Large Allografts Research Articles

Reconstruction of the Extruded Talus with Large Allograft Interfaces: A Report of 3 Cases

Although replant of the extruded talus would be preferable at the time of initial management, some patients present with a talus that had not been recovered. A series of 3 cases of the extruded talus that were reconstructed with large allograft interfaces are presented. Two of the cases had femoral head allografts and the other used morcellized cancellous allograft. Several orthobiologic substances were used in various proportions for each case. All 3 resulted in a solid union with minimal shortening of the extremity. 4.

Effect of perforation plus condensed bone marrow on healing of structural bone allografts in rabbits

Objective To observe the efficacy of repairing and reconstructing large femoral defects in rabbits with large perforated allografts of cortical bone plus condensed host bone marrow. Methods Thirty-six Japanese rabbits were randomly divided into 3 equal groups.A bone defect of 3 cm wag created by surgical resection of the middle region of left femar in each animal.The defect was filled with a large fragment of cortical bone allograft and cancellous bone powder in group A,with a perforated large fragment of cortical bone allograft and canceHous bone powder in group B,and with a perforated large fragment of cortical bone allograft and cancellous boHe powder mixed with condensed host bone marrow in group C.Three months after transplantation.bone samples were harvested for histological analysis,radiological examination,bone density measure and biomechanical test. Resuits Radiological examination:In group A,little callus was foand in the allograft except some callus in the donor-host interface.Much callus wag found in groups B and C,and callus extended significantly wider in group C.Histological analysis:Allografts at the donor-host interface were completely absorbed and replaced by much well-remodeling callus in all groups.At the transverse section,little endosteal callus was seen in group A and some endosteal and periosteal callus was seen in group B which was separated by fibrous tissue. In group C,much endosteal and periosteal callus formed in the bone graft,and a great deal of osteoblasts filled the medullary cavity.Periosteal callus in group C was found to have transformed into cancellous architecture and been separated by fibrous tissue. Bone density measure:The density in group C was greater than that in groups A and B and contralateral normal femur(P＜0.05).Biomechanical test:No significant difference wag found in the maximum three-point bending load among groups A,B and C(P＞0.05),but the load in all groups wag lower than that of the contralateral normal femur(P＜0.05). Conclusion Perforation plus condensed boue marrow can promote early ineorporation of large fragments of bone allograft and improve new bone formation. Key words: Bone allograft; Defect; Bone marrow; Perforation

Pasteurized autograft‐prosthesis composite for reconstruction of proximal tibia in 13 sarcoma patients.

The purpose of this study is to ascertain the survival of the pasteurized autograft-prosthesis composite and functional outcome of this procedure, and to evaluate the complications including nonunion, infection, loosening, bony resorption, and fracture. We retrospectively reviewed 13 proximal tibial sarcoma patients who underwent tibia reconstructions with using a pasteurized autograft-prosthesis between 1993 and 2003. Four patients underwent removal of the composite with a minimum follow-up of 11 months (average: 43 months, range: 11-75 months). The survival rate of the 13 composites, as calculated by the Kaplan-Meier method, was 76.9% at 5 years. The primary cause of removing the composite was infection in three patients and loosening in one patient. The average MSTS functional score of 11 patients was 23.6 +/- 3.3 (79%). Nonunion was identified in four patients, while infection developed in three patients. Loosening of the stem and resorption of the pasteurized bone was detected in one case each. No patient developed fracture of autograft. Our data suggest that the pasteurized autograft-prosthesis has comparable functional outcome and complication rates as other methods, such as endoprosthesis and allograft-prosthetic composite and it offers a reconstructive option for surgeons who do not have access to large allograft banks.

Antimicrobial susceptibility of coagulase‐negative staphylococci on tissue allografts and isolates from orthopedic patients

Allograft infection occurs at a rate not different from that of similar procedures with large allografts or sterilized prosthetic devices and is usually caused by coagulase-negative staphylococci (CNS). CNS are feared for their limited antimicrobial susceptibility. We aimed at investigating this risk. CNS were isolated from 260 of 1461 allograft tissue grafts and compared with 384 consecutive clinical isolates from a general orthopedic population (258 patients). The CNS were identified and examined for their susceptibility to nine antibiotics used in routine practice. Staphylococcus epidermidis was the most commonly identified (35%) and the most resistant species of the allograft isolates. Comparing the overall antibiotic susceptibility patterns, clinical pathogens were significantly more resistant to six of the nine antibiotics (p < 0.01), namely penicillin, oxacillin, erythromycin, clindamycin, ofloxacin, and gentamicin. In conclusion, massive allograft infection is a well-known life-threatening surgical risk. However, we did demonstrate that allograft-related in contrast to orthopedic clinics-related CNS, are susceptible to commonly used first and second line antibiotics.

