骨关节节段性缺损的修复与重建

随着医学科学的发展 ,骨肿瘤保肢治疗广泛应用 ,瘤段切除以及因严重感染、创伤造成的骨关节的节段性缺损的修复与重建越来越受到矫形外科医生的重视。下面将近年来修复骨关节节段性缺损的方法及效果综述如下。1　应用人工材料修复和重建骨与关节节段性缺损彭德清等 〔1〕用氧化铝陶瓷纯刚玉与多孔羟基磷灰石烧结成复合人工骨 ,修复狗股骨大段缺损 ,其假体为管状 ,内层为氧化铝陶瓷纯刚玉 ,外层为多孔羟基磷灰石 ,结果术后 2 4周新生骨包绕整个假体 ,通过长入孔隙的骨质与假体完全融合 ,无松动、折断现象 ,认为内层氧化铝陶瓷纯刚玉生物力学…     

定制化单侧膝关节假体设计与快速制造方法研究

目前人工假体的制造还难以达到个体适配化，尤其是带有关节面的半关节，能否与对侧正常关节软骨完全匹配是决定手术治疗成败的关键。本文以临床影像学资料为数据源，应用逆向工程和快速原型技术相结合制作出与人体膝关节面形状完全相匹配的人工假体原型，而后利用传统的制作工艺完成假体关节面及其连接结构的最终成型。结合异体骨移植术，将该项研究结果成功地用于股骨下段肿瘤患者，临床资料显示该假体能够与患者对侧关节面良好匹配，患者关节功能恢复较理想。该方法可实现替换关节面和对侧面的匹配，而且假体制造的周期短、成本低，可实现个体定制化，为探索半关节置换及临床提供了制造方面的技术保障。     

定制式人工全髋假体设计制造及临床应用

延长人工关节的有效使用寿命是人工关节研究的关键,而骨吸收和无菌性松动是影响其使用寿命的主要因素。由于人体的绝对个性化特点,标准人工假体与病人骨骼之间的误差使二者难以很好匹配,不能确保人工关节的长期稳定。同时,一些病人骨骼呈先天性畸形或由于骨骼病变造成骨与关节大面积损坏,其骨骼关节与正常情况明显不同,亦不可能选用标准人工假体。计算机辅助设计和制造(Com puter aided design/ Com puter aidedmanufacture,CAD/ CAM)通过对病人骨骼的三维重建,为每一位病人进行特殊设计和制造,提高了假体与病变骨骼的匹配度,提高了人工关节的长期稳定性,有效防止了关节松动。本文对CAD/ CAM定制式人工髋假体的优点、设计制造、临床应用及有待解决的问题进行了介绍     

定制型人工髋假体研究应用

假体松动是目前导致人工髋部假体置换术失败的主要原因。人类股骨上段骨髓腔大小形状差异显著,以致通常设计的髋假体柄在多数情况下不能与骨髓腔形成解剖匹配,接触面小,假体-骨界面应力分布不合理,显著影响假体-骨结合面的稳定性。近几年,按人配制的定制型人工髋假体的研究应用已受到重视。本文介绍发展定制型人工髋假体的依据、定制型人工髋假体的设计研究与临床应用以及定制型假体尚有待解决的问题。     

标准截面形状定制型股骨柄假体设计

目的 介绍一种标准截面形状定制型股骨柄假体结构以及自行开发的设计方法。方法首先利用DICOM格式的患者股骨CT图像,重建患者股骨近端模型;根据重建出的患者股骨近端模型构建股骨柄假体匹配段矩形的截面边界,并在矩形截面边界内用简单的线条初步构建出假体的截面轮廓曲线;利用股骨近端模型对初步设计出的股骨柄假体进行验证,并通过调整设计参数使最终设计出的个性化股骨柄假体与患者股骨髓腔相匹配。结果 定制型人工髋关节股骨柄假体采用标准截面形状,便于快速设计出个性化假体,而且设计操作简单。参数化程序设计大大降低了个性化股骨柄假体的设计工作量。结论 标准截面形状定制型股骨柄假体的设计将有助于提高定制型人工髋关节置换手术的成功率,促进定制型股骨柄假体在临床上的应用,进一步提高患者的生活质量。     

