O3274: Is There an Association between Abnormal Patellofemoral Morphology and Patellar and Trochlear Osteochondritis Dissecans in Pediatric Patients?

Background: The etiology of patellofemoral osteochondritis dissecans (OCD) is not clear. Biomechanical factors, such as abnormal patellofemoral morphology seen in patients with patellofemoral instability (PFI), such as tibial tubercle-trochlear groove distance (TT-TG) and sulcus angle, have been associated with patellar OCD. These factors, and the microtrauma they potentially introduce to the patella and trochlea, may contribute to the development of OCD of the patella and trochlea. The purpose of this study was to determine whether anatomic risk factors associated with patellofemoral instability are also present in patients with patellar and trochlear OCD.

Methods: This was a retrospective, case-control study comparing three groups of pediatric (≤19 years of age at time of imaging) patients: (1) those with OCD of the patella or trochlea and no history of PFI; (2) those with recurrent (≥2) patellofemoral instability events with no evidence of OCD; and (3) those with normal knee MRIs to serve as controls. Patients with prior surgery to the imaged knee were excluded. Only one knee per patient was included; in cases where patients had bilateral pathology, one knee was randomly chosen. Patients were matched by age, sex, and body mass index (BMI) using propensity-scoring. Measurements of patellar height, position, translocation, and trochlear dysplasia were performed on magnetic resonance imaging (MRI) obtained prior to any surgical intervention. Measurements from patients with patellar/trochlear OCD were compared to those of patients with PFI and to healthy controls. Statistical analysis was performed in IBM SPSS Statistics v29.

Results: 70 patients in each group (210 patients total, mean age at time of imaging 14.6 ± 2.4 years, 106 [50%] female) met inclusion criteria. Patients from the PFI group were older (p < 0.001) and of higher BMI (p=0.02) than those in the OCD and control groups; there were no significant differences in age and BMI between the control and OCD group. Measures of patellar and trochlear dysplasia were not significantly different between controls and the OCD group, except for Caton-Deschamps index (p=0.02). All measures of patellar and trochlear morphology differed significantly between OCD and PFI groups, and control and PFI groups.

Conclusion: Morphologic characteristics of patellofemoral instability do not appear to be associated with OCD lesions of the patella or trochlea. Rather, patients with OCD lesions have knee anatomy that is more similar to that of healthy controls, with the difference in CDI likely not being of clinical significance. Further research is needed to identify risk factors associated with the development of patellar and trochlear OCD.