假体四种表面处理的体内植入实验

目的探讨骨形态发生蛋白(BMP)与植入体的复合方法及植入体复合BMP后对骨-植入体界面的骨长入与结合强度的作用,为人工关节生物固定方法的改进提供实验依据。方法取12只成年杂种犬,随机分成三个时间组,取双侧股骨为种植区。将多孔金属表面(PCA)植入体、BMP2复合PCA植入体、喷涂羟基磷灰石(HA)的PCA植入体及喷涂HA的光滑金属表面植入体植入犬皮质骨后,分别于术后4、8及12周取出,通过X线摄片、不脱钙骨磨片、荧光显微镜、软X线摄片、骨计量学等方法对骨-植入体界面进行组织学和形态学的综合观察分析。结果各种植入体均具有良好的组织相容性。植入体表面复合BMP后,骨长入植入体界面的时间早于其它方法,新生骨组织成熟也较早。各时间段BMP复合PCA植入体组的新生骨形成率均较其它组高,但仅在4周时差异有显著性(P<0.05)。结论实验中采用的BMP与植入体的复合方法简单有效,BMP的应用可使骨与假体界面之间较早达到牢固固定。HA涂层方法能够促进骨组织长入及增强骨-植入体界面结合强度,并在中晚期有一定的优势,但是其喷涂工艺对固定效果有较大的影响,在假体的制造过程中应予以重视。     

生物活性梯度HA涂层人工关节的生物力学研究

[目的]探讨生物活性梯度羟基磷灰石(HA)涂层人工关节的生物力学性能。[方法]在人工股骨头置换组,将10只健康成年杂交犬随机分成2组,行右侧人工股骨头置换,分别植入钛合金人工股骨柄(Ti关节组)、HA涂层钛合金人工股骨柄(HA关节组);在圆柱体植入组,选4只健康成年杂交犬,麻醉后在股骨内外髁关节面垂直植入1个种植体,左腿植入钛合金棒(Ti圆柱体组),右腿植入羟基磷灰石涂层钛合金棒(HA圆柱体组),术后12周处死动物取材,进行生物力学测试和界面组织学观察。[结果]生物力学顶出试验显示:Ti关节组、HA涂层关节组的抗剪切强度分别为(2.58±1.56)Mpa和(7.57±1.03)Mpa,HA涂层关节组的抗剪切强度明显高于Ti关节组(P<0.01)。Ti圆柱体组、HA涂层圆柱体组的抗剪切强度分别为(2.36±1.04)Mpa和(21.65±1.48)Mpa。HA涂层圆柱体组的抗剪切强度明显高于Ti圆柱体组(P<0.01)。界面组织学观察显示:HA关节组和HA圆柱体组界面骨结合良好,骨结合率高;而Ti关节组和Ti圆柱体组界面大部分区域钛金属表面与周围的骨小梁之间有纤维组织分隔,界面骨结合率低。[结论]生物活性梯度HA涂层人工关节有良好的生物力学性能,界面较高的骨结合率是HA涂层植入体获得良好的生物力学性能的基础。     

重组人骨形态发生蛋白-2用于人工关节生物固定方法的研究

目的 探讨复合重组人骨形态发生蛋白-2(rhBMP2)植入体对骨-假体界面骨长入及结合强度的作用。方法将多孔金属表面植入体(PCA)与复合．rhBMP2的PCA植入体、HA涂层植入体及：PCA表面喷涂HA植入体植入犬皮质骨并综合运用X线摄片、软X线照相、不脱钙骨组织磨片、荧光显微镜检查、骨组织计量学分析及生物力学测定等方法对骨-植入体界面的骨长入及界面的结合强度进行了比较分析。结果术后软X线照相、组织学、骨组织计量学及生物力学比较分析显示复合rhBMP2的植入体在各时间组的新生骨形成率和界面剪切强度均优于其它各组;以4周时最为明显,且差异有非常显著意义。结论植入体复合rhBMP2后在促进早期骨-假体界面的骨长入和结合强度方面优于其它各种方法,有利于早期骨与假体间的结合和固定。     