一种组合式个性化人工膝关节假体数字化设计方法

目的 提出一种组合式个性化人工膝关节假体结构,解决膝关节股骨肿瘤保肢手术由于截骨位置差异性较大,很难采用标准型人工膝关节假体满足个性化需求的问题。方法 首先将患部关节区域CT数据进行三维重建,并利用MRI增强扫描技术建立肿瘤的三维模型,再通过肿瘤模型与患部关节模型进行位置匹配,在三维模型上确定手术截骨位置,根据截骨尺寸设计个性化的股骨柄与标准股骨髁假体进行有效组合,形成一种组合式个性化人工膝关节假体。结果 根据本文设计方法的结果加工成型,骨科临床医生分析膝关节假体结构与人体膝关节生理结构相符,达到个性化假体设计要求,能够重建患者膝关节功能。结论 这种膝关节假体结构有利于降低个性化膝关节假体设计加工成本,缩短设计加工周期,有望提高患者生命质量。     

一种具有微观仿生结构的定制化下颌骨植入体

为了使下颌骨人工植入体具有定制化的外形，并使其具有一定的生物活性及与人骨内部哈弗氏管和福克曼管类似的三维微观通道，提出了利用快速原型制造仿生下颌骨替代物的方法。该方法首先利用快速原型技术快速准确地制作出与人骨形状相匹配的人工植入体(模型)及内部三维仿生网架，而后运用铸钛技术完成植入体钛框架的最终成型，钛网内的三维仿生网架被复合有骨形态发生蛋白的磷酸钙骨水泥所包绕。该项研究结果不仅利用快速原型制作出仿生下颌骨人工植入体，还成功地投入临床应用。结论：虽然仅以下颌骨为例，但快速原型适宜于所有仿生人工植入体的定制化制造。     

少年儿童膝关节恶性骨肿瘤切除后的重建方法

少年儿童膝关节周围恶性肿瘤切除后的重建是广大骨肿瘤科医生面临的棘手难题。由于股骨下端和/或胫骨上端恶性肿瘤切除时连同骨骺一起切除,由此造成的肢体不等长及肢体功能障碍等问题一直困扰着患者及家属。随着化疗及外科技术的不断发展,少年儿童膝关节恶性肿瘤的保肢治疗成为主要的治疗方式,重建方法主要包括瘤骨壳灭活再植、3D打印金属假体重建大段骨缺损、半关节假体置换、非铰链型儿童全膝关节假体和可延长假体。本文针对该课题近年的研究进展进行回顾总结,以期帮助广大骨肿瘤科医生全面提高认识并指导临床诊疗。     

生物活性人工骨结合CAD/CAM技术重建颅骨板制作系统

目的 通过CAD／CAM技术和快速成型技术并结合生物活性人工骨材料的应用，建立个性化设计制造具有良好骨融合性的颅骨板制作系统。方法 通过螺旋CT扫描、CAD三维重建成像、快速成型机加工，制成与患者颅骨缺损部位几何形态相同的个性化实体模型，应用石膏翻模工艺和EH复合人工骨材料，制成患者骨修补治疗用颅骨板。结果 CAD／CAM技术重建的人工骨颅骨板几何外形与骨缺损部位非常吻合，与健康侧对称，临床效果非常满意。结论 生物活性人工骨结合CAD／CAM技术重建颅骨板制作系统为治疗颅骨缺损患者提供了一种新手段，可有效提高临床治疗效果和修复美学效果。     

3D打印个性化定位截骨导板在人工全膝关节置换术中的精准度研究

目的基于3D打印技术构建全膝关节置换术(TKA)的个性化定位截骨导航模板(POI),并对POI的精准度进行评价。方法术前对患侧下肢行全长CT扫描,膝关节MRI扫描,匹配膝关节CT及MRI数据,重建具有软骨层的下肢全长三维解剖数据。在CAD软件中测量下肢力线、模拟截骨、虚拟个性化安装TKA假体,再依据CAD设计结果,采用Boolean Subraction运算设计POI与股骨髁、胫骨平台的配准面,并根据配准面、截骨面,设计POI的外形与限位结构,最终采用FDM 3D打印技术制作POI。制作股骨髁POI及胫骨平台POI各15例,比较POI尺寸、截骨槽大小的设计值和实际值的偏差以测量POI的构建精准度;比较POI匹配点与解剖标志点距离(DML)实际值和理论值的偏差以测量POI的匹配精准度;测量术后TKA假体角度与设计值的偏差值以验证POI的截骨精准度。结果 POI的外形、限位结构与设计值差异无统计学意义(P0.05);实际股骨髁与胫骨平台POI的DML与理论值差异无统计学意义(P0.05);术后TKA假体的各特征角度与设计值差异无统计学意义(P0.05)。结论 3D打印技术可以准确构建TKA的POI,POI可以准确地配准关节面并导向TKA术中截骨,有利于TKA手术的精准化。     

