A comparative analysis of different treatments for distal femur fractures using the finite element method

The main objective of this work is the evaluation, by means of the finite element method (FEM) of the mechanical stability and long-term microstructural modifications in bone induced to three different kinds of fractures of the distal femur by three types of implants: the Condyle Plate, the less invasive stabilization system plate (LISS) and the distal femur nail (DFN). The displacement and the stress distributions both in bone and implants and the internal bone remodelling process after fracture and fixation are obtained and analysed by computational simulation. The main conclusions of this work are that distal femoral fractures can be treated correctly with the Condyle Plate, the LISS plate and the DFN. The stresses both in LISS and DFN implant are high especially around the screws. When respect to remodelling, the LISS produces an important resorption in the fractured region, while the other two implants do not strongly modify bone tissue microstructure.     

Three-dimensional design optimisation of patient-specific femoral plates as a means of bone remodelling reduction

Previous investigations into the optimisation of internal plates have mostly focused on the material properties of the implant. In this work, we optimise the shape, size and placement of the plate for successfully minimising bone remodelling around the implant. A design optimisation algorithm based on strain energy density criterion, combined with the finite element analysis, has been used in this study. The main optimisation goal was to reduce this change and keep it close to the conditions of an intact femur. The results suggest that the anterolateral side of the bone would be the optimum location for the plate, as for the geometry, the optimum moves towards having a thick, wide and short plate. These important results could be directly applicable to orthopaedic surgeons treating a femur fracture with internal plates. Since the optimisation algorithm remains the same for any patient, this advancement provides the surgeon with a tool to minimise the post surgery remodelling by trying to maintain the natural structure of the bone.     

两种方法治疗桡骨远端骨折的疗效比较研究

目的:比较采用T形钢板内固定和闭合复位石膏外固定这两种方法治疗桡骨远端骨折的疗效研究。方法:选取我院2008年3月至2011年12月间的76例桡骨远端骨折患者,并按照治疗方法不同分为2组,41例患者进行T形钢板内固定,其余35例患者进行复位后石膏外固定。并借助X线对比分析桡骨远端骨折复位前后及临床愈合时桡骨腕关节的掌倾角、尺偏角及桡骨轴向缩短长度变化等数据,并根据改良的Shea评定法对临床疗效进行比较。结果:针对桡骨远端不稳定型骨折的患者,T形钢板内固定组的优良率要优于石膏外固定组的疗效(P<0.05);而对于稳定性桡骨远端骨折的患者,两组之间的优良率没有明显差异(P>0.05)。结论:对于桡骨远端不稳定骨折的患者,应优先选择T形钢板内固定手术方法,而对于稳定性骨折患者这两种治疗方法均可采用。     

LISS钢板治疗股骨远端骨折有限元建模及分析

目的建立LISS-DF治疗股骨远端骨折近端螺钉不同单双皮质固定的三维有限元模型,并进行初步生物力学分析。方法提取CT图片相关数据,利用自行编写程序生成命令流文件,建立完整股骨以及16个不同LISS-DF治疗股骨远端AO分型33-A3型骨折的实体模型（钢板和股骨不接触、螺钉分别固定于钢板和股骨）,进行网格划分。分析不同载荷作用下完整股骨和LISS钢板近端螺钉全双皮质固定治疗骨折的模型受力状况。结果建立了相关的有限元模型。不同载荷作用下,LISS钢板近端螺钉全双皮质固定模型和完整股骨的应力集中均位于股骨颈内侧和股骨干外侧中下1/3处。相同载荷作用下,LISS钢板近端螺钉全双皮质固定模型的股骨颈部最大等效应力值略减小,股骨干最大等效应力值明显减小。结论研究建立的三维有限元模型,为应用LISS治疗股骨骨折的生物力学分析提供了良好的实验平台和基础。从生物力学角度而言,LISS-DF近端螺钉全双皮质固定为治疗股骨远端复杂骨折的有效方法。     

微创经皮LCP 接骨术治疗老年股骨近端粉碎骨折

目的:本研究通过观察微创锁定钢板接骨术治疗老年股骨近端粉碎骨折临床效果,旨在找出最佳治疗方式。方法:自2007年12月～2010年03月,应用股骨近端锁定加压钢板治疗老年股骨近端粉碎骨折23例。记录术中出血量、手术时间,术后并发症、骨折愈合时间及最后一次随访时功能恢复情况。结果:骨折临床愈合时间为12～28周,平均16周。除1例患者髋内翻畸形,1例锁定加压钢板断裂外,其他患者均达到骨性愈合。结论:股骨近端锁定钢板具有创伤小、固定可靠、骨折愈合快、功能恢复满意的特点,尤其适用于老年股骨近端粉碎骨折。     

