Three-dimensional kinematic analysis of the second through fifth carpometacarpal joints

Multiple Carpometacarpal Dislocations of the Hand – An Uncommon Variant: A Rare Case

“…1,4) However, the ulnar-side CMC joints are more mobile than radial CMC joints. 5) CMC joint dislocations are often associated with concomitant carpal fractures or metacarpal base avulsion fractures due to the strong attachments of the carpometacarpal ligaments. 2,6) When these ligaments remain intact, the resultant forces produce avulsion fractures instead of dislocations.…”

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“…The congruity of the corresponding joint surfaces creates a complex, irregular structure of interlocking bony articulations that confer static stability to the CMC joints. The third CMC joint occupies a central position in a slightly more proximal position compared to the adjacent joints in a manner that produces the stable keystone phenomenon, very much like the base of the second metatarsal at the tarso-metatarsal (Lisfranc) articulation [4]. The buttressing effect created by the side-to-side articulation of the metacarpal bases provides additional stability, particularly to the middle and ring finger CMC joints [4].…”

“…The third CMC joint occupies a central position in a slightly more proximal position compared to the adjacent joints in a manner that produces the stable keystone phenomenon, very much like the base of the second metatarsal at the tarso-metatarsal (Lisfranc) articulation [4]. The buttressing effect created by the side-to-side articulation of the metacarpal bases provides additional stability, particularly to the middle and ring finger CMC joints [4]. Adding stability to the inherent bony "lock in" are volar, dorsal and intermetacarpal ligaments.…”

“…Divergent dislocations are even rarer [5]. When looking at the individual rays, the ulnar CMC joints dislocations are more commonly dislocated than the second and third CMCJs due to the increased mobility at the ring and little finger MCP joints which renders these joints relatively less stable [1,4,27]. These dislocations tend to be more common in young males [7].…”

Management of Intra-Articular Metacarpal Base Fractures of the Second Through Fifth Metacarpals

“…However, the stability provided by these ligaments decreases sequentially in a radial-to-ulnar direction, and much more motion exists at the fourth and fifth carpometacarpal joints than at the second and third carpometacarpal joints. 15 The increased mobility at the fourth and fifth carpometacarpal joints leads to increased fracture instability at the fourth and fifth metacarpal bases. Also, tendon insertions of the extensor carpi radialis longus, extensor carpi radialis brevis, and the extensor carpi ulnaris can lead to avulsion fractures of the second, third, and fifth metacarpals, respectively, which may prove difficult to appreciate on plain radiographs.…”