The Role of Physical Examination in Assessing Hip Migration in Children with Cerebral Palsy

Background: Hip migration is a common comorbidity in children with cerebral palsy (CP) and can progress to complete hip dislocation, resulting in a reduced quality of life. Structured surveillance programs designed to prevent complete hip dislocation have demonstrated success regarding the early identification of hip migration. The objectives of this study are to determine whether there is a correlation between hip abduction in flexion (AIF) and migration percentage (MP) and to determine if there are clear cutoff values for hip abduction in flexion that are associated with progressive hip migration. Methods: This retrospective study evaluated children at our neuromuscular clinic between 2018 and 2022. We included children diagnosed with spastic CP for whom hip radiographs and concurrent physical examinations were available. The outcomes were assessed using AIF as a measure of range of motion and migration percentage according to Reimers. Results: In total, 83 patients were included, with a mean MP of 30.7% and a median AIF of 40 degrees. Mixed-effects modeling revealed a significant correlation between MP and AIF (β = -0.51, p < 0.001). Using generalized linear mixed-effects models and ROC analysis, we established a cutoff value of 40 degrees for AIF in predicting MP above 30%, with a sensitivity of 94.5% and a specificity of 80%. Conclusions: A negative correlation between AIF and MP was found, indicating that as AIF decreases, MP increases. Furthermore, a distinct cutoff value of 40° for AIF in progressive hip migration was found, which can guide timely referrals and early imaging.