Important factors affecting quality of life (QOL) after total knee arthroplasty (TKA) include postoperative knee kinematics and geometry, influenced by implant design and placement (Matsuda 2001; Nishikawa 2013; Noble 2005). Although specific design factors and their effect on kinematics or QOL have been investigated previously, the inter-relationships between preop-postop changes in kinematics, geometry and the resulting QOL have not been studied to our knowledge. These are essential to understand the interplay between the different factors, and to determine which factors manufacturers and surgeons should focus on when designing and implanting knee prostheses. In addition, the majority of TKA studies focus on the tibiofemoral (TF) joint, although the patellofemoral (PF) joint is routinely the source of postop complications; the PF joint is difficult to study due to polyethylene radio-transparency and because the femoral component obscures the patella from most directions.

The purpose of this pilot study was to correlate changes in knee articular shape, over which the implant designers and surgeons have some control, to changes in kinematics and postop QOL, with a particular focus on the PF joint, to answer the following research questions for a sample population with a given implant design and surgeon: (1) Do changes in knee shape affect knee kinematics? In particular, is patellar tracking affected by groove location? (2) Do changes in knee kinematics affect QOL? (3) Do changes in knee shape (resulting from implant design and placement) affect QOL? (4) Do individuals with worse QOL differ from those with better QOL?

Summary Statement

A large proportion of knee arthroplasty patients are dissatisfied with their replacement. Significant differences exist between preoperative, postoperative and normal kinematics. A better understanding of the inter-relationships between kinematics, shape and prosthesis placement could lead to improved quality of life.