Treatment of Habitual Patellar Dislocation in an Adult by Isolated Medial Patellofemoral Ligament Reconstruction

Habitual patellar dislocations are rare in adults. Treatment is difficult, and often associated with significant morbidity. A 30-year-old man, construction worker, presented a habitual patellofemoral dislocation which was caused by direct trauma to the knee as a child. Clinical examination showed a 3？cm leg-length discrepancy with no rotational deformities. The patient had a limp and loss of function; the patella was dislocated laterally and had locked at 20° of flexion with a range of motion of 0°/0°/30°. Open surgery was performed associating lateral retinacular release, reconstruction of the medial patellofemoral ligament with an ipsilateral gracilis tendon graft. The postoperative course was simple with no complications. Four months after surgery the patient has begun working normally. At the final 50-month clinical follow-up, knee range of motion was 0°/0°/130°, and functional results were excellent on clinical assessment scores of Kujala, Lysholm, and subjective IKDC. MPFL reconstruction alone seems effective in habitual posttraumatic patellar dislocation in adults without any associated bone anomalies. 1. Introduction The origin of recurrent patellar instability is usually posttraumatic. Dislocation results in irreversible injuries due to lateral translation of the patella [1, 2]. Hawkins et al. [3] reported 40% rates of patellofemoral pain and 70% rates of instability after dislocation. Several factors predisposing to patellar instability have been described such as trochlear dysplasia or a patella alta [4]. Recently several studies have shown that the medial patellofemoral ligament (MPFL) reconstruction in the treatment of patellar instability in adults had a high success rate [5] but with a complication rate of 26% [6]. Few cases of habitual dislocations have been reported [7]. 2. Case Presentation A 30-year-old man consulted for limping. In the past three years, the patient had been having trouble walking, could not squat down, or go up and down stairs. The patient’s history included a knee injury at the age of 5 in a road accident. He did remember neither precise diagnosis nor functional or surgical previous treatment. There were no scars on the knee. The patient was 1.76？m tall and weighed 68？kg with varus knee morphology and no leg-length discrepancy. Placing weight on one foot resulted in lateral patellar dislocation, and squatting was impossible. The patella was mobile, but systematically dislocated laterally at 30° of flexion (Figure 1). Figure 1: Preoperative assessment: the patella is in place in extension and dislocated in flexion.