Selection has to be rigorous so that there is no risk of the transmission of iatrogenic pathology to the host through the graft. This requires adequate knowledge of the history of the illness and the circumstances of the accident, as well as the medical history of the donor. There are many absolute contra-indications. Subjects with a cancerous condition, a systemic illness, collagenosis, an auto-immune disease, or bone dystrophy may not have tissue removed for grafts. We systematically eliminate from the list of donors those suffering from a viral, bacteriological, or parasitic infection, mycosis or tuberculosis as well as those with risk factors and those who have been on artificial ventilation for more than 72 h in intensive care, as they are potentially infected. As far as the validation of the grafting material is concerned, the banks have to conform to the legislation in force decreed by the French Graft Institute.

Bacterial decontamination is performed using a solution of antibiotics consisting of rifocine and chloramphenicol.

Samples are taken from each graft before and after decontamination and after thawing. Positive bacteriological results will mean that the tissues will have to be destroyed.

Blood samples have to be taken from each donor (live or deceased) in order to perform the obligatory virological examinations.

In accordance with the decrees of 25 February, 1992, of 24 May, 1994, and of 24, July 1996, medical biological analyses are performed to test for infection:

Decree No. 97–928 of 9 October, 1997 removes the obligation to carry out a search for the agent responsible for toxoplasmosis, for infection by cytomegalovirus, and by the Epstein-Barr virus. The Decree of 1 April, 1997 requires that the results of the examinations performed are examined before the patients have been transfused, as any hemodilution could falsify the tests. Finally, the French Blood Agency and the French Graft Institute recommend that the tissues are placed into quarantine and that the virological tests are repeated 4–6 months after the tissue has been removed. These samplings are performed either on the live donor or on the host of organs coming from the same donor and are performed to reduce the risk in the event of the tissue having been removed during a seroconversion phase. However, placing these products into quarantine is only one of the possible ways of ensuring safety. A decree will specify the conditions under which it is to be performed in the various situations according to the other methods which could be used, in particular directly testing for the viruses by molecular biology techniques (PCR).

As the risk of infection is the main concern in this surgery, the various stages of surgery must be performed under the strictest aseptic conditions possible. The tissue therefore has to be removed in an operating theatre, according to the same principles as regulated orthopedic surgery, and it is considered that a maximum time lapse of 6 h from the circulation stopping can be reasonably accepted. For joint removals, the whole of the joint capsule is preserved as well as the intra-articular ligaments and the menisces or labra. In the case of the knee, and in order to keep the extensor apparatus intact, we retain the whole of the patellar tendon continuously with the posterior half of the patellar joint. This is also continuous with the quadricipital tendon, the upper part of which is cut into an inverted V. The muscular insertions are scraped and the surgeon removing the tissue cleans all the bone attachments of the ligaments allowing the capsule to be refixed firmly. The part is then placed in a bag which is resistant to very low temperatures (captonteflon bags). The reconstruction of the skeleton is one of the important stages of the removal. It is a legal obligation and it has to be as perfect as possible.

In order to find the desired bone fragment again easily in the bank, it is necessary to fill in the data sheet carefully and to perform X-rays without enlargement or with an enlargement control placed side-by-side with the bone part.

All the bone banks have to be inspected periodically, and samplings are performed on a very regular basis (20 % of the grafts are rejected annually, either immediately after having been removed on account of positive results being found in tests or subsequently at the 6-month checks).

Many preservation methods have been suggested since the use of allografts was first considered. The techniques of irradiation and sterilization by moist heat will be described in detail subsequently. Cryopreservation is the only current procedure which makes it possible to preserve bone fragments and in particular cartilage cells safely.

Drying under vacuum or lyophilization uses plasma preservation processes. These grafts, which are theoretically usable indefinitely at ordinary temperatures, are fragile and are not sufficiently strong in mechanical terms to withstand the usual mechanical stresses and, in particular, all the cells are destroyed preventing the use of friction surfaces.

Irradiation of bone fragments taken under conditions which are not sterile is recommended by some teams who see a practical advantage for taking grafts. However, not only does this irradiation, conventionally performed at 25 K Gray, not guarantee perfect viral sterility but it also causes the destruction of all the cells.

Since 1981 we have been using cryopreservation of massive osteocartilaginous grafts in liquid nitrogen at −196 °C. This method makes it possible to preserve whole bones and complete joints over an extended period as it preserves the viability of the cartilaginous cells, the fibers, and fibroblasts contained in the ligaments and capsules.

