Seasonal variation of slipped capital femoral epiphysis.

To correlate the season of the year with the prevalence of slipped capital femoral epiphysis, we reviewed the cases of 177 patients who had 243 slips during an eleven-year period. We assessed the month when the patient was seen and the implied time of onset of the slip and found a statistically significant variation for both. The average time of onset was mid-June, with a standard deviation of 2.5 months, and was not significantly different for race, sex, or laterality. We attributed the increased incidence of slipped capital femoral epiphysis during the summer to increased physical activity in that season.