犬骨形态发生蛋白/羟基磷灰石梯度涂层骨的结合性能

目的探讨复合重组人骨形态发生蛋白(rhBMP)的羟基磷灰石(HA)梯度涂层植入体的界面骨结合性能。方法6只健康成年杂交犬股骨内、外髁关节面各垂直植入1个种植体,共植入钛合金圆柱体(Ti组)、HA涂层钛合金圆柱体(HA组)、复合rhBMP的HA涂层钛合金圆柱体(BMP组)各8个。12周时取材进行界面组织学观察、顶出试验和扫描电镜检查。结果界面组织学和扫描电镜观察显示HA组和BMP组界面骨结合良好。Ti组、HA组和BMP组骨结合率分别为(11.53±10.79)%、(81.51±4.53)%、(92.71±5.30)%(P<0.01);抗剪切力强度分别为(2.36±1.04)、(21.65±1.48)、(30.95±3.67)Mpa(P<0.01)。结论复合BMP的HA梯度涂层在负重情况下界面骨结合好,结合强度高,已具备应用于新型涂层假体研制的生物学性能。     

纳米级羟基磷灰石梯度涂层植入体骨结合的研究

目的评价纳米级羟基磷灰石梯度涂层(HAP)植入体-骨界面骨结合情况。方法在Beagle犬股骨内植入纳米级HAP梯度涂层栓、普通级HAP涂层栓和钛合金(Ti-6AL-4V)栓,在4、8、12周比较X线结果和植入体-骨界面剪切强度。结果各时间点纳米级HAP涂层组和普通HAP梯度涂层组的X线结果相当,植入体-骨界面剪切强度均优于钛合金组和钛合金组。结论纳米级HAP梯度涂层植入体与骨有很好的结合力,能够加速骨质的愈合。     

人工关节非骨水泥固定方法的生物力学分析

目的　为人工关节生物固定方法的改进提供一些理论及实验依据。方法　通过推出试验 (Push out)方法对BMP2复合多孔金属表面植入体、多孔金属表面植入体、喷涂HA的PCA植入体、羟基磷灰石涂层植入体在填入骨 -假体交界面后界面的结合强度进行检测 ,并对获得的数据进行统计学分析。结果　BMP对界面结合强度有增强作用 ,在植入的早期尤其显著。结论　对植入体表面进行多孔处理并复合HA对中期促进骨与植入体结合效果显著 ,在假体制造工艺中HA涂层的制备对假体的生物固定效果有较大的影响     

人工关节非骨水泥固定方法的生物力学分析

目的 为人工关节生物固定方法的改进提供一些理论及实验依据。方法 通过推出试验(Push-out)方法对BMP2复合多孔金属表面植入体、多孔金属表面植入体、喷涂HA的PCA植入体、羟基磷灰石涂层植入体在填入骨-假体交界面后界面的结合强度进行检测，并对获得的数据进行统计学分析。结果 BMP对界面结合强度有增强作用，在植入的早期尤其显著。结论 对植入体表面进行多孔处理并复合HA对中期促进骨与植入体结合效果显著，在假体制造工艺中HA涂层的制备对假体的生物固定效果有较大的影响。     

等离子喷涂硅灰石涂层种植体体内植入的实验研究

目的对硅灰石（CaSiO3）涂层的生物学性能进行评价,为临床选择种植体表面改性方法提供实验依据。方法在纯钛棒表面采用等离子喷涂的方法分别加涂CaSiO3涂层和羟基磷灰石（HA）涂层,切割成直径3mm、高12mm的圆柱状植入体各12枚,植入实验狗的下颌骨内,检测种植体-骨界面的结合强度,并用扫描电镜进行形态观测。结果植入3个月后,CaSiO3涂层种植体-骨界面的剪切结合强度高于HA涂层种植体-骨界面的剪切结合强度,二者之间有显著差异（P〈0．05）。结论CaSiO3涂层具有良好的生物活性,是一种较有应用前途的种植体涂层材料。     

等离子喷涂羟基磷灰石涂层人工股骨柄的研制

目的 :研制新型羟基磷灰石涂层人工关节。方法 :采用等离子喷涂及外送粉装置对人工股骨柄进行全柄喷涂。运用X线衍射仪、X线表面能谱仪、红外线光谱仪、扫描电镜及力学实验对涂层进行分析。结果 :涂层成分主要为羟基磷灰石 ,基本上未发生热分解 ,涂层与金属基体之间的平均结合强度为 2 9 71MPa。结论 :国产等离子喷涂羟基磷灰石涂层基本保持了羟基磷灰石材料的特性 ,结合强度能够满足关节假体的需要。     

