Biomechanics of Allografts

Abstract

The advantages of using autograft in defects less than 6 cm even in areas of high mechanical demand have been addressed elsewhere in this book (Chapter on Intercalary Reconstruction). If the defect exceeds what is possible to compensate with autograft it often becomes necessary to consider the use of allogeneic tissue. Furthermore, complications associated with autograft occur not infrequently and include blood loss and hematoma at the procurement site necessitating transfusion, infection, injury to the lateral cutaneous nerve of the thigh, fracture of the remaining iliac wing, hernia, and persistent pain and cosmetic deformity. Alternatively, allograft is associated with no morbidity with procurement, decreased operative time, allows modifying the bone graft to fit the deficiency anatomically, and theoretically unlimited supply. As such, transplant bone and soft tissue have become viable alternatives in the reconstruction of the multiply revised arthroplasty patient, after tumor resection, spinal surgery and in complex soft tissue deficiencies such as ligament reconstruction of the knee and rotator cuff repair of the shoulder. The long-term success of musculoskeletal transplantation, however, depends on the incorporation of the allograft to the host, whether it be osseous or soft tissue and avoidance of complications. Both of these factors are dependent on the biology and biomechanics of the reconstruction and are not mutually exclusive. Implications of the former to allograft success is thoroughly discussed by Dr. Hans Burchardt in a previous chapter.