Effects of capsaicin on articular afferents of the cat's knee joint

This study on the effects of capsaicin on primary afferents from normal knee joints of the cat was performed to further elucidate the mechanisms of articular pain evoked by an acute arthritis and by chemical irritants. It showed that close i.a. bolus injection of capsaicin (10^–7–10^–4 M) excites most fine articular afferents (conduction velocity 11.3 m/s) whereas fast units are not excited. Fine afferents with low to medium thresholds to knee joint movement are less readily excited by capsaicin than high threshold ones. The response to capsaicin is usually a rapid burst of impulses of a very short latency. This response pattern differs considerably from that seen after application of endogenous substances produced in inflammation. Thus capsaicin seems to differ in its mode of action from that of endogenous algesic substances.     

关节制动对大鼠膝关节软骨缺损修复的影响

BACKGROUND: Joint immobilization is one of the methods used to treat joint pain and joint injury in the department of orthopedics. Compared with other treatment methods, immobilization can reduce the pain of the damaged synovial joints and avoid the contact stress and friction between the joints. However, immobilization can cause some serious complications such as joint contracture, osteoporosis and cartilage degeneration. OBJECTIVE:To observe the effects of joint immobilization on the repair of cartilage injury of knee joint in rats. METHODS: Osteochondral full-thickness defects (2.5 mm in diameter; 2 mm in depth) were created in the left femoral condyle fossa with a corneal trephine. 36 animals were randomly assigned into immobilization group and control group (n=18 per group). In the control group, animal models were established, without any treatment. In the immobilization group, after model establishment, rats were immobilized by a designed and modified simplified miniature Ilizarov fixator.  RESULTS AND CONCLUSION: (1) Repair rate of cartilage defect: No significant difference in repair rate was detected between immobilization group and control group. (2) Histological staining: Regeneration tissue was mainly fiber cells in both groups. At 8 weeks after surgery, Wakitani score and Mankin score were higher in the immobilization group than in the control group (P < 0.05). (3) Cartilage metabolic marker detection: Compared with the control group, at 8 weeks, C-telopeptide of type II collagen levels in the urine were significantly higher in the immobilization group than in the control group (P < 0.05). (4) Results indicated that persistent immobilization could result in cartilage degeneration, and it was detrimental for cartilage repair. 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

动力型智能假肢膝关节的研究进展

当前和今后一个时期,残疾人对动力型智能假肢膝关节的需求日益迫切。为厘清国内外对动力型智能假肢膝关节的研究进展,本文主要从假肢膝关节的仿生结构和驱动结构设计、控制机制和算法,以及对复杂非结构环境下运动意图识别等方面的研究现状和主要成果进行了归纳总结,并提出动力型智能假肢膝关节在当前研究中面临的问题和挑战,展望了未来的发展方向。     

Effects of posterior condylar offset and posterior tibial slope on mobile-bearing total knee arthroplasty using computational simulation

Background

Postoperative changes of the femoral posterior condylar offset (PCO) and posterior tibial slope (PTS) affect the biomechanics of the knee joint after fixed-bearing total knee arthroplasty (TKA). However, the biomechanics of mobile-bearing is not well known. Therefore, the aim of this study was to investigate whether alterations to the PCO and PTS affect the biomechanics for mobile-bearing TKA.

Influences of the depth-dependent material inhomogeneity of articular cartilage on the fluid pressurization in the human knee

The material properties of articular cartilage are depth-dependent, i.e. they differ in the superficial, middle and deep zones. The role of this depth-dependent material inhomogeneity in the poromechanical response of the knee joint has not been investigated with patient-specific joint modeling. In the present study, the depth-dependent and site-specific material properties were incorporated in an anatomically accurate knee model that consisted of the distal femur, femoral cartilage, menisci, tibial cartilage and proximal tibia. The collagen fibers, proteoglycan matrix and fluid in articular cartilage and menisci were considered as distinct constituents. The fluid pressurization in the knee was determined with finite element analysis. The results demonstrated the influences of the depth-dependent inhomogeneity on the fluid pressurization, compressive stress, first principal stress and strain along the tissue depth. The depth-dependent inhomogeneity enhanced the fluid support to loading in the superficial zone by raising the fluid pressure and lowering the compressive effective stress at the same time. The depth-dependence also reduced the tensile stress and strain at the cartilage–bone interface. The present 3D modeling revealed a complex fluid pressurization and 3D stresses that depended on the mechanical contact and relaxation time, which could not be predicted by existing 2D models from the literature. The greatest fluid pressure was observed in the medial condyle, regardless of the depth-dependent inhomogeneity. The results indicated the roles of the tissue inhomogeneity in reducing deep tissue fractures, protecting the superficial tissue from excessive compressive stress and improving the lubrication in the joint.     

