人体关节活动度测量系统

关节活动度是康复学中鉴定肢体伤残等级和评定关节康复程度的一项重要指标。目前常用的测量方法有通用量角器、照相法和X光,但这些方法在精度、稳定性和实时性方面都无法满足临床需要。本文提出了将光学定位设备NDI Polaris Spectra应用于人体关节活动度的测量,从而提高精确度、可重复性和实时性。本方法首先将反光小球固定在人体的骨性标志点上,然后利用NDI Polaris Spectra追踪反光小球的位置。NDI Polaris Spectra会将反光小球的三维坐标数据反馈给计算机,根据这些反光小球的三维坐标数据使用最小二乘法拟合出肢体运动的轨迹和轴心,从而计算出关节运动的角度。该方法测量结果的精度可以达到0.5°,标准差不超过0.02°,精度和稳定性都优于现有方法,足以满足临床需要。     

Control of the wrist joint in humans

As one considers changes in motor activity from lower mammals to higher primates, one of the major changes one observes lies in the cortical control of forelimb muscles. There has been a shift from disynaptic control of spinal motoneurons in, for example, the cat, to a greater and greater percentage of monosynaptic control of hand and forelimb motoneurons in the primate. In spite of the species and evolutionary changes in the synaptic connections of the corticospinal tract, it appears that the interneurons identified in the cat are retained in the monkey and human. These interneurons, under the influence of descending pathways, modulate the output of motoneuron pools. Perhaps the control of these interneurons has also changed towards finer control of movement, as has been suggested by recent studies in the monkey. Whether in cat or human, the recruitment pattern for motor units is the same; the change from disynaptic to monosynaptic connections has not changed the recruitment pattern of muscles. Differences in the recruitment patterns of muscles may lie in the finer control of inputs to motoneurons in the primate. This review seeks to integrate the current knowledge of the mechanisms involved in the motor control of the wrist joint and especially in the recruitment patterns of the muscles. These motor control mechanisms include the biomechanics of the wrist joint, recruitment patterns of wrist muscles, interneurons and spinal cord circuits in the cervical regions mediating the output of spinal motoneurons, and the supraspinal control of these muscles. Accepted: 30 May 2000     

桡骨短缩对桡腕关节影响的生物力学研究

目的:研究桡骨远端骨折后桡骨短缩对桡腕关节的影响。方法:12只成人上肢标本于距关节面3 cm处截骨去除1 cm骨块,使骨块可向近端移动,制作桡骨远端骨折后桡骨短缩模型,利用压敏片测试桡腕关节面的应力分布和受力面积改变情况。结果:随着桡骨短缩的增加,舟骨的接触面积无显著变化(P>0.01),接触应力显著增大(P<0.01);月骨的接触面积轻度增加,接触应力显著增大(P<0.01),桡骨短缩≥4 mm时即有显著变化,桡骨短缩≥4-6 mm造成尺骨撞击三角骨。结论:桡骨远端骨折短缩4 mm以上时,接触应力有显著变化,影响腕关节功能。     

Characteristics of wrist joint receptors in the cat

Summary A branch of the dorsal interosseous nerve is described, which innervates the dorsal aspect of the wrist joint capsule of the cat. Recordings of the whole wrist joint nerve showed no tonic activity until the wrist was flexed to within 45 ° of full flexion (about one third of the normal range). There was no tonic activity at full extension or at intermediate positions. 110 single afferents from the wrist joint capsule were isolated from dorsal root filaments. Their responses to movement of the wrist and other mechanical stimuli were examined, and their conduction velocities measured. 31 were slowly adapting, 41 were phasic, 9 were Pacinian corpuscle-like, 7 were weakly activated, and 22 were not activated by the mechanical stimuli which were used. Slowly adapting receptors responded only when the joint was in a flexed position as would be expected from the whole nerve data. Conduction velocities for the 4 classes of responding mechanoreceptors were not significantly different, and fell in the group II range. Fibre diameter histograms of myelinated axons in the wrist joint nerve showed peaks in the group II and group III range. Intravenous injection of succinylcholine showed no increase in whole nerve activity attributable to muscle spindles, and had a negligible effect on identified receptors in the wrist joint capsule.     

