The demographics of slipped capital femoral epiphysis. An international multicenter study.
One thousand six hundred thirty children with 1993 slipped capital femoral epiphyses were reviewed; 41.2% were girls and 58.8% were boys. There were 47.5% white, 24.8% black, 16.9% Amerindian, 7.4% Indonesian-Malay, 2.1% Native Australian/Pacific Islands, and 1.3% Indo-Mediterranean children. The diseased hip was unilateral in 77.7% and bilateral in 22.3% of the children, and chronic in 85.5% and acute in 14.5% of the children. Of the unilateral slips, 40.3% involved the right hip and 59.7% the left hip. The child's weight was greater than or equal to the ninetieth percentile in 63.2% of the children. The average age for the girls and boys was 12 and 13.5 years. The age at diagnosis decreased with increasing obesity. The youngest children were the Native Australian/Pacific Island children (11.8 years) and the oldest were the white and Indo-Mediterranean children (13 years). The Indonesian-Malay and Indo-Mediterranean children were the lightest in weight, and the black children the heaviest. The Indo-Mediterranean children had the highest proportion of boys (90.5%), and the Native Australian/Pacific Island children the lowest (50%). The highest percentage of bilaterality was in the Native Australian/Pacific Island children (38.2%), and the lowest in the Amerindian children (16.5%). The relative racial frequency of slipped capital femoral epiphysis compared with the white population was 4.5 for the Polynesian, 2.2 for the black, 1.05 for the Amerindian, 0.5 for the Indonesian-Malay, and 0.1 for the Indo-Mediterranean children. In children with unilateral involvement, the age at presentation was younger for those children in whom bilateral disease later developed (12 versus 12.9 years old). In 82% of the children with sequential bilateral slips, the second slip was diagnosed within 18 months of the first slip.