锁定板微创技术治疗老年人股骨远端骨折的临床效果观察

目的:探讨锁定板MIPO技术治疗老年人股骨远端骨折的临床效果。方法:回顾性分析2009年1月-2012年12月运用锁定板MIPO技术治疗老年人股骨远端骨折患者的临床资料,评估骨折类型、骨折愈合时间、6个月时的膝关节活动度和膝关节功能评分及临床并发症的发生情况。结果:共纳入33例老年人股骨远端骨折患者,平均年龄72岁,其中2例随访失败。87%的股骨远端骨折是关节外骨折;骨折平均愈合时间为12.56(8~29)周;术后6个月时平均活动范围超过105°:伸0°~30°,屈90°~140°;术后6个月的平均膝功能评分89.5;治疗过程中无植入失败、骨折不愈合和感染发生;术后早期发生下肢深静脉血栓(DVT)7例(22.6%),均在膝关节水平以下。结论:锁定板结合MIPO技术是一种治疗老年人股骨远端骨折安全有效的方法,但要注意预防术后DVT的发生。     

掌侧DVR^TM-Anatomic钢板内固定治疗桡骨远端不稳定骨折20例临床疗效研究

目的：探讨切开复位掌侧解剖锁定加压钢板（DVR-Anatomic）内固定在桡骨远端骨折治疗中的临床疗效。方法：对20例桡骨远端骨折患者经掌侧切口进行切开复位、DVR^TM-Anatomic内固定,并随访其骨折愈合情况及远期功能效果。结果：所有病例均获随访,平均随访时间为11.3个月（3～20个月）。所有骨折均获骨性愈合,愈合时间为65d（56～84 d）,无伤口感染、骨不连、内固定断裂脱出、伸指受限等并发症。运用DASH调查表和PRWE评分了解上肢的症状及从事日常活动的能力,且在末次随访时两种评分系统的平均值分别为9.58±14.87和13.73±18.42。结论：对于桡骨远端不稳定骨折掌侧入路DVR-Anatomic钢板治疗桡骨远端骨折临床疗效满意,值得推广。     

锁定加压钢板行微创技术治疗老年性股骨远端骨折临床疗效分析

目的:评价用锁定加压钢板行微创技术治疗老年性股骨远端骨折的临床疗效。方法:自2012年1月到2015年6月间,我院用锁定加压钢板行微创技术治疗27例60岁以上老年性股骨远端骨折患者(其中1例为双侧),通过观察患者伤口愈合情况、骨折愈合情况及相关并发症,并采用Kolmert评分标准评价其临床效果。结果:本组27例患者均获得随访,其中1例患者(单侧)在术后25 d死亡,其余病例随访6-30月,平均14.7月,术后切口有1例延迟愈合,余均一期愈合,骨折在末次随访均骨性愈合,未见骨折移位、内固定物失效、骨折畸形愈合、骨折不愈合等不良并发症,根据Kolmert评分标准,优10例,良13例,可3例,差1例,优良率为85%。结论:锁定加压钢板行微创技术治疗老年性股骨远端骨折可达到固定牢固、能早期功能练习、术后并发症少、术后效果满意的疗效。     

微创经皮钢板接骨术与Henry入路钢板内固定治疗桡骨远端骨折的疗效观察

目的:研究微创经皮钢板接骨术与Henry入路钢板内固定治疗桡骨远端骨折的疗效。方法:选取2013年2月到2014年2月我院收治的桡骨远端骨折患者86例,按照随机数字表法将患者分为Ⅰ组和Ⅱ组,每组43例,Ⅰ组患者给予微创经皮钢板接骨术治疗,Ⅱ组患者给予Henry入路钢板内固定治疗,术后随访患者1年,比较两组临床疗效。结果:Ⅰ组手术时间、术中出血量显著优于Ⅱ组,两组比较差异具有统计学意义(P0.05);Ⅰ组术后1年DASH评分显著优于Ⅱ组,两组比较差异具有统计学意义(P0.05);两组并发症比较无统计学意义(P0.05)。结论:微创经皮钢板接骨术治疗桡骨远端骨折具有较好的临床疗效,能缩短手术时间、降低术中出血量,改善患者上肢功能。     

