Biomechanics of the shoulder

The shoulder joint takes a special position among all the other joints of t he human body because of its special requirements of stability and mobility . Knowledge of the biomechanics of the shoulder joint forms the basis for t he development of modern concepts of reconstructive surgery and arthroplast y. Most of the biomechanical findings are the result of research performed on cadaver shoulders using increasingly sophisticated methods of measurement. These studies elucidate the interaction of the static and dynamic factors w hich contribute to the delicate balance of the glenohumeral joint. Recently performed research is increasingly being focussed on more detailed analyse s of muscle forces and stress distribution in the subchondral bone and peri articular soft tissues. The efficiency of the computer systems now availabl e has enabled the development of complex, virtual shoulder models and three -dimensional finite element analyses. In the future a pure mechanical understanding has to be modified to extend to a concept which includes more data obtained from living subjects, especi ally with regard to muscle activity under varying loads and neuromuscular f eedback systems which currently are difficult to assess.