Background: Although it has been postulated that injury to the proximal femoral physis results in the formation of a cam lesion, a clear causal association has not been established.
Purpose: The purpose of this study was to investigate the relationship between the physis and the cam lesion. Our hypotheses were that (1) the location of the cam lesion would coincide with the growth plate and (2) the distance between the cam lesion and the physis would vary as a function of skeletal maturity.
Methods: A retrospective review of the charts and magnetic resonance images of adolescent patients with femoroacetabular impingement (FAI) was performed. Data collected included the alpha angle, the distance between the cam lesion and physis, and physeal status. Linear mixed models were used to describe the association between the distance to the cam lesion and physeal status.
Results: Twenty-four hips in 17 patients were included. The average alpha angles were 50.7, 63.2, 64.4, and 63.9 degrees for the anterior, anterosuperior, superoanterior, and superior radial magnetic resonance imaging sections. The average distance from the cam lesion to the physis was 0.07 cm. There was a significant association between physeal status and the distance of the cam lesion to the physis.
Conclusions: The location of the cam lesion occurs at the level of the physis. In skeletally mature adolescents, the cam lesion is located further from the physis than it is in patients whose growth plates remain widely open. This suggests a possible causal relationship between physeal injury and the development of the cam deformity in patients with femoroacetabular impingement.
Level of Evidence: Level IV—retrospective case series.