The characteristics of the whole pelvic morphology in slipped capital femoral epiphysis: A retrospective observational study.

Slipped capital femoral epiphysis (SCFE) is a very common disorder affecting the adolescent hip. The etiology of SCFE is multifactorial and mechanical force associated with the characteristic morphology of the hip is considered one of the causes of SCFE. We investigated the characteristics of whole pelvic morphology including pelvic incidence (PI) in patients with SCFE and compared it with pelvic morphology in healthy children. We retrospectively assessed the whole pelvic morphology of 17 patients with SCFE and 51 healthy children using their pelvic computed tomography data. We measured superior iliac angle, inferior iliac angle, and ischiopubic angle as the parameters of pelvic rotation. Additionally, we measured acetabular anteversion of the superior acetabulum (AVsup) and of the center of the acetabulum (AVcen), and measured anterior acetabular sector angle (AASA), posterior acetabular sector angle, and the superior acetabular sector angle (SASA) as parameters of acetabular coverage and PI. Each measurement was compared between the 2 groups. AASA and SASA of patients with SCFE were significantly greater than that of controls, and AVsup of patients with SCFE was significantly smaller. There were no significant differences in pelvic rotation, PI, or AVcen between the 2 groups. This is the 1st report to evaluate SCFE patients' whole pelvic morphology including PI and pelvic rotation. Our results showed that patients with SCFE have excessive coverage of the anterior and superior acetabulum, and a more retroverted cranial acetabulum as compared with healthy control subjects. Such characteristic pelvic morphology may be involved in the onset of SCFE. To clarify the mechanical forces involved in SCFE onset, further investigations of pelvic morphology and alignment, including the femur and spine, are needed.