January 14, 2016
2 min read

Low BMD may be caused by poor mobility, hypogonadism in cerebral palsy

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In adults with cerebral palsy, low bone mineral density and fragility fractures are prevalent and often driven by poor mobility and hypogonadism, according to recent findings.

Anne Trinh, a PhD student in the department of endocrinology at Monash Health in Australia, and colleagues evaluated 45 consecutive adult patients with cerebral palsy who underwent imaging with DXA at a single tertiary hospital between 2005 and 2015. The mean age of the patients was 28.3 years, and the patient population was 51% men.

The researchers measured BMD by DXA at the lumbar spine, femoral neck and total body on all participants except for those restricted by prior scoliosis surgery, femoral surgery or problems with positioning. They measured total lean mass and fat mass through whole-body scan. Participants were classified as underweight, normal weight, overweight and obese.

Thirty-eight percent of participants had a history of fragility fracture, and three had incurred multiple fractures. Of the participants with history of fracture, eight experienced fracture during childhood, and all of these fractures involved the lower limb. Femur fractures occurred in five participants, and three participants sustained tibia/fibula fractures during childhood. Fractures were documented in 53% of participants during adulthood, four had vertebral crush fractures, whereas the other adulthood fractures were sustained in the ankle (n = 3), ribs (n = 2) and sacrum (n = 1).

In a univariate analysis, the researchers found that no clinical anthropometric or DXA measures were significantly linked to fracture. In nonambulatory participants, however, the following parameters were found to be associated with fracture: bone mineral content, areal BMD at the spine, femoral neck and total body, and femoral neck z score (P < .05). For each unit decrease in femoral neck z score, there was a 3.2-fold risk for fracture (P = .044).

Univariate analysis revealed an association between ambulatory status and gross motor function classification system and z scores at the lumbar spine, femoral neck and total body (P < .05).

Twenty percent of participants were hypogonadal, and this was correlated with decreased skeletal muscle mass index and decreased lumbar spine BMD. A positive association was seen between lean tissue mass and bone mineral tissue in participants with normal gonadal status but not in those with hypogonadism.

“Adults with cerebral palsy experience prevalent fragility fractures at a young age,” the researchers wrote. “Poor mobility and hypogonadism are important factors contributing to low BMD in this cohort. [Lean tissue mass] has a significant positive association with BMD, but its effect is attenuated by the presence of hypogonadism. Early recognition and treatment of hypogonadism in patients with cerebral palsy may have beneficial effects on musculoskeletal health and warrants further study.” – by Jennifer Byrne

Disclosure: The researchers report no relevant financial disclosures.