Skeletal evidence for kneeling in prehistoric Ecuador.

Bony changes on the superior distal surface of the metatarsals and the superior proximal surface of the first proximal foot phalanx are described in a prehistoric skeletal sample from Coastal Ecuador. The location and morphology of the alterations, as well as their association with femoral "squatting facets" strongly suggests they were produced by prolonged hyperdorsiflexion of the toes, probably resulting from habitual kneeling posture. Comparative data are presented from five other New World skeletal samples.     

Incidence of squatting facets on the talus of Indians (Agra region).

230 adult Indian tali (from Agra region) were studied for the incidence of squatting facets. Extension of medial articular facet was observed in all the cases. Medial extension of trochlea was observed in 37% of cases; lateral extension of trochlea in 71.6% of cases, lateral squatting facets in 43.5% of cases and medial squatting in 8.6% of cases. The present data are compared with that of other workers.     

Analysis of a new polycentric above-knee prosthesis with a pneumatic swing phase control

The four-bar linkage mechanism used by many designers for the knee joint of an above-knee prosthesis can provide knee rotation suitable for walking only. In Afro-Asian countries people are habituated to the squatting posture in their daily activities. A six-bar linkage knee-ankle mechanism above-knee prosthesis with a pneumatic swing phase control is developed and its analysis shows its suitability for producing a motion closely resembling that of a normal subject during walking and squatting.     

Squatting facet: a case study Dilkaya and Van-Kalesi populations in eastern Turkey

Anomalies of the skeleton provide information on living conditions, cultural structure and health problems in ancient societies. Squatting facet is a kind of anomaly that forms on the surfaces where the tibia and talus articulate is the squatting facet states the daily activities and living style of the society. The aim of this study is to learn the daily activities of the medieval societies in the Van region through studying of squatting facets. In this study, adult skeletons from Dilkaya and Van Kalesi-Eski Van Sehri societies dating to the Medieval Age were investigated (65 tibia and 82 tali from Dilkaya, 61 tibia and 52 tali from Van Kalesi-Eski Van Sehri). The lateral squatting facet had high ratios in both societies. The tibia lateral squatting facet found on females and males of Dilkaya was 97.2% and 96.9%, respectively, and on females and males of Van kalesi Eski Van Sehri was 87.5% and 89.2%, respectively. The talus lateral squatting facet found on females and males of Dilkaya was 72.1% and 51.3%, respectively, and on females and males of Van kalesi Eski Van Sehri was 91.2% and 83.7%, respectively. The results provide an opportunity to study the relationship between past and modern population, and also describe the daily activity of life and cultural structure.     

The relation between the changes of postural achievement, lower limb muscle activities, and balance stability in three different deep-squatting postures

Deep squatting places a burden on the lower limb muscles and influences postural balance. We attempted to determine the effects of postural changes on the rectus femoris, tibialis anterior, gastrocnemius, soleus, and extensor digitorum brevis muscles during squatting in 8 healthy male subjects. Three squatting conditions were involved: full squatting (FS), tiptoe squatting (TT), and tiptoe squatting on a 15 degrees slope (TTS), performed randomly and recorded in a period of 4 min for each task. The influence of the squatting condition on electromyography and vertical ground reaction force parameters was examined in order to observe the effect of postural alteration on muscle activity and balance control. The results showed that the change of squatting posture from FS to TT decreased the activity of the rectus femoris and tibialis anterior muscles. FS has been suspected as a main cause of musculoskeletal complaint during prolonged squatting. In contrast, as the heel was lifted, the extensor digitorum brevis muscle increased to 39% of maximum activation. On the other hand, sway analysis at TT showed balance instability regarding the large area occupation of the center of pressure displacement. The presence of a 15 degrees slope significantly reduced the muscular load. This simple study suggests that the inclusion of a sloping surface in daily activities that requires a squatting posture would be an effective means to reduce muscular load.     

