A new hip epiphyseal prosthesis: design revision driven by a validated numerical procedure

An innovative epiphyseal device has been recently proposed claiming an effective bone-prosthesis load transfer and a nearly physiological bone stresses distribution. However preliminary experimental tests showed a 23% weakening of the femoral neck after implantation. Aim of this study was to revise the prosthesis geometry with the goal of enhancing the femoral neck strength after implantation, while maintaining unchanged the initial conceptual design. To this aim, the risk of femoral neck fractures, prosthesis fractures, aseptic loosening and excessive bone resorption were addressed through a validated finite element procedure following a systematic approach. The initial prosthesis geometry was revised to reduce each investigated failure risk below the threshold of acceptance (100%). The new geometry was re-assessed to verify the effectiveness of the revision. The first design was predicted to locally induce high bone strains and cement stresses, which translated in a risk of bone and cement failure exceeding the threshold of acceptance (>100%). The revised design preserved a good stability of the device, contemporary reducing the risk for bone (45%) and cement (60%) failure. If results will be confirmed by statistical and clinical experimentations, current clinical indications for hip epiphyseal devices might be extended.     

生物型自锁式人工髋关节假体的改良设计

BACKGROUND: Hip prosthesis needs to meet the good structural compatibility with femoral bone marrow cavity and the biomechanical properties of the original bone tissue. However, the difference of individual anatomical characteristics and the stress concentration in the local area after replacement directly affect postoperative combination of femoral prosthesis stem, force flow transfer and femoral reconstruction, and finally result in aseptic loosening of hip joint in some patients.     

人工股骨柄的力学研究现状

背景：临床表明,全髋关节重建涉及假体、骨水泥和股骨整体的应力分布,针对减少各个组件的应力以减少置换关节失效风险研究有了很大的进展。 目的：对髋关节置换后各组件应力分布的研究现状及进展作一综述。 方法：应用计算机检索CNKI,EI Village和ELSEVER数据库中2001-01/2011-01关于髋关节置换和股骨柄应力的文章,在标题和摘要中以“股骨柄,应力,全髋关节置换”或“stem,prosthesis,stress,Total Hip Replacement”为检索词进行检索。入选34篇文献和2本书籍进行综述。 结果与结论：人工髋关节固定需亟待解决的关键问题是髋关节置换后各组件应力非均匀传递而引起的界面剪滞效应,并将最终导致界面松动失效。研究股骨-柄松动原因和增强股骨-柄界面的自锁能力,应是提高人工髋关节的稳定性和延长置换后髋关节寿命的发展方向。     

经后外侧入路小切口全髋关节置换治疗股骨颈骨折

背景：全髋关节置换已成为老年人创伤性股骨颈骨折常见的治疗方式之一,小切口微创方式可减少手术创伤及患者痛苦,便于老年患者假体置换后早期康复。 目的：探讨经后外侧入路小切口行全髋关节置换后治疗股骨颈骨折的临床效果。 方法：回顾性分析25例创伤后股骨颈骨折(Garden Ⅲ、Ⅳ型)患者资料,均行经后外侧入路小切口全髋关节置换。 结果与结论：25例患者随访≥6个月。置换后复查X射线示假体位置良好;1例出现脱位,处理后未再发生脱位;1例下肢不等长,不影响行走。置换后9个月Harris评分平均85.7。置换后未发生感染、神经损伤、假体松动、假体周围骨质情况及深静脉血栓形成。说明经后外侧入路小切口全髋关节置换具有创伤小、人工关节稳定性强、患者恢复时间短等优点,适合老年股骨颈骨折(Garden Ⅲ、Ⅳ型)患者。     

In vitro assessment of strength, fatigue durability, and disassembly of Ti6Al4V and CoCrMo necks in modular total hip replacements

