**4.3.1 Autologous bone grafting**

In primary TKA, the resected femoral condyles or tibial plateau sometimes can be used as a source of autograft for tibial defects; morcelized bone obtained from the tibia and femoral resections can be used as autograft in contained defects.

Its use have been advocated by various authors (Dorr et al., 1986; Scuderi et al., 1989), constituting a viable option due to excellent osteoinductive, osteoconductive and osteogenic properties (Fig. 4).

Fig. 4. An oblique planar cancellous surface is created on the recipient side, and coaptation of proximal tibia autograft surface is ensured to this recipient bed by screw or wire fixation. (courtesy of Dr. E.A. Martucci)

Nevertheless Laskin in a series of 26 patients with severe tibial bone loss treated by TKA using autogenic bone graft into the defect, observed 4 cases of grafts fragmentation with

Management of Bone Loss in Primary and Revision Knee Replacement Surgery 395

Structural bone allograft offer**s** numerous advantages, including biocompatibility, bone stock restoration and potential for ligaments reattachment. Regarding their versatility it is possible to treat a wide range of bone deficiency allowing the surgeon to shape the allograft to fit the bone defect and avoid unnecessary removal of host bone. Finally allograft is

The goals of structural allograft reconstruction are to maximize the stability of the grafthost bone contact and provide a stable platform for fixation of the implant. The first step is to remove all the nonviable bone and soft tissue from in and around the defect, the presence of viable bone is absolutely necessary to maximize the likelihood of graft incorporation. Conversion of the oblique peripheral defects into rectangular space with vertical and horizontal surfaces has been demonstrate to improve stability for components fixation. The angular patterns have also a biological advantage since it allows improving the contact area of the host-graft construct maximizing the probability of graft incorporation. Regarding the choice of the graft it is important to shape the allograft similarly in order to fit the defect precisely. Graft fixation too is an important step to be taken in consideration: mainly used are partially or fully threaded cancellous

In the literature there are various papers reporting about the use of allograft to restore bone defect during revision knee arthroplasty, especially for uncontained defects. In some cases with circumferential segmental bone defect of tibial plateau, have been demonstrated about 25% of allograft failure (De Long et al., 2007; Engh & Ammeen, 2007). Engh & Ammeen, whose have reviewed the results of 49 knees with severe tibial bone loss, found only four cases of failure for reasons not-directly related to collapse or resorption of the graft; most of patients had contained defect and ten presented an uncontained deficiency of which only four cases were restored with full segment allograft. Recently Backstein D, et al have reported 85.2% of success rate at an average follow-up of 5.4 years in a series of 68 revision that required a structural allograft for the treatment of

Even if a variability of result are present in the literature, due to the significant difference of the lesion treated, all authors agree on affirm that the use of a intramedullary stem with a sufficient length to engage diaphyseal bone is mandatory to decrease axial and shear loads to the structural allograft in accordance with previously data emerging from the laboratory

We have experienced reconstruction with massive structural allograft during primary total knee replacement for severe segmental medial post-traumatic tibial plateau defect in arthritic knee (Tigani et al., 2011); neither acute nor chronic complications were observed, and radiological examination referred no signs of prosthetic loosening or secondary

relatively cost-effective if compared to the high cost of custom-made implants.

Nevertheless difficulties using bone homologous grafts consisted on:

Need of a bone bank support;

**4.3.3 Structural massive bone allograft** 

uncontained defect (Backstein et al., 2006).

resorption, with good grafting integration to host bone (Fig. 6).

(Mounasamy et al, 2006).

 Increased risk of infection; Disease transmission.

Grafts resorbtion;

screws.

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

Possible reason of autoplastic graft failure have been ipothetised:


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.
