The biology of bone grafting.

Allograft bone continues to play an important role in revision hip and knee arthroplasty with well documented clinical success. A basic understanding of allograft biology and immunology is important in order to optimize outcome. The importance of the interaction of immunologic factors with the biologic processes involved in bone graft incorporation has yet to be fully understood.

Biology of allografting.

Allograft bone continues to play an important role in revision hip and knee arthroplasty. A basic understanding of allograft biology and immunology is important in order to increase the success of allografting. Although the literature has a wealth of knowledge on the subject there are still many unknowns.

The immune response: the afferent arm.

The key to understanding afferent immunity is the mechanism of activation of T lymphocytes by specialized antigen presenting cells, which bind antigenic peptide to Class II major histocompatibility molecules, and stimulate T cells via Signal 1 (antigen) and Signal 2 (costimulation). The best studied costimulatory pathway is the interaction of B7-1 or B7-2 ligand molecules on antigen presenting cells with CD28 or CTLA-4 receptors on T cells. T cell signaling occurs through the T cell receptor-CD3 complex and is augmented by cosignaling via CD4, CD8, and CD45.

Fresh osteochondral allografts for advanced giant cell tumors at the knee.

Sixteen patients with advanced giant cell tumors presenting at the knee were treated with complete tumor resection and reconstruction using fresh osteochondral allografts. All patients had one or more of the following indications for tumor resection (as opposed to curettage): tumor recurrence, pathologic fracture, or destruction of the subchondral bone plate. At the 3-15-year follow-up period (mean, 9 years), two grafts have been revised to second fresh grafts because of fracture and one graft has been converted to an allograft-implant composite reconstruction.