The functional anatomy of the human anterior talofibular ligament in relation to ankle sprains

The anterior talofibular ligament is the most commonly injured ligament in the ankle. Despite considerable interest in the clinical outcome of treatment protocols, we do not know whether the distinctive pattern of localization of the injuries relates to regional differences in the structure and molecular composition of the ligament. To address this issue, ligaments were examined by histology and immunohistochemistry. Differences in the structure of its two attachments (i.e. entheses) were evaluated with quantitative, morphometric techniques, and regional differences in the distribution of collagens, glycosaminoglycans and proteoglycans were determined qualitatively by immunolabelling. Morphometric analyses showed that bone density was less at the fibular attachment, but that enthesis fibrocartilage was more prominent. Immunohistochemistry revealed the presence of a fibrocartilage (containing type II collagen and aggrecan) at the site where the ligament wraps around the lateral talar articular cartilage in a plantarflexed and inverted foot: the fibrocartilage is regarded as an adaptation to resisting compression. We propose that avulsion fractures are less common at the talar end of the ligament because (1) bone density is greater here than at the fibular enthesis, and (2) stress is dissipated away from the talar enthesis by the 'wrap-around' fibrocartilaginous character of the ligament near the talar articular facet.     

The effect of foot arch on plantar pressure distribution during standing

Abstract

The aim of this study was to explore how foot type affects plantar pressure distribution during standing. In this study, 32 healthy subjects voluntarily participated and the subject feet were classified as: normal feet (n?=?23), flat feet (n?=?14) and high arch feet (n?=?27) according to arch index (AI) values obtained from foot pressure intensity image analysis. Foot pressure intensity images were acquired by a pedopowergraph system to obtain a foot pressure distribution parameter-power ratio (PR) during standing in eight different regions of the foot. Contact area and mean PR were analysed in hind foot, mid-foot and fore foot regions. One-way analysis of variance was used to determine statistical differences between groups. The contact area and mean PR value beneath the mid-foot was significantly increased in the low arch foot when compared to the normal arch foot and high arch foot (p?<?0.001) in both feet. However, subjects with low-arch feet had significantly higher body mass index (BMI) compared to subjects with high-arch feet (p?<?0.05) and subjects with normal arch feet (p?<?0.05) in both feet. In addition, subjects with low-arch feet had significant differences in arch index (AI) value as compared to subjects with high-arch feet (p?<?0.001) and subjects with normal arch feet (p?<?0.05) in both feet. Mean mid-foot PR value were positively (r?=?0.54) correlated with increased arch index (AI) value. A significant (p?<?0.05) change was obtained in PR value beneath the mid-foot of low arch feet when compared with other groups in both feet. The findings suggest that there is an increased mid-foot PR value in the low arch foot as compared to the normal arch foot and high arch foot during standing. Therefore, individuals with low arch feet could be at high risk for mid-foot collapse and Charcot foot problems, indicating that foot type should be assessed when determining an individual’s risk for foot injury.     

背向行走足底压力分布特征对平衡能力的影响

目的研究背向行走过程中足底压力的变化,从而探究其对人体步态平衡能力的影响。方法使用足底压力测量系统(Pedar-X压力鞋垫)采集10名受试者在正向和背向两种行走模式下的足底压力数据。试验在跑步机上进行,以正向行走作为对照试验组。依据试验条件及预试验时受试者的直观感受,选取4个速度(2.0、2.5、3.0、3.5 km/h)分别进行两种行走模式下的试验,分析不同速度下足底压力中心轨迹、足底压力、足-地接触时间等参数的变化情况。结果不同速度的两种行走模式下,人在行走过程中的足底压力有所不同。背向行走过程中,足底压力中心从足前部向足跟过渡,从内侧向外侧过渡。相比正向行走,背向行走时的足底压力显著减小,行走过程中的足-地接触时间有所增加。结论研究背向行走的压力分布有助于更全面地理解人的动态平衡机制,并为行走稳定性的相关研究提供新视角。     

