单髁膝关节置换术后膝关节三维运动学特性研究

目的探讨单髁膝关节置换后膝关节与骨关节炎病变膝关节及正常膝关节在正常平地行走中的三维运动学差异。方法在瑞金医院骨科2011年3月至2012年5月间进行的7例单髁膝关节置换手术病例和10位健康人对照组进行步态分析比较。7例单髁病例中,男1例,女6例,平均年龄65．3岁（53～73岁）,步态分析时间距手术后平均7个月（4～12个月）,所有单髁膝关节置换均使用Oxford（BiometLtd）活动平台内侧单髁膝关节假体,手术病例对侧膝关节也存在内侧间隙骨关节炎并等待进行手术。10例健康人中,男5例,女5例,平均年龄56．8岁（53～6l岁）,所有健康人对照组均无髋膝关节疼痛和髋膝关节活动功能障碍病史。本研究采用红外运动捕捉系统（MX．F40,Vicon,OxfordUK）,对多点体表标记点进行步态数据记录,计算股骨相对于胫骨的旋转和移动运动学数据,比较单髁膝关节置换后膝关节在上述三维运动中与对侧病变膝关节和正常膝关节的差异。结果在步态周期内,单髁膝关节置换术后膝关节三维运动学表现与对侧病变膝关节及正常对照组膝关节均存在不同的差异。其中,在矢状面屈伸运动、水平面的内外旋运动、冠状面内外翻运动以及前后方向平移运动中,单髁置换后膝关节运动曲线都与正常膝关节更为接近。结论单髁膝关节置换术后,膝关节运动学表现上比对侧病变膝关节在旋转运动和平移运动中,更接近与正常膝关节的运动学特性。     

后稳定型膝关节置换术胫骨平台假体后倾角对膝关节运动学、股四头肌肌力以及髌股关节接触应力的影响

<正>作者采用膝关节模型研究后稳定型膝关节置换术胫骨平台假体后倾角对膝关节运动学、股四头肌肌力以及髌股关节接触应力的影响,发现随着胫骨平台假体后倾角的增加,股四头肌肌力以及髌股关节接触应力均减小。在胫骨平台假体后倾角为5°和10°时分别发现胫骨组件前移和胫骨组件前方撞击。增加胫骨平台假体后倾角可以增加运动效果,但是会增加关节不稳定。因此,作者建     

活体人工髋关节假体植入位置的有限元分析

目的建立人工髋关节置换术后的三维有限元模型,分析假体和股骨的力学分布,为研究活体内假体及评估手术实施情况提供新的方法。方法选择1例生物型人工髋关节假体置换后志愿者,64排CT扫描髋关节,通过三维建模软件建立三维有限元模型,模拟单肢负重站立状态下的受力,分析假体和股骨的应力分布;实际植入位置为实验组,对假体植入的角度进行-10°、-5°、+5°、+10°的模拟作为对照组,研究相应位置的应力变化情况,并与实际手术情况进行对比。结果患者人工股骨头假体置换术后CT扫描图像建立的三维有限元模型,经受力比较发现并非为最佳植入位置。结论活体人工髋关节模型的应力分布是假体置换后的应力传导真实反映。人工髋关节活体建模可以对手术结果进行更为合理、可靠的分析。     

失稳膝关节初次人工关节置换假体选择与手术技巧

目的探讨失稳膝关节初次行人工关节置换的手术技术、假体选择和临床疗效。方法回顾性研究使用特殊膝关节假体进行初次全膝关节置换术治疗失稳膝关节共24例(37膝)。结果术后平均随访30.8个月。HSS评分从术前平均43.8分增加到术后平均90分。膝关节活动范围从术前平均85.0°增加到术后平均114.2°。术后X线复查测量股胫角为5.4°(5～7°),无假体松动。结论对于失稳的膝关节初次行人工全膝关节置换手术,注意适应证的选择,掌握良好的软组织平衡技术,选择髁限制假体、加长柄假体、旋转铰链式假体等特殊假体,可以获得满意效果。     

