Bone Mineral Density In Children With Myelomeningocele
from Practice Update, Fall 2006
Osteoporosis is not just a disease of post-menopausal women. Children with spina bifida have up to a 30 percent incidence of fractures during childhood. Researchers at The Children’s Hospital have documented bone mineral density (BMD) in children with myelomeningocele using Dual mEnergy X-ray Absorptiometry (DEXA) and identified variables that contribute to the presence of osteoporosis including nutritional status, neurological level, and ambulatory status. Twenty-four children with a history of spina bifida, ages 4-18 years were enrolled the study. Participants had varied levels of neurological and mobility impairments.
Bone mineral density measurements of the femoral neck and total body using DEXA were obtained. Assessment of dietary calcium was obtained using a food frequency questionnaire. Serum and urine markers of bone metabolism determined whether an active process of formation or resorption was occurring.
Results of this study were not surprising to the researchers given their clinical experience. The mean femoral neck z-score (21/24 participants) was -2.41 with a standard deviation of 2.05 and a p value of <0.001 representing a significant difference between participants and controls. The mean z-score at the femoral neck demonstrated a clear trend toward lower z-scores in the children with a higher level of lesions (thoracic/high lumbar -3.54, mid-lumbar - 2.86, and lumbo-sacral -1.50.) There was a significant difference between ambulatory status and femoral neck z-scores, with lower z-scores in children who were wheelchair dependent. Wheelchair dependent subjects had a mean z-score of -3.60, partial ambulators -2.82, and independent ambulators -1.25 with an overall p-value of 0.03. Of children completing the food-frequency questionnaire, 95 percent (17/18) met their recommended daily intake of calcium. Specific markers of bone metabolism were elevated representing an active process of both formation and resorption in the majority of subjects.
The study demonstrates that osteoporosis is a major complication in children with spina bifida. It establishes the significant relationship between low bone mineral density in children who are wheelchair dependent and a strong trend in those that have higher neurological levels. A treatment regimen has not been universally established for this group of children. However, it is recommended that children with spina bifida be given supplemental calcium and vitamin D despite presumed adequate dietary intake. In addition, for those children who have a history of fractures, use of a bisphosphonates medication may be considered. Non-pharmacological options may include increasing active weight bearing activities. There is currently no strong evidence that passive weight bearing in a standing device will improve bone mineral density.
For more information about this bone density study, contact Susan Apkon, MD or Laura Fenton, MD, at The Children’s Hospital, 720-777-1234.
