Lateral femoral scan: an alternative method for assessing bone mineral density in children with cerebral palsy

Background. Children with cerebral palsy (CP), often non-ambulatory and/or on anticonvulsants, are at increased risk for fractures. Bone mineral density (BMD) measured by the conventional techniques of dual-energy X-ray absorptiometry (DXA) often cannot be reliably or easily measured in these patients. Objective. To find an alternative site to whole body, spine and hip that can be conveniently used to measure BMD in CP patients. Material and methods. Having observed that CP patients prefer to lie on their sides, we explored measuring BMD at the distal femur in the lateral projection. A total of 92 scans were performed without sedation in 34 children and adolescents with CP, aged 4-19 years. Four femoral shaft subregions were created: two trabecular and two cortical. Results. The coefficients of variation (CV%) were generally higher for opposite-side comparisons (n = 12 patients) than for same-side comparisons (n = 16 patients). For intra-and interobserver analyses, CV% were higher for cortical regions than for trabecular regions. Overall, the CV% were similar to those for hip and spine. Conclusion. This peripheral site in the femur should be considered as an alternative for patients with CP when whole-body hip and spine DXA are not practical.