Profile imaging can be used to image the articulation of the patellofemoral joint of total knee implants. Using undamaged implants, conformity of the two articulating surfaces could be traced at angles of 50, 70, 90, and 120° of knee flexion. This was applied to five different styles of implants.
Femoral and patellar implants were retrieved from 40 patients undergoing revision total knee arthroplasty (TKA). Only all-polyethylene dome-shaped components were selected. Patellar implants were studied and graded for evidence of wear. Conformity data were then compared with wear data to assess the possible relationships between design parameters and subsequent wear.
Statistically significant differences in wear could be identified as they related to conformity of the articulating surfaces. Sharp patellofemoral edges and carbon-reinforced polyethylene (CRPE) patellar components were a particularly worrisome combination.
Profile imaging is a useful additional tool for assessing design features of implants and their subsequent relationships to implant-generated wear debris.