title: Patellar instability.
abstract: Recurrent patellar instability can result from osseous abnormalities, such as patella alta, a distance of >20 mm between the tibial tubercle and the trochlear groove, and trochlear dysplasia, or it can result from soft-tissue abnormalities, such as a torn medial patellofemoral ligament or a weakened vastus medialis obliquus. Nonoperative treatment includes physical therapy, focusing on strengthening of the gluteal muscles and the vastus medialis obliquus, and patellar taping or bracing. Acute medial-sided repair may be indicated when there is an osteochondral fracture fragment or a retinacular injury. The recent literature does not support the use of an isolated lateral release for the treatment of patellar instability. A patient with recurrent instability, with or without trochlear dysplasia, who has a normal tibial tubercle-trochlear groove distance and a normal patellar height may be a candidate for a reconstruction of the medial patellofemoral ligament with autograft or allograft. Distal realignment procedures are used in patients who have an increased tibial tubercle-trochlear groove distance or patella alta. The degree of anteriorization, distalization, and/or medialization depends on associated arthrosis of the lateral patellar facet and the presence of patella alta. Associated medial or proximal patellar chondrosis is a contraindication to distal realignment because of the potential to overload tissues that have already undergone degeneration.
authors.affiliation: Mount Sinai School of Medicine, 5 East 98th Street, Box 1188, New York, NY 10029, USA. alexis.colvin@gmail.com
authors.forename: Alexis Chiang
authors.initials: AC
authors.lastname: Colvin
authors.forename: Robin V
authors.initials: RV
authors.lastname: West
mesh_terms: D001178:Arthroplasty; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis / Q000209:etiology / Q000601:surgery*; D008023:Ligaments, Articular / Q000601:surgery; D031222:Patellar Dislocation / Q000175:diagnosis / Q000209:etiology / Q000601:surgery*