Normal femoral head development in adolescence and the cam morphology

Abstract

Purpose: We set out to observe the change in morphology of the femoral head and head/neck junction during skeletal maturation in males and females and to assess the incidence of cam development in adolescents, using a number of objective measurement parameters. Methods and materials: A retrospective review of our institutional imaging database was undertaken. Anteroposterior pelvic radiographs were reviewed at ages to coincide with pubertal development. After applying inclusion and exclusion criteria, 109 male patients and 66 female patient images were available for analysis. A number of objective measures were made of the femoral head/neck junction including gamma angle (a measure of flattening of the femoral head/neck junction), epiphyseal extension along the femoral neck and femoral head/ neck offset amongst others. Results: The gamma angle increased with age and was statistically significant in males (p = 0.001). The difference between the lateral to middle (L to M) ratio and the middle to medial (M to M) ratio for epiphyseal extension increased with age for both males (p = 0.001) and females (p < 0.001) and was statistically significant. The ratio of lateral to medial head/neck offset significantly decreased with increasing age in females (p < 0.05). Conclusion: An increasing incidence of cam morphology with skeletal maturation in adolescence was observed, more often in males and appears at least in part due to lateral epiphyseal extension along the femoral neck. The high incidence of the cam morphology in an otherwise normal cohort of adolescents raises the possibility that the cam morphology can be seen as a normal variant of development.L720612762015-11-05 <br />