Multiple graft choices exist for surgical reconstruction of the anterior cruciate ligament. No single graft choice has been demonstrated to be superior, and graft choice should be individualized for each patient.
Historically, autologous bone-patellar tendon-bone has been the most commonly used graft. The disadvantages of autologous graft include donor site morbidity, the potential for stiffness, and anterior knee pain.
The use of allograft tissue for anterior cruciate ligament reconstruction has gained popularity for multiple reasons. These include less surgical morbidity, shorter operative time, easier early postoperative recovery, improved cosmesis, and the availability of larger and multiple grafts for complex or revision surgeries. The risks of allograft tissue include disease transmission, immune reaction, slower incorporation, and higher failure rate.
Despite the fact that postoperative infection following any anterior cruciate ligament reconstruction is a serious complication, there is a paucity of reports concerning the risk of infection related to the choice of graft. Fortunately, the transmission of viral or bacterial infection by allograft tissue has been fairly rare.
There have been one reported case of HIV transmission and two cases of hepatitis-C transmission by bone-patellar tendon-bone allografts1. The risk of bacterial infection transmitted through the use of allograft tissue received national attention when fourteen cases of patients with an allograft-associated Clostridium infection, including one death, were reported over a four-year period from 1998 to 2002. All fourteen grafts had been processed by a single tissue bank2.
The article entitled "Allograft Compared with Autograft Infection Rates in Primary Anterior Cruciate Ligament Reconstruction," by Greenberg et al., addresses a very timely question. Historically, the prevalence of septic arthritis after anterior cruciate ligament surgery has been reported to range from 0.2% to 4.0%3. Synthetic grafts and hamstring grafts have been more commonly involved. With the increased use of allograft tissue and at least one known cluster of allograft-associated bacterial infections, it is important to determine if allograft use in anterior cruciate ligament surgery exposes a patient to a greater risk of septic arthritis. Greenberg et al.’s study is a Level-II combined prospective and retrospective multicenter cohort study of 861 patients undergoing primary anterior cruciate ligament surgery with use of autograft or allograft tissue.
The allografts were obtained from a single tissue bank that used aseptic processing and low dose irradiation. A single dose of antibiotics was given intravenously preoperatively, and no drains were used postoperatively. No deep infection was identified in any of the 861 patients. Statistical analysis of the fact that there was no case of septic arthritis in either group indicated a 95% confidence interval of 0% to 0.57% for the allograft group and 0% to 1.66% for the autograft group. The overall rate of superficial infections was 2.32%. There was no statistical difference between the two groups. The results of this study are reassuring for orthopaedic surgeons using allograft tissue obtained from an accredited tissue bank. They are also consistent with those of a recent, similar, well-powered study by Barker et al.4
The risk of an immune reaction leading to allograft failure after anterior cruciate ligament reconstruction appears to be extremely low, and, to my knowledge, no report documenting this potential complication has been published in the literature.
Long-term follow-up and future studies will even better define the role of allografts in anterior cruciate ligament surgery and the potential problems that may be associated with allograft use.