Mechanical evaluation of a porous bone graft substitute based on poly(propylene glycol-co-fumaric acid)

A porous, resorbable polymer composite based on poly(propylene glycol-co-fumaric acid) (PPF) was mechanically evaluated in vitro for use as a bone graft substitute and fracture fixative. The test material created a dynamic system capable of initially providing mechanical integrity to bony voids and a degradative mechanism for ingrowth by native bone. The unsaturated polymer, PPF, was crosslinked in the presence of effervescent agents to yield a porous microstructure upon curing. An in vitro degradation study first assessed the temporal mechanical properties of the test material. This research was followed by an ex vivo study using a long-bone osteotomy model to characterize the mechanics of fixation. Results showed the initial compressive strength of the cross-linked PPF system was comparable to cancellous bone. The rate of strength loss was commensurate with the predicted mechanical recovery of healing bone with analogous results in a composite that comprised also 25% (by weight) autograft. Mechanical testing in the long-bone model demonstrated that PPF-based bone-graft substitute increased the flexural strength of K-wire stabilized osteotomies. These results suggest that this type of bone graft substitute may have clinical utility in the stabilization of complex tubular bone fractures.     

Architecture and properties of anisotropic polymer composite scaffolds for bone tissue engineering

Bone is a complex porous composite structure with specific characteristics such as viscoelasticity and anisotropy, both in morphology and mechanical properties. Bone defects are regularly filled with artificial tissue grafts, which should ideally have properties similar to those of natural bone. Open cell composite foams made of bioresorbable poly(L-lactic acid) (PLA) and ceramic fillers, hydroxyapatite (HA) or beta-tricalcium phosphate (beta-TCP), were processed by supercritical CO2 foaming. Their internal 3D-structure was then analysed by micro-computed tomography (microCT), which evidenced anisotropy in morphology with pores oriented in the foaming direction. Furthermore compressive tests demonstrated anisotropy in mechanical behaviour, with an axial modulus up to 1.5 times greater than the transverse modulus. Composite scaffolds also showed viscoelastic behaviour with increased modulus for higher strain rates. Such scaffolds prepared by gas foaming of polymer composite materials therefore possess suitable architecture and properties for bone tissue engineering applications.     

Novel polymer-synthesized ceramic composite-based system for bone repair: an in vitro evaluation

The emergence of synthetic bone repair scaffolds has been necessitated by the limitations of both autografts and allografts. Several candidate materials are available including degradable polymers and ceramics. However, these materials possess their own limitations that at least in part may be overcome by combining the two materials into a composite. Toward that end, a novel approach to forming a polymer/ceramic composite has been developed that combines degradable poly(lactide-co-glycolide) microspheres and a poorly crystalline calcium phosphate that is synthesized within the microspheres, which are then fused together to form a porous three-dimensional scaffold for bone repair. The design, fabrication, and characterization of the composite microspheres, the calcium phosphate formed within these microspheres, and the formation of scaffolds were studied. The calcium phosphate formed was analyzed by x-ray diffraction, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy, and was shown to be similar to native bone in both composition and crystallinity by controlling certain processing parameters such as mixing time, solution pH, and mixing temperature. Scaffolds with porous interconnected structures and mechanical properties in the range of trabecular bone were fabricated via precise control of polymer/ceramic ratios within the microspheres and scaffold heating times. This composite scaffold represents a new and important vehicle for bone-tissue engineering.     

Personalized implant for high tibial opening wedge: combination of solid freeform fabrication with combustion synthesis process

In this work a new generation of bioceramic personalized implants were developed. This technique combines the processes of solid freeform fabrication (SFF) and combustion synthesis (CS) to create personalized bioceramic implants with tricalcium phosphate (TCP) and hydroxyapatite (HA). These porous bioceramics will be used to fill the tibial bone gap created by the opening wedge high tibial osteotomy (OWHTO). A freeform fabrication with three-dimensional printing (3DP) technique was used to fabricate a metallic mold with the same shape required to fill the gap in the opening wedge osteotomy. The mold was subsequently used in a CS process to fabricate the personalized ceramic implants with TCP and HA compositions. The mold geometry was designed on commercial 3D CAD software. The final personalized bioceramic implant was produced using a CS process. This technique was chosen because it exploits the exothermic reaction between P?O? and CaO. Also, chemical composition and distribution of pores in the implant could be controlled. To determine the chemical composition, the microstructure, and the mechanical properties of the implant, cylindrical shapes were also fabricated using different fabrication parameters. Chemical composition was performed by X-ray diffraction. Pore size and pore interconnectivity was measured and analyzed using an electronic microscope system. Mechanical properties were determined by a mechanical testing system. The porous TCP and HA obtained have an open porous structure with an average 400?μm channel size. The mechanical behavior shows great stiffness and higher load to failure for both ceramics. Finally, this personalized ceramic implant facilitated the regeneration of new bone in the gap created by OWHTO and provides additional strength to allow accelerated rehabilitation.     

