In vitro and In vivo study on the effect of autogenous cancellous bone and intramedullary polymethylmethacrylate on allograft construct strength

An in vitro study was performed to compare the effects of augmenting interlocking nails of one of two diameter (5 or 6 mm) with intramedullary polymethylmethacrylate. Subsequently, an in vivo study was performed to compare the effects of augmenting the interlocking nail with five combinations of intramedullary polymethylmethacrylate and autogenous cancellous bone applied to the periosteal surface or within the medullary canal. Dogs were killed 6 months after the procedure for biomechanical evaluation of the femora in axial compression, mediolateral and craniocaudal bending, and torsion. Results from the in vitrostudy at the proximal osteotomy indicated the 6-mm inteilocking nail with intramedullary polymethylmethacrylate had greater stiffness than the 5-mm interlocking nail without it (p < 0.05). At the distal osteotomy, regardless of the diameter of the interlocking nail, the addition of intramedullary polymethylmethacrylate increased stiffness (p < 0.05). Results from the in vivo study indicated greater global construct stiffness with an interlocking nail alone, an interlocking nail augmented with intramedullary polymethylmethacrylate and cancellous bone at the periosteal surface, and an interlocking nail augmented with cancellous bone within the medullary canal and at the periosteal surface (p < 0.05). At the osteotomy level, the interlocking nail augmented with intramedullary polymethylmethacrylate and cancellous bone at the periosteal surface had greater stiffness than did an interlocking nail alone or an interlocking nail augmented with either intramedullary polymethylmethacrylate. cancellous bone within the medullary canal, or cancellous bone at the periosteal surface (p < 0.05) but produced the same results as an interlocking nail augmented with cancellous bone within the medullary canal and at the periosteal surface. The results suggest that augmenting interlocking nail fixation with intramedullary polymethylmethacrylate by itself offers no advantage but that acombination of intramedullary polymethylmethacrylate and cancellous bone at the periosteal surface improves structural properties at 6 months.     

The effect of intramedullary polymethylmethacrylate on healing of intercalary cortical allografts in a canine model.

The purpose of this study was to evaluate the effect of intramedullary polymethylmethacrylate (PMMA) bone cement on the healing of intercalary allografts. Thirteen adult beagles had bilateral intercalary femoral allografts implanted. The medullary canal of one randomly assigned allograft in each dog was filled with PMMA. Healing was followed clinically and femora were evaluated radiographically, biomechanically, histologically, and histomorphometrically 9 months after surgery. There was an increased percent of eroded surface at the endosteal area of the center region of grafts containing PMMA and there was an increased percent osteoblast surface in this area in grafts not containing PMMA. There was an increased percent eroded surface at the periosteal area in the center region in grafts not containing PMMA and there was an increased percent osteoblast surface at the periosteal area in the graft adjacent to the host junction in grafts containing PMMA. There was no significant difference between PMMA-treated and untreated allografts in any other parameters measured. The results from this study suggest that, although the pattern of incorporation is altered, intramedullary PMMA does not appear to effect allograft healing adversely.     

异体脱蛋白松质骨复合纤维蛋白BMP修复兔桡骨缺损

[目的]探讨以纤维蛋白复合脱蛋白松质骨作为骨形态发生蛋白（BMP）的载体修复兔节段性骨缺损。[方法]于36只青紫蓝兔两侧桡骨干处造成1．5cm缺损，采用三种方法进行处理：A组，植入脱蛋白松质骨、纤维蛋白、BMP的复合物；B组，植入脱蛋白松质骨；C组，空白对照。术后2、4、8、12、16周进行放射学、组织学和电镜检查。[结果]A组骨缺损区在成骨活跃程度、骨再生量和再生髓腔结构等方面均显著优于B组，使骨缺损得到了较彻底的修复。B、C两组均不能产生骨性愈合。[结论]脱蛋白松质骨复合纤维蛋白是较理想的BMP载体材料，以三者的复合物修复骨缺损可达到满意效果。     

The fate of cancellous and cortical bone after transplantation of fresh and frozen tissue-antigen-matched and mismatched osteochondral allografts in dogs

