title: Patellar instability.
abstract: Patella instability can cause significant pain and functional limitations. Several factors can predispose to patella instability, such as ligamentous laxity, increased anterior TT-TG distance, patella alta, and trochlear dysplasia. Acquired factors include MPFL injury or abnormal quadriceps function. In many cases, first-time dislocation can successfully be managed with physical therapy and other nonoperative management; however, more than one dislocation significantly increases the chance of recurrence. Surgical management can improve stability, but should be tailored to the injuries and anatomic risk factors for recurrent dislocation. Isolated lateral release is not supported by current literature and increases the risk of iatrogenic medial instability. Medial repair is usually reserved for patients with largely normal anatomy. MPFL reconstruction can successfully stabilize patients with medial soft tissue injury but is a technically demanding procedure with a high complication rate and risks of pain and arthrosis. Tibial tubercle osteotomy can address bony malalignment and also unload certain articular cartilage lesions while improving stability. Trochleoplasty may be indicated in individuals with a severely dysplastic trochlea that cannot otherwise be stabilized. A combination of procedures may be necessary to fully address the multiple factors involved in causing pain, loss of function, and risk of recurrence in patients with patellar instability.
authors.affiliation: Orthopaedic Surgery, NorthShore University HealthSystem, 2650 Ridge Avenue, Walgreen's 2505, Evanston, IL, USA; Department of Orthopaedic Surgery and Rehabilitation Medicine, University of Chicago Medicine & Biological Sciences, 5841 S. Maryland Avenue, Rm. P207, MC 3079, Chicago, IL 60637, USA. Electronic address: kohj1@hotmail.com.
authors.forename: Jason L
authors.initials: JL
authors.lastname: Koh
authors.affiliation: Department of Orthopaedic Surgery and Rehabilitation Medicine, University of Chicago Medicine & Biological Sciences, 5841 S. Maryland Avenue, Rm. P207, MC 3079, Chicago, IL 60637, USA.
authors.forename: Cory
authors.initials: C
authors.lastname: Stewart
mesh_terms: D006801:Humans; D007593:Joint Instability / Q000175:diagnosis* / Q000628:therapy*; D031222:Patellar Dislocation / Q000175:diagnosis / Q000628:therapy; D057071:Patellofemoral Joint / Q000033:anatomy & histology
keywords: Dislocation; Injury; Instability; Knee; Medial patellofemoral ligament; Patella