Effect of Medial Soft Tissue Releases During Posterior-Stabilized Total Knee Arthroplasty on Contact Kinematics and Patient-Reported Outcomes

BACKGROUND: Minimal to extensive medial soft tissue releases are part of the exposure and achieving adequate varus knee balance in total knee arthroplasty (TKA). However, the effect of these releases on knee kinematics and patient-reported outcomes is unclear. Our objective was to compare the postoperative in vivo tibiofemoral contact kinematics of a posterior-stabilized TKA between patients who received minimal medial soft tissue releases intraoperatively to those who received extensive releases. We also compared these groups using patient-reported outcomes. METHODS: A prospective imaging study was performed in a single-center over a 14-month period. Patients with end-stage osteoarthritis and varus deformity undergoing primary TKA were included. Baseline data were collected 1 month before surgery. The radiostereometric analysis imaging took place at least 1 year postoperatively and composed of weight-bearing radiographic stereo examinations of knee flexion starting in full extension and in 20° increments of flexion to a maximum of 120°. Intraoperative medial soft tissue releases were recorded. Patient-reported outcomes used included Short-Form 12, Western Ontario and McMaster Osteoarthritis Index, and Knee Society Score. RESULTS: Fifty-one patients were included in the statistical analysis. Demographic characteristics were similar between all. Patients were divided into 3 groups depending on the amount of releases they received. No statistically significant differences in tibiofemoral contact positions or excursions on the medial or lateral condyles were found throughout flexion from 0° to 120°. Postoperative patient-reported outcome scores were not different. CONCLUSION: Correcting severe varus deformities with extensive medial soft tissue release largely did not alter knee kinematics or clinical outcome scores compared to those with minimal soft tissue release.