Radiological assessment of the effects of splinting on early hip development: results from a randomised controlled trial of abduction splinting vs sonographic surveillance.

Whilst delayed treatment of fully dislocated hips diagnosed at birth prejudices final outcome, splinting clinically dislocatable hips is controversial as the majority stabilise spontaneously. Early stabilisation may not ensure normal development but even early splinting carries a small risk of avascular necrosis. We report radiological data from 76 newborns with dislocatable hips that were randomised either to immediate splinting or to sonographic surveillance which examines the influence of early splinting on hip development. Epiphyseal maturation (EM), iliac indentation (II) and acetabular angle (AA) were assessed radiographically at 6 months, blind to the treatment group; hips with normal sonograms at birth had greater EM and II and smaller AA. Whilst clinically unstable Graf type 1 and 2A hips were radiologically similar at 6 months, those splinted showed poorer EM and II compared with non-splinted hips. There were no cases of avascular necrosis. Abduction splinting may displace the femoral capital epiphysis medially resulting in poorer iliac indentation. The smaller epiphysis in splinted infants may be secondary to altered blood supply due to increased pressure between the femoral head and acetabulum and increased tension of the adductor muscles in the thigh. These differences were less marked by 1 year. Whether they have any long-term significance requires further study.