Effect of End-Cutting Intramedullary Reamers on Host-Allograft Contact Area

Use of large allografts in the diaphyseal region can be complicated by nonunion of the host bone to the allograft. Increasing the contact area at this interface can help prevent this from happening. This study investigated the resulting contact area with use of end-cutting reamers to prepare the interface of host and allograft bone in the daiphyseal region, as compared with hand preparation using a sagittal saw. Using a sawbone model, it was demonstrated that the end-cutting reamers produced a significantly greater contact area, compared with hand-cutting techniques.

THE DOVETAIL CONFIGURATION: A BIOMECHANICAL ANALYSIS OF A V-SHAPED OSTEOTOMY DOCKING SITE

Large allograft bones are commonly used in limb salvage procedures for the reconstruction of bone defects after resection of a bone tumor. A V-shaped osteotomy may perform better than the traditional transverse osteotomy as it increases the stability of the docking site and increases the contact area between an allograft and the host cortex. The aim of this study is to investigate the biomechanical properties of a V-shaped docking site of different angles. orcine femurs with 45°, 60° or 90° V-shaped osteotomy were first tested with 1000 N compression, followed by 2 and 5 Nm torque. The torsional stiffness of the 45° specimen group at 5 Nm torque was significantly higher (P&lt;0.05) than the 90° group. Therefore, our results show that 45° V-shaped osteotomy is found to be the most stable docking angle.

Development of heating method by microwave for sterilization of bone allografts

The purpose of this study was to develop a disinfection method using a microwave apparatus to treat large bone allografts. Heating of a bone allograft is an effective method for the disinfection of bacteria or inactivation of viruses. However, the size of the bone we can treat is limited, and following the popular method of using a bathtub is a lengthy process. The experimental system described here was designed using a microwave oven, an optical-fiber thermometer, and a power regulator. Large and small specimens, a femoral head, and a metatarsal were harvested from a bovine femur. The influence of size and the electrical or thermal characteristics of the specimens were assessed regarding temperature distribution after microwave irradiation. The effects of humidity or hot-air supply were also assessed. The average temperature of the bovine femoral head became 80°C throughout the 15 min of microwave irradiation, although the temperature in the metatarsal did not attain uniformity. Microwave irradiation with a hot-air supply realized a uniform distribution of temperature at 83.0° ± 0.4°C in the metatarsal within 15 min. Use of microwave irradiation enables quick heating for disinfection of large allograft bones when a hot-air supply was used as well.

Fixation of large segment femoral allografts using plates augmented with cerclage wires.

Results using plates augmented with cerclage wires to stabilize eight large segment femoral allografts are described. Two patients had plates augmented with cerclage wires placed at the time of tumor resection, and six patients had plates augmented with cerclage fixation placed to manage allograft nonunions or fractures. These internal fixation techniques spanned 10 osteotomy sites: two metaphyseal and eight diaphyseal. The goal of operations that involved internal fixation with plates augmented by cerclage fixation was to obtain osseous union. Osseous union was achieved at both metaphyseal osteotomy sites and at one of the diaphyseal osteotomy sites. Internal fixation of large segment allografts with plates that are augmented with cerclage wires yield poor results when osseous union is the goal of treatment.

Bone Graft Materials

Autograft, allograft, and synthetic bone graft substitute materials play an important role in reconstructive orthopaedic surgery, and understanding the biologic effects of these materials is necessary for optimum use. Although vascularized and cancellous autograft show optimum skeletal incorporation, host morbidity limits autograft availability. Experimental studies have confirmed an immune response to allograft bone, but the clinical significance of this response in humans still is unclear. Small amounts of cancellous allograft in humans usually are remodeled completely; large allografts become incorporated by limited, surface intramembranous bone formation suggesting that these graft are primarily osteoconductive. Several synthetic skeletal substitute materials also are osteoconductive, and may show remodeling characteristics similar to allograft. Demineralized bone matrix and some isolated or synthetic proteins can induce endochondral bone formation, and therefore are osteoinductive. The extent and distribution of remodeling of bone graft materials are influenced by many factors, including the quality of the host site and the local mechanical environment (strain). Graft materials are likely to become more specialized for use in specific clinical applications, and composite preparations may soon provide bone graft materials with efficacy that equals or exceeds that of autogenous grafts.

The procurement team as a factor of bone allograft contamination.

