Association between Patellofemoral Anatomy and Chondral Lesions of the Knee in Patellofemoral Instability.

ABSTRACT

Chondral injury is a serious consequence of patellar dislocation and patellofemoral instability (PFI). There is limited data on the relationship between radiological features such as sulcus angle and patellar height to the presence, location, and severity of chondral lesions. The purpose of this study was to determine the association of anatomical variants in patellofemoral instability with injuries sustained due to patellar dislocation. A cohort of 101 patients who had four or more episodes of dislocation or instability undergoing isolated arthroscopy or arthroscopies at the time of corrective realignment surgery were identified. The prevalence of chondral, ligamentous, and meniscal injuries was determined and correlated to the sulcus angle, tibial tubercle trochlear groove distance, and patellar height on magnetic resonance imaging (MRI) scans. A total of 101 patients was identified. At arthroscopy, the patella demonstrated the highest incidence of chondral injury (68%) followed by the trochlear groove (40%). Lateral meniscal injuries were noted in 6% of patients, medial meniscal injuries in 2%, and anterior cruciate ligament (ACL) injury in 3%. Chondral injuries were graded using the Outerbridge criteria and there was a correlation between more severe chondral injuries and a greater tilt angle (p = 0.05). The occurrence of injury to the lateral meniscus was associated with a higher Insall-Salvati ratio (p = 0.05). More severe chondral injuries are seen in patients with a greater tilt angle.