Biomechanics of the spine

Abstract

The bio-mechanical properties of the vertebral segment, the elastic behaviour of the ligaments and the viscous effect of the nucleus are arguments based on a mathematical model. It follows that considering the centre of rotation of a spinal segment to be like a transient pole permits evaluation of several positions and helps the recognition of when an abnormal mobility is involved. A computer simulation for the establishment of an ideal individual posture has also been developed. Three assumptions are made: the lumbo-sacral angle, the shape of the thoracic kyphosis and the position of the head. From the hypothesis that the sum of all the angular momenta involved should exert a minimal stress on the pelvis, the human upright position can be regarded as an optimal equilibrium between evolutionary, organ related presumptions and physical facts. From a bio-mechanical basis of postural disorders, primary or secondary causes are discussed as well as the basic causes of pain. After discussion of the several causes of faulty posture, a special emphasis is placed on prophylaxis. Proposals for early recognition of causes of faulty posture in schools, in places of work and on an ergometric basis are presented.