Post impingement in posterior stabilised total knee arthroplasty.

Posterior stabilised implants are a well-proven treatment for patients requiring primary total knee arthroplasty. Concerns about the posterior stabilised (PS) design have been raised and recent studies suggest that the post-cam articulation can be an additional source of polyethylene wear debris. In this study, the authors report impingement of the tibial post against the patellar component in deep flexion in posterior stabilised total knee arthroplasty. Their data suggest that "post impingement" is associated with a raised joint line, patella infera, too anterior placement of the tibial component and a smaller femoral component size. "Post impingement" may lead to extensor mechanism problems and additional polyethylene wear and therefore may affect the longterm functional results of posterior stabilised total knee arthroplasty.