Polyethylene damage and knee kinematics after total knee arthroplasty

This study characterizes the relationship between in vivo knee kinematics a nd polyethylene damage by combining fluoroscopic analysis of tibiofemoral c ontact during dynamic activities and implant retrieval analysis in the same patients. Six patients (eight knees) underwent posterior cruciate ligament -retaining total knee arthroplasty. All patients participated in fluoroscop ic analysis during a stair-rise and descent activity and treadmill gait an average of 18 months after arthroplasty, and articular contact was measured . Subsequently, all polyethylene tibial inserts were retrieved after an ave rage of 26 months in vivo function: three at autopsy and five at revision. There was a statistically significant correlation between the damage locati on on the retrieved inserts and the articular contact location measured flu oroscopically during the activities. The femoral contact and polyethylene d amage occurred predominantly on the posterior half of the tibial articular surface, and the damage pattern was largest in the compartment with the gre atest range of in vivo femoral contact for each patient. This study showed that in vivo fluoroscopic analysis can predict the damage location on the p olyethylene articular surface.