Without going into the technical details of cryopreservation and storage, we would like to underline the fact that tissue preservation has to obey two essential rules:

To avoid the formation of ice macrocrystals, it is necessary to impregnate the bone, cartilage, and ligament tissues with a suitable cryoprotector. At Marseilles, we use a mixture of macro-molecules (4 % human albumin which is to be replaced by Héloes) and 10 % final DMSO. This solution is maintained at a temperature of 4 °C because DMSO is toxic. In theory, the “deep cold” should enable these objectives to be reached by stopping the action of the tissue enzymes. If relatively moderate freezing temperatures are used (higher than −20 °C), the enzymes present in the tissue are not inactivated and will destroy the architecture of the graft in a few weeks. At −80 °C (limit of electric freezers), although the enzymatic activity is clearly reduced, it is not totally stopped, only collagenase is inactivated at this temperature. At −196 °C all the enzymes are inactivated and the proteins can be preserved over an extended period. On the other hand, DMSO has a eutectic point around −60 °C, at this temperature, the microcrystals of ice can recombine into macro-crystals and make the cells burst. For the same reasons, the temperature of the graft cannot be lowered in an haphazard fashion, and it is necessary to vary the rate at which this takes place in accordance with the temperature obtained. The optimum curve seems to us to be 2 °C per minute down to −40 °C then 5 °C per minute down to −140 °C, the temperature at which the graft is then placed in nitrogen vapor, directly in the tank where it is stored.

Thawing, on the other hand, has to be rapid so that the largest number of cells remain alive. Physiological serum or Ringer’s lactate solution at 40–41 °C will be used to thaw out and wash the grafts in order to eliminate the DMSO. Approximately 2 h after having removed the bone fragments from the liquid nitrogen tank, they are usable for a period of approximately 24–26 h, which means that they can be taken to any part of France and Europe. However, donors are becoming rarer and rarer and it is becoming increasingly difficult to obtain tissue.

The mechanical strength of the cortical allograft is only 50–60 % of the strength of normal bone during a period ranging from the 8th to the 18th month after the graft has been implanted (on account of the revascularization of the bone). Maximum fragility is at around the 12th month and it is only after 2–3 years after the graft has been implanted that the bone regains normal density and biomechanical strength. The fixation of the graft therefore has to be complete in order for this period of fragility to come to an end. The mechanical properties of the allografts can be changed by the preservation and storage processes. Lyophilization, massive irradiation of the grafts (in excess of three megarads), or moist heat used for more than 60 min at 120 °C adversely affect the mechanical behavior of the grafts considerably. Cryopreservation, on the other hand, seems to improve the mechanical properties of the allograft, the strength of which is 110–120 % that of fresh bone but the graft, although it is stronger, does in fact become more brittle (in the mechanical sense of the term) and therefore breakable. In the case of articular allografts, the crucial point is preservation of the ligament structures, of the synovial fluid, and of the menisces. The cells in these formations are preserved, as are their architectural and fundamental structure.

After having been reinstated, the vascularization is linked to the revascularization of the bone insertion area. It is inadequate for several months (or years) which means that they have to be doubled with an artificial ligament during this period to avoid excess stresses which would lead to their being stretched or even ruptured. The extent of the immunologically competent tissue (synovial, capsule, etc.) also risks leading to the occurrence of immunological rejection phenomena justifying the use of immunosuppressants (such as Sandimmum) in the event of the hyperproduction of fluid indicating an immune response.

The graft is fixed by osteosynthesis material and the ligaments of the host are refixed onto the graft. The functional results are generally excellent.

The excision is larger and the donor ligaments remain attached to the graft and are refixed onto the host bone or over the ligaments of the host. They have to be protected during the period of revascularization by artificial ligaments.

This applies to:

A total joint graft with its capsule, its synovial membrane, its ligaments, and the fibrocartilages it contains (meniscus or labrum) is indicated in the case of an extensive tumoral lesion in the joint cavity justifying extensive excision in a single piece.

The problems posed are twofold:

The indications for using a prosthesis sheathed with bone from a bone bank are often present and have to be analyzed according to the extent of the loss of musculo-ligament and cutaneous substance which requires tumoral excision or which has been produced by the trauma.