Modularity in total hip replacement offers advantages with regard to biomechanical adjustments and leg lengths. Recently, modular femoral necks were introduced as an added advantage to head modularity permitting further adjustments in femoral version as well as offset and ease of revision. Currently, most necks are made of Ti6Al4V for which cases of in vivo fractures and inseparable neck-stem junctions have been reported. Therefore, we investigated CoCrMo head-Ti6Al4V stem hip replacements with necks made of CoCrMo as an alternative to Ti6Al4V. We compared the two materials with respect to (1) compressive load bearing capacity; (2) fatigue durability; and (3) component distraction. We performed in vitro fatigue-pull-off, microscopy, fatigue durability and compression investigations. The CoCrMo neck showed a load bearing capacity of 18 kN, 38% higher than 13 kN for the Ti6Al4V neck. A fatigue load of 11.2 kN for 1 million cycle failure was achieved with CoCrMo translating into nearly 1000 times longer fatigue life compared to Ti6Al4V necks. The neck-stem distraction force showed large statistical variation and was similar for both neck materials. Overall, the results suggest a superiority of CoCrMo over Ti6Al4V as neck material with regard to mechanical behavior. However, the corrosion behavior was not appropriately assessed and necessitates additional investigations.     

Delbet Ⅱ型儿童股骨颈骨折不同内固定方式的有限元分析

背景：儿童DelbetⅡ型股骨颈骨折后股骨头坏死率较高,有限元法已广泛应用于研究成人股骨颈骨折内固定后的稳定性,但儿童股骨颈骨折的相关分析较少。目的：研究3种不同内固定方式治疗DelbetⅡ型儿童股骨颈骨折的生物力学性能。方法：选择1例8岁儿童健康志愿者为研究对象。CT扫描患儿股骨近端影像数据导入Mimics 17.0,在Geomagic 14.0,Cero 3.0,Hyper Works13.0中建立3种内固定方式治疗DelbetⅡ型儿童股骨颈骨折的有限元模型,分别为空心钉模型（CS模型）、空心钉联合克氏针模型（CS+K模型）、锁定钢板模型（LP模型）,观察3种模型的内固定应力、骨骺应力及骨折断端相对位移。结果与结论：（1）CS+K模型骨折端和股骨头内的应力显著大于CS模型、LP模型（P <0.001）;LP模型的股骨侧应力显著大于CS+K模型、CS模型（P<0.001）;（2）CS模型的相对位移量显著大于CS+K模型和LP模型（P<0.001）;（3）LP模型的骺板平均应力显著大于CS+K模型、CS模型（P<0.001）;（4）结果表明,空心钉联合克氏针固定...     

股骨侧远端生物固定假体在高龄患者全髋关节翻修中的应用

背景：对高龄患者行人工全髋关节翻修时如何正确选择股骨侧假体固定方式,可否应用组配式股骨假体处理此类难题? 目的：验证股骨侧生物固定型假体在老年人全髋翻修后的效果。 方法：采用远端固定生物型股骨假体对11例75岁以上股骨侧假体松动患者进行翻修。11例股骨骨缺损根据Paprosky分型,Ⅰ型2髋,Ⅱ型2髋,ⅢA型7髋。 结果与结论：11例患者均随访16个月以上,患者Harris评分从翻修前的37分(22~49分)改善至随访结束时的89分(78~92分),优良率>90%,无患者发生再次松动。翻修后X射线片显示假体周围骨质密度和厚度明显增加。提示远端固定生物型假体可在股骨远端髓腔内获得可靠的轴向及抗旋转初始稳定性,尤其适用于伴有近端骨缺损的高龄患者的翻修治疗。     

S-ROM股骨柄假体的设计特征与初次全髋置换

背景：目前尚缺少S-ROM股骨柄假体应用于初次全髋置换后疗效的报道。 目的：探讨S-ROM股骨柄假体在初次全髋置换中的应用。 方法：纳入2009-04/2011-05于苏州大学附属第一医院骨科采用S-ROM股骨柄假体行初次全髋置换的71例(75髋)患者,置换后评估髋关节功能及假体的生物学固定效果。 结果与结论：纳入的71例患者全髋置换后X射线片显示股骨柄假体的初始固定均符合优良标准。无感染、骨折、脱位、深静脉血栓及神经损伤等并发症。置换后半年,Harris评分恢复至(93.8±3.5)分,X射线片未见假体松动征。说明S-ROM股骨柄假体具有设计合理,可调控性强,符合患者解剖等优点,可有效改善患者髋关节功能。关键词：全髋关节置换;S-ROM假体;假体特征;组配;髋关节功能;生物学固定 缩略语注释：VAS：visual analogue scale,目测类比评分 doi:10.3969/j.issn.1673-8225.2012.17.006     