LISS-DF近端螺钉不同固定方式的有限元分析

目的研究LISS-DF治疗股骨远端骨折近端螺钉不同固定方式对应力分布规律的影响,寻找符合生物力学原理的固定方式,为临床应用提供理论依据。方法在ANSYS9.0软件中建立LISS-DF钢板固定股骨远端骨折（AO/OTA33-A3型）的实体模型和有限元模型。在近端螺钉不同单、双皮质固定方式下,通过模拟生理应力做轴向加载实验并进行有限元计算和分析。结果1、3孔单2、4孔双皮质固定时,近端螺钉最大应力值在不同固定方式中最小为24.21975Mpa,位移值为0.131424um与其它固定方式相当且均较小,说明该固定方式可以取得较好的力学效果。结论近端螺钉靠近骨折端处双皮质固定,其余螺钉间隔单双皮质固定时,可以减少应力集中现象,得到更好的把持力,使固定更牢固,从而降低固定失败的风险性。     

逆行可膨胀髓内钉与锁定钢板治疗股骨远端骨折的疗效比较

目的:探讨比较运用逆行可膨胀髓内钉与股骨远端锁定钢板治疗股骨远端33A、33C1型骨折的疗效。方法:对2013年3月至2015年6月收治并符合纳入标准的43例股骨远端33A、33C1型骨折患者进行回顾性研究。按照不同的手术固定方式分为逆行可膨胀髓内钉组(n=18)和锁定钢板组(n=25),记录并比较两组手术时间、失血量、愈合时间及功能结果、术中及术后并发症。结果:所有骨折最终都获得愈合;逆行可膨胀髓内钉组在手术时间及失血量上都显著低于锁定钢板组,两组在愈合时间及功能评定方面无明显差异;5例开放性骨折的患者中1例出现浅表伤口感染,1例患者延迟愈合。结论:股骨远端逆行可膨胀髓内钉在获得与锁定钢板相当的骨折愈合时间及患肢功能的情况下,具有操作简单、手术时间短、失血量少等特点,对于股骨远端33A、33C1型骨折来说是一个较好的选择。     

3D打印股骨远端内侧个性化解剖型接骨板的研究进展

目前,比较复杂的股骨远端C3型骨折和膝外翻的矫形手术都需要应用到独立的股骨内侧接骨板。以往术者都是将对侧股骨的外侧接骨板进行预弯曲,以达到贴近骨骼自然形态的目的,而这种冷变形会改变接骨板的金相结构,进而破坏接骨板的生物力学,接骨板螺钉孔的位置有时也会影响到骨折的愈合情况。与传统制造技术相对比,3D打印技术作为"第三次工业革命"的核心技术,不必事先制造模具,不必在制造过程中去除大量的材料,也不必通过复杂的锻造工艺就可以得到最终产品,更适合于难加工材料的制造、外形设计检查、装配检验和快速反求工程等。本文将股骨远端内侧接骨板的个性化设计与3D打印技术相结合,从接骨板的应用、3D打印技术的现况及其应用于制作股骨远端内侧个性化解剖型接骨板的前景等方面进行了综述。     

Numerical analysis of an osseointegrated prosthesis fixation with reduced bone failure risk and periprosthetic bone loss

Currently available implants for direct attachment of prosthesis to the skeletal system after transfemoral amputation (OPRA system, Integrum AB, Sweden and ISP Endo/Exo prosthesis, ESKA Implants AG, Germany) show many advantages over the conventional socket fixation. However, restraining biomechanical issues such as considerable bone loss around the stem and peri-prosthetic bone fractures are present. To overcome these limiting issues a new concept of the direct intramedullary fixation was developed. We hypothesize that the new design will reduce the peri-prosthetic bone failure risk and adverse bone remodeling by restoring the natural load transfer in the femur. Generic CT-based finite element models of an intact femur and amputated bones implanted with 3 analyzed implants were created and loaded with a normal walking and a forward fall load. The strain adaptive bone remodeling theory was used to predict long-term bone changes around the implants and the periprosthetic bone failure risk was evaluated by the von Mises stress criterion. The results show that the new design provides close to physiological distribution of stresses in the bone and lower bone failure risk for the normal walking as compared to the OPRA and the ISP implants. The bone remodeling simulations did not reveal any overall bone loss around the new design, as opposed to the OPRA and the ISP implants, which induce considerable bone loss in the distal end of the femur. This positive outcome shows that the presented concept has a potential to considerably improve safety of the rehabilitation with the direct fixation implants.     