Influences of the temporal nature of the applied load and the tibial baseplate material on the stress distribution in a three-dimensional model of the human knee joint containing a prosthetic replacement

The finite element analysis method was used to determine the stresses in all sections of a three-dimensional model of the proximal section of the human knee joint into which was cemented two parts of a total knee joint replacement (the tibial tray and the tibial baseplate), fully constrained at its distal end, and subjected to a total compressive joint force of 2 kN acting on points corresponding to the condyles. When the mean values of these stresses were computed for all sections of the model, two important trends were seen. First, when the load was applied dynamically, the stresses were between 1 and 20% different than when it acted quasi-statically. Second, regardless of how the load was applied, the stresses when the tibial baseplate was considered fabricated from ultra-high-molecular-weight polyethylene ranged from about 40% lower to about 320% higher compared to when Ti-13Nb-13Zr alloy was used. The significance of these findings as well as the limitations of the study are discussed.     

膝关节关节软骨的三维构建

目的:构建膝关节关节软骨的三维模型,为开展膝关节数字医学研究进行模型构建的探索。方法:人体成年新鲜膝关节标本1例,行CT、MRI扫描,利用三维重建软件Mimics及逆向工程软件Geomagic对图像进行三维重建及图像配准,构建膝关节骨、关节软骨结构。结果:利用Mimics 10.01软件构建关节软骨的三维模型,并形成骨-关节软骨复合模型,导入Geomagic软件中与CT构建的骨三维模型相配准,再次导入CT影像中进行逐层微修饰,验证关节软骨分割效果。最终建立具有骨、关节软骨的三维膝关节模型。结论:三维图像重建技术与图像配准技术可将CT、MRI图像两者结合起来,发挥其各自优势,构建出形态较好的膝关节三维模型。     

假肢膝关节机构的多目标优化设计

背景：如何实现穿戴者的舒适性、运动的灵活性一直是假肢膝关节研究的焦点。 目的：分析膝关节运动过程的瞬心规律,构造合适的评价函数,使其更好地满足穿戴者舒适与自然的要求,进而得到假肢膝关节结构参数。 方法：选取假肢膝关节四连杆机构作为研究对象,建立机构运动学模型,并利用三心定理,推导出连杆瞬心轨迹。考虑穿戴者运动的舒适性,建立了打分系统模型作为评价函数。进一步考虑假肢运动的自然性,以膝盖弯曲过程中实际瞬心与理想瞬心总偏差最小,以及上述的评价函数最大值作为双重优化目标,以假肢膝关节机构仿生学约束、双摇杆机构尺寸约束作为约束条件,建立多目标优化模型。 结果与结论：运用主要目标法,并通过MATLAB编程得到了优化后的假肢膝关节机构的参数。所设计的四杆机构较好地协调了假肢穿戴者的舒适性与运动的自然性。      

Septic arthritis caused by Mycobacterium kansasii in a prosthetic knee joint

Mycobacterium kansasii is a relatively common cause of nontuberculous mycobacterial pulmonary infection. Septic arthritis caused by Mycobacterium kansasii, on the other hand, is rare. Reported here for the first time is the case of an 82-year-old patient with an infection of a prosthetic knee joint with Mycobacterium kansasii.     

The effect of anterior cruciate ligament injury on knee joint function under a simulated muscle load: a three-dimensional computational simulation

Understanding the biomechanical effect of various factors on knee behavior after anterior cruciate ligament (ACL) injury or reconstruction is instrumental for the development of an optimal surgical treatment of ACL injury that can better restore normal knee function. This paper presents the application of a three-dimensional (3D) computational knee model for parametric studies of knee kinematics in response to simulated muscle loads. The knee model was constructed using the magnetic resonance images and biomechanical experimental data of the same cadaveric human knee specimen. The kinematics of the knee predicted by the computational model was compared with that measured from different specimens in a wide range of loading conditions and flexion angles. In general, the model predictions were within the range of experimental data. The model was then used to predict knee motion, ligament forces, and contact pressure in response to a simulated quadriceps force when the knee was ACL deficient. Partial ACL injury was simulated by reducing the stiffness of the ACL in the model. The results demonstrated that even with a reduction of 75% of the ACL stiffness, the ACL still carried a significant amount of the load (more than 58%) carried by an intact ACL. The kinematics (both tibial translation and rotation) varied less than 20% compared to that of the knee with intact ACL. The 3D computational model can be a powerful tool to simulate different variables that would influence knee function after ACL reconstruction, such as the initial tension of the ACL graft, the insertion sites of the graft, multibundle grafts, graft materials, and various physiological loading conditions. © 2002 Biomedical Engineering Society. PAC2002: 8719Ff, 8719Rr, 8719St     

