Thumb metacarpophalangeal ulnar collateral ligament injuries: a biomechanical simulation study of four static reconstructions.
OBJECTIVE
To determine the optimal tunnel placement positions for tendon graft reconstruction of chronic thumb metacarpophalangeal (MCP) ulnar collateral ligament injuries that would stabilize the joint while maintaining motion.


METHODS
Four commonly used tunnel placement methods were simulated on a cadaveric model using fresh-frozen thumbs and a suture/screw construct. The methods were as follows: (1) triangular configuration with apex proximal, (2) triangular configuration with apex distal, (3) cruciate configuration, and (4) parallel configuration. Stability was tested by valgus loading at 0 degrees and 30 degrees , and range of motion was tested by loading the thumb tendons. Statistical analysis was performed by 1-way analysis of variance testing.


RESULTS
Valgus load stability testing at 0 degrees and 30 degrees showed that all 4 reconstruction methods stabilized the MCP joint compared with the fully sectioned state. The amount of stability achieved was not significantly different between the 4 methods. Only the reconstruction method, however, with a triangular configuration with the apex proximal restored flexion/extension range of motion not significantly different from the intact state. The other 3 methods resulted in significantly decreased range of motion.


CONCLUSIONS
The reconstruction tunnel positioning of triangular configuration with apex proximal stabilizes the thumb MCP joint while maintaining flexion/extension range of motion. We recommend this configuration for chronic MCP joint injuries in which the native ulnar collateral ligament is inadequate and tendon graft reconstruction is performed.
Lee
Steve K
SK
Department of Orthopaedic Surgery, Hospital for Joint Diseases/New York University School of Medicine, New York, NY 10029, USA. steve.lee@msnyuhealth.org
Kubiak
Erik N
EN
Lawler
Ericka
E
Iesaka
Kazuho
K
Liporace
Frank A
FA
Green
Steven M
SM
D001696:Biomechanical Phenomena; D017885:Collateral Ligaments / Q000293:injuries / Q000601:surgery*; D006225:Hand / Q000601:surgery; D006230:Hand Injuries / Q000601:surgery*; D006801:Humans; D007593:Joint Instability / Q000601:surgery; D008662:Metacarpophalangeal Joint / Q000293:injuries / Q000601:surgery; D019637:Orthopedic Procedures / Q000379:methods*; D013710:Tendons / Q000637:transplantation; D013933:Thumb / Q000293:injuries / Q000601:surgery*; D014184:Transplantation, Homologous; D014457:Ulna