Correlation of radiographic changes with disease severity and demographic variables in children with stable slipped capital femoral epiphysis

Abstract

The duration of symptoms in children with stable slipped capital femoral epiphysis (SCFE) varies widely, and radiographic metaphyseal changes develop at some point. It was the purpose of this study to investigate if metaphyseal changes correlate with symptom duration and other demographic parameters. A retrospective review of 97 children with idiopathic stable SCFE between 1998 and 2005 was performed. The child's sex, age, weight, height, body mass index (BMI) at diagnosis, and symptom duration were recorded. Anteroposterior and frog-lateral radiographs were reviewed to measure SCFE severity, the occurrence of adaptive changes, and the status of Klein line. Standard bivariate and logistic regression statistical analyses were used. A P < 0.05 was considered statistically significant. The average age was 12.4 +/- 1.7 years, symptom duration, 5.7 +/- 5.9 months; BMI, 28.3 +/- 4.3 kg/m; and SCFE angle, 28 degrees +/- 18 degrees. There was a correlation between SCFE severity and symptom duration (P = 0.002) but significant variability (r = 0.09). Metaphyseal changes were seen superiorly in 76%, inferiorly in 56%, anteriorly in 80%, and posteriorly in 84%. Symptom duration was not predictive of an abnormal Klein line. Those with more metaphyseal changer were older, had a longer duration of symptoms, had higher BMI, and had more severe SCFEs. Although SCFE severity generally increased with longer symptoms, some had prolonged symptoms with a mild SCFE, whereas others had short symptoms with a severe SCFE; perhaps the SCFE remains silent for varying periods of time before symptoms occur. Those children with more metaphyseal changes had higher BMIs; perhaps the larger body mass per unit of height translates into more bony adaptation following Wolf law.