Predicting the effects of knee focal articular surface injury with a patient-specific finite element model

Successful focal articular surface injury (FAI) repair depends on appropriate matching of the geometrical/material properties of the repaired site, and on the overall dynamic response of the knee to in-vivo loading. There is evidence linking the pathogenesis of lesion progression (e.g. osteoarthritis) to weightbearing site and defect size. The paper investigates further this link by studying the effects of osteochondral defect size on the load distribution at the human knee. Experimental data from cadaver knees (n = 8) loaded at 30° of flexion was used as input to a validated finite element (FE) model. Contact pressure was assessed for the intact knees and over a range of circular osteochondral defects (5 mm to 20 mm) at 30° of flexion with 700 N axial load. Patient specific FE models and the specific boundary conditions of the experimental set-up were used to analyze the osteochondral defects. Stress concentration around the rims of defects 8 mm and smaller was not significant and pressure distribution was dominated by the menisci. Experimental data was confirmed by the model. For defects 10 mm and greater, distribution of peak pressures followed the rim of the defect with a mean distance from the rim of 2.64 mm on the medial condyle and 2.90 mm on the lateral condyle (model predictions were 2.63 and 2.87 mm respectively). Statistical significance was reported when comparing defects that differed by 4 mm or greater (except for the 5 mm case). Peak rim pressure did not significantly increase as defects were enlarged from 10 mm to 20 mm. Peak values were always significantly higher over the medial femoral condyle. Although the decision to treat osteochondral lesions is multifactorial, the results of this finite element analysis indicate that a size threshold of 10 mm, may be a useful early adjunct to guide clinical decision-making. This modified FE method can be employed for in-vivo studies.     

利用步态分析研究楔形鞋垫对膝关节载荷的影响

目的研究足底不同位置的楔形鞋垫对膝关节承载及运动特征的影响。方法利用三维动捕捉系统与测力台对10名健康成年女性受试者步态中的关节动力学变化特点进行分析研究。实验状态分为对照组和6组楔形鞋垫测试组。利用单因素方差分析评价楔形足底支撑对膝关节动力学参数的影响。结果相对于对照组,前内侧楔形鞋垫组显著减小了膝内翻力矩第1峰值(P<0.05);使用前外侧楔形鞋垫和外侧全长楔形鞋垫的两组显著减小了膝内翻力矩第2峰值(P<0.05,P<0.05)。结论使用楔形鞋垫可有效地减小站立相的膝关节内翻力矩,这将有助于设计适合的鞋垫以减轻由骨性关节炎所带来的疼痛。     

Anatomy of the rat knee joint and fibre composition of a major articular nerve

Several recent reports discuss the role of joint nerves in arthritis. Many of these are based on studies in the rat. The aim of this study is to examine the anatomy of the rat knee joint, in search for a primary articular nerve, and to analyze the fibre composition of that nerve. The results show that the structure of the joint differs in some respects from the human knee. At the upper end of the bony patella a cartilaginous patella extends proximally, forming the anterior wall of the suprapatellar bursa. Distinct collateral ligaments are integrated in the joint capsule. The extensor digitorum longus muscle bridges the knee joint, originating from the lateral femoral epicondyle. The well-developed menisci contain pyramid-shaped ossicles. The cruciate ligaments are arranged like in the human knee. A large posterior (PAN) and a small medial (MAN) articular nerve can be identified. The PAN is composed of some 400 axons, about 80% of which are unmyelinated. All myelinated fibres are sensory. They present a unimodal size spectrum with a size range of 1-8 microns, and a predominance of small fibres. Specific denervations indicate that about 1/3 of the unmyelinated axons represent afferents, and some 2/3 are sympathetic efferents. Interestingly, neonatal capsaicin treatment did not influence the number of unmyelinated PAN axons. The functional significance of the numerous unmyelinated sympathetic and sensory PAN axons in the normal knee joint remains to be elucidated.     

