EFFECTS OF EXPERIMENTAL DESMOTOMY ON MATERIAL PROPERTIES AND HISTOMORPHOLOGIC AND ULTRASONOGRAPHIC FEATURES OF THE ACCESSORY LIGAMENT OF THE DEEP DIGITAL FLEXOR TENDON IN CLINICALLY NORMAL HORSES

Objective-To evaluate posttrauma biomechanical behavior of the scar at tributable to desmotomy of the accessory ligament of the deep digital flexor tendon (AL-DDFT), compared with the histomorphologic and ultras onographic appearance. Animals-5 Standardbred trotters. Procedure-Gros s appearance, length, cross-sectional area (CSA), in vitro material pr operties, and ultrasonographic and histomorphologic features were stud ied 6 months after desmotomy. Tensile tests were conducted with forces and elongation simultaneously recorded. Surgically treated limbs were compared with nontreated contralateral limbs. Results-The CSA of the treated ligaments was increased threefold, and treated ligaments were 1 cm longer than control ligaments. In the healed AL-DDFT, stress and material stiffness were approximately a third of those values for cont rols. The functional characteristics, force and elongation at failure, reached 80% of control values. Ultrasonographic and the histomorpholo gic examination of the scar tissue revealed high amounts of randomly o riented collagen. Conclusion-From the ultrasonographic and histomorpho logic findings and the material properties, it was concluded that the scar tissue was of inferior quality. However, the functional propertie s had been restored for the most part by increase of the CSA. The leng th increase may lead to strain relief in the AL-DDFT after desmotomy. Clinical Relevance-Desmotomy is recommended as treatment for chronic d esmitis.