Allograft-prosthesis Composite Research Articles

Fixation of femoral allograft/prosthesis composites after 25%, 50% and 75% resection

The relative linear and angular displacements of proximal femoral reconstructions were compared within six different replacement techniques during ex vivo axial compression, mediolateral bending, and axial torsion in dogs. Each femur was osteotomized at 25%, 50%, or 75% of its length and the proximal portion subsequently replaced using one of six techniques. The reconstruction techniques included various combinations of proximal and distal fixation methods (graft fixation/distal fixation): (1) an allograft/prosthesis composite (APC) press-fit proximally and cemented distally (press-fit/cement); (2) APC cemented proximally and distally (cement/cement); (3) APC cemented proximally and the host bone/graft interface double plated (cement/plates); (4) APC cemented proximally and secured distally with bicortical screws (cement/screws); (5) APC secured proximally and distally with bicortical screws (screws/screws); (6) Segmental proximal femoral replacement cemented into the distal femur without an allograft (no graft/cement). For axial compression and mediolateral bending, the combined resection lengths revealed no differences in linear and angular displacements, respectively, between reconstruction methods. During axial torsion, the cement/cement tech nique allowed larger angular displacements than all but the press-fit/cement technique which had larger displacements than the cement/screws, screws/screws, and no graft/cement groups (p < 0.0001). Overall, the measured implant stability was solid and consistent as evidenced by small amounts of relative displacement and small error values.

Custom-Made Segmental Femoral Replacement Prosthesis in Revision Total Hip Arthroplasty

Patients who present with failed total hip arthroplasty and significant proximal femoral bone loss pose a challenging reconstructive problem. When the integrity of the host proximal femur can be salvaged with cortical strut grafts, conventional long-stem femoral components can be used. If there is massive proximal femoral bone loss, hip salvage can be accomplished with a proximal femoral replacement prosthesis or an allograft-prosthesis composite. Although our early results with a proximal femoral replacement prosthesis were good, long-term results reveal a high rate of dislocation and acetabular component loosening, with an overall survivorship of 73% at 11 years. We have, therefore, limited the use of a proximal femoral replacement prosthesis to the elderly and inactive patient. We are encouraged by the preliminary results of total hip arthroplasty with a second-generation, modular, porous-coated, proximal femoral replacement prosthesis. Longer follow-up is required to determine whether these design modifications improve the results of this type of reconstructive procedure in revision total hip arthroplasty.

The Use of Bone Allografts for Limb Salvage in High-Grade Extremity Osteosarcoma

Limb preservation is increasingly being employed in the local treatment of high-grade extremity osteosarcoma. Bone allografts used to reconstruct the bony defects following tumor resection offer many advantages, including joint reconstruction and incorporation of the graft to the host bone in these relatively young patients. The results of 53 patients 30 years of age or younger were assessed to determine functional outcome. Fresh-frozen allografts were employed as osteoarticular grafts, allograft-arthrodeses, allograft-prosthesis composites, or intercalary grafts. Follow-up intervals averaged 25 months (range, two to 63 months). Life-table analysis showed that the probability of a satisfactory functional result was 73% if local tumor recurrences were excluded. Complications included 16 infections, six fractures, 12 nonunions, and six unstable joints. There were five local recurrences. Eighteen grafts ultimately failed, and in six patients, this resulted in an above-knee amputation. An additional five received a second graft. The functional "end results" of the 38 patients with two or more years of follow-up examinations were 70% satisfactory in those without a local recurrence. There was no statistically significant difference in functional outcome or local or distant relapse in those patients receiving preoperative chemotherapy. The authors conclude that allografts can be used for limb reconstruction in patients with high-grade osteosarcoma who receive aggressive adjuvant chemotherapy. The functional results are comparable to other methods of reconstruction, and once incorporated by the host, offer the advantage of longevity, compared with metallic implants.