Orthotopic bone transplantation in mice. I. Technique and assessment of healing

A technique for orthotopic bone transplantation in mice has been developed. A section of recipient tibia was removed and replaced by a similar section from the donor animal. The graft was held in place by internal fixation. Bone healing was assessed clinically, histologically, radiologically, and by torsion testing. The most objective measurements of bone healing were the maximum torque and the energy absorbed by the bone to failure, which were derived from torsion testing. The degree of bone healing in donor-recipient combinations differing at H-2, non-H-2, or H-Y antigens was compared to the degree of healing in syngeneic controls. The incidence of nonunion was significantly increased in the H-2-disparate group. Furthermore, the extent of bone healing as measured by torsion testing was significantly reduced in both the H-2-and the H-Y-disparate groups. Thus, in the strain combinations tested, the order of importance of the genetic disparities influencing allogeneic bone grafts was H-2 greater than H-Y greater than non-H-2. The impaired healing of allogeneic bone grafts was probably immunologically mediated, as suggested by the observation that recipients of bone allografts rejected subsequent skin allografts in an accelerated manner.