Allograft-host Bone Junction Research Articles

Reconstructive Allograft Preparation for Long Bone Intercalary Segments After Tumor Resections: Toronto Sarcoma Protocol.

Reconstructive Allograft Preparation for Long Bone Intercalary Segments After Tumor Resections: Toronto Sarcoma Protocol.

Does reverse total shoulder arthroplasty with allograft-prosthesis composite (APC) have surgical benefits over hemiarthroplasty with APC in patients with tumors of the proximal humerus?

The research on surgical outcomes of hemiarthroplasty and reverse total shoulder arthroplasty using allograft-prosthesis composites for the proximal humeral oncologic condition is still scarce. Therefore, this study aimed to compare surgical outcomes of shoulder joint reconstruction with hemiarthroplasty and reverse total shoulder arthroplasty using allograft-prosthesis composites for tumors of the proximal humerus. Eleven patients underwent hemiarthroplasty or reverse total shoulder arthroplasty using allograft-prosthesis composites for tumors of the proximal humerus between July 2011 and April 2018 were reviewed. Radiographic analysis for bone union of allograft-host bone junction, implant loosening, stress shielding and shoulder dislocation or subluxation was performed. Functional outcomes were evaluated using visual analog scales for pain, range of motion, Simple Shoulder Test score and Musculoskeletal Tumor Society score. Furthermore, oncologic outcome and complications were also assessed, respectively. There were five patients with hemiarthroplasty (mean age, 23.2years) and six patients with reverse total shoulder arthroplasty (mean age, 46.8years, P=0.05). Radiographically, there were no events associated with implant loosening, stress shielding and shoulder dislocation or subluxation in the two groups. There were no differences in functional outcomes between the two groups. There was no local recurrence in entire cohort. In the hemiarthroplasty group, one patient was required revision surgery to reverse total shoulder arthroplasty at postoperative 6years due to rotator cuff dysfunction. In the reverse total shoulder arthroplasty group, one patient showed the fracture occurred at allograft-host bone junction at postoperative 6months. Surgical outcomes of hemiarthroplasty with allograft-prosthesis composites were not inferior to reverse total shoulder arthroplasty when applied in properly selected patients. The authors recommended that hemiarthroplasty with allograft-prosthesis composites could be used for young age patients without glenoid metastasis involvement, and reverse total shoulder arthroplasty with allograft-prosthesis composites could be used for patients with old age or metastatic bone tumors.

Is the Capanna Technique a Reliable Method for Revision Surgery after Failure of Previous Limb-Salvage Surgery?

Reconstruction of a massive bone defect caused by previous failed limb-salvage surgery in patients with bone sarcoma is challenging. Many procedures have been used, but they all have their inherent disadvantages. The Capanna technique has demonstrated good functional outcomes and a low incidence of complications in primary reconstructive surgery of massive bone defect. However, few studies have focused on its usage in revision surgery after failed primary limb-salvage surgery. Between June 2011 and January 2017, 13 patients underwent revision surgery with the Capanna technique for reconstruction of a secondary segmental bone defect caused by a previous failed surgical procedure. The demographics, operating procedures, graft union, functional outcomes, oncologic outcomes, and postoperative complications of each patient were recorded. The current study investigated 13 patients. The rate of limb salvage was 100 %. Bone union was achieved for all patients during a mean time of 8.54 ± 2.15 months (range 4-11 months) at the fibula-host bone junction and 14.92 ± 2.33 months (range 12-21 months) at the allograft-host bone junction. The postoperative complications included wound healing issues and internal fixation loosening. Allograft fracture, nonunion, and infection were not observed. All the patients achieved good functional outcomes, with a Musculoskeletal Tumor Society (MSTS) score of 0.86 ± 0.03 at the latest follow-up visit. The Capanna technique is a reliable alternative method for revision reconstruction of a segmental bone defect caused by a previous failed surgical procedure. Level IV, therapeutic study.

Reverse-reamed Intercalary Allograft: A Surgical Technique

Allograft reconstruction of large segmental intercalary bone defects after tumor resection is a well-accepted surgical technique. Although results generally have been satisfactory, nonunion at the allograft-host bone junction site remains a notable concern. Various reports have described attempts to enhance junctional healing with a variety of complex osteotomies, often complicating an already complex procedure. The use of an innovative reverse reaming technique can decrease the level of intraoperative difficulty mating the allograft-host junction and theoretically may improve junctional healing by enhancing stability and increasing the contact surface area.

