**7. Tissue banks**

oxide may be maintained in the graft and may interact or be released when in contact with any liquid, including blood. Gamma radiation may be toxic when in direct contact with fat that is present in the grafts [27, 37]. Autoclaving is another way to sterilise grafts. However, xenografts must be sterilised at a temperature of 132°C to inactivate infectious proteins, i.e., prions, though

Frozen grafts from tissue banks undergo several protocols for donor selection before being used for transplantation. Graft rejects are reported to reach 20 to 30% [4, 51]. But even with these severe protocols for selection, transmission of an infectious disease may occur [25, 53, 55, 59. Sugihara et al [53] in 1999 reported the presence of tumour cells in frozen femoral heads and suggested inclusion of histopathological examinations as part of the screening pro-

The lyophilisation process until now has not been linked with infection as confirmed by Shibuya et al. [48], Ledford et al. [29] and Ribeiro et al. [44] who also reported no clinical signs of infections in patients submitted to revision of total hip arthroplasty with acetabular reconstruction, as well as no case of bovine spongiform encephalopathy disease (BSE) and its new variant the Creutzfeldt-Jakob disease (CJD). It is believed that lyophilisation process chemically inactivates most of the bacterial agents, viral and prion agents to a safe and acceptable level to be used in humans as reported by Wenz et al. [63] and among us, by Galia et al. [16] and Rosito et al. [45].

Several bone grafts storage ways are used all over the world. The two most widely accepted

Extremely low temperatures (<−80°C) are achieved by using temperature-controlled freezers equipped with power generators, just in case of lack of electric power cut, and alarms triggered by the system when the temperature increases. In these special freezers, a bone tissue can be maintained for up to 5 years. It should be noted that very low temperatures do not have

Proposed and diffused by the Tissue Bank of USA Navy in 1951, the lyophilisation process became the technique in which bone is washed, centrifuged, decellularised, chemically degreased and subjected to physical processes of cleaning and sterilisation, and this way, only the protein-mineral matrix still remains in the graft, which is later frozen and then dehydrated. All these processes decrease antigenicity, tumour cell transmissions and inactivate prions [28, 35]. The lyophilisation is an important method of processing and storage for musculoskeletal tissues that allows not only the use of human bones, tendons and fascia (allogeneic) but also and mainly the bovine (xenogenic) [27, 31, 33, 39]. Currently, in major health centres, different types of bone grafts are available for reconstructive orthopaedic surgery: frozen and lyophi-

The frozen human graft (allogeneic) was the most used and widely accepted but the number of Tissue Banks in our country and in other developing countries is not enough to overcome the huge demand as well as the number of donors [47]. In the same way, as mentioned, there is a

lised autologous, (allogeneic) and lyophilised bovine grafts (xenogeneic) [2].

and used are the deep-frozen (−80°C) and lyophilisation ones.

a role in the sterilization of bone tissue.

this method reduces the mechanical resistance of xenografts in approximately 70% [62].

62 Bone Grafting - Recent Advances with Special References to Cranio-Maxillofacial Surgery

tocol for donor tissues [41, 53].

**6. Processing**

Musculoskeletal tissue banks such as in the USA, there is an institution – the American Association of Tissue Banks (AATB) – to regulate and supervise the functioning of all incountry tissue banks since 1976 [1]. In Brazil, however, is the Ministry of Health, under the regulation order No. 55 (Dec. 2015) [24] that provides the technical regulations for the functioning of musculoskeletal and skin tissue banks of human origin, determining guidance from the facility characteristics, screening of living donors or cadavers up to equipment and human resources [24]. These regulations, though quite strict, have greatly improved the quality of tissue processing and safe use. For accrual, the decision to accept or reject a donor is carried out by the chairman of the Bank of Musculoskeletal Tissues (BMST) after rigorous tests and following an established protocol [38]. As the protocols used by the Tissue Banks, one must consider the history, physical examination and laboratory tests of the donor (**Table 1**).



Source: Musculoskeletal Tissue Bank (BTME) of São Vicente de Paulo Hospital - Passo Fundo. Tissue Bank Unit of the

Biology of Bone Graft and the Use of Bovine Bone for Revision of Total Hip Arthroplasty…

http://dx.doi.org/10.5772/intechopen.79485

65

Hospital de Clínicas of Porto Alegre (UBMT-HCPA).

**Table 1.** Screening protocol for musculoskeletal tissue donors.


64 Bone Grafting - Recent Advances with Special References to Cranio-Maxillofacial Surgery


Source: Musculoskeletal Tissue Bank (BTME) of São Vicente de Paulo Hospital - Passo Fundo. Tissue Bank Unit of the Hospital de Clínicas of Porto Alegre (UBMT-HCPA).

**Table 1.** Screening protocol for musculoskeletal tissue donors.
