单髁膝关节置换术中假体关节线安装高度误差对衬垫磨损的影响

单髁膝关节置换术（UKA）中的假体安装位置精度是影响术后膝关节临床功能和失效问题的重要因素。然而,UKA假体关节线安装高度误差对胫骨衬垫磨损寿命的影响依然不清楚。本文联合UKA骨肌多体动力学模型、有限元模型和磨损模型,研究了固定式UKA假体7种关节线高度情况对术后衬垫接触力学、累计滑移距离、线性磨损深度和磨损体积的影响。随着UKA关节线高度的升高,膝关节内侧接触力和前后平移运动增大,衬垫的最大范式等效应力与接触应力逐渐增大,衬垫的累计滑移距离增大,最大线性磨损深度与体积磨损量也随之增加,衬垫的磨损部位由衬垫中部区域逐渐向后部偏移。相对于0 mm关节线高度,–2 mm关节线高度时最大线性磨损深度与体积磨损量分别减小了7.9%、6.8%,–6 mm关节线高度时分别减小了23.7%、20.6%,+2 mm关节线高度时最大线性磨损深度与体积磨损量分别增加了10.7%、5.9%,+6 mm关节线高度时分别增加了24.1%、35.7%。UKA假体关节线安装误差会显著影响聚乙烯衬垫关节面的磨损寿命。因此,保守建议临床医生术中UKA关节线高度误差控制在–2～+2 mm之间。     

UKA假体后倾角安装位置对衬垫磨损的影响

目的 研究单髁膝关节置换(unicompartmental knee arthroplasty, UKA)假体不同后倾角度安装对膝关节承载、运动及衬垫磨损的影响。方法 联合UKA骨肌多体动力学模型、有限元模型和磨损模型,分析固定式UKA假体5种后倾角安装位置情况对术后膝关节力和运动、衬垫接触应力、线性磨损深度和体积磨损量的影响。结果 后倾角0°时,衬垫的最大von Mises等效应力为24.84 MPa,接触应力为47.61 MPa, 5百万次循环(million cycle, MC)周期的磨损量为47.29 mm³。随着UKA胫骨假体后倾角的增加,步态周期内旋和后移运动均增大,摆动相的内侧关节力增大,5 MC磨损周期后衬垫von Mises等效应力与接触应力显著减小,衬垫的磨损面积、最大线性磨损深度和体积磨损量随之减少。相对于后倾角0°,后倾角为3°、5°、7°时衬垫的线性磨损深度分别减小了17.8%、19.2%、20.6%;衬垫体积磨损量分别下降了24.5%、30.9%、34.3%。结论 UKA假体考虑后倾角安装超过3°时会显著增加步态周期内旋运动和后移运动,...     

假肢对线对大腿截肢者健侧膝关节内部接触力学特性的影响

目的研究假肢对线对大腿截肢者健侧膝关节内部接触力学特性的影响。方法通过步态实验分析健全人及大腿截肢者在不同对线条件下行走时下肢运动及地面反作用力(ground reaction force,GRF)差异,并利用三维有限元模型分析接受腔内收和外展的异常对线情况对膝关节内部股骨软骨、胫骨软骨与半月板之间接触力学特性的影响。结果健全人在GRF第1峰值时刻膝关节接触力主要集中在内侧,在GRF第2峰值时刻接触力主要集中在外侧,而截肢者接触力在GRF的两个峰值时刻都集中在内侧。接受腔对线内收6°会导致膝关节内侧应力、接触力、接触面积均明显增大。结论截肢者膝骨关节炎发病率高于健全人与其膝关节内侧长期过载有关,接受腔对线内收会增加大腿截肢者健侧膝关节骨关节疾病的风险,临床对线过程中应尽量避免过度内收。     