国产TC-Dynamic假体全膝关节表面置换的近期疗效

目的评价应用国产后稳定型TC-Dynamic假体行人工膝关节表面置换的临床近期疗效。方法应用国产TCDynamic假体行全膝关节表面置换28例(31膝)。结果患者均获5～17个月随访,按1989年美国膝关节外科学会评分系统评分,膝关节评分平均为83分(术前平均为39分);功能评分平均为85分(术前平均为36分)。结论国产TCDynamic假体设计合理、操作便利、患者功能康复可靠,适宜推广。     

Genesis Ⅱ与PFC两种假体全膝关节置换术后膝前痛的比较研究

目的 探讨全膝关节置换术后膝前痛与髌骨置换及假体设计的关系,GenesisⅡ与PFC两种股骨假体与髌骨之间的友好性.方法 回顾性分析由同一组高年资医生施行初次全膝关节置换术的145例(145膝)骨关节炎患者的临床资料.均采用后十字韧带替代型全膝关节假体,髌骨置换74例,其中32例使用GenesisⅡ假体、42例使用PFC假体;髌骨未置换71例,其中38例使用GenesisⅡ假体、33例使用PFC假体.术后评估美国特种外科医院(Hospital for Special Surgery,HSS)膝关节评分、髌骨评分、髌骨功能评分、膝关节活动度、膝前痛评分、满意度和X线片上髌骨倾斜和半脱位情况.结果 随访144例,随访时间21～43个月,平均33个月.术后膝前痛发生率:髌骨置换组与未置换组的差异无统计学意义,组内使用GenesisⅡ假体与PFC假体的差异有统计学意义.使用PFC假体者4例再次手术.功能评分:髌骨置换组及髌骨未置换组中使用GenesisⅡ假体与PFC假体术后HSS评分、活动度、满意度的差异均无统计学意义,而术后髌骨评分及髌骨功能评分的差异有统计学意义.结论 术后膝前痛的发生率与是否置换髌骨无关,而与假体设计有关;GenesisⅡ假体与髌骨的关系更加友好.     

应用内轴膝人工膝关节置换的进展

人工膝关节置换(TKA)是治疗膝关节骨关节炎的重要手段。然而置换后的膝关节运动学不同于自然膝关节运动学,常出现反向前移,是影响患者满意度提高的重要原因。内轴膝关节假体在设计上能更好地模拟自然膝关节的运动,为TKA假体提供了较好的选择。本文对内轴膝关节的基本特点和临床应用效果及进展作一综述。     

计算机辅助外科(CAS)施行传统性全膝关节置换器械的新技术

[目的]研究应用计算机辅助外科(computer aided surgery,CAS)施行传统性全膝关节置换器械的新技术.[方法] 30例膝关节内翻畸形患者,由同一化医师施行传统性全膝关节置换术,术后全部患者行患肢直立位冠状面X线摄影,选其中20例作为研究对象,评估移植假体位置的正确性程度.[结果] 20例患者行X线分析研究,以下列不同角度进行测定,结果分析使用SPSS版本19.冠状轴线:股骨部假体位置沿股骨机械轴线,均值为:2.5°内翻～4.4°外翻(SD 0.33);股骨部假体位置为:2.5°内翻～1.7°外翻(SD 0.23);总的股胫机械轴线角度为:3.2°内翻～4.5°外翻(SD 0.40).假体组成部分超出±3°内翻/外翻者,胫骨0例,股骨1例.股骨与胫骨机械性轴线超过3°内翻/外翻为3例.以上数据表明膝关节外科能全面取得韧带的平衡.矢状轴线:研究假体置换的矢状轴线最佳位置,尚存在争议.故未作分析.[结论] CAS适用于传统性全膝关节置换术,既不增加患者痛苦,还能进一步完善外科手术技术,使假体移植达到正确位置.     

