gms | German Medical Science

Clinical issue/s: The Trapezio-Metacarpal joint (TM'J) is the second most common joint afflicted by Osteoarthritis in the hand (following DIP'J), and it is the most common surgically treated arthritic joint in the upper extremity. Age and gender are two factors related to risk of Osteoarthritis of this joint. Studies have indicated a prevalence of 16-40% among post-menopause women. Common treatments include physical therapy (splints, thermo-therapy, massage, intrinsic muscles strengthening, teaching self-management), medication (NSAID), injections (corticosteroid, hyaluronic acid), and surgery. In this presentation we review the anatomical structure of the trapezium and 1st metacarpal bones, the geometry and the biomechanics of this joint, and its surrounding ligaments. Furthermore, the weakness of the joint and the forces applied on it during rotation of the metacarpal on the Trapezium are described. These structural aspects are reviewed within a phylogenetic development framework, which emphasizes the differences between human and other apes' hands. Within this concept, evidence of thumb development (studies of fossils), is briefly reviewed. The morphological evolution of the thumb through cultural developments and functional requirements are illustrated. Finally, several questions regarding prevention of TM'J osteoarthritis and future technological and functional influences on the continued evolution of the thumb are introduced.

Clinical reasoning: Preventing the TM'J Osteoarthritis by adjusting future tecnological equipment to the biomechanics of the thumb.

Innovative, analytical or new approach: Understanding the phylogenetic development of the thumb, integrating the biomechanics of this joint.

Contribution to advancing HT practice: Understanding the biomechanics of this joint can be helped by educating patients to use correct position of the hand grip, and to be creative in developing ergonomic equipment.