基于nmsBuilder和OpenSim建立个性化 骨肌模型及其验证

目的 利用nmsBuilder和OpenSim两款软件构建个性化全膝关节置换（total knee replacement, TKR）术后骨骼肌肉多体动力学模型,并用弹跳式和内推式两种步态对构建模型进行验证分析。方法 利用患者骨骼数据,通过nmsBuilder建立骨骼实体、骨标点和肌肉标点,从而自动生成对应参考系统和肌肉,将nmsBuilder生成的骨肌模型导入OpenSim先后执行逆向运动学、静态优化和膝关节接触力分析,最后通过弹跳式和内推式两种步态对模型进行模拟分析,并与实验测量值进行对比验证。结果 除了外侧关节接触力,模型预测的胫股关节接触力幅值和趋势与实验获得数据对比有很好的一致性,构建的骨骼肌肉多体动力学模型可以被用于膝关节研究。结论 利用患者骨骼信息建立的骨肌模型通过输入标记点位置和地面反作用力,可以同时预测出内侧、外侧以及总胫股关节接触力。研究思路可为TKR患者设计个性化膝关节假体提供参考。     

全膝关节置换术后关节线上移对临床功能和运动学参数的影响

目的探讨关节线上移对后稳定假体和后交叉韧带保留假体的全膝关节置换(TKA)患者的临床功能和运动学参数的影响。方法收集北京积水潭院2013年1月至2015年12月使用GⅡ行全膝关节置换术的病例,符合标准的纳入研究,共57膝。按手术假体分为后稳定假体(PS)组和交叉韧带保留假体(CR)组。随访1年,临床功能使用美国膝关节协会(AKS)评分、AKS功能评分和Feller髌骨评分进行评定。用透视技术采集患者的运动学数据,并用2D-3D的注册匹配技术将假体的数字模型还原在影像学动态数据上进行测量。分析患者屈伸活动时股骨内髁、股骨外髁在胫骨平台上的运动,以及股骨胫骨之间的相对旋转。结果 PS组术后的AKS评分(P0. 05)、AKS功能评分(P0. 05)、Feller髌骨评分(P0. 01)和术后活动度(P0. 01)均比CR组好。PS组股骨内髁的移动是(4. 9±3. 0) mm,外髁的移动是(12. 8±3. 3) mm,股胫关节旋转12. 9°±4. 5°; CR组股骨内髁的移动是(4. 3±3. 5) mm,外髁的移动是(7. 9±4. 2) mm,股胫关节旋转6. 7°±5. 9°。PS组更接近生理。结论关节线(JL)上移对CR假体的不良影响比PS假体大,在关节线上移的病例中尽量选择PS假体。     

跳伞着陆过程中膝关节损伤的有限元研究

目的利用膝关节有限元模型和模拟跳伞着陆实验数据,对半蹲式跳伞着陆过程进行数值模拟,并分析膝关节损伤的机理。方法对16名健康志愿者进行半蹲式模拟跳伞实验,跳落高度分别为0.32m,0.52m和0.72m。基于核磁共振成像建立人体膝关节的三维有限元模型,采用实验测得的膝关节运动学和地面反力数据对跳伞着陆过程进行数值模拟。结果关节内组织的应力水平随着跳落高度的增加而增加,外侧半月板和关节软骨承受了较大的载荷,前交叉韧带和内侧副韧带在屈膝角度达到最大时产生明显的应力集中。结论跳伞着陆的高速冲击是造成关节损伤的直接原因,外侧关节软骨和半月板更易受到损伤,前交叉韧带和内侧副韧带较易在屈膝幅度最大时发生撕裂。     

单髁关节置换术与全膝关节置换术治疗膝关节内侧间室骨性关节炎术后运动功能恢复的对照研究

目的 对比单髁关节置换术与全膝关节置换术治疗膝关节内侧间室骨性关节炎患者术后运动功能恢复状态。方法 收集2022年1月至2022年12月在云南省滇南中心医院关节外科治疗的55例膝关节内侧间室骨性关节炎患者的临床资料,根据治疗方式的不同分为全膝关节置换组（TKA组,25例）和单髁关节置换组（UKA组,30例）。对比两组患者术后1、2、3、6个月的爬楼梯测试、起立行走测试、6分钟步行测试的功能恢复情况及膝关节WOMAC评分。结果 所有患者均随访6～9个月,平均（7.15±0.81）个月。UKA组患者比TKA组患者较早地获得更好的WOMAC评分（P<0.05）。UKA组术后1、2、3个月时在爬楼梯、起立行走及6分钟步行测试方面均优于TKA组（P<0.05）,但在术后6个月时两组之间除在爬楼梯测试比较差异有统计学意义（P<0.05）以外,起立行走及6分钟步行测试比较差异无统计学意义（P>0.05）。结论 从治疗膝关节内侧间室骨性关节炎术后早期恢复情况来看,单髁关节置换术较全膝关节置换术能够更快、更好地获得功能恢复。     

