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

Background: 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.

Methods: 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.

Results: 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.

Conclusion: 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.