Patellofemoral Instability

Abstract

Recurrent patellofemoral instability is a common cause of knee pain and functional disability in adolescent and young adult patients, resulting in loss of time from work and sports. There are numerous factors that contribute to recurrent patellofemoral instability; these factors include tear of the medial patellofemoral ligament (MPFL), weakening or hypoplasia of the vastus medialis obliquus (VMO), trochlear dysplasia, increased tibial tuberosity-trochlear groove (TT-TG) distance (>20 mm), valgus malalignment, increased Q angle, malrotation secondary to internal femoral or external tibial torsion, patella alta, and generalized ligamentous laxity. A detailed history and a thorough physical examination are crucial to clinch an early, accurate diagnosis. Imaging studies play an important role to confirm the clinical diagnosis and also help to identify concomitant intra-articular pathologies. Initially, nonoperative management (including the use of physical therapy, patellar taping or brace) is offered to patients with acute, first-time patellar dislocations and most patients respond well to this mode of treatment. Surgical treatment is indicated for patients who have post-trauma osteochondral fracture or loose body; predisposing anatomical risk factors; recurrent, symptomatic instability; and who have failed an adequate trial of nonoperative management. Surgical treatments include MPFL reconstruction, proximal or distal realignment procedures, and trochleoplasty. Lateral release is often performed in combination with other procedures and seldom performed as an isolated procedure. An individualized case-by-case approach is recommended based on the underlying anatomical risk factors and radiographic abnormality.