Predisposing Anatomical Patellofemoral Factors for Subsequent Patellar Dislocation

Primary patellar dislocation is a relatively uncommon knee injury but carries a high risk of recurrence, particularly in young and physically active adolescent individuals. Anatomical features of the patellofemoral joint have been implicated as key contributors to instability. The purpose of this study was to evaluate anatomical risk factors associated with recurrent patellar dislocation following a primary traumatic event, using MRI-based parameters.

Fifty-four patients who sustained a first-time lateral patellar dislocation were included. MRI was used to measure tibial tuberosity-trochlear groove (TT-TG) distance, tibial tuberosity-posterior cruciate ligament (TT-PCL) distance, Insall-Salvati ratio (IS), sulcus angle (SA), patellar tilt angle (PTA), patella length, and patellar tendon length. Trochlear dysplasia was assessed according to the Dejour classification. Recurrence was defined as a subsequent dislocation occurring within three years of the primary injury.

Significant differences were observed in TT-TG distance and patellar tendon length (p < 0.05). Patients with recurrent dislocation had lower TT-TG values and shorter patellar tendon lengths. Other parameters, including PTA, IS, and patella height, did not show statistically significant differences.

Anatomical factors may contribute to the risk of recurrent patellar dislocation. Identifying these variables using imaging may support clinical decision making and guide individualized treatment plans following primary injury.