Stress transfer at the femoral bone/bone cement interface as a function of the cement thickness

Summary When a cement canal prosthesis is used as the femoral component in total hip replacement (THR), the penetration depth of the bone cement can be varied according to the cement implantation pressure. Using experimental data which give a relation between the pressure applied to the cement at implantation and the resulting shape of the cement layer, a three-dimensional finite element study was performed to calculate the stress distribution at the bone/bone cement interface. The calculations show that the interface stresses increase with increasing depth of penetration by the cement layer. The explanation of this effect is that as the bone cement penetrates further into the cancellous bone, the cancellous bone is stiffened and can no longer act as a soft interposition between cortical bone and bone cement. From these results and from the clinical requirement that as little bone as possible be destroyed in any kind of alloarthroplasty, we conclude that the penetration depth of bone cement into cancellous bone in THR should be minimized to the depth necessary in order to achieve sufficient initial stability of the implant. The results show that a cement-canal prosthesis meets these requirements if a cement implantation pressure of 1.0 bar is used.     

Effect of cement pressure and bone strength on polymethylmethacrylate fixation

The effect of the quality of the bone and of the cement pressurization magnitude and duration on the fixation achieved with polymethylmethacrylate (PMMA) bone cement is studied in vitro. Seventy-one cementbone interface specimens, prepared under various conditions of pressurization of low-viscosity bone cement, are tested in tension. The load at failure and the maximum cement penetration are measured to assess the fixation achieved, and the quality of the bone is assessed by determining the compressive strength of each of the bone specimens. Statistical analysis of the data indicates that the pressure magnitude is the most influential of the factors considered in the cement penetration behavior and in the development of failure load capacity. The duration of the pressure does not appear to be a significant factor. The cement penetration is a decreasing function of the bone strength, reflecting a decrease in the porosity and an increase in the area fraction. Although not directly measured in these tests, these latter bone properties are indirectly measured by the bone compressive strength. The effect of increasing bone strength on the failure load is nonlinear. The development of adequate failure load capacity is the result of a balance between the cement penetration allowed by the porosity of the bone and the inherent strength of the cancellous bone itself. Weak bone, although adequately penetrated by cement, cannot provide strong fixation. Stronger, denser bone limits cement penetration, but pressurization enhances development of failure load capacity through more complete infusion and interlocking of the cement in the available pore space. The strength of the fixation achievable for any bone is limited by the intrinsic strength of the bone. An optimal depth of cement penetration of 4 mm and an optimal bone area fraction of 0.20 are suggested for the most effective fixation.     

Treatment of benign bone tumours of the hand using osteoscopy

Curettage and bone grafting are used traditionally to treat benign bone tumours of the hand. Some authors are proposing minimally invasive treatment using endoscopy. Our purpose is to standardise this technique based on a study of the number and locations of entry points. This is a report on three benign metacarpal bone tumours treated with three different endoscopic approaches: multiportal, extended uniportal and oblique uniportal. In theory, the multiportal approach has several drawbacks: weakening of the bone cortex, a limited visual field and seepage of injectable phosphocalcic cement. The extended uniportal approach causes cortical defects, unacceptable in a minimally invasive technique. The oblique uniportal approach seems less troublesome; vision of the bone cavity is good, curettage of the tumour is complete, the bone cortex is undamaged and there is no leakage of injectable phosphocalcic cement. All things considered, the oblique osteoscopic uniportal approach seems to be the best option for the management of benign bone tumours of the hand.     

Effect of cement pressure and bone strength on polymethylmethacrylate fixation

The effect of the quality of the bone and of the cement pressurization magnitude and duration on the fixation achieved with polymethylmethacrylate (PMMA) bone cement is studied in vitro. Seventy-one cement-bone interface specimens, prepared under various conditions of pressurization of low-viscosity bone cement, are tested in tension. The load at failure and the maximum cement penetration are measured to assess the fixation achieved, and the quality of the bone is assessed by determining the compressive strength of each of the bone specimens. Statistical analysis of the data indicates that the pressure magnitude is the most influential of the factors considered in the cement penetration behavior and in the development of failure load capacity. The duration of the pressure does not appear to be a significant factor. The cement penetration is a decreasing function of the bone strength, reflecting a decrease in the porosity and an increase in the area fraction. Although not directly measured in these tests, these latter bone properties are indirectly measured by the bone compressive strength. The effect of increasing bone strength on the failure load is nonlinear. The development of adequate failure load capacity is the result of a balance between the cement penetration allowed by the porosity of the bone and the inherent strength of the cancellous bone itself. Weak bone, although adequately penetrated by cement, cannot provide strong fixation. Stronger, denser bone limits cement penetration, but pressurization enhances development of failure load capacity through more complete infusion and interlocking of the cement in the available pore space. The strength of the fixation achievable for any bone is limited by the intrinsic strength of the bone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reconstruction of post-traumatic frontal-bone depression using hydroxyapatite cement

The safety and efficacy of hydroxyapatite cement (Bone Source, Howmedica, Leibinger, Inc. Dallas, TX) use for the augmentation of post-traumatic frontal-bone depression was evaluated in a study of 20 consecutive oriental patients between June 1998 and July 2000 inclusively. The size of the depressed frontal bone ranged from 5 x 5 cm to 8 x 5 cm. The cement was placed in contact with the frontal sinus for 12 patients, none of whom revealed a history of paranasal sinus mucoperiosteal disease. Follow-up averaged 28 months for all 20 patients. Postimplantation evaluations included serial photographs, repeated physical examination, and 3-dimensional computed tomography for all patients. The cement paste allowed for precise and easy contouring of the bony depression's restoration. Meticulous hemostasis is essential to ensure a dry surgical field and successful application of the cement. No infection of the surgical site or extrusion of the cement was noted for any of our patients, and the contour of the reconstructed frontal bone was acceptable esthetically without any secondary depression noted during the follow-up period. Three-dimensional computed tomographic scans taken 2 years subsequent to implantation revealed good preservation of the cement restoration material. Small areas of cement loss due to cement absorption into the ambient fluid were noted for 2 patients, but such resorption did not appear to esthetically influence the final results. The results from this clinical study indicated that hydroxyapatite cement is a biocompatible, alloplastic material useful for augmentation of post-traumatic frontal-bone depression with stable volume maintenance over time. Judicious use of the hydroxyapatite cement offers an alternative to autogenous bone grafts or the use of methyl methacrylate for augmentation of the craniofacial skeleton among oriental patients.     

椎体成形术填充剂最优化分布模式三维有限元分析

目的:通过建立骨质疏松三维有限元模型,模拟液体流动进入椎体,研究不同状态骨水泥灌注量及分布条件下经皮椎体成形术术后伤椎刚度恢复及相邻椎体应力分析.方法:选取男性健康志愿者一名,从T11到L2之间使用CT扫描,采用Mimics 15.0以及ABAQUS6.11等软件提取CT图像,建立骨质疏松性骨折椎体模型,将模拟流动物理...     

磷酸钙骨水泥修复羊实验性胫骨平台压缩性骨折的组织学研究

目的 观察磷酸钙骨水泥在修复羊实验性外侧胫骨平台压缩性骨折中的吸收与成骨特点.方法 成年健康山羊10只,于双下肢外侧胫骨平台制作压缩性骨折伴骨缺损模型.一侧下肢缺损用磷酸钙骨水泥填充,对侧用自体骨填充.术后3个月和6个月分别处死5只动物,取双侧胫骨近端组织块,进行电镜观察;制备不脱钙切片进行组织学观察骨水泥吸收、自体骨吸收及新骨形成情况;测量骨形态计量学参数.结果 骨水泥表面可见大量重建陷窝锥形切割指向并穿入骨水泥,表面被无数破骨细胞和成骨细胞覆盖,骨水泥与表面的新生红色骨小梁结合紧密,无任何软组织层介入.骨形态计量学静态参数显示,骨水泥面积在3个月时为43.8%,6个月时仅剩29.9%;成骨细胞指数和破骨细胞指数在3个月时最大,至6个月时减小.动态参数显示,骨水泥组双标记线间的平均距离和矿化沉积速率与自体骨组接近,差异无统计学意义.结论 磷酸钙骨水泥在羊体内具有良好的降解成骨性能,骨水泥降解吸收高峰在3个月,植入6个月内骨水泥的吸收速度与骨形成速度基本持平,可作为合适的自体骨替代材料填充骨缺损.     

预混合磷酸钙骨水泥研究进展

磷酸钙骨水泥以其良好的生物相容性、骨传导性及可塑性被作为骨缺损重要的修复材料,其性能的改进研究仍然是生物医学骨组织工程领域的热点课题。预混合磷酸钙骨水泥较传统原位即时混合型磷酸钙骨水泥具有方便临床手术操作、节约手术时间、便于保存等优点,克服了即时混合不均匀、不充分的缺点,并能根据缺损部位形状不同而随意塑形,因而预混合磷酸钙骨水泥也成为该领域研究热点之一。     

经皮椎体成形术治疗老年骨质疏松性胸腰椎压缩性骨折术中骨水泥渗漏的相关因素

目的分析经皮椎体成形术(PVP)治疗老年骨质疏松性椎体压缩性骨折(OVCF)术中骨水泥渗漏的相关危险因素。方法收集2015年1月—2017年12月采用PVP治疗的297例老年OVCF患者资料。采用logistic回归法分析年龄、性别、骨折部位、椎体压缩程度、椎体终板/后壁完整性、骨折节段数、骨水泥注射量与骨水泥渗漏(椎间盘、软组织、血管内、椎管内及混合渗漏)的关系。结果术中共166例发生骨水泥渗漏,渗漏率55.9%。二元logistic回归分析示骨水泥剂量高是骨水泥渗漏的唯一危险因素。多元logistic回归分析示椎体压缩程度高和骨折节段数多是椎间盘渗漏的危险因素;骨水泥注射量大和椎体压缩程度高是软组织渗漏的危险因素;女性和年龄较低是血管内渗漏的危险因素;骨水泥注射量大和椎体终板/后壁破裂是椎管内渗漏的危险因素。结论不同的危险因素导致PVP术中不同的渗漏类型。明确不同危险因素与各渗漏类型间的相互关系有利于防止骨水泥渗漏的发生。     

复合骨水泥椎体间固定的生物力学研究及临床应用

按一定比例将脱钙骨粒(DBP)掺入骨水泥,行成年犬椎体间固定。分别于术后2、4、8、12周时处死。固定段行X线照片、CT扫描及生物力学测试。观察不同时相点的生物力学效应。结果显示:术后2、4周时复合骨水泥的抗压强度低于单纯骨水泥(P〈0.05),8周时两者相近(P〉0.05),12周时高于单纯骨水泥与正常脊柱功能运动单位(FSU)(P〈0.05)。而术后2、4周时,复合骨水泥的抗扭转强度优于单纯骨水泥,2、4、8周时,低于正常FSU,12周时与正常相近。临床应用于胸腰椎骨折侧前方减压后行椎体间固定。术后3个月、6个月CT复查,证明骨已长入骨水泥内。     

骨水泥填充修复骨缺损在翻修髋臼假体内侧移位松动中的疗效

目的探讨骨水泥填充修复骨缺损结合骨水泥髋臼假体在翻修髋臼假体内侧移位松动中的临床疗效。方法 2006年4月~2011年3月收治16例髋臼假体内侧移位松动患者,均采用骨水泥填充修复骨缺损结合骨水泥聚乙烯髋臼假体翻修松动的髋臼假体,对伴有股骨假体松动的患者,根据患者的骨质情况和骨缺损情况选择骨水泥翻修长柄假体(9例)、非骨水泥型广泛涂层假体(2例)或打压植骨结合骨水泥固定股骨柄假体(1例)。术后进行临床评估及X线评估。结果 16例患者术后平均随访2.6(1.5~6.2)年,未出现臼杯松动病例,Harris评分从术前的35(18~63)分提高到末次随访时的89(60~99)分。结论应用骨水泥填充修复骨缺损结合骨水泥髋臼假体翻修内侧移位松动的髋臼假体是一种有效的手术方法。     

新型椎弓根钉骨水泥强化系统的生物力学与骨水泥剂量关系

目的建立骨质疏松模型,研究骨质疏松情况下新型经皮长U形空心椎弓根钉骨水泥强化系统(PMI-NPPS)的生物力学与骨水泥剂量之间的关系。方法取年龄在2.5~3.0岁绵羊腰椎,根据羊腰椎大小定做特定尺寸的羊PMI-NPPS。将40个椎体分成A、B组,B组脱钙4 h,分别进行骨密度测量,统计学分析确认骨质疏松模型建立。制备50个骨质疏松椎体随机分成5组,置入羊PMI-NPPS及骨水泥,按剂量分为0 ml组、0.5 ml组、1.0 ml组、1.5 ml组、2.0 ml组,进行生物力学测试,然后得出骨水泥剂量与Fmax(最大拔出力)的关系。结果 A组骨密度值为(0.875±0.003)g/cm~3、B组骨密度值为(0.631±0.003)g/cm~3,B组骨密度值低于A组,差异有统计学意义(P0.05)。脱钙后椎体骨密度较脱钙前降低27.9%。0 ml组、0.5 ml组、1.0 ml组、1.5 ml组、2.0 ml组的Fmax分别为(372.34±47.96)N、(613.85±30.37)N、(760.64±51.18)N、(896.59±47.97)N、(1 011.59±47.97)N。Pearson相关分析结果提示骨水泥剂量与Fmax呈直线相关,线性回归方程为y=312.5x+418.75(R~2=0.977),且1.5 ml为最理想的骨水泥剂量。结论当骨水泥剂量为0~2 ml时,随着骨水泥剂量的增加,羊PMI-NPPS的Fmax越高,且呈线性相关;当骨水泥剂量为1.5 ml时,羊PMI-NPPS的Fmax可达到正常骨密度时内固定的强度。     

In vitro analysis of the cement mantle of femoral hip implants: development and validation of a CT-scan based measurement tool.

We developed, validated and assessed inter- and intraobserver reliability of a CT-scan based measurement tool to evaluate morphological characteristics of the bone-cement-stem complex of hip implants in cadaver femurs. Two different models were investigated: the stem-cavity model using a double tapered polished femoral-stem that is removed after cement curing and the plastic-replica model using a stereolithographic stem replica that is left in place during CT-scanning. Software was developed to segment and analyze connective CT-images and identify the contours of bone, cement, and stem based on their respective gray values. Volume parameters (whole specimen, cement, stem, air contents of bone and cement), concentricity parameters (distances between centroids of stem and cement, cement and bone, stem and bone), contact surfaces (bone/air and cement/bone) and bone cement mantle thickness parameters were calculated. A three-dimensional protocol was developed to evaluate the minimal mantle thickness out of the CT-plane. The average accuracy for surfaces within CT-images was 7.47 mm2 (1.80%), for bone and cement mantle thickness it was 0.51 mm (9.39%), for distances between centroids it was 0.38 mm (18.5%) and contours: 0.27 mm (2.57%). The intra- and interobserver reliability of air content in bone and cement was sub-optimal (intraclass-correlation coefficient (ICC) as low as 0.54 with an average ICC of 0.85). All other variables were reliable (ICC>0.81, average ICC: 0.96). This in vitro technique can assess characteristics of cement mantles produced by different cementing techniques, stem types or centralizers.     

Practical applications of antibiotic-loaded bone cement for treatment of infected joint replacements

The use of antibiotic-loaded bone cement is an accepted treatment method for infected joint arthroplasties. It is helpful to separate the use of antibiotic-loaded bone cement as a method of prophylaxis as compared with the treatment of an established infection. A low dose of antibiotic-loaded bone cement (< or = 1 g of antibiotic per batch of cement) should be used for prophylaxis, and high-dose antibiotic-loaded bone cement (> 1 g antibiotic per batch of cement) is indicated for treatment. The only commercially available antibiotic-loaded bone cement products are low dose, with the use of tobramycin or gentamicin as an antibiotic selection. High-dose antibiotic-loaded bone cement requires hand mixing by the surgeon to facilitate the use of high dosages and choices of multiple antibiotics. Treatment of infected hip and knee arthroplasties with high-dose antibiotic-loaded bone cement is aided by the use of spacers of various shapes and sizes. These spacers, whether they are static or articulating (mobile), are meant to provide local delivery of antibiotics, stabilization of soft tissues, facilitation of an easier reimplantation, and improved clinical outcomes.     

经皮椎体成形术后骨水泥渗漏的回顾性分析及预防策略

目的 回顾性分析我院152例187节胸腰椎骨折椎体成形术后患者(PVP或PKP)骨水泥渗漏的发生率及预防措施.方法 2007年5月～2012年5月共152例骨质疏松性胸腰椎体压缩性骨折(187节椎体)患者施行经皮椎体成形术(PVP)75节或经皮椎体后凸成形术(PKP)112节,术后对责任椎常规复查CT,统计显示骨水泥渗漏共65节(34.76%),其中PVP术38节(50.66%),PKP术27节(24.11%),渗漏至椎管内15节(8.02%,PVP术9节,PKP术6节)、椎间隙内13节(6.95%,PVP术7节,PKP术6节)、穿刺针道内8节(4.28%,PVP术4节,PKP术4节)、椎间静脉渗漏5节(2.67%,均为PVP节)、椎体周缘(椎体前缘、椎体旁)23节(12.30%,PVP术12节,PKP术11节)、神经根管内1节(0.53%,为PVP术),观察术后疗效,总结造成骨水泥渗漏的原因及预防方法.结果 所有患者术后疼痛明显减轻,出现骨水泥渗漏并发症的患者中,1例渗漏至神经根管内患者出现神经压迫症状,减压术后症状缓解,其余患者术后均无明显神经压迫症状.结论 椎体成形术后渗漏发生率较高(34.76%),以椎体周缘渗漏(35.38%)最为常见,但因渗漏而有临床症状者较少(1.53%).骨水泥渗漏与术前检查是否充分、术前阅片是否仔细、手术操作是否熟练密切相关.     

Experimental micromechanics of the cement–bone interface

Despite the widespread use of cement as a means of fixation of implants to bone, surprisingly little is known about the micromechanical behavior in terms of the local interfacial motion. In this work, we utilized digital image correlation techniques to quantify the micromechanics of the cement–bone interface of laboratory‐prepared cemented total hip replacements subjected to nondestructive, quasistatic tensile and compressive loading. Upon loading, the majority of the displacement response localized at the contact interface region between cement and bone. The contact interface was more compliant (p = 0.0001) in tension (0.0067 ± 0.0039 mm/MPa) than compression (0.0051 ± 0.0031 mm/MPa), and substantial hysteresis occurred due to sliding contact between cement and bone. The tensile strength of the cement–bone interface was inversely proportional to the compliance of the interface and proportional to the cement/bone contact area. When loaded beyond the ultimate strength, the strain localization process continued at the contact interface between cement and bone with microcracking (damage) to both. More overall damage occurred to the cement than to the bone. The opening and closing at the contact interface from loading could serve as a conduit for submicron size particles. In addition, the cement mantle is not mechanically supported by surrounding bone as optimally as is commonly assumed. Both effects may influence the longevity of the reconstruction and could be considered in preclinical tests. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:872–879, 2008     

骨水泥振动器的运用对骨水泥-骨界面微嵌合的影响

目的 评价骨水泥振动器对提高骨水泥-骨界面的整合效果及临床意义. 方法 取新鲜成猪股骨16根,随机分成两组,实验组(A组)与对照组(B组)模型各8根.猪股骨髓腔内应用骨水泥振动器进行骨水泥灌注后(对照组灌注骨水泥不经振动),对每组实验模型进行硬组织切片,每根股骨模型等距选取3个层面,HE染色后在体视显微镜下观察,经电脑Motic Med 6.0数码医学图像分析系统分析测量骨水泥渗透入松质骨腔的厚度,记为渗透厚度,将所得数值进行统计学分析,对比振动组与对照组的骨水泥灌注效果. 结果 体视显微镜下显示实验组骨水泥与骨小梁之间结合紧密,骨水泥在松质骨腔内充填均匀一致,骨水泥与骨小梁之间的结合紧密.对照组骨水泥向松质骨腔内渗透欠佳,在松质骨腔内充填不均匀.结果显示实验组骨水泥渗透厚度高于对照组,差异均具有统计学意义(P＜0.05). 结论 骨水泥振动器能够使骨水泥在骨髓腔内弥散更加均匀,能够促进骨水泥向骨小梁内渗透,从而增加骨水泥与骨小梁之间的微嵌合.     

骨水泥分布模式对I、II期Kümmell病经皮椎体后凸成形术疗效的影响

目的回顾性研究骨水泥分布模式对I、II期Kümmell病经皮椎体成形术疗效的影响。方法根据骨水泥在椎体内的分布形态,将85例接受经皮椎体成形术的Kümmell病患者分为A组(团块组)和B组(团块+嵌插组),比较两组患者骨水泥注入量、渗漏率、手术前与手术后、术后3月、6月、1年的VAS评分、ODI指数变化。结果 B组患者骨水泥注入量显著多于A组,两组骨水泥渗漏率无明显差异,两组患者术后VAS及ODI评分较术前明显改善,但术后3月、6月、1年时B组VAS及ODI评分明显优于A组。结论 PKP是治疗I、II期Kümmell病的有效方法,骨水泥分布模式是影响PKP术后疗效的重要因素,团块状+嵌插样骨水泥分布模式效果好于团块状分布。     

利奈唑胺骨水泥在关节置换术后感染治疗中应用的系列探索研究之一——利奈唑胺骨水泥的物理、力学性能研究

目的：探讨利奈唑胺骨水泥物理和力学性能改变,以指导利奈唑胺骨水泥在治疗人工关节置换术后感染中的临床应用。方法根据在40 g骨水泥中加入不同剂量的利奈唑胺,将样本共分成8个组,每组测定5个样本,8组分别是：Ⅰ组为对照组,不加抗生素,第Ⅱ到第Ⅷ组加入抗生素的量分别为1.2、2.4、3.6、4.8、6.0、7.2及8.4g。分别测定各组面团期时间、压缩强度、弯曲模量和弯曲强度。结果各组面团时间在2′50″～3′40″之间。随着抗生素剂量的增加,面团时间也随之增加。各组的压缩强度、弯曲模量和弯曲强度均优于ISO 5833标准,且有统计学差异（ P＜0.05）,Ⅱ组的压缩强度、弯曲模量和弯曲强度与对照组没有统计学差异,但高于其他各组,与其他各组间有统计学差异。而第Ⅷ组的压缩强度、弯曲模量和弯曲强度均低于其他各组,且有统计学差异。结论面团时间随着利奈唑胺剂量的增加而增加。如果利奈唑胺骨水泥用于预防性使用,则每40 g骨水泥中最多可以加入1.2g利奈唑胺,否则会影响骨水泥的强度。如果利奈唑胺骨水泥用于制作占位器,在每40 g骨水泥中最多不要加入超过7.2 g的利奈唑胺,不至于太影响骨水泥占位器的强度,但是加入的最佳剂量是多少,本系列实验的另一部分会有详细交代。     

Evaluation of Intraosseous Pressure during Pelvic Percutaneous Cement Injection: An In Vitro Study in Swine

BackgroundA minimally invasive procedure for symptomatic pelvic bone metastasis is a feasible option for advanced cancer patients, and bone cement injection plays an essential role. Pulmonary embolism caused by thrombus, fat, or tumor emboli is a major complication related to bone cement injection, and increasing intraosseous pressure is a predisposing factor. This study aimed to quantify the degree of pressure change in the pelvic bone during percutaneous bone cement injection and investigate whether there is a significant decrease in intraosseous pressure when a decompressive route is additionally established.MethodsBone cement injection into the acetabulum of swine pelvises by simulating the actual surgical procedure in terms of the injection method, bone cement, and surgical instruments was performed while recording the intraosseous pressure. Twenty swine pelvises were used and grouped into a decompression group and a non-decompression group. Bone cement injection and pressure measurement were conducted in the same way in both groups, but an additional decompressive route was established for each pelvis in the decompression group. Continuous variables were compared using the Mann-Whitney test.ResultsThe mean amount of injected bone cement was 19.8 mL and 20.3 mL and the mean speed of bone cement injection was 0.14 mL/sec and 0.12 mL/sec in the decompression group and the non-decompression group, respectively. The mean peak intraosseous pressures was 10.5 kPa with decompression and 37.8 kPa without decompression, and the difference was statistically significant (p < 0.01).ConclusionsIntraosseous pressure during bone cement injection into swine pelvises was similar to that during vertebroplasty or kyphoplasty. When the additional decompression route was established, the intraosseous pressure decreased to one third the level.