膝关节松解术后联合骨牵引治疗膝关节僵直

目的总结一种治疗膝关节僵直的新手术方法。方法对48例膝关节僵直患者行手术松解,关节内外和股四头肌成形术后加股骨髁上或髌骨牵引。结果术后对34例患者随访3～36个月,膝关节屈曲角度增加了70°～105°。结论膝关节松解术联合股骨髁上牵引或髌骨牵引手术治疗膝关节僵直能持续延长股四头肌的长度,不断增加关节屈曲角度,有利于术后患者的功能康复。     

跨步或不跨步下的前弓步和侧弓步动作中的髌股关节压力与应力(一)

背景:在髌股关节康复训练中经常进行负重的弓步动作,但这种动作下的髌股关节压力和应力状况尚不明确.方法 :18名受试者在负重下做跨步和不跨步的前弓步和侧弓步动作,负重承量为口J进行12次重复动作的最大负荷.将肌电学、测力平台以及运动学数据输入生物力学模型中,计算不同膝关节屈曲角度下的髌股关节压力和应力.结果 :髌股关节的压力和应力随膝关节屈曲角度增加而增高,随膝关节屈曲角度减小而降低.膝关节屈曲80°～90°时,侧弓步下的髌股关节压力和应力大于前弓步;膝关节屈曲10°～50°时,跨步下的髌股关节压力和应力大于不跨步.弓步和跨步之间无明显的相互作用.膝关节屈曲0°～50°时髌股关节压力和应力小于膝关节屈曲60°～90°时的压力和应力,因此在髌股关节康复训练早期应限制膝关节屈曲在50°以内.解释:为了尽量减小髌股关节的压力和应力,应当在不跨步下进行前弓步和侧弓步练习,尤其是膝关节屈曲0°～50°时.了解不同弓步间髌股关节压力和应力的差异,可能有助于临床医生制定更加安全有效的康复训练方法.     

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。     

髌骨运动轨迹近期研究结果及其主要影响因素分析

髌股关节病变是膝关节前区疼痛的重要原因之一,髌股关节运动轨迹异常是引起髌股关节功能紊乱的主要原因,因此髌股关节运动轨迹一直是研究热点。用于描述髌骨相对于股骨的运动方式主要有外移、外翻以及外旋。从解剖学角度分析,决定髌骨运动轨迹的主要因素有股骨滑车关节面骨性几何学形态、股四头肌以及髌骨内外侧韧带结构,实验研究具体方法也会很大程度上影响最终结果。该文检索主要描述正常髌股关节运动轨迹的研究文献,就具体研究方法及髌骨外移、外翻及外旋运动轨迹进行汇总分析,发现在膝关节屈曲0°～90°范围内,髌骨相对于股骨总体表现为外移、外翻;在0°～30°范围内,髌骨相对于股骨先表现为内移,而后再持续外移。     

克氏针和空心钉张力带内固定治疗横断型髌骨骨折生物力学研究

目的比较空心拉力钉张力带系统和克氏针张力带系统内固定治疗横断型髌骨骨折的生物力学特性。方法对6具新鲜尸体12个下肢标本,开放截骨造成横断型髌骨骨折模型,随机采用空心拉力钉张力带和克氏针张力带固定,在膝关节伸直位加载使髌骨关节面移位达3 mm或最大加载负荷达300 N、周期性牵拉股四头肌腱使膝关节在伸直和屈曲90°之间运动10个周期记录骨折的最大位移以及膝关节固定在屈曲位45°使骨折移位达6 mm的最大载荷进行生物力学测定。结果空心拉力钉张力带组在膝关节伸直位、周期性牵拉股四头肌使膝关节在伸直和屈曲90°之间运动以及屈曲45°时都较克氏针张力带组具有更好的生物力学稳定性。结论空心拉力钉张力带系统较克氏针张力带系统能够提供更稳定的固定效果,为横断型髌骨骨折的一期愈合及患者早期进行功能锻炼以更好地恢复关节功能提供可能。     