After implantation, a massive osteochondral allograft cannot be completely protected from the stresses that are produced by weight-bearing, and it is susceptible to collapse during incorporation, revascularization, and substitution. How these processes are affected by disparities between the tissue antigens of the host and the graft remain unclear. To clarify the role of histocompatibility antigen-matching in the incorporation of cancellous and cortical bone, we orthotopically implanted both fresh and cryopreserved dog leukocyte-antigen-matched and mismatched proximal osteochondral radial allografts in beagles. Four groups of beagle dogs were used; they received (1) a dog leukocyte-antigen-mismatched frozen allograft, (2) a dog leukocyte-antigen-mismatched fresh allograft, (3) a dog leukocyte-antigen-matched fresh allograft, or (4) a dog leukocyte-antigen-matched frozen allograft. In twelve dogs, a sham operation was done in the contralateral limb (the first living donor had a sham operation), and in the remaining ten dogs, the proximal part of the contralateral radius was removed and then replaced as an autogenous (control) graft. The animals were given fluorochromes periodically, and they were killed eleven months after the operation. The osseous portion of the grafts was evaluated radiographically, biomechanically, and histomorphometrically. No dog had grossly obvious clinical abnormalities, all host-graft interfaces healed, and no joints dislocated. Radiographic examination of the allografts frequently showed deformation of the radial head and variable peripheral resorption. No significant difference in the modulus of elasticity at the host-graft interface was found among the groups. The repair process of the cortical bone was similar for all grafted segments. New periosteal and endosteal bone formed, and the cortical bone became porotic as vessels penetrated it. The uptake of fluorochrome was the most active in the autogenous grafts and the least active in the fresh antigen-mismatched grafts. The volume of cancellous bone was significantly greater and the trabeculae were thicker in all allografts compared with the bones on which a sham operation had been done and compared with the autogenous grafts. The volume of intertrabecular fibrous connective tissue was directly proportional to the immunogenicity of the allografts, and the percentage of the surface on which bone was forming tended to be inversely proportional to the immunogenicity of the allografts. The grafts were revascularized by the ingrowth of vessels into the intertrabecular spaces; necrotic trabeculae were not penetrated by vessels. This pattern was particularly pronounced in the antigen-mismatched grafts, regardless of whether they were fresh or frozen.(ABSTRACT TRUNCATED AT 400 WORDS)     

钻孔复合浓缩骨髓对兔结构性骨移植愈合的影响

目的 观察异体骨钻孔并复合自体浓缩骨髓移植对兔骨缺损的修复和重建能力,为临床结构性骨移植提供新方法.方法 将36只日本大耳白兔随机分成三组,每组12只,制成左侧股骨中段3 cm缺损,分别采用不同方式处理过的同种异体骨进行移植,A组:植入未打孔异体骨+骨泥;B组:植入打孔异体骨+骨泥;C组:植入打孔异体骨+骨泥浓缩骨髓复合物.术后3个月分别行x线片、组织学观察、骨密度测定和生物力学测试. 结果 ①放射学检查:A组仅在供.宿结合部可见有骨痂包绕,异体骨周围无明显骨痂;B组及C组整个移植骨段周围均可见明显骨痂,C组骨痂延伸范围更广.②组织学观察:三组异体骨供.宿结合部均完全吸收,被大量骨痂取代且塑形良好;中间横断面A组异体骨周围可见少量内骨痂,B组可见少量内骨痂及外骨痂且被大量纤维结缔组织所分隔;C组异体骨可见大量内外骨痂生长,髓腔内充满骨母细胞,外骨痂骨小梁已相互融合形成编织网状骨,但与异体骨间仍被纤维结缔组织间断分隔.③平均骨密度值测定:C组高于A、B组及对侧正常股骨,差异有统计学意义(P＜0.05).④力学性能检测:A、B、C三组间最大载荷比较,差异无统计学意义(P＞0.05),A、B、C组均低于对侧正常股骨(P＜0.05). 结论 钻孔并复合浓缩骨髓能促进大段移植骨的早期活化,提高新骨产量.     

