Center of Pressure of Medial Knee Contact Force Predicts Future Transition Risk of Knee Surgery in Patients with Knee Osteoarthritis.

purposeThis study aimed to explore whether mechanical load features, including the magnitude of the medial knee contact force (KCFmed) and its center of pressure (KCFcop) during gait, predict future surgery in patients with knee osteoarthritis (OA).

methodsTwenty-six patients with knee OA walked three times at a comfortable speed, and the external knee adduction moment (KAM), flexion moment (KFM), and total knee moment of the KAM and KFM (KTM) were assessed. We further evaluated KCFmed and KCFcop using a musculoskeletal model. The values of knee moments and KCFmed were extracted at the first and second peaks, and the average KCFcop location and amount of KCFcop displacement were calculated during the early-, mid-, and late-stance phases. Ten years after data collection, we confirmed whether the patients required knee surgery (Surg_OA) or not (NonSurg_OA).

resultsTwenty-four patients with complete data were divided into Surg_OA and NonSurg_OA groups. The Surg_OA group had significantly lower KTM, KFM, and KCFmed values at the first peak than the NonSurg_OA group. In the Surg_OA group, KCFcop shifted toward the joint center during the mid- and late-stance phases, and the amount of KCFcop displacement was small during the mid-stance phase. No significant differences were observed in the other parameters.

conclusionOur findings demonstrated that individuals who underwent knee surgery within 10 years showed suppressed KCFmed magnitudes in the first half of the stance phase, whereas they received sustained force on a localized area of the medial compartment during the mid-stance phase.