全膝关节置换术中股骨假体旋转对髌股关节生物力学影响的实验研究

目的探讨全膝置换术中股骨假体的轴向旋转对髌股关节生物力学的影响,为临床指导人工膝关节置换的手术技术提供实验依据,以减少术后髌股关节的并发症。方法取9具正常国人新鲜冷冻尸体的9个膝关节作为研究对象,模拟膝关节自站立位屈膝下蹲的动作,设计制作膝关节实验架,与Instron 8501生物力学测试仪共同搭建实验平台。人工膝关节采用Nexgen LPS全膝系统,手术由同一位有经验的术者实施以控制实验误差,不置换髌骨。比较股骨假体相对于经股骨上髁轴内旋2°、内旋4°、旋转0°(与经股骨上髁轴平行)、外旋2°、外旋4°、平行于Whiteside线等6个不同的轴向旋转位置时的髌股关节的生物力学指标。选择屈膝30°、60°、90°、120°为观察角度,采用日本富士公司生产的压敏片测定髌股接触面积和峰值接触压,最后经扫描和软件处理得到数字化的结果。结果当股骨假体的旋转与经股骨上髁轴平行时,测得的髌股关节峰值接触压结果最优(P< 0．05)。各股骨假体旋转对线组测得的髌股接触面积无显著差异(P>0．05)。但不同标本、不同观察角度下的髌股接触形态不同。结论全膝置换术中股骨假体的轴向旋转对线对于髌股关节的接触压影响较显著,经股骨上髁轴作为股骨假体的旋转对线的参照较为可靠。     

胫骨假体旋转对线技术对髌股关节生物力学影响的实验研究

[目的]探讨全膝置换术中改变胫骨假体的旋转对线技术对髌股关节生物力学的潜在影响,指导术中进行正确的胫股旋转对线,以减少术后髌股关节并发症的发生。[方法]取9个新鲜冷冻人膝关节做实验,自行设计膝关节实验架,与Instron 8501生物力学测试仪共同搭建实验平台,模拟生理状态下膝关节自站立位屈膝下蹲的动作。人工膝关节采用LPS全膝系统,手术由同一位有经验的术者实施以控制实验误差,比较以胫骨结节内、中1/3交界为标志(胫骨结节对线技术)和以股骨假体位置(ROM对线技术)确定胫骨假体旋转的2种技术所获得的髌股关节的生物力学指标,选择30°、60°、90°、120°为实验的观察角度进行各组实验,应用日本富士公司生产的超低敏感型压敏片、低敏感型压敏片测定髌股关节的接触面积和接触压,最后用FPD-305E、FPD-306E压力测定仪和电脑软件处理后得到数字化结果。[结果]人工膝关节置换术中胫骨结节对线技术组与ROM对线技术组所获得的髌股关节的平均峰值接触压、平均接触面积等指标无统计学差异(P>0.10)。[结论]全膝置换术中股骨假体参照经股骨上髁轴确定旋转方位后,采用胫骨结节对线技术抑或ROM对线技术来确定胫骨假体的旋转对线对髌股关节的生物力学未见显著差异。对于旋转限制性较高的假体,ROM技术能够在正确的胫股旋转对线和良好的髌骨轨迹之间作出平衡。     

半月板不同切除术对髌股关节影响的生物力学研究

目的探讨半月板不同部位,不同程度切除后对膝关节髌股关节的影响,为半月板不同切除术的比较提供生物力学依据。方法采用6具人膝关节新鲜标本,保留内、外侧副韧带、关节囊及膝关市伸膝装置,Staubli机器人模拟生理状态下膝关节站立至下蹲屈膝过程,采用超低压型压敏片测量完整膝关节和半月板不同部化及程度切除术后不同屈膝角度下髌股关节接触面积、接触压,并用SPSS 12．0进行双因素方差分析。结果1．无论何种状念的半月板切除,其髌股关节接触的总体趋势没有改变,即膝火节心曲0°～90°髌股关节的接触面积会逐渐增加;2．半月板部分切除与正常膝关节在髌股接触面积、髌股平均接触从压力间的差异无统计学意义;3．外侧半月板全切除与正常膝关节在髌股接触面积之间的差异有统计学意义,其骸股接触面积在各个屈曲角度均小于正常膝关节,其髌股接触平均压力存各个屈曲角度均大于正常膝关节的髌股接触平均压力;4．内侧十月板全切除与正常膝关节在髌股接触面积间的差异无统计学意义,内侧半月板全切其在膝关节屈曲0°～30°之间其髌股关节平均压力均大于正常膝关节髌股关节间平均压力;60°～90°之间与正常膝关节髌股关节间平均压力间的差异无统计学意义。结论外侧半月板全切除术后髌股关节高接触压力、内侧半月板全切除术后髌股关节低接触压力及半月板部分切除术后髌股关节压力分布小均是术后髌股关节炎发生不可忽视的原因。     

股骨远端屈曲角度对人工全膝关节置换股骨假体矢状位力线及功能恢复影响的研究

目的 分析股骨远端屈曲角度对人工全膝关节置换术(total knee arthroplasty,TKA)股骨假体矢状位力线及功能恢复的影响.方法 2007年1月-2009年1月,收治35例35膝股骨远端屈曲角度(distal femoral flexion angle,DFFA)＞6°的患者并行TKA手术,参照Oswa...     