The evaluation of the effect of stool height alteration on workload of squatting postures performed by Indonesians with different body mass index (BMI)

Indonesians commonly perform activities on the floor that require squatting postures. It has been identified that adopting squatting postures without any proper support would gradually cause postural stress. This study examines the influence of different squatting heights to the body kinematics and subjective discomfort rating. The subjects were divided into two different body types: overweight subjects with BMI > 24.9 and normal weight subjects with BMI 18-24.9. The subjects adopted a squatting posture at no-stool condition and at the stool height of 10, 15, and 20 cm. The task was to simulate the work close to the ground level with the hip joint deeply flexed. Body segmental angular flexion (SAF) and the visual analog scale (VAS) method were selected for parameter analyses. Significant differences were found in both parameters SAF (trunk, hip, knee, and ankle) and VAS. The interaction effect was found by squatting height and the body type for SAF of the trunk (p < 0.05). However, the increasing BMI index was also found significantly affected associated with the anthropometrical characteristics for buttock height and lower limbs depth. It is suggested that normal weight subjects sit comfortably at 15 cm stool height, whereas overweight subjects preferred 20 cm stool height as a better acceptability condition in terms of overall parameter analyses.     

The influence of different lower seat height on the muscular stress during squatting for a ground level job

Work requiring extremely body flexion is strongly associated with a high incidence of musculoskeletal injuries often reported during adopting squatting. In this study, the influence of different lower seat heights on the muscular stress in squatting on a stool (SS) were examined in comparison with fully squatting (FS). Fourteen healthy Indonesian males were recruited in the experiment. Two-dimensional body kinematics, ground reaction force (GRF) and electromyography (EMG) data were collected as subjects performed forward movement under four squatting height conditions which were FS and SS at 10 cm, 15 cm and 20 cm seat height. The results demonstrated that the change from FS to SS primarily affected the segmental angular flexions and muscular activities in the upper and lower limbs. GRF data showed that the SS conditions delivered 24% body weight onto the seat. The change of FS to SS showed significantly decrease in muscular load of the rectus femoris and tibialis anterior. In contrast, the soleus and gastrocnemius increased the activities as the seat height increased. The type of task that required the hand to handle the object on the ground level affected the trunk to be more flexed as the seat height increased. The findings of this study suggest that the use of a lower seat stool of a proper height seems to be a sub-optimal solution considering the change of muscular load associated with the discomfort in a squatting posture.     

Models of the geometry of the human ankle bone pulley: two series of geometric models for demonstrating the biomechanics of the ankle joint

2 series of models demonstrate the geometrical shape of the human trochlea tali. We have changed step by step the shape of the 2 flanking articular facets of the trochlea, the course of the edges of the trochlea, and the length of their radii, and so we have found a model responding to the biomechanic conditions of the trochlea tali. The convex surface of this model (corresponding to the superior articular surface, i.e. the facies superior trochleae tali) is a torse, the medial flanking facet (corresponding to the medial articular facet of the trochlea, i.e. the facies malleolaris medialis) is a flat cone, the lateral flanking facet (corresponding to the lateral articular facet of the trochlea, i.e. the facies malleolaris lateralis) is a screwed (helicoidal) face. The resulting model shows the 2 completely different phases of motion in the ankle joint: During dorsiflexion (motion setting out from the neutral position towards the final position of dorsiflexion), the internal malleolus leads the talus, whereas the external malleolus is pushed outwards by the screwed lateral articular facet of the trocheal. The trochlea is moved like a hinge. In the final position of dorsiflexion, the malleoli tightly embrace the 2 flanking facets of the trochlea, whilst an obvious cleft appears dorsally and medially between the superior articular surface of the trochlea and the tibial roof (i.e. the facies articularis inferior tibiae). During plantarflexion (motion setting out from the neutral position towards the final position of plantarflexion), the external malleolus leads the talus, whereas the medial articular facet of the trochlea withdraws from the internal malleolus. The trochlea is moved like a screw. In the final position of plantarflexion, the superior articular surface of the trochlea closely contacts the tibial roof, whilst an obvious cleft appears between the medial articular facet of the trochlea and the internal malleolus.     

