Repair of Medial Patellofemoral Ligament Compared to Conservative Treatment for First Time Patella Dislocation; A Randomized Prospective Trial

Background Historic treatment for first time patella dislocation has been largely conservative. Treatment options include nonoperative treatment and a large variety of operative options. Nonoperative treatment, usually consists of bracing and/or immobilization followed by physical therapy, has been problematic due to a relatively high reported redislocation rate(1). The forces involved in a patella dislocation event can damage the articular cartilage of the patella femoral joint. As a result, prevention of recurrent patella dislocation and the associated disability and morbidity has generated significant interest in the orthopedic community.

Historic surgical approaches to recurrent patella dislocation have had mixed results. The isolated "lateral release", has been shown to have a very low success rate(2), while associated complications have been appreciated. Lateral release procedures are now more often performed in conjunction with other proximal or distal realignment procedures(3). More aggressive bone realignment procedures such as tibial tubercle transfers have the disadvantage of reported poor long term functional recoveries and low "return to sport" rates(4,5).

There has been increasing interest in ligament reconstruction for patella dislocation. The ligament of interest is the medial patella-femoral ligament (MPFL), which is essentially a thickened band of the medial capsule of the knee. The MPFL has been established as the primary constraint to patella dislocation. This ligament extends from a point just anterior to the attachment of the medial collateral ligament to the medial aspect of the patella, and is routinely disrupted with a patella dislocation event. The goals of reconstruction procedures are to replace and/or augment this band of tissue. While many reports of the results of MPFL reconstruction have been good to excellent, there are significant associated risks of complication, prolonged recovery, and associated graft costs or autograft harvest morbidity.

An alternative approach to MPFL functional restoration, and the subject of this study proposal, is a direct repair of the MPFL. Variations of this approach have been previously studied. A basic understanding of established injury patterns to the MPFL is requisite to evaluating the limitations to these studies.

Studies evaluating MPFL injury by MRI have shown that acute patella dislocations have a very high incidence of associated MPFL injury. The location of the lesion in the ligament can be described in one of four ways: 1) at the patellar attachment, 2) at the femoral attachment, 3) intrasubstance portion of the ligament, or 4) a combined injury pattern. Several studies have demonstrated varying percent distributions of injury(6,7), but it is clear that all patterns exist. This conclusion is consistent with the author's experience is treating these injuries.