Vascularized Periosteal Flaps Accelerate Osteointegration and Revascularization of Allografts in Rats.

Surgical reconstruction of large bone defects with structural bone allografts can restore bone stock but is associated with complications such as nonunion, fracture, and infection. Vascularized reconstructive techniques may provide an alternative in the repair of critical bone defects; however, no studies specifically addressing the role of vascularized periosteal flaps in stimulating bone allograft revascularization and osseointegration have been reported. (1) Does a vascularized periosteal flap increase the likelihood of union at the allograft-host junction in a critical-size defect femoral model in rats? (2) Does a vascularized periosteal flap promote revascularization of a critical-size defect structural bone allograft in a rat model? (3) What type of ossification occurs in connection with a vascularized periosteal flap? Sixty-four rats were assigned to two equal groups. In both the control and experimental groups, a 5-cm critical size femoral defect was created in the left femur and then reconstructed with a cryopreserved structural bone allograft and intramedullary nail. In the experimental group, a vascularized periosteal flap from the medial femoral condyle, with a pedicle based on the descending genicular vessels, was associated with the allograft. The 32 rats of each group were divided into subgroups of 4-week (eight rats), 6-week (eight rats), and 10-week (16 rats) followup. At the end of their assigned followup periods, the animals were euthanized and their femurs were harvested for semiquantitative and quantitative analysis using micro-CT (all followup groups), quantitative biomechanical evaluation (eight rats from each 10-week followup group), qualitative confocal microscopic, backscattered electron microscopic, and histology analysis (4-week and 6-week groups and eight rats from each 10-week followup group). When making their analyses, all the examiners were blinded to the treatment groups from which the samples came. There was an improvement in allograft-host bone union in the 10-week experimental group (odds ratio [OR], 19.29 [3.63-184.50], p < 0.05). In contrast to control specimens, greater bone neoformation in the allograft segment was observed in the experimental group (OR [4-week] 63.3 [39.6-87.0], p < 0.05; OR [6-week] 43.4 [20.5-66.3], p < 0.05; OR [10-week] 62.9 [40.1-85.7], p < 0.05). In our biomechanical testing, control samples were not evaluable as a result of premature breakage during the embedding and assembly processes. Therefore, experimental samples were compared with untreated contralateral femurs. No difference in torsion resistance pattern was observed between both groups. Both backscattered electron microscopy and histology showed newly formed bone tissue and osteoclast lacunae, indicating a regulated process of bone regeneration of the initial allograft in evaluated samples from the experimental group. They also showed intramembranous ossification produced by the vascularized periosteal flap in evaluated samples from the experimental group, whereas samples from the control group showed an attempted endochondral ossification in the allograft-host bone junctions. A vascularized periosteal flap promotes and accelerates allograft-host bone union and revascularization of cryopreserved structural bone allografts through intramembranous ossification in a preclinical rat model. If large-animal models substantiate the findings made here, this approach might be used in allograft reconstructions for critical defects using fibular or tibial periosteal flaps as previously described.

The combinative biological reconstruction of bony defect following limb bone tumor resections