Revascularization and bone remodeling of frozen allografts stimulated by intramedullary sustained delivery of FGF‐2 and VEGF

Frozen bone allografts are susceptible to nonunion and fracture due to limited revascularization and incomplete bone remodeling. We aim to revascularize bone allografts by combining angiogenesis from implanted arteriovenous (AV) bundles with delivery of fibroblast growth factor (FGF‐2) and/or vascular endothelial growth factor (VEGF) via biodegradable microspheres. Rat femoral diaphyseal allografts were frozen at ?80°C, and heterotopically transplanted over a major histocompatibility mismatch. A saphenous AV bundle was inserted into the intramedullary canal. Growth factor was encapsulated into microspheres and inserted into the graft, providing localized and sustained drug release. Forty rats were included in four groups: (I) phosphate‐buffered saline, (II) FGF‐2, (III) VEGF, and (IV) FGF‐2 + VEGF. At 4 weeks, angiogenesis was measured by the hydrogen washout method and microangiography. Bone remodeling was evaluated by quantitative histomorphometry and histology. Bone blood flow was significantly higher in groups III and IV compared to control (p < 0.05). Similarly, bone remodeling was higher in VEGF groups. FGF‐2 had little effect on allograft revascularization. No synergistic effect was observed with use of both cytokines. Delivered in microspheres, VEGF proved to be a potent angiogenic cytokine, increasing cortical bone blood flow and new bone formation in frozen allografts revascularized with an implanted AV bundle. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29: 1431–1436, 2011     

Ununited diaphyseal forearm fractures with segmental defects: plate fixation and autogenous cancellous bone-grafting

BACKGROUND: With current techniques of plate-and-screw fixation, diaphyseal nonunions of the radius and ulna are unusual. The few reports that have been published have discussed the use of structural corticocancellous bone grafts for the treatment of atrophic nonunions that are associated with osseous defects. We reviewed the rate of union and the functional results in association with the use of plate-and-screw fixation and autogenous cancellous (nonstructural) bone grafts. METHODS: Thirty-five patients with an atrophic ununited diaphyseal fracture of the forearm were treated with 3.5-mm plate-and-screw fixation and autogenous cancellous bone-grafting. A segmental osseous defect with an average size of 2.2 cm (range, 1 to 6 cm) was present in each patient. Twenty of the original fractures had been open. Eleven patients had had treatment of a deep infection before referral to us. The nonunion involved both forearm bones in eight patients, the radius alone in sixteen patients, and the ulna alone in eleven patients. RESULTS: The atrophic nonunion was associated with an open fracture in twenty patients, suboptimal fixation in twenty-two, a fracture-dislocation of the forearm in nine, and infection in eleven. All fractures healed without additional intervention within six months. Two patients had a subsequent Darrach resection of the distal part of the ulna for the treatment of arthrosis of the distal radioulnar joint. After an average duration of follow-up of forty-three months, the final arc of motion averaged 121 degrees in the forearm, 131 degrees at the elbow, and 137 degrees at the wrist, with an average grip strength of 83% compared with that of the contralateral limb. According to the system of Anderson and colleagues, five patients had an excellent result, eighteen had a satisfactory result, eleven had an unsatisfactory result (because of elbow stiffness related to associated elbow injuries in three and because of wrist stiffness in eight), and one had a poor result (because of malunion). CONCLUSIONS: When the soft-tissue envelope is compliant, has limited scar, and consists largely of healthy muscle with a good vascular supply, autogenous cancellous bone-grafting and stable internal plate fixation results in a high rate of union and improved upper limb function in patients with diaphyseal nonunion of the radius and/or ulna.     

The effects of motion on the healing of cancellous bone

In 20 dogs olecranon osteotomies fixed with tension band wires were studied histologically to reveal the pattern of healing. Different degrees of stability existed in different areas of the osteotomy. Under stable conditions cancellous bone healed by direct formation of woven bone. Instability resulted in an internal cartilaginous callus. Once stability was restored, the callus underwent endochondral ossification. The articular defect, which was in an area of maximum instability, healed by fibrocartilage.     

