Repeatability and precision of a weighted centroid method for estimating dynamic in vivo tibiofemoral surface interactions in sheep.

Persistent changes in joint biomechanics resulting from knee injury are thought to contribute to progressive cartilage damage and post-traumatic osteoarthritis (PTOA). The identification and quantification of in vivo tibiofemoral surface interactions are critical to understanding them, particularly abnormal interactions that are damaging to articular cartilage and other structures of the knee. In this study, we describe an approach for understanding such potential interactions by using a weighted centroid derived from in vivo stifle kinematics in sheep. Collectively, repeatability and sensitivity analyses indicate that the magnitude of the changes in tibiofemoral centroid location resulting from combined ligament transection is greater than the repeatability and precision of the current weighted centroid approach, making this method useful for describing the changes in dynamic surface interactions that may be relevant in the pathogenesis of PTOA in this stifle injury model.