微创膝关节单髁置换术股骨髓内定位与髓外定位假体位置的影像学比较

[目的]通过对膝关节单髁置换术股骨假体的力线测量,评价股骨髓外定位法指导假体放置的有效性.[方法]回顾性分析2007年5月～2010年5月采用微创单髁置换术治疗膝关节内侧间室骨性关节炎的患者73例(80膝),其中股骨髓内定位组(intramedullary alignment guide,IM) 54例(56膝),男23例(23膝),女31例(33膝);股骨髓外定位组(extramedullary alignment guide,EM)19例(24膝),男9例(10膝),女10例(14膝).测量术后即刻股骨假体内翻/外翻和屈/伸力线.[结果]IM组股骨假体内翻/外翻力线为0.59°内翻±3.98°,EM组股骨假体力线平均为0.81°外翻±3.30°,P=0.235 2.IM组股骨假体屈/伸力线为0.70°伸直±3.89°,EM组股骨假体力线为1.12°伸直±3.43°,P=0.564 3.[结论]微创膝关节单髁置换术股骨髓内定位可取得与髓外定位法相同优良的股骨假体力线.     

计算机导航对人工全膝关节置换术下肢旋转对线的影响

目的 对比分析计算机导航人工全膝关节置换术与标准人工全膝关节置换术对假体旋转对线、术后下肢力线、假体位置及功能恢复的影响.方法 将82例患者随机分为两组进行前瞻性对照研究.对照组采用标准全膝关节置换手术,导航组采用计算机导航人工全膝关节置换术.CT测量两组患者术后股骨假体旋转角、胫骨假体旋转角、假体的联合旋转角及假体之间的相对旋转角;X线片上测量两组下肢冠状面力线,假体在冠状位、矢状位的位置.记录术后6周、6个月的膝关节活动范围、KSS评分、Oxford评分及髌股关节评分.结果 对照组和导航组术后股骨假体平均旋转角分别为1.51°±3.55°和-0.63°±3.04°,假体联合旋转角为2.85°±4.07°和0.28°±3.43°,假体之间的相对旋转角为1.44°±4.55°和-0.43°±2.86°,差异均有统计学意义(P＜0.05).两组之间胫骨假体旋转角差异无统计学意义.术后X线片测量结果显示,导航组下肢冠状面力线、股骨假体冠状面位置优于对照组.功能评分显示,术后6周导航组优于对照组,术后6个月两组差异无统计学意义.结论 导航可以避免假体旋转不良,改善下肢旋转对线及冠状面力线,有助于术后早期功能恢复.     

股骨远端旋转力线定位标志研究进展

目的综述人工全膝关节置换术中股骨远端旋转力线定位标志的研究进展。方法广泛查阅近年国内外股骨远端旋转力线相关文献,并对其进行综合分析。结果若假体旋转力线对位不良将导致诸如髌骨脱位、弹响、磨损、髌前疼痛等多种髌股关节并发症。人工全膝关节置换术中确定股骨假体旋转力线的方法较多,常用方法包括股骨上髁轴线、前后轴线、股骨后髁线、屈曲间隙平衡技术、计算机导航技术等。正确选择旋转力线,对减少术后并发症和降低假体翻修率均至关重要。目前人工全膝关节置换术中选择合适的参照轴以保证股骨假体旋转力线对位的准确性仍有争议。结论股骨假体旋转力线是影响人工全膝关节置换术预后极其重要的环节。确定股骨假体旋转力线的方法有待进一步改进。     

全膝关节置换术中髌股轨迹的研究现状

髌股关节并发症是全膝关节置换术后翻修最常见的原因[1],多数表现为髌前痛及髌骨外侧半脱位[2-3],少数表现为髌骨骨折[4]、髌骨撞击综合征[5]、髌骨假体松动等。笔者就全膝关节置换术中髌股轨迹的研究现状综述如下。1解剖与生物力学髌股关节由髌骨关节面与股骨滑车沟及内外侧髁     

