[Anatomy and physiology of the human trapezometacarpal joint]

Biomechanics of the trapeziometacarpal joint (TMJ) are controversial, because of differences between its normal anatomical description and theories of its pathophysiology. The aim of this article is to explain the mechanisms underlying trapeziometacarpal osteoarthritis by means of the anatomy and physiology of the TM joint. Having described the main ligaments and their roles in the physiology of the joint, it is then difficult to understand why trapezectomy usually improves patients with TMO, when the ligaments are destroyed or only partially repaired by tendinoplasty. Different explanations of TMO are detailed but it seems, according to the literature, that TMO can be explained more by genetic considerations than anatomic dysfunction. The theory of Zancolli is not verified by facts, and other concepts such as ligament theory, and dysplasia of the caudal aspect of the trapezial bone are not sufficient to understand this disease. The same discussion is engaged with regard to explaining the automatic rotation of the thumb in the TM joint. The cantilever bending principle is described as proposed by Bettinger and al.