胫骨结构抬高术治疗髌股软骨病机理的研究

为客观评价胫骨结节抬高术治疗髌股软骨病的机理,采用Ｆｕｉｊ压敏片测压力和染色法测面积相结合,共测试８具新鲜离体膝关节标本,比较胫骨结节抬高术前后的髌股接触部位、面积和应力分布。发现胫骨结节抬高术后,髌骨的习惯性接触区位置向近端移行,这种现象有助于避开对软骨病灶区的挤压和应力集中,对缓解和消除髌股疼痛症状可能有利。因此,提出了“应力集中传导至软骨损伤区导致髌股疼痛”的设想。胫骨结节抬高术后,小屈膝角度（３０°－６０°）有一定的髌股减压作用,但随屈膝角度增加,髌股接触面积减小并出现压力分布不均或局部高压现象。胫骨结节抬高术后,“腱股接触”现象提早（６０°）出现,对髌股关节生物力学行为可能造成影响。     

股四头肌腱与髌韧带张力关系的生物力学研究

本实验使用扣带式传感器对7例尸体膝关节在生理Q角、Q角增大10°、Q角减小10°和胫骨结节抬高术四种状态下,从90°到0°的伸膝过程中7个屈膝角度时的髌韧带张力和股四头肌腱张力进行测试。不同于传统的观点,我们的实验结果表明:髌骨不是只改变股四头肌腱和髌韧带张力方向的简化滑轮结构。Fp/Fq随膝关节屈曲角度的变化而明显改变,这种比率关系是由髌股关节接触区部位的移行决定的。髌骨不仅按照一定的比率传递股四头肌力,而且还起着增大髌韧带张力伸膝力臂的作用。本文还就Q角改变和胫骨结节抬高术对伸膝装置力学机制的影响进行了探讨。     

胫骨结节抬高内移术的生物力学研究

目的:探讨胫骨结节抬高内移术后膝关节在不同屈曲角度下髌股关节面接触面积和接触压力的变化.方法:选用8具新鲜离体膝关节标本,测量胫骨结节抬高术和胫骨结节抬高内移术前后膝关节Q角角度,并分别采用压敏片和染色法测试两种手术前后髌股关节接触面积、接触部位和应力分布的变化.结果:胫骨结节抬高内移(1.0cm)术后,Q角变小,接触面积减小,接触部位上移,腱股接触提早出现(54.6°),小屈膝角度(30°～60°)时接触压力明显减小,各屈膝角度下外侧关节面的接触压力均向内侧转移.以上变化与胫骨结节抬高术后的变化有明显差异.胫骨结节抬高内移0.5cm时,髌骨接触面积、部位、接触压力变化较小,无明显治疗意义.抬高内移达1.5cm时可造成髌骨内倾斜、髌骨不稳等严重的解剖关系紊乱.结论:胫骨结节抬高内移各1.0cm是较适宜的范围,可矫正髌骨外倾斜,改变髌股习惯接触部位,减轻髌股(尤其外侧关节面)接触压力,重新分布接触压力,腱股接触(55°左右)提早出现.以上变化可矫正髌股关节的解剖紊乱,对临床治疗髌骨软化症有一定意义.     

髌骨倾斜导致髌股关节接触压力与面积改变

我们采用压敏片测量技术对髌骨倾斜状态下髌股关节的生物力学变化特点进行了研究。７例新鲜人尸体标本采用手术方法将髌外侧支持带紧缩造成髌骨外侧倾斜状态，超低压型压敏片置于髌股关节之间，等长加载２００Ｎ，分别在正常状态及髌骨倾斜状态下于屈膝３０°、６０°、９０°、１２０°时测量髌股关节接触压力与面积。结果表明：髌骨倾斜后使髌股关节原正常的“哑铃型”接触压迹转变为“彗星尾状”，外侧面孤立接触，内侧面接触区减少或失接触，接触压力改变表现为髌内侧软骨面接触压力减少或消失，外侧面接触压力集中且明显增高上述改变均以屈膝３０°时最明显。实验结果提示：各种纠正髌骨倾斜状态及治疗髌骨软骨软化症的手术方法，必须以恢复髌骨内外侧关节面压力平衡为标准，特别是屈膝３０°时病理力学的改善最为重要     