Tissue-typing in human massive allografts of frozen bone

The cases of twenty-six patients who received a massive allotransplant of frozen bone, with a known degree of histocompatibility between the donor and the recipient, were studied. Twenty-two patients were followed for more than two years (range, twenty-four to ninety-two months). Twenty-three biopsies were performed in sixteen patients from nine to seventy-eight months after transplantation. No clear relationship could be established between the degree of histocompatibility of the donor and the recipient and the incorporation of the graft, probably in part due to the number of variables involved and the polymorphism of the HLA system. However, no early massive resorption of the transplant was seen in this series, in which, by the design of the protocol, no recipients had pre-existing circulating antibodies to the antigens of the donor. Two allografts showed infiltration by round cells and vascular lesions in the absence of infection, which is suggestive of an immune response against antigens from the donor. Both matched poorly with the donor for HLA antigens. The individual who had the strongest reaction was the only recipient in the series who had a massive failure of the transplant.     

含锌煅烧牛松质骨修复兔桡骨缺损的研究

目的　探讨单纯煅烧牛松质骨及含锌煅烧牛松质骨材料修复骨缺损的作用。方法　将煅烧骨及含锌煅烧骨植入兔桡骨缺损 ,术后 4、8、12、2 4周行X线评分 ,12、2 4周行组织形态学观察、评分 ,比较植入材料的成骨作用。结果　术后不同时间X线评分左侧分别为 6 .87± 0 .2 3、8.2 3± 0 .41、10 .2 8± 0 .41、13 .0 0± 1.0 0 ;右侧分别为 4.2 9± 0 .41、6 .5 0± 0 .49、7.43± 0 .49、8.2 8±0 .41。左侧评分均明显高于右侧 (P <0 .0 5 )。组织学评分左侧分别为 8.2 3± 0 .41、10 .16± 0 .36 ;右侧为 6 .43± 0 .49、8.36± 0 .41。左侧评分均明显高于右侧 ( P <0 .0 5 )。结论　煅烧骨及含锌煅烧骨均有修复骨缺损的能力 ,但以含锌煅烧骨较为理想。     

The effect of histocompatibility matching on canine frozen bone allografts

The value of histocompatibility matching in frozen bone allografts was studied in a canine cancellous ulnar segmental-replacement model. Frozen bone that was exchanged across strong and weak transplantation barriers was evaluated histologically and radiographically at thirteen and twenty-six weeks after grafting. Histological grading criteria quantified the type of union at each end of the graft and the degree of remodeling of the marrow, spongiosa, and compacta. Radiographic grading criteria included the presence of union at each end of the graft and the degree of remodeling of the graft segment. In vitro studies for serum antibody and cell-mediated immunity were carried out by isotopic cytotoxicity methods at seven intervals during the twenty-six-week study period. Histologically, the strong-barrier allografts had fewer osseous unions and less reorganization of spongiosa and marrow when compared with autograft controls at both thirteen and twenty-six weeks. Radiographically, the strong-barrier allografts at thirteen weeks had fewer unions and marked resorption of grafts material when compared with autograft controls. There were no differences between weak transplantation-barrier grafts and control autografts radiographically or histologically at thirteen and twenty-six weeks after grafting. Frozen bone allografts did not elicit detectable serum antibody or lymphocytes that were cytotoxic for donor cells.     

兔自体松质骨颗粒修复关节软骨损伤

目的研究兔自体松质骨颗粒在膝关节软骨损伤处移植后能够诱导软骨组织生成、促进关节软骨损伤修复的现象。方法 12只新西兰大白兔麻醉后在兔的右侧膝关节股骨远端内、外侧髁负重区用电钻分别造成直径、深度均为3 mm的骨软骨缺损创面,取同侧髂骨松质骨,制成直径约为1 mm松质骨颗粒植入股骨内侧髁软骨缺损处,作为实验组,外侧髁软骨缺损不做处理作为对照组。术后12周进行膝关节大体观察、病理切片染色,评估关节软骨损伤的修复情况。结果兔膝关节实验组软骨缺损处被新生软骨填充,软骨面光滑,组织切片染色显示有关节软骨形成。对照组缺损创面仍然凹陷,仅在缺损边缘有少量软骨生长。结论兔自体松质骨颗粒在膝关节软骨损伤处能够诱导软骨生成,促进关节软骨的修复,是一种良好的关节软骨损伤修复方法。     

Attachment of autogenous tendon graft to cortical bone is better than to cancellous bone

We analyzed the mechanical and histological variables after the attachment of an autogenous tendon graft to cortical or cancellous bone. We reconstructed the medial collateral ligament of the knee in 33 Japanese white rabbits, using a bone socket procedure. The floor of the bone socket was cortical bone in group A and cancellous bone in group B.

