According to the Centers for Disease Control, there have been 63 recorded cases of disease transmission as a result of allograft transplant over a 10-year period from the mid-1990s to the mid-2000s. Because approximately 1.5 million allograft implants are performed each year, there is approximately a risk of 1 in 120,000 chance of infection as a result of disease transmission.
The risk of HIV infection as a result of allograft tissue transplant has been estimated to be one in a million. That is not to imply that it can't happen, but the risk of other severe complications from surgery is much more likely than the risk of disease transmission.
Who Needs Donor Tissue?Many orthopedic surgical procedures require that a damaged part of the body is surgically reconstructed using healthy tissues. If you don't have available tissues, or if you don't want to undergo the surgery necessary to obtain necessary tissue, one option is to use donated body parts from a cadaver donor. Donated tissue includes tendons, ligaments, bone and cartilage.
Surgical procedures that may be done using donor tissues include:
How Donor Tissue Is ObtainedInfection transmission could be the result of a disease the donor had in his or her body, or contamination of the tissue during processing. Therefore, efforts are made to ensure that the donor did not have a potentially transmissible disease, and that the donated tissues are handled in a manner that minimizes the chance of contamination.
When donor tissues are collected for possible transplant, significant screening takes place to ensure safety of these tissues. When a possible donor is identified, a screening of the donor is performed to determine the cause of death, possible high-risk behaviors that may make the donor tissue less safe (for example, drug use, etc.), and the donor's medical history. Blood tests are done to evaluate for infection. Specifically, donors are evaluated for HIV, hepatitis B & C, transmissible spongiform encephalopathies (for example, "mad cow disease"), and syphilis, among other diseases.
Allograft tissues that are determined to be appropriate for transplant are processed in clean room environments. They receive sterility testing at the time the tissue is obtained, during its processing, and prior to its release from the processing facility. The processing phase of allograft tissue preparation includes sterilization of the tissues.
When the tissue is processed for orthopedic procedures, cellular components of the tissue (including blood cells) are removed to prevent the chance of tissue rejection. During this processing, sterilization also takes place. Sterilization must not be so severe as to weaken the tissues, but sufficient to prevent bacterial or viral contamination.
Tissues that have been prepared are then sent to hospitals for implantation. There are different ways to store tissues, but most are frozen at -80 degrees centigrade. The tissues have an expiration date depending on the type of tissue and the type of storage.
Questions to Ask Your DoctorYour doctor should know exactly where the tissue came from; this recommendation has been made by the American Academy of Orthopaedic Surgeons.
Ask your doctor what tissue bank is supplying the graft, and why that tissue bank has been selected. Not all tissue banks are created equal, and some have more stringent screening policies when selecting which donors are suitable for their distribution. If your doctor is unaware of where your graft is coming from, he or she will not know how strict the criteria used to select the graft has been.
There have been reports in the news of tissue banks mishandling tissues or improperly obtaining tissues. Your doctor should screen tissue banks to ensure that the grafts being supplied are of high quality and optimal safety. Some tissue banks have websites for patients to learn more about their techniques for obtaining and processing tissues. Your doctor can supply you with information about where your graft is coming from.
"Allograft-Associated Bacterial Infections - United States, 2002" Centers for Disease Control. March 15, 2002 / 51(10);207-210.
Gocke, D "Tissue Donor Selection and Safety" Orthop Clin: June 2005; Vol 435, p 17-21