A worldwide study on the seasonal variation of slipped capital femoral epiphysis

The records of 1630 children (671 girls, 959 boys) with 1993 slipped capital femoral epiphyses were reviewed. These children were from all 6 continents and 33 orthopaedic centers. The month of the slip onset was defined as the month when the patient presented to the physician minus the duration of symptoms as reported by the patient. There was a significant variation in the month of onset for the children from North America and Europe, but not Africa, Asia, Australia/New Zealand, or South America. The peak month of onset was 6.8 +/- 2.6 in North America (late June) and 7.9 +/- 2.4 in Europe (late July). This phenomenon of slips occurring significantly more often in the summer months was only present when the children lived north of the 40 degrees N latitude.