Effects of Standing on Non-Ambulatory Children With Spinal Muscular Atrophy
Condition: Spinal Muscular Dystrophy; Neuromuscular Disability
MeSH terms: Muscular Dystrophies; Muscular Atrophy; Muscular Atrophy, Spinal; Atrophy
Study type: Interventional

Summary: 
      Non-ambulatory children with a neuromuscular disability such as spinal muscular atrophy (SMA)
      are at significant risk for poor bone health as defined by low bone mineral density (BMD) and
      increased propensity to fracture. Poor bone health is thought to be related, at least in
      part, to abnormally low levels of load experienced by the skeleton. A common physical
      approach for increasing bone density is to stimulate the musculoskeletal system by increasing
      the amount and duration of weight-bearing in the lower extremities. For non-ambulatory
      individuals, this takes the form of using an assisted standing device to enable the child to
      spend time in a standing position with some degree of weight placed on the lower limbs. Some
      of these physical interventions demonstrate variable improvement in BMD in children with
      neuromuscular conditions, and some do not. A serious limitation in the previous work in this
      area is a failure to objectively measure the magnitude and duration of the loading
      experienced by the lower extremities. Thus, a lack of change in BMD may be due to the
      extremities experiencing only a fraction of the body weight (due to load-sharing with the
      assistive device) for an inadequate duration of standing time.

      In order to investigate the efficacy of standing treatment for increasing BMD, the
      investigators will develop a simple, portable and inexpensive transducer that will measure
      the magnitude and time course of the load experienced by the lower extremities of individuals
      with SMA who use a stationary assisted standing device. The specific goal of this proposed
      project will be to develop, validate and establish the initial feasibility of such a
      measurement device.
    

Detailed description: 
      Background: Non-ambulatory children with a neuromuscular disability such as spinal muscular
      atrophy (SMA) are at significant risk for poor bone health as defined by low bone mineral
      density (BMD) and increased propensity to fracture. Poor bone health is thought to be
      related, at least in part, to abnormally low levels of load experienced by the skeleton. A
      common physical approach for increasing bone density is to stimulate the musculoskeletal
      system by increasing the amount and duration of weight-bearing in the lower extremities. For
      non-ambulatory individuals, this takes the form of using an assisted standing device to
      enable the child to spend time in a standing position with some degree of weight placed on
      the lower limbs. Some of these physical interventions demonstrate variable improvement in BMD
      in children with neuromuscular conditions, and some do not. A serious limitation in the
      previous work in this area is a failure to objectively measure the magnitude and duration of
      the loading experienced by the lower extremities. Thus, a lack of change in BMD may be due to
      the extremities experiencing only a fraction of the body weight (due to load-sharing with the
      assistive device) for an inadequate duration of standing time.

      Methods: In order to investigate the efficacy of standing treatment for increasing BMD, we
      will develop a simple, portable and inexpensive transducer that will measure the magnitude
      and time course of the load experienced by the lower extremities of individuals with SMA who
      use a stationary assisted standing device. This transducer will consist of an array of
      sensors embedded within a mat that will be placed under an individual's feet while they are
      in assisted standing. A prototype will be validated by comparing the output of this
      load-sensing mat against known loads that will be applied to the surface of the mat
      statically. The specific characteristics of the loading in the lower extremities of subjects
      can then be correlated with changes in their BMD to obtain a true outcome assessment. As a
      demonstration of this approach, we will recruit 3 children with SMA from Gillette Children's
      Specialty Healthcare who are currently participating in a standing program. Once enrolled and
      informed consent is obtained, the participants will use the mat provided to them to collect
      load and duration data during a baseline period where they will continue their standing
      program, and during a subsequent intervention period where they will increase the duration of
      their standing. The specific goal of this proposed project will be to develop, validate and
      establish the initial feasibility of such a measurement device.

      Implications: Successful completion of this proposed project will provide the necessary
      groundwork to move forward with a multicenter clinical trial on a large number of subjects
      with a variety of neuromuscular conditions. The measurement device will allow us to correlate
      change in BMD with the specific load history for each participant, thereby allowing us to
      determine whether physical interventions can lead to increased BMD in individuals with
      neuromuscular disabilities. Analysis of the data will help define a dose-dependent
      relationship between load, duration and changes in BMD, thereby guiding providers and
      therapists in prescribing standing interventions.
    

Intervention name(s): Assisted Standing Treatment Program
Intervention type(s): Other
Intervention description(s): Assisted Standing Treatment Program - Assisted standing treatment program will be gradually increase duration of standing by up to 75% after baseline.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: SMA; Neuromuscular disability