等梯度羟基磷灰石涂层植入体的实验研究

目的：观察一种新的等梯度羟基磷灰石（ＨＡ）涂层结构的骨－ＨＡ界面的生物力学及生理学特征。方法：应用经皮质骨植入体模式，在１２条狗的双侧股骨上共植入９６个ＨＡ表面涂层及非涂层钛合金栓。分别于术后６、１２及１８周处死后取材。测定界面抗剪强度并作组织学观察。结果：在要诟任一时间段涂层植入体界面抗剪强度均显著高于非涂层者。涂层植入人体表面成骨活跃，骨与涂层结合紧密，而非涂层植入体表面与骨组织间有纤维组织存     

羟基磷灰石梯度涂层的生物学研究

目的：本实验研究HA梯度涂层材料在体内负重条件下的生物学表现,方法：将经梯度涂层羟基磷灰石的钛合金栓与非涂层钛合金栓分别植入狗下肢的负重区,观察植入体与骨结合界面的生物学特性,结果：组织学研究显示类骨样基质直接沉积在HA涂层表面,涂层与宿主骨紧密结合。而非涂层组新生骨形成的数量和速度远低于HA涂层组,生物力学测试显示HA组与宿主骨结合界面的抗剪强度均远大于非涂层组（P＜0．01）,结论：结果表明HA梯度涂层法作为新颖的层方法有其实际临床应用价值。     

Interfacial shear strength of bioactive‐coated carbon fiber reinforced polyetheretherketone after in vivo implantation

Despite the excellent osseointegration of carbon‐fiber‐reinforced polyetheretherketone (CFR/PEEK) with a surface hydroxyapatite (HA) coating, the bone‐implant interfacial shear strength of HA‐coated CFR/PEEK after osseointegration is unclear. We examined the interfacial shear strength of HA‐coated CFR/PEEK implants after in vivo implantation in a rabbit femur‐implant pull‐out test model. HA coating was performed by a newly developed method. Uncoated CFR/PEEK, HA‐coated blasted titanium alloy, and uncoated blasted titanium alloy were used as control implants. The implants were inserted into drilled femoral cortex, and pull‐out tests were conducted after 6 and 12 weeks of implantation to determine maximum interfacial shear strength. The HA‐coated CFR/PEEK (15.7 ± 4.5 MPa) and HA‐coated titanium alloy (14.1 ± 6.0 MPa) exhibited significantly larger interfacial shear strengths than the uncoated CFR/PEEK (7.7 ± 1.8 MPa) and the uncoated titanium alloy (7.8 ± 2.1 MPa) at 6 weeks. At 12 weeks, only the uncoated CFR/PEEK (8.3 ± 3.0 MPa) exhibited a significantly smaller interfacial shear strength, as compared to the HA‐coated CFR/PEEK (17.4 ± 3.6 MPa), HA‐coated titanium alloy (14.2 ± 4.8 MPa), and uncoated titanium alloy (15.0 ± 2.6 MPa). Surface analysis of the removed implants revealed detachment of the HA layer in both the HA‐coated CFR/PEEK and titanium alloy implants. The proposed novel HA coating method of CFR/PEEK significantly increased interfacial shear strength between bone and CFR/PEEK. The achieved interfacial shear strength of the HA‐coated CFR/PEEK implant is of the same level as that of grit‐blasted titanium alloy with HA. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1618–1625, 2012     

Bone ingrowths to press-fit and loose-fit implants: comparisons between titanium and hydroxyapatite

The aim of this study was to investigate whether the coating of titanium (Ti) implants with hydroxyapatite (HA) might create a better fixation when titanium implants are implanted into a gap. In each of 16 rats, the medullary cavity of both femurs was entered by an awl from the trochanteric area. With steel burrs it was successively reamed to a diameter of 1.5 mm. In a random manner the proximal part of the cavity in half of the bones was reamed once again to a diameter of 2.0 mm. Nails with a diameter of 1.5 mm and a length of 34 mm were then inserted into the medullary cavity of these bones with press fit at the distal half and a gap to the bone in the proximal half. In the remaining bones the whole medullary canal was reamed to a diameter of 2.0 mm, and nails with a diameter of 2.0 mm and a length of 34 mm were introduced. In all cases, either a pure Ti nail or a Ti nail entirely plasma sprayed with HA was used in a random manner. The surface roughness of the pure Ti was characterized by Ra 2.6 microm and Rt 22 microm. Ra of HA was 7.5 microm and Rt 52 microm. At sacrifice after 16 weeks, both femurs were dissected free from soft tissues and then immersed in fixative. A specimen slice of about 5 mm in thickness was prepared from the subtrochanteric region with a water-cooled band saw. Sample preparation for undecalcified tissue followed the internal guidelines at the laboratories of the Department of Biomaterials/Handicap Research. Generally, bone contact to the nails with HA coating was more predictable than was bone contact to the Ti nails. But due to rather large variations in bone contact between the samples, statistical analyses revealed non-significant differences between the 4 groups (p = 0.083). There were no significant differences between Ti and HA coated nails of 2.0 mm (p = 0.633), nor between Ti and HA coated nails of 1.5 mm (p = 0.924). The pooled values for the 2.0 mm nails showed significantly higher bone bonding contact than the pooled values of the 1.5 mm nails (p = 0.011). Our results, then, indicate that bone bonding contact to implants with a loose fit insertion is less predictable than in press fit insertion, and HA coating seemed to be more predictable than pure Ti. However, due to large variations between the samples, the differences did not reach significant levels.     

