ISOLATED MEDIAL PATELLOFEMORAL LIGAMENT RECONSTRUCTION WITH SEMITENDINOSUS TENDON ALLOGRAFT

Background: Medial patellofemoral ligament (MPFL) reconstruction is recommended to surgically stabilize the patella against excessive lateral patellar translation. It is currently the cornerstone of treatment for recurrent lateral patellar instability. The MPFL is often disrupted during acute patellar dislocations but may also be attenuated in the setting of recurrent lateral instability. Numerous techniques have been developed with the primary goal of restoring the static function of the MPFL in resisting lateral translation of the patella during early flexion of the knee. There are now numerous options for the surgical technique, fixation devices, and graft choice, with equal clinical results as long as key surgical principles are maintained(1). This article provides a step-by-step description of our preferred technique as well as offering technical pearls and a review of patient outcomes. Description: The MPFL is reconstructed anatomically using a hamstring allograft or autograft with an ideal width of 4 to 5 mm. The graft is secured to the femur with an interference screw at its anatomic insertion point, which can be defined by radiographic or anatomic landmarks, is passed through the soft tissues between the capsule and the medial retinaculum/vastus medialis oblique muscles, and is secured to the superomedial patellar border. Alternatives: Nonoperative treatment of lateral patellar dislocations is associated with recurrent dislocation rates of 35% to 50%; surgical treatment for recurrent dislocations has afforded improved patient outcomes(2,3). In general, there are 3 surgical options to restore the function of the MPFL. Historically, acute repair was thought to offer the MFPL a chance to "heal" and resume its function; however, the literature has failed to support this as a reliable option in the setting of lateral patellar instability(4). Similarly, delayed tightening or imbrication of the MPFL in the setting of chronic laxity has not demonstrated worthwhile clinical results(5). MPFL reconstruction with a graft, as described here, has provided the most consistent outcomes. Rationale: Isolated reconstruction of the MPFL is indicated for patients with a history consistent with recurrent lateral patellar instability and a physical examination demonstrating excessive lateral patellar translation. Patients with high-grade trochlear dysplasia and patella alta may be better treated with concomitant osseous procedures such as trochleoplasty or tibial tubercle osteotomy.