Allografts are a valuable treatment option for complicated orthopedic cases done on an outpatient basis, but questions regarding their safety persist, fueled by a few well-publicized infections attributed to contaminated grafts. Grafts that aren't properly processed can cause lethal or debilitating infections in recipient patients, but the experts we talked to say allografts are safe when an accredited tissue bank supplies them and you follow the appropriate surgical techniques. Here's what you can do to limit infection during allograft procedures.

1 Educate your surgeons and staff on tissue processing methods
Do you know your tissue bank's procedures for procuring, processing and storing allograft tissue? A recent study on allograft-associated infections in patients who underwent musculoskeletal allograft implantation at an outpatient surgery center found that "most of [the surgery center's] surgeons and personnel were unaware of the different methods used for processing allograft tissues."[1]

One source of confusion: the common misperception that all processed allograft tissue is sterile when it arrives at your facility. Improper labeling by tissue banks may be another. In the past, tissue banks could label their allograft "sterile" without having a validated sterilization process. The reality is that most tissue banks aseptically process tissue without terminal sterilization because these methods (such as high-dose gamma irradiation and ethylene oxide sterilization) have traditionally rendered the tissue unusable. Although the FDA has now instituted controls to prevent improper labeling of non-sterile tissue, the misleading notion of allograft sterility persists.

Tissues that have not undergone a sterilization process could contain spores produced by anaerobic microorganisms, says Lennox K. Archibald, MD, the hospital epidemiologist at the University of Florida and medical director at Regeneration Technologies. As an example, Dr. Archibald points to a spore-forming bacterium, Clostridium sordellii, that caused an allograft-associated infection in an otherwise healthy 23-year-old man in 2001. Validated processes such as low-temperature chemical sterilization or high-dose gamma irradiation kill spores, but antimicrobials do not. Aseptic processing does not remove viruses, bacteria, or spores that originate in the cadaver. The only definitive way to remove these types of organisms is through a sterilization process.

If your facility regularly deals with allograft implantations, conduct in-services with your surgical staff to educate them on the difference between aseptically processed tissue and sterilized tissue. Two references you might consult:

• Joyce MJ. Safety and FDA regulations for musculoskeletal allografts: perspective of an orthopaedic surgeon. Clinical Orthopedics and Related Research. 2005 Jun;(435):22-30.
• Barbour SA, King W. The safe and effective use of allograft tissue - an update. American Journal of Sports Medicine. 2003 Sep-Oct;31(5):791-7.

2 Carefully select your tissue bank
Contaminated allografts originating from the donor cause the most serious of allograft-related infections. When donor tissue possesses in situ contaminants, you must trust that your tissue processor has taken every measure to ensure the tissue is free of contaminants when it arrives at your facility.

After the death of a 23-year-old man from allograft-associated infection in 2001, the CDC conducted an epidemiological investigation revealing 13 other infections that could be traced back to contaminated allograft distributed by a single tissue bank.[2] You can improve the likelihood that you'll receive clean, sterile tissue by taking these two steps:

• Choose an accredited tissue bank. Of the 166 tissue banks registered with the FDA in May 2004, less than half were accredited by the American Association of Tissue Banks. Choose an AATB-accredited tissue bank to demonstrate adherence to strict donor eligibility screening and processing techniques, say experts. The AATB requires that its members perform full screening that meets FDA requirements. Also keep in mind that many states have no licensure requirement for tissue banks. Tissue banks that lack accreditation and licensure are not required to comply with external quality requirements beyond donor screening for HIV and hepatitis.
• Select a tissue bank that has a validated sterilization process. Many proprietary sterilization and processing methods exist to prevent soft tissue allograft contamination. Examples include a low-temperature chemical sterilization technique called Biocleanse (Regeneration Technologies, Inc.), a sterilization method that uses 50kGy gamma irradiation with radiation protectants called the Clearant process (Clearant, Inc.) and a terminal sterilization technique called the Tutoplast process (Tutogen Medical, Inc.).

3 Keep meticulous records of your tissue
Dennis Auzenne, director of perioperative services at Texas Orthopedic Hospital, recommends keeping an accurate tissue log that documents the tissue from the moment it arrives at your facility to the moment it is implanted.

