Pediatric orthopaedists have long been searching for anatomic, mechanical, and metabolic causes of slipped capital femoral epiphysis (SCFE). Adolescent obesity has been a recognized SCFE risk factor for 50 years. (Interestingly, high BMI is a consistent risk factor in males, but females who experience SCFE are often thin.) Possible racial risk factors have been examined as well, with no clear conclusions.
Because the incidence of SCFE is relatively low (1 in 10,000 children according to this JBJS Clinical Summary) and the risk of bilaterality is high (in the range of 30% to 40%), it seems likely that anatomic risk factors are at play. In the January 2, 2020 issue of The Journal, Novias et al. home in on the 3-D anatomy of the epiphyseal tubercle (a small, round protuberance thought to stabilize the epiphysis) and peripheral “cupping” of the epiphysis in patients with and without SCFE.
They found a smaller epiphyseal tubercle and more extensive epiphyseal cupping in patients with SCFE compared with normal hips. The authors encourage further investigation of the first finding to determine whether smaller tubercles are a consequence of the slip process or an anatomic variant that predisposes the epiphysis to slip.
A major strength of this study is that all measurements were made by a single observer blinded to the diagnosis of SCFE and other potentially confounding clinical and demographic data. Also, the measurement processes used in this study have been previously validated.
Investigation into the anatomic features of this disease should continue, along with development of minimally invasive, safe, and inexpensive ways to screen for possible anatomic risk factors. The most pertinent clinical goals are to continue evolving minimally invasive methods of epiphyseal stabilization to prevent and/or treat SCFE and to more accurately identify hips at risk of SCFE.
Marc Swiontkowski, MD