基于筋束骨理论铍针松解髌骨外侧支持带改善髌股关节应力集中的有限元分析

目的:在筋束骨理论指导下,基于膝关节有限元模型研究铍针松解髌骨外侧支持带改善髌股关节应力集中的机制,阐释铍针松解术改变髌骨运行轨迹及降低髌股关节压力的生物力学机制。方法:获取1名正常男性(年龄29岁,身高171 cm,体重58 kg)膝关节CT资料,从膝关节的三维有限元模型构建入手,经几何重建、逆向工程、网格划分、材料赋值以及加载分析等步骤,建立筋、骨结构完整的膝关节有限元模型,加载条件设置为膝关节垂直加载500 N负荷,股四头肌腱承受平均值约为200 N的牵张应力,分别在有限元模型屈膝30°位和屈膝90°位状态,模拟铍针松解髌骨外侧支持带,对比研究不同屈膝状态下铍针干预对髌股关节应力集中的改善情况。结果:铍针松解髌骨外侧支持带后髌股关节和胫股关节的应力峰值较干预前均有所下降,分别为:(1)屈膝30°位,髌骨软骨下降0.498 MPa(下降9.06%),股骨滑车下降0.886 MPa(下降16.27%)。(2)屈膝90°位,髌骨软骨下降0.558 MPa(下降8.6%),股骨滑车下降0.607 MPa(下降9.94%)。结论:铍针松解髌骨外侧支持带可有效缓解髌股关节的应力集中并降低局部应力峰值,有利于改善髌骨的运动轨迹并使应力分布更加均匀。     

髌骨交锁一例报告

患者女，28岁。因右膝顶伤后剧痛，膝关节不能屈曲就诊。查体：膝关节前内侧轻度肿胀，压痛（++）。行被动屈伸膝关节运动，剧痛难忍，患者拒绝活动。拟诊为“韧带扭伤”，嘱休息。24h后，膝关节仍处于伸直位，不能屈曲。摄X线片显示右髌骨纵轴线与股骨干纵轴线成45°角，髌骨下极与股骨髁间重叠（图１）。诊断为右髌骨交锁。强行屈膝数次失败后，左手将髌骨上极向股骨后方按压，使髌骨纵轴线与股骨纵轴线平行，右手屈曲膝关节，即听到弹响，髌骨复位，膝关节恢复正常屈伸功能，股四头肌及髌韧带均无损伤，股四头肌肌力5级（图2）。讨论髌…     

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。     

髌骨内推联合股四头肌锻炼可有效改善老年髌股关节炎的症状和功能

目的：观察髌骨内推和股四头肌功能锻炼对老年髌股关节炎患者症状和功能的影响。方法髌股关节炎患者在膝关节伸直状态下,对髌骨进行内推,髌骨活动后,进行股四头肌功能锻炼。对患者治疗前和后的IKDC评分、膝关节非负重状态下的屈曲度进行比较。所有的患者内推前和6个月后进行了膝关节的正侧位片检查。结果2010年10月至2011年12月,符合髌股关节炎诊断的患者168例共203个关节,患者都进行了髌骨内推和股四头肌功能锻炼。所有的患者都得到了最短6个月的随访,平均随访（10±2.5）个月。治疗前、后IKDC评分比较有显著性差异,治疗1月后IKDC评分高于6月后。膝关节非负重状态下屈曲度检查显示治疗前、后比较有显著性差异（ P＜0.05）。 X-ray膝关节侧位片显示Insall-Salvati指数治疗后没有显著改变（ P＞0.05）。结论髌骨内推和股四头肌功能锻炼能够显著改善髌股关节炎的症状和功能。     

空心拉力螺钉张力带联合髌囊环扎治疗髌骨骨折

[目的]探讨空心拉力螺钉张力带固定,联合髌囊环扎治疗髌骨骨折及其疗效.[方法]12例新鲜髌骨骨折,包括8例横行骨折,1例斜行骨折,3例粉碎性骨折.切开复位后以空心拉力螺钉联合聚酯纤维编织缝线"8"字张力带固定,粉碎性骨折加用髌囊环扎,术后早期行被动(CPM)及主动康复训练,以膝关节活动度分级评估治疗效果.[结果]全部病例均获得随访,时间为26～72周,平均35周,切口及骨折均愈合良好,骨折愈合时间8～12周,平均9.7周.采用膝关节活动度评价标准,优膝关节屈伸正常或伸正常屈曲135°～145°,10例;良膝关节伸正常,屈曲120°～134°,2例;可膝关节伸正常,屈曲95°～119°,0例;差膝关节活动范围＜95°,0例.无钉尾剌痛或戳破皮肤,无螺钉松动、断裂等并发症.[结论]空心拉力螺钉对髌骨骨折复位后施加静力加压固定,聚酯纤维编织缝线"8"字张力带固定对抗屈膝过程中股四头肌张力并提供骨折端动力加压作用,两者联合固定是髌骨横行骨折和斜行骨折较理想的治疗方法,不仅具有坚强固定,而且还能提供动静生理应力,防止骨折移位,促进骨折愈合,髌囊环扎术可保证粉碎性骨折的完整性,更有利于上述固定.     

Kinematics of the patellofemoral joint

Summary Patellofemoral kinematics were studied on a computer model. The articulating point of the patella moves from distal to proximal during flexion, until the quadriceps tendon starts to turn around the femur tendofemoral gliding. The pattern of patellofemoral movement consists of a gliding and rolling component, the latter at its maximum at the beginning of flexion. The pathway of the instant centers of motion moves from dorsal to ventral during flexion. Stress analysis shows that the contact area is at all times the area of maximum bending stress. The distal part of the patella is the part with mechanical stress at all angles of flexion. The conclusions to be drawn for treatment are that fractures within the proximal and central part of the patella need a very high stability of internal fixation, the distal part of the patella less so. Postoperative treatment must take into account the changing contact area, because the peak stress is always at the contact area.     