Mechanically, the pull-out test showed a tendency towards an increase in maximum failure load, with 10.9 N, 35 N and 37 N in group A, and 11 N, 18 N and 36 N in group B at 2, 4 (statistically significant difference) and 8 weeks after surgery, respectively. Histologically, the attachments were immature at 2 weeks. At 4 weeks, granulations had matured and Sharpey's fiber-like structures were seen. These fibers were more abundant in group A than in group B. At 8 weeks, the attachments in both groups were rather like the normal 4-zone structure. With time, tendon attachments matured in both groups.

Our study showed that reattachment of tendons to cortical bone may be bettter than to cancellous bone.     

Special devices and instruments a new instrument for harvesting autogenous cancellous bone

Principle The set of instruments allows harvesting autogenous cancellous bone from the anterior or posterior iliac crest. Special punches (Figures 3 and 4) introduced through rotary movements will detach cancellous bone from its bed and the graft will be secured in the punch through compression. Corresponding pestles will be used to extrude the bone graft while compressing it further. This then supplies small firm cylinders of cancellous bone.     

Mandible reconstruction and autogenous frozen bone graft: experimental study on rats

The aim of this study was to evaluate the biological behaviour of a frozen bone graft in orthotopic and heterotopic sites in the rat. The previous experimental study on this subject was published 25 years ago without sufficient detail about the histology and comparison between the orthotopic and ectopic sites. Therefore, being very important for future clinical application, we decided to evaluate the frozen bone graft using rats. The procedure was performed on two groups of five rats each (Charles River). After wide dissection of the inferior border of the mandible from the surrounding muscle, an inferior segmental resection 4 mm in length was performed, taking care not to fracture the superior part and to maintain mucosal integrity. This segment was placed in liquid nitrogen for two periods of 10 minutes each with a third period to allow it to reach room temperature. In the first group (A), the frozen segment was placed ectopically in a gluteal muscle pocket, and in the second group (B), the frozen bone was fixed in the same position in the same mandible. After 1 month of follow-up, the animals were killed, the bone graft was removed, and histology was performed. Results were consistent in both groups. In group A, the segment was surrounded by strong inflammatory reaction, with no vital cells or bone cells, but some vascular penetration. We concluded that there was no bone deposition and no bone rehabitation. In group B, the initial segment was strongly fixed to the remaining mandible, there was an increase of the macroscopic dimension that paralleled the increase in the dimension of the remaining mandible and the growth of the animal. The cortical part had thinned down, the medullary part presented signs of bone deposition as well as bone resorption and vascular penetration. The periosteum from the adjacent normal mandible was growing and covering the frozen bone graft, offering additional stimulus to the bone deposition. In conclusion, the frozen bone graft acts as a normal bone graft. It needs to be placed in contact with vascularised bone and surrounded by well vascularised soft tissue to allow deposition of new bone. If the frozen graft is placed ectopically, it will be surrounded by chronic inflammatory reaction with no bone deposition.     

Inter-trabecular bone formation: a specific mechanism for healing of cancellous bone

Background and purpose — Studies of fracture healing have mainly dealt with shaft fractures, both experimentally and clinically. In contrast, most patients have metaphyseal fractures. There is an increasing awareness that metaphyseal fractures heal partly through mechanisms specific to cancellous bone. Several new models for the study of cancellous bone healing have recently been presented. This review summarizes our current knowledge of cancellous fracture healing.

Methods — We performed a review of the literature after doing a systematic literature search.

