Biomechanics of orthoses for the subluxed shoulder.

Based on biomechanics several operational principles for the neutralization of a shoulder subluxation are described. The pros and cons of the operational principles are discussed. A detailed analysis of the forces acting on the upper and lower arm indicates a preference for only one of the operational principles and explains why the arm sling and hemisling fail in the elimination of subluxation. With the operational principle selected a shoulder orthosis has been developed. Clinical results are given.