We studied the effect of the procurement team on the risk of contamination in 270 large bone allografts retrieved from 53 non-living donors under strictly aseptic conditions.The overall contamination rate was 8.1%. When the procurement team was constituted by three or less members the contamination rate was 5.6%, while if there were four or more members the rate was 12.9%; this difference was significant in the statistical analysis.We conclude that a procurement team constituted by three or less trained members is a determinant factor in decreasing the bacterial contamination rate of bone allografts.

Immune responses to osteoarticular allografts of the knee--cytokine studies.

Immunological behaviour in correlation with bone allograft survival was studied in peripheral blood and synovial fluid from seven patients who had undergone large bone resection and allograft transplantation of the knee. Plasma and synovial fluid samples for cytokine measurements [interleukin (IL-1beta, IL-6) and tumour necrosis factor alpha (TNF-alpha)] were drawn from peripheral blood for diagnostic arthrocentesis. Two patients were monitored using consecutive sampling up to 12 months postoperatively. Graft survival was considered excellent, but local or diffuse resorption and also fatigue fractures were seen. These findings show that soluble products of T-cell, macrophage and osteoblast origin, produced as a response to the bone-graft antigens, might be responsible for the bone resorption seen in our material. The elevated IL-1beta and TNF-alpha levels detected support this statement.

Nerve-regenerating effect of 15-deoxyspergualin: Peripheral nerve allotransplants in the rat

We studied the effect of two immunosuppressive agents, 15-deoxyspergualin and cyclosporine A, on various nerve allografts in inbred rats whose major histocompatibility complex was mismatched. As allografts, we used the sciatic nerve (20 mm) and the saphenous nerve (20 mm). We found that 1) fresh peripheral nerve allografts with a short course of 15-deoxyspergualin and cyclosporine A therapy induced more regenerated axons than autografts did, 2) a short course of 15-deoxyspergualin therapy provided better nerve regeneration than cyclosporine A therapy in all forms of nerve allografts and large caliber nerve allografts induced more regenerated axons.

Downsizing of valve allografts for use as right heart conduits

In recent years, there has been a worsening shortage of small and intermediate-sized aortic and pulmonary allografts for use as right ventricular-to-pulmonary artery conduits in infants and children. However, there is a surfeit of large pulmonary and aortic allografts from adult donors. The feasibility of reducing a large allograft to a more useful size was examined using human pulmonary and aortic allografts. Eleven pulmonary allografts (11 to 26 mm in diameter) and nine aortic allografts (5 to 27 mm in diameter) were studied. Valve competence before downsizing was tested with a column of saline to a static pressure equivalent to the normal pulmonary pressure (20 mm Hg). Regurgitant flow was measured for 15 minutes. One complete cusp of the valve was excised, together with a longitudinal strip of the arterial wall. A bicuspid valved conduit was created by suturing the allograft longitudinally. The diameter of the bicuspid valve was measured with a dilator. A nomogram was constructed that predicts the size of the bicuspid allograft based on the size of the original allograft. The competence of the bicuspid allograft was tested and the regurgitant flow was compared with that of the original tricuspid allograft. The transvalvular systolic pressure gradient was measured with the bicuspid allograft placed in a pulsatile extracorporeal perfusion circuit at a flow rale of 1 L/min and a mean pressure of 20.5 ± 2.6 mm Hg. The regurgitant Sow before and after downsizing was 242.9 ± 297.9 mL/15 min and 7.3 ± 9.5 mL/15 min ( p = 0.016), respectively, for pulmonary allografts and 113.6 ± 149.5 mL/15 min and 1.5 ± 2.1 mL/15 min ( p = 0.039), respectively, for aortic allografts. The pressure gradient after downsizing was 1.1 ± 1.3 mm Hg for pulmonary allografts and 2.5 ± 2.1 mm Hg for aortic allografts. The diameter after downsizing ranged from 7 to 18 mm for pulmonary allografts and from 4 to 18 mm for aortic allografts. The linear regression equation with respect to the diameter before downsizing was Y = 0.713X − 1.338 ( r = 0.986) for pulmonary allografts and Y = 0.640X + 0.460 ( r = 0.995) for aortic allografts. Bicuspid allografts were found to be significantly more competent than the original allografts and to have minimal pressure gradients in an in vitro system. We conclude that it is feasible to downsize allografts for use as right ventricular-to-pulmonary artery conduits.

The effect of internal fixation on the healing of large allografts.

