Anatomy and Biomechanics of the Thumb Carpometacarpal Joint

This article describes the anatomy and biomechanics of the thumb CMC joint, which is also often referred as the thumb trapeziometacarpal joint. The complexity of its anatomy, function, kinesiology, and stability allows humans to obtain the unique prehensile ability of thumb opposition with stable pinch. The biconcavoconvex saddle shape joints with offset mechanical axes allows a motion in 3 planes with only 2 axes of control. It is important to appreciate the unique oseous anatomy of the thumb CMC joint and role of supporting ligaments. Although many previous articles reported on the anterior oblique ligament as a primary stabilizer of the thumb CMC joint, increasing evidence has supported the dorsal ligament complex is its primary stabilizer. Understanding those key features of the thumb CMC joint is essential to adequately treat its pathology, such as fracture dislocation, ligamentous injury, and degenerative osteoarthritis.