基于定量动态负荷下膝关节骨性关节炎软骨MRIT2时间表现研究

目的通过比较膝关节骨性关节炎（OA）病人定量动态负荷前后膝关节软骨T2时间变化情况,分析MRIT2mapping序列反映软骨基质生物力学变化的灵敏度．并验证高磁场条件下人体关节负荷装置的有效性。方法10例膝关节OA病人,其中男性3例．女性7例：年龄4l～66岁．平均年龄57-3岁。依托人体下肢关节力学负荷装置,对其施加膝关节动态负荷。负荷前后行膝关节MRIT2maDping成像,将膝关节轴向负荷区软骨分为4个部位：胫骨平台内、外侧软骨区及股骨内、外侧髁软骨区．分别测量各部位软骨负荷前后的T,时间。对负荷前膝关节内、外侧软骨分级评估进行卡方检验,对同一软骨区动态负荷前后的T2时间进行配对t检验。结果负荷前膝关节内外侧软骨分级差异无统计学意义（P〉0．05）。OA病人负荷前后T2值,胫骨平台内侧软骨区分别为（39．59±4．17）ms、（40．14±4．49）ms（f=0．426,P=0．680）;胫骨平台外侧软骨区（38．85±6．72）ms、（41．25±6．54）ms（t=1．704,P=0．123）：股骨内侧髁软骨区（36．44±5．72）ms、（40．63±4．90）ms（t=1．783,P=0．108）;股骨外侧髁软骨区（39．30±5．78）ms、（46．14±5．03）ms（t=2．826,P=0．020）。结论OA病人负荷后膝关节局部区域软骨区T2时间延长．自行设计的动态加压装置适合在高磁场条件下完成加压及MRI检查,有一定推广意义。     

步态周期下内侧半月板后根部分撕裂对膝关节生物力学的影响

背景：目前针对内侧半月板后根撕裂加速膝关节退变相关生物力学研究大多数仅限于在静态仿真设计的基础上对内侧半月板后根完全撕裂模型进行测试,而对内侧半月板后根部分撕裂在完整步态周期下的生物力学行为尚不清楚。目的：运用动态有限元分析的方法来比较正常膝关节模型与内侧半月板后根部分撕裂模型在完整步态周期下生物力学的差异。方法：以健康成年人右膝关节CT扫描数据为基础,建立包括骨、半月板、关节软骨在内的健康膝关节有限元模型,并在健康模型基础上进一步构建膝关节内侧半月板后根撕裂模型。分别在2种模型上施加ISO标准步态载荷进行仿真测试。比较2种模型对应部件在各时相下应力、位移和接触面积的差异。结果与结论：(1)在完整步态周期下,健康模型内侧半月板后根云图应力分布均匀,而病理模型则在损伤区出现应力集中表现,健康模型最大应力出现在30%时刻外侧半月板内缘,值为29.68 MPa,病理模型最大应力出现在50%时刻外侧半月板内缘,值为30.34 MPa;(2)在完整步态周期下,健康和病理模型胫骨软骨应力分布大体一致,2种模型承受最大应力分别出现在步态周围50%,20%时刻,值大小分别为5.11,6.85MPa;(...     

