Elastic properties of the forefoot of the Donkey, Equus asinus

The elastic properties of the forefeet of Donkeys, and of tendons removed from the feet, have been investigated in dynamic tests at a frequency chosen to simulate running. The elastic properties of the foot are explained in terms of the properties of individual tendons and check ligaments. The elastic strain energy stored in the foot, during a trotting step, is calculated to be only a little less than the optimum quantity which would minimize the work required of the muscles in this gait. Frictional and viscous energy losses were fairly small in the experiments on feet, and would probably be smaller in the intact animal.     

Elastic properties of the feet of deer (Cervidae)

Dynamic tests have been performed on the feet of deer, and on tendons removed from the feet, to determine their elastic properties. The results have been used to calculate the strain energy stored in each foot while it is on the ground in a fast galloping stride. This is compared with an estimate of the work done by the leg, and the energy-saving rle of tendon elasticity is assessed.     

Elastic Energy Stores in Running Vertebrates

Large mammals save much of the energy they would otherwise needfor running by means of elastic structures in their legs. Kineticand potential energy, lost at one stage of a stride, is storedtemporarily as elastic strain energy and returned later in anelastic recoil. At high speeds, men and kangaroos seem to savein this way more than half the metabolic energy they would otherwiseneed for locomotion. It is shown by means of a generalized model that muscles andtendons could both be important as elastic energy stores. Analysisof films and force records of kangaroos hopping shows that strainenergy stored while the feet are on the ground must be storedmainly distal to the knee. The principal muscles there haveshort fibres, and most of the storage must be in tendons. Investigationof camels shows that tendons in the feet, distal to the ankleand wrist, are especially important. The scope for elastic storagewhile the feet are off the groundis also considered. Though the evidence presented in this paper comes mainly froma few species, the conclusions presumably apply to large mammalsin general.     

Elastic strain energy storage in the feet of running monkeys

Monkeys are 'flat–footed' in comparison to humans, but they are still able to utilize elastic strain energy stores in their feet to reduce the metabolic energy cost of running. During contact with the ground, bending moments act on the foot to produce a 'reversed arch', storing strain energy which is returned in the subsequent elastic recoil. This energy–saving mechanism has been investigated in dynamic bending tests and is discussed in relation to the arched foot of humans.     

Significance of nonsagittal power terms in analysis of a dynamic elastic response prosthetic foot.

Dynamic elastic response prosthetic feet generally utilize a solid ankle, limiting dominant motion to the sagittal plane. However, researchers often use total rotational ankle joint power in the analysis of these feet. This investigation measured joint power terms in each plane for the Carbon Copy High Performance prosthetic foot. The significance of the frontal and transverse plane terms was assessed. Addition of these terms to the dominant sagittal power term revealed only slight differences, indicating that the sagittal power term is likely sufficient.     

Comparison of methods for the calculation of energy storage and return in a dynamic elastic response prosthesis

The standard method used to calculate the ankle joint power contains deficiencies when applied to dynamic elastic response prosthetic feet. The standard model, using rotational power and inverse dynamics, assumes a fixed joint center and cannot account for energy storage, dissipation, and return. This study compared the standard method with new analysis models. First, assumptions of inverse dynamics were avoided by directly measuring ankle forces and moments. Second, the ankle center of rotation was corrected by including translational power terms. Analysis with below-knee amputees revealed that the conventional method overestimates ankle forces and moments as well as prosthesis energy storage and return. Results for efficiency of energy return were varied. Large differences between models indicate the standard method may have serious inadequacies in the analysis of certain prosthetic feet. This research is the first application of the new models to prosthetic feet, and suggests the need for additional research in gait analysis with energy-storing prostheses.     

The extensor assembly in two species of opossum,Philander opossum and Didelphis marsupialis

In considering primate and hominoid phylogeny, the fundamental position assigned to opossums is explained partially by the characteristic morphology of their hands and feet. One of the main functional features of the human hand is the ability to make a stabilized arch of the finger. Because the extensor assembly plays a key role in establishing an arched finger, the extensor systems of the digits of both the hands and feet were studied in two species of opossum, Philander opossum and Didelphis marsupialis. In the foot, two extensor tendons join in each toe to form one tendinous plate, which inserts onto the base of the second phalanx. Lumbricals join this plate along the tibial side, and interosseus insertions are found, although a true interosseus wing is lacking. At the proximal interphalangeal level, a terminal tendon takes its origin from this tendinous plate. This terminal tendon is oval in cross-section and contains elastic structures. Oblique bands arise from this terminal tendon and run proximally along the proximal interphalangeal joint inserting onto the base of the first phalanx. There are elastic structures in the flexor tendon on the dorsal side near its site of insertion. In the hand, the main extensor tendons are arranged differently and the interossei contribute substantially to the extensor assembly. Otherwise, the extensor assembly of the hands and feet are quite similar. The function of the so-called paratendinous intravaginal flexors is discussed as are evolutionary aspects of the extensor assembly.     

The role of tendon elasticity in hopping in a wallaby (Macropus rufogriseus)

The elastic properties of the major tendons of wallaby feet have been investigated in dynamic tensile tests at a frequency close to normal hopping frequencies. In addition, bending tests have been performed on the intertarsal and tarso-metatarsal joints. The data are used to calculate the strain energy stored temporarily in the tendons and ligaments of the legs during a typical hopping stride. The contribution made by stored strain energy to the work required for hopping is assessed.     

A quasi-linear, viscoelastic, structural model of the plantar soft tissue with frequency-sensitive damping properties

Little is known about the structural properties of plantar soft-tissue areas other than the heel; nor is it known whether the structural properties vary depending on location. Furthermore, although the quasi-linear viscoelastic (QLV) theory has been used to model many soft-tissue types, it has not been employed to model the plantar soft tissue. The structural properties of the plantar soft tissue were quantified via stress relaxation experiments at seven regions (subcalcaneal, five submetatarsal, and subhallucal) across eight cadaveric feet. The cadaveric feet were 36.9 +/- 17.4 (mean +/- S.D.) years of age, all free from vascular diseases and orthopedics disorders. All tests were performed at a constant environmental temperature of 35 degrees C. Stress relaxation experiments were performed; different loads were employed for different areas based on normative gait data. A modification of the relaxation spectrum employed within the QLV theory allowed for the inclusion of frequency-sensitive relaxation properties in addition to nonlinear elastic behavior. The tissue demonstrated frequency-dependent damping properties that made the QLV theory ill suited to model the relaxation. There was a significant difference between the elastic structural properties (A) of the subcalcaneal tissue and all other areas (p = 0.004), and a trend (p = 0.067) for the fifth submetatarsal to have less viscous damping (c1) than the subhallucal, or first, second, or third submetatarsal areas. Thus, the data demonstrate that the structural properties of the foot can vary across regions, but careful consideration must be given to the applied loads and the manner in which the loads were applied.     

Tube foot preservation in the Devonian crinoid Codiacrinus from the Lower Devonian Hunsrück Slate,Germany

Fossilized tube feet are described on Codiacrinus schultzei Follmann from the Lower