Biomechanical Analysis of the Influence of Trochlear Dysplasia on Patellar Tracking and Pressure Applied to Cartilage

Abstract

Trochlear dysplasia is characterized by a shallow trochlear groove providing limited articular constraints to resist lateral forces applied to the patella by the quadriceps muscles and patellar tendon. Trochlear dysplasia is commonly noted for knees being treated for patellar dislocations and is associated with development of patellofemoral osteoarthritis. Of the numerous surgical options available for patellar stabilization, groove-deepening trochleoplasty is the primary approach to directly address trochlear dysplasia. Numerous biomechanical studies have been performed to evaluate the influence of trochlear dysplasia and groove-deepening trochleoplasty on patellar tracking, stability and pressure applied to cartilage. The studies are based on in vitro simulation of knee function, functional imaging of patients and control subjects, and computational simulation of knee function. Functional imaging and computational simulation studies indicate that trochlear dysplasia contributes to lateral patellar maltracking during normal function, particularly with the knee extended. In vitro simulation and computational simulation studies also indicate that trochlear dysplasia compromises patellar stability in response to a direct lateral force applied to the patella. In vitro simulation indicates that trochlear dysplasia does not necessarily increase the pressure applied to patellofemoral cartilage during stable functional activities. In vitro and computational simulation studies have indicated that groove deepening trochleoplasty reduces lateral patellar maltracking and improves stability to reduce the risk of lateral patellar dislocation. Altering the shape of the trochlear groove without a corresponding change to the patella can increase pressure applied to patellofemoral cartilage, however.