Abstract
PurposePosterior capsular contracture causes stiffness during knee extension in knee osteoarthritis. Furthermore, in posterior-stabilized total knee arthroplasty (PS-TKA), a unique design such as the cam mechanism could conflict with the posterior capsule (PC) causing flexion contracture (FC). However, few studies have focused on the anatomical aspects of the PC. This study aimed to investigate the anatomical site and forms of posterior capsular attachment to the femoral cortex, and to evaluate the efficacy of posterior capsular release for FC by assessing changes in knee extension angles using a navigation system.MethodsAttachment sites of the PC were investigated in 10 cadaveric knees using computed tomography. PS-TKA was performed in six cadaveric knees using a navigation system to evaluate the efficacy of posterior capsular release for FC. Posterior capsular release was performed stepwise at each part of the femoral condyle.ResultsThe gastrocnemius tendon and PC were integrally attached to the femoral cortex at the medial and lateral condyles, whereas the PC at the intercondylar fossa was independently attached directly to the femoral cortex. Moreover, the PC at the intercondylar fossa was attached most distally among each femoral condyle. Posterior capsular release at the intercondylar fossa allowed 11.4° ± 2.8° improvement in knee extension. This angle was further improved by 5.5° ± 1.3°, after subsequent capsular release at the medial and lateral condyles.ConclusionThe forms and sites of posterior capsular attachment differed based on the part of the femoral condyle. Stepwise posterior capsular release was effective for FC in PS-TKA.Level of evidenceIII.
Highlights
Total knee arthroplasty (TKA) aims to relieve severe pain and modify limb alignment to improve patients’ quality of life
The gastrocnemius tendon and posterior capsule (PC) were integrally attached to the femoral cortex at the medial and lateral condyles, whereas the PC at the intercondylar fossa was independently attached directly to the femoral cortex
Stepwise posterior capsular release was effective for flexion contracture (FC) in posterior-stabilized total knee arthroplasty (PS-TKA)
Summary
Total knee arthroplasty (TKA) aims to relieve severe pain and modify limb alignment to improve patients’ quality of life. Intraoperative flexion contracture occurs even with accurate bone resection and optimal management of soft tissues as planned preoperatively. The intraoperative extension gap is related to the postoperative knee extension angle [18]. Previous studies have demonstrated the efficacy of additional distal femoral bone cutting to improve the extension gap and intraoperative knee extension angle [2, 11]. Posterior clearance affects the postoperative knee extension angle. There is no consensus on the type of adjunctive surgical procedure preferred to improve flexion contracture with an optimal soft tissue balance. Little attention has been paid to the actual efficacy of posterior capsular release for knee extension angle in comparison with other surgical methods to improve flexion contracture. A better understanding of the anatomical form and sites of the PC of the knee joint would facilitate posterior capsular release
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