One hundred and twenty patients had an allograft reconstruction of the femur, tibia, or humerus. Of a total of 183 allograft-host junctions, eight-three were fixed with a plate; ninety-eight, with an intramedullary rod; and two, with screws alone. There was no significant difference between the rate of union after fixation with a plate and that after intramedullary fixation (p = 1.00). However, fixation with a plate was associated with a higher rate of fracture of the allograft (p < 0.0001). Some problem related to the internal fixation of the allograft was identified at eighteen of the twenty junctions that did not heal. There was a significant association (p < 0.001) between a problem in the achievement of stable fixation and the development of a non-union at the allograft-host junction.

Large bone allografts in the treatment of osteosarcoma

Large cadaveric bone grafts or allografts have been used for the treatment of bone loss for many years. The first recorded large bone allograft was performed by Maceuen in 1881 for bone loss.’ The role of allografts In the treatment of extremity tumors has now been defined and there has been a large experience of the use of allografts in humans.?-’ Osteosarcoma is the most common primary bone tumor and this disease is frequently treated using large bone allografts. In this revjew article, the types of allografts will be defined and their uses outlined. The advantages and disadvantages of allografts will be presented in the light of recent experience.

Audit of a bone bank

The results are reported of an audit of allografts collected in the first 18 months of the Leicester Bone Bank. We retrieved 161 femoral heads at primary arthroplasty of which 103 were implanted into 59 patients. There were deep infections in two recipients and wound infections in five. In two of these cases, culture of the femoral head at implantation was positive but the organisms grown were not those which caused the clinical infection. We retrieved 22 large allografts from six cadavers. Four of these were contaminated at retrieval and required irradiation for sterilisation. There has been one clinical infection in the nine large allografts implanted so far. We recommend that all bone banks undertake prospective audit to ensure that high standards are maintained and wastage minimised.

Frozen musculoskeletal allografts. A study of the clinical incidence and causes of infection associated with their use.

A retrospective study was performed to determine the clinical incidence and causes of infection related to the use of frozen musculoskeletal allografts. The results of this study of 324 grafts, prepared and supplied by our hospital bone bank, showed that the patients in whom femoral head grafts and other small bone and soft-tissue allografts were used had a negligible clinical incidence of infection. The incidence of infection related to the use of large allografts, such as osteoarticular or diaphyseal grafts, was approximately 5 per cent in patients who had treatment for a bone tumor and 4 per cent in those who had revision of a hip arthroplasty. These rates of infection were not substantially different from those that have been reported in similar series in which large allografts or sterilized prosthetic devices were used. The causes of the infections were difficult to determine, but contamination of the allograft was probably not a factor in most patients.

The Use of Large Allografts for Tumor Reconstruction and Salvage of the Failed Total Hip Arthroplasty

Large bone defects have become a more common orthopedic problem in recent year. This is due to the increased enthusiasm for limb salvage surgery as a technique to manage patients with primary bone tumors and for patients who have had multiple joint arthroplasties with subsequent bone loss. One technique that has proven successful for this difficult problem is the use of fresh frozen allografts to reconstruct these skeletal defects. From January 1981 until January 1987, 60 large fragment fresh frozen allografts were used for skeletal reconstruction. These grafts were divided into three basic groups: intercalary, 15; osteoarticular, 16; and allograft-prosthetic composite, 29. The diagnoses included 43 bone tumors, 16 failed total hip arthroplasties, and one traumatic bone loss. The average patient age was 39.7 years and had an average follow-up period of 24 months. The average length of allograft was 12.4 cm. Using the Enneking Functional Evaluation System, the final functional analysis revealed excellent or good results in 86% of the patients and fair or poor results in 14% of the patients. Roentgenological union at the allograft-host bone junction was achieved in 90% of the patients in a mean time of 5.8 months after surgery. An additional three patients obtained union after autogeneic bone grafting. At the time of follow-up evaluation, 92.3% of the patients were free of tumor; they had no local recurrences. The use of fresh frozen allografts represents an acceptable alternative for the reconstruction of large skeletal defects. One can expect good or excellent function for the majority of patients. The best functional results were obtained with the intercalary allografts and the allograft-prosthetic composites.

ＴＨＲ再置換術におけるＡｌｌｏｇｒａｆｔの経験

We presented a case, sixty-six-year-old woman, who had been treated with large allograft for severe structural deficiency about the hip joint associated with prior failed total hip replacement. The acetabulum and a part of the femoral neck were reconstructed with frozen massive allografts. Partial weight bearing was started at three months postoperatively. A year after surgery loosening and proximal migration of the acetabular component were revealed radiografically. We are considering the additional operation for her hip pain.