The fate of onlay membranous bone grafts in different facial recipient sites

The fate of onlay bone grafts was studied in the growing rabbit facial skeleton with regard to the depository and resorptive characteristics of bone surfaces. The nasal snout was chosen as the depository field and the vestibular surface of the mandibular ramus as the resorptive field. The membranous bone graft applied on a depository surface maintained its volume and morphology significantly better than the graft placed on a resorptive field. There was no evident difference between the fate of full-thickness and split-thickness membranous bone grafts in the different facial recipient beds. The authors suggest that the reconstructive procedures to improve the facial skeleton contour in growing children should be planned keeping in mind the depository or resorptive characteristics of the facial recipient site.     

膜状成骨与软骨成骨贴附移植后的组织学观察及骨计量学分析

目的深入探讨骨贴附移植后的变化及不同胚胎来源骨质（膜状成骨和软骨成骨）移植后的差异。方法应用新西兰兔、恒河猴采用荧光素双标记法,在不脱钙骨切片上,选用类骨质宽度、骨质矿化沉积率、荧光标记率等骨动力学指标对骨移植后的再生和改建进行计算机图像分析和定量测量。结果骨体积存留率：膜状成骨为（７８４±３５）％,软骨成骨为（５６±５１）％;骨矿化沉积率：膜状成骨为（３６０±０８）μｍ／ｄ,软骨成骨为（０９２±０３３）μｍ／ｄ;类骨质宽度;膜状成骨为（１４５６±２６９）μｍ,软骨成骨为（７３８±２２０）μｍ;荧光标记率：膜状成骨为（９１２２±２６９）％,软骨成骨为（５１２８±４１１）％。结论膜状成骨移植后较软骨成骨可保持更多的骨质体积,有更为明显的成骨再生能力且可诱导宿主骨成骨的能力不同,膜状成骨优于软骨成骨。     

Membranous bone healing and techniques in calvarial bone grafting

Membranous bone grafts have become an integral part of facial skeletal reconstruction. The convenience of harvesting the graft material from a single operative site was no doubt the reason for its initial utilization. In recent years membranous bone has been shown to be more resistive to resorption and perhaps even provide greater strength per unit volume than does its endochondral counterpart. These facts plus a relatively hidden, nonpainful donor site make membranous bone a desirable graft material. Grafts can be harvested in a variety of forms from dust to vascularized segments, totally dependent on the need. The various techniques of harvesting and methods of utilization are discussed. Rigid fixation has enhanced these techniques, and as the technical aspects improve, so do the results. The use of membranous bone has expanded from the field of congenital craniofacial surgery to the correction of traumatic facial deformities to purely aesthetic surgery. As more experience is gained, the utilization and indications for membranous bone grafting will continue to expand rapidly.     

膜状成骨与软骨成骨帖附移植后的组织学观察及骨计量学分析

OBJECTIVE: The experimental study was to determine the differences in changes in the onlay bone grafts of different embryonic origin. METHODS: The study was designed to compare the potential for appositional bone growth in membranous and endochondral onlay grafts in New-Zealand rabbits and a rhesus monkey. Results were assessed with volumetric measurement, histological examinations and stereologic analysis with double-fluorochrome labeling technique. RESULTS: For the membranous and endochondral bone grafts, the volumetric retention rate was (78.4 +/- 3.5)% and (56.0 +/- 5.1)% respectively. The mineralization apposition rate (MAR) was (3.6 +/- 0.8) microns/d and (0.92 +/- 0.33) micron/d; the osteoid seam width (OSW) was (14.56 +/- 2.69) microns and (7.38 +/- 2.20) microns; the tetracycline uptake rate(TUA) was (91.22 +/- 2.69)% and (51.28 +/- 4.11)%, respectively. CONCLUSION: 1. It was found that the membranous bone graft maintained its volume to a significantly greater extent than the endochondral bone graft; 2. Membranous bone grafts exhibited higher survival rate and greater activity than endochondral bone grafts; 3. Different changes were also found in the two recipient sites. There was more powerful bone regenerative reaction in the recipient bed of the membranous bone graft than the endochondral one.     