The morphogenesis of porcine femoral head mammillary processes: A structural mechanism of biomechanical stability

The capital femoral physis is a growth plate located between the head of the femur and femoral neck, which forms a temporary joint where growth plate cartilage is converted to bone by endochondral ossification. The bone-cartilage-bone interface develops a unique radial pattern of interdigitating mammillary processes that interlock the femoral head with the metaphysis, increasing biomechanical stability. The arrangement of these mammillary processes may not be a random occurrence and likely serves to provide mechanical mechanisms to enhance biomechanical stability. In this study, we provide a qualitative and quantitative analysis of porcine femoral head mammillary processes and focus on the analysis of six key points of development: the epiphyseal tubercle, epiphyseal cupping, growth plate slope angles, expansion of the epiphyseal subchondral bone plate, epiphyseal elongation, and the emergence of smaller, radially arranged mammillary processes. We introduce a metric of surface roughness analysis to quantify mammillary processes and apply it to analyze the development of the observed radial pattern of peripheral mammillary processes from birth to adolescence. We hypothesized that these processes develop to form a radial pattern with some degree of periodicity beginning relatively early in development of the joint and increase in prominence with age and weight of the animal. These findings may have important implications in the early diagnosis and treatment of the hip disorder slipped capital femoral epiphysis (SCFE). Underdevelopment of femoral head mammillary processes may reduce joint stability and could be a risk factor in SCFE.     

人工髋关节置换后假体周围骨折的治疗

背景：股骨假体周围骨折是人工髋关节置换后常见的并发症之一,并且发病率在不断增加,改进股骨假体周围骨折的治疗方法及技术成为研究的课题之一。 目的：明确各种内固定对于人工髋关节置换后假体周围骨折的治疗效果,为治疗技术的改进以及患者生活质量的改善提供理论参考信息。 方法：分别对人工髋关节置换治疗中以及治疗后并发假体周围骨折的影响因素及内固定治疗方法进行实验数据分析,重点分析形状记忆合金环抱器和锁定钢板内固定治疗人工髋关节置换后假体周围骨折的临床效果,同时比较不同内固定方法对假体周围骨折的治疗效果。 结果与结论：患者的性别、年龄、假体的类型以及假体的稳定性均为人工髋关节置换后周围假体骨折发生的危险因素,非骨水泥型假体发生骨折的风险高于骨水泥型假体发生骨折的风险。对于人工髋关节置换后周围假体骨折治疗方法的选择,形状记忆合金环抱器内固定不损害假体周围骨皮质,并且具有固定稳固、操作简单、创伤较小、并发症少等优点,而锁定加压钢板结合钢缆内固定具有创伤小、对骨折断端血供干扰小、固定稳固等优点,2种内固定治疗均可以获得较好的临床治疗效果,但是相比较而言,锁定加压钢板内固定比形状记忆合金环抱器内固定治疗获得更好的临床效果。     

An experimental analogue to model the fibrous tissue layer in cemented hip replacements

Fibrous tissue at the bone-cement interface of cemented joint replacements has been reported frequently in cases of revisions made necessary by aseptic loosening. This work describes the development of in vitro specimens suitable for biomechanical modeling of cemented femoral hip replacements with a fibrous tissue layer at the bone-cement interface. In particular, a series of uniaxial compression tests were performed on silicone elastomer specimens to identify a suitable analogue with similar mechanical characteristics to those reported for the fibrous tissue layer. A method was developed to apply the silicone elastomer at the bone-cement interface. This was examined for two types of cemented hip replacements implanted in composite femurs. The selected thickness of the elastomer layers was in the range of those found in clinical cases of aseptic loosening. Specimens produced by these methods could be used in preclinical biomechanical tests (such as stability or stress shielding tests) to assess the effects of a soft-tissue layer, to model in vitro a long-term-implant scenario, and to provide validation for similar finite element studies.     

Removal of bone cement from the femoral canal using an acoustic emission-controlled milling device

The removal of bone cement from the femoral canal in the case of hip prosthesis loosening takes a considerable amount of time and carries the additional risk of complications, thus risking bone damage and perhaps even endangering the successful reimplantation of a new prosthesis. We have demonstrated experimentally that the milling of bone and bone cement produces acoustic emission waves of different intensity. These waves can be measured by a commercial acoustic emission transducer. This method enables us to control a milling device during the removal of bone cement from deep in the femoral canal, avoiding the serious damage to the bone and thus enabling a new prosthesis to be reimplanted.     

