Review Question - QID 4626

Of the options listed, freeze dried cancellous allograft has the least potential to elicit an immune response. Remember, all allograft tissue has more of an immune response generating capability than autograft tissue, which has the least of any of these materials.

All allograft materials carry immunogenic properties, which decrease as the material is processed via the various sterilizing, freezing, or drying process(es). As the processing increases, the mechanical characteristics of the graft tends to decrease.

Ahlmann et al. compared the complications associated with harvesting iliac crest bone graft from the anterior crest and posterior crest. They found the rates of both minor complications (p = 0.006) and all complications (p = 0.004) were significantly higher after the anterior harvest procedures than they were after the posterior procedures. They recommend that iliac crest bone graft be harvested posteriorly whenever possible.

Incorrect Answers:
Answer 1: Most bone and soft tissue allografts undergo irradiation to remove bacteria or other infectious agents, but this does not prevent an immune response in itself.
Answer 2: Fresh frozen allografts have more immunogenic potential than freeze dried, but less than fresh materials. Fresh allograft is not typically utilized, as the processing of allograft (bone or soft tissue) provides the safety of minimizing infectious disease transmission.
Answer 3: Fresh frozen allografts have more immunogenic potential than freeze dried, but less than fresh materials. Thus fresh Achilles tendon allograft has the highest immunogenicity.
Answer 4: Fresh Achilles tendon allograft will elicit the greatest immunogenic response.