The healing of bone and cartilage

Transplantation of bone should be preceded by careful assessment of the recipient site. The function of the transplanted bone as an interposition graft, as an onlay graft, or in restoration or construction of a missing part of the skeleton must be considered. Cortical bone provides superior mechanical strength and can be incorporated with plate fixation to span interposition defects. Membranous bone used as onlay grafts for augmentation of craniofacial skeletal contour has been shown to be superior to endochondral grafts in maintaining volume. The use of rigid fixation to secure onlay grafts may eliminate the differences in resorption seen with membranous versus endochondral bone. The vascularity and quality of soft tissue at the recipient site may necessitate the use of vascularized bone or composite free tissue transfer. The calvarium is the most popular donor site for bone grafts used in craniofacial skeletal procedures. This membranous bone undergoes less resorption and revascularizes faster than endochondral bone. Cranial bone has excellent mechanical strength due to its large cortical component. The calvarial donor site causes less discomfort to the patient compared with rib or iliac crest, and the scar is well hidden. Harvesting and shaping cranial bone require special expertise, and there is potential morbidity. In cartilage transplantation, the surgeon must take into account the properties of viscoelasticity, the intrinsic balanced system of forces, and immunologic privilege. Cartilage deformed by an external force will tend to return to its original shape unless the deformation is maintained for several months. Surgical carving produces changes in the balance of intrinsic tensile and expansile forces, causing distortion in cartilage shape. Distortion can be minimized by carving in balanced cross-section. Carved cartilage grafts should be used for special indications in rhinoplasty. Autogenous cartilage is the framework of choice in ear construction. Composite grafts incorporating cartilage have been used successfully in eyelid reconstruction. Fresh autogenous cartilage is preferable to preserved allogeneic sources, as the latter undergo eventual resorption because there are no viable chondrocytes to maintain the matrix.     

膜内成骨与软骨成骨贴敷移植的早期血管化比较研究

目的采用 Wistar 大鼠对颅骨(膜内成骨)和髂骨(软骨成骨)贴敷移植后早期再血管化进行了观察研究。方法用计算机图像处理进行定量分析。结果骨移植7天后,软骨成骨与膜内成骨血管密度分别为:22.33%和11.88%;14天时分别为34.93%和15.93%。结论软骨成骨移植后较膜内成骨有更加迅速的血管化。文中对骨移植后骨质结构,血管化以及骨质体积存留之间的关系进行了讨论。     

膜内成骨与软骨成骨贴敷移植的早期血管化比较研究

目的 采用Ｗｉｓｔａｒ大鼠对颅骨（膜内成骨）和髂骨（软骨成骨）贴敷移植后早期再血管化进行了观察研究。方法 用计算机图像处理进行定量分析。结果 骨移植７天后,软骨 与膜内成骨血管密度分别为：２２．３３％和１１．８８％;１４天时分别为３４．９３％和１５．９３％。结论 软骨成骨移植后较膜内成骨有更加的血管化。文中地骨移植后骨质结构,血管化以及骨质体积存留之间的关系进行了讨论。     

膜内成骨与软骨成骨贴敷移植的早期血管化比较研究

目的采用Ｗｉｓｔａｒ大鼠对颅骨（膜内成骨）和髂骨（软骨成骨）贴敷移植后早期再血管化进行了观察研究。方法用计算机图像处理进行定量分析。结果骨移植７天后,软骨成骨与膜内成骨血管密度分别为：２２３３％和１１８８％;１４天时分别为３４９３％和１５９３％。结论软骨成骨移植后较膜内成骨有更加迅速的血管化。文中对骨移植后骨质结构,血管化以及骨质体积存留之间的关系进行了讨论。     

Absorption of onlay bone grafts in immature rabbits: membranous versus enchondral bone and bone struts versus paste

The absorption of onlay membranous and enchondral bone graft struts and paste was studied in immature New Zealand rabbits using a volume-displacement technique to determine the volume change in the grafts 8 weeks and 21 weeks after grafting. Membranous and enchondral bone paste does not survive as an onlay graft. Both enchondral and membranous bone graft struts undergo significant resorption (78% decreased volume in the enchondral grafts and 50% in the membranous bone grafts). These data support the clinical experience that both types of onlay bone grafts lose significant volume, and are in relative contradistinction to prior animal studies comparing membranous and enchondral onlay bone grafts.     

Microcirculation in grafted bone. A chamber technique for vital microscopy of rabbit bone transplants.

A method enabling in vivo observations of the microcirculation in orthotopically transplated bone in the rabbit is presented. The technique permits repeated study of a well-defined bone tissue compartment both before and after grafting to an autogenous or allogenous recipient site, respectively. It yields information about the reorganization of the microvascular system and the resorptive and formative processes of bone remodelling during incorporation of grafted bone. In the autologous experimental series, new capillaries were seen in the bone grafts 4 to 5 days after transplantation. No re-utilization of pre-existing graft vessels was observed.     

Microcirculation in Grafted Bone:A Chamber Technique for Vital Microscopy of Rabbit Bone Transplants

A method enabling in vivo observations of the microcirculation in orthotopically transplated bone in the rabbit is presented. The technique permits repeated study of a well-defined bone tissue compartment both before and after grafting to an autogenous or allogenous recipient site, respectively. It yields information about the reorganization of the microvascular system and the resorptive and formative processes of bone remodelling during incorporation of grafted bone. In the autologous experimental series, new capillaries were seen in the bone grafts 4 to 5 days after transplantation. No re-utilization of pre-existing graft vessels was observed.     