Objective To analyze the image and histological results of the combined use of allograft/extracorporeally frozen tumor-bearing bone and vascularized fibular flap for the reconstruction of bony defects following tumor resection, guiding clinical practice. Methods From March 2007 to June 2013, we enrolled 63 patients who had combinative biological reconstruction after bone tumor resection(11 in humerus, 22 in femur, 21 in tibia, 4 in calcaneus). There were 36 male and 27 female in this series. The average age at time of operation was 20 years, ranging from 9 to 48 years. The follow-up ranged from 16 to 102 months with average of 48 months. We investigated the X-ray and CT images for all patients and histological findings of two patients. Patients were assessed functionally with the Musculoskeletal Tumor Society 93 score. Results Three patients with local soft tissue recurrence and one patient with infection underwent amputation. The survival of construct was 93.6%. Bone union achieved in all cases with the average MSTS score of 92.8%. Bone union ranged from 11 to 28 months in allograft group and 9 to 14 months in devitalized tumor bearing bone group. Significant difference of bone union time was found between two groups(Z=-3.638, P=0.000).Viability of the fibular grafts was verified in 58 of 63 patients(92%).Three types of images were observed in complex. Osteopenia and spongy change in fibula were found in 51 patients(81%)with stable fixation of the complex. Five complexes with failed blood supply of fibula and stable fixation revealed no density change of fibula, small amount of callous formation and relative delayed union. In seven complexes(11%)with unstable complex due to patients' incompliance, fibula reacted with dense hypertrophy and micro-fracture. Fusion of grafts with amount of callus was obviously observed. Union at allograft-host bone junctions occurred by residual host bone-derived external callus and fibular-derived internal callus that bridged the junction and filled the gap between abutting cortices. Callus from fibular graft was mature than that from periosteum of residual host bone. Internal repair was observed at the internal surface of the allografts. Fibula showed significant spongy changes. Conclusion Recycled tumor-bearing bone in combined with fibular flap is a reliable reconstruction as an alternative to traditional Capanna technique. The survival of the fibula is a cornerstone in success of complex reconstruction. Sponginess of fibula and internal repair of allograft compromise the intensity of complex, necessitating the strong instrumentation during reconstruction. Key words: Extremities; Bone neoplasms; Bone transplantation; Histology

Allograft-prosthetic composite reverse total shoulder arthroplasty for reconstruction of proximal humerus tumor resections

Proximal humerus reconstructions after resection of tumors are challenging. Early success of the reverse shoulder arthroplasty for reconstructions has recently been reported. The reverse allograft-prosthetic composite offers the advantage of improved glenohumeral stability compared with hemiarthroplasty for proximal humeral reconstructions as it uses the deltoid for stability. This article describes the technique for treating proximal humeral tumors, including preoperative planning, biopsy principles, resection pearls, soft tissue tensioning, and specifics about reconstruction using the reverse allograft-prosthetic composite. Two cases are presented along with the functional outcomes with use of this technique. Biomechanical considerations during reconstruction are reviewed, including techniques to improve the deltoid compression force. Reported instability rates are less with reverse shoulder arthroplasty reconstruction as opposed to hemiarthroplasty or total shoulder arthroplasty reconstructions of tumor resections. Reported functional outcomes are promising for the reverse allograft-prosthetic composite reconstructions, although complications are reported. Reverse allograft-prosthetic composites are a promising option for proximal humeral reconstructions, although nonunion of the allograft-host bone junction continues to be a challenge for this technique.

Innovative Trident Fixation Technique for Allograft Knee Arthrodesis for High-grade Osteosarcoma around the Knee†

Reconstruction for osteosarcoma around the knee after wide resection faces the challenge of great bone defect and future limb length discrepancy in the skeletally immature patients. Modern prosthetic reconstruction may provide good results, but the longevity may be of concern and may not be affordable in certain communities. Allograft knee arthrodesis still has its role in light of bone stock preservation and cost-effectiveness. We developed the innovative trident fixation technique utilizing three Steinmann pins to minimize limb length inequality without jeopardizing knee fusion stability. Twelve patients were enrolled. The mean age was 11.5 (10-13) years. Two had high-grade osteosarcoma in proximal tibia and others in distal femur. Two patients died of oncological disease. The median follow-up of the disease-free 10 patients was 47 (41-60) months. All allograft-host bone junctions healed uneventfully without major complications except one allograft fracture. The average limb length discrepancy was 1.45 (1.0-2.1) cm at latest follow-up. This straightforward technique was successful in knee arthrodesis with minimized limb length inequality. Accordingly, in light of bone stock preservation and longevity for the young children, it may be a surgical alternative for malignant bone tumors around the knee.

Intramedullary Step-Cut Osteotomy for Revision Total Hip Arthroplasty with Allograft-Host Bone Size Mismatch

Eleven revision total hip arthroplasties were treated with proximal segmental femoral allograft reconstruction in which the diameter of the distal host bone was larger than the largest long-stem femoral component which could fit into the segmental allograft. A long, lateral step-cut osteotomy of the allograft was used with placement of the lateral cortical allograft inside the distal host bone. All allograft-host bone junctions healed. The average time to union was 6.7 months. The long step-cut osteotomy provides stability of the allograft-host bone junction when the diameter of the host bone is larger than the allograft. The osteotomy also provides a large surface area of contact between the allograft and host bone.

