正走和倒走的膝关节生物力学特征比较

目的 比较正走和倒走两种不同行走模式时膝关节的生物力学特征。方法 采用三维运动捕捉系统Vicon T40和测力台AMTI OR6-7采集并比较13名健康青年男性志愿者正走和倒走时的时间、空间、运动学和动力学参数。结果 与正走相比,倒走时的步速、步频和步幅均显著减小,跨步周期和支撑相所占百分比显著增加;在矢状面上,倒走时膝关节活动度、最大屈伸力矩较正走小;在冠状面上,倒走时膝关节内翻外展活动范围也较正走小,内翻力矩峰值在支撑早期较正走小,但在支撑晚期较正走大;地面反作用力在支撑早期较正走大,但在支撑晚期较正走小。结论 倒走和正走膝关节生物力学特征差异明显。与正走相比倒走在支撑相早期能减轻膝关节内侧间室的负荷,而倒走在支撑相晚期对膝关节负荷的影响则尚须进一步研究。     

Age-related changes in lower trunk coordination and energy transfer during gait

The effects of aging on lower trunk (trunk-low-back joint-pelvis) coordination and energy transfer during locomotion has received little attention; consequently, there are scant biomechanical data available for comparison with patient populations whose upper body movements may be impaired by orthopaedic or neurologic disorders. To address this problem, we analyzed gait data from a cross-sectional sample of healthy adults (n = 93) between 20 and 90 yr old (n = 44 elderly, >50 yr old; n = 49 young, <50 yr old). Gait characteristics of elders were mostly typical: gait speed of elders (1.13 +/- 0.20 m/s) was significantly (P = 0.007) lower than gait speed of young subjects (1.20 +/- 0.18 m/s). Although elders had less low-back (trunk relative to pelvis) range of motion (ROM; P = 0.013) during gait than young subjects, no age-related differences were detected in absolute trunk and pelvis ROM or peak pitch angles during gait. Despite similar upper body postures, there was a strong association between age and pelvis-trunk angular velocity phase angle (r = 0.48, P < 0.001) with zero phase occurring at approximately 55 yr of age; young subjects lead with the pelvis while elderly subjects lead with the trunk. Age related changes in gait speed and low-back ROM were unable to explain the above findings. The trunk-leading strategy used by elders resulted in a sense reversal of the low-back joint power curve and increased (P = 0.013) the mechanical energy expenditure required for eccentric control of the lower trunk musculature during stance phase of gait. These data suggest an age-related change in the control of lower trunk movements during gait that preserves upper body posture and walking speed but requires a leading trunk and higher mechanical energy demands of lower trunk musculature-two factors that may reduce the ability to recover from dynamic instabilities. The behavioral and motor control aspects of these findings may be important for understanding locomotor impairment compensations in aging humans and in quantifying falls risk.     

痉挛型脑瘫患者功能性选择性脊神经后根切断术前后的三维步态特征分析

目的分析痉挛型脑瘫患者功能性选择性脊神经后根切断(functional selective posterior rhizotomy,FSPR)手术前后的步态特征,客观量化评估手术疗效。方法选取15名将要进行FSPR手术治疗的痉挛型脑瘫患者,应用VICON三维运动捕捉系统结合AMTI三维测力台对患者进行手术前后的步态采集,分析手术前后步态的时空、运动学及动力学参数。结果手术后,左、右支撑时间均大于手术前,左侧步长明显大于手术前,步高、步速及冠状面重心偏移均小于手术前;着地时的膝关节矢状面角度(即屈伸角度)出现明显提高,髋、踝关节未见明显差异。手术后,步行过程中左右侧髋、膝、踝关节活动范围(range of motion,ROM)在矢状面均出现不同程度的提高,且有统计学差异;右踝关节冠状面ROM也出现明显提高。手术后,右膝关节最小屈曲角度及左、右踝关节最大跖屈角度均出现显著减小;左、右侧支撑相最大垂直力较手术前明显提高,而下肢关节力矩未见明显差异。结论三维步态分析可以在一定程度上评估痉挛型脑瘫患者FSPR手术的疗效。术后痉挛型脑瘫患者的痉挛得到缓解,对步态的时空参数及下肢关节运动学参数改善比较明显,而对于动力学参数改善相对不明显,需进行进一步康复治疗。     

