股四头肌对髌股关节影响的临床和实验观察

目的 从临床和实验二个方面研究股四头肌对髌股关节运动的影响。方法 对一组２６例５２膝患者进行性ＣＴ检查,了解股四头肌收缩状态对髌股关节排列的影响;对一组标本生物力学实验,用压敏片技术直观地测得股四头肌肌力变化对髌股关节接触压力的影响。结果静力性ＣＴ检查发现在１２膝髌半脱位和１４膝髌骨半脱位和１４膝髌骨外倾,其余病例动力性ＣＴ检查发现在２１膝在股四头肌收缩状态下髌骨半脱位,９例髌骨外倾。力学实验中     

髌股关节排列异常的CT检查

对髌股关节进行ＣＴ测量,确定有无髌股排列异常。方法 对一组２０例４０侧膝关节进行ＣＴ检查,分别在股四头股收缩和松驰状况下扫描,对ＣＴ图像进行测量。结果４０膝中有１０膝为静力性骨外侧半脱位,另３０膝中有１６膝为动力性髌骨半脱位;４０膝中１１膝为性髌骨外倾,另有７膝为动力性髌骨外倾。     

髌股关节异常排列和运动轨迹的动态磁共振研究

目的 观察屈膝过程中健康者及有前膝痛病人的髌股关节的排列和运动轨迹。方法 24个有膝前区疼痛的病人(28膝)参加了本组研究,髌股关节在不同屈曲位置经磁共振成像。5个健康志愿者(10膝)作为对照。测量每一屈曲位置时髌骨运动轨迹及髌股排列情况。同时进行了股四头肌收缩时的动力性检查。结果 28个有症状的髌股关节中有13膝有髌骨外侧半脱位,8膝髌骨外侧倾斜,7膝正常。在股四头肌收缩时的动力性检查时,有髌骨外侧半脱位的病人均有不同程度的半脱位加重。没有半脱位的15膝中有4膝出现了半脱位,5例髌骨倾斜,2例半脱位并倾斜。结论 屈膝前30°范围内的股四头肌收缩时的动态磁共振能提高髌股关节异常的检查准确性。     

髌股关节紊乱症的关节镜诊断和治疗

目的:对一组髌股关节紊乱症从关节镜下观察髌骨运动轨迹及关节软骨损伤情况并予治疗。方法:对临床诊断为髌股关节紊乱症的30例38膝,其中20例27膝经CT检查明确髌股关节排列异常的类型和程度,所有38膝均经关节镜关节腔内行外侧支持带松解术。结果:术后随访平均131个月,优良率为737%。经CT检查的27膝关节镜下所见均有软骨损伤,在较严重软骨损伤(OuterbridgeⅢ期Ⅳ期)的21膝中,CT测量显示有静力性髌股排列异常者占15膝(71%)。结论:髌股关节紊乱症的外侧髌股关节有着较高而持续的接触压力,对软骨危害较大。通过关节镜进行诊断和治疗,具有创伤小、诊断明确、早期活动、恢复快等优点,且不妨碍以后必要的进一步手术。术后坚持股四头肌肌力锻炼,维持股四头肌(尤其是股内侧肌)的力量,是获得持久良好疗效的保证。     

髌股关节不稳定症的影像学诊断与治疗

髌股关节是伸膝装置中的重要组成部分，髌骨在股骨滑车凹中正常运动轨迹依赖于髌骨与股骨髁间凹的骨性关节和关节囊、支持带提供的静态稳定作用，以及股四头肌的动态稳定作用。如果髌股关节不稳定，就会发生髌股关节运动轨迹的改变、髌骨向外侧倾斜和／或半脱位，使外侧髌股关节面产生过高压力，软骨被磨损，最终导致软骨软化和骨关节炎。     

