Biomechanical properties of heat-treated bone grafts

Introduction A possible critical complication associated with banking bone is human immunodeficiency virus (HIV) infection. Recently, since the report of HIV infection in bone allografts from an HIV-seronegative donor, a more reliable method of sterilization for preserved bone graft has become necessary. Heat treatment of banking bone is one of the simple sterilization methods. This method is especially safe and practical for the prevention of HIV infection.Materials and methods We previously reported a biological study on heat-treated bone graft. In that study, we showed that revascularization and new bone formation of bone graft after heat treatment at 60°C was nearly the same as that of non-heat-treated bone graft, while at 100°C, revascularization and new bone formation showed a significant delay. This time, we examined the change of mechanical strength of heat-treated bone grafts after transplantation in an experiment. To eliminate the problem of antigenicity of grafted bone, we used autografts, not allografts. Two types of heat-treated autografts were employed: heat-treated at 60°C for 30 min and heat-treated at 100°C for 5 min; as a control, fresh autografts were replaced in the left femur of rabbits. A strength test was performed for both the transplanted bone and the untreated intact right femur with time after transplantation. The strength test consisted of a compression test and torsional test, and the strength was compared between transplanted bone and the untreated intact right femur.Results In the compression test, the grafts heat-treated at 60°C showed a strength ratio before transplantation of 97.3%. The strength ratio decreased to 63.5% at 18 weeks after transplantation. Then the strength ratio increased and recovered to 94.5% at 48 weeks after transplantation. However, the grafts heat-treated at 100°C showed unsatisfactory mechanical strength, at 48 weeks the strength ratio was 60.1%, which was significantly lower compared with controls. In the torsional test, the grafts heat-treated at 60°C showed almost the same strength observed in the compression test. However, the grafts heat-treated at 100°C showed unsatisfactory mechanical strength: at 48 weeks, the strength ratio was 57.3%.Conclusion Therefore, heat treatment at 60°C is a useful sterilization method, not only in biological but also mechanical terms.     

Quantitative analysis of revascularisation and new bone formation in experimental bone grafts

Summary Revascularisation and new bone formation in bone grafts has been extensively studied by histological techniques, but the images obtained are very complex and consequently difficult to evaluate quantitatively. We report similar analyses in experimental bone grafts using newer computerised digital techniques. Fresh autografts and fresh and frozen allografts were used. The histological analogue images from them were input digitally into an image processor. The amount of revascularisation and new bone formation could then be quantified in the different grafts. This system has proved to be a useful method of evaluation which could be applied to the quantitative analysis of other histological images.

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Résumé La revascularisation et la formation d'os nouveau dans les greffes osseuses ont été étudiées en détail par les techniques histologiques. L'information analogique fournie par les images histologiques est cependant difficile à évaluer quantitativement, car ces images sont très complexes. Dans cette étude nous avons analysé quantativement la revascularisation et la formation d'os nouveau, au cours de greffes expérimentales, en utilisant les techniques les plus récentes d'ordinateurs numériques. Trois sortes de greffes ont été utilisées: l'autogreffe fraîche, l'allogreffe fraîche et l'allogreffe congelée. Les images histologiques analogiques de ces greffes ont été introduites numériquement dans un processeur d'images puis analysées. Ainsi nous avons pu quantifier la revascularisation et la formation d'os nouveau dans ces différents types de greffes. Cette étude montre que cette méthode est très utile pour évaluer la revascularisation et la formation d'os nouveau et qu'elle peut aussi être appliquée à l'analyse d'autres images histologiques.

     

Combination of proplast and periosteal grafts for new bone formation

Summary An experimental model is presented to examine the possibility of combining a porous alloplastic implant, Proplast, and periosteal grafts in rabbits to produce a semi synthetic bone graft. Our aim was to use the Proplast implant as a scaffold for bone ingrowth from the periosteal grafts, achieving initial mechanical stability and control over the final shape of the new bone. Fibrous tissue ingrowth into the Proplast occurred, with very little bone ingrowth from the periphery. The addition of periosteum did not alter the results. It seems that the size of the pores in Proplast did not allow bone ingrowth.Supported in part by a grant from the joint research fund of the Hebrew University and Haddasah, and the Frederick Kornfeld Fund     

Remodelling and healing process of moderately heat-treated bone grafts after wide resection of bone and soft-tissue tumors