女性全身关节过度活动患者跳深着陆时膝关节应力分析

目的 分析全身关节过度活动(generalized joint hypermobility, GJH)女性患者与健康女性在跳深着陆中膝关节软骨、半月板von Mises应力分布差异。方法 采集女性GJH患者与女性健康受试者在跳深着陆缓冲阶段垂直地面反作用力(vertical ground reaction force, VGRF)峰值时刻的膝关节运动学与地面反作用力特征,通过逆动力学计算膝关节反作用力,并将膝关节沿股骨长轴方向的合力作为载荷;基于1名女性膝关节三维有限元模型,分别对2组受试者跳深着陆过程进行数值仿真,计算膝关节软骨与半月板von Mises应力及应力分布。结果 在跳深着陆VGRF峰值时刻,GJH组和对照组膝关节屈曲、外翻角度具有统计学意义(P<0.05)。相比于对照组,GJH组膝关节屈曲角度降低、外翻角度增加;在跳深着陆中,GJH组膝关节内部承受应力更大且胫股关节内、外侧室负重区应力分布不均衡,其股骨软骨外侧髁外侧、外侧胫骨软骨前部/中部外侧以及外侧半月板前角、体部外侧缘为应力集中部位。结论 女性GJH患者因膝关节活动范围增大、关节囊松弛,导致在跳跃类项目中膝关节...     

基于MRI的成人正常膝关节软骨形态学测量

目的：了解正常膝关节软骨分布及股骨髁承重区的软骨厚度特点,为膝关节病变早期诊断和动态观察提供依据。方法：选取100名成人志愿者,男、女各50名,年龄20—30岁,平均25．3岁,膝关节均行MRI扫描。应用MIMICS软件对图像进行处理,在矢状位窗面上测量膝关节各部位软骨最大厚度。选择膝关节正常运动时的承重区,测量承重区域软骨的最大厚度并与其他区域进行比较。基于MRI图像行膝关节软骨三维重建,观察膝关节软骨的三维形态特征。结果：膝关节各部位的最大软骨厚度如下。胫骨外侧平台3．19mm,胫骨内侧平台3．07mm,股骨外侧髁2．93mm,股骨内侧髁3．19mm,股骨滑车软骨3．57mm,髌软骨3．75mm。不同性别与左右侧之间的软骨厚度差异无统计学意义（P〉0．05）。胫股关节承重区软骨厚度大于其他区域,有统计学差异（P〈0．05）。结论：成人正常膝关节各区域软骨厚度不同,胫股关节承重区软骨厚度大于非承重区域。基于MRI可以准确地测量膝关节各部软骨的厚度及重建膝关节软骨的三维形态。     

Does joint line elevation after revision knee arthroplasty affect tibio-femoral kinematics,contact pressure or collateral ligament lengths? An in vitro analysis

Introduction

Correct restoration of the joint line is generally considered as crucial when performing total knee arthroplasty (TKA). During revision knee arthroplasty however, elevation of the joint line occurs frequently. The general belief is that this negatively affects the clinical outcome, but the reasons are still not well understood.

Material and methods

In this cadaveric in vitro study the biomechanical consequences of joint line elevation were investigated using a previously validated cadaver model simulating active deep knee squats and passive flexion-extension cycles. Knee specimens were sequentially tested after total knee arthroplasty with joint line restoration and after 4 mm joint line elevation.

Results

The tibia rotated internally with increasing knee flexion during both passive and squatting motion (range: 17° and 7° respectively). Joint line elevation of 4 mm did not make a statistically significant difference. During passive motion, the tibia tended to become slightly more adducted with increasing knee flexion (range: 2°), while it went into slighlty less adduction during squatting (range: –2°). Neither of both trends was influenced by joint line elevation. Also anteroposterior translation of the femoral condyle centres was not affected by joint line elevation, although there was a tendency for a small posterior shift (of about 3 mm) during squatting after joint line elevation. In terms of kinetics, ligaments lengths and length changes, tibiofemoral contact pressures and quadriceps forces all showed the same patterns before and joint line elevation. No statistically significant changes could be detected.

Conclusions

Our study suggests that joint line elevation by 4 mm in revision total knee arthroplasty does not cause significant kinematic and kinetic differences during passive flexion/extension movement and squatting in the tibio-femoral joint, nor does it affect the elongation patterns of collateral ligaments. Therefore, clinical problems after joint line elevation are probably situated in the patello-femoral joint or caused by joint line elevation of more than 4 mm.     