屈膝30°体位CT扫描对青少年习惯性髌骨脱位的诊断价值

目的分析屈膝30°体位CT扫描对青少年习惯性髌骨脱位的诊断价值。方法观察组收集临床症状符合及关节镜手术确诊,且年龄14~18岁的39例(50膝)青少年习惯性髌骨脱位的CT扫描资料。对照组收集同年龄段25例(50膝)正常膝关节的CT扫描资料。2组均取仰卧位、屈膝30°行CT扫描。结果观察组和谐角明显小于对照组,外侧髌骨角明显大于对照组,差异有统计学意义(P0.05);但2组髁间沟角差异无统计学意义(P0.05)。观察组中CT扫描诊断脱位48膝,未脱位2膝;对照组中CT扫描诊断脱位1膝,未脱位49膝;敏感性为96%,特异性为98%。结论屈膝30°体位CT扫描应用于髌股关节不稳的检查,可以更好地显示髌股关节的对合情况,放射科医师单纯从CT扫描征象中即可达到很高的诊断效能,如果结合病史及临床检查,诊断青少年习惯性髌骨脱位准确、有效。     

应用缝匠肌治疗伸膝功能障碍

目的 应用缝匠肌前移治疗髌骨向外移位和加强伸膝力量。方法 游离缝匠肌下１／３段、下２／３段,其止点不切断,移至髌骨前固定。结果 治疗髌骨软化症８例１０膝,随访７例８膝,髌股关节痛消失;髌骨半脱位７例９膝,随访６例７膝,髌骨无再半脱位;复发性髌骨脱位１５例１８膝,随访１２例１３膝,髂骨无再脱位;股四头肌瘫痪５３例,随访３４例,伸膝平均肌力由术前０．８９级,增至２．７６级;膝关节伸直型僵硬１２例,随访     

髌骨稳定性的解剖学与生物力学研究进展

正常髌股关节的骨性结构(关节形态和下肢力线)和软组织结构(静力装置和动力装置)组成髌股关节的解剖结构,有利于维持髌骨的稳定性.股骨滑车凹软骨的深度及两侧滑坡的坡度在抑制非平衡力诱发髌骨半脱位或脱位时扮演着重要角色,Q角偏大时增大髌骨的外向牵拉力.膝关节屈曲O.～20.时内侧髌股韧带在阻止髌骨脱位的软组织中发挥50%～60%的作用,股内侧斜肌纤维不是经由股四头肌腱而是直接附着于髌骨内侧缘.并独立于其他肌肉.由独立的神经支配.股内侧斜肌完全松解后,髌骨稳定性将降低30%.髌股关节的解剖出现异常.可直接导致髌骨不稳定.或成为其他不稳定因素作用的基础.详细了解髌股关节的解剖学与生物力学.时髌骨不稳定的诊断及治疗方案的选择有重要的指导意义.     

早、晚期髌股关节炎手术治疗方法的改进

目的　改良早、晚期髌股关节炎的手术治疗方法 ,提高治疗效果。　方法　①游离缝匠肌下 1/3段 ,止点不切断移至髌骨前 ,建立髌骨向内可变拉应力 ,治疗髌骨向外移位引起的早期髌股关节炎。②游离缝匠肌中下 2 /3段 ,止点不切断移至膝前 ,加强股四头肌肌力 ,治疗晚期髌股关节炎髌骨切除后伸膝肌力减弱。　结果　治疗早期髌股关节炎 8例 10膝 ,随访 7例 8膝 ,临床症状消失 ,关节伸屈活动正常 ;治疗晚期髌股关节炎髌骨切除后肌力减低 7例 8膝 ,髌骨切除同时缝匠肌前移 3例 3膝 ,术后伸膝肌力Ⅳ～Ⅳ 级 ,很好完成最后的 10°～ 15°伸膝。　结论　方法新颖、操作简单、效果确实、值得推广     

改良髌骨半脱位的治疗方法

髌骨半脱位,临床上较常见,治疗方法较多,效果不尽人意。１９７８年始应用带状缝匠肌,游离下１／３段,其止点不切断,移至髌骨前固定,增建一个动力性髌韧带和增加股内侧肌肌力,加强髌骨向内的可变拉应力,使Ｑ角变小,恢复髌骨的动力性稳定,防止髌骨半脱位,收到满...     