Tibio-femoral movement in the living knee. A study of weight bearing and non-weight bearing knee kinematics using 'interventional' MRI

The aim of this study was to image tibio-femoral movement during flexion in the living knee. Ten loaded male Caucasian knees were initially studied using MRI, and the relative tibio-femoral motions, through the full flexion arc in neutral tibial rotation, were measured. On knee flexion from hyperextension to 120 degrees , the lateral femoral condyle moved posteriorly 22 mm. From 120 degrees to full squatting there was another 10 mm of posterior translation, with the lateral femoral condyle appearing almost to sublux posteriorly. The medial femoral condyle demonstrated minimal posterior translation until 120 degrees . Thereafter, it moved 9 mm posteriorly to lie on the superior surface of the medial meniscal posterior horn. Thus, during flexion of the knee to 120 degrees , the femur rotated externally through an angle of 20 degrees . However, on flexion beyond 120 degrees , both femoral condyles moved posteriorly to a similar degree. The second part of this study investigated the effect of gender, side, load and longitudinal rotation. The pattern of relative tibio-femoral movement during knee flexion appears to be independent of gender and side. Femoral external rotation (or tibial internal rotation) occurs with knee flexion under loaded and unloaded conditions, but the magnitude of rotation is greater and occurs earlier on weight bearing. With flexion plus tibial internal rotation, the pattern of movement follows that in neutral. With flexion in tibial external rotation, the lateral femoral condyle adopts a more anterior position relative to the tibia and, particularly in the non-weight bearing knee, much of the femoral external rotation that occurs with flexion is reversed.     

Throwing in the Middle and Upper Paleolithic: inferences from an analysis of humeral retroversion

When in evolutionary history did long-range projectile weapons become an important component of hunting toolkits? The archeological evidence for the development of projectile weaponry is complex and generally indirect, and has led to different conclusions about the origin and spread of this technology. Lithic evidence from the Middle Stone Age (MSA) has led some researchers to suggest that true long- range projectile weaponry developed in Africa perhaps as early as 80,000 years ago, and was part of the subsistence toolkit carried by modern humans who expanded out of Africa after 50,000 years ago. Alternatively, temporal patterns in the morphology of pointed lithics has led others to posit an independent, convergent origin of projectile weaponry in Africa, the Near East, and Europe during the interval between 50,000-40,000 years ago. By either scenario, projectile weapons would not have been a component of the hunting arsenal of Neandertals, but may have been in use by European early modern humans and thus, projectile technology may have entered into the competitive dynamics that existed between these two groups. The origins of projectile weapons can be addressed, in part, through analyses of the skeletal remains of the prehistoric humans who made and used them. Habitual behavior patterns—including those related to the production and use of technology—can be imprinted on the skeleton through both genetic and epigenetic pathways. Recent studies in the field of sports medicine indicate that individuals who engage in habitual throwing have increased humeral retroversion angles in their throwing arms and a greater degree of bilateral asymmetry in retroversion angles than do non-throwers. This contribution investigates humeral torsion through analysis of the retroversion angle in samples of Eurasian Neandertals, European early modern humans of the middle and late Upper Paleolithic, and comparative samples of recent humans. This analysis was conducted under the assumption that if throwing-based projectile weaponry was used by early modern Europeans but not Neandertals, Upper Paleolithic samples should be similar to recent human groups engaged in habitual throwing in the degree of humeral retroversion in the dominant limb and in bilateral asymmetry in this feature. Neandertals on the other hand, would not be expected to show marked asymmetry in humeral retroversion. Consistent with other studies, Neandertals exhibit increased retroversion angles (decreased humeral torsion or a more posteriorly oriented humeral head) relative to most modern human samples, although this appears more likely related to body form and overall activity levels than to habitual throwing. Although Neandertals with bilaterally preserved humeri sufficient for measurement are rare (consisting of only two males and one female), levels of bilateral asymmetry in humeral retroversion are low, suggesting a lack of regular throwing. While patterning across fossil and comparative samples in levels of humeral retroversion was not clear cut, males of both the middle and late Upper Paleolithic demonstrate a high level of bilateral asymmetry, comparable to or in excess of that seen in samples of throwing athletes. This may indicate habitual use of throwing-based projectile weaponry by middle Upper Paleolithic times. Small sample sizes and relatively great variance in the fossil samples makes these results, however, suggestive rather than conclusive.     

