Effect of posterior capsular release on intraoperative joint gap mismatch in the mid-flexion range during posterior-stabilized total knee arthroplasty

Introduction: Intraoperative mismatch between extension and mid-flexion joint gaps remains a critical issue in posterior-stabilized total knee arthroplasty (PS-TKA). Posterior capsular release has been found to increase the extension joint gap. However, there is still a lack of robust evidence for the effect of posterior capsular release on the mid-flexion joint gap. The purpose of the present study was to quantify the effect of posterior capsular release on the intraoperative joint gap from extension through 45 degrees mid-flexion to flexion and to clarify how this procedure might affect the improvement of gap mismatch in the mid-flexion 45 degrees range. Materials and methods: In total, 38 consecutive cases of primary PS-TKA were reviewed. The center, medial, and lateral component gaps from extension to flexion were measured with a tensor device before and after posterior capsular release. The minimal detectable change for joint gap measurement was calculated using two methods, error variance and intra-observer intraclass correlation coefficients. Pre- and post-release joint gap differences were assessed using the paired t-test. Results: Minimal detectable change was found to be 0.59 mm. At 0 degrees and 10 degrees of flexion, the post-release center, medial, and lateral component gaps were significantly greater than at pre-release. At 45 degrees and 90 degrees and maximum flexion, there were no joint gap differences exceeding the minimal detectable change. The joint gap mismatches between 0 degrees and 10 degrees, and 45 degrees, 90 degrees and maximum flexion were significantly smaller at post-release than those at pre-release with the change values exceeding the minimal detectable change (P < 0.05). Conclusion: Posterior capsular release significantly decreased both joint gap mismatch between extension and 45 degrees mid-flexion, and extension and flexion, showing clinical usefulness in PS-TKA. (c) 2022 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.