NONGRAFTED AND GRAFTED OSTEOTOMIES OF PROXIMAL SESAMOID BONES OF THE HORSE

A radiographic study of healing patterns of nongrafted and grafted basilar osteotomies of proximal sesamoid bones in 14 horses was performed. Osteotomies were created in one proximal sesamoid bone of each fromt leg. One was treated by an autogenous rib graft, and the other was left nongrafted. Wedge-shaped cortical bone, corticocancellous bone with multiple drill holes, and chips of cancellous hbone were used as autogenous grafts. Presurgical, surgical, and postsurgical radiographic examinations were performed. The longest follow-up period was 40 weeks. High detail radiography of 3-mm bone sections and microangiography were also perofromed. Radiographic interpretation of lack of bone healing was erroneous in approximately one-half of the cases. Lack of an external bridging callus was incorrectly interpreted as lack of bony union. If noted, periosteal new bone formation failed to develop into a pattern of bridging callus. Radiographs did not permiit detection of the osteotomy line entering the articular surface or displacement of distal fragments. From angiography obtained ten weeks after surgery, the pattern of blood supply was similar in nontreated and grafted sesamoid bones. Microangiography showed rich vascularization of the cancellous graft and callus, reflecting good healing activity, whitle vascularization of the osteotomy site was absent in the nontreated osteotomies.