Effects of Standing on Non-Ambulatory Children With Neuromuscular Conditions

Children with neuromuscular disabilities and limited ambulation are at significant risk for decreased bone mineral density (BMD) and increased incidence of fracture. This is caused, in part, by low levels of load experienced by the skeleton due to a child's functional limitations. Low BMD has been shown to be predictive of fracture, and in fact, fractures usually occur without significant trauma in children with neuromuscular conditions such as cerebral palsy, spinal muscular atrophy, or other muscular dystrophies. The discomfort and distress from fractures in this population are considerable, and the associated costs to the family and healthcare system are substantial. Numerous interventions have been devoted to improving BMD in these children. Stationary assisted standing devices are widely used and represent the standard-of-care. However, evidence supporting this approach is limited due to inadequate study designs with insufficient numbers of patients.

Various modifications are added to assisted-standing devices to allow children with neuromuscular impairments to achieve standing postures. These customizations lead to load-sharing with the standing device, and consequently, a decrease in the amount of load passing through the lower extremities. Previous investigators developed custom-made load-measuring sensors to quantify the amount of load borne by the lower extremities while in passive standers, and found that the actual load varied from 23-102% of the child's body weight. These load-measuring sensors were specifically developed for restricted laboratory testing, rather than recording the load magnitude and duration of standing in any brand of standing device during daily use at home, school or therapy.

We previously developed load-sensing platforms that accurately measure loads experienced by the lower extremities of children with cerebral palsy in passive standers. These platforms can be incorporated into any stander design, are able to be used on a routine basis at a child's home, school or therapy, and are able to record the duration of weight-bearing to monitor compliance.

This study will use these load-sensing platforms in patients with neuromuscular conditions. Successful completion of this pilot study will assist in the development of a future multicenter clinical trial to definitively determine relationships, if any, between passive standing and measures of BMD, fracture incidence, pulmonary function, and health-related quality-of-life measures in children with a variety of neuromuscular disabilities (e.g., spinal muscular atrophy, cerebral palsy, muscular dystrophy, spina bifida, Rett syndrome).