Comparison of two surgical procedures for arthrodesis of the proximal interphalangeal joint in horses.

Arthrodesis of the proximal interphalangeal joint in horses, with 2 screws crisscrossing the joint, was compared with arthrodesis achieved by placement of 3 screws crossing the joint parallel to the long axis of the bone. The comparison was made by means of radiography, gross and histologic examinations, and motion evaluation. Additionally, the fused 1st and 2nd phalanges resulting from each method were subjected to breaking forces. Motion evaluation and direct examination of the fused area demonstrated that either procedure can be used to achieve arthrodesis consistently, and the breaking procedure indicated that the fused joints were as strong or stronger than areas penetrated by the cortical screws used in internal fixation. The fused area resulting from the parallel procedure was stronger than that from the crisscross procedure. The parallel procedure was easier, gave better alignment of 1st and 2nd phalanges, and was prone to less error in screw placement. It was concluded that arthrodesis by either procedure was satisfactory for treating osteoarthritis and related problems of the proximal interphalangeal joint in horses, but that the parallel procedure created a superior union between the 1st and 2nd phalanges during the first 120 postoperative days.