不同体位对收缩时间间期(STI)和每搏输出量(SV)的影响

用心阻抗法测算了30名男性青年学生在卧、蹲、垂直(坐、站)等不同体位状态下的收缩时间间期、每搏输出量和心输出量。结果表明,QS_2、LVET、LVETc、SY、CO均随卧、蹲、坐、站位递减;而PEP、QS_1、IVCT、PEP/LVET则按上述体位的顺序递增。本文认为,STI可反映不同体位状态下的血液动力学改变,其中LVET和PEP/LVET两个指标更为敏感。     

扫描电镜分析牙齿釉质结构方法的讨论

通过扫描电镜对大熊猫牙齿釉质结构的三维观察与比较,结果表明:在同一枚牙齿上,不同部位的釉质切面,釉柱截面的形状、大小以及排列等,有不同的现象.因此在用上述特征描述时,应对所有要比较的样品,须精确地统一在相同的部位.本文以多次实验结果,表明了严格定位取样的重要性.     

Modulation of separation distress by alpha-MSH

The effects of centrally administered alpha-MSH on separation-induced distress vocalizations (DVs) and squatting were evaluated in domestic chicks for dose-response, time course, and interactions with peripheral naloxone and both peripheral and central morphine. Some of the tests were conducted in both the presence and absence of social stimuli (mirrors or a conspecific). Doses of 0.04 microgram of alpha-MSH or greater eliminated the usual suppression of DVs produced by mirrors or conspecifics. This effect lasted 10-15 minutes and was followed by inhibition of DVs, accompanied by a dose-dependent vigilant squatting posture, that lasted about one hour. These effects showed no development of tolerance to repeated alpha-MSH injections over a six-day period, and no apparent interaction with the effects of peripherally injected naloxone or either peripherally or centrally injected morphine. It is suggested that, in keeping with its role in defensive camouflage in amphibians, alpha-MSH in chicks may activate a central state akin to fear to adaptively modulate DVs and defensive hiding.     

Experimental investigation of failure load and fracture patterns of C2 (axis).

The injury mechanism and magnitude of failure load of C2 fractures are important in the clinical treatment of its fixation. The magnitudes of the failure load of C2 and the mechanism of injury in vivo are uncertain. Accordingly, nine C2 vertebrae obtained from cadaver spines, ranging in age from 51 to 80 years, were used for the study. Special restraint conditions were applied to yield specific fracture of C2. With the posterior element potted postero-anteriorly up to one-quarter of the inferior facet, posterior shear force ranging from 840 to 1220N was required to cause fracture across the pars interarticularis. For odontoid fracture study, a special rig was fabricated to encapsulate the body of C2 in a cell using ISOPON, and a thin layer of ISOPON sandwiched between the inferior facets and two lateral plates. The assembled rig permits slight sagittal movement of C2 about the cup lateral pivot supports. Failure load of between 900 and 1500N was recorded for odontoid fracture. These values are in agreement with published data. The experiment carried out under these two different restraint conditions had specifically resulted in different fractures of C2. In reality, depending on factors such as the inclination of this force vector applied to the head, the precise posture at the time of trauma, the spinal geometry, and the physical properties, different types of fracture patterns of C2 may be produced. This additional data will be useful in the biomechanical study of C2 vertebra using analytical approaches, and in surgical anterior/posterior fixation using screws.     