Numerical Simulation of Bone Plate with Fatigue Crack and Investigation of Attraction Hole for Retarding Crack Growth

Premature fracture of the bone plate caused by fatigue crack is the main failure mode in treating femoral shaft fracture. In order to improve the durability of the plate, this study proposed a crack attraction hole (CAH) to retard the crack propagation based on the fracture mechanics. In this paper, a numerical model of the femoral fracture internal fixation system was constructed, in which the femur was developed using a validated simplified model. First, the fatigue crack initiation location was defined at the stress concentration through static analysis. Next, with the joint simulation method of Franc3D and ABAQUS, the fatigue crack path in the bone plate was predicted. Meanwhile, the Paris parameters of Ti-6Al-4V obtained through experiments were encoded into Franc3D to calculate the crack propagation life. Finally, we considered the influence of CAH designs with different relative vertical distances (2.0, 3.0, and 4.0 mm) and diameters (1.5, 2.0, and 2.5 mm) on the crack propagation path and life of the bone plate. Additionally, the effects of all CAH configurations on the biomechanical performance of the bone plate fixation system were evaluated. The results indicated that the fatigue crack growth path in the bone plate is comparable to a straight line, and the crack growth rate significantly increases when the crack tip reaches the outer boundary of the plate. The findings suggest that the addition of CAH in the bone plate will lead to the deflection of the crack path and increase the fatigue life. Equally important, the improvement of the fatigue life was positively correlated with the diameter of CAH and negatively correlated with the relative vertical distance. In addition, the biomechanical properties of the bone plate system were slightly affected by CAH, substantiating the feasibility of this method. Finally, the comparative analysis verified that a CAH with a relative vertical distance of 3 mm and a diameter of 2 mm exhibited superior improvement in the comprehensive performance on the bone plate.     

中西医结合治疗桡骨远端骨折的临床分析

目的:探讨中西医结合治疗桡骨远端骨折的临床治疗效果。方法:选取本院收治的桡骨远端骨折患者60例,将其随机分为对照组和实验组,每组30例。对照组采用切开复位钢板螺钉固定方法治疗,实验组采用切开复位钢板螺钉固定加局部中药外敷治疗。观察和比较两组患者的骨折愈合时间、腕部功能恢复情况以及临床疗效。结果:与对照组比较,实验组患者的骨折愈合时间明显缩短,患肢腕部功能明显改善,差异具有统计学意义(P0.05);实验组的临床总有效率(76.66%)明显高于对照组(65.00%),差异具有统计学意义(P0.05)。结论:中西医结合治疗桡骨远端骨折能够有效缩短骨折愈合时间,明显改善患者的腕部功能,值得临床推广。     

The effect of muscle loading on the simulation of bone remodelling in the proximal femur

A large number of finite element analyses of the proximal femur rely on a simplified set of muscle and joint contact loads to represent the boundary conditions of the model. In the context of bone remodelling analysis around hip implants, muscle loading affects directly the spatial distribution of the remodelling signal. In the present study we performed a sensitivity analysis on the effect of different muscle loading configurations on the outcome of the bone remodelling simulation. An anatomical model of the femur with the implanted stem in place was constructed using the CT data of the Visible Human Project dataset of the National Institute of Health. The model was loaded with three muscle force configurations with increasing level of complexity. A strain adaptive remodelling rule was employed to simulate the post-operative bone changes around the implant stem and the results of the simulation were assessed quantitatively in terms of the bone mineral content changes in 18 periprosthetic regions of interest. The results showed considerable differences in the amount of bone loss predicted between the three cases. The simplified models generally predicted more pronounced bone loss. Although the overall remodelling patterns observed were similar, the bone conserving effect of additional muscle forces in the vicinity of their areas of attachment was clear. The results of this study suggest that the loading configuration of the FE model does play an important role in the outcome of the remodelling simulation.     

