Revision joint replacement, tumor surgeries and reconstruction surgeries for the large bone defects cannot be developed fully in the place where the facility of bone banking is not available.

There have been numerous accounts of a wide variety of preservation techniques (refrigeration, freezing, freeze-drying, thimerosal, alcohol, demineralization, deproteinization, boiling, autoclaving, and others), banking methods, and clinical and laboratory studies in support of the biological potential of stored grafts.

Fresh autogenous bone and cartilage are regarded as the most effective biological resource for repair or reconstruction of the skeletal system. Allogeneic rather than xenogeneic tissues are generally preferred when a biological alternative to a fresh autograft is sought, and bone banks exist for the purpose of supplying the surgeon with safe and effective skeletal tissues that are suitable for their intended clinical application and are available whenever the need arises.

The use of any substitute for autogenous tissue requires consideration of its biological and biomechanical potential as a graft material and of the possibility of transfer of disease from donor to recipient, as well as the presence and significance of immune responses to foreign antigens. Methods chosen by bone banks for donor selection and for acquisition, processing, and storage of tissues for clinical transplantation must address these concerns for efficacy, safety, and biocompatibility.

Bone banks have been developed according to guidelines for the banking of musculoskeletal Tissues world over.

Both cadaver and living donors may be acceptable, provided there is information pertaining to the medical history and the circumstances surrounding the cause of death (in the case of cadavera) sufficient to exclude individuals with potentially serious transmissible diseases or in whom the biological properties of bone or cartilage may be compromised in terms of its intended application. Particular attention is paid to the presence of systemic infection (bacterial, viral, or fungal) or infection of those portions of the body to be collected as graft material, malignant disease, diffuse or systemic disorders that may compromise the biological or biomechanical integrity of the skeleton, toxic substances in toxic amounts, venereal diseases, and diseases of unknown etiology. Laboratory tests for identification of hepatitis and venereal diseases and a complete and unrestricted autopsy following removal of tissues from cadaver donors should be routinely used to supplement the medical history.

Although specific time constraints following death have not been established for musculoskeletal tissues, it is generally regarded as optimum to remove potential grafts and subject them to methods of preservation as rapidly as possible, preferably within twenty-four hours of death provided the body has been refrigerated during this period. Acquisition of tissues may take place under aseptic conditions or else may be accomplished in a clean but nonsterile fashion, in which case a secondary method for tissue sterilization is necessary. The sterile procurement of tissues requires application of the same principles involved for any surgical procedure, including use of an operating room or similar facility, with sterile preparation of the skin and draping in a sterile fashion.

Preservation techniques, as just mentioned, most commonly involve freezing or freeze-drying, and are

applied as rapidly after tissue procurement as possible. At the present time, bone is stored in a non-viable (albeit biologically useful) state, but recently more attention has been focused on methods to provide chondrocyte viability. The percentage of functional chondrocytes required to sustain the articular matrix is unknown.

Frozen allografts are usually stored in sufficient plastic or cloth wraps, or both, to ensure maintenance of sterility and to retard evaporation of water that would lead to drying of tissues. Grafts remain frozen at the desired temperature until ready for use, during which time the storage environment is monitored by recording devices and appropriate alarm systems. Freeze-dried (lyophilized) grafts must be placed in sealed evacuated containers - either plastic or, more commonly, glass - and may then be stored at room temperature. The length of safe storage for preserved bone allografts is unknown. Based on our knowledge of retarding autolysis by cold, lower freezing temperatures are presumed to extend the so-called shelf life of grafts. Indeed, grafts frozen to -70 degrees Celsius have been stored for several years and then successfully used clinically. Theoretically there is no limit to the length of time that freeze-dried tissues can be retained for future transplantation provided the storage vacuum remains in tact. In general, the storage conditions must be maintained until shortly before clinical application of the graft. If transit time is required between the bank and the operating room because of geographical separation, then methods to ensure storage conditions during delivery must be applied. Frozen grafts are usually thawed in the operating room in warm physiological solutions just prior to use. Freezedried allografts may require reconstitution with water or saline if any shaping, cutting, or fixation is to be employed. The period of time that is required to return the biomechanical properties of freeze-dried bone to normal depends on the size and shape of the graft. Crushed chips of bone to be used for filling cystic cavities do not require any rehydration, while massive segments of long bone may need eighteen to twenty-four hours of exposure to sterile physiological solutions.

The presence of immune responses to bone and cartilage allografts has been confirmed in clinical circumstances involving fresh, frozen, and freeze-dried osteochondral allografts, and the nature of these responses appears to parallel animal studies performed in the past. Investigations in humans have been confined to cellsurface antigens (HL-A), which evoke responses in virtually all recipients of fresh grafts, in most individuals treated with frozen tissues, and in a small but definite pro portion of patients receiving freeze-dried bone. It is worth noting that gross clinical success has not, as yet, been correlated with sensitization to this cell-surface antigen system. Other potential sources of antigen in human osteochondral allografts (especially matrix components and, perhaps, collagen) have not been the subject of reports to date but require definition. Furthermore, the significance of these responses must await more comprehensive studies that objectively quantitate immune responses and correlate them with sensitive parameters of biology and biomechanics.

In the past, bone banks have been either major regional or national facilities, often engaged in the banking of multiple tissues and organs and serving a large population and geographical area, or smaller banks, usually concerned with a single tissue for use in one institution. Major banks, by their very nature, have been quite visible and accessible to the extent of their limited resources and the priorities of their sponsors.

In India we have numerous Musculoskeletal Tissue Banking systems at renowned hospitals of the country like, AIIMS, Ganga Hospital, Tata Memorial Hospital, Chennai General Hospital etc.