Evaluation of bone density in children with slipped capital femoral epiphysis

Abstract

Slipped capital femoral epiphysis (SCFE) is a condition seen during the preadolescent growth spurt, often in obese children and in children with endocrine disorders. Given that endocrine factors also play a role in bone density, a link between low bone mineral density (BMD) and SCFE was proposed. Dual energy X-ray absorptiometry (DXA) scanning of the spine and hips was performed on 12 children with SCFE and on 5 overweight children without this hip disorder. All scans were performed by the same technician using a Hologic Delphi W densitometer and were interpreted by a pediatric orthopedic surgeon certified in clinical densitometry. Z-scores were obtained using a pediatric database. Mean and standard deviation of the Z-scores were calculated, and paired t tests were used to assess differences between these subjects and the expected norm. The SCFE patients' Z-scores at each of the skeletal sites assessed (spine, femoral neck, and total hip) were greater than the mean by an average of 1 standard deviation. The control subjects' BMD was also greater than the mean. The P values were less then 0.05. These results suggest that children with SCFE do not have low BMD, but show bone density significantly greater then expected for age and sex. Although BMD is endocrinologically driven and endocrinologic abnormalities are implicated in SCFE, there appears to be no correlation between low BMD and SCFE.