人工颈椎间盘置换术与融合术的生物力学比较

目的 分析颈前路植骨融合术（anterior cervical discectomy and fusion,ACDF）与颈椎间盘置换术（total disc replacement,TDR）后颈椎生物力学特性。方法 采用12具人体颈椎标本,通过三维非接触式光电测量系统及位移控制方式,测试原始状态（intact）、TDR及ACDF术后各节段在前屈与后伸、左侧弯与右侧弯、左旋转与右旋转6种独立工况的运动和载荷分布,并探讨颈椎正常生理运动规律及植入器械特点。结果TDR术后,颈椎各节段运动保留效果明显,能恢复接近正常的运动,并以屈伸、旋转工况为优;同等工况下ACDF术后手术节段运动丢失达73.41%,其他节段运动也存在明显改变。侧弯工况两者均存在较大运动改变,TDR达45.92%,ACDF达108.06%。试验发现,颈椎正常生理运动为空间三轴耦合运动,以侧弯工况耦合程度最大,绕X轴运动分量达35%,TDR术后,颈椎能恢复接近正常的耦合运动规律。结论TDR术能使颈椎恢复更接近正常的生理运动,在屈伸、旋转工况效果最好,侧弯次之。本研究为TDR与ACDF的临床手术提供理论依据和定量参考。     

Proactive stability control while carrying loads and negotiating an elevated surface

In this study, proactive stability control while handling loads and negotiating an elevated surface was examined. Ten young healthy males completed two gait-mode conditions—level walking and negotiating a raised surface. Load-handling conditions were: no load, empty box (reduced visual information), and loaded box (reduced visual information combined with increased inertial load). The lower limb trajectory in the sagittal plane was not modified as a function of reduced visual information or increased inertial load. The step width decreased while stepping over the surface and carrying the loaded box. The trunk pitch angle was biased backwards for both the empty box and the loaded box. When carrying the empty box and negotiating the surface, the trunk pitch range of motion (ROM) increased which may have been a strategy to increase visual exteroceptive information. As increased net trunk pitch could destabilize the system, concurrent stabilizing strategies—decreased gait velocity and reduced net trunk roll velocity—were observed. To meet the equilibrium goals when carrying the loaded box, the trunk pitch ROM and net pitch velocity were reduced during both level walking and surface accommodation. Trunk roll ROM was reduced when carrying the load and negotiating the surface. This study extends our knowledge regarding whole body coordination strategies during anticipatory locomotor adaptations.     

偏瘫患者以不同步态模式通过障碍物的生物力学特征对比分析

目的 探讨偏瘫患者使用“健上患下”和“患上健下”步态模式通过障碍物的生物力学特征,为降低患者跌倒发生率提供理论依据。方法 采用Qualisys动作捕捉系统和三维测力台采集15名偏瘫患者正常行走、健上患下、患上健下通过障碍物的运动学和动力学数据,并对数据进行处理与分析。结果 与正常行走相比,健上患下和患上健下通过障碍物都不同程度增加了双侧的下肢活动幅度;与正常行走和健上患下相比,患上健下模式下患侧腿垂直地面反作用力出现较大波动,步态稳定性较差,具有较大跌倒风险。结论 患者通过障碍物时,对接触障碍物的一侧肢体关节活动幅度要求较高,患侧肢适应能力较差。在触地后单腿支撑期,垂直方向地面反作用力变化较大。当身体重量完全转移到该侧时,容易导致患者跌倒。相比患上健下,患者使用健上患下方式通过障碍物时能容易保持步态稳定性,降低跌倒风险。     

基于人体骨盆运动轨迹的康复辅助机构设计

针对临床康复医师提出在下肢行走障碍患者康复训练过程中,患者身体重心缺乏在左右两脚之间的横向移动能力,从而影响行走甚至导致跌倒的问题,本文通过健康人步态行走过程的骨盆运动特征,对复杂的骨盆运动学和运动轨迹进行分析,提炼出骨盆侧向移动的轨迹和范围。根据人体工学分析,设计辅助骨盆侧向移动的机构,配合康复机器人应用在下肢行走训练,使得康复训练更接近健康人的自然状态,有利于训练过程中机械设备和人的相互作用。此方法获得医生和治疗师们的高度评价,并通过仿真试验做出了验证。     

