The intermetacarpal joints are the small synovial joints between the bases of the second through fifth metacarpals, communicating with each other and with the carpometacarpal joints in a common joint cavity. The joint capsules are reinforced by palmar and dorsal intermetacarpal ligaments and the deep transverse metacarpal ligament distally. Motion is minimal, consisting of slight gliding to allow slight spread of the metacarpal bases during grip.
The intermetacarpal joints share a synovial cavity with the CMC joints (2nd-5th), meaning CMC joint injections or arthroscopy can access the intermetacarpal space and vice versa. Inflammatory arthritis, particularly rheumatoid arthritis, commonly involves these joints, producing dorsal swelling and interosseous muscle atrophy. Intermetacarpal joint disruption accompanies fracture-dislocations of the metacarpal bases, requiring anatomic reduction to restore the transverse metacarpal arch.
Axial loading through the fingers disrupts the intermetacarpal joints along with the CMC ligaments, allowing dorsal dislocation of metacarpal bases that require open reduction and percutaneous pinning to restore the metacarpal arch and grip function.
Inflammatory pannus within the intermetacarpal and CMC joint cavities produces dorsal metacarpal head prominence, progressive interosseous muscle atrophy, and eventual ulnar drift deformity of the MCP joints, managed with systemic disease control and reconstructive hand surgery.
