The Role of the Antebrachiocarpal Ligaments in the Prevention of Hyperextension of the Antebrachiocarpal Joint

Objective
To evaluate the role of the medial collateral ligament, lateral collateral ligament, and the palmar carpal ligaments in the prevention of hyperextension of the antebrachiocarpal (AC) joint.
Study Design
In vitro experiment.
Animals
Cadaveric canine thoracic limbs (n = 12 pair).
Methods
Thoracic limbs from 12 healthy mixed breed dogs, free of carpal joint pathology, were assigned to 1 of 6 groups, defined by the order in which the ligaments stabilizing the AC joint were cut. The antebrachium, carpus, and proximal metacarpal (MC) bones were stripped of all muscle tissue, preserving the carpal joint capsule. After specimens were prepared for biomechanical testing, the manus was loaded using a system of weights and pulleys to extend the carpus. Extension was measured using a single motion tracking sensor fixed to the MC bones. All specimens were tested with all ligaments intact and after cutting each of the ligaments.
Results
Cutting each of the ligaments resulted in a significant change in the angle of extension of the carpus when compared with carpal extension with the ligaments intact. Cutting the palmar AC ligaments resulted in a significantly larger change in extension angle than occurred after cutting the medial and lateral collateral ligaments.
Conclusion
Each of the ligaments tested contribute to the prevention of hyperextension of the AC joint.