Patellofemoral kinematics after limited resurfacing of the trochlea.

Patellofemoral kinematics after a limited resurfacing of the trochlea was investigated. Patellofemoral contact pressure, area, and force were measured for intact state; after creation of a 20-mm full-thickness trochlear defect; and after trochlear resurfacing implant (Arthrosurface) in serial flexion positions (45 degrees, 60 degrees, 75 degrees). In the defect state, edge loading and peak contact forces were highest at the periphery. The chondral defect increased peak contact force (13 to 18 N, P < .01) and peak contact pressure (23 to 31 kg/cm2, P < .02) compared with the intact state. Peak contact pressure and force were restored to 90% (P < .01) and 88% (P < .01). Implantation of the device restored contact area to 85% of the intact state. Limited resurfacing of the trochlea restores contact area, peak pressure, and peak force to the intact state. These findings highlight the potential clinical use of limited patellofemoral resurfacing in trochlear chondral defects.