Measurement of cell traction force with a thin film PDMS cantilever

Adherent cells produce cellular traction force (CTF) on a substrate to maintain their physical morphologies, sense external environment, and perform essential cellular functions. Precise characterization of the CTF can expand our knowledge of various cellular processes as well as lead to the development of novel mechanical biomarkers. However, current methods that measure CTF require special substrates and fluorescent microscopy, rendering them less suitable in a clinical setting. Here, we demonstrate a rapid and direct approach to measure the combined CTF of a large cell population using thin polydimethylsiloxane (PDMS) cantilevers. Cells attached to the top surface of the PDMS cantilever produce CTF, which causes the cantilever to bend. The side view of the cantilever was imaged with a low-cost camera to extract the CTF. We characterized the CTF of fibroblasts and breast cancer cells. In addition, we were able to directly measure the contractile force of a suspended cell sheet, which is similar to the CTF of the confluent cell layer before detachment. The demonstrated technique can provide rapid and real-time measurement of the CTF of a large cell population and can directly characterize its temporal dynamics. The developed thin film PDMS cantilever can be fabricated affordably and the CTF extraction technique does not require expensive equipment. Thus, we believe that the developed method can provide an easy-to-use and affordable platform for CTF characterization in clinical settings and laboratories.     

Measurement of wheelchair contact force with a low cost bench test

In mechanical engineering, it is well established that contact between the tire and the ground is a key parameter in characterizing the dynamic behavior of vehicles and an important factor in design control. Therefore, it is an important part of dynamic simulation models for vehicles, including wheelchairs. This work presents a bench test designed to experimentally monitor and measure the forces transmitted to the ground by a moving wheel. The test bench is composed of a table and a track with a fixed wheel structure and powertrain system. The table is an integrated structure that measures the longitudinal and lateral forces produced by tire contact. This table allows characterization of the tire and tests the tire under varying loads at different slip and camber angles. Additionally, the test bench can also be used to evaluate other tires, such as caster tires. The performances of the new device are illustrated, and the results show the differences between tires, which are related to the dynamic behaviors of wheelchair model. Finally, preliminary experiments performed using the test bench have shown that it is able to monitor and measure the forces generated by the contact between the tire and the ground.     

Damping of the wrist joint during voluntary movement

Damping characteristics of the musculoskeletal system were investigated during rapid voluntary wrist flexion movements. Oscillations about the final position were induced by introducing a load with the characteristics of negative damping, which artificially reduced the damping of the wrist. Subjects responded to increases in the negatively damped load by stronger cocontraction of wrist flexor and extensor muscles during the stabilization phase of the movement. However, their ability to counteract the effects of the negatively damped load diminished as the negative damping increased. Consequently, the number and frequency of oscillations increased. The oscillations were accompanied by phase-locked muscle activity superimposed on underlying tonic muscle activation. The wrist stiffness and damping coefficient increased with the increased cocontraction that accompanied more negatively damped loads, although changes in the damping coefficient were less systematic than the stiffness. Analysis of successive half-cycles of the oscillation revealed that the wrist stiffness and damping coefficient increased, despite decreasing muscle activation, as oscillation amplitude and velocity declined. This indicates that the inverse dependence of the damping coefficient on oscillation velocity contributes significantly to damping of joint motion. It is suggested that this property helps to offset a negative contribution to damping from the stretch reflex. Received: 3 September 1997 / Accepted: 9 April 1998     

第1跖趾关节相关生物力学研究进展

第1跖趾关节既参与前足横弓的构成,又是足内侧纵弓的重要组成部分,在维持足弓牛物力学稳定方面起着举足轻重的作用,其稳定性的破坏会引起前足生物力学的改变从而严苇影响足部负重和行走功能的有效行使,临床上(足)外翻、前跖痛等许多足部疾病的发生发展均与第1跖趾火节稳定性的破坏有关,本文主要就第1跖趾关节相关牛物力学的研究进展作一综述.     

Subject-specific evaluation of patellofemoral joint biomechanics during functional activity

Patellofemoral joint pain is a common problem experienced by active adults. However, relatively little is known about patellofemoral joint load and its distribution across the medial and lateral facets of the patella. In this study, biomechanical experiments and computational modeling were used to study patellofemoral contact mechanics in four healthy adults during stair ambulation. Subject-specific anatomical and gait data were recorded using magnetic resonance imaging, dynamic X-ray fluoroscopy, video motion capture, and multiple force platforms. From these data, in vivo tibiofemoral joint kinematics and knee muscle forces were computed and then applied to a deformable finite-element model of the patellofemoral joint. The contact force acting on the lateral facet of the patella was 4–6 times higher than that acting on the medial facet. The peak average patellofemoral contact stresses were 8.2 ± 1.0 MPa and 5.9 ± 1.3 MPa for the lateral and medial patellar facets, respectively. Peak normal compressive stress and peak octahedral shear stress occurred near toe-off of the contralateral leg and were higher on the lateral facet than the medial facet; furthermore, the peak compressive stress (11.5 ± 3.0 MPa) was higher than the peak octahedral shear stress (5.2 ± 0.9 MPa). The dominant stress pattern on the lateral patellar facet corresponded well to the location of maximum cartilage thickness. Higher loading of the lateral facet is also consistent with the clinical observation that the lateral compartment of the patellofemoral joint is more prone to osteoarthritis than the medial compartment. Predicted cartilage contact stress maps near contralateral toe-off showed three distinctly different patterns: peak stresses located on the lateral patellar facet; peak stresses located centrally between the medial and lateral patellar facets; and peak stresses located superiorly on both the medial and lateral patellar facets.     

全膝关节置换后关节线变化对髌股关节生物力学的影响

BACKGROUND: In addition to infection, the reasons for total knee arthroplasty revision are polyethylene liner wear and prosthesis loosening. The impact of joint line height on patellofemoral biomechanics was inconclusive. OBJECTIVE: To study the impact of joint line changes after total knee arthroplasty on patellofemoral joint biomechanics. METHODS: Three-dimensional finite element models were established after total knee arthroplasty. The impact of different joint line height on quadriceps tensile force, patella tendon tension, and patellofemoral joint forces was calculated at range of flexion of 0°, 30°, 60° and 90°.  RESULTS AND CONCLUSION: (1) At knee flexion of 0°, the height of the joint line in -3 mm-4.5 mm did not have great impacts on quadriceps tensile force, patella tendon tension and patellofemoral joint forces. (2) At knee flexion of 30°-90°, the height of the joint line below 3 mm did not have great impacts on quadriceps tensile force, patella tendon tension and patellofemoral joint forces. The height of the joint line more than 3 mm had obvious impacts on quadriceps tensile force, patella tendon tension and patellofemoral joint forces. (3) It was recommended that the height of joint line in total knee arthroplasty was preferably controlled within 3 mm.      

肌骨模型在膝关节生物力学研究中的应用进展

肌骨模型是基于生理学、工程分析和计算机三维图像技术的用于分析人体运动系统中肌肉与骨骼之间相对位置关系的几何模型,是分析人体生物力学特性的基础,由于其在研究人体肌肉骨骼系统生物力学上的优越性而越来越多地被应用.就肌骨模型在膝关节生物力学研究中的应用进展作一综述.     

Dynamic CT technique for assessment of wrist joint instabilities

Purpose: To develop a 4D [three-dimensional (3D) + time] CT technique to capture high spatial and temporal resolution images of wrist joint motion so that dynamic joint instabilities can be detected before the development of static joint instability and onset of osteoarthritis (OA).Methods: A cadaveric wrist was mounted onto a custom motion simulator and scanned with a dual source CT scanner during radial-ulnar deviation. A dynamic 4D CT technique was utilized to reconstruct images at 20 equidistant time points from one motion cycle. 3D images of carpal bones were generated using volume rendering techniques (VRT) at each of the 20 time points and then 4D movies were generated to depict the dynamic joint motion. The same cadaveric wrist was also scanned after cutting all portions of the scapholunate interosseus ligament to simulate scapholunate joint instability. Image quality were assessed on an ordinal scale (1-4, 4 being excellent) by three experienced orthopedic surgeons (specialized in hand surgery) by scoring 2D axial images. Dynamic instability was evaluated by the same surgeons by comparing the two 4D movies of joint motion. Finally, dose reduction was investigated using the cadaveric wrist by scanning at different dose levels to determine the lowest radiation dose that did not substantially alter diagnostic image quality.Results: The mean image quality scores for dynamic and static CT images were 3.7 and 4.0, respectively. The carpal bones, distal radius and ulna, and joint spaces were clearly delineated in the 3D VRT images, without motion blurring or banding artifacts, at all time points during the motion cycle. Appropriate viewing angles could be interactively selected to view any articulating structure using different 3D processing techniques. The motion of each carpal bone and the relative motion among the carpal bones were easily observed in the 4D movies. Joint instability was correctly and easily detected in the scan performed after the ligament was cut by observing the relative motion between the scaphoid and lunate bones. Diagnostic capability was not sacrificed with a volume CT dose index (CTDI(vol)) as low as 18 mGy for the whole scan, with estimated skin dose of approximately 33 mGy, which is much lower than the threshold for transient skin erythema (2000 mGy).Conclusions: The proposed dynamic 4D CT imaging technique generated high spatial and high temporal resolution images without requiring periodic joint motion. Preliminary results from this cadaveric study demonstrate the feasibility of detecting joint instability using this technique.     

Application of robotic technology in biomechanics to study joint laxity

Primary objective:?To evaluate whether in vitro joint testing using a robot with six degrees of freedom is useful for evaluating changes in joint laxity as a result of chronic osteoarthritis (OA).

Research design:?Repeated measures.

Methods:?Broyden's method of solving nonlinear systems of equations drove a hybrid method of load and position robotic control. Sheep stifles (knee joints) were loaded between 3 Nm of internal load through to 3 Nm of external load in 1 Nm increments. Kinematic and morphologic data from five healthy ovine stifles were compared to the chronic OA effects in four surgically destabilized stifles.

Results:?Stifles with chronic OA showed increases in stiffness while range of motion decreased. Gross morphologic changes included osteophytes and cartilage fibrillation.

Discussion:?Robotic testing proved useful for evaluating changes in joint mechanics as a result of chronic OA. We observed morphological changes and associated increases in joint stiffness and decreased laxity.     

Receptors in the knee joint ligaments and their role in the biomechanics of the joint

The knee joint ligaments contain Ruffini, Pacinian, Golgi, and free-nerve endings with different capabilities of providing the CNS with information about movement and position as well as about noxious events. Skeletomotor neurons (alpha-motoneurons) are known to be influenced only very rarely and weakly from low-threshold mechanoreceptors in the ligaments, while the effects on the tau-muscle-spindle system in the muscles around the knee are so potent that even ligament stretches at very low loads may induce major changes in the responses of the muscle spindle afferents. Since the primary muscle spindle afferents participate in the regulation of muscular stiffness, the receptors in the knee joint ligaments probably contribute, via the tau-muscle-spindle system, to preparatory adjustment (pre-setting) of the stiffness of the muscles around the knee joint, and thereby to the joint stiffness and the functional joint stability.     

