Health Problem: The anterior cruciate ligament (ACL) is 1 of 4 major ligaments in the knee joint that maintain stability of the joint. Rupture of the ACL is a common knee injury, with > 200,000 ruptures occurring yearly in the United States. Most ACL injuries are complete or near-complete tears resulting in substantial joint instability, and approximately half of such injuries occur along with damage to the meniscus, articular cartilage, or other ligaments. An individual with a partially torn ACL can recover without surgery but may still have joint instability. A complete ACL rupture is treated surgically to reconstruct the ligament.

Technology Description: The choice of an autograft or allograft for ACL reconstruction depends on several factors, including the patient’s preference, age, and activity level; tissue availability; and the existence of associated ligamentous injuries. Tendon allografts for ACL reconstruction are purchased from tissue banks that provide recovery, processing, and distribution of allograft tissue. Most tissue banks use chemical soaking with a solution of antibiotics and antiseptics to help reduce contamination, although this procedure may be effective only against surface contaminants. To remove remaining microorganisms, secondary sterilization may be performed using chemical sterilants or gamma irradiation. ACL reconstruction is performed arthroscopically. After the torn ACL stump is removed, the tendon graft is secured into tunnels drilled into the tibia and femur. Over time, the implanted tendon undergoes a functional adaption and a continuous postoperative remodeling process, resulting in a tissue that resembles the structural properties of the native ACL.

Controversy: There is controversy regarding which type of graft material to use for reconstruction of the ACL—allograft or autograft. Use of an autograft tendon is associated with donor site morbidity, longer surgical times, and the risk of unsuitability of harvested graft material (e.g., insufficient graft size, poor quality). While allografts overcome these limitations, they carry risks of infectious agent transmission, immune response, and delayed incorporation (Paschos and Howell, 2016). Irradiation of allograft tissue reduces the risk of infectious agent transmission; however, irradiation damages tissue and may reduce the allograft’s effectiveness for ACL reconstruction.

Key Questions:

  • Are irradiated allografts effective in repairing knee function following ACL reconstruction?
  • How do irradiated tendon allografts compare with autografts and nonirradiated allografts regarding knee function following ACL reconstruction?
  • Are irradiated tendon allografts safe?
  • Have definitive patient selection criteria been identified for the use of irradiated allografts?

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