Detailed knowledge of the forces in the human body are of crucial importance to the successful design and implantation of prosthetic devices. For planning of rehabilitative exercises and development and prescription of orthotics devices, the influence of external forces in the internal equilibrium is of utmost importance. The AnyBody Modeling System is the ideal tool for this purpose because it is capable of capturing the true complexity of the musculoskeletal system.
A very large proportion of wheelchair users experience load-induced shoulder pain. This happens after several years' use, and it can be a very serious condition for an individual relying entirely on the arms for ambulation. The wheelchair parameters such as wheel diameter, pushrim position, axle position, and camber influence the shoulder forces during use. But precisely how?
This is a field where the consequences of a design change do not appear until several years of use. This alone makes experimentation impossible. But it is also ethically unacceptable to fit wheelchairs to humans in any other way than following best practice. In other words, computer simulation is the only way to gain knowledge about the influence of the wheelchair design on body loads.
The depicted model shown here investigates the gleno-humeral joint forces as a function of the axle position through a forward push on the pushrim. It is now possible to experiment with different design parameters to reduce the gleno-humeral forces as much as possible.