Enhancement of the fixation of pyrolytic carbon implants by using atomic oxygen texturing

The purpose of this study was to examine the effect on the biocompatibility and biologic fixation of atomic oxygen-textured pyrolytic carbon. The implants consisted of unalloyed pyrolytic carbon rods, with half the length of the rod textured by atomic oxygen, and the other half retaining the as-deposited surface that normally occurs during the manufacturing process. The rods were implanted transcortically across the distal portion of the femurs of 6 adult male rabbits for 8 weeks. The implants were assessed mechanically by measuring the interface strength between the implant and the bone. The implant-bone interface was also examined by light microscopy. No adverse reaction to either the as-deposited or the textured pyrolytic carbon was seen. Percent bone apposition was greater for textured implants than for the as-deposited implants; however, it was not significant. The bone apposition efficiency factor, calculated by dividing the interface strength by the fraction of bone apposition, was greater for the textured implants than for the as-deposited implants. This indicates that the fixation obtained was more effective for the textured implants. The findings of this study suggest that biologic fixation of pyrolytic carbon implants can be enhanced by surface texturing by using direct exposure to atomic oxygen, without compromising its biocompatibility.     

Hydroxyapatite-coated titanium for orthopedic implant applications

The interface mechanical characteristics and histology of commercially pure (CP) titanium- and hydroxyapatite- (HA) coated Ti-6Al-4V alloy were investigated. Interface shear strength was determined using a transcortical push-out model in dogs after periods of three, five, six, ten, and 32 weeks. Undecalcified histologic techniques with implants in situ were used to interpret differences in mechanical response. The HA-coated titanium alloy implants developed five to seven times the mean interface strength of the uncoated, beadblasted CP titanium implants. The mean values for interface shear strength increased up to 7.27 megaPascals (MPa) for the HA-coated implants after ten weeks of implantation, and the maximum mean value of interface shear strength for the uncoated CP titanium implants was 1.54 MPa. For both implant types there was a slight decrease in mean shear strength from the maximum value to that obtained after the longest implantation period (32 weeks). Histologic evaluations in all cases revealed mineralization of interface bone directly onto the HA-coated implant surface, with no fibrous tissue layer interposed between the bone and HA visible at the light microscopic level. The uncoated titanium implants had projections of bone to the implant surface with apparent direct bone-implant apposition observed in some locations. Measurements of the HA coating material made from histologic sections showed no evidence of significant HA resorption in vivo after periods of up to 32 weeks.     

Comparison of hydroxyapatite and hydroxyapatite tricalcium-phosphate coatings

This study compared the effects of hydroxyapatite (HA) coating and biphasic HA/tricalcium-phosphate (HA/TCP) coating on the osseointegration of grit-blasted titanium-alloy implants. Each coated implant was compared with uncoated grit-blasted implants as well. The implants were press-fit into the medullary canal of rabbit femora, and their osseointegration was evaluated 3 to 24 weeks after surgery. The coated implants had significantly (P<.05) greater new bone ongrowth than the uncoated implants (HA, 56.1 +/- 3.1%; HA/TCP, 53.8 +/- 2.6%; uncoated, 32.2 +/- 1.4% of the implant perimeter, 12 weeks). Unmineralized tissue (cartilage and osteoid) was seen on the uncoated implants but never on the coated implants. The coated implants had significantly (P<.05) greater interfacial shear strength than the uncoated implants (HA, 4.1 +/- 0.4 MPa; HA/TCP, 4.8 +/- 0.5 MPa; uncoated, 2.6 +/- 0.2 MPa, 12 weeks). There was no difference between HA and HA/TCP coating in regard to new bone growth or interfacial shear strength. These data show a comparable enhancement effect of HA and HA/TCP coatings on the osseointegration of titanium-alloy implants.     