Development of the human knee joint

ABSTRACT Background: Many studies have been published on the development of the human knee joint, but different investigators disagree on its morphogenetic time table. Most discrepancies center on the cavitation of the knee joint and the participation of the superior tibiofibular joint in the joint knee system. Methods: We summarize our observations of the development of the knee joint in 50 serially sectioned human embryonic and fetal lower limbs (26 embryos and 24 fetuses). Results: The epiphysis of the femur and tibia become condryfied from O'Rahilly stage 18, and ossification begins during the 13th week of development. The patella appears as a dense blastema during O'Rahilly stage 19, becomes condryfied during O'Rahilly stage 22, and begins its ossification during the 14th week of development. The knee joint cavity appears during O'Rahilly stage 22, initially as the femoropatellar joint. This process begins at the periphery of the articular interzone. The superior tibiofibular joint communicates with the lateral meniscotibial joint between 10 and 11 weeks of development and becomes separated from the 13 week on. The menisci arise from the eccentric portions of the articular interzone during O'Rahilly stage 22; however, until week 9 of development, they are not easily distinguishable. Conclusions: We establish the morphogenetic time table of the human knee joint. Anat. Rec. 248:269-278, 1997. © 1997 Wiley-Liss, Inc.     

Diagnosis of knee prosthetic joint infection; aspiration and biopsy

BackgroundProsthetic joint infection (PJI) is a significant cause of morbidity and mortality following knee replacement surgery. The diagnosis can be challenging and is based on a combination of clinical suspicion, radiographic findings and also biochemical/ microbiological investigations. Our Aim was to review the role of aspiration and biopsy in the diagnosis of PJI in Total Knee Arthroplasty (TKA).Method/resultsAspirated synovial fluid should be analysed by direct culture, via blood culture bottles, EDTA bottles for cell count and ‘point of care’ testing such as leucocyte esterase or alpha defensin. Synovial WCC and PMN cell percentage are important steps in diagnosis of both acute and chronic PJI. A minimum of 5 deep samples using a 5 clean instrument technique should be obtained and sent for tissue culture done either blind or arthroscopic. Formal fluoroscopic guided interface biopsy has also been described with excellent results. In a recent series of 86 TKRs preoperative arthroscopic biopsy group had a sensitivity of 100%, specificity of 94.7%, positive predictive value of 87.4% and a negative predictive value of 100%.ConclusionIn the presence of clinical suspicion with raised biomarkers, it is recommended that aspiration +/- biopsy with synovial fluid testing is performed. Direct culture and cell count are recommended. ‘Point of care tests’ such as Leucocyte Esterase testing should be considered. Duration of culture, including pathogen and host factors, should be discussed with a local microbiology/ID department in the context of a formal multi-disciplinary team.     

Chronic septic arthritis and osteomyelitis in a prosthetic knee joint due toClostridium difficile

A case of chronic septic arthritis and osteomyelitis in a prosthetic knee joint due toClostridium difficile is reported. A knee prosthesis was installed in a 16-year-old boy for surgical treatment of an osteosarcoma of the femur. Later, the patient suffered a traumatic closed fracture of his patella, and a sterile fluid was aspirated. One month later, the joint displayed inflammation. Culture of the articular fluid yielded a nontoxigenicClostridium difficile strain. Despite several attempts using conservative medical treatment with penicillins and ornidazole,Clostridium difficile strains with the same antibiotic susceptibility pattern were repeatedly isolated from the joint over an eight-month period. The foreign material was then ablated, and finally, the patient's leg was amputated one year afterClostridium difficile was first isolated. The possible sources of contamination in our case and other reported cases of extraintestinal infection due toClostridium difficile are discussed.     

Influence of hysteresis on joint position sense in the human knee joint

During muscle lengthening in a movement cycle the firing rate of muscle spindles is higher than during shortening. This phenomenon, known as hysteresis, has implications for movement control. Therefore, it should have an impact on joint position sense (JPS), the subject's awareness of the static position of a joint. JPS has been tested on the human knee joint by means of an angle reproduction test. This task included the following sequences. The leg was moved passively, by means of a motor drive, from two different start positions (15 degrees and 75 degrees) to a certain target angle and, after a time of 8 s, it was returned to the start position; subjects had to reproduce the former target angle. Several target angles, mild flexion (30 degrees), intermediate flexion (45 degrees), and strong flexion (60 degrees), were used. Depending on the start position, the movements matching these targets were flexions or extensions. At least for the intermediate position different threshold values should be expected for flexions and extensions, if hysteresis has an impact. Moreover, the JPS measure should show a dependence on movement velocity and independence on distance. Of the variables tested, only movement direction but not movement velocity or distance had a statistically significant impact on the dependent constant angle error (difference between reproduction and target angle). The target angle of 30 degrees was exactly reproduced (-0.14 degrees), independently of the start position. The 45 degrees target angle was significantly underestimated (-4.39 degrees) when matching that position by flexions (starting at 15 degrees) compared to an overestimation (2.27 degrees) when matching that position by extensions (starting at 75 degrees). The target angle of 60 degrees has been constantly underestimated (-3.80 degrees), independently of the start position. Therefore, hysteresis, the dependency of the movement's direction, neglected in the past, should be considered in future tests of JPS or studies considering the role of movement parameters for motor control.     