Patellofemoral joint after total knee arthroplasty: Effect on contact area and contact stress

Compressive contact stress between the patella and the anterior femur and between the quadriceps tendon and anterior femur was measured before and after total knee arthroplasty in 5 cadaver knee specimens using a digital electronic sensor. Contact stresses were measured in the normal knee and after total knee arthroplasty with an unresurfaced patella, a dome-shaped patella, and a conforming patella. Patellofemoral contact stresses did not change significantly after total knee arthroplasty when the patella was not resurfaced, but they increased significantly after the patella was resurfaced with both the dome-shaped and the conforming components. The conforming patella had the highest contact stresses because it tilted at flexion angles greater than 90° and applied load to a small area on the superior portion of the patellar component. The conforming patella markedly decreased tendofemoral contact force because the thicker superior pole of the patella tented the quadriceps tendon at flexion angles greater than 120°. This further increased patellofemoral contact force in deep knee flexion.     

Comparison of In Vivo Patellofemoral Kinematics for Subjects Having High-Flexion Total Knee Arthroplasty Implant With Patients Having Normal Knees

This study compares the in vivo patellar kinematics of high-flexion posterior cruciate ligament-retaining and posterior-stabilized total knee arthroplasty (TKA) implants with that of the healthy knee. Twenty-seven subjects performing weight-bearing deep knee bends were analyzed under fluoroscopic surveillance from full extension to maximum flexion. The patellofemoral contact positions and patellar flexion were similar for both TKAs. At low flexion, the patellofemoral contact was significantly more distal on the healthy patella than on the TKA patella, but in deeper flexion, there was no difference among the 3 groups. The tibiopatellar angle was similar for all 3 groups, except at deep flexion where the healthy patella rotated significantly more than the implanted ones. Patellofemoral separation was observed in some TKA knees, whereas it was absent in the healthy knees.     

Physiological sagittal plane patellar kinematics during dynamic deep knee flexion

Purpose

Lateral radiographic views can be easily taken and have reveal considerable information about the patella. The purpose of this study was to obtain sagittal plane patellar kinematics data through the entire range of knee flexion under weight-bearing conditions.

Methods

Patellar flexion angles relative to the femur and tibia and anterior-posterior and proximal-distal translations of the patella relative to the femur and tibia were measured from 0 to 165° knee flexion in nine healthy knees using dynamic radiographic images.

Results

The patella flexed relative to the femur and tibia by two thirds times and one third times the knee flexion angle, respectively. The patella translated in an arc relative to the femur and tibia as the knee flexed. In early flexion, the superior and centroid points translated anteriorly and then the patella translated posteriorly relative to the femur. All three points of the patella translated posteriorly relative to the tibia during a full range of flexion. An average of four and three millimetres proximal patellar translation relative to the tibia was demonstrated from 0 to 20° and 140 to 160° knee flexion, respectively.

Conclusions

Physiological sagittal plane patellar kinematics, including patellar flexion angles and translations relative to the femur and tibia, showed generally similar patterns for each subject. Measurements of dynamic radiographic images under weight-bearing activities may enhance the opportunity to identify patellar pathological conditions.     

Factors affecting range of flexion after total knee arthroplasty

Many factors affect postoperative range of flexion after total knee arthroplasty (TKA). The purpose of this study was to identify the most important factors that affect range of knee flexion after TKA. Sixty-five patients (73 knees) were treated with Genesis II knee replacements. Minimum follow-up was 2 years. Patient demographics (sex, age, body mass index, previous surgery, component type, patella resurfacing, preoperative Knee Society score preoperative range of motion) and radiographic measurements (preoperative tibiofemoral varus/valgus angle, height of the joint line, length of the patellar tendon, shift and tilt angle of the patella) were analyzed statistically. Among these factors, preoperative range of flexion, positively, and preoperative varus/valgus tibiofemoral angle, negatively, affected postoperative range of flexion. The tilt angle of the patella and the tilt angle of the patellar button approached statistical significance in revealing a negative relation with postoperative range of flexion. TKAs in which the patella was not resurfaced tended to lose range of flexion, whereas TKAs in which the patella was resurfaced tended to have no loss of flexion, although the number of TKAs in which the patella was not resurfaced was small. In conclusion, preoperative range of flexion and preoperative varus/valgus tibiofemoral angle affected postoperative range of flexion. The tilt angle of the patella and tilt angle of the patellar button may be factors that affect postoperative range of flexion. Received: September 28, 2000 / Accepted: January 9, 2001     

