Kinematics in osteoarthritic knees may be impeding efforts to reproduce "normal" knee kinematics in the prosthetic knee. Fourteen subjects with unilateral symptomatic knee osteoarthritis performed a supine leg press from 0° to 90° flexion against a 150-N load. The tibiofemoral contact pattern was recorded for both knees using sagittal T1-weighted magnetic resonance imaging. Severity of osteoarthritis ranged from Kellgren Lawrence grade 2 to 4 in the symptomatic knees and from 0 to 3 in the contralateral knees. Contact in the lateral and medial compartments of osteoarthritic knees was more anterior on the tibial plateau than healthy knees, both in knee extension and to 90° flexion (P < .01). This anterior contact pattern was associated with severity of osteoarthritis (P < .01).