Review of the literature on cryopreservation of bone

Abstract

A review of the pertinent literature applying to the clinical and histological evaluation of grafts of cryobiologically preserved bone has been presented. Our concepts today of the nature of the host response to bone implantation are only slightly changed from that proposed by some writers near the turn of the century. In general, the replacement of bone implants is by resorption and substitution, largely mediated by the host tissues. Histologically, cryobiologically preserved homogenous bone grafts are accepted by the host in much the same manner as are osseous autografts. However, the rate of replacement of homografts is much slower, with the processes of resorption and replacement being retarded in comparison with the autogenous counterparts. It appears that in certain selected operative sites such as cystic bone defects and spinal fusions, properly preserved homogenous bone implants may be clinically as effective as autogenous grafts. The consensus of published reports indicates that the various acceptable cryobiological methods of storage of homogenous bone have no uniquely identifiable effect on clinically detectable results. Although reports are conflicting, it appears that in general, properly prepared frozen bone and freeze-driéd bone are equally effective when used as nonviable homografts. The application of cryobiological technies to the storage of heterografts has not to date produced an osseous implant material which could be substituted generally for the fresh autograft or even the properly preserved homograft. It appears that more efficacious application of cryobiological procedures to bone preservation will depend upon the resolution of many fundamental questions relating to orthopedic immunology. These areas would include the characterization of the histocompatibility antigens of bone, and the efficacious welding of immune physiology and histopathological techniques into a new “cellular immunology,” which may prove to be the most meaningful parameter of graft evaluation.