Is hydroxyapatite cement an alternative for allograft bone chips in bone grafting procedures? A mechanical and histological study in a rabbit cancellous bone defect model

To evaluate in vivo performance of hydroxyapatite cement (HAC) as a porous bone graft substitute, HAC was mixed (1:1 ratio) with either porous calcium-phosphate granules (80% tricalcium phosphate, 20% hydroxyapatite) or defatted morsellized cancellous bone (MCB) allograft and implanted bilaterally in cylindrical drill holes in distal femurs of rabbits. Groups with empty defects and impacted MCB were used for reference. After 8 weeks, one femur from each pair was examined histologically. All contralateral specimens and Time-0 specimens were used for mechanical indentation tests. Histology showed that some empty defects were filled with newly formed osteopenic bone after 8 weeks. The impacted MCB showed remodeling into new vital bone. Incorporation of the HAC/MCB composite was incomplete, whereas minimal new bone ingrowth was found in the HAC/granule composites. Though not different from each other, both composites were significantly stronger than empty defects, incorporated impacted MCB, and intact cancellous bone. At Time 0, the mechanical behavior of impacted MCB was similar to both HAC composites. In conclusion, composites of HAC and porous biomaterials can maintain relatively high strength over 8 weeks in vivo, but their incorporation into a new bony structure is slower than impacted MCB. The HAC/MCB composite showed favorable incorporation behavior.     

壳聚糖与海藻酸钙双相陶瓷骨支架的机械性能及细胞相容性

BACKGROUND: Hydroxyapatite/β-tricalcium phosphate biphasic ceramic bone has good cell compatibility, but its mechanical properties are poor. OBJECTIVE: To construct chitosan/ or calcium alginate/biphasic ceramic bone scaffolds and to detect their mechanical properties and cytocompatibility. METHODS: Different concentrations of chitosan (2%, 4%, 7%, 10%) or calcium alginate (3%, 4%, 5%, 7%) were mixed with biphasic ceramic bone to prepare chitosan/biphasic ceramic bone scaffold and calcium alginate/biphasic ceramic bone scaffold. Their morphology and structure, coagulation time, anti-dissolution properties, shear force, compressive strength and cell compatibility were detected. RESULTS AND CONCLUSION: (1) Coagulation time: with the concentration increase, the initial and final setting time of these two kinds of composite scaffolds were prolonged to some extent. (2) Scanning electron microscopy: these two kinds of composite scaffolds showed porous microstructures with different pore sizes. (3) Anti-dissolution properties: the calcium alginate/biphasic ceramic bone scaffold (3%, 4%, 5%, 7%) and chitosan/biphasic ceramic bone scaffold (7%, 10%) had good anti-dissolution properties in the liquid. (4) Mechanical strength: with the concentration increase, the shear force and compressive strength of the calcium alginate/biphasic ceramic bone scaffold were reduced. (5) Cell compatibility: the cytotoxicity of chitosan/ or calcium alginate/biphasic ceramic bone scaffolds was graded as 0-1 or 2-3, respectively. These results show that the chitosan/biphasic ceramic bone scaffold has better mechanical properties and cell compatibility than the calcium alginate/biphasic ceramic bone scaffold.      

Wear properties of alumina/zirconia composite ceramics for joint prostheses measured with an end-face apparatus

While only alumina is applied to all-ceramic joint prostheses at present, a stronger ceramic is required to prevent fracture and chipping due to impingement and stress concentration. Zirconia could be a potential substitute for alumina because it has high strength and fracture toughness. However, the wear of zirconia/zirconia combination is too high for clinical use. Although some investigations on composite ceramics revealed that mixing of different ceramics was able to improve the mechanical properties of ceramics, there are few reports about wear properties of composite ceramics for joint prosthesis. Since acetabular cup and femoral head of artificial hip joint are finished precisely, they indicate high geometric conformity. Therefore, wear test under flat contact was carried out with an end-face wear testing apparatus for four kinds of ceramics: alumina monolith, zirconia monolith, alumina-based composite ceramic, and zirconia based composite ceramic. Mean contact pressure was 10 MPa and sliding velocity was 40 mm/s. The wear test continued for 72 hours and total sliding distance was 10 km. After the test, the wear factor was calculated. Worn surfaces were observed with a scanning electron micrograph (SEM). The results of this wear test show that the wear factors of the both composite ceramics are similarly low and their mechanical properties are much better than those of the alumina monolith and the zirconia monolith. According to these results, it is predicted that joint prostheses of the composite ceramics are safer against break down and have longer lifetime compared with alumina/alumina joint prostheses.     