股骨髁髌股、胫股关节运动重叠接触区域及其生物力学测定

目的 :明确膝关节运动时胫骨、髌骨与股骨髁接触的重叠区域 ,测量并比较分析重叠区域内髌股、胫股关节各自接触压大小及分布特点 ,探讨髌股关节置换术中股骨滑车假体长度的设计。方法 :收集 8具新鲜膝关节尸体标本 ,在Instron 85 0 1生物力学测试仪上构建实验平台 ,模拟生理状态下膝关节站立到下蹲屈膝的过程 ,采用染色法描记重叠区域、压敏法测量髌股、胫股关节在该区域接触压。结果 :股骨髁关节面存在髌股、胫股关节运动重叠接触区域 ,范围大致相当股骨髁髌股关节接触区域内、始于屈膝 75°髌股接触部的后部分区域 ;重叠区域内髌股、胫股关节各自接触压测定显示 ,前者的接触压明显高于后者。结论 :股骨滑车假体的有效长度应涵盖髌股关节在股骨髁所有接触区域。     

人类髌股关节三维运动规律的研究

本实验通过精密机械式三维位移测量方法，采用１０条新鲜离体人膝关节标本定标加载，分析研究了屈膝过程中的髌股关切运动学及Ｑ角变化对髌股关节运动的影响。结果发现，人类髌股关切具有复杂而有规律性的三维运动特点，对传统认为“髌骨具二维运动”的观点提出了修正。同时发现，Ｑ角异常增大或减小，虽然对髌股运动趋势无显著影响，但可影响髌股运动幅度从而影响髌股稳定性。髌骨的许多特征运动均发生在屈膝３０°之前，髌骨此时也最不稳定，容易受到伤害提示临床手术治疗、护具设计及运动员选材时应予重视。     

髌股关节CT测量参数的比较

目的探讨7个反映髌股关节排列关系参数的叠加法测量和单层法测量可信度.方法 15名前膝疼痛患者的30个膝关节,在屈膝0°和30°股肌松弛状态下,分别用CT图像叠加法和单层法测量髌股关节紊乱的7个参数,测量采用盲法重复,并应用组内相关系数(ICC)评价测量可重复性. 结果在屈膝0°和30°叠加测量法和单层测量法的外侧髌骨角(LPA)、髌骨倾斜角(PTA),以及叠加法的适合角(CA)、股骨滑车角(FTA)具有高可信度(ICC>0.9),单层法的CA在屈膝30°下可信度高(ICC>0.9).结论 CT图像叠加法测量LPA、PTA、CA、FTA有好的可重复性.     

胫骨旋转对髌股关节应力分布的影响

为探明胫骨旋转畸形对髌股关节应力分布的影响,本实验选取7个新鲜离体膝关节,在屈膝30°、60°、90°状态下,分别用压敏片测量胫骨中立位、内旋10°、20°、30°和外旋10°、20°、30°时的内、外侧髌股关节接触压力与峰值。结果显示外旋过程中,外侧髌股关节的接触压均值和接触压峰值呈非线性递增趋势,内侧呈非线性递减趋势;内旋过程中,外侧髌股关节的接触压均值和峰值逐渐减小,内侧则增加显著。上述变化在内旋20°到外旋20°的范围内较有规律。提示胫骨旋转畸形使髌股关节应力分布严重失衡,可能是引起髌股关节退变的重要因素。     

膝关节 Q 角变化规律的实验研究

本研究利用精密三维位移测读仪，研究分析了Ｑ角的变化趋势，以及对髌股关节运动的影响。研究结果表明，Ｑ角是一空间夹角，随屈膝角的增大而增大。力线在平面上的投影所呈的平面夹角Ｑｐ也就是通常所指的Ｑ角，在屈膝１５°左右达最大，而在９０°左右达最小。整个屈膝过程中，ＱＰ在５°－１５°之间变化，变化幅度达１０°左右。     

