Statistical Models to Assess Leg Muscle Mass in Ambulatory Children With Spastic Cerebral Palsy Using Dual-Energy X-Ray Absorptiometry
Abstract Cerebral palsy (CP) is a movement disorder associated with small and weak muscles. Methods that accurately assess muscle mass in children with CP are scarce. The purpose of this study was to determine whether dual-energy X-ray absorptiometry (DXA) accurately estimates midleg muscle mass in ambulatory children with spastic CP. Ambulatory children with spastic CP and typically developing children 5-11 y were studied (n = 15/group). Fat-free soft tissue mass (FFST) and fat mass at the middle third of the tibia (i.e., midleg) were estimated using DXA. Muscle mass (muscle MRI ) and muscle mass corrected for intramuscular fat (muscle MRIfc ) in the midleg were estimated using magnetic resonance imaging (MRI). Statistical models were created to predict muscle MRI and muscle MRIfc using DXA. Children with CP compared to typically developing children had lower FFST (38%), muscle MRI (40%) and muscle MRIfc (47%) (all p MRIfc to FFST (17%, p MRI (13%) and muscle MRIfc (22%) (both p MRI and 90% of the variance in muscle MRIfc in children with CP (both p MRI and muscle MRIfc (both p > 0.99). We conclude that DXA-based statistical models accurately estimate midleg muscle mass in children with CP when the models are composed using data from children with CP rather than typically developing children.