Bone grafting of cryosurgically treated bone defects : experiments in goats

It is hypothesized that cryosurgically treated bone defects are inappropriate host sites for cancellous bone grafting. The influence of autologous cancellous bone grafting on the healing of cryosurgically treated gap defects of long bones was investigated. A unilateral in vivo experiment was done to study bone strength and graft incorporation in the goat. The lining of a cylindrical defect of the femoral diaphysis was treated with a closed liquid nitrogen cryoprobe in 62 goats. Thirty-one animals received an impacted, morselized, cancellous bone graft harvested from the sternum. The other 31 animals served as controls. At 0, 4, 7, 10, 13, 16, and 26 weeks animals were euthanized and the femurs were evaluated for torsional strength, computed tomography, and histologic assessment. Specimens with a bone graft showed no significant increase in torsional strength with time compared to the controls. In all goats euthanized at 10 weeks or later, the graft was resorbed. The amount of bone apposition at the site of the cryosurgical lesion and the time at which the defect was bridged were similar in both groups. Autologous cancellous bone grafting does not accelerate healing of cryosurgically treated, stable, diaphyseal defects in the goat.