Intra-articular kinematics of the upper limb joints: a six degrees of freedom study of coupled motions.

In sport, leisure and certain occupational activities, joint lesions of the upper limb are very common. To understand their aetiology in order to prevent and treat these pathologies on a scientific basis, a comprehensive knowledge of the involved stress and kinematics is imperative. For many years intra-articular joint kinematics have been described hypothetically in terms of the convex-concave principle.