1. Aetna considers allograft transplant of the knee (anterior cruciate ligament, osteochondral, and meniscus) medically necessary when selection criteria are met.
   
   Anterior Cruciate Ligament (ACL):
   
   
   1. Members with ACL deficiency who are not candidates for autogenous transplantation (e.g., individuals whose autogenous tissues have been compromised by previous surgery, previous injury), or
   2. Members with pathology such as chronic patellar tendonitis, and hamstring injury, or
   3. Members with any other contra-indications to using their own tissue such as collagen disease or generalized ligamentous laxity.

   Osteochondral:
   
   

   1. Treatment of an isolated, traumatic injury that is full-thickness depth (grade 4, down to and/or including the bone) lesion, preferably surrounded by normal, healthy (non-arthritic) cartilage. The opposing articular surface should be generally free of disease or injury; or
   2. Non-repairable stage 3 or 4 osteochondritis dissecans; or
   3. Avascular necrosis lesions of the femoral condyle; or
   4. Otherwise healthy, active, non-elderly members who have either failed earlier arthroscopic procedures or are not candidates for such procedures because of the size, shape, or location of the lesion.

   Meniscus:
   
   

   1. Members under the age of 45, and
   2. Pre-operative studies (MRI or previous arthroscopy) reveal absence or near-absence of the meniscus, and
   3. Degenerative changes must be absent or minimal, and
   4. Knee must be stable (i.e., intact or reconstructed ACL).

   Aetna considers allograft transplant of the knee experimental and investigational for all other indications.
   

2. Aetna considers osteochondral allograft of talus experimental and investigational because there are unanswered questions regarding the clinical outcomes of this approach when compared with ankle arthrodesis, especially in terms of pain, disability, functionality and durability.

3. Aetna considers osteochondral allograft experimental and investigational for repairing chondral defects/lesions of the elbow and shoulder (e.g., Hill Sachs lesions).

Repair of knee ligaments refers to surgical treatment of acute injuries (ruptures), whereas primary reconstruction usually refers to surgical intervention of ligamentous laxity (chronic insufficiency) several months following an injury.  Revision reconstruction means corrective surgery when the original reconstruction has failed.  The bulk of the literature on ligamentous reconstruction of the knee deals with the primary reconstruction of the anterior cruciate ligament (ACL).  Generally, there are 3 reconstructive methods for managing ACL insufficiency: (i) intra-articular replacements, (ii) extra-articular procedures, and (iii) combined procedures.  The first method is intended to replace the ACL, whereas the second method is intended to tighten the medial or lateral secondary restraints, or both in the third method.  The sources for intra-articular replacements are quadriceps tendon, patellar tendon, hamstring tendons, and iliotibial band or tract.  In particular, the bone-patellar tendon-bone autograft (the central one-third of the patellar tendon and its bony attachments to the patella and tibial tubercle) is the most common operation currently performed for reconstructing the ACL through arthroscopy.

Allograft, also known as allogeneic graft or homograft, is a graft between individuals of the same species, but of dissimilar genotype.  For tendon allografts, cadaver donors are usually used.  The donor tissues most commonly used are the patellar and Achilles tendons.  An allograft may be preserved by freeze-drying or deep-freezing and can be sterilized either by sterile procurement with careful donor screening or by secondary sterilization with gaseous ethylene oxide or gamma irradiation.  It is believed that freeze-drying or deep-freezing renders connective tissue allografts less immunogenic by killing the cells and denaturing surface histocompatibility antigens.  However, while some investigators have claimed that freeze-drying of the allograft does not significantly change the mechanical properties of the grafts compared with deep-freezing; others have reported frequent late failures of freeze-dried allograft tissues.  Fideler and co-workers (1994) concluded that a dose of 30,000 or 40,000 gray (3 or 4 megarad) of gamma radiation is necessary for the inactivation of the DNA of the human immunodeficiency virus in frozen bone-patellar ligament-bone allograft harvested from donors infected with the virus.

Tendon allograft has been used for the repair/reconstruction of the ACL in patients following major knee injury.  The advantages of using these allografts are a more abundant supply of tissue for multiple ligament and revision surgery, a shorter operative time, faster rehabilitation, avoidance of morbidity associated with autograft harvesting, as well as a lower incidence of stiff knee.  On the other hand, the disadvantages in employing allografts are a potentially increased failure rate, a risk of hepatitis or AIDS infection, as well as stimulation of an immune response.

Studies have shown high failure rates with use of allograft for ACL reconstruction (Gorschewsky, et al., 2005; Pritchard, et al., 1995; Roberts, et al., 1991). Prodromos, et al. (2007) performed a meta-analysis of autograft and allograft stability data. Normal stability for all autografts was 72% versus 59% for all allografts (p < 0.01). Abnormal stability was 5% for all autografts versus 14% for all allografts (p < 0.01). Bone-patellar-tendon-bone (BPTB) autograft normal stability was 66% versus 57% for BPTB allografts (p < 0.01). Abnormal BPTB autograft stability was 6% versus 16% for BPTB allograft. Hamstring autograft normal or abnormal stability rates were 77% and 4% and were compared to soft tissue allografts as a group which were 64% and 12% (p < 0.01). The investigators reported that allografts had significantly lower normal stability rates than autografts. The investigators found that allograft abnormal stability rate, which usually represents graft failure, was nearly three times higher than that of autografts. The investigators concluded that autografts are the graft of choice for routine anterior cruciate ligament reconstruction with allografts better reserved for multiple ligament-injured knees where extra tissue may be required.

A metaanalysis of patellar autograft versus allograft for ACL reconstruction found better outcomes with autograft (Krych, et al., 2008). The investigators noted, however, that when irradiated and chemically processed allografts are excluded, the outcomes of autograft and allograft are more similar, but without the irradiation or chemical processing of allografts, there is an increased risk of transmission of infection.

There is inadequate evidence that the use of tendon allograft is equally effective as autograft in the primary reconstruction of anterior cruciate ligament (ACL).  In addition, due to the risk of disease transmission, it should not be used for primary, isolated ACL reconstruction.  Tendon allograft for reconstruction of the ACL should only be employed when an adequate autologous graft is not available for (i) revision surgery (in knees in which a primary reconstruction of the ligament had failed and in which an autograft had already been used) or for (ii) primary reconstruction surgery for combined ligament injuries (ACL and either the posterior cruciate ligament, or medial collateral ligament) when an adequate autologous graft is not available.