A modified system of stress radiography for patellofemoral instability

Axial radiographs were obtained under valgus and external rotation stress at 45 degrees of knee flexion with and without contraction of the quadriceps muscle in order to assess the dynamics of patellar subluxation or dislocation. The radiography was performed on 82 knees in 61 patients with patellofemoral instability, and on 44 normal knees. The lateral patellofemoral angle and the congruence angle were measured and compared with the conventional Merchant views. Both parameters showed greater differences between symptomatic and normal knees on the stress radiographs obtained without quadriceps contraction. There was a major difference in the lateral patellofemoral angles between the groups, which clearly distinguished symptomatic knees from normal controls. Congruence angles on stress radiography had a significant correlation with the functional scores obtained after a period of conservative treatment and a positive correlation with the frequency of patellar subluxation. When the quadriceps contracted, two patterns of patellar shift were observed. While the patella reduced into the trochlear groove in all normal knees and about 70% of the symptomatic knees, contraction of the quadriceps caused further subluxation of the patella in the remaining symptomatic knees. All the knee joints which showed this displacement failed to respond to conservative treatment and eventually required surgical treatment. Thus, this technique of stress radiography is a simple, cost-effective and useful method of evaluating patellar instability and predicting the prognosis.     

Axial computed tomography of the patellofemoral joint with and without quadriceps contraction

Computed tomography was used to analyze the patellofemoral relationship during the first 60° of knee flexion in patients with chronic patellofemoral pain syndrome (49 knees) and a healthy control group (15 knees). The patellofemoral joints were imaged axially through the center of the patella articular cartilage with the knee flexed 0°, 0° with maximal quadriceps muscle contraction, 30°, and 60°. In 0° of knee flexion, the sulcus angle was greater in the symptomatic group than in normal controls. The patella displaced further laterally, and the lateral patellar tilt was greater. The patellar lateral index was found to be greater at 0° and indicated severe abnormality with full quadriceps muscle contraction. The Laurin angle was pathologic with increased medial opening, especially with muscle contraction. At 30° of knee flexion, these differences were less marked than at 0°. No relevant differences were found with 60° of knee flexion. This study showed that the sulcus angle, lateral patellar displacement, lateral patellar tilt, patella lateral condyle index, and Laurin angle are relevant diagnostic features in 0° of knee flexion, indicating a pathological femoral patellar gliding mechanism. Our evaluation also demonstrated the influence of full quadriceps muscle contraction, especially regarding lateral patellar displacement and the Laurin angle, and it was most prominent on the patella lateral condyle index. Thus, quadriceps muscle contraction often creates a more pathological displacement of the patella, which can be depicted using axial computed tomography.     

Reproducibility of patellofemoral CT scan measurements

At least seven parameters have been described for the measurement of patellofemoral malalignment on CT scanning; three of which measure lateral patellar tilt, two lateral patellar shift and two femoral trochlear dysplasia. We studied 22 knees in 18 patients complaining of patellofemoral pain in order to investigate the reproducibility of these methods. CT scans of the patellofemoral joint were performed in each knee at 0 degrees and 20 degrees of flexion. The seven parameters were recorded from each scan by three independent observers in a blind study. The reproducibility was studied by means of the intraclass correlation coefficient (ICC). Parameters measuring lateral patellar tilt showed excellent reliability (ICC>75%). The measurements of lateral patellar shift and femoral trochlear dysplasia showed a fair or poor correlation (ICC<75%). We suggest that parameters for measuring lateral patellar tilt only should be used from CT scanning when planning treatment for patello-femoral malalignment.     

Patella alta: association with patellofemoral alignment and changes in contact area during weight-bearing