不置换髌骨膝关节置换术后髌骨不稳的原因及预防

目的 探讨全膝关节置换术后髌骨不稳的原因和预防措施.方法 1997年9月至2005年4月对94例(105膝)膝骨关节炎患者行全膝关节置换术.术前膝外翻14例,膝内翻80例,力线正常者11例.所用假体包括可旋转铰链型膝假体RK 10例14膝,活动衬垫型膝假体TACK 40例43膝,GEMINI假体44例48膝,所有患者均不置换髌骨.术前、术后在屈膝30°髌骨轴位片上测量髌骨的排列.结果 术前有膝外翻和髌骨不稳者术后髌骨不稳的发生率分别为28.6%和29.5%,使用RK、TACK、GEMINI假体的患者髌骨不稳的发生率分别为28.6%,20.9%和16.7%.4例有明显股骨或胫骨假体旋转异常.结论 膝关节置换术后出现髌骨不稳定的原因包括患者术前状态、假体设计、假体位置不良等.选择合适的假体,熟练掌握手术技巧,能明显减少膝关节置换术后髌骨轨迹异常.     

锆铌合金膝关节假体在全膝关节置换中的应用

目的探讨锆铌合金膝关节假体应用于全膝关节置换中的临床疗效。方法将锆铌合金膝关节假体应用于26例全膝关节置换术患者。对患者进行影像学和临床评估。结果术后未出现假体金属过敏、深静脉血栓、深部感染病例。患者均获得随访,时间15～58(34. 2±6. 3)个月。随访期间影像学评估:X线片提示下肢力线正常,均未出现吸收性骨反应征及假体松动。临床评估:最大伸膝角度术前为1°～18°(5. 73°±3. 96°),末次随访为-2°～5°(0. 56°±2. 08°);最大屈膝角度术前为61°～106°(83. 23°±19. 71°),末次随访为93°～151°(118. 33°±12. 26°);HSS评分术前为32～45(39. 82±3. 75)分,末次随访为85～99(90. 36±4. 37)分;末次随访膝关节伸屈角度及HSS评分均较术前明显改善(P 0. 001)。结论锆铌合金膝关节假体是全膝关节置换的理想假体,能够有效缓解疼痛和改善膝关节功能,减少假体松动及周围骨吸收,临床和影像学评估证实疗效良好。     

Optimizing flexion after total knee arthroplasty: advances in prosthetic design

The clinical results with most modern total knee arthroplasty (TKA) designs are highly satisfactory regarding pain relief and improving walking ability. However, one problem that has not been addressed fully by most current designs is the ability to consistently achieve flexion greater than 120 degrees. Although the human knee is capable of flexion of more than 150 degrees, an analysis of the results of contemporary TKA reveals that on average, patients rarely flex beyond 120 degrees. Key factors influencing range of flexion after TKA include preoperative knee motion, surgical technique, prosthetic design, and rehabilitation. The success of any total knee system may in part be linked to its ability to optimally restore normal kinematic function. Some arthroplasty designs currently are available that incorporate modifications aimed at improving range of flexion, but limited data currently are available on their function and potential advantages. Currently, an in vitro experimental model incorporating robotics is being used to investigate the kinematics of the native knee and various TKA designs at flexion angles beyond 120 degrees. This robotic model in conjunction with clinical studies may provide an understanding of the limitations of contemporary knee designs regarding achieving higher degrees of knee flexion. This may lead to the refinement of existing designs and development of newer prostheses that may enhance the range of flexion that is achievable after TKA.     

Quadriceps force during knee extension after non-hinged and hinged TKA: an in vitro study

Background and purpose Problems during knee extension, due to kinematic alterations, are not uncommon after total knee arthroplasty. Hinged prostheses provide higher stability than non-hinged designs and may minimize these alterations. Thus, in this in vitro study we investigated the quadriceps force required to extend the knee during an isokinetic extension cycle generating a constant extension moment after non-hinged and hinged total knee arthroplasty.

Methods Human knee specimens were tested in a kinematic knee simulator under physiological conditions, after implantation of two types of non-hinged cruciate retaining prosthesis (Gemini; Link, Germany and Interax I.S.A.; Stryker, Ireland) and a hinged prosthesis (Rotations-Knie; Link, Germany). During simulation of an extension cycle from 120° knee flexion to full extension, the change in quadriceps force to produce the constant extension moment of 31 Nm was dynamically measured using a load cell attached to the quadriceps tendon.