Upper extremity kinetics during Lofstrand crutch-assisted gait

A three-dimensional (3D) biomechanical model was developed to determine upper extremity kinematics and kinetics of persons walking with forearm crutches. Six-component load cells and strain gauges were installed in the crutches to determine crutch forces. A six-camera VICON motion system was used to acquire coordinate data from 24 reflective markers attached to the upper extremities and crutches. Joint axes for the wrist, elbow, and glenohumeral joints were defined and joint forces and moments were determined using inverse dynamics. Accuracy of the crutch instrumentation was established by simultaneously collecting force data from a Kistler forceplate and each crutch during crutch-assisted gait with the respective crutch tip contacting the forceplate. In order to demonstrate the application of this biomechanical model, upper extremity weight bearing forces, joint motion, and stride characteristics were recorded from a subject with T-12 incomplete spinal cord injury (SCI), using a crutch-assisted reciprocal four-point gait pattern. The peak net joint forces and moments were greater for the right arm opposite the weaker left lower extremity. The largest joint forces were directed superiorly (Fz) and the asymmetrical pattern of crutch use was consistent with lower extremity strength differences. During left leg weight acceptance, increased right wrist extension motion and moment were recorded, which may contribute to wrist pathology.     

Influences of walking speed change on the lumbosacral joint force distribution

To more understand the influence of the walking speed on the spinal joint force distribution, a three-dimensional biomechanical model was used to estimate the spine loads during human gait with three different walking speeds. This previously developed and validated model included a dynamic external model and an internal model with forces of disc, 8 major muscles, 2 ligaments and 2 facet joints at L5/S1 level. A linear optimization method was used to solve the internal model to estimate the L5/S1 spinal joint force distribution. The results of five young male subjects showed that the mean peak L5/S1 disc compressive forces on the slow, preferred and fast speeds were 2.28, 2.53, 2.95 body weight, respectively. The peak forces happened right after the heel strike and before completely toe off. The facet joint forces were generally increased with the walking speed increase, too. To reduce the loads on the spine, the slow walking is then recommended for the patients with low back pain or after spinal surgery.     

The effects of rocker sole and SACH heel on kinematics in gait

The rocker sole and solid-ankle cushion-heel (SACH) heels are the most commonly prescribed external shoe modification. Only a limited number of scientific evidence exists to support these interventions in clinical practice. The objective of this study was to determine the effects of rocker soles and SACH heels on kinematics during gait. In this study, we investigated the gait parameters during level walking, stair climbing and stair descending in healthy volunteers and assessed the effects of the modified shoes on the motion of the forefoot and hindfoot compared with the traditional shoes. Eleven normal subjects participated in this study. A six-camera motion analysis system was used to capture motion trajectories. The three-dimensional (3D) coordinates of the markers were used to calculate the angles of flexion-extension, valgus-varus, and internal-external rotation at the hindfoot and forefoot joints in a gait cycle by the custom software for foot kinematic analysis. The results showed that the rocker soles offer several advantages from the viewpoint of gait kinematics. The forefoot joint excursion in sagittal plane while wearing rocker shoes was significantly less than that while wearing traditional shoes during level walking, stair climbing and stair descending. It means that they could mimic the action of the forefoot joint, aid in roll off, and simulate forefoot dorsiflexion. Since the bony structures mechanically link the forefoot joint and hindfoot joint to a triplanar axis of motion, they could be used whenever there is minimal or no motion at the forefoot joint or hindfoot joint, because of, for example, fusion, fracture, cast immobilization, orthosis design, pain, or arthritis.     