BACKGROUND: Patella alta is a condition which may predispose individuals to patellofemoral joint dysfunction. We compared patellofemoral joint alignment and contact area in subjects who had patella alta with subjects who had normal patellar position, to determine the effect of high vertical patellar positions on knee extensor mechanics. METHODS: Twelve subjects with patella alta and thirteen control subjects participated in the study. Lateral patellar displacement (subluxation), lateral tilt, and patellofemoral joint contact area were quantified from axial magnetic resonance images of the patellofemoral joint acquired at 0 degrees , 20 degrees , 40 degrees , and 60 degrees of knee flexion with the quadriceps contracted. RESULTS: With the knee at 0 degrees of flexion, the subjects with patella alta demonstrated significant differences compared with the control group, with greater lateral displacement (mean [and standard error], 85.4% +/- 3.6% and 71.3% +/- 3.0%, respectively, of patellar width lateral to the deepest point in the trochlear groove; p = 0.007), greater lateral tilt (mean, 21.6 degrees +/- 1.9 degrees and 15.5 degrees +/- 1.8 degrees ; p = 0.028), and less contact area (157.6 +/- 13.7 mm(2) and 198.8 +/- 14.3 mm(2); p = 0.040). Differences in displacement and tilt were not observed at greater knee flexion angles; however, contact area differences were observed at all angles evaluated. When data from both groups were combined, the vertical position of the patella was positively associated with lateral displacement and lateral tilt at 0 degrees of flexion and was negatively associated with contact area at all knee flexion angles. CONCLUSIONS: These data indicate that the vertical position of the patella is an important structural variable that is associated with patellofemoral malalignment and reduced contact area in patients with patella alta.     

Patellofemoral joint contact area is influenced by tibiofemoral rotation alignment in individuals who have patellofemoral pain

STUDY DESIGN: Observational, cohort study. OBJECTIVES: To test the hypothesis that patellar alignment and tibiofemoral rotation alignment explain unique portions of variance in patellofemoral joint contact area in individuals with patellofemoral pain (PFP) and in pain-free control subjects. BACKGROUND: PFP has been proposed to result from increased patellofemoral joint stress due to decreased contact area. Patellar malalignment (lateral displacement and tilt) is believed to be the main contributor to decreased contact area. Recent studies suggest that transverse plane rotation of the femur and/or tibia may also contribute to decreased contact area. METHODS AND MEASURES: Twenty-one subjects with PFP (16 female, 5 male) and 21 pain-free subjects (14 female, 7 male) participated. Subjects underwent magnetic resonance imaging with the knee in full extension and the quadriceps contracted. Measures of patellofemoral joint contact area, lateral patellar displacement, patellar tilt angle, tibiofemoral rotation angle, and patellar width were obtained. Hierarchical multiple regression analyses were performed for each group using contact area as the dependent variable. The order of independent variables was patellar width, patellar tilt angle, and tibiofemoral rotation angle. To avoid multicolinearity, lateral patellar displacement was not included. RESULTS: In the PFP group, patellar width and tibiofemoral rotation angle explained 46% of the variance in contact area. In pain-free subjects, patellar width was the only predictor of contact area, explaining 31% of its variance. Patellar tilt angle did not predict contact area in either group. CONCLUSION: Addressing factors that control tibiofemoral rotation may be indicated to increase contact area and reduce pain in individuals with PFP. Future studies should investigate the contributions of patellar alignment and tibiofemoral rotation to patellofemoral joint contact area at a variety of knee flexion angles.     

Preoperative computed tomography scanning and arthroscopy in predicting outcome after lateral retinacular release.

We initiated a study to look at preoperative, flexed-knee, midpatellar computed tomography (CT) scans and intraoperative arthroscopic findings of lateral patellar articular degeneration in predicting the results after lateral retinacular release for failed nonoperative treatment of anterior knee pain. Twenty patients with 30 painful knees underwent preoperative flexed-knee, midpatellar CT scans that were retrospectively classified by the method of Fulkerson into normal alignment, lateral subluxation, lateral patellar tilt, and combined tilt and subluxation. Arthroscopy was performed before open lateral release. The lateral facet of the patella was graded as either minimal changes (Outerbridge I or II) or advanced (Outerbridge III or IV) changes. Patients were followed for a minimum of 2 years and graded on a standard patellofemoral rating scale. Only 22 of 30 knees that were thought to be clinically malaligned, actually were malaligned by CT scan; eight CT scans were interpreted as normal. The results were further stratified into group A (CT-documented tilt, minimal facet changes), group B (CT-documented tilt, advanced facet changes), and group C (normal CT). Ninety-two percent of group A were rated good or excellent. Twenty-two percent of Group B rated good/excellent, 33% fair, 44% poor. Only 13% of group C rated good (one patient). Based on the results of the study, we recommend lateral release for anterior knee patients with CT-proven patellar tilt who have not responded to conservative treatment and have minimal facet changes with minimal or no subluxation. Lateral retinacular release should not be offered as a treatment to the patient with a normally aligned patella because poor results will most likely result.     