Patellar tracking during simulated quadriceps contraction

The current study compared patella tracking during simulated concentric and eccentric quadriceps contractions in 12 knees from cadavers using a three-dimensional electromagnetic tracking system. The patella shifted (translated) and tilted medially during approximately the initial 22 degrees tibiofemoral flexion. The patella then shifted and tilted laterally for the remaining arc of tibiofemoral flexion (90 degrees). At 90 degrees tibiofemoral flexion, the patella had an orientation of lateral patella shift and lateral patella tilt. Patella shift was significantly more lateral between 40 degrees and 70 degrees tibiofemoral flexion during concentric quadriceps action than during eccentric contraction. Patella tilt was significantly more lateral between 45 degrees and 55 degrees tibiofemoral flexion during concentric quadriceps contraction than during eccentric action. No other significant differences were seen between the quadriceps contraction conditions. The current study supports the hypothesis that patellar instability is most likely a result of various anatomic and physiologic factors causing a failure of the extensor mechanism to deliver the patella into the femoral sulcus and that a patellar dislocation rarely would occur in a normal knee.     

Association of increased knee flexion and patella clunk syndrome after mini-subvastus total knee arthroplasty

This study reviewed 747 consecutive posterior stabilized total knee arthroplasty (TKA) to explain the increased incidence of patella clunk syndrome that occurred when the surgeon switched from a medial parapatellar arthrotomy to a mini-subvastus (MIS) TKA technique. The incidence of patella clunk syndrome increased with increased postoperative knee flexion. Six weeks after surgery, knees that developed patella clunk had a mean flexion of 124 degrees vs 117 degrees for knees that did not develop this syndrome (P = .016). As the MIS approach resulted in increased knee flexion, this approach was indirectly associated with the increased incidence of patella clunk. Knee flexion at 6 weeks postoperatively was 117 degrees for the MIS knees vs 108 degrees for traditional medial parapatellar arthrotomy knees (P < .001). The effect of increased knee flexion achieved with the MIS approach, which resulted in an increase in patella clunk, was mitigated by using a new posterior stabilized femoral component designed to minimize soft tissue entrapment.     

Q-angle influences tibiofemoral and patellofemoral kinematics.

Numerous surgical procedures have been developed to correct patellar tracking and improve patellofemoral symptoms by altering the Q-angle (the angle between the quadriceps load vector and the patellar tendon load vector). The influence of the Q-angle on knee kinematics has yet to be specifically quantified, however. In vitro knee simulation was performed to relate the Q-angle to tibiofemoral and patellofemoral kinematics. Six cadaver knees were tested by applying simulated hamstrings, quadriceps and hip loads to induce knee flexion. The knees were tested with a normal alignment, after increasing the Q-angle and after decreasing the Q-angle. Increasing the Q-angle significantly shifted the patella laterally from 20 degrees to 60 degrees of knee flexion, tilted the patella medially from 20 degrees to 80 degrees of flexion, and rotated the patella medially from 20 degrees to 50 degrees of flexion. Decreasing the Q-angle significantly tilted the patella laterally at 20 degrees and from 50 degrees to 80 degrees of flexion, rotated the tibia externally from 30 degrees to 60 degrees of flexion, and increased the tibiofemoral varus orientation from 40 degrees to 90 degrees of flexion. The results show that an increase in the Q-angle could lead to lateral patellar dislocation or increased lateral patellofemoral contact pressures. A Q-angle decrease may not shift the patella medially, but could increase the medial tibiofemoral contact pressure by increasing the varus orientation.     

Experimental investigation of the tension band in fractures of the patella

We investigated the strain pattern developed in the anterior and posterior part of the fixed patella during knee motion. Eight fresh cadaver knees were used but two were excluded because of non reliable measurements due to misplacement of gauges. Two strain gauges were bonded in the midline of the anterior and two in the posterior surface of the patella. Threaded steel rods were cemented into the intramedullary femoral and tibial canals. The knee was placed on a special device. The quadriceps tendon was gripped and a 4.5 kg weight was attached to the tibial rod 16.5 cm distal to the joint line. Ten flexion/extension cycles were performed before testing. Initially the intact patella was tested. A transverse osteotomy was performed before being stabilized by the AO recommended tension band technique. The knee was retested again as above. Finally an additional circular wire was passed around the patella and the knee was tested again under the same loading configuration. The intact patella showed weak tensile strain on the anterior and compressive strain on the posterior surface through the range of knee motion. Tension band fixation produced weak tensile strains in the first few degrees of flexion and then weak compressive strains in the posterior surface. The presence of the additional circular wire significantly increased the compressive strain. The classical tension band is highly effective for the fixation of the fractured patella but is improved by an additional circular wire.