Influence of soft tissue balancing and distal femoral resection on flexion contracture in navigated total knee arthroplasty

The purpose of this study was to evaluate the influence of intra-operative soft tissue balancing and distal femoral cutting on flexion contracture in navigated TKA. This was a prospective cohort study. Fifty-nine patients of primary navigation-assisted TKA were included with over 15A degrees of flexion contracture and excluded valgus knees. Among the cases, 43 cases were performed with soft tissue balancing procedures only, and 16 cases were performed with soft tissue balancing and additional distal femoral bone cutting. The mean preoperative flexion contracture was 17.5A degrees A +/- 2.7A degrees. The angles of flexion contracture were recorded at each surgical step with navigation. The mean difference in flexion contracture angle between initial angle and angle after medial release was 5.2A degrees A +/- 2.8A degrees. The mean difference in flexion contracture angle between medial release step and after posterior cruciate ligament (PCL) release was 2.5A degrees A +/- 2.2A degrees. The mean difference in flexion contracture angle between PCL release step and after routine bone cutting was 3.1A degrees A +/- 3.2A degrees. The mean difference in flexion contracture angle between after trial insertion and after posterior clearing procedure was 2.7A degrees A +/- 1.9A degrees. Among the cases, TKA with 2 mm additional bone cutting were performed in 16 cases. The mean difference in flexion contracture angle after additional femoral bone cutting was 4.8A degrees A +/- 2.1A degrees. The medial release and 2 mm additional bone cutting could correct flexion contracture by 5A degrees. The appropriate soft tissue balancing and bone cutting could correct flexion contracture intra-operatively up to 5A degrees in each step. II.