Structural Allograft for Management of Severe Bone Defectin Revision Total Knee Arthroplasty

Purpose : To analyze the clinical and radiographic results after revision total knee arthroplasty using a structural allograft for large bone defects. Materials and Methods : 184 cases of revision total knee arthroplasty were performed from January 1992 to February 2003. Among them, 52 knees in 48 patients with the use of structural allograft for the management of large bone defects were retrospectively reviewed. Those 52 knees have been followed until recently. The average follow-up period was 5 years and 6 months. Freshfrozen femoral head was used as the structural allograft in all knees. The clinical rating system of the American Knee Society was used for the clinical assessment. Union at the allograft-host bone junction, femoro-tibial angle and periprosthetic radiolucent lines using a radiographic evaluation of American Knee Society were analyzed radiographically. Results : At the final follow-up, the mean preoperative knee and function score improved from 38.6 points to 82.6 and 30.3 to 76.4, respectively. Radiographically, union of the allograft to the host bone was observed in all knees. The average femoro-tibial angle was corrected from 1.8° in valgus to 6.2°. The radiographic evaluation revealed no evidence of loosening. Conclusion : Revision total knee arthroplasty using a femoral head allograft is an appropriate surgical method for treating large bone defects.

Porous poly(propylene fumarate) foam coating of orthotopic cortical bone grafts for improved osteoconduction.

A porous biodegradable scaffold coating for perforated and demineralized cortical bone allografts could maintain immediate structural recovery and subsequently allow normal healing and remodeling by promoting bony ingrowth and avoiding accelerated graft resorption. This new type of osteoconductive surface modification should improve allograft incorporation by promoting new bone growth throughout the biodegradable scaffold, hence encasing the graft with the recipient's own bone. We investigated the feasibility of augmenting orthotopically transplanted cortical bone grafts with osteoconductive biodegradable polymeric scaffold coatings. Five types of bone grafts were prepared: type I, untreated fresh-frozen cortical bone grafts (negative control); type II, perforated and partially demineralized cortical bone grafts without additional coating (positive control); type III, perforated and partially demineralized cortical bone coated with a low-porosity poly(propylene fumarate) (PPF) foam; type IV, perforated and partially demineralized cortical bone coated with a medium-porosity PPF foam; and type V, perforated and partially demineralized cortical bone coated with a high-porosity PPF foam. Grafts were implanted into the rat tibial diaphysis. Fixation was achieved with an intramedullary threaded K-wire. Two sets of animals were operated on. Animals were killed in groups of eight with one set being killed 12 weeks, and the other 16 weeks, postoperatively. Radiographic, histologic, and histomorphometric analyses of grafts showed that the amount of new bone forming around the foam-coated grafts was significantly higher than that in the type I control group (uncoated) or that in type II group (perforated and partially demineralized cortical bone grafts). Although all foam formulations appeared initially equally osteoconductive, histologic evaluation of medium-porosity PPF foam-based coatings appeared to result in a sustained response 16 weeks postoperatively. Significant resorption was present in perforated and partially demineralized cortical bone graft allografts, with some accompanying new bone formation occurring primarily within the laser holes. Therefore, PPF foam-coated cortical bone grafts appeared to be better protected from excessive bone resorption, as frequently seen with invasion of fibrovascular tissue. Biomechanical analysis of the PPF foam-coated grafts corroborated findings of the morphometric analysis in that the failure strength at the allograft-host bone junction sites of all PPF-coated cortical bone grafts was higher than in the uncoated controls.

