The multifactorial pathogenesis of slipped capital femoral epiphysis (SCFE) almost certainly involves the acetabulum, but previous studies about that relationship have been inconclusive. In the June 21, 2017 issue of JBJS, Hesper et al. report on a matched-cohort study that used precise measurements gleaned from CT to determine that acetabular retroversion—not acetabular depth or overcoverage of the femoral head—is associated with SCFE.
The authors carefully measured acetabular depth, head coverage, and retroversion in three groups of hips: the affected hips of 36 patients with unilateral SCFE, the unaffected contralateral hips of those same patients, and healthy hips of 36 age- and sex-matched controls. They observed no deep acetabula or acetabular overcoverage in the SCFE-affected hips, but they did find a lower mean value for acetabular version (i.e., retroversion) at the level of the femoral-head center in the SCFE-affected hips, relative to contralateral and control hips. The acetabulum was retroverted cranially in cases of severe SCFE compared with mild and moderate cases.
These findings support the hypothesis that SCFE-affected hips have reduced acetabular version, but the authors note that “additional studies will be necessary to determine whether acetabular retroversion is a primary morphological abnormality associated with the mechanical etiology of SCFE, or if it is an adaptive response to the acetabulum after the slip.” Either way, Hesper et al. conclude that their data “may help with planning treatment for patients with residual pain and limited motion related to femoroacetabular impingement after SCFE.