MPFL Injury

The Medial Patellofemoral Ligament (MPFL) is an hour-glass-shaped ligament made of bands of retinacular tissue. The MPFL plays a significant role in the stabilization of the medial aspect of the patella. Especially during the early stages of knee flexion, the MPFL is a critical component in patellar tracking and stability within the trochlear groove. 

Function
The main function of the medial patellofemoral ligament is to provide restraint to the patella during early knee flexion (0-30 degrees). It acts in maintaining appropriate patellar tracking within the trochlear groove while providing 50-60% of the restraining force against lateral displacement.

Clinical relevance
During acute lateral patellar dislocations (LPD), the MPFL is ruptured >90% of the time with almost 100% rupture occurring in repeat dislocations.[3] Lateral dislocations most often occur when the foot is planted and an internal rotational force is applied to a flexed, valgus knee joint[2]. MPFL reconstruction surgery is often performed in patients with patellofemoral instability who have suffered recurrent lateral patellar dislocations. Surgical repair of the MPFL restores the medial patellar stability.

Assessment
Magnetic Resonance Imaging (MRI) provides the most accurate assessment of MPFL soft tissue integrity.[4].

Treatment
Conservative treatment, especially after the first lateral patellar dislocation, has been regarded as the most appropriate course of treatment. Rehabilitation with Physical Therapy and bracing is the prescribed treatment for lateral patellar dislocation. Surgical intervention of the MPFL is performed only when conservative treatment fails or the patient presents with recurring dislocations.