CORR Insights®: Guided Growth Improves Coxa Valga and Hip Subluxation in Children with Cerebral Palsy.

The development of hip dysplasia and dislocation is an unwelcome complication for a child with cerebral palsy. It can result in problems with positioning, loss of function, and pain [9]. In individuals with an established dislocation, the options are limited and, for many children, are a matter of palliation rather than correction. Generally, surgical intervention for hip dysplasia is more effective—and may be less invasive—when the condition is detected early. The Swedish national surveillance program has shown that systematic surveillance and timely surgery reduces the incidence of hip dislocation in patients with cerebral palsy [2, 3]. Based on recently published studies [2, 11], more centers are adopting a surveillance program with encouraging results for young patients with cerebral palsy and hip dysplasia. It has been widely believed that the imbalance of forces disturbs the loading on the proximal femoral physis, and according to the Heuter-Volkmann law, results in the horizontal physis and coxa valga as well as the persistence of femoral anteversion [7, 8, 10]. This contributes to eccentric loading at the edge of the acetabulum and the acquired acetabular dysplasia [6]. However, the relationship between femoral deformity and hip subluxation has been challenged [1]. In the past, surgical approaches have focused on addressing the overactive muscles. The more proactive use of tone-reducing interventions such as rhizotomy may affect the natural history of the hip, but currently, there is no clear evidence of a change in incidence of hip pathology. In the current study, Hsieh and colleagues [4] report on their use of guided growth for coxa valga in patients with cerebral palsy. They found that the physis became less horizontal and there was a modest reduction in the head shaft angle of the proximal femur as well as a reduction in the migration percentage. Empirically, one would expect that this technique would work best for hips that have not developed acetabular dysplasia or hip subluxation, and this appears to be borne out by their findings. Those hips that continued to migrate and require further surgery had a straighter head shaft angle, more acetabular dysplasia, and a higher migration percentage. The authors suggest that guided growth may not be suitable for hips that have a migration percentage above 50% [4].