Introduction In the reconstruction of extensive bone defects after massive resection of malignant musculoskeletal tumors, the clinical results of moderately heat-treated autogenous bone graft have rarely been documented. We evaluated the remodelling and healing process of moderately heat-treated autogenous bone graft by means of imaging features.Materials and methods The subjects of this study were 19 patients with bone and soft-tissue tumors treated by heat-treated bone graft at our institution between 1992 and 2001, the mean follow-up period was 4.8±2.8 years (range 1–9 years). The remodelling and healing process of heat-treated bone graft was evaluated by means of radiography, bone scintigraphy, and MRI.Results The mean period to obtain bone union between host bone and grafted bone was 9.4 months. Infection was noted in 1 patient, and fracture was present in 2 patients. In 6 patients, pseudoarthrosis was found. Bone scintigraphy showed an increased uptake at the host-graft junction in the period between 3 and 36 months (median 10.7 months) postoperatively. A gradually increased diffuse uptake on the grafted side was evident at an average of 29.1 months (range 19–41 months) postoperatively. High signal intensity on T2-weighted images was observed in the early period after surgery, and iso-intense or low signal intensity became evident after an average of 28.3 months. A gradually increased diffuse uptake on scintigraphy and iso-intense or low signal intensity on T2-weighted images indicated remodelling of the grafted bone.Conclusion Bone union of a moderately heat-treated autogenous bone graft was noted at about 9 months, and its remodelling was proceeding at about 30 months. This method will be useful for bone defects after massive resection of soft-tissue and bone tumors.     

Revascularization of isolated autologous bone grafts following microsurgical implantation of arteries and veins

The microsurgical implantation of a saphenous vascular axis into free transplanted autologous isolated rib segments in Beagle dogs led to complete revascularization of the bone after two, three and four weeks. Indian ink and Mercox-injected specimens showed a vascular network which penetrated the entire cortical layer. Semi-thin sections revealed osteoblasts and osteoclasts visible in the canals of the revascularized cortical layer, while the control specimen without vessel implantation showed nothing but ground substance. The revascularized bones did not contain any necrotic areas. The newly formed vascular system consisted of arteries, veins and their anastomoses. The veins appeared to produce a greater number of new vessels than the arteries.     

Revascularization of isolated autologous bone grafts following microsurgical implantation of arteries and veins

Summary The microsurgical implantation of a saphenous vascular axis into free transplanted autologous isolated rib segments in Beagle dogs led to complete revascularization of the bone after two, three and four weeks. Indian ink and Mercox-injected specimens showed a vascular network which penetrated the entire cortical layer. Semi-thin sections revealed osteoblasts and osteoclasts visible in the canals of the revascularized cortical layer, while the control specimen without vessel implantation showed nothing but ground substance. The revascularized bones did not contain any necrotic areas. The newly formed vascular system consisted of arteries, veins and their anastomoses. The veins appeared to produce a greater number of new vessels than the arteries.     

Preservation of bone morphogenetic protein in heat-treated bone.

In operations of bone tumors, reimplantation of resected bone after boiling or autoclaving is a simple means of obtaining both tumor necrosis and skeletal reconstruction. However, such reimplants lose their osteogenesity. We investigated whether bone inductive ability could be maintained in heat-treated bone. Bone morphogenetic protein (BMP) extracted from rabbit bone after heating for various periods at different temperatures was implanted into the muscles of mice to evaluate osteogenetic activity. The maximum new bone formation was observed in specimens treated at 70 degrees C for 10 minutes, followed by those treated at 70 degrees C for 15 minutes. We then measured the temperature in the center of a cortical bone heated in 0.15 N NaCl solution at 50 degrees, 60 degrees, 70 degrees, 80 degrees, and 90 degrees C. Cortical bone center temperature reached that of the surrounding solution within 2.5 minutes. These results indicated that heating at 70 degrees for 10 to 15 minutes was suitable for heat treated-bone to maintain bone inductive ability.     

The new bone formation and bone metabolism in Forestier disease

The study was performed on 36 male patients between 65 and 83 years who were either hospitalised or treated in the out-patients clinic due to Forestier's disease. The aim of the study was to evaluate the advance of ectopic bone formation process in cervical spine and bony metabolic changes in treated patients. The study showed reverse corelation between the degree of advance of cervical hyperostosis and the prevalence of osteoporosis and metabolic disorders in the tested group. The authors have emphasized the need of precise evaluation and differentiation of Forestier's disease and degenerative spine disease.     

Revascularization of nerve grafts: an experimental study

The time course of revascularization of grafted nerves, and the possible dependence of this revascularization on the length of the graft are two related questions that are addressed. Survival of Schwann cells in the nerve graft and a timely revascularization must be seen as a precondition for an optimal regeneration process. The revascularization process after different postoperative intervals is demonstrated in the sciatic nerve of rabbits by the use of microangiography, with Roentgen-positive water-soluble contrast medium. The third postoperative day is the earliest point in time for revascularization of the autologous graft from surrounding tissues. On the fourth postoperative day, a hyperemia with extension to all sides of the intraneural vessel system exists that still persists on the fifth and sixth days. In one experimental group, revascularization was allowed to occur only in a longitudinal direction. Revascularization under these conditions proved to be poor, slow, and obviously dependent on the length of the graft. Survival and subsequent function of free autologous nerve grafts may depend on the diameter of the grafts and the quality of the recipient site, but not on the length of the grafts, when timely revascularization from the surrounding tissues is present.     

