Posterior capsular release around the intercondylar notch increases extension gap without affecting flexion gap in posterior-stabilized total knee arthroplasty.

Abstract

In posterior-stabilized (PS) total knee arthroplasty (TKA), joint extension gap decreases after placement of a femoral trial component which causes imbalance between the extension and flexion gaps. Previous studies have demonstrated that capsular release around the intercondylar notch can enlarge the extension gap; however, its impact on the flexion gap is unknown. This study assessed the effect of capsular release around the intercondylar notch on both extension and flexion gaps. This study included 100 patients who underwent PS-TKA, and capsular release was performed intraoperatively to avoid flexion contracture and to balance the extension-flexion gap. We measured the gap and tilting angle with a femoral trial using FuZion™ tensor, applying a joint distraction force of 40 lbs. The differences in gap and tilting angle were assessed before and after capsular release. The mean center component gap (CG) before and after capsular release was 10.0 mm and 12.5 mm in extension (P < 0.001), 14.1 mm and 14.2 mm in flexion (P = 0.58), respectively. Calculated medial CG before and after capsular release was 9.2 mm and 11.4 mm in extension (P < 0.001), 12.6 mm and 12.7 mm in flexion (P = 0.20), respectively. The average medial CG difference significantly decreased from 3.4 mm to 1.3 mm after release. This study confirmed that capsular release around the intercondylar notch significantly enlarges the extension component gap, while having an insignificant effect on the flexion component gap in PS-TKA.