髌股关节准动态三维运动模型的构建及其应用

[目的]利用多角度静态核磁共振扫描图像重建在体髌股关节准动态三维运动模型,并以此动态模型计算屈伸膝过程中的髌骨运动轨迹、髌股关节旋转轴。[方法]选择1名健康成年男性,对其右膝关节分别在0°、30°、60°、90°、120°5个屈膝角度进行核磁共振扫描,将扫描结果以Dicom格式导入Mimics软件中,提取髌骨、股骨轮廓,重建五个屈膝角度的静态髌股关节三维模型,再将五个静态模型导入逆向工程软件Rapidform中进行同一坐标系的配准,利用三次样条插值算法,将离散静态模型配准为动态三维运动模型;并据此动态三维模型计算髌骨运动轨迹和髌股关节旋转轴。[结果]基于静态核磁共振图像可以快速构建准确而无辐射的髌股关节准动态三维运动模型,以此动态模型计算出的髌骨运动轨迹和髌股关节旋转轴与既往文献结果相一致。[结论]在屈膝过程中,髌骨随着屈膝角度的增加相对于股骨滑车不断俯屈,同时轻度的外倾和外旋,而髌股关节旋转轴波动在股骨通髁线附近。     

安装大腿近侧气囊止血带对髌股关节运动的影响

目的探讨膝关节屈曲和伸直状态下安装大腿近侧气囊止血带对髌股关节运动的影响。方法收集住院的非髌股关节疾病患者,选择膝关节20侧,在腰麻或连续硬膜外状态下屈膝30°时测量膝关节髌骨高度和股骨滑车角,然后分伸膝位安装止血带和屈膝位安装止血带两组自身先后对比,测量膝关节不同屈曲角度下Laurin髌股关节外侧角和Merchant吻合角。比较气囊止血带在膝关节不同屈伸状态下对髌股关节运动学的影响。结果在膝关节屈曲30°时,髌骨高度的Caton指数为(1.02±0.19),股骨滑车角(138.9±7.4)°。在膝关节屈曲过程中,髌股关节呈现Merchant吻合角增大的趋势,尤其在膝关节屈曲30~45°的时候变化明显,当屈曲角度继续增大时吻合角基本稳定;Lauren髌股关节外侧角保持相对稳定。伸直位和屈曲位安装止血带引起髌股关节Merchant吻合角和Lauren髌股关节外侧角间的差异没有统计学意义。结论在正常膝关节,大腿近侧气囊止血带对髌股轨迹的影响主要表现为最初屈曲的45°内Merchant髌股吻合角的的增大,而Laurin髌股关节外侧较保持相对稳定。伸直位和屈曲位安装大腿近侧气囊止血带对正常膝关节髌股关节运动的改变没有统计学意义。     

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.     

垫片改良设计对膝关节置换术后临床功能和膝关节运动的影响

目的 探讨膝关节假体垫片设计对膝关节置换术后临床功能和膝关节运动学的影响.方法 分析2007年7月至2009年6月使用GENESIS Ⅱ假体行全膝关节置换术的28例膝关节骨关节炎患者的临床资料,共42膝,平均随访27.7个月.按照使用垫片的种类分为高屈曲垫片组(男性1例,女性14例,23膝;年龄54～74岁,平均62.8岁)和标准组(男性1例,女性12例,19膝;年龄54～74岁,平均64.3岁).通过膝关节评分比较两组的临床功能.采用循环透视和软件分析的方法比较两组病例在膝关节屈伸活动时股骨后滚、伸膝装置力臂等参数,评价垫片设计对膝关节运动的影响.结果 标准组和高屈曲垫片组的术后活动度分别为120°和123°,差异无统计学意义.两组在膝关节学会评分上没有差异.高屈曲垫片组术后的Feller评分高于标准组,差异有统计学意义(P=0.012).在影像学测量上,两组病例在0～120°范围活动时股骨后滚和伸膝装置力臂的差异均无统计学意义;活动范围达到130°时,两组的伸膝装置力臂差异有统计学意义(P=0.034).结论 高屈曲垫片的改良设计在减少膝关节置换术后膝前痛的发生、改善膝关节功能方面有一定的作用;但可能会减小伸膝装置的力臂,从而影响股四头肌的做功.     