The effect of recombinant human bone morphogenetic protein-2 on femoral reconstruction with an intercalary allograft in a dog model

This study compared the effect of augmentation of allograft–host bone junctions with recombinant human bone morphogenetic protein-2 (rhBMP-2) on an absorbable collagen sponge (ACS), autogenous cancellous bone graft (CBG), and a collagen sponge alone in a canine intercalary femoral defect model repaired with a frozen allograft. Outcome assessment included serial radiographs, dual energy X-ray absorptiometry scans, and gait analyses, and mechanical testing and histology of post-mortem specimens. The distal junction healed more quickly and completely with rhBMP-2 than ACS alone based on qualitative radiography and histologic evaluations. The primary tissue in the unhealed gaps in the ACS group was fibrous connective tissue. The proximal allograft–host bone junction had complete bone union in the three treatment groups. There was significantly greater new bone callus formation at both junctions with rhBMP-2 than with CBG or ACS alone that resulted in increased bone density around the allograft–host bone junctions. All dogs shifted their weight from the treated leg to the contralateral pelvic limb immediately after surgery. Weight bearing forces were redistributed equally between the pelvic limbs at 12 weeks after surgery with rhBMP-2, at 16 weeks after surgery with CBG, and at 24 weeks after surgery with ACS alone. Bending and compressive stiffnesses of the whole treated femora were equal to the contralateral control femora in all treatment groups, whereas torsional rigidities of the whole treated femora for the CBG and ACS groups were significantly less than the control. Both the proximal and distal junctions the treated with rhBMP-2 had torsional stiffnesses and strengths equal to intact control bones. Ultimate failure torques of the proximal junctions of the CBG group and of both junctions of the ACS group were significantly less than the BMP-treated bones. Augmentation of the allograft–host bone junctions with rhBMP-2 on an ACS gave results for all parameters measured that equaled or exceeded autogenous graft in this canine intercalary femoral defect model.

Histomorphometric description of allograft bone remodeling and union in a canine segmental femoral defect model: a comparison of rhBMP-2, cancellous bone graft, and absorbable collagen sponge

The purpose of this study was to determine the effect of recombinant human bone morphogenetic protein type 2 (rhBMP-2) on the histomorphometry of femoral allograft-host bone union and allograft remodeling. A 6 cm mid-diaphyseal femoral defect was created and filled with an allograft stabilized with an interlocking nail in 21 dogs. Dogs were randomly divided into three equal groups and the allograft-host bone junctions and the mid-diaphyses of the allografts were treated with either an absorbable collagen sponge (ACS) loaded with rhBMP-2 (BMP group), an autogenous cancellous bone graft (CBG group), or ACS loaded with buffer solution (ACS group). All dogs received daily tetracycline until sacrifice at 24 weeks to label new bone formation. Histomorphometric analyses on sections of proximal and distal allograft-host bone junctions and the mid-diaphyseal portion of allografts were performed using fluorescent and regular light microscopy. Analyses of the host bone and junctions between allograft and host bone revealed significantly greater new bone formation and larger osteon radii in the BMP group compared to CBG and ACS groups and contralateral intact bone. Porosity in CBG and ACS groups was significantly higher than in the BMP group, which had similar values to intact bone. In transverse sections of allografts, the largest pore diameters were present in the CBG group. Based on all parameters measured, significantly higher bone turnover occurred in the outer cortical area of the allograft in all groups as compared to the inner cortical and mid-cortical areas. New bone formation and osteon radius/osteon width in allografts were similar for all three groups. Higher porosity and larger pore diameters in the CBG and ACS groups suggested higher bone resorption versus formation in these groups compared to the BMP group. The results of this study reveal more balanced allograft bone resorption and bone formation in the BMP group, with greater resorptive activity in the CBG and ACS groups. However, neither rhBMP-2 nor autogenous bone graft increased allograft incorporation when compared to the negative control (ACS group).

Scintigraphy of lower extremity cadaveric bone allografts in osteosarcoma patients.

To describe scintigraphic characteristics of bone allografts used in limb salvage reconstruction after resection of lower extremity osteosarcoma. The authors reviewed 85 skeletal scintigrams of 20 pediatric patients followed up for 0.5-5.7 years after resection of lower extremity osteosarcoma and allograft reconstruction. Uptake in the allograft and adjacent host tissues was assessed visually. Lack of tracer uptake in the allografts was seen in 99% of the studies and a faint rim of tracer localization outlining the allograft's periphery was seen in 95% of the studies. Increased uptake was noted at the allograft-host bone junction in 78% of the studies. Uptake was increased in the joint surfaces of native bones articulating with allografts (97% of studies), including the patella (93% of studies) when the knee was involved. These findings were stabilized as time passed. Cadaveric bone allografts have a characteristic scintigraphic appearance in this selected patient group that reflects the physiology of their incorporation process.

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.