The log should contain arrival time at the facility, tissue type, serial number, lot number, donor number and tissue bank. Update this log once you've implanted the allograft with the patient's name, date, surgeon and procedure performed. Send this information to the tissue bank. In the event of a problem with a donor, this log lets both the hospital and the tissue bank trace which patients received transplants from which donor.

4 Don't unnecessarily handle sterile
tissue As a precautionary measure, some surgeons and facilities routinely perform pre-implantation cultures of allograft, or suspend the allograft in an antibiotic solution. While these measures would appear to reduce the risk of infection for the tissue recipient, experts issue a word of caution.

"Cultures can produce false positives and false negatives because there is no standardized way to obtain sample of the tissue," says Marion Kainer, MD, an infectious disease physician with the Tennessee Department of Health and lead investigator in the 2004 study on clostridium infection of musculoskeletal tissue allograft. "There is also the question of what you are going to do with the information if the lab returns a positive result of contamination after the tissue implantation has taken place."

To obtain a culture, a swab sample is usually taken before implantation and then sent to a lab. The surgeon proceeds with the implantation of the tissue without the culture lab results, which are usually returned about three days after the procedure. At that time, if there is a positive result of contamination, the question arises whether the tissue implant should be removed or if a strong course of antibiotics is sufficient. Subjecting patients to a six- to eight-week course of antibiotics as a prophylactic measure is not without risk, especially when based on results that can be easily skewed by the way in which the culture is obtained. Performing unnecessary cultures can also be very costly and wasteful, since no study exists to show that the cultures can help reduce the risk of infection.

As for suspending the tissue in an antibiotic solution before implantation in the hopes of removing surface contaminants, Dr. Kainer offers this advice: "If you are sufficiently concerned that the tissue is not sterile that you would want to put it in an antibiotic solution prior to implantation, don't use it. Instead, use tissue that you know has been sterilized by a validated method."

5 Always use good sterile practice
Good sterile practice is critical in the prevention of any surgical site infection. The simple of act of a surgeon turning away and putting his back to a sterile field can lead to the introduction of bacterial contaminants to the surgical site. All personnel near the sterile surgical field, including anesthetists, should strictly adhere to the rules of asepsis.

With regard to allograft, surgical technicians and OR nurses should take care not open the tissue or deliver it to the sterile field until the surgeon is ready to start the implantation.

6 Recognize symptoms of allograft-associated infection and report findings
Detailed reports of specific cases of Clostridium sordellii and streptococcus pyogenes infection attributable to contaminated allograft reveal that patients experience symptoms of high fever, pain, erythema, and chills five days to 10 days after surgery. If you suspect allograft infection, here's what to do:

• Remove the contaminated allograft from the infected area;
• take cultures of the potentially infected allograft or wound aspirate to isolate the contaminant; and
• submit an incident report to the tissue bank, appropriate state regulatory agency and the CDC Division of Health Care Quality Promotion: (800) 893-0485.

Additionally, as part of the good tissue practices rule implemented earlier this year, the FDA now requires tissue banks to report all adverse reactions involving a communicable disease if it necessitates medical or surgical intervention within 15 days of receipt of original information.

Rare but catastrophic
The AATB estimates that about 1 million allografts were distributed in 2002. While the incidence of allograft-related infection is very low, the consequences of such infection are life threatening.

Four cases of infection following ACL reconstruction performed in surgery centers received national attention in 2000. Two cases of septic arthritis related to a Texas tissue bank indicated that the allografts were the source of the infection despite no apparent lapses in tissue processing. Two cases of septic arthritis related to a Florida tissue bank were linked to allografts from a common donor that were released inadvertently before standard terminal sterilization procedures were conducted.

References
1. Crawford C, Kainer M, Jernigan D, Banerjee S, Friedman C, Ahmed F, Archibald LK. Investigation of postoperative allograft-associated infections in patients who underwent musculoskeletal allograft implantation. Clinical Infectious Diseases. 2005 Jul 15;41(2):195-200.
2. Kainer MA, Linden JV, Whaley DN, Holmes HT, Jarvis WR, Jernigan DB, Archibald LK. Clostridium infections associated with musculoskeletal-tissue allografts. New England Journal of Medicine. 2004 Jun 17;350(25):2564-71.