Influence of interface condition and implant design on bone remodelling and failure risk for the resurfaced femoral head

Resurfacing of the femur has experienced a revival, particularly in younger and more active patients. The implant is generally cemented onto the reamed trabecular bone and theoretical remodelling for this configuration, as well as uncemented variations, has been studied with relation to component positioning for the most common designs. The purpose of this study was to investigate the influence of different interface conditions, for alternative interior implant geometries, on bone strains in comparison to the native femur, and its consequent remodelling. A cylindrical interior geometry, two conical geometries and a spherical cortex-preserving design were compared with a standard implant (ASR, DePuy International, Ltd., UK), which has a 3° cone. Cemented as well as uncemented line to line and press-fit conditions were modelled for each geometry. A patient-specific finite element model of the proximal femur was used with simulated walking loads. Strain energy density was compared between the reference and resurfaced femur, and input into a remodelling algorithm to predict density changes post-operatively. The common cemented designs (cylindrical, slightly conical) had strain shielding in the superior femoral head (>35% reduction) as well as strain concentrations (strain>5%) in the neck regions near the implant rim. The cortex-preserving (spherical) and strongly conical designs showed less strain shielding. In contrast to the cemented implants, line to line implants showed a density decrease at the centre of the femoral head, while all press-fit versions showed a density increase (>100%) relative to the native femur, which suggests that uncemented press-fit implants could limit bone resorption.     

Numerical simulation of load-induced bone structural remodelling using stress-limit criterion

A simple and efficient numerical method for predicting the remodelling of adaptive materials and structures under applied loading was presented and implemented within a finite element framework. The model uses the trajectorial architecture theory of optimisation to predict the remodelling of material microstructure and structural organisation under mechanical loading. We used the proposed model to calculate the density distribution of proximal femur in the frontal plane. The loading considered was the hip joint contact forces and muscular forces at the attachment sites of the muscles to the bone. These forces were estimated from a separate finite element calculation using a heterogeneous three-dimensional model of the proximal femur. The density distributions obtained by this procedure has a qualitative similarity with in vivo observations. Solutions displayed the characteristic high-density channels that are evident in the Dual X-ray Absorptiometry scan. There is also evidence of the intramedullary canal, as well as low-density regions in the femoral neck. Several parametric studies were carried out to highlight the advantages of the proposed method, which includes fast convergence and low-computational cost. The potential applications of the proposed method in predicting bone structural remodelling in cancer are also briefly discussed.     

Activity intensity,assistive devices and joint replacement influence predicted remodelling in the proximal femur

Bone morphology and density changes are commonly observed following joint replacement, may contribute to the risks of implant loosening and periprosthetic fracture and reduce the available bone stock for revision surgery. This study was presented in the ‘Bone and Cartilage Mechanobiology across the scales’ WCCM symposium to review the development of remodelling prediction methods and to demonstrate simulation of adaptive bone remodelling around hip replacement femoral components, incorporating intrinsic (prosthesis) and extrinsic (activity and loading) factors. An iterative bone remodelling process was applied to finite element models of a femur implanted with a cementless total hip replacement (THR) and a hip resurfacing implant. Previously developed for a cemented THR implant, this modified process enabled the influence of pre- to post-operative changes in patient activity and joint loading to be evaluated. A control algorithm used identical pre- and post-operative conditions, and the predicted extents and temporal trends of remodelling were measured by generating virtual X-rays and DXA scans. The modified process improved qualitative and quantitative remodelling predictions for both the cementless THR and resurfacing implants, but demonstrated the sensitivity to DXA scan region definition and appropriate implant–bone position and sizing. Predicted remodelling in the intact femur in response to changed activity and loading demonstrated that in this simplified model, although the influence of the extrinsic effects were important, the mechanics of implantation were dominant. This study supports the application of predictive bone remodelling as one element in the range of physical and computational studies, which should be conducted in the preclinical evaluation of new prostheses.     

顺行髓内钉、逆行髓内钉及锁定加压钢板内固定治疗股骨远端骨折的对比研究

摘要目的：探讨顺行髓内钉、逆行髓内钉及锁定加压钢板内固定3种方法治疗股骨远端骨折患者的疗效。方法：对2011年1月至2012年12月间我院收治的101例股骨远端骨折进行临床随机分组手术,分别在手术中使用顺行髓内钉、逆行髓内钉以及锁定加压钢板内固定。对三组患者手术时间、术中出血量以及切口长度等一般情况进行比较分析,同时采用Harris评分系统对三组患者术后恢复情况进行分析比较。结果：经过手术治疗后,逆行髓内钉组Harris评分显著高于其他两组（P〈0．05）。另外,逆行髓内钉组手术过程短、出血量少、手术切口小,上述指标与其他两组比较均有统计学意义（P〈0．05）。结论：股骨远端骨折行逆行髓内钉治疗的疗效优于顺行髓内钉以及锁定加压钢板内固定,具有手术时间短、术中出血少、切口小等优点,能够有效提高术后膝关节功能的恢复,值得临床推广使用。