Comparison of Gait Characteristics Between Patients With Nontraumatic and Posttraumatic Medial Knee Osteoarthritis.

OBJECTIVE To compare knee kinematics and kinetics during walking in patients with posttraumatic versus nontraumatic medial compartment knee osteoarthritis (OA). METHODS Participants with medial compartment knee OA were classified as nontraumatic (n = 122) or posttraumatic (n = 93) based on evidence of previous anterior cruciate ligament tear, confirmed arthroscopically. Kellgren/Lawrence severity scores and mechanical axis angle (MAA) were determined from radiographs. Knee flexion and adduction angles and external moments were calculated from gait analysis using a 3-dimensional optical motion capture system and force plate. Peak values were identified and principal component (PC) analysis determined waveform characteristics (PC scores). Linear regression models examined whether the OA group (posttraumatic or nontraumatic) predicted peak values and PC scores after controlling for age, gait speed, and severity. Models were repeated with and without controlling for MAA. RESULTS The knee OA group was a significant predictor of peak knee adduction angles (P = 0.04) and moments (P = 0.05). Similarly, it was a significant predictor for some knee adduction angle (P = 0.02 to 0.64) and moment (P = 0.02 to 0.25) PC scores. The nontraumatic OA group had higher adduction angles and moments. There were no significant relationships between OA group and knee flexion angles and moments. After controlling for MAA, only one significant relationship remained between knee adduction moment shape characteristics and OA group. CONCLUSION Frontal plane knee kinematics and kinetics during walking differ between patients with posttraumatic versus nontraumatic medial compartment knee OA, with posttraumatic OA showing relatively decreased adduction.