Results After implantation of the non-hinged pros-theses, there was no alteration in maximum quadriceps force in knee flexion compared to physiological conditions, but alteration occurred at lower flexion angle (p=0.002) and increased up to 1,257 (SD 273) N (p=0.04) in knee extension. Following implantation of the hinged prosthesis, there was no alteration in quadriceps extension force in flexion but it decreased to 690 (SD 81) N (p=0.003) in extension.

Interpretation Hinged knee prostheses restore the quadriceps lever arm in knee flexion and improve the lever arm in knee extension due to higher constraint and knee joint stability. This would offer a potential advantage for patients with weak quadriceps strength by making it easier to stabilize the knee in full extension during walking.     

Influences of head/neck ratio and femoral antetorsion on the safe-zone of operative acetabular orientations in total hip arthroplasty

Objective： To study the influences of head/neck ratio and femoral antetorsion on the safe-zone of operative acetabular orientations, which meets the criteria for desired range of motion （ROM） for activities of daily living in total hip arthroplasty （THA）.
Methods： A three-dimensional generic, parametric and kinematic simulation module of THA was developed to analyze the cup safe-zone and the optimum combination of cup and neck antetorsion. A ROM of flexion ≥ 120°, internal rotation ≥ 45° at 90° flexion, extension ≥ 30° and external rotation ≥ 40° was defined as the criteria for desired ROM for activities of daily living. The cup safe-zone was defined as the area that fulfills all the criteria of desired ROM before the neck impinged on the liner of the cup. For a fixed stemneck （CCD）-angle of 130°, theoretical safe-zones fulfilling the desired ROM were investigated at different general headneck ratios （GR=2, 2.17, 2.37, 2.61 and 2.92） and femoral anteversions （FA=0°, 10°, 20° and 30°）.
Results： Large GRs greatly increased the size of safezones and when the CCD-angle was 130°, a GR〉2.37 could further increase the size of safe-zones. There was a complexinterplay between the orientation angles of the femoral and acetabular components. When the CCD-angle was 130°, the optimum relationship between operative acetabular anteversion （OA） and femoral antetorsion （FA） could be estimated by the formula： OA=-0.80×FA＋47.06, and the minimum allowable operative acetabular inclination （OImin） would be more than 2 10.5 ×GR^-2255.
Conclusions： Large GRs greatly increase the size of safe-zones and it is recommended that the GR be more than 2.37 so as to extend the acceptable range of error that surgeons cannot avoid completely during operation. As to the optimum operative acetabular inclination （OI）, surgeons need to make a decision combining with other factors, including stress distribution, soft tissue and cup wear conditions, as well as patients＇ individual situations and demands. The data obtained from this study and the module of THA can be used to assist surgeons to choose and implant appropriate implants.     

In vitro investigation of knee joint kinematics following cruciate retaining versus cruciate sacrificing total knee arthroplasty

The aim of this biomechanical study was to investigate knee joint kinematics following total knee arthroplasty. We compared eight congruent posterior cruciate ligament retaining and four ultracongruent cruciate sacrificing Natural Knee prostheses to the untreated human cadaveric knee joint. A six-degree-of-freedom testing device was used to evaluate knee joint kinematics with a load of 300 Newton and without load application (0 Newton). Statistical analysis was performed using the Wilcoxon rank sum test. A significant increase in antero-posterior translation and tibial rotation was seen in both types of total knee arthroplasty. Implantation of the ultracongruent prosthesis was followed by distinctly more kinematic changes in comparison to the congruent prosthesis. Load application of 300 Newton leads to an anterior dislocation of the femoral component of the ultracongruent prosthesis at 60 degrees of flexion in vitro, indicating an increased demand of compensatory muscular activity in vivo.     

