title: Use of computed tomography to determine the risk of patellar dislocation in 921 patients with patellar instability.
abstract: The purpose of this research was to identify reliable tomographic measurements that can detect patellofemoral abnormality and allow quantification of the risk of patellar dislocation in patients with potential patellar instability. A cross-sectional study in 921 patients with anterior pain or knee instability of at least 6 months' duration was conducted from July 2001 to December 2009. All subjects were clinically evaluated and underwent radiography and computed tomography of their knees. According to their degree of dislocating patellar dysplasia, the subjects were classified into groups for statistical comparison. There was a statistically significant difference in all measurements when the groups were compared, except for external tibial torsion angle. The most sensitive and specific measurements for determining patellar instability were the trochlear groove angle, tibial tubercle-trochlear groove distance, average patellar tilt, and average patellar height. Patients with potential patellar instability, increased tibial tubercle-trochlear groove distance, and patellar height, tilt, and deviation measurements had a greater risk for patellar dislocation. The clinical relevance of this study is to determine measurements that are able to tell us about patellar dislocation risk.
authors.affiliation: Serviço de Pós Graduação em Cirurgia do Joelho e Artroscopia do IOT e Traumasports de Joinville, Joinville, Santa Catarina, Brazil.
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Schueda
authors.affiliation: Departamento de Ortopedia e Traumatologia da Escola Paulista de Medicina, São Paulo, Brazil.
authors.forename: Diego Costa
authors.initials: DC
authors.lastname: Astur
authors.affiliation: Serviço de Cirurgia do Joelho e Artroscopia do IOT e Traumasports de Joinville, Joinville, Santa Catarina, Brazil.
authors.forename: Rodrigo Schueda
authors.initials: RS
authors.lastname: Bier
authors.affiliation: Pontifícea Universidade Católica, Curitiba, Brazil.
authors.forename: Debora Schueda
authors.initials: DS
authors.lastname: Bier
authors.affiliation: Faculdade de Ciencias Médicas da Santa Casa de Misericórdia de São Paulo, São Paulo, Brazil.
authors.forename: Nelson
authors.initials: N
authors.lastname: Astur
authors.affiliation: Departamento de Ortopedia e Traumatologia da Escola Paulista de Medicina, São Paulo, Brazil.
authors.forename: Moisés
authors.initials: M
authors.lastname: Cohen
keywords: knee; patellofemoral instability; patellofemoral syndrome