Challenges in clinical assessment of bone density and quality in children

[Bone mineral density in a population with severe infantile cerebral palsy]

OBJECTIVE

To determine the bone mineral density (BMD) values in children and adolescents with moderate and severe infantile cerebral palsy (ICP) in our catchment area, and compare these values with a healthy population.

MATERIAL AND METHOD

A prognostic study of cases and controls for the assessment of BMD in patients from 2 to 18 years old with infantile cerebral palsy belonging to the Gross Motor Function Classification System (GMFCS) Groups IV and V. The BMD measurements were performed at distal femur level, dividing this region into 3 areas following the forearm protocol.

RESULTS

The BMD for each of the three areas studied results in the final sample of 69 patients were much lower than the reference levels. There was a statistically significant difference (P<.05) between the BMD values in the two sub-groups studied.

DISCUSSION

The greater the involvement, from a neurological point of view, in patients classified as Group V shows a very low BMD compared to patients of similar sex and age. The acquisition of bone capital in patients with ICP does not follow the normal pattern of the healthy population.

A hip analysis protocol for pediatric bone densitometry: the Iowa Bone Development Study

Pediatric proximal femur dual-energy X-ray absorptiometry (DXA) scans present analytic challenges because of the lack of standard points of reference in the growing skeleton. The Iowa Bone Development Study (IBDS) developed a modified pediatric-specific proximal femur analysis protocol using Hologic software. Serial DXA measurements were obtained for 214 children at approximate ages 5, 8, 11, and 13 yr. Standard analysis procedures as described by the manufacturer (Hologic default) were compared with the IBDS protocol. The IBDS protocol yielded lower but more stable results for bone area, bone mineral content (BMC), and bone mineral density for total hip, femoral neck, trochanter, and intertrochanter as a result of more precisely controlling the regions of interest. Linear regression models with body size, age, and gender as predictors were developed to examine variation in measurements. Coefficients of determination (R(2)) with the IBDS protocol were greater for each time point, demonstrating that the modified protocol was better aligned with body size. Similarly, Spearman correlation coefficients between total hip and hip subregions were consistently higher for BMC and bone area with the IBDS protocol with differences more notable among younger children. The IBDS protocol provides a reproducible method for evaluating pediatric proximal femur DXA scans during growth.