Patellar Dislocation in the United States: Role of Sex, Age, Race, and Athletic Participation

Abstract

An estimated 25% of all knee complaints in sports medicine clinics are related to the patellofemoral joint, and patellar instability represents a common complaint among young athletic cohorts. 1 Patellar instability, which includes both subluxation and complete patellofemoral dislocation, com-prises~2 to 3% of all knee injuries. 2 However, the etiology of patellofemoral instability is multifactorial. Proposed risk factors including history of prior patellar dislocation, young age, female gender, family history of patellofemoral instability, aberrant osseous architecture (patella alta, trochlea dysplasia, increased tibial tubercle-trochlear groove distance), soft tissue factors (joint hypermobility, medial patellofemoral ligament disruption, weakened vastus medialis), and limb malalignment. Furthermore the sequelae of patellofemoral instability are well documented, with recurrent dislocation rates between 15 and 50% 3-5 and other long-term complaints Keywords ► patella ► dislocation ► patellofemoral ► instability ► epidemiology

High rate of recurrent patellar dislocation in skeletally immature patients: a long-term population-based study

“…Furthermore, previous studies suggest that peak incidence of patellar instability occurs in adolescent patients between ages 10 to 20 years [3,9,18,27]. Some patients will only experience a single episode of patellar dislocation, but up to 39% may have recurrent patellar instability [14,15].…”

Surgical versus conservative treatment of primary patellar dislocation. A systematic review and meta-analysis

“…Patellar dislocations mainly occur during athletic activity [4], and the most common mechanism of injury is an internal rotation of the femur on a planted foot with a valgus component; however, patellar dislocation can also occur after low-energy trauma in people with predisposing factors [5].…”

Medial Patellofemoral Ligament Reconstruction in Adolescents Affected by Patellar Instability

“…It often occurs in young patients during sporting activities, such as basketball, soccer, and football [4], with associated predisposing factors, these being joint hyperlaxity, lower limb malalignment, external tibial torsion and increased Q-angles [1,16]. The traumatic mechanism consists of an internal rotation of the leg relative to a fixed foot, often including simultaneous quadriceps contraction, and more rarely consists of a direct trauma to the medial patellar surface [17].…”

“…The rates of acute, traumatic patellar dislocation peaks among adolescents 15 to 19 years old, with an incidence of 11.19 people per 100,000 years [4]. Recognized predisposing factors of patellar instability are genu valgum, patella alta, ligament laxity, contracture of the lateral patellar soft tissues, hypoplasia of the lateral femoral condyle, a laterally located tibial tubercle, vastus medialis insufficiency, and abnormal attachment of the iliotibial tract.…”