The influence of vision on the automatic postural muscle responses of newly standing and newly walking infants

In adults, visual inputs do not appear to contribute significantly to automatic postural muscle responses (90–100 ms latency) activated by transient support surface displacements causing threats to standing balance, but are activated through slow pathways with latencies of more than 200 ms. However, it has been shown that the postural sway behavior of early walking infants is strongly influenced by visual flow cues that falsely signal self-movement. To determine whether there also are significant contributions of vision to automatic postural muscle responses in this age group, two groups of infants were tested on a moveable platform; pre-walkers (n=6) and early walkers (n=6). Pre-walkers did not show any measurable effect of visual condition (vision vs no vision) on muscle response characteristics. However, the integrated gastrocnemius activity of early walkers increased significantly in vision versus no vision conditions (P<0.05). These results show that visual cues contribute to, or modulate, the automatic postural responses in children who are in the developmental transition to independent walking. Received: 10 May 1996 / Accepted: 23 January 1998     

Involvement of the head and trunk during gaze reorientation during standing and treadmill walking

As individuals stand or walk in an environment their gaze may be reoriented from one location to another in response to auditory or visual stimuli. In order to reorient gaze, the eyes and/or the head and trunk must rotate. However, what determines the exact degree of rotation of each segment while standing or walking is not fully understood. In the current study we show that when participants were asked to reorient their gaze towards light cues positioned at eccentric locations of up to 90° while standing or walking on a treadmill their eyes and head mainly facilitated the action. Rotations of the head-in-space were similar for both tasks, but the rotation of the shoulders- and hips-in-space were lower for the treadmill walking condition. It is argued that this difference in the level of head-on-trunk rotation during the two tasks is controlled by the vestibular feedback loop. The regulation of this feedback loop is performed by the cerebellum in response to the level of threat to postural stability.     

前交叉韧带侧向刚度在线测量系统研制及其对前交叉韧带重建效果的影响

前交叉韧带重建张力的设置主要依靠外科医生的经验。为提高膝关节恢复治疗中前交叉韧带重建后张力的有效性和适应性,本文建立具有松弛特性的侧向力学测量模型,设计前交叉韧带在线刚度测量系统,提出"术前检测,术中参考"的新方法。本文选取20个绵羊膝关节进行膝关节稳定性测试,分两组进行前外侧入路单束前交叉韧带重建对比实验,第一组手术医生常规流程进行术中检测;第二组使用前交叉韧带在线刚度测量系统在术中进行检测;之后对上述两组进行术后稳定性实验。研究结果表明,该测量系统测量的张力精度为(-2.3±0.04)%,位移误差为(1.5±1.8)%,术后对两组进行前向稳定性、内旋稳定性和外旋稳定性测试,结果均优于术前(P <0.05),但使用该系统的一组更接近术前膝关节测量指标,且与经验丰富的医生对比差异无统计学意义(P> 0.05)。最终,期待本文建立的该系统可以帮助临床医生判断手术过程中的前交叉韧带重建张力,有效提升手术效果。     

正畸力作用下上颌尖牙牙周膜的应力应变分布

背景：口腔临床工作者可以根据牙周膜应力分布控制正畸施力的方式和大小,从而优化正畸力系统设计。 目的：分析正畸力载荷作用下牙周膜的应力应变分布。 方法：将上颌尖牙牙根近似为抛物线形柱体模型,分析上颌尖牙牙根在正畸力作用下牙周膜应力应变分布。对模型加载、求解,对近似模型在剪力、轴力、弯矩以及扭矩分别作用下牙周膜应力应变分布进行分析,并将计算结果应用到正畸力作用下牙周膜应力应变分析。 结果与结论：实验结果显示有限元分析和理论计算结果差别较小,最大为13.4%,并且高应力区出现在牙槽嵴顶部截面。正畸力作用下牙周膜中应力应变分布比较复杂,应力应变分布不仅与牙根长度,还与不同的加载力系统有关。因此临床治疗过程中,口腔医生应适当地考虑这些因素。 关键词：牙周膜;正畸力;应力应变分布;上颌尖牙;生物力学 doi:10.3969/j.issn.1673-8225.2012.13.009     

