was 97.4% at a weighted mean follow-up of 37.9 months. The most common reasons for revision were patellofemoral problems in 8 patients (1.2%). We found no difference in the complication rate between the 229 kinematic and 229 conventional TKA patients (3.9% vs 4.4%; P=.83). The kinematic TKA group had a higher combined postoperative Knee Society Score than the conventional TKA group (mean difference, 9.1 points; 95% confidence interval, 5.2-13.0 points; P<.001). Conclusion: Small deviations from the traditional mechanical axis alignment in TKA do not appear to impact overall survivorship or complication rates at short-term follow-up. Functional outcome as measured by the Knee Society Score favored kinematic alignment. These preliminary results illustrate the concept that there may be more than a single alignment target for all patients undergoing primary TKA. (C) 2017 Elsevier Inc. All rights reserved.