Capsular release around the intercondylar notch increases the extension gap in posterior-stabilized rotating-platform total knee arthroplasty

•Various post-cam designs can be used in posterior-stabilized total knee arthroplasty (TKA).•A larger cam of the femoral component may tighten the extension gap.•We assess the effect of capsular release around the intercondylar notch on the extension gap.•Capsular release increases the extension gap and may prevent postoperative flexion contracture.•Our method provides intraoperative flexion contracture in posterior-stabilized TKA.

BackgroundIn posterior-stabilized (PS) total knee arthroplasty (TKA), various post-cam designs can be used. A larger cam of the femoral component may tighten the extension gap. Few studies have investigated the relationship between capsular release around the intercondylar notch and the extension gap. The aim of this study was to assess the effect of capsular release around the intercondylar notch on the extension gap.MethodsForty-eight patients (54 knees) who underwent PS rotating-platform TKA (PFC Sigma RP-F) were enrolled retrospectively. We measured the extension gap with and without a femoral trial using a knee balancer, applying a joint distraction force of 44 lb. When an intraoperative flexion contracture of > 5° persisted, we performed a capsular release approximately 10 mm cranial to the intercondylar notch. After full knee extension was achieved, the extension gap was measured again.ResultsThirty knees required capsular release. With a trial, the medial and lateral differences between the extension gaps before and after capsular release were 1.7 mm (p < 0.0001) and 2.3 mm (p < 0.0001), respectively. Without a trial, the gaps were enlarged by 0.4 mm (p = 0.0452) and 0.6 mm (p = 0.0215), respectively. Twenty-four knees did not require release. No significant differences were noted in the range of motion at one-year follow-up between the two cohorts.ConclusionsWith PS rotating-platform TKA, capsular release around the intercondylar notch is found to increase the extension gap and may prevent postoperative flexion contracture.Level of EvidenceLevel III, retrospective comparative study.