血管束骨内移植重建离断骨血液循环的实验研究

为了研究离断骨在一定应力状态下植入血管束后，能否重建骨的血液循环以及血管束移植对成骨的影响，作者将１８只成年杂种犬胫骨两端截断，切除实验骨区的骨膜，胫骨离断面填入硅胶膜以阻断两侧干骺端血供，将离骨段固定于原位；分离出胫前动静脉束并结扎。随机分成３组，实验Ａ组（ｎ＝７）：结扎后的血管直接植入骨髓腔；Ｂ组（ｎ＝７）：血管束打孔后植入骨髓腔；Ｃ组（ｎ＝４）：离断后的胫骨段内不植血管，作为对照。术后分别于不同时间进行血管造影、血管筑型、大体及组织学和电镜观察。实验结果显示：原实验骨因初期缺血均发生无菌性坏死；在一定应力状态下，血管束骨内移植后，植入的血管再生旺盛，骨髓腔内成骨活跃。结果表明，血管束骨内移植后可重建坏死骨的血液循环，膜性化骨和软骨内化骨在成骨因素中均发挥着重要作用。     

Revascularization and ligamentization of autogenous anterior cruciate ligament grafts in humans

Forty-eight patients were enrolled in a study to determine the time interval for maturity and remodeling following arthroscopically assisted autogenous anterior cruciate ligament reconstruction (ACLR). Two biopsy specimens, one superficial and one deep, at the same level in the midsubstance of the ACL were obtained. Graft age, time from ACL reconstruction to biopsy, ranged from 3 months to 120 months. The patients were placed into four groups, (1) 3 to 6 months, (2) 7 to 12 months, (3) more than 12 months, and (4) control, in accordance with the time following ACL reconstruction. Each specimen was independently evaluated using light microscopy by two different observers in a blinded design. The biopsy specimens were evaluated for vascularity, cellularity, fiber pattern, and metaplasia when compared with the normal ACL. None of the patients was protected from activity as a result of ligament biopsy and no adverse outcomes were reported as a result of biopsy. Our study showed that fiber pattern, cellularity, vascularity, and degree of metaplasia obtained gross histological similarity with a normal ACL by 12 months after autogenous reconstruction. Unexpectedly, no significant statistical differences were noted for all grafts more than 6 months after ACLR, for two of the histological features studied, vascularity and fiber pattern, P=.05. We conclude that by 12 months after autogenous ACLR, graft maturity resembles a normal ACL. Additionally, because no statistical differences were noted in vascularity and fiber pattern after 6 months following autogenous ACLR, significant graft maturity may occur before 12 months. This may allow early postoperative return to full activity and support proponents of accelerated rehabilitation programs following autogenous ACLR.Arthroscopy 1998 Mar;14(2):197-205     

应用受者脾动脉重建移植肝动脉

目的探讨应用受者脾动脉重建移植肝动脉的方法。方法回顾性分析1999年5月至2005年7月完成的328例次原位肝移植中的肝动脉重建方法。其中7例受者因肝总动脉不适宜吻合而采用脾动脉重建移植肝动脉。7例受者均为男性,平均年龄(42.5±11.3)岁。肝移植术中,于胰腺体部上缘处游离受者脾动脉干2cm,结扎其远端,利用其近心端与供肝肝总动脉对端吻合;在2.5倍手术放大镜下,以7-0Prolene缝线连续缝合方式完成动脉重建。结果术后行间断彩色多普勒超声扫描监测显示:7例受者肝动脉血液供应良好,无血栓形成,无胆系并发症发生,无脾脏梗死征象。2例肝细胞癌患者分别在术后18、21个月死于癌肿复发,5例良性肝病患者术后随访22.6个月(12~38个月),肝功能良好,1年生存率为100%。结论在肝移植受者肝总动脉不适宜重建移植肝动脉时,选择性应用受者的脾动脉是简便可行的动脉重建方式。     

Soft-tissue haemangioma and periosteal new bone formation on the neighbouring bone

Deeply situated soft-tissue haemangioma sometimes causes periosteal new bone formation on the neighbouring bone. The purpose of this study was to elucidate the aetiological factors for this phenomenon. We studied 25 patients with soft-tissue haemangioma on whom plain radiographs and computed tomography (CT) and/or magnetic resonance imaging (MRI) examinations were performed. We examined the presence or absence of periosteal new bone formation, haemangioma-bone distance, size of haemangioma and pain. Periosteal new bone formation was seen in 12 of 25 patients. In these 12 patients, the haemangioma was adjacent to the bone in 11 patients, while the haemangioma-bone distance was 4 mm in the other patient. In the remaining 13 patients who had no periosteal new bone formation, the haemangioma-bone distance was 5–27 mm. Pain in the former group was stronger than that in the latter group, the difference being statistically significant. There was no statistically significant difference in size of haemangioma between the two groups. Therefore, the main factor that induces periosteal new bone formation on the neighbouring bone was not the size of haemangioma, but the distance between the haemangioma and the bone. Received: 11 January 2001