成年人高位髌骨的X线改变及临床分析

目的观察成年人高位髌骨患者的X线改变,并根据X线改变进行临床分级,以估计预后和指导临床治疗.方法对临床诊断为高位髌骨的18例成年患者,共计34侧膝关节,进行屈膝30°侧位片和髌骨轴位片的拍摄,然后在X片上测定Blumensaat距离、髌骨高度、股骨滑车沟角、髌股协调角、外侧髌股角、髌股指数、髌骨外移度七项参数,并与对照组进行比较.选用Blumensaat距离,髌骨高度及髌股协调角作为临床分级的参数指标.结果病例组与对照组比较Blumensaat距离,髌骨高度的差异有非常显著性意义(P＜0.01);髌股协调角、外侧髌股角、髌股指数、髌骨外移度的差异有显著性意义(P＜0.05);股骨滑车沟角的差异无显著性意义(P＞0.05).临床分级10侧膝关节属轻度,表现为髌骨软骨软化症,药物疗效好;21侧属重度,表现为髌股关节骨关节炎,药物疗效差.结论成年人高位髌骨的X线改变以髌骨的异常高位为主,伴有一定程度的髌骨外移和向外侧倾斜,临床分级在定性诊断的基础上,融入了定量诊断,有进一步研究的必要性.     

Effect of patellar tendon shortening on tracking of the patella

BACKGROUND: Although 10% postoperative patellar tendon shortening after bone-patellar tendon-bone autograft reconstruction of the anterior cruciate ligament has been reported, there are no published studies assessing the effect of shortening on patellofemoral joint biomechanics under physiological loading conditions. PURPOSE: To investigate the influence of patellar tendon shortening on patellofemoral joint biomechanics. STUDY DESIGN: Controlled laboratory study. METHODS: The authors evaluated the patellofemoral contact area, the location of contact, and the patellofemoral joint reaction force and contact stresses in 7 cadaveric knees before and after 10% patellar tendon shortening. Shortening was achieved using a specially designed device. Experimental conditions simulating those occurring during level walking were employed: physiological quadriceps loads and corresponding angles of tibial rotation were applied at 15 degrees , 30 degrees , and 60 degrees flexion of the knee. Patellofemoral joint contact areas were measured before and after shortening using the silicone oil-carbon black powder suspension squeeze technique. RESULTS: After patellar tendon shortening, patellofemoral joint contact areas were displaced proximally on the patellar surface and distally on the femoral surface. Although the contact area increased by 18% at 15 degrees of knee flexion (P = .04), no significant change occurred at 30 degrees or 60 degrees of knee flexion (P > .05). Patellofemoral contact stress remained unchanged after patellar tendon shortening (P > .05) at each flexion angle. CONCLUSION: Our results suggest that a 10% shortening of the patellar tendon does not alter patellar contact stresses during locomotion. It is not clear whether apparent changes in contact location in all positions and contact area at 15 degrees would have clinical consequences.     

髌骨位姿异常对髌股关节接触影响的研究

目的 深入研究髌骨位姿异常对髌股关节的接触影响.方法 通过正常膝关节MRI图像数据建立了髌股关节的正常和异常接触模型,基于正交试验对不同水平的髌股关节异常接触模型进行了有限元仿真模拟.结果 1)在膝关节屈曲过程中,髌股关节接触特性(Von Mises应力、接触压力和接触面积)对髌骨的屈曲和旋转参数最为敏感;2)髌股异常...     

Plain patellofemoral radiographs

Plain radiographs of the patellofemoral joint can show patellar location, bone shape, trabecular pattern, and articular space thickness. With stress application, stability can be measured. Radiographs may be obtained in the lateral, anterior-posterior, oblique or axial projections, with or without weight-bearing, with or without muscle contraction, with or without stress application to the ligaments, and with the knee in varying degrees of flexion. In addition to trabecular pattern, the lateral radiograph can reveal patellar subluxation, height, or trochlear dysplasia. The axial view is rarely useful until 30° of knee flexion and then may show joint space loss, patellar shift or tilt, and trochlear geometry. Stress radiographs may be required to show how far the patella can be displaced from the trochlea with a given force, and thus, it may be the most accurate method of determining patellar instability. Weight-bearing films may be necessary to show loss of joint space.     