Finite element analysis of unicompartmental knee arthroplasty

Concerns over accelerated damage to the untreated compartment of the knee following unicompartmental knee arthroplasty (UKA), as well as the relatively poor success rates observed for lateral as opposed to the medial arthroplasty, remain issues for attention. Finite element analysis (FEA) was used to assess changes to the kinematics and potential for cartilage damage across the knee joint in response to the implantation of the Oxford Mobile Bearing UKA. FE models of lateral and medial compartment arthroplasty were developed, in addition to a healthy natural knee model, to gauge changes incurred through the arthroplasty. Varus–valgus misalignments were introduced to the femoral components to simulate surgical inaccuracy or over-correction. Boundary conditions from the Stanmore knee simulator during the stance phase of level gait were used. AP translations of the tibia in the medial UKA models were comparable to the behaviour of the natural knee models (±0.6 mm deviation from pre-operative motion). Following lateral UKA, 4.1 mm additional posterior translation of the tibia was recorded than predicted for the natural knee. IE rotations of the medial UKA models were less consistent with the pre-operative knee model than the lateral UKA models (7.7° vs. 3.6° deviation). Varus misalignment of the femoral prosthesis was more influential than valgus for medial UKA kinematics, whereas in lateral UKA, a valgus misalignment of the femoral prosthesis was most influential on the kinematics. Resection of the cartilage in the medial compartment reduced the overall risk of progressive OA in the knee, whereas removing the cartilage from the lateral compartment, and in particular introducing a valgus femoral misalignment, increased the overall risk of progressive OA in the knee. Based on these results, under the conditions tested herein, both medial and lateral UKA can be said to induce kinematics of the knee which could be considered broadly comparable to those of the natural knee, and that even a 10° varus–valgus misalignment of the femoral component may not induce highly irregular kinematics. However, elevated posterior translation of the tibia in lateral UKA and large excursions of the insert may explain the higher incidence of bearing dislocation observed in some clinical studies.     

Unicompartmental knee arthroplasties implanted for osteoarthritis with partial loss of joint space have high re-operation rates

The indications and contraindications for unicompartmental knee arthroplasty (UKA) are controversial. The aim of the study was to determine the risk factors for re-operation in our practice. A series of 113 medial UKAs with mean follow-up of 63 months were reviewed retrospectively. Pre-operatively all knees had radiographic or arthroscopic evidence of severe cartilage damage. The re-operation rate was not related to age, gender, arthroscopic finding or body mass index. It was related to the joint space on pre-operative standing weight bearing radiographs taken in extension. The re-operation rate was 6 (95% CI 2.1–17, P < 0.001) times higher when the thickness of the pre-operative medial joint space was > 2 mm rather than ≤ 2 mm. It was 8 (95% CI 2.8–22.5, P < 0.001) times higher when the thickness of the pre-operative medial space was > 40% of the thickness of the lateral space. The ratio of pre-operative joint spaces has a greater influence on revision rate than the absolute measurement and is independent of radiographic magnification or the patient's normal cartilage thickness. We therefore recommend that, in medial knee osteoarthritis, UKA should only be used if the pre-operative medial joint space on standing radiographs is ≤ 40% of the lateral joint space, even if severe cartilage damage is seen arthroscopically.     

基于CT和MRI膝关节有限元模型建立与不同载荷下生物力学特性分析

基于CT和MRI图像数据建立膝关节有限元模型,采用六面体网格对不同载荷系统下人体膝关节生物力学特性进行研究,并进行有效性验证。建立膝关节有限元模型包括:股骨、胫骨、髌骨、腓骨、股骨软骨、胫骨软骨、腓骨软骨、半月板、前后交叉韧带、内外侧副韧带、髌韧带和股四头肌腱等。对膝关节施加1 kN轴向压缩载荷、134 N后向抽屉力和5、10、15 N[?m内翻力矩和外翻力矩,分析膝关节内软骨和半月板的接触应力和接触面积,股骨内外翻倾角以及位移变化情况。在1 kN压缩载荷和134 N抽屉力作用下,股骨软骨、内外侧半月板和内外侧胫骨软骨的接触应力峰值分别为4.47、3.25、2.83、2.70、2.53 MPa,Von Mises应力峰值分别为2.22、2.44、2.25、2.07、1.64 MPa。股骨相对胫骨前向位移为4.19 mm。施加5、10、15 N[?m内翻和外翻力矩时,股骨内翻和外翻倾角分别为3.49°、4.48°、4.91°和3.22°、3.62°、4.01°。随着力矩的线性增大,膝关节各组成部分的应力呈非线性变化趋势。膝关节软骨、半月板和韧带的研究结果符合其生物力学特性,与前人数值分析和实验研究结果相一致,可为临床膝关节生理病理分析和治疗提供一定的理论依据。     

How critical are the tibiofemoral joint reaction forces during frequent squatting in Asian populations?

