THE INTERCARPAL LIGAMENTS OF THE EQUINE MIDCARPAL JOINT .2. THE ROLE OF THE PALMAR INTERCARPAL LIGAMENTS IN THE RESTRAINT OF DORSAL DISPLACEMENT OF THE PROXIMAL ROW OF CARPAL BONES

Objective-To determine the relative contributions of the palmar interc arpal ligaments in the midcarpal joint to the restraint of dorsal disp lacement of the proximal row of carpal bones. Study Design-A biomechan ical study of cadaver equine carpi. Animals or Sample Population-Eight equine forelimbs from six thoroughbred horses. Methods-With joints in full extension, the radius was dorsally displaced while midcarpal joi nt displacement was measured. The restraining force at a joint displac ement of 1.5 mm was determined from the load-displacement curve. A lig ament or pair of ligaments was then cut and the testing procedure repe ated. Their contribution to restraining force was calculated as the pe rcentage change in restraining force after the ligament was sectioned. Relative cross-sectional areas of the ligaments tested were measured at the level of the midcarpal joint. Results-The collateral ligaments were the major contributors to the restraint of dorsal displace ment ( P < .001). In all joints, the palmar intercarpal ligaments contributed a greater proportion than the palmar carpal ligament (PCL) (P < .05). The mean percentage (+/-SEM) contributions to the restraint of dorsal displacement were 62.8 +/- 3.4 for the collateral ligaments, 14.5 +/- 1.4 for the PCL, and 22.7 +/- 2.2 for the palmar intercarpal ligament s. Mean cross-sectional area expressed as a percentage (+/-SEM) of the total ligamentous area were 9.0 +/- 0.3 for the palmar intercarpal li gaments, 27.1 +/- 3.0 for the PCL, and 63.8 +/- 2.8 for the collateral ligaments. Conclusions-Despite the small size of the palmar intercarp al ligaments, they play an important role in the restraint of dorsal d isplacement of the proximal row of carpal bones. Clinical Relevance-In terpretation, as well as prevention and treatment of intercarpal ligam ent tearing requires an understanding of their function. (C) Copyright 1997 by The American College of Veterinary Surgeons.