基于CT影像动态膝关节有限元模型的构建及仿真力学分析

目的:基于CT影像资料构建动态性膝关节有限元模型,并进行模型的有效性验证和初步的有限元分析,为膝关节的生物力学研究提供仿真模型和基础数据。方法:选取1名健康男性膝关节CT资料,借助Mimics 19.0和Hypermesh 12.0等软件,从膝关节的三维模型构建入手,经几何重建、逆向工程、网格划分、材料定性等步骤,建立高仿真的有限元模型。通过确定边界条件和扭矩加载产生动态性的屈膝模型,并进行模型的有效性验证。予有限元模型施加近似屈膝活动时所承受的载荷(500 N),研究分析不同屈膝角度下胫股关节和髌股关节的生物力学变化。结果:基于CT影像并结合解剖特性建立了膝关节有限元模型,模型包括骨、韧带、软骨、半月板和髌骨支持带等三维单元,在确立边界条件后施加不同扭矩产生了不同屈膝状态下的有限元模型。根据等同工况(屈膝30°,股四头肌腱受200N牵张)加载显示髌骨的应力峰值为2.209 MPa,平均Mises应力为1.132 MPa;股骨滑车的应力峰值为1.405 MPa,平均Mises应力0.936 MPa,与既往研究比较差异性在1%～13.5%,证明模型的有效性。动态性的模型加载发现:胫股关节的Mises应力随屈膝角度增加而下降;而髌股关节的Mises应力与屈膝角度正相关,不同屈膝角度下各软骨应力面的Mises应力对比,差异均有统计学意义(P0.05)。结论:研究建立的有限元模型结构更趋完整,可有效模拟动态性膝关节的生物力学特性,为膝关节进一步的仿真力学研究提供了支撑。     

In vivo kinematics of high-flex mobile-bearing total knee arthroplasty, with a new post-cam design, in deep knee bending motion

Purpose

The objective of this study was to evaluate the in vivo knee kinematics to assess the available functional motion of the characteristic mobile-bearing prosthesis design and to examine whether the artificial joint would work in vivo according to its design concept.

Methods

We studied 14 knees (11 patients) implanted with the Vanguard RP Hi-Flex prosthesis. This prosthesis has a highly original form of post-cam called a PS saddle design with high compatibility, and with a rotating plate mobile-bearing mechanism. The cylinder-type post-cam is designed to enable contact in early flexion ranges, and to prevent paradoxical anterior femoral component movement. Each patient performed weight-bearing deep knee bending under fluoroscopic surveillance. Motion between each component including the polyethylene insert was analyzed using the 2D/3D registration technique.

Results

The mean range of motion was 122.0°. The mean femoral component rotation for the tibial tray was 5.0°. No paradoxical anterior movement of the nearest point was confirmed between the femoral component and the tibial tray in the early flexion ranges. Initial contact of the post-cam was confirmed at a knee flexion angle of 33.8°. Subsequently, the wide contact of the post-cam was maintained until flexion reached 120° in all knees, but disengagement of the post-cam was observed in two knees when flexion was ≥130°.

Conclusions

The results of this study demonstrated that the prosthesis design generally works in vivo as intended by its design concept. The present kinematic data may provide useful information for improvement of high-flex type prostheses.     

Stress changes of lateral collateral ligament at different knee flexion with or without displaced movements: a 3-dimensional finite element analysis

Objective: To create a 3-dimensional finite element model of knee ligaments and to analyse the stress changes of lateral collateral ligament (LCL) with or without displaced movements at different knee flexion conditions.Methods: A four-major-ligament contained knee specimen from an adult died of skull injury was prepared for CT scanning with the detectable ligament insertion footprints,locations and orientations precisely marked in advance. The CT scanning images were converted to a 3-dimensional model of the knee with the 3-dimensional reconstruction technique and transformed into finite element model by the software of ANSYS. The model was validated using experimental and numerical results obtained by other scientists.The natural stress changes of LCL at five different knee flexion angles (0°, 30°, 60°, 90°, 120°) and under various motions of anterior-posterior tibial translation, tibial varus rotation and internal-external tibial rotation were measured.Results: The maximum stress reached to 87%-113%versus natural stress in varus motion at early 30° of knee flexions. The stress values were smaller than the peak value of natural stress at 0° (knee full extension) when knee bending was over 60° of flexion in anterior-posterior tibial translation and internal-external rotation.Conclusion: LCL is vulnerable to varus motion in almost all knee bending positions and susceptible to anterlor-posterior tibial translation or internal-external rotation at early 30° of knee flexions.     

In Vivo Knee Kinematics: How Important Are the Roles of Femoral Geometry and the Cruciate Ligaments?