Load along the tibial shaft during activities of daily living

External load at the tibia during activities of daily living provides baseline measures for the improvement of the design of the bone–implant interface for relevant internal and external prostheses. A motion analysis system was used together with an established protocol with skin markers to estimate three-dimensional forces and moments acting on ten equidistant points along the tibial shaft. Twenty young and able-bodied volunteers were analysed while performing three repetitions of the following tasks: level walking at three different speeds, in a straight-line and with sudden changes of direction to the right and to the left, stair ascending and descending, squatting, rising from a chair and sitting down. Moment and force patterns were normalised to the percentage of body weight per height and body weight, respectively, and then averaged over all subjects for each point, about the three tibial anatomical axes, and for each task. Load patterns were found to be consistent over subjects, but different among the anatomical axes, tasks and points. Generally, moments were higher in the medio/lateral axis and influenced by walking speed. In all five walking tasks and in ascending stairs with alternating feet, the more proximal the point was the smaller the mean moment was. For the remaining tasks the opposite trend was observed. The overall largest value was observed in the medio/lateral direction at the ankle centre in level walking at high speed (9.1% body weight * height on average), nearly three times larger than that of the anterior/posterior axis (2.9) during level walking with a sidestep turn. The present results should be of value also for in-vitro mechanical tests and finite element models.     

The effect of a knee support on the biomechanical response of the low back

Stooping and squatting postures are seen in a number of industries (e.g., agriculture, construction) where workers must work near ground level for extended periods of time. The focus of the current research was to evaluate a knee support device designed to reduce the biomechanical loading of these postures. Ten participants performed a series of sudden loading tasks while in a semisquat posture under two conditions of knee support (no support and fully supported) and two conditions of torso flexion (45 and 60 degrees ). A weight was released into the hands of the participants who then came to steady state while maintaining the designated posture. As they performed this task, the EMG responses of the trunk extensors (multifidus and erector spinae) were collected, both during the "sudden loading" phase of the trial as well as the steady weight-holding phase of the trial. As expected, the effects of torso flexion angle showed significant decreases in the activation of the multifidus muscles with greater torso angle (indicating the initiation of the flexion-relaxation response). Interestingly, the results showed that the knee support device had no effect on the activation levels of the sampled muscles, indicating that the loss of the degree of freedom from the ankle joint during the knee support condition had no impact on trunk extensor muscle response. The a priori concern with regard to these supports was that they would tend to focus loading on the low back and therefore would not serve as a potential ergonomic solution for these stooping/semisquatting tasks. Because the results of this study did not support this concern, further development of such an intervention is underway.     

兔后交叉韧带断裂后外侧胫骨平台退变的组织学研究

目的：探讨兔后交叉韧带（Posterior cruciate ligament,PCL）断裂对外侧胫骨平台组织学的影响。方法：48只家兔膝关节随机配对为实验侧和对照侧造模,造模后第4、8、16、24周各随机处死12只,行外侧胫骨平台大体观察、HE染色、免疫组化检测基质金属蛋白酶13（matrix metalloproteinase-13,MMP-13）、基质金属蛋白酶抑制剂1（Tisse inhibitor-1 of matrix metalloproteinasel,TIMP-1）表达。结果：①大体观察,随时间延长,实验组外侧胫骨平台软骨出现磨损,呈灰黄色,弹性差,骨赘形成。②组织学观察,随时间延长,胫骨平台软骨纤维化,细胞排列紊乱,簇聚细胞出现频率增加。⑧实验组MMP-13、TIMP—1表达均高于对照组,有显著性差异。P〈0．05。④实验组MMP-13、TIMP-1表达阳性率第4、8、16周逐渐升高,24周下降,各组比较有显著性差异,P〈0．05。结论：①兔膝关节PCL断裂会引起外侧胫骨平台软骨退行性变,且该退变随着时间的推移逐渐加重。②MMP-13与TIMP-1在PCL断裂膝关节外侧胫骨平台中的表达呈现先高后低的变化规律,造成MMP-13与T1MP-1的失衡,加速软骨退变。⑨MMP-13与T／MP-1表达增高提示MMP-13与TIMP—1可能参与了PCL断裂后外侧胫骨平台软骨的退变过程。     

Heart rate and arterial pressure variability in humans during different orthostatic load.