Anatomic bases of a vascularized allogenic knee joint transplantation: arterial blood supply of the human knee joint

Summary The vitality of a graft in a vascularized allogenic knee joint transplantation in humans will depend strongly on maintaining the arterial blood supply to the bone. As can be demonstrated in injected specimens on cadavers, only periostal aa. are important to ensure the blood supply of the human knee joint. The main arteries have defined nutritive areas. According to our results access to the vessels should most probably be conducted from the dorsal side of the knee. During the explantation the popliteal a. should be ligated proximally as high up as possible and distally just above its trifurcation. The articular branch of the descending genicular a. of both the donor and the recipient can be ligated because of a rich anastomotic network. The medial and lateral inferior genicular aa. of the donor should be ligated ventrally as far forward as possible. One should, above all, preserve the medial inferior genicular a. of the donor in order not to endanger the medial part of the distal segment of the graft. If an operation is to be performed according to the results of our anatomical studies, vascularized allogenic knee joint transplantations should be successful from an anatomical point of view.

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Bases anatomiques de la transplantation d'une allogreffe vascularisée de genou : vascularisation artérielle de l'articulation du genou humain

Résumé La vitalité d'une greffe lors d'une transplantation d'allogreffe vascularisée de genou dépendra principalement du maintien de la vascularisation artérielle de l'os. Comme on peut le montrer sur des spécimens cadavériques injectés, seules les artères périostées sont importantes pour assurer la vascularisation artérielle du genou humain. Les principales artères ont des territoires définis. En fonction de nos résultats, l'accès aux vaisseaux serait au mieux mené par le versant dorsal du genou. Pendant le prélèvement, l'a. poplitée devrait être sectionnée proximalement aussi haut que possible, et distalement juste au-dessus de sa trifurcation. Le rameau articulaire de l'a. descendante du genou du donneur et celui du receveur peuvent être liées en raison du riche réseau anastomotique. Les aa. géniculées inféro-médiale et inféro-latérale du donneur devraient être liées aussi loin que possible en avant. Il faudrait par dessus tout préserver l'artère géniculée inféromédiale du donneur pour éviter de léser la partie médiale du segment distal de la greffe. Si une transplantation d'un allogreffe vascularisée de genou devait être réalisée en tenant compte du résultat de nos travaux, elle devrait être un succès du point de vue anatomique.

     

Development of the human knee joint ligaments

ABSTRACT Background: Many studies have been published on the development of the human knee joint, but scant attention has been given to the development of the knee joint ligaments. The only elements that have received much attention are the cruciate ligaments and their relationships with the synovial membrane. Methods: We summarize our observations on the development of the knee joint ligaments in 50 serially sectioned human embryonic and fetal lower limbs (26 embryos and 24 fetuses). Results: The patellar ligament begins to form in O'Rahilly stage 20, with the muscle fibers of the quadriceps muscle being attached inferiorly to the tibial tuberosity. The cruciate ligaments (beginning with the posterior) arise from the articular interzone in O'Rahilly stage 21. Subsequently, with the organization of the Wrisberg's meniscofemoral ligament, in week 10 of development, the cruciate ligament system is completed. The lateral collateral ligament begins to form in O'Rahilly stage 23, and from its first appearance it is independent of the knee joint capsule. At this time, development of the tendon of the popliteus muscle begins. The medial collateral ligament begins to develop in week 9 of development as a condensation of the joint capsule. Two weeks later, the intra-articular pad of fat begins to form from mesenchymal tissue below the patella and between the cruciate and the patellar ligaments. With the organization of the suprapatellar bursa in week 14 of development, knee joint development is complete. Conclusions: The morphogenetic time table of the knee joint ligaments was established. Anat. Rec. 248:259-268, 1997. © 1997 Wiley-Liss, Inc.