Understanding When Kids Need Hip Surgery After Selective Dorsal Rhizotomy for Cerebral Palsy

Research study background

Children with cerebral palsy frequently develop neuromuscular hip dysplasia, which happens when muscle spasticity and imbalance pull the hip out of proper alignment. Care teams use an established treatment, selective dorsal rhizotomy (SDR), to reduce spasticity. But researchers don’t yet understand what impact SDR might have on the need for future hip surgery. After hearing this question from many patients, the orthopedics team at Children’s Hospital Colorado set out to find answers in the data.

In the team’s retrospective cohort study of 68 children with SDR, investigators sought to identify clinical and radiographic factors associated with subsequent hip surgery. The team used an approach called survivor analysis to characterize each patient's baseline prior to SDR surgery. This allowed them to determine which factors were associated with an additional hip surgery later in life and on what timeline. Approximately 24% of patients required hip surgery after SDR, typically about three years after their SDR procedure.

Among all the variables, the preoperative acetabular index emerged as the strongest independent predictor of future hip surgery. Although both acetabular index and migration index were associated with surgical risk, only acetabular index remained significant after adjusting for age, sex and other clinical factors. Any increase in acetabular index was associated with a significantly higher chance of hip surgery. Children with an acetabular index of 23 degrees or greater experienced earlier and more frequent hip surgery than those with lower values prior to SDR.

Relevance to practice

Overall, the findings suggest that families and care teams should not consider SDR a way to prevent future hip surgery. Instead, X-ray measurements, including acetabular index, may help identify children who are at higher risk and need more frequent orthopedic follow-up after SDR. Incorporating acetabular index into preoperative counseling can better inform care teams and families about long-term orthopedic risks and postoperative surveillance needs.