膝关节后外侧结构生物力学的有限元分析

背景：有限元分析作为一种数值分析手段,适用于三维人体结构力学模型的生物力学分析。 目的：采用有限元分析膝关节后外侧结构主要韧带(外侧副韧带、腘肌腱和腘腓韧带)的生物力学特点。 方法：建立人膝关节包括后外侧结构的三维有限元模型,在模型上施加胫骨的前后向力、内外翻力矩、内外旋力矩,观察膝关节后外侧韧带在完整和缺失时的应力响应。 结果与结论：膝关节后外侧结构对限制膝关节的内翻、外旋和胫骨后移有重要作用,而对限制胫骨前移、外翻和内旋的作用并不明显。膝关节后外侧结构损伤对膝关节的稳定性有明显影响。在膝关节后外侧结构中起主要作用的是外侧副韧带,其次是腘肌腱,而腘腓韧带在后外侧结构中起辅助作用。     

4D rotational x-ray imaging of wrist joint dynamic motion

Current methods for imaging joint motion are limited to either two-dimensional (2D) video fluoroscopy, or to animated motions from a series of static three-dimensional (3D) images. 3D movement patterns can be detected from biplane fluoroscopy images matched with computed tomography images. This involves several x-ray modalities and sophisticated 2D to 3D matching for the complex wrist joint. We present a method for the acquisition of dynamic 3D images of a moving joint. In our method a 3D-rotational x-ray (3D-RX) system is used to image a cyclically moving joint. The cyclic motion is synchronized to the x-ray acquisition to yield multiple sets of projection images, which are reconstructed to a series of time resolved 3D images, i.e., four-dimensional rotational x ray (4D-RX). To investigate the obtained image quality parameters the full width at half maximum (FWHM) of the point spread function (PSF) via the edge spread function and the contrast to noise ratio between air and phantom were determined on reconstructions of a bullet and rod phantom, using 4D-RX as well as stationary 3D-RX images. The CNR in volume reconstructions based on 251 projection images in the static situation and on 41 and 34 projection images of a moving phantom were 6.9, 3.0, and 2.9, respectively. The average FWHM of the PSF of these same images was, respectively, 1.1, 1.7, and 2.2 mm orthogonal to the motion and parallel to direction of motion 0.6, 0.7, and 1.0 mm. The main deterioration of 4D-RX images compared to 3D-RX images is due to the low number of projection images used and not to the motion of the object. Using 41 projection images seems the best setting for the current system. Experiments on a postmortem wrist show the feasibility of the method for imaging 3D dynamic joint motion. We expect that 4D-RX will pave the way to improved assessment of joint disorders by detection of 3D dynamic motion patterns in joints.     

踝关节三维有限元生物力学研究的临床转化

背景：踝关节是人体的负重、足部压力的缓冲和人体与地面接触的枢纽,极易受到损伤;骨科生物力学领域的研究不断成熟和发展,利用三维有限元软件建模分析踝关节生物力学并研究临床疾病逐渐成为研究热点。 目的：探讨踝关节三维有限元生物力学的研究现状,并对其临床研究进展作一综述。 方法：应用计算机检索CNKI期刊全文数据库和PubMed数据库中1986年1月至2014年3月关于踝关节有限元的文章,以“踝关节、有限元、生物力学、力学研究”或“ankle, finite element, biomechanics, mechanics research”为检索词进行检索;排除与研究目的无关和内容重复的文献;保留47篇文献进行综述。 结果与结论：踝关节生物力学机制复杂,各种损伤后都可能打破其周围结构的力学平衡而导致不稳定,诱发创伤性关节炎。踝关节三维有限元模型可准确反映解剖学结构特点、虚拟仿真可以再现手术方式及过程逼真的模拟,模拟压缩、拉伸、弯曲、扭转、抗疲劳等力学实验,并从静态的生物力学转向动态的方向研究,为分析临床疾病进而找到更合适的诊治方案。中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程全文链接：