This study examines tibiofemoral joint moments and forces when performing a squat. The relevance of studying such an activity is to understand better the mechanical factors involved in the higher incidence of tibiofemoral osteoarthritis in Asian populations where squatting is a common daily activity. In this study, motion analysis data of walking versus squatting were compared, specifically looking at net external knee flexion moments, ground reaction forces and tibiofemoral contact forces. It was found that while squatting resulted in more than 2.5 times larger peak external moments compared with walking, tibiofemoral contact forces were not significantly different. This was due to reduced ground reaction forces recorded for the squatting phase compared to the larger dynamic effects of deceleration at heel strike during walking. The most significant finding of this study was that in squatting, there was a reversal in the tibiofemoral shear reaction force from posterior-directed to anterior-directed, occurring under full compressive load and within a fraction of a second. It is believed that repeated squatting results in many such reversals in shear reactions that may ultimately have significant implications to the long term mechanical function and structural integrity of the joint cartilage.     

全膝关节置换个体化患者右转步态的骨肌多体动力学仿真

目的构建个体化患者全膝关节置换(total knee replacement,TKR)的骨肌多体力学模型,模拟患者下肢右转步态时体内膝关节的生物力学行为。方法以1位具体患者的相关数据为材料,基于骨肌动力学仿真软件Any Body及其依赖于力的运动学建模方法,建立与患者相对应的TKR下肢骨肌多体动力学模型,并对患者的右转步态进行模拟。通过逆动力学分析右转步态,同时预测患者膝关节接触力、关节运动、肌肉活性和韧带力。结果模型预测的胫骨-股骨关节内、外侧接触力的均值均方根误差分别为285、164 N,相关系数分别为0.95和0.61,预测的髌骨接触力均值最大值为250 N。模型预测的接触力和肌肉活性与患者实验测量结果基本一致。此外,模型预测的胫骨-股骨的伸展弯曲、内外旋和内外翻运动的均值分布范围分别为3°~47°、-3.4°~1.5°、0.2°~-1.5°,胫骨-股骨的前后、上下和内外侧平移的运动范围分别为2.6~9.0 mm、1.6~3.2 mm、4.2~5.2 mm。模型还预测了内、外侧旁系韧带力和后交叉韧带力,其最大值分别为190、108、108 N。结论所开发的模型能够预测人工膝关节体内生物力学行为,为后续研究膝关节假体临床失效问题提供强有力的计算平台。     

Finite element analysis of the influence of the posterior tibial slope on mobile-bearing unicompartmental knee arthroplasty

BackgroundThe most common modes of failure reported in unicompartmental knee arthroplasty (UKA) in its first two decades were wear on the polyethylene (PE) insert, component loosening, and progressive osteoarthritis in the other compartment. The rates of implant failure due to poor component positioning in patients who have undergone UKA have been reported. However, the effect of the posterior tibial slope on the biomechanical behavior of mobile-bearing Oxford medial UKA remains unknown.MethodsWe applied finite element (FE) analysis to evaluate the effects of the posterior tibial slope in mobile-bearing UKA on the contact stresses in the superior and inferior surfaces of PE inserts and articular cartilage as well as the forces exerted on the anterior cruciate ligament (ACL). Seven FE models for posterior tibial slopes of −1°, 1°, 3°, 5°, 7°, 9°, and 11° were developed and analyzed under normal-level walking conditions based on this approach.ResultsThe maximum contact stresses on both the superior and inferior surfaces of the PE insert decreased as the posterior tibial slope increased. However, the maximum contact stress on the lateral articular cartilage and the force exerted on the ACL increased as the posterior tibial slope increased.ConclusionsIncreasing the tibial slope led to a reduction in the contact stress on the PE insert. However, a high contact stress on the other compartment and increased ACL force can cause progressive osteoarthritis in the other compartment and failure of the ACL.