Increased BMI Affects Femoral Morphology in Adolescents
Long-term population-based research has documented associations between high BMI and decreased longevity and increased risk of developing diabetes and cardiac complications. Musculoskeletally speaking, the risk of developing osteoarthritis of the knee has been strongly associated with elevated BMI, although the impact of high BMI on the development of hip osteoarthritis has been less clearly defined.
To detail the impact of increased BMI on the developing hip, in the January 3, 2018 issue of The Journal, Novais et al. painstakingly evaluated 128 pelvic CT images from a group of adolescents presenting with abdominal pain but no prior history of hip pathology. The authors found a significant association between increasing BMI percentiles and femoral head-neck alterations, including:
- Increased alpha angle
- Reduced head-neck offset and epiphyseal extension, and
- More posteriorly tilted epiphyses.
Taken together, these morphological anomalies resemble, in the authors’ words, “a post-slip or mild slipped capital femoral epiphysis [SCFE] deformity.”
While the association between elevated body mass and the risk of SCFE has long been known, the impact of high BMI on the morphology of the “normal” hip had not, until now, been described in detail. It makes intuitive mechanical sense that Novais et al. found no impact of high BMI on acetabular anatomy, but because of the orientation of the proximal femoral growth plate, it does make sense that high BMI affects the growing femoral head-neck junction.
It is my hope that consolidating these data with the abundance of other evidence about the health risks of high BMI in growing children will further coalesce worldwide efforts to lower the intake of sugar and “empty carbs” among growing children, and will further spur investment in programs to increase physical activity among this vulnerable age group.
Marc Swiontkowski, MD