Racial differences in late-onset Blount disease

Walter Klyce; Daniel Badin; Jigar S Gandhi; R Jay Lee; B David Horn; Erin Honcharuk

doi:10.1177/18632521221091501

Racial differences in late-onset Blount disease

J Child Orthop. 2022 Jun;16(3):161-166. doi: 10.1177/18632521221091501. Epub 2022 May 10.

Authors

Walter Klyce^{1

2}, Daniel Badin², Jigar S Gandhi^{3

4}, R Jay Lee², B David Horn⁴, Erin Honcharuk⁵

Affiliations

¹ Department of Orthopaedic Surgery, Case Western Reserve University, Cleveland, OH, USA.
² Division of Pediatric Orthopaedics, Johns Hopkins Children's Center, The Johns Hopkins University, Baltimore, MD, USA.
³ Department of Orthopaedic Surgery, Cooper University Hospital, Camden, NJ, USA.
⁴ Division of Orthopaedics, Children's Hospital of Philadelphia, Philadelphia, PA, USA.
⁵ Department of Orthopaedic Surgery, The Johns Hopkins University, Baltimore, MD, USA.

Abstract

Purpose: Blount disease is most common among obese Black children. The reason for Blount's racial predisposition is unclear. Given that obesity is a risk factor for Blount disease and the known associations between race, obesity, and socioeconomic status in the United States, we hypothesized that socioeconomic status and severity of obesity differ between Black and non-Black children with late-onset Blount disease. We additionally examined differences in treatment types between Black and non-Black children.

Methods: One hundred twenty-five patients from two institutions were included. Age at presentation, age of onset, body mass index, race, sex, and treatment type were recorded. These variables were compared between Black and non-Black children. Insurance type and estimated household income were used as markers of socioeconomic status.

Results: Of the 125 patients with late-onset Blount disease, body mass index percentiles were higher for Black patients (96th ± 12th percentile) than non-Black patients (89th ± 22nd percentile) (p = 0.04). Black patients also had lower estimated incomes (US$48,000 ± US$23,000 vs US$62,000 ± US$30,000) (p = 0.01) and much higher rates of Medicaid enrollment (69% vs 24%) (p < 0.01) than did non-Black patients. Regarding treatment types, osteotomy was more common among Black patients (60%) than non-Black patients (38%) (p = 0.033).

Conclusion: The race-related associations we found between obesity and socioeconomic status suggest that non-genetic factors may contribute to observed racial differences in the prevalence of Blount disease.

Level of evidence: level III.

Keywords: Blount disease; obesity; race; socioeconomic status; treatment.