BackgroundWhile posterior cruciate-retaining (PCR) implants are a more common total knee arthroplasty (TKA) design, newer bicruciate-retaining (BCR) TKAs are now being considered as an option for many patients, especially those that are younger. While PCR TKAs remove the ACL, the BCR TKA designs keep both cruciate ligaments intact, as it is believed that the resection of the ACL greatly affects the overall kinematic patterns of TKA designs. The objectives of this study are to assess the in vivo kinematics for subjects implanted with either a PCR or BCR TKA and to compare the in vivo kinematic patterns to the normal knee during flexion. These objectives were achieved with an emphasis on understanding the roles of the cruciate ligaments, as well as the role of changes in femoral geometry of nonimplanted anatomical femurs vs implanted subjects having a metal femoral component.MethodsTibiofemoral kinematics of 50 subjects having a PCR (40 subjects) or BCR (10 subjects) TKA were analyzed using fluoroscopy while performing a deep knee bend activity. The kinematics were compared to previously published normal knee data (10 subjects). Kinematics were determined during specific intervals of flexion where the ACL or PCL was most dominant.ResultsIn early flexion, subjects having a BCR TKA experienced more normal-like kinematic patterns, possibly attributed to the ACL. In mid-flexion, both TKA groups exhibited variable kinematic patterns, which could be due to the transitional cruciate ligament function period. In deeper flexion, both TKA functioned more similar to the normal knee, leading to the assumption that the PCL was properly balanced and functioning in the TKA groups. Interestingly, during late flexion (after 90°), the kinematic patterns for all three groups appeared to be statistically similar.ConclusionSubjects having a PCR TKA experienced greater weight-bearing flexion than the BCR TKA group. Subjects having a BCR TKA exhibited a more normal-like kinematic pattern in early and late flexion. The normal knee subjects achieved greater lateral condyle rollback and axial rotation compared to the TKA groups.     

Sagittal flexion of the femoral component affects flexion gap and sizing in total knee arthroplasty

The purpose of this study was to determine how much sagittal rotation of the femoral component affects the flexion gap and femoral component sizing using a computer-simulation technique. The study comprised 25 knees scheduled for total knee arthroplasty (TKA). The femoral component was positioned at -2°, 0°, 2°, 4°, or 6° of flexion to the anterior femoral cortex, and the resected portion of the posterior medial femoral condyle was measured for 3 total knee systems. The amount of the resected bone of the posterior medial condyle decreased approximately 1 mm for every 2° of additional flexion in all TKA systems. Intentional sagittal flexion of the femoral component by several degrees during TKA can be a useful downsizing technique for the femoral component without excessively increasing the flexion gap.     

Hip, knee, and ankle kinematics of high range of motion activities of daily living.

Treatment of joint disease that results in limited flexion is often rejected by patients in non-Western cultures whose activities of daily living require a higher range of motion at the hip, knee, or ankle. However, limited information is available about the joint kinematics required for high range of motion activities, such as squatting, kneeling, and sitting cross-legged, making it difficult to design prosthetic implants that will meet the needs of these populations. Therefore, the objective of this work was to generate three-dimensional kinematics at the hip, knee, and ankle joints of Indian subjects while performing activities of daily living. Thirty healthy Indian subjects (average age: 48.2 +/- 7.6 years) were asked to perform six trials of the following activities: squatting, kneeling, and sitting cross-legged. Floating axis angles were calculated at the joints using the kinematic data collected by an electromagnetic motion tracking device with receivers located on the subject's foot, shank, thigh, and sacrum. A mean maximum flexion of 157 degrees +/- 6 degrees at the knee joint was required for squatting with heels up. Mean maximum hip flexion angles reached up to 95 degrees +/- 27 degrees for squatting with heels flat. The high standard deviation associated with this activity underscored the large range in maximum hip flexion angles required by different subjects. Mean ankle range of flexion reached 58 degrees +/- 14 degrees for the sitting cross-legged activity. The ranges of motion required to perform the activities studied are greater than that provided by most currently available joint prostheses, demonstrating the need for high range of motion implant design.