Tibial tray thickness does not significantly increase medial tibial bone resorption: Using tibial bone density as an objective measurement method

BackgroundRecent studies have reported the occurrence of medial tibial bone resorption following total knee replacement. One study proposed that a thick tibial tray results in stress shielding and increases the risk of bone resorption, but its findings were based on subjective radiological assessment. This study aimed to verify this hypothesis and to objectively quantify medial tibial bone density by using serial measurements with digital radiological densitometry.MethodsThis was a retrospective cohort study involving 140 patients (70 thick tray vs. 70 thin tray) with cobalt–chromium implants with at least 24 months of follow-up. Standard radiographs were reviewed to look for incidence of medial tibial bone loss. Serial measurement of medial tibial bone density was also performed using the method of digital radiological densitometry.ResultsThere was no significant difference in the incidence of medial tibial bone loss. Both groups showed a significant drop in medial tibial bone density after operation (P < 0.01). Medial tibial bone density of the thick-tray cohort was significantly higher than the thin-tray cohort at one year (93.3 vs. 83.1 Greyscale; P = 0.04), but not at two and three years. Clinical outcomes in terms of postoperative range of motion, Knee Society score and complication rates were similar.ConclusionsMedial tibial bone resorption is a common phenomenon. Implants with thicker tibial trays suffer less than those with thinner trays at one year, but the difference is transient and does not affect clinical outcome.     

In vivo evaluation of a porous hydroxyapatite/poly-DL-lactide composite for bone tissue engineering

As reported previously, a porous composite of uncalcined hydroxyapatite (u-HA) and poly-DL-lactide (PDLLA) showed excellent osteoconductivity and biodegradability as a bone substitute in rabbit model. In this study, to investigate the usefulness of this composite as a scaffold loaded with cells, we estimated whether this material showed osteogenesis on implantation to extraosseous site. On loading with syngeneic bone marrow cells and implantation into rat dorsal subcutaneous tissue, osteogenesis with enchondral ossification was seen both on and in the material at 3 weeks after implantation. The osteogenesis in the u-HA/PDLLA had progressed, and newly formed bone tissue was found in the material by 6 weeks. To investigate the osteoinductive properties of the material, we implanted this porous composite material into extraosseous canine dorsal muscle. At 8 weeks, osteogenesis was seen in the pores of the material. Newly formed bone could be observed adjacent to the material. In addition, cuboidal osteoblasts adjacent to the newly formed bone were evident. Neither cartilage nor chondrocytes were found. These results might indicate that the material induced osteogenesis by intramembranous ossification. Conversely, similar porous PDLLA did not induce osteogenesis during the observation period. Therefore, porous HA/PDLLA, which has osteoconductive and osteoinductive properties, might be a useful material for use as a bone substitute and cellular scaffold.     

High protracted 99mTc-HDP uptake in synthetic bone implants — A potentially misleading incidental finding on bone scintigraphy

We report the case of a 56-year-old male with bilateral total knee prostheses suffering from bilateral knee pain mainly on the right side and referred for bone scintigraphy. The medical history of the patient revealed an opening wedge high tibial osteotomy performed nine years earlier, with insertion of two blocks of ceramic made of hydroxyapatite and tricalcium phosphate in a wedge configuration as synthetic bone substitutes. The porous structure of these implants is analogous to the architecture of cancellous bone and permits fibrovascular and bone ingrowth, promoting the healing process. Planar scintigraphy and SPECT/CT showed an intense uptake within those implants in the early phase as well as in the late phase of the bone scan. It also showed bilateral patellofemoral arthritis. A ^99mTc-labeled antigranulocyte antibody scintigraphy was negative for infection or inflammation. Bilateral patellar resurfacing led to complete symptom regression, confirmed at 10 months follow-up. To the best of our knowledge, this scintigraphic pattern with such a high tracer uptake reflecting bone substitute osteointegration has not yet been published. This should be considered in patients with such bone replacement materials that are increasingly used, in order to avoid false diagnosis of inflammation or infection.