Control of Osteoporosis

The hidden problem of decreased bone mineral density resulting from immobilization places non-ambulatory children at risk for osteoporosis and consequent bone fracture in their early adult years. Recent studies have shown that the reciprocal mechanical loading of the long bones provided in walking and more rigorous exercise contributes to increased bone density. This project has developed a modular actuator that can be added to commercially available rehabilitation standing devices, allowing short term shifting of weight-bearing between the two legs of a non-ambulatory child. Bone mineral density measurement will be used to assess the benefits of this intervention.

Passive standing has shown mixed conclusions on successfully increasing bone mineral density. Preliminary studies on physical activity and low-magnitude, high-frequency vibration have yielded more promising, positive results for maintaining and increasing bone mineral density. Led to design of a dynamic stander to apply reciprocating forces that mimic the walking gait to the lower limbs of immobilized children.

Design and Development
- Joint contractures, spasticity and hip dislocations common so vertical displacement and hip/knee rotation must be kept minimal
- Incorporate device into existing standers. Prospect Design modified as currently used at CSH. Current stander provides required head and trunk support, prevents hip and knee rotation, maintains stability of stander and adjustability of trunk angle and pads and straps are not modified so placement procedures do not change
- Used in hospital and school settings. The pneumatic actuator chosen as relatively quiet compared to electric motors. It uses a hospital grade compressor that minimizes noise and maintains sterility
- Software and circuitry: MatLab script written with graphical user interface for therapists
- Safety guards: mechanical guards prevent surpassing maximum desired displacement. There is a system shut-down button in case of emergency, gate over plates and mechanical components.

Current Work and Evaluation
- Trial with two healthy subjects complete. Verified mechanical design. August 2007 and December 2007
- Thirteen week pilot study with two subjects at CSH in Mountainside, NJ has been completed
- Twelve month study with subjects at Fanwood Preschool in Fanwood, NJ set to begin in November 2008