The ligament and skeletal anatomy of the second through fifth carpometacarpal joints and adjacent structures.

A detailed and comprehensive study of the anatomy of the 2nd through 5th carpometacarpal (CMC) joints and adjacent structures and clinical relevance is reported. Multiple dorsal ligaments were identified, including 2 from the 5th metacarpal (MC), 2 from the 4th, 3 from the 3rd, and 2 from the 2nd. There were also multiple volar ligaments, 1 from the 5th MC, 1 from the 4th, 4 from the 3rd, and 1 from the 2nd. There was only 1 intra-articular ligament, which was located between the 3rd/4th MC and the capitate/hamate and provided stability even when the dorsal and volar CMC ligaments were cut. There was more variability and often multiple distinct joint surfaces or facets forming the articulations between adjacent MCs and/or adjacent distal carpal bones. The joint surfaces between the 4th MC and the capitate and/or the hamate were also variable and had 5 different types of articulation. The area of the 2nd and 3rd CMC joints was found to have the highest incidence (18%) of carpal coalition, and when present there was a dorsal bone prominence and an absence of the normal dorsal ligament anatomy.