Structural Bone Allografts Research Articles

Revision total knee arthroplasty by impaction bone grafting.

The presence of bone loss in a failed total knee arthroplasty can present a significant reconstructive challenge. Experience with the technique of using impacted morselized allograft with revision components having fixed stems is presented. Nineteen knees (21 patients) were reconstructed using impacted bone graft alone in 14 knees, bone graft plus methylmethacrylate in five knees (including one knee in which the replacement failed), and in three knees morselized bone graft was used in conjunction with structural bone allograft. Minimum followup ranged from 6 months to 62 months for the patients in the current series. These patients represent a relatively small, but growing portion of this surgeon's population of patients undergoing revision knee arthroplasty. Patients with large defects were selected for the study. Histologic specimens from the one failed knee arthroplasty revealed viable, incorporated bone graft. Excluding the replacement that failed, the average improvement in Knee Society combined knee and function scores was 87 points. The principles of revision and primary total joint arthroplasty are applied for achieving a stable implant. Specific to this technique, solid support of the implant-graft interface, graft-host bone interface, and the use of a tight, supportive stem is imperative. The author's experience provides additional support for the use of bone grafting techniques in patients with large bone defects who are undergoing revision total knee replacement.

Kinetics of cortical bone demineralization: Controlled demineralization—a new method for modifying cortical bone allografts

We investigated the kinetics of hydrochloric acid demineralization of human cortical bone with the objective of developing a method of controlled demineralization for structural bone allografts. It is known that the demineralization of cortical bone is a diffusion rate limited process with a sharp advancing reaction front. The demineralization kinetics of human cortical bone, described as the advance of the reaction front versus immersion time, were determined by measuring extraction of bone mineral in both planar and cylindrical geometries. Mathematical models based on diffusional mass transfer were developed to predict this process. The experimental data fit well with the behavior predicted by the model. The model for planar geometry is applicable to controlled demineralization of cortical bone allografts of irregular shapes such as cortical struts. The model for cylindrical geometry is appropriate when curved surfaces are involved such as in diaphyseal bone allografts. This method of demineralization has direct application to clinical modification of cortical bone allografts to potentially enhance their osteoinductive properties. © 1996 John Wiley & Sons, Inc.

Kinetics of cortical bone demineralization: Controlled demineralization?a new method for modifying cortical bone allografts

We investigated the kinetics of hydrochloric acid demineralization of human cortical bone with the objective of developing a method of controlled demineralization for structural bone allografts. It is known that the demineralization of cortical bone is a diffusion rate limited process with a sharp advancing reaction front. The demineralization kinetics of human cortical bone, described as the advance of the reaction front versus immersion time, were determined by measuring extraction of bone mineral in both planar and cylindrical geometries. Mathematical models based on diffusional mass transfer were developed to predict this process. The experimental data fit well with the behavior predicted by the model. The model for planar geometry is applicable to controlled demineralization of cortical bone allografts of irregular shapes such as cortical struts. The model for cylindrical geometry is appropriate when curved surfaces are involved such as in diaphyseal bone allografts. This method of demineralization has direct application to clinical modification of cortical bone allografts to potentially enhance their osteoinductive properties.

Treatment of type III acetabular deficiencies in revision total hip arthroplasty without structural bone—graft

The use of structural bone allografts has been advocated for the reconstruction of type III acetabular defects, but the results reported for this method have shown revision rates from 20 to 30% and failure rates averaging 50% at short-, to intermediate-term follow-up periods. A prospective study was undertaken to determine the results of reconstructing type III defects without structural allograft and to compare the results using spherical components with the results using eccentric components. Quantitative inclusion criteria were developed and applied to all hips undergoing revision arthroplasty between 1987 and 1991. Twenty-one hips (20 patients) were identified and included in this study. An evaluation protocol including radiographs, and for defects greater than 30 mm, computed tomography scans and three-dimensional models, was used. At an average follow-up period of 46 months, 19 hips (18 patients) were evaluated. Hip scores of these patients improved from 46 to 75. The location of the hip center was improved to a greater degree in those hips with revised to eccentric components, but implant stability was poor. Overall, the mechanical failure rate was 26%, the clinical failure rate was 16%, and the revision rate was 11%. These results compare favorably with the results of reconstruction using structural graft at the same length of follow-up time. Good results can be achieved by reconstructing type III defects without structural allograft if a cementless spherical component can be placed in stable position on host—bone.

Failures after revision hip arthroplasties with threaded cups and structural bone allografts. Loosening of 13/18 cases after 1-4 years.

Uncemented threaded, smooth cup acetabular components and structural deep-frozen bone allografts harvested from femoral heads during arthroplasties were used for reconstruction of the acetabulum in 18 revision hip arthroplasties. Autogenous bone grafts were also used in every case. The mean follow-up time was 2.5 (1-4) years. Loosening of the prosthetic component occurred in 13 cases. In 8 cases revision of the acetabular component has already been performed, and 5 cases remain to be reoperated. The use of uncemented, threaded cups in combination with reconstruction of bone defects with structural allografts cannot be recommended in acetabular revisions.

Vascular Complications of Orthopaedic Surgery

The role of allograft tissue, including bone, cartilage and soft tissue, has become more defined in lower extremity reconstructive surgery. Revision arthroplasty of the hip commonly requires restoration of bone stock using allograft bone. Morcellized bone is used for contained defects on both the acetabular and femoral sides. Structural allograft bone is used for uncontained or segmental defects, and the results are less predictable; therefore, its use is more controversial. Alternatives include the jumbo cup, oblong cup, and high hip center on the pelvic side and tumor prostheses or distal fixation on the femoral side. These alternatives do not, however, restore bone stock, thus making further surgery more difficult. Structural grafts allow attachment of bone and soft tissue and restoration of the correct anatomy and have been shown to restore bone stock for further surgery, particularly on the acetabular side. Improvements in the quality and safety of banked bone and the development of surgical techniques have enhanced the results of structural allograft bone grafting. Restoring bone stock in revision arthroplasty of the hip is an accepted standard for the patient likely to undergo further surgery. Continuing to develop technologies that will facilitate the use of allograft tissue is imperative.