Effect of beta-tricalcium phosphate in surgically created subchondral bone defects in male horses

beta-Tricalcium phosphate (TCP) was evaluated as a synthetic bone grafting material in horses. Sixteen horses were randomly assigned to 4 groups of 4 horses. In each horse, an 11-mm by 10-mm circular defect with a smooth margin was created surgically in the weight-bearing surface of both third metacarpal bones (McIII) and the left third metatarsal bone. The defect in the left McIII was filled with TCP, the defect in the right McIII was filled with a mixture of 50% autogenous cancellous bone (ACB) and 50% TCP, and the defect in the left third metatarsal bone was not filled to serve as a control. Nuclear imaging and radiographic evaluation of surgical sites were performed at postsurgical week (PSW) 4 and 13 in group-I horses and at PSW 26, 39, and 52 in groups-II, -III, and -IV horses, respectively. Horses in groups I, II, III, and IV were euthanatized at PSW 13, 26, 39, and 52, respectively, and specimens were harvested for histologic evaluation. Results were compared among treatment methods, as well as among time intervals. The greatest activity at defect sites was seen in group-I horses at PSW 4. Activity counts in limbs of group-I horses at PSW 13 and counts in limbs of group-II horses at PSW 26 were not significantly (P less than or equal to 0.05) different. Activity counts in groups-III and -IV horses at PSW 39 and 52, respectively, were less than those in groups I and II. However, there was no significant difference in activity counts between limbs implanted with TCP or ACB:TCP.(ABSTRACT TRUNCATED AT 250 WORDS)