Influence of prosthetic joint line position on knee kinematics and patellar position

Prosthetic joint line position after total knee arthroplasty (TKA) was investigated using sagittal roentgenograms obtained from six fresh frozen cadaver knees. A specially designed knee testing device was developed that allowed for a controlled flexion angle while maintaining a constant quadriceps force. Pre- and postoperative roentgenograms were obtained from 30 degrees to 120 degrees in 15 degrees intervals. Steinman pins inserted into the medial femoral condyle and patella were used as reference points in the roentgenograms. A displacement vector between the medial femoral condyle and tibial plateau was used to analyze the tibiofemoral joint relationship. The functional patellar length (Insall-Salvati ratio), was used to determine correct patellar height. Another displacement vector was used to measure the patellofemoral joint relationship, and the angle between the patellar cut surface and femoral long axis was also calculated. Bone resection thickness from the femoral, tibial, and patellar surfaces was equal to the prosthetic thickness. This reconstructive scheme produced correct ligament balance and flexibility of the knee without the aid of tensioning devices or special measurements. Patellar tracking appeared to be identical before and after surgery. This accurate but simple surgical technique also reproduced normal knee extensor mechanisms that may influence longevity and long-term results of TKA.     

Effect of total knee arthroplasty on maximal flexion

The advantage of potential flexion offered by total knee arthroplasty (TKA) is limited. In this review of 724 replaced knees, only one-third flexed to 105 degrees, while nearly one-half did not flex beyond 90 degrees. Postoperative flexion depended partly on preoperative flexion and partly on the prosthesis used, but these factors could not be the only determinants of results, for flexion in individual knees could increase, decrease, or remain unchanged whatever the preoperative measurement and whatever the design of prosthesis. Little difference in flexion before or after TKA was found between rheumatoid and osteoarthritic knees. Success or failure of the implant, according to the crude definition used, was not associated with degree of flexion. Patients with the lowest levels of function tended to have TKA with the least flexion and vice versa. Nevertheless, the degree of flexion is only one of the factors influencing mobility.     

Edge loading of patellar components after total knee arthroplasty.

Patellofemoral joint kinematics, contact areas, contact pressures, and contact patterns were assessed after total knee arthroplasty (TKA) using human cadaver knees. Two contemporary TKA systems with anatomic patellofemoral joints were implanted and tested under anatomically based loading conditions. An electromagnetic tracking system was used to evaluate patellofemoral kinematics, and Fuji pressure-sensitive film was used to determine contact areas, pressures, and patterns. Edge loading of patellar components was observed at higher knee flexion angles with both TKA systems. Peak contact pressures seen at the regions of edge loading exceeded the yield strength of ultra-high-molecular weight polyethylene. Efforts to reduce edge loading and contact pressures may decrease the incidence of patellofemoral joint complications and component failure after TKA.     

Contact stresses with an unresurfaced patella in total knee arthroplasty: the effect of femoral component design

Compressive contact stresses between the patella and the anterior femur were measured with a digital electronic sensor before and after total knee arthroplasty (TKA) in 10 cadaver knee specimens. Contact stresses were measured first in normal knees, then after TKA with the Insall-Burstein Total Condylar, Miller Galante II, Ortholoc II, Porous Coated Anatomic, and Profix knee prostheses implanted without resurfacing the patella. The Insall-Burstein, Miller-Galante II, and Ortholoc II prostheses had significantly higher contact stresses than the normal knee throughout the flexion arc. The Porous Coated Anatomic, which has a smooth patellar groove, maintained contact area as in the normal knee and did not have significantly higher contact stresses at flexion angles <90 degrees. At flexion angles > or =105 degrees, patellofemoral contact occurred in two small areas as the patella encountered the intercondylar notch in all components except the Profix. The Profix maintained full contact and low compressive stresses throughout the full flexion arc because of its posteriorly extended patellar groove. Design features of the patellofemoral portion of TKA components are important factors that affect contact stresses in the patellofemoral joint. These features likely will affect the clinical results of TKA with an unresurfaced patella.     

Upsizing the femoral component increases patellofemoral contact force in total knee replacement

In posterior stabilised total knee replacement (TKR) a larger femoral component is sometimes selected to manage the increased flexion gap caused by resection of the posterior cruciate ligament. However, concerns remain regarding the adverse effect of the increased anteroposterior dimensions of the femoral component on the patellofemoral (PF) joint. Meanwhile, the gender-specific femoral component has a narrower and thinner anterior flange and is expected to reduce the PF contact force. PF contact forces were measured at 90°, 120°, 130° and 140° of flexion using the NexGen Legacy Posterior Stabilized (LPS)-Flex Fixed Bearing Knee system using Standard, Upsized and Gender femoral components during TKR. Increasing the size of the femoral component significantly increased mean PF forces at 120°, 130° and 140° of flexion (p = 0.005, p < 0.001 and p < 0.001, respectively). No difference was found in contact force between the Gender and the Standard components. Among the patients who had overhang of the Standard component, mean contact forces with the Gender component were slightly lower than those of the Standard component, but no statistical difference was found at 90°, 120°, 130° or 140° of flexion (p = 0.689, 0.615, 0.253 and 0.248, respectively). Upsized femoral components would increase PF forces in deep knee flexion. Gender-specific implants would not reduce PF forces.