Results — Cancellous bone appears to heal mainly via direct, membranous bone formation that occurs freely in the marrow, probably mostly arising from local stem cells. This mechanism appears to be specific for cancellous bone, and could be named inter-trabecular bone formation. This kind of bone formation is spatially restricted and does not extend more than a few mm outside the injured region. Usually no cartilage is seen, although external callus and cartilage formation can be induced in meta­physeal fractures by mechanical instability. Inter-trabecular bone formation seems to be less sensitive to anti-inflammatory treatment than shaft fractures.

Interpretation — The unique characteristics of inter-trabecular bone formation in metaphyseal fractures can lead to differences from shaft healing regarding the effects of age, loading, or drug treatment. This casts doubt on generalizations about fracture healing based solely on shaft fracture models.     

Survival of massive allografts in segmental oncological bone defect reconstructions

Reconstructions of large segmental bone defects after resection of bone tumours with massive structural allografts have a high number of reported complications including fracture, infection and non-union. Our goal is to report the survival and complications of massive allografts in our patients. A total of 32 patients were evaluated for fracture, infection, non-union rate and survival of their massive allograft reconstructions. The average follow-up for this group was five years and three months. The total fracture rate was 13% with a total infection rate of 16%. We found a low union rate of 25%. The total survival of the allografts was 80.8% (± 18.7%) after five years. We found a five-year allograft survival of 80.8% which is comparable with other studies.

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Résumé  La reconstruction des larges pertes de substances osseuses après la résection des tumeurs osseuses par des allogreffes structurales est pourvoyeuse d’un pourcentage élevé de complications, telles que fractures, infections et pseudarthroses. Le but de notre étude est de rapporter la courbe de survie et les complications de ces allogreffes massives. 32 patients ont été évalués en terme de fractures, d’infections et de pseudarthroses, après mise en place d’allogreffes massives, le suivi moyen du groupe a été de 5 ans et 3 mois. le taux de fractures est de 13%, le taux d’infections de 16%. Nous avons trouvé un taux relativement bas de consolidation 25%. La survie de ces allogreffes, globalement est de 80,8% (± 18,7%) après 5 ans. le taux de survie de ces allogreffes à plus de 5 ans est de 80,8%, il est comparable aux autres études.

     

Effects of varying pulsatile lavage pressure on cancellous bone structure and fracture healing

OBJECTIVE: To study the effects of variations in pulsatile lavage irrigation pressure on the rate of new bone formation and the degree to which cellular elements are removed from cancellous bone after fracture. DESIGN: A previously described intraarticular fracture model was used for 29 New Zealand white rabbits that underwent osteotomy of the medial femoral condyle. Fractures were irrigated with high-pressure pulsatile lavage at a fixed distance and volume, but at nozzle pressures varying from 20 to 70 psi. Fractures were reduced and stabilized, and animals euthanized 14 days after fracture. Fluorescent bone staining was used to determine the rate of new bone formation in the osteotomy site. At the time of euthanasia, the nonoperated knees of 12 rabbits underwent osteotomy and irrigation using the same protocol. These specimens were sent for immediate scanning electron microscopy to determine the amount of cellular material removed from the bony trabeculae. RESULTS: In the first week after irrigation, there was no significant difference in the amount of new bone formation between the 20- and 30-psi groups, but there were significant differences between these groups and the 50- and 70-psi groups. There were no significant differences between any of the groups in the amount of new bone formed during the second week after irrigation. No structural damage to the bony trabeculae was observed in any specimen irrigated at any of the pressures used. There was a direct correlation between percentage of the trabecula completely cleared of cellular material and irrigation pressure; there were statistically significant differences between each of the groups. CONCLUSIONS: There are presently no recommended guidelines as to the optimal irrigation pressure, and this study is the first to address the effects of variations in pressure on bone healing. The results of this study indicate that early new bone formation in an intraarticular fracture rabbit model is inhibited by irrigation pressure of 50 psi or greater. Additionally, this study demonstrates a direct relationship between irrigation pressure and the amount of cellular material removed from the trabecula at the irrigation site. Surgeons should be aware of the potentially detrimental effects of using irrigation pressures at or above 50 psi in the treatment of fractures.