Idiopathic slipped capital femoral epiphysis in Amish children.

BACKGROUND: Of the many studies of slipped capital femoral epiphysis, none have specifically addressed Amish children. The Amish reflect a small gene pool relative to the general white North American population. Additional knowledge of the demographics of this disorder in Amish children may provide genetic insights. The purpose of this study was to review the demographics of slipped capital femoral epiphysis in the Amish population. METHODS: A retrospective review of the cases of twenty-five Amish children with slipped capital femoral epiphysis treated at two institutions was performed. The child's gender, age, weight, height, and body mass index at the time of the diagnosis; duration of symptoms; laterality of the slip; birth weight; family history; and slip severity were recorded. The slip was classified as stable or unstable. Patients who had been included in a previously published multicenter study served as a control group. RESULTS: There were seventeen boys and eight girls with a total of thirty-three slipped capital femoral epiphyses; eight of the slips were bilateral. At the time of the diagnosis, the mean age (and standard deviation) was 13.4 +/- 1.6 years, the mean weight and height were 55.6 +/-12.4 kg and 155.5 +/- 10.2 cm, and the mean body mass index was 23.4 +/- 5.4 kg/m(2). The mean duration of symptoms was 6.6 +/-9.0 months. There were thirty-one stable and two unstable slips with a mean slip angle of 38 degrees +/- 20 degrees . Nine (39%) of twenty-three children for whom the information had been recorded had a positive family history of slipped capital femoral epiphysis, a rate that is higher than the 9% and 14.5% rates reported in two other series (p = 0.002). The Amish children were not as heavy as their non-Amish counterparts (55.6 +/- 12.4 kg compared with 66.4 +/- 17.7 kg, p = 0.0036). CONCLUSIONS: Although the children in this study were moderately heavy, they could not be classified as obese on the basis of weight-for-age or body-mass-index percentiles. The high prevalence of family members with slipped capital femoral epiphysis may reflect either a genetic or environmental component, or an interaction between genetics and environment (for example, work load or common chores requiring particular physical positions) in the Amish population.