The influence of posture on the rhythms in blood pressure, heart rate and respiration was tested by means of spectral analysis in 14 healthy subjects. During squatting, standing and sitting, the finger blood pressure was recorded by the non-invasive Penáz technique together with cardiac intervals and respiratory movements. The power spectra obtained from five-minute samples showed that the respiratory components of cardiac interval and pulse pressure were reduced significantly in standing. Compared to squatting, a significant increase of total power in the medium frequency band (0.05-0.15 Hz) for cardiac interval, diastolic and mean pressure could be detected.     

Chondrocyte damage and contact pressures following impact on the rabbit tibiofemoral joint

Epidemiological studies show that tibial plateau fractures comprise about 10% of all below-knee injuries in car crashes. Studies from this laboratory document that impacts to the tibiofemoral (TF) joint at 50% of the energy producing gross fracture can generate cartilage damage and microcracks at the interface between calcified cartilage and underlying subchondral bone in the tibial plateau. These injuries are suggestive of the initiation for a long term chronic disease, such as osteoarthritis. The disease process may be further encouraged by acute damage to chondrocytes in the cartilage overlying areas of occult microcracking. The hypothesis of the current study was that significant damage to chondrocytes in tibial plateau cartilage could be generated in areas of high contact pressure by a single impact delivered to the rabbit TF joint, without a gross fracture of bone. Three rabbits received a single, 13 J of energy blunt insult to the TF joint, while another three animals were used as controls. Cell viability analyses compared chondrocyte damage in impacted versus control cartilage. Two additional rabbits were impacted to document contact pressures generated in the TF joint. The study showed high contact pressures in uncovered areas of the plateau, with a trend for higher pressures in the lateral versus medial facets. A significantly higher percentage of damaged chondrocytes existed in impacted versus the opposite, nonimpacted limbs. Additionally, more chondrocyte damage was documented in the superficial zone (top 20% of cartilage thickness) of the cartilage compared to middle (middle 50% of thickness) and deep (bottom 30% of thickness) zones. This study showed that a single blunt insult to the in situ rabbit TF joint, generating large areas of contact pressure exceeding 20 MPa, produces significant chondrocyte damage in the tibial articular cartilage, especially in the superficial zone, without gross fracture of bone. Future studies will be needed to investigate the long term, chronic outcome of this blunt force joint trauma.     

The development of butterfly settling posture: the role of predators, climate, hostplant-habitat and phylogeny

A model is described that explains the evolution of adult butterfly settling posture. The role of climate and the activity of butterflies is fundamental in determining the effectiveness of primary and secondary visual defence systems based on wing colour and pattern. Both dorsal (open winged) and lateral (closed wing) postures can be regarded as evolutionarily conservative; common postures are found within almost all sub-families. Lateral postures tend to be associated with cool temperate and arctic climates. Conditions that are marginal for activity place an emphasis on the development of underside primary defence, uncompromised by secondary visual defences. In turn, any primary defensive function of the upper surface is reduced but secondary defence may be emphasized. There is interaction between segregation of functions on different wing surfaces and the development of lateral posture. The use of predictable hostplant-habitat structures reduces the role of visual communication in mate-location and facilitates the adoption of a lateral resting posture and a cryptic underside wing pattern. When hostplant-habitat structures are unpredictable but a lateral posture is adopted, primary defence is more important than visual communication for the resting insect. Adjustments of wing morphology facilitate postural conservatism, allowing species to retain particular postures in new hostplant-habitats and climatic zones.