Influence of biomaterial surface texture on bone ingrowth in the rabbit femur

The purpose of this study was to examine both the histologic and the mechanical characteristics of bone apposition to an experimental surface, arc-deposited titanium, in a rabbit model and to compare them with those of four previously studied surfaces: one layer of cobalt-chromium beads, three layers of cobalt-chromium beads, plasma-sprayed cobalt-chromium, and uncoated titanium alloy. Bilateral cylindrical implants were press-fit into the lateral femoral condyles of 70 adult New Zealand White rabbits, which were allowed unrestricted activity and then killed at 6 or 12 weeks. The distal femora were harvested, radiographed, and prepared for either mechanical or histologic evaluation. All of the implants with coated surfaces had significantly greater shear strength than the implants of grit-blasted titanium alloy after both 6 and 12 weeks. After 6 weeks, maximum bone apposition occurred in the beaded surfaces. After 12 weeks, the shear strengths and bone apposition of implants of arc-deposited titanium and of one and three layers of cobalt-chromium beads were significantly greater than those of implants of plasma-sprayed cobalt-chromium and grit-blasted titanium alloy. The histologic studies correlated with the mechanical results. After 12 weeks, the bone apposition and mechanical stability of arc-deposited titanium were similar to those of a single layer of beads. There appeared to be no advantage to multiple layers of beads, and the plasma-sprayed cobalt-chromium and gritblasted titanium surfaces showed lower shear strength and bone apposition than the other groups.     

Hydroxyapatite coating modifies implant membrane formation. Controlled micromotion studied in dogs.

We studied the influence of controlled micromovements between bone and porous titanium alloy implants with and without hydroxyapatite coating. A dynamically loaded unstable device producing approximately 150-microns axial translation of knee implants during each gait cycle was developed. Stable implants served as controls. Matched stable and unstable implants with either porous titanium (Ti) or hydroxyapatite (HA) coating surrounded by a gap of 0.75 mm were inserted into the weight-bearing regions of the medial femoral condyles in 14 mature dogs. Histologic analysis after 4 weeks showed a fibrous membrane surrounding both types of implants subjected to micromovements, whereas various amounts of bone ingrowth was obtained in the stable implants. The membrane around unstable HA implants was thinner than that around unstable Ti implants. Islands of fibrocartilaginous tissue characterized the membrane around unstable HA implants, whereas fibrous connective tissue surrounded unstable Ti implants. The collagen concentration of the fibrous membranes was higher around unstable HA implants compared with Ti implants. Instability reduced the shear strength of the implants. However, the shear strength of unstable HA implants exceeded that of the Ti implants, both unstable and stable. The greatest shear strength was obtained by stable HA implants, i.e., tenfold greater than that of stable Ti implants. The gap-healing capacity around stable HA implants increased toward the HA surface, and was greater than that around Ti implants. Our study demonstrates that micromovements between bone and implant inhibit bone ingrowth and lead to the development of a fibrous membrane. The superior fixation of unstable HA implants compared with unstable Ti implants may be ascribed to the presence of fibrocartilage, a higher collagen concentration, and radiating orientation of collagen fibers in the membrane. The strongest mechanical anchorage and the greatest amount of bone ingrowth was obtained by stable implants coated with hydroxyapatite.     

Functional osseointegration of hydroxyapatite-coated implants in a weight-bearing canine model

That hydroxyapatite (HA) can form a strong chemical bond with bone has been confirmed by several precedent workers using unloaded implants. The relation-ship between the histomorphometric measurements of the interface of the cementless femoral stems with and without HA coating and their mechanical properties in a weight-bearing canine model was evaluated in this study. Seven HA-coated and seven uncoated titanium (Ti6Al4V) hemiarthroplasties were implanted in the right hip of 14 dogs for a 5-month period. The specimens were taken to conduct mechanical testing andmorphometric measuring. The average interface shear strength of 2.13 MPa for the HA-coated specimens was significantly higher than 0.93 MPa for the uncoated specimens (P<.05). There was greater bone apposition with the HA coating (72.39%) than without the coating (15.96%). Bone interfaces were divided into tow types histomorphometrically: type A, simple bony shell without supporting trabeculae and type B, buttressed bony shell with supporting trabeculae. A positive correlation between the type B HA-bone interface and interface shear strength was found (r=.81)