The effect of bracing on patella alignment and patellofemoral joint contact area

PURPOSE: To examine the influence of two patellofemoral braces on pain response, patellar alignment, and patellofemoral joint contact area in persons with patellofemoral pain. METHODS: Fifteen women between the ages of 18 and 45 yr with a diagnosis of patellofemoral pain participated. After the assessment of pain response using a visual analog scale, subjects underwent axial plane magnetic resonance imaging of patellofemoral joint at 0 degrees, 20 degrees, 40 degrees, and 60 degrees of knee flexion. Imaging was done with the knee extensors contracted (25% body weight) under three conditions: 1) no brace, 2) On-Track brace, and 3) Patellar Tracking Orthosis (PTO). Measures of mediolateral patellar displacement and tilt and medial and lateral facet contact area were obtained from the magnetic resonance images. RESULTS: On average, the On-Track brace reduced symptoms by 50%, whereas the PTO reduced pain by 44%. When averaged across all knee flexion angles, the PTO and the On-Track brace significantly increased total patellofemoral joint contact area by 52.0 mm (21%) and 59.3 mm (24%), respectively, when compared with the no-brace condition. Bracing had no influence on lateral patellar tilt; however, small but significant changes in lateral patellar displacement were observed. CONCLUSION: Large changes in pain and contact area occurred without sizable changes in patellar alignment. The results of this study suggest that changes in patellar alignment by itself may not be responsible for pain alleviation after patellar bracing.     

The influence of heel height on patellofemoral joint kinetics during walking

Although wearing high-heeled shoes has long been considered a risk factor for the development for patellofemoral pain (PFP) in women, patellofemoral joint kinetics during high-heeled gait has not been examined. The purpose of this study was to determine if heel height increases patellofemoral joint loading during walking. Eleven healthy women (mean age 25.0±3.1 yrs) participated. Lower extremity kinematics and kinetics were obtained under 3 different shoe conditions: low heel (1.27 cm), medium heel (6.35 cm), and high heel (9.53 cm). Patellofemoral joint stress was estimated using a previously described biomechanical model. Model outputs included patellofemoral joint reaction force, patellofemoral joint stress and utilized contact area as a function of the gait cycle. One-way ANOVAs with repeated measures were used to compare the model outputs and knee joint angles among the 3 shoe conditions. Peak patellofemoral joint stress was found to increase significantly (p=0.002) with increasing heel height (low heel: 1.9±0.7 MPa, medium heel: 2.6±1.2 MPa, and high heel: 3.6±1.5 MPa). The increased patellofemoral joint stress was mainly driven by an increase in joint reaction force owing to higher knee extensor moments and knee flexion angles. Our findings support the premise that wearing high-heeled shoes may be a contributing factor with respect to the development of PFP.     

The effects of removal and reconstruction of the anterior cruciate ligament on the contact characteristics of the patellofemoral joint.

Seven cadaveric knees were used to investigate the effects of removal and reconstruction of the anterior cruciate ligament with a bone-patellar tendon-bone graft on contact characteristics of the patellofemoral joint during physiologic levels of quadriceps muscle loads at 30 degrees, 60 degrees, and 90 degrees of knee flexion. Loads were applied to the quadriceps tendon to equilibrate externally applied flexion moments equivalent to one-third of values for maximum isometric extension moments. Patellofemoral contact areas and pressures were measured using pressure-sensitive film. Excision of the anterior cruciate ligament resulted in significant decreases in the total patellofemoral contact area by as much as 94 mm2 (68%), the medial facet contact area by as much as 55 mm2 (93%), the combined average contact pressure by 0.7 MPa (21%), the medial facet average contact pressure by 2.3 MPa (70%), the combined peak contact pressure by 3.0 MPa (38%), and the medial facet peak contact pressure by 5.4 MPa (76%), all at 30 degrees of knee flexion. Excision of the anterior cruciate ligament also resulted in significant decreases in total, medial facet, and lateral facet patellofemoral contact areas at 60 degrees and 90 degrees of knee flexion. Intraarticular reconstruction returned these to levels not significantly different from those of the intact knee.