The long-term survival of onlay bone grafts--a comparative study in mature and immature animals

Onlay bone grafting was studied with regard to age of the animal and type of bone graft used (membranous bone or endochondral bone with or without periosteum, and decalcified homograft). The bone grafts were placed in the nasal dorsum in a group of mature and immature New Zealand rabbits. Volume displacement studies were carried out. Graft survival was greatest in membranous bone and least in endochondral grafts. There was significantly greater absorption of endochondral grafts in immature animals than in the mature group. Presence or absence of periosteum did not make a significant difference in graft survival.     

Orthotopic liver allografts in the rat. The influence of strain combination on the fate of the graft

This report describes the fate of orthotopic liver allografts performed in 22 donor/recipient strain combinations. Of these, 2 were major histocompatibility complex (MHC)-congenic, 18 were fully allogeneic, and 2 were non-RT1 incompatible combinations considered to differ only in minor transplantation antigens. The fate of fully allogeneic liver grafts was strictly dependent on the donor/recipient strain combination, and survival times fell into three nonoverlapping groups corresponding to acute rejection (8-21 days), delayed rejection (28-63 days), and prolonged survival (greater than 100 days). Serial levels of recipient serum enzymes also fell into groups corresponding to the fate of the graft. In 7 fully allogeneic donor/recipient combinations, liver grafts showed very prolonged survival. In five combinations they were rejected almost as quickly as kidney or heart grafts. In the two MHC congenic combinations, liver grafts survived for prolonged periods. In the non-RT1-incompatible combinations, unexpectedly, PVG livers were rejected by AUG recipients. MHC-incompatible liver grafts of a given strain survived for long periods or were rejected (in acute or delayed fashion) depending on the recipient strain. This behavior is unique to liver amongst commonly transplanted vascularized organs, and the fate of the graft clearly indicates strain-dependent levels of recipient responsiveness to defined transplantation antigens. Independent evidence supporting this conclusion is discussed. Apparently anomalous results of liver grafting in certain strain combinations are briefly considered.     

Gradual graft-cell repopulation with recipient cells following vascularized bone and limb allotransplantation

Little is known about the fate of graft cells following vascularized bone allografting. This study was conducted to define the process of graft-cell repopulation with recipient cells. Sixty-five vascularized tibial bone and 50 limb allotransplantations were performed in rat sex-mismatched pairs. FK 506 was used for immunosuppression. The ratio of donor and recipient cells in the graft was evaluated by semiquantitative polymerase chain reaction, using the Y-chromosome primers. Allografted bones had no rejection episodes. In the vascularized bone allograft model, donor-derived cells were gradually replaced by cells of recipient origin, such that by 24 weeks, they comprised only 10% of total cells. In the limb allograft model, male recipient cells were detected in female grafts not at 1 week but at 48 weeks posttransplantation. The ratio of recipient cells was more than 10% in the femur and tibia. Recipient-derived cells gradually migrated into the grafted bone cells with the passage of time.     

自体颅骨外板、下颌骨外板整复颅颌面创伤后继发鼻畸形

目的　探讨自体颅骨外板、下颌骨外板移植在颅颌面创伤后继发鼻畸形矫正中的应用。方法　 1997～ 2 0 0 2年我们对 4 4例颅颌面创伤合并鼻畸形患者 ,运用颅颌面外科诊断和手术技术 ,为其恢复颅颌面骨性轮廓结构 ,同时运用自体颅骨外板或下颌骨外板移植重建鼻支架矫正鼻畸形。结果　所有病例伤口均一期愈合 ,治疗效果满意。经 6个月～ 2年随访观察 ,无感染、无鼻背皮肤红肿坏死、支架无外露及移位 ,骨吸收不明显 ,供区无并发症发生。结论　自体颅骨外板、下颌骨外板采取方便 ,切口隐蔽 ,并发症少 ,特别适用于外伤后严重鼻畸形的矫正 ,是一种理想的移植材料。     

Technique of organ removal and fate of kidney grafts from liver donors.

