The effect of compacted cancellous bone grafting on the healing of subchondral bone defects of the medial femoral condyle in horses

Objective-To compare the quality of second-intention healing and that of co mpacting sternally harvested cancellous bone into subchondral bone defects of the medial femoral condyle in horses. Study Design-A controlled experiment using a surgical technique that minimi zes soft tissue trauma, customized for consistency among horses. Animals or Sample Population-Ten horses, aged 2 to 5 years, free of hindlim b lameness and with radiographically normal stifles. Methods-After a 12.7-mm-diameter x 19-mm-deep defect was created into rando mly selected medial femoral condyles, bone and cartilage healing was evalua ted over a 6-month period in control horses (n = 5) and horses receiving a compacted cancellous bone graft (n = 5). Healing was evaluated using lamene ss assessment, radiographic and microradiographic interpretation, arthrosco pic appearance, percent bone fill, proteoglycan content, and histology. Results-Six months after surgery, there was no significant difference betwe en grafted and ungrafted defects with respect to lameness, radiographic sco re, or percent bone fill. Histologically, grafted defects were characterize d by the presence of dead graft and secondary cyst formation in four defect s. Ungrafted defects filled with fibrous tissue and no cyst formation were identified. Conclusions-Grafted defects do not heal better than ungrafted defects, and lameness was not affected by surgical technique. Clinical Significance-Cartilage healing is similar in grafted and ungrafted defects in the equine medial femoral condyle at 6 months, suggesting that surgical debridement alone of cystic structures remains the treatment of ch oice. (C)Copyright 2000 by The American College of Veterinary Surgeons.