Osteopenic features of the hip joint in patients with cerebral palsy: a hospital-based study

Aim: We aimed to evaluate the bone mineral density of the hip joint in patients with cerebral palsy (CP). Method: Patients with CP younger than 18 years who underwent three-dimensional hip examination by computed tomography were analysed. Bone attenuation of the acetabulum and femur was measured as Hounsfield units (HU), and was adjusted for affecting factors such as hip instability and Gross Motor Function Classification System (GMFCS). Results: One hundred and twenty-six patients with CP and 86 typically developing participants were included. The average bone attenuation was significantly lower in those with CP than in the comparison group (acetabulum: 70.8HU, 95% confidence interval [95% CI] 59.9–81.8; femur: 82.2HU, 95% CI 70.4–95.8). Compared with GMFCS levels I to III, bone attenuation was significantly lower for GMFCS levels IV (acetabulum: 30.9HU, 95% CI 15.7–46.2; femur: 39.7HU, 95% CI 19.9–59.5) and V (acetabulum: 51.7HU, 95% CI 35.9–67.5; femur: 72.5HU, 95% CI 51.9–93.0). The average bone attenuation decreased when the migration percentage was over 37% (acetabulum: 11.6HU, 95% CI 1.4–24.6; femur: 26.8HU, 95% CI 9.9–43.6). Interpretation: Bone attenuation of the acetabulum and femur was significantly affected both by GMFCS level and by severity of hip instability.