**4.3.2 Allogeneic bone grafting**

The limited availability of autologous graft may not be enough to compensate an extensive bone defect and use of homoplastic bone could be indicated (Fig. 5).

Cancellous or structured bone allograft could be used but always have to be considered some rules:


Fig. 5. (a) Cancellous bone allograft, added with antibiotic. (b) Structural bone allograft molded intraoperatively before implanting.

Nevertheless difficulties using bone homologous grafts consisted on:


394 Recent Advances in Arthroplasty

implant subsidence within the first year (Laskin, 1989). Moreover needle biopsy in 9 cases in which the graft had not fragmented, revealed osteocytes in the lacunae in only 4 grafts. In each of four knees, there was a complete radiolucency between the graft and the tibial host bone. The final author's conclusion is to reevaluate the use of modular prostheses in large

Currently there are insufcient clinical data to state with certainty that bone stock restoration with autogenic bone graft will in fact aid future revisions when necessary.

The limited availability of autologous graft may not be enough to compensate an extensive

Cancellous or structured bone allograft could be used but always have to be considered

The graft have to be "protected" by use of an intramedullary stems, able to reduce

Fig. 5. (a) Cancellous bone allograft, added with antibiotic. (b) Structural bone allograft

fragment defects but to continue using bone graft for smaller, circumscribed defects.

Possible reason of autoplastic graft failure have been ipothetised:

 Incomplete coverage of the graft by the tibial component. Extravasation of the cement between graft and host.

bone defect and use of homoplastic bone could be indicated (Fig. 5).

The graft have to be modeled, thus to precisely adapt it to the defect;

 Varus alignment of the leg. Avascular host bed for the graft. Insufficient graft press-fit.

**4.3.2 Allogeneic bone grafting** 

mechanical stress forces.

The graft have to be perfectly stabilized;

molded intraoperatively before implanting.

some rules:

