A regression-based 3-D shoulder rhythm

In biomechanical modeling of the shoulder, it is important to know the orientation of each bone in the shoulder girdle when estimating the loads on each musculoskeletal element. However, because of the soft tissue overlying the bones, it is difficult to accurately derive the orientation of the clavicle and scapula using surface markers during dynamic movement. The purpose of this study is to develop two regression models which predict the orientation of the clavicle and the scapula. The first regression model uses humerus orientation and individual factors such as age, gender, and anthropometry data as the predictors. The second regression model includes only the humerus orientation as the predictor. Thirty-eight participants performed 118 static postures covering the volume of the right hand reach. The orientation of the thorax, clavicle, scapula and humerus were measured with a motion tracking system. Regression analysis was performed on the Euler angles decomposed from the orientation of each bone from 26 randomly selected participants. The regression models were then validated with the remaining 12 participants. The results indicate that for the first model, the r² of the predicted orientation of the clavicle and the scapula ranged between 0.31 and 0.65, and the RMSE obtained from the validation dataset ranged from 6.92° to 10.39°. For the second model, the r² ranged between 0.19 and 0.57, and the RMSE obtained from the validation dataset ranged from 6.62° and 11.13°. The derived regression-based shoulder rhythm could be useful in future biomechanical modeling of the shoulder.     

Does the examiner's experience matter in evaluation of the kinematics of the upper limb?

This study aimed to evaluate test and retest reliability according to examiner experience with the three-dimensional kinematics of the trunk, scapula, and arm segments during flexion and unilateral abduction of the arm. Ten men and 10 women (mean age, 25.1 [1.1] years) participated in this study. Each volunteer participated in six test sessions, four on the first day (two for each examiner) and two on the second day (one for each examiner). A 48-h interval was given between test days. The assessments were made by one examiner with movement analysis experience and a second examiner without experience. For each session (intra-day), the volunteers performed five repetitions of unilateral arm flexions and abductions using their dominant arms. After 1 h, the data were re-collected and all markers were replaced. Data from the trunk, scapula, and arm were analysed at 30°, 60°, 90°, and 120° of arm flexion and abduction using intraclass coefficient correlation, standard error of the measurement, and analysis of variance. The results did not differ between the experienced and inexperienced examiners except for trunk axial rotation at all studied angles and for arm rotation at 120° of abduction. The examiner previously trained in movement analysis marker placement demonstrated the same intra-tester reliability as the inexperienced tester when marker placement accuracy was the variable of interest.     

特发性脊柱侧弯鼠类模型的研究现状

特发性脊柱侧弯是一种严重影响青少年身心健康的脊柱畸形,其病因和发病机制至今不明,部分原因是缺乏合适的建模系统,其中鼠类因其易感性且与人类基因高度相似,而被大量用于建立脊柱侧弯模型。本文讨论了多种建模方法,包括杂交形成脊柱侧弯大鼠、双足大鼠模型、增强瘦素活性诱导模型、雌激素诱导模型、降低体内褪黑素含量以诱导模型、基因修改和无创实验模型诱导脊柱侧凸。这些模型揭示了遗传因素、激素水平和生物力学因素在脊柱侧弯发展中的作用。尽管动物模型无法完全复制人体脊柱,存在局限性,但它们有助于研究脊柱侧弯的发病机制、进展并为未来治疗提供了重要工具,对早期诊断和干预策略的发展具有重要意义。在此,我们总结了鼠类脊柱侧弯模型的发展现状,讨论了其优缺点,并展望了其应用前景。     

Influences of limb proportions and body size on locomotor kinematics in terrestrial primates and fossil hominins

During locomotion, mammalian limb postures are influenced by many factors including the animal's limb length and body mass. Polk (2002) compared the gait of similar-sized cercopithecine monkeys that differed limb proportions and found that longer-limbed monkeys usually adopt more extended joint postures than shorter-limbed monkeys in order to moderate their joint moments. Studies of primates as well as non-primate mammals that vary in body mass have demonstrated that larger animals use more extended limb postures than smaller animals. Such extended postures in larger animals increase the extensor muscle mechanical advantage and allow postures to be maintained with relatively less muscular effort (Polk, 2002; Biewener 1989). The results of these previous studies are used here to address two anthropological questions. The first concerns the postural effects of body mass and limb proportion differences between australopithecines and members of the genus Homo. That is, H. erectus and later hominins all have larger body mass and longer legs than australopithecines, and these anatomical differences suggest that Homo probably used more extended postures and probably required relatively less muscular force to resist gravity than the smaller and shorter-limbed australopithecines. The second question investigates how animals with similar size but different limb proportions differ in locomotor performance. The effects of limb proportions on gait are relevant to inferring postural and locomotor differences between Neanderthals and modern Homo sapiens which differ in their crural indices and relative limb length. This study demonstrates that primates with relatively long limbs achieve higher walking speeds while using lower stride frequencies and lower angular excursions than shorter-limbed monkeys, and these kinematic differences may allow longer-limbed taxa to locomote more efficiently than shorter-limbed species of similar mass. Such differences may also have characterized the gait of Homo sapiens in comparison to Neanderthals, but more experimental data on humans that vary in limb proportions are necessary in order to evaluate this question more thoroughly.     

中国人肩胛骨的观察

对西安地区收集的202副(男115,女87)中国成年人肩胛骨进行了观察。中国人肩胛冈可分五型,肩胛骨脊柱缘的形状与种族和性别有关。     

肩胛骨性别的判别分析

就青岛出土已知性别成年肩胛骨84例(男66,女18)进行了12项测量,从中挑选出肩胛形态宽(X1),肩胛宽(X2),肩胛冈长(X3)和关节盂长(X4)四个变量,按Fisher法进行判别分析,其中有五种组合方式其判别率均在92.9％以上,而X3与X4两因素判别率最优,高达97.62％。此法简便,准确,具有较高的实用价值。     

多层螺旋 最大C强度投影测量肩脚孟斜倾角的价值

目的:探讨多层螺旋CT(MSCT)最大强度投影(MIP)测量肩胛孟斜倾角的价值。方法:收集成人肩关节标本24侧,用16层螺旋CT扫描仪扫描,MIP测量肩胛孟斜倾角。取MIP重建肩胛骨前后两种冠状位层面,测得两组肩胛盂斜倾角度数,进行统计学处理。结果:肩胛盂斜倾角最小值95．86°,最大值117．78°,两组肩胛盂斜倾角数据分别为106．91°±6．30°,106．60°±6．57°,两种层面肩胛盂斜倾角统计学上无显著性差异。结论:多层螺旋CT最大强度投影测量肩胛孟斜倾角层面选择对测值没有影响;多层螺旋CT MIP测量肩胛盂倾斜角具有较好的可重复性、具有重要价值。     

Musculoskeletal scapular correlates of plantigrade and acrobatic positional activities in Papio cynocephalus anubis and Macaca fascicularis

This study investigates several musculoskeletal scapular correlates of quadrupedal behavior in predominantly plantigrade, Papio cynocephalus anubis and acrobatic, less plantigrade, Macaca fascicularis. Positional behaviors differ in these two primates reflecting the amount of time spent emphasizing one or the other of these captive behavioral regimes. Stresses associated with particular patterns of behavior result in different scapular morphologies. Papio exhibits a significantly broader scapula with a more dorsoventrally curved blade accompanying an enlarged teres major muscle. The supraspinous fossa is wider in Papio, while the infraspinous/teres major attachment is wider in Macaca. Angular measurements reflect the breadth dimension of the various fossae. These results utilize two species of primates to extend a methodology developed in previous studies and to suggest that a predictable interdependence occurs between scapular dimensions and certain behavioral activities.     

Fossil platyrrhine forelimb bones from the early miocene of Argentina

Primate scapula and ulna fragments of uncertain taxonomic affinity (MACN-SC 101) have been recovered from the Pinturas deposits at Arroyo Feo, Santa Cruz, Argentina in association with Santacrucian (Early Miocene) land mammals. Least-squares regression of body weight on surface area and on height of the glenoid fossa of the scapula indicates an estimated mean weight of 3.6 kg for this individual. On the basis of qualitative and several metric features, the fossil scapula and ulna most closely resemble living platyrrhine monkeys. In estimated body weight and relative height of the coronoid process, the fossil is similar to arboreal quadrupeds, such as Cebus apella and Chiropotes. However, spinoglenoid, axilloglenoid, and axillospinal angles, length of lever arm, and length and breadth of the sigmoid notch imply behavioral similarity with larger species that also use their forelimbs extensively in climbing, such as Alouatta and Lagothrix. MACN-SC 101 may represent the incipient divergence of a generalized platyrrhine arboreal quadruped toward a more suspensory form.     

Altered activity of the serratus anterior during unilateral arm elevation in patients with cervical disorders

Altered activity in the axioscapular muscles is considered to be an important feature in patients with neck pain. The activity of the serratus anterior (SA) and trapezius muscles during arm elevation has not been investigated in these patients. The objectives of this study was to investigate whether there is a pattern of altered activity in the SA and trapezius in patients with insidious onset neck pain (IONP) (n = 22) and whiplash associated disorders (WAD) (n = 27). An asymptomatic group was selected for baseline measurements (n = 23).Surface electromyography was used to measure the onset of muscle activation and duration of muscle activity of the SA as well as the upper, middle, and lower trapezius during unilateral arm elevation in the three subject groups. Both arms were tested.With no interaction, the main effect for the onset of muscle activation and duration of muscle activity for serratus anterior was statistically significant among the groups. Post hoc comparison revealed a significantly delayed onset of muscle activation and less duration of muscle activity in the IONP group, and in the WAD group compared to the asymptomatic group. There were no group main effects or interaction effects for upper, middle and lower trapezius.This finding may have implications for scapular stability in these patients because the altered activity in the SA may reflect inconsistent or poorly coordinated muscle activation that may reduce the quality of neuromuscular performance and induce an increased load on the cervical and the thoracic spine.     

Effect of sitting postures and shoulder position on the cervicocephalic kinesthesia in healthy young males

Information about head orientation, position, and movement with respect to the trunk relies on the visual, vestibular, extensive muscular, and articular proprioceptive system of the neck. Various factors can affect proprioception since it is the function of afferent integration, and tuning of muscular and articular receptors. Pain, muscle fatigue, and joint position have been shown to affect proprioceptive capacity. Thus, it can be speculated that changes in body posture can alter the neck proprioception. This study was undertaken to investigate the effect of body posture on cervicocephalic kinesthetic sense in healthy subjects. Cervicocephalic kinesthetic sensibility was measured by the kinesthetic sensibility test in healthy young adults while in (a) habitual slouched sitting position with arms hanging by the side (SS), (b) habitual slouched sitting position with arms unloaded (supported) (SS-AS), and (c) upright sitting position with arms hanging by the side (US) during maximum and 30 degree right, left rotations, flexion, and extension. Thirty healthy male adults (mean age 27.83; SD 3.41) volunteered for this study. The least mean error was found for the SS-AS position (0.48; SD 0.24), followed by SS (0.60; SD 0.43) and US (0.96; SD 0.71), respectively. For all test conditions, there was significant difference in mean absolute error while head repositioning from maximum and 30 degree rotation during SS and SS-AS positions (p?相似文献   

The awakening cortisol response: no evidence for an influence of body posture

It has recently been reported that the orthostatic challenge associated with postural change from sitting to an upright position is stimulatory to the hypothalamic-pituitary-adrenal axis as evidenced by increased salivary free cortisol. This stimulatory influence is potentially a confound for the many psychoneuroendocrine studies for which salivary free cortisol is the main dependent variable. This particularly relates to laboratory psychosocial stress procedures in which subjects are invited to stand in order to deliver public speech and the studies which have explored the cortisol response to awakening in which postural shift has not been controlled for. We therefore examined, in a balanced cross over design whether the awakening cortisol response was influenced by standing, shortly after awakening or remaining supine during the response study period. In addition and in the same subjects we measured the cardiovascular response and saliva cortisol response to the orthostatic challenge of shifting from a supine to a standing position later in the diurnal cortisol cycle. The expected cortisol response to awakening was demonstrated but there was no evidence that the postural shift, supine to standing, confounded the response. This same postural shift later in the day induced the expected increase in heart rate but cortisol simply followed the circadian decline. Under the conditions of the present study we found no evidence that the postural shift supine to standing could induce a cortisol secretory episode such as to contribute towards the awakening response.