Dynamic Valgus Instability of the Knee due to Chronic Medial Collateral Ligament Laxity as a Cause of Recurrent Patella Dislocation

Recurrent patella dislocation can be caused by bony abnormalities, such as patella alta, increased tibial tubercle lateralization, trochlea dysplasia, excessive femoral neck anteversion and external tibial torsion. It can also be caused by soft tissue abnormalities such as a ruptured medial patellofemoral ligament (MPFL) or a weak vastus medialis obliquus. It has been reported in the literature that acute lateral dislocation of the patella can be associated with proximal injury to the medial collateral ligament (MCL). This article reports the case of a 26-year-old male pro footballer who had recurrent patella dislocation related to previous injury to his MPFL and worsened by dynamic valgus knee instability due to chronic MCL insufficiency.