Magnetic resonance imaging of patellofemoral kinematics with weight-bearing

BACKGROUND: Previous studies of the patellofemoral joint have been limited by the use of invasive techniques, measurements under non-weight-bearing conditions, cadaveric specimens, or computerized models. It has been shown that soft tissue and bone can be accurately quantified with magnetic resonance imaging. The present study was designed to define the relationship between the patellofemoral contact area and patellofemoral kinematics in vivo. METHODS: Ten subjects with clinically normal knee joints were scanned with high-resolution magnetic resonance imaging while they pushed a constant weight (133 N) on the foot-plate of a custom-designed load-bearing apparatus. Images were obtained at five positions of flexion between -10 degrees and 60 degrees. Three-dimensional reconstructions were used to measure the patellofemoral cartilage contact area, patellar centroid, patellar medial and inferior translation, patellar medial and inferior tilt, and patellar varus-valgus rotation. All translation and area measurements were normalized on the basis of the interepicondylar distance. Random-effects models of quadratic regressions were used to evaluate the data. RESULTS: The mean contact area ranged from 126 mm(2) in extension to 560 mm(2) at 60 degrees of flexion. The patella translated inferiorly to a maximum distance of 34 mm at 60 degrees of flexion and translated medially to a maximum distance of 3.2 mm at 30 degrees of flexion before returning to nearly 0 mm at 60 degrees of flexion. The patella tilted inferiorly to a mean of nearly 35 degrees at 60 degrees of flexion and medially to a maximum of 4.2 degrees at 30 degrees of flexion. By 60 degrees of flexion, the centroid of the contact area had shifted to an inferior and posterior maximum of 20 and 10 mm, respectively. CONCLUSIONS: We found that lateral patellar subluxation and tilt occurred in these normal knees at full extension and the patella was reduced into the trochlear groove at 30 degrees of flexion. Therefore, we believe that lateral patellar tilt and subluxation observed during arthroscopy of the extended knee may not represent a pathological condition.     

Evaluation of patients with persistent symptoms after lateral retinacular release by kinematic magnetic resonance imaging of the patellofemoral joint

The arthroscopic lateral retinacular release is typically performed to treat patellar pain and instability. This procedure was previously considered to be relatively benign with a low associated complication rate. However, a high incidence of medial subluxation of the patella was recently reported in patients with persistent symptoms after lateral retinacular release. Because the use of physical examination criteria may not always be sufficient to assess patellar alignment, 40 patients (43 knees) were evaluated by the newly developed technique of kinematic magnetic resonance imaging of the patellofemoral joint. One (2%) patellofemoral joint had normal patellar alignment, 10 (23%) had lateral subluxation of the patella, 1 (2%) had excessive lateral pressure syndrome, 27 (63%) had medial subluxation of the patella, and 4 (9%) had lateral-to-medial subluxation of the patella. Seventeen of 40 patients (43%) with unilateral arthroscopic lateral retinacular releases had medially subluxated patellae on the unoperated joints. Because patellar malalignment commonly affects bilateral joints, medial subluxation of the patella may have been present before the lateral retinacular release but was not recognized in these patients.     

Patellar component positioning in total knee arthroplasty

Five human anatomic specimen knees were used to determine the effect of patellar component position on patellofemoral kinematics, contact pressures, and contact areas after total knee arthroplasty using a polyethylene, domed patellar component. Each patellar component was positioned at the anatomic center of the resected patellar surface and then repositioned 5 mm proximally, distally, medially, and laterally. Patellar tilt was greatest with medial positioning of the patellar component and least with central and lateral positioning. At higher knee flexion angles, patellofemoral joint contact pressures increased at the medial facet with the medialized component and at the lateral facet for the lateralized component. The centralized component had the most evenly balanced patellar facet contact pressures. Distally positioned patellar components resulted in decreased patellar component loading at higher knee flexion angles. Central positioning of the patellar component results in optimal patellofemoral mechanics when maximal coverage of the resected patella is desired.