In Vivo Changes in Dynamic Adjacent Segment Motion 1 Year After One and Two-Level Cervical Arthrodesis

Biomechanical cadaver testing indicates adjacent segment motion increases after one-level anterior cervical spine arthrodesis, and two-level arthrodesis exacerbates these effects. There is little in vivo evidence to support those biomechanical studies. The purpose of this study was to assess the effects of one- and two-level cervical arthrodesis on adjacent segment motion. Fifty patients received either one-level C56 arthrodesis or two-level C456 or C567 arthrodesis and were tested preoperatively (PRE) and 1 year postoperatively (1YR-POST) along with 23 asymptomatic controls. A validated CT model-based tracking technique was used to measure 3D vertebral motion from biplane radiographs collected during dynamic flexion-extension and axial rotation of the cervical spine. Head and adjacent segment intervertebral end-range range of motion (ROM) and mid-range ROM were compared between one-level and two-level arthrodesis patients and controls. Small (2.3° or less) but non-significant increases in adjacent segment end-range ROM were observed from PRE to 1YR-POST. Mid-range flexion-extension ROM in the C67 motion segment inferior to the arthrodesis and mid-range axial rotation ROM in the C45 motion segment superior to the arthrodesis increased from PRE to 1YR-POST (all p < 0.022). This study provides in vivo evidence that contradicts long-held beliefs that adjacent segment end-range ROM increases appreciably after anterior cervical arthrodesis and that two-level arthrodesis exacerbates these effects. Mid-range ROM appears to be more useful than end-range ROM for detecting early changes in adjacent segment motion after cervical spine arthrodesis.

     

基于躯干细化模型腰椎间盘突出症患者与健康人群在3种日常活动下的运动学差异

目的建立由不同腰椎节段和集成胸椎、骨盆构成的躯干细化模型,分析腰椎间盘突出症(lumbar disc herniation,LDH)患者与健康人群在3种日常活动下的运动学差异,并与采用全腰节段的躯干简略模型作对比,探讨进行LDH患者运动学分析时采用躯干细化模型的必要性。方法使用NDI运动捕捉系统采集15名健康男性和7名男性LDH患者在水平行走、躯干前屈、对侧拾物中各节段的运动角度,分别通过两种模型比较患者与健康人群的运动学差异。结果水平行走过程中,LDH患者胸椎节段和骨盆旋转增加,全腰节段运动角度无明显变化,但L4～5节段旋转角度显著减小;躯干前屈过程中,LDH患者所有腰椎节段屈伸角度都不同程度地减小,L3～4节段屈伸角度与健康人群差异性较大;对侧拾物过程中矢状面上的表现与躯干前屈类似,但LDH患者L3～4节段和L4～5节段侧弯角度显著低于健康人群。结论 LDH患者在日常活动中主要限制了损伤腰椎节段的运动。在某些运动中,只有躯干细化模型才能发现损伤腰椎节段的异常运动。因此,在进行LDH患者运动学分析时,有必要将腰椎细分成5个独立节段。     

脊柱颈胸结合部C5~T2三维有限元建模与验证

目的基于CT图像数据建立人体脊柱颈胸结合部C5~T2的三维有限元模型,并验证模型的正确性和有效性。方法采用Mimics、Geomagic和Hypermesh软件对人体脊柱颈胸结合部C5~T2椎体进行三维重建、模型修复和有限元前处理,对模型顶面施加±0.5、1、1.5、2 N·m扭矩,用于模拟人体前屈和后伸活动时所产生的载荷作用,使用ANSYS软件计算脊柱颈胸结合部C5~T2节段在前屈和后伸承受扭矩载荷作用时的关节活动度(range of motion,ROM),将计算结果与前人研究结果进行对比分析。结果人体脊柱颈胸结合部C5~T2三维模型中C5~6、C6~7、C7~T1和T1~2各节段椎体在1 N·m载荷作用下,前屈时ROM分别为4.30°、3.21°、1.66°和1.41°,后伸时ROM分别为3.47°、2.86°、0.96°和0.92°。前屈时最大应力出现在椎体前缘,后伸时椎体后缘出现较大应力。ROM和应力分布的趋势与前人研究结果相一致。结论建立的脊柱颈胸结合部三维模型精确逼真,符合脊柱颈胸结合部的生物力学特性,模拟结果可为临床病理研究和颈胸部手术术式的评价提供理论依据。     

Gait adaptations to simultaneous cognitive and mechanical constraints

Previous studies have shown that walking is not a purely automatic motor task but places demands on sensory and cognitive systems. We set out to investigate whether complex walking tasks, as when walking down a steeper gradient while performing a concurrent cognitive task, would demand gait adaptation beyond those required for walking under low-challenge conditions. Thirteen healthy young individuals walked at their self-selected speed on a treadmill at different inclinations (0, −5 and −10%). Gait spatio-temporal measures, pelvis angular excursion, and sacral centre of mass (CoM) motion were acquired while walking or while walking and performing a mental tracking task. Repeated-measures ANOVAs revealed that decreasing treadmill inclination from 0 to −10% resulted in significant decreased walking speed (P < 0.001), decreased stride length (P < 0.001), increased pelvis tilt (P = 0.006) and obliquity variability (P = 0.05), decreased pelvis rotation (P = 0.02), and increased anterio-posterior (A-P) CoM displacement (P = 0.015). Compared to walking alone, walking under dual-task condition resulted in increased step width (P < 0.001), and increased medio-lateral (M-L) CoM displacement (P = 0.039) regardless of inclination grade, while sagittal plane dynamics did not change. Findings suggest that gait adapts differently to cognitive and mechanical constraints; the cognitive system is more actively involved in controlling frontal than sagittal plane gait dynamics, while the reverse is true for the mechanical system. Finally, these findings suggest that gait adaptations maintain the ability to perform concurrent tasks while treadmill walking in healthy young adults.     

胸腰椎前路K形钢板内固定系统的生物力学评价

目的：对胸腰椎前路K形钢板内固定系统（K－plate）进行生物力学稳定性评价。方法：6例新鲜成人尸体胸腰椎（T11－L3）标本，制成前、中柱损伤模型，椎体间模拟植骨后，分别以－Zplate、K－plate固定，采用脊柱三维运动试验系统测试完整、损伤、Z-plate和K-plate等4种状态下脊柱节段的运动范围（ROM）。结果：K-plate固定后，前屈、后伸、左侧弯、右侧变运动方向上ROM与完整、损伤状态之间差异有显著性（P＜0．05）；左、右轴向旋转运动方向上ROM与损伤状态之间差异有显著性（P＜0．05），但与完整状态之间差异无显著性（P＞0．05）。Z－plate、K－plate固定状态之间6个运动方向上ROM差异均无显著性（P＞0．05）。结论：胸腰椎前路K形钢板内固定系统能有效恢复失稳胸腰椎的稳定性。     

动态固定位置对腰椎稳定性影响的实验研究

目的腰椎棘突间动态稳定装置Coflex是一种临床上腰椎退行性疾病手术治疗的器械,在置入时其U形底部与硬脊膜之间的距离是手术的关键,Coflex置入不同深度后对手术节段的影响是本文关注的问题。本文通过体外实验评估Coflex的U形底部与硬脊膜的距离对术后腰椎稳定性的影响。方法选取成年新鲜尸体腰椎(L1—L5)标本6具。每个标本按照实验过程分为6组模型:完整组(A组)、失稳组(B组)、10 mm安装组(C组)、5 mm安装组(D组)、0 mm安装组(E组)、融合组(F组)。对模型进行前屈/后伸、左右侧弯、左右旋转6个方向的运动测试,通过观察手术节段的运动角度和关节活动度(range of motion,ROM)来分析其稳定性。结果各实验组手术节段运动角度与完整组的相似性为E组D组C组B组F组;ROM的计算结果显示,E组的ROM值比其他组相对较小,刚度较大。结论前屈后伸、左右侧弯、左右旋转6种方向运动时,棘突间动态稳定装置Coflex置入位置距脊柱较近时,术后手术节段性能更加接近正常腰椎。     

基于非线性时间序列法研究人体步行稳定性

目的应用非线性时间序列分析方法,研究健康老年与青年志愿者的步行稳定性,为更全面评估人体的动态平衡、预测跌倒风险提供重要依据。方法应用VICON运动捕捉系统,采集肌骨系统健康志愿者(7名老年和10名青年)在不同步速(80%、100%1、20%自然步速)下的运动学数据,提取志愿者在30个连续步态周期中,第7颈椎和第10胸椎在前后和左右方向上的位移,以及下肢各关节屈曲伸展和外展内收运动角度,计算位移和运动角度变化的最大Lyapunov指数,比较分析老年与青年组之间步行稳定性差异,以及步速对人体步行稳定性影响。结果青年组步行稳定性优于老年组,并在某些运动节段呈现显著性差异(P<0.01);老年和青年的步行稳定性随步速增加而降低(P<0.05)。结论应用非线性时间序列分析方法中的最大Lyapunov指数,能有效并定量地评测人体步行中各运动节段的稳定性。     

双任务介入对社区脑卒中患者步态参数及其对称性的影响

目的 对比社区脑卒中患者单任务步行与不同类型和不同负荷双任务步行时步态参数及其对称性的差异。方法 利用 Simi Motion 三维动作分析系统采集 20 名处于慢性恢复期的社区脑卒中患者在单任务步行及不同负荷认知双任务步行和运动双任务步行时步态参数,并间接计算出其对称指数。 采用单因素重复测量方差分析对比单任务步行与不同双任务步行时步态参数及其对称性差异。 结果 与单任务步行相比,社区脑卒中患者在高低负荷认知任务介入时步速、患侧步长、健侧摆动相占比均降低,困难认知任务介入时健侧步宽和健侧、患侧支撑相占增加、健侧步长和患侧摆动相占比降低,摆动相占比对称指数减小(P<0. 05)。 结论 社区脑卒中患者主要通过降低步速、缩减步长、降低摆动相占比、增加步宽和支撑相占比,改变步态模式来应对认知任务干扰,对于步态稳定性,高负荷认知任务的介入,会增加社区脑卒中患者摆动相占比的不对称性程度,降低其步态稳定性。     

Effects of bilateral subthalamic stimulation on gait kinematics and kinetics in Parkinson’s disease

Subthalamic nucleus (STN) stimulation, a recent surgical approach to Parkinsons disease (PD), has been shown to be effective in relieving motor symptoms. The present study carried out a full body gait analysis, during overground walking, on ten PD patients with bilaterally implanted STN stimulation devices. Walking performance was analyzed on the same day, in four conditions (Stim Off–Med Off, Stim On–Med Off, Stim Off–Med On, Stim On–Med On). The results showed that, on average, STN stimulation alone (S+M–) and l -dopa alone (S-M+), significantly increased gait speed, stride length and the lower limb joint Range of Motion (ROM) with respect to the basal condition (S–M–); also cadence was found to play a role in velocity increase, particularly when l -dopa was administered. Both treatments improved pelvis and trunk kinematics, and power production at the ankle and hip joints. The combination of the two treatments (S+M+) produced an additional effect on gait speed, stride length, ROM of knee and ankle joints, pelvis obliquity and trunk inclination. Given the additive and synergistic effects, it can be hypothesized that the two treatments have different mechanisms of action. Our results confirm the findings of earlier studies that employed treadmill walking.     

Spinal balance failure: a potential cause of spinal ligament ossification

Ossification of the posterior longitudinal ligament (OPLL) and of the ligamentum flavum (OLF), as well as calcification of ligamentum nuchae in the cervical spine and ossification of ligamentum flavum in the thoracic spine, are common types of spinal ligament ossification. As is known, the pathogenesis of OPLL and OLF has been unclear until recently, and mechanical stress assumably plays an important role. In this paper, we try to make a hypothesis that spinal balance failure (characterized by the gravity line, spinal curvature and flexion/extension in the sagittal plane), may play more important roles than any other factors in the development of ligament ossified diseases. Moreover, different stress thresholds and flexion/extension frequency may induce various ossification regions. It is supported by the conclusions that drawn from literature review: (1) OPLL and OLF seldom occur in lumbar spine which is of stiffer and lower-frequency motion than cervical spine, although its range of motion (ROM) was relatively great. (2) Spinal ligament ossification often appears in the cervical spine, which is significantly flexible with a larger motion range. (3) OLF is often seen in the thoracic spine, which is farthest away from the gravity line for thoracic kyphosis. (4) Many OPLL or OLF patients are often found with a local kyphosis or high segmental ROM. (5) The prevalence of ossification is higher in the larger stress regions, as described above, indicating that there may be a stress threshold for the spinal ligaments.