The fate of 42 kidney grafts taken from heart-beating, ventilated donors at the same time as removal of the liver for allografting is reported, and is compared with 50 kidney grafts taken from heart-beating, ventilated donors whose ventilators were electively switched off either during or immediately before kidney removal. The fate of 32 kidney grafts taken from donors classified as "dead on arrival" at the admitting hospital is also reported. Onset of life-supporting graft function was significantly earlier among kidneys from the "liver donor" group. Consequently, immediate postoperative dialysis requirements were significantly less in recipients of this group of kidneys. Early graft survival, the incidence of graft primary nonfunction, failure of first and second kidney grafts, and recipient survival were not significantly different when comparing liver donor and "ventilator switch off" kidneys. No constant relationship was apparent in any donor group between graft fate and the anoxic and ischaemic times the graft was exposed to during organ removal and reimplantation.     

Bone graft incorporation after cortical perforations of the host bed

A fundamental issue in onlay bone graft persistence is the unpredictable extent of incorporation and volumetric maintenance of the graft. The purpose of this study was to evaluate the effects on integration of onlays, with either their cancellous or cortical portion facing toward the host bed, positioned over cortical perforations at the recipient site. Tibial or femoral unicortical bone grafts were harvested from isogeneic donors and positioned subperiostally on each tibia of 22 adult Lewis rats. On the experimental side, the recipient outer cortical bone surface received multiple perforations, 0.25 mm in diameter. The contralateral side served as a control (no cortical perforations). The findings were assessed after 4 and 20 weeks using routine histologic and immunohistochemistry techniques. Cortical perforations induced a migration of the recipient bone marrow into the graft as well as a reduced size diminution. More cortical bone remodeling and marginal lamellar bone apposition were observed after orientating the cortical portion of the graft toward the recipient site. These observations may be useful clinically to improve long-term success after autogeneic bone grafting. (Otolaryngol Head Neck Surg 1997;117:664-70.)     

Superficial skin texture: a study on full-thickness skin grafting in facial reconstruction

Usually in harvesting a full-thickness skin graft, we match color, skin thickness, and the presence of hair in the potential donor site with the recipient site to obtain as good an esthetic result as possible. Superficial skin texture is, in part, responsible for the esthetic result in facial reconstruction. Full-thickness skin grafts harvested from the supraclavicular region in 20 patients operated on for facial skin tumors and immediate reconstruction, were included in this study. The superficial skin texture was reproduced using a silicone cast technique; a polyvinylsiloxane derivative was used and it was analyzed by scanning electron microscopy (SEM) in order to detect and measure morphological features of the skin surface. The mechanism affecting superficial skin texture was studied to elucidate the importance of the superficial skin texture of the graft donor site and consequently the intraoperative orientation of the graft into the recipient area to improve the esthetic outcome. Our study shows that the forces of the recipient site are able to modify full-thickness skin graft dermis and as a result change the overlying superficial skin pattern. The graft always tends to change to the features of the recipient area after 24 months because of the environment of the new site. These findings suggest that color and thickness of the donor site still remain more important than intraoperative graft orientation in the recipient area in order to achieve good esthetic results in skin grafting.     

自体颅骨移植在眶底重建中的应用

目的 评价自体颅骨移植在治疗面部外伤致眶底缺损中的作用。方法 对34例面部创伤眶底爆裂骨折（以下简称眶底骨折）有骨质缺损者,采用冠状切口取自休遭受,结膜切口加外眦切开入路进行骨移植修复缺损。结果 所有病例术后创口愈合良好,无感染。供骨区无并发症发生。1例术后3个月内有轻微下睑外翻,通过自行按摩半年后已不明显,8例术前有眶下区麻木者,术后1-6个月全部恢复,4例有复视者术后消失,通过半年至5年（平衡11个月）的随诊,移植骨成活良好,供受骨区切口瘢痕不明显,均取得了满意的临床疗效。结论 自体颅骨移植并发症少,对眶底的重建有许多优点。是眶底重建的理想移植材料。     

Donor marrow-derived cells as immunogens and targets for the immune response to bone and skin allografts

The relative importance of donor marrow-derived cells in the immunogenicity of bone and skin allografts was compared. Radiation chimeras were created to have marrow-derived cells (MDCs) of a different genotype from their nonmarrow-derived cells (NMDCs). Such animals were used as donors of bone or skin for recipients chosen so that either the MDCs or the NMDCs of the graft would be incompatible. Immunogenicity was determined by measuring the recipient antibody response. The effect of the immune response on the bone graft (rejection) was determined by impaired bone healing. When MDCs alone were H-2 disparate with the recipient, bone grafts were immunogenic, and the bone graft healing was impaired. In contrast, skin grafts in the same combinations were immunogenic but were not rejected if the differences were only expressed on the MDCs of the graft. The role of NMDCs in all of these experiments was more difficult to interpret, but the results suggested that NMDCs are relatively unimportant for healing of bone grafts, although critical for rejection of skin grafts. We conclude that, unlike the situation with skin grafts, the major inducers and targets of the immune response to bone allografts are marrow derived.