篮球鞋对主动与被动落地时冲击力特征和肌肉活化的影响

目的探讨人体在主动和被动落地过程中,穿着篮球鞋对落地冲击力特征和下肢相关肌群活化程度的影响。方法选取具备强缓冲性能的篮球鞋作为测试用鞋,并辅以对照鞋。12名球类专项男运动员作为受试者,在翻板器上完成包括由低到高3种下落高度和2种下落方式(主动落地反跳和被动着地)在内的着地动作。利用测力台和肌电分析系统同步采集冲击力和下肢5块主要肌群的EMG信号。结果主动落地反跳时,穿着篮球鞋并没有对冲击力的振幅和频率以及下肢肌群的激活程度产生影响;但被动着地时,穿着篮球鞋却能够显著降低冲击力和负载率的峰值,减小冲击频率(P<0.05),同时显著降低下肢各主要肌群的后激活程度(P<0.05)。结论在主动控制完成动作的情况下,运动鞋影响冲击力和肌肉活化的效果并不明显;然而当人体未完全控制着地状态时,篮球鞋能够改变输入于下肢的冲击力信号,达到缓冲避震并适当减小肌肉活化的效果,为避免落地时运动损伤的发生及机能节省化起到了积极的作用。     

Activity of pyramidal tract neurons in the cat during standing and walking on an inclined plane

To keep balance when standing or walking on a surface inclined in the roll plane, the cat modifies its body configuration so that the functional length of its right and left limbs becomes different. The aim of the present study was to assess the motor cortex participation in the generation of this left/right asymmetry. We recorded the activity of fore- and hindlimb-related pyramidal tract neurons (PTNs) during standing and walking on a treadmill. A difference in PTN activity at two tilted positions of the treadmill (± 15 deg) was considered a positional response to surface inclination. During standing, 47% of PTNs exhibited a positional response, increasing their activity with either the contra-tilt (20%) or the ipsi-tilt (27%). During walking, PTNs were modulated in the rhythm of stepping, and tilts of the supporting surface evoked positional responses in the form of changes to the magnitude of modulation in 58% of PTNs. The contra-tilt increased activity in 28% of PTNs, and ipsi-tilt increased activity in 30% of PTNs. We suggest that PTNs with positional responses contribute to the modifications of limb configuration that are necessary for adaptation to the inclined surface. By comparing the responses to tilts in individual PTNs during standing and walking, four groups of PTNs were revealed: responding in both tasks (30%); responding only during standing (16%); responding only during walking (30%); responding in none of the tasks (24%). This diversity suggests that common and separate cortical mechanisms are used for postural adaptation to tilts during standing and walking.     

Differential regulation of crossed cutaneous effects on the soleus H-reflex during standing and walking in humans

Although sensory inputs from the contralateral limb strongly modify the amplitude of the Hoffmann (H-) reflex in a static posture, it remains unknown how these inputs affect the excitability of the monosynaptic H-reflex during walking. Here, we investigated the effect of the electrical stimulation of a cutaneous (CUT) nerve innervating the skin on the dorsum of the contralateral foot on the excitability of the soleus H-reflex during standing and walking. The soleus H-reflex was conditioned by non-noxious electrical stimulation of the superficial peroneal nerve in the contralateral foot. Significant crossed facilitation of the soleus H-reflex was observed at conditioning-to-test intervals in a range of 100–130 ms while standing, without any change in the background soleus electromyographic (EMG) activity. In contrast, the amplitude of the soleus H-reflex was significantly suppressed by the contralateral CUT stimulation in the early-stance phase of walking. The background EMG activity of the soleus muscle was equivalent between standing and walking tasks and was unaffected by CUT stimulation alone. These findings suggest that the crossed CUT volleys can affect the presynaptic inhibition of the soleus Ia afferents and differentially modulate the excitability of the soleus H-reflex in a task-dependent manner during standing and walking.     

Determination of thein situ forces and force distribution within the human anterior cruciate ligament

Thein situ forces and their distribution within the human anterior cruciate ligament (ACL) can clarify this ligament's role in the knee and help to resolve controversies regarding surgical treatment of ACL deficiency. We used a universal force-moment sensor (UFS) to determine the magnitude, direction, and point of application of thein situ forces in the ACL in intact human cadaveric knees. Unlike previous studies, this approach does not require surgical intervention, the attachment of mechanical devices to or near the ACL, ora priori assumptions about the direction ofin situ force. Anterior tibial loads were applied to intact knees, which were limited to 1 degree of freedom at 30^o flexion. Thein situ forces developed in the ACL were lower than the applied force for loads under 80 N, but larger for applied loads of more than 80 N. The direction of the force vector corresponded to that of the anteromedial (AM) portion of the ACL insertion on the tibial plateau. The point of force application was located in the posterior section of the anteromedial portion of the tibial insertion site. The anterior and posterior aspects of the anteromedial portion of the ACL supported 25% and 70% of thein situ force, respectively, with the remainder carried by the posterolateral portion. We believe that the data obtained with this new UFS methodology improves our understanding of the role of the ACL in knee function, and that this methodology can be easily extended to study the function of other ligaments.     

The influence of tibial slope on the graft in combined high tibial osteotomy and anterior cruciate ligament reconstruction

Background

Young patients with severe medial osteoarthritis, varus malalignment and insufficiency of the anterior cruciate ligament (ACL) are difficult to treat. The tibial slope has gained attention with regard to osteotomies and ligamentous instability. The purpose was to evaluate the outcome of combined high tibial osteotomy (HTO), ACL reconstruction and chondral resurfacing (CR, abrasion plus microfracture), and to analyse graft failure rates with regard to the tibial slope.

Immediate effects of a rucksack type orthosis on the elderly with decreased lumbar lordosis during standing and walking

The spinal orthosis, the so-called rucksack type orthosis (RO), has been used to relieve low back pain and fatigue during prolonged standing and walking for the elderly with spinal deformities. However, little is known about the RO's kinematical effects. Twenty-three elderly (78.9 +/- 6.9 years old) participated in experiment 1, and 13 elderly (78.4 +/- 7.9 years old) in experiment 2. They had decreased lumbar lordosis or lumbar kyphosis. In experiment 1, using the "Spinal Mouse", which can measure spinal curvature, the effects of the RO on posture during standing were investigated. In experiment 2, using electromyography, the effects of the RO on muscle activity during standing and walking were clarified. Lumbar curvature and the trunk angle of inclination during standing improved significantly when the RO was used. Back extensor muscle activities (T9, L3, and L5) during standing and walking decreased significantly when the RO was used. There were no significant differences in the activities of the upper trapezius and vastus lateralis during standing and walking. The present study suggests that the elderly with lumbar deformities might be able to stand and walk more efficiently with the RO. The RO could prove to be valuable in preservation therapy for the elderly with decreased lumbar lordosis or lumbar kyphosis.     

The influence of body weight on energy expenditure during walking on a road and on a treadmill

Summary 4 oxygen consumptions were measured on 8 subjects (varying in weight from 54.4–66.1 kg) at each of 3 speeds of walking (3.2, 4.8 and 6.4 km/hr) both on a treadmill and a road. Correlations between weight and oxygen consumption of 0.76–0.96, were significant at the 0.1% level of significance, at all three speeds on both treadmill and road. The relationship between body weight and oxygen consumption is linear and is markedly affected by speed. The slope of the linear regression lines of oxygen consumption on body weight increased hyperbolically with an increase in speed. Mean oxygen consumptions at 3.2 and 4.8 km/hr were significantly higher on the road but not at 6.4 km/hr. Curves of O₂ consumption/speed are non-linear and are markedly affected by body weight; both the intercept on the vertical axis and slope increases linearly with body weight.     

The vascular and neuronal composition of the lateral ligament of the rectum and the rectosacral fascia

Summary Detailed dissections were performed on 83 pelvic halves from 45 cadavers in order to obtain more accurate data on the composition of the lateral ligament of the rectum and the rectosacral fascia. The middle rectal artery was observed in only 18 out of 81 spcimens (22.2%). The lateral ligament of the rectum was divided into lateral and medial portions, according to the positional relationship to the pelvic plexus. The lateral part consisted of a superoanterior and an inferoposterior subdivision. The main component of the former was the middle rectal artery, while the pelvic splanchnic nerves were contained in the latter. Both components can be considered to contribute to the formation of the medial part, although the middle rectal vessels were not always present. The medial part consisted of the rectal branches from the pelvic plexus and their connective tissue. The rectosacral fascia was formed by dense connective tissue between the posterior wall of the rectum and the third and fourth sacral vertebrae. The main components of the fascia were branches of the lateral and median sacral vessels and the sacral splanchnic nerves which arose directly from the sacral sympathetic ganglia.

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La structure du ligament latéral du rectum et du fascia recto sacré

Résumé La dissection de 83 hémibassins provenant de 45 cadavres a été réalisée pour préciser la structure du ligament latéral du rectum et du fascia recto sacré. L'artère rectale moyenne (ARM) a été observée seulement sur 18 specimens (22,2 %). Le ligament latéral du rectum a été divisé en portion latérale et médiale, en fonction des rapports topographiques avec le plexus pelvien. La partie latérale présente une portion antérosupérieure contenant l'ARM et une portion postéro-inférieure contenant les nerfs splanchniques pelviens (NSP). Ces deux composants (ARM et NSP) contribuent à la formation de la partie médiale bien que les vaisseaux rectaux moyens ne soient pas toujours présents. La partie médiale répond aux branches rectales du plexus pelvien et à leurs tissus conjonctifs environnants. Le fascia sacro-rectal est formé de tissu conjonctif dense, tendu de la paroi postérieure du rectum aux 3e et 4e vertèbres sacrées. Les principaux composants de ce fascia sont les branches latérales et médiales des vaisseaux sacrés et les nerfs splanchniques sacrés arrivant directement des ganglions sympathiques sacrés.

     

Effect of wearing a knee brace or sleeve on the knee joint and anterior cruciate ligament force during drop jumps: A clinical intervention study

Background

Knee braces are considered to be extremely useful tools in reducing the shear force of knee joints for non-contact anterior cruciate ligament (ACL) injury prevention. However, the effectiveness of sports knee braces and sleeves remains to be identified. Therefore, the purpose of this study was to evaluate the effectiveness of wearing commercialized sports knee braces and sleeves on knee kinematics, kinetics, and ACL force during drop jumps using musculoskeletal modeling analysis.

Evaluation of the walking pattern in two types of patients with anterior cruciate ligament deficiency: copers and non-copers

The purpose of the present study was to investigate whether different walking patterns in healthy subjects and in coper and non-coper subjects with deficient anterior cruciate ligaments could be quantified. An inverse dynamics approach was used to calculate joint kinematics and kinetics for flexion and extension. EMG signals of the hamstrings and quadriceps muscles were recorded. The results showed that the peak knee flexion angle was greater in the copers than in the controls. There was a positive correlation between the peak knee extensor moment and peak knee flexion angle. Furthermore, at a given peak knee flexion angle, the peak knee extensor moment was significantly larger in the controls than in the non-copers. The hip extensor moment in the copers was significantly larger than that of the non-copers and the controls. In conclusion, the three groups walked according to different patterns. It is suggested that the copers stabilized their knee joint by co-contraction of the hamstrings and quadriceps muscles, while the non-copers lacked this ability. Instead, the non-copers reduced the knee extensor moment in order to decrease anterior displacement of the tibia. The walking pattern differences observed between the copers and non-copers may explain their different post-injury activity levels. Electronic Publication