Tri-Lock骨保留型股骨柄假体的设计特征与临床应用

背景：新一代Tri-Lock BPS型股骨柄假体在原有设计基础上得到进一步改进,目前尚少有报道总结其设计特征及手术技巧。 目的：总结Tri-Lock BPS型股骨柄假体的设计特征及其在全髋关节置换中的应用。 方法：选择Tri-Lock BPS柄行全髋关节置换的患者9例(10髋),其中股骨头坏死8例,创伤性关节炎1例。置换前后的髋关节功能和置换后股骨柄假体的生物学固定分别按Harris标准和Engh标准评定,置换后股骨柄假体的初始固定质量按Healy标准评定,分析透亮线、骨溶解的发生率,分别按Delee和Gruen分区描述髋臼和股骨侧的骨长入,按D’Antonio法测量股骨柄假体的下沉,股区痛则采用目测类比评分10分制评定。 结果与结论：10髋置换后X射线片显示股骨柄假体的初始固定均符合优良标准。凡手术满3个月的患者,髋关节功能(Harris评分)均可恢复至平均92分(85~96分),无主诉存在股区痛,无X射线显示的假体松动征。结果证实,Tri-Lock BPS型假体设计更符合人体解剖特征,髋关节功能恢复快,骨量保留多等优点。     

双极人工股骨头治疗老年帕金森患者股骨颈骨折

背景：帕金森患者由于肌力不平衡等原因更容易跌倒,发生股骨颈骨折的风险高。 目的：观察双极人工股骨头置换对老年帕金森病合并股骨颈骨折患者的治疗效果。 方法：回顾分析14例帕金森病合并股骨颈骨折行双极人工股骨头置换患者的临床资料,共14髋,Hoehn-Yahr分级Ⅰ期3例,Ⅱ期4例,Ⅲ期5例,Ⅳ期2例,置换时年龄62~83岁。采用Harris评分、Fugl-Meyer量表及统一帕金森病评定量表相结合的方法进行随访。 结果与结论：随访1~6年,14例患者置换后Harris评分平均85.4分,优于置换前平均22.3分(P < 0.05),Fugl-Meyer评分置换后平均81.6分,优于置换前平均52.5分(P < 0.05),统一帕金森病评定量表评分置换前后差异无显著性意义,帕金森病情控制稳定。无关节松动、脱位等并发症发生。早中期随访结果显示,在有效神经内科药物控制下,双极人工股骨头置换是一种安全、有效治疗Hoehn-YahrⅠ~Ⅳ期帕金森病合并股骨颈骨折患者的方法,置换后髋关节功能与帕金森病病情控制相关。     

骨小梁结构髋臼杯和实体结构髋臼杯的三维模型仿真分析

文题释义： 骨小梁结构：骨组织包括皮质骨和松质骨，松质骨由一系列小梁骨组成。骨小梁在人体内分布广，呈疏松多孔的网状结构，骨的这种结构使得骨能够承受来自各个方向的载荷，并将载荷分散化，减少集中载荷对骨的不良影响。 有限元分析：有限元分析是一种数值分析方法，它的根本思想是离散化。即利用简单而又相互作用的元素(即单元)，就可以用有限数量的未知量去逼近无限未知量的真实系统。有限元数值模拟技术是提升产品质量、缩短设计周期、提高产品竞争力的一项有效手段，所以，随着计算机技术和计算方法的发展，有限元法在工程设计和科研领域得到了越来越广泛的重视和应用，已经成为解决复杂工程分析计算问题的有效途径。 背景：髋关节置换是治疗股骨头坏死、骨性关节炎、髋关节发育不良以及老年股骨颈骨折等髋关节疾病最有效的方法，因此有必要对髋关节置换的生物力学行为展开研究。 目的：采用有限元仿真的方法模拟髋关节置换后骨小梁结构髋臼杯和实体结构髋臼杯模型的接触应力和米氏应力大小和分布情况，分析其对假体及髋关节的影响。 方法：通过3-Matic Research 11.0软件设计了2种不同结构的髋关节假体组件模型：骨小梁结构髋臼杯和实体结构髋臼杯模型。并将设计好的模型经Hypermesh 14.0软件划分网格并赋予材料属性，最后导入有限元分析软件Abaqus 6.13软件中仿真分析，比较相同状态下2种髋臼杯的应力值和应力分布情况。 结果与结论：骨小梁结构髋臼杯的应力呈散点状分布，分布范围广。实体结构髋臼杯容易出现应力集中现象，应力分布集中在受力点附近。骨小梁结构髋臼杯相对于实体结构髋臼杯而言，应力分布范围更大，应力分布更均匀，从而可以减轻髋关节假体之间的磨损，降低髋关节假体发生无菌性松动的风险。 ORCID: 0000-0003-4612-6111(王晖) 中国组织工程研究杂志出版内容重点：人工关节；骨植入物；脊柱；骨折；内固定；数字化骨科；组织工程     

重建型交锁髓内钉与动力髋螺钉治疗股骨复杂性骨折的随访比较

背景：骨折后植入物内固定主要有髓内钉和钢板两种,如何合理选择适宜的内固定器械,对临床疗效及并发症等问题至关重要。 目的：重建型交锁髓内钉和动力髋螺钉钢板治疗股骨复杂性骨折的随访疗效比较。 方法：回顾性分析70例股骨干骨折合并同侧股骨颈骨折、转子间骨折、转子下骨折,股骨干多段骨折患者的临床资料,内固定植入物有重建型交锁髓内钉和动力髋螺钉钢板两种。 结果与结论：全部患者随访3个月以上。重建型交锁髓内钉组的早期功能恢复、骨折愈合时间相对优于动力髋螺钉组。在并发症方面动力髋螺钉易出现髋内翻和内固定失败,重建型交锁髓内钉易出现锁钉松动。在切口感染和脂肪栓塞综合征发生率方面,两者差异无显著性意义。故可认为重建型交锁髓内钉具有同时静力加动力固定两处骨折的功能,符合生物力学重建原则和骨折愈合快等优点,是一种优于动力髋螺钉的有效内固定器械。     

髋关节表面置换术中可视化虚拟技术建立股骨头假体植柄通道的模拟研究

目的：通过计算机辅助对股骨头假体植柄通道的模拟研究,为人工全髋关节表面置换术股骨头假体植入方案提供更为科学的评估方法和预测手段。方法：选择无明显髋关节疾病的15具成人尸体标本,对整个骨盆进行连续CT扫描,将CT原始数据导入Mimics 10．1软件,重建出股骨近端三维模型。通过计算股骨头中心和股骨近端中心线,建立股骨颈轴线并确定股骨头假体最佳植柄通道,进行虚拟植入和三维可视化分析。结果：各维度观察股骨头假体植柄通道通过股骨头中心,位于股骨颈的中央。股骨头定位针模拟植入后假体柄干角与术前颈干角相比呈轻度外翻位,侧方偏移和水平偏移度较小,达到预期植柄方位的要求。结论：计算机辅助可以准确建立股骨头假体植柄通道并进行可视化分析,为个体化髋关节表面置换术提供了科学的评估方法和预测手段。     

模拟全髋关节置换术后两种假体的应力对比分析

对比分析置入解剖型假体和置入传统型假体应力遮挡效应,为临床提供生物力学基础。随机取5个为模拟全髋关节置换术以（北京普鲁士钢研外植入物有限公司）传统型假体置入的股骨组,随机取5个以（德国LINK公司）保留股骨颈解剖型假体置入股骨组。首先在正常股骨标本的各测点上黏贴电阻应变片,进行应变电测量之后,待标本在室温不受力状态下放置24h后,对正常股骨标本分别置入传统型假体、保留股骨颈解剖型假体,分别测出置入传统型假体组和解剖型假体组股骨各测点的应变值,计算各测点的应力值,根据应力遮挡率计算公式,计算应力遮挡率值。置入传统型假体组股骨标本近端1～10号测点应力遮挡率值大于置入解剖型假体组股骨标本近端1～10号测点应力遮挡率值,差异显著（P＜0．05）。解剖型假体和传统型假体具有不同的防应力遮挡效果,保留股骨颈解剖型假体防应力遮挡效果显著。     

股骨近端假体周围骨折锁定加压接骨板的设计

目的 探索适用于国人全髋关节置换术(THA)术后股骨近端假体周围骨折(PPFF)内固定的锁定加压接骨板(LCP)的设计。方法 (1)回顾性分析2012年9月—2013年12月南京中医药大学附属常州市中医医院骨科收治首次行THA治疗的90例患者的影像学资料。在90例患者术后髋关节侧位X线片上测量股骨假体近端1/2假体柄后边缘与股骨后方外皮质、远端1/2股骨假体柄前边缘与股骨前方外皮质的最小和最大垂直距离。(2)选取20具股骨标本,测量股骨标本长度和周径。将20具股骨标本植入股骨假体,建立股骨假体模型;对其中5具标本模型进行宝石能谱CT扫描和三维重建,测量股骨假体近端1/2假体柄后边缘与后方股骨外皮质、远端1/2假体柄前边缘与前方股骨外皮质间垂直距离,测量股骨假体近端1/2和远端1/2垂直距离＞6 mm的股骨长度,测量股骨中段侧方的弧度。(3)依据90例患者和5具股骨假体模型的测量数据设计并数字化定制LCP。采用定制LCP固定5具股骨假体模型,通过大体和影像学观察LCP近段锁定螺钉与假体的关系,调整可能与假体接触的锁定螺钉的角度;再采用调整后的LCP固定10具股骨假体模型,观察LCP近段锁定螺钉与假体的关系,确定LCP的设计方案。结果 (1)90例患者术后髋关节侧位X线片测量结果:股骨假体近端1/2假体柄后边缘与股骨后方外皮质的垂直距离,最小(11.26±3.58)mm,最大(17.97±6.94)mm;远端1/2假体柄前边缘与股骨前方外皮质之间的垂直距离,最小(9.18±2.32)mm,最大(14.22±3.10)mm。(2)20具股骨标本的股骨长度为(41.67±0.24)cm,周径为(9.19±0.74)cm。股骨假体模型CT测量结果:假体近端1/2假体柄后边缘与股骨后方外皮质的垂直距离为(12.36±3.24 )mm;假体远端1/2假体柄前边缘和股骨前方外皮质的垂直距离为(8.14±1.21)mm。假体近、远端1/2与股骨外皮质垂直距离＞6 mm的股骨长度分别为(69.20±4.53)mm 和(57.31±3.82)mm。(3)LCP设计方案:LCP与假体近端1/2对应的部分设计3枚向后内成一定角度的锁定螺钉,对应3个锁定孔,分布于LCP中轴线偏后,向后内方向;与假体远端1/2对应的部分设计3枚向前内成一定角度的锁定螺钉,对应的3个锁定孔,分布于LCP中轴线偏前,向前内方向。采用设计、定制LCP固定股骨假体模型,LCP与股骨侧方弧度一致,锁定螺钉在股骨假体的后方或前方均实现双层皮质固定,角度合适。结论 根据国人资料设计、定制LCP,在股骨假体模型上获得有效的固定空间,为THA后PPFF的处理提供可行方案,但临床应用效果有待进一步验证。     

Design of a biomimetic polymer-composite hip prosthesis

A new biomimetic composite hip prosthesis (stem) was designed to obtain properties similar to those of the contiguous bone, in particular stiffness, to allow normal loading of the surrounding femoral bone. This normal loading would reduce excessive stress shielding, known to result in bone loss, and micromotions at the bone-implant interface, leading to aseptic prosthetic loosening. The design proposed is based on a hollow substructure made of hydroxyapatite-coated, continuous carbon fiber (CF) reinforced polyamide 12 (PA12) composite with an internal soft polymer-based core. Different composite configurations were studied to match the properties of host tissue. Nonlinear three-dimensional analysis of the hip prosthesis was carried out using a three-dimensional finite element bone model based on the composite femur. The performance of composite-based hip and titanium alloy-based (Ti-6Al-4V) stems embedded into femoral bone was compared. The effect of core stiffness and ply configuration was also analyzed. Results show that stresses in composite stem are lower than those in Ti stem, and that the femoral bone implanted with composite structure sustains more load than the one implanted with Ti stem. Micromotions in the composite stem are significantly smaller than those in Ti stem over the entire bone-implant surface because of the favorable interfacial stress distribution.