THE EPIDEMIOLOGY OF BILATERAL SLIPPED CAPITAL FEMORAL EPIPHYSIS - A STUDY OF CHILDREN IN MICHIGAN

The records of 224 children who had a slipped capital femoral epiphysi s and who had no underlying metabolic or endocrine disorder were studi ed retrospectively to investigate the epidemiology of bilateral slippe d capital femoral epiphysis. Eighty-two (37 per cent) of the 224 child ren (fifty-one boys and thirty-one girls) had a bilateral slip. Sixty- four of these children were black and eighteen were white. The age at the time of the diagnosis of the first slip was 13 +/- 1.7 years (mean and standard deviation), the duration of the symptoms was 5 +/- 5.0 m onths, and the angle of the slip was 26 +/- 16 degrees. Obese children were younger at the time of the diagnosis of the first slip (12 +/- 1 .6 compared with 13 +/- 1.6 years for the children who were not obese, p = 0.001). The diagnosis of a slipped capital femoral epiphysis was made simultaneously in both hips in forty-one children and sequentiall y in forty-one children. Compared with the children in whom both hips were diagnosed simultaneously, the children in whom the hips were diag nosed sequentially had had a shorter duration of the symptoms before t he diagnosis of the first slip (3 +/- 2.4 compared with 7 +/- 5.9 mont hs, p = 0.0003), were younger at the time of the diagnosis of the firs t slip (12 +/- 1.9 compared with 13 +/- 1.2 years, p = 0.001), and ten ded to be more obese (p +/- 0.025). In 88 per cent of the patients who had sequential slips, the second slip was diagnosed within eighteen m onths after the diagnosis of the first slip. The children who had a un ilateral slip and in whom a slip of the contralateral hip developed su bsequently were younger at the time of the diagnosis of the first slip than those in whom a contralateral slip did not develop (12 +/- 1.9 c ompared with 13 +/- 1.6 years, p = 0.002). We recommend frequent follo w-up examinations for the first two years after the diagnosis of a uni lateral slip, especially if the patient is a girl who is twelve years old or less or a boy who is fourteen years old or less. In order to pr event a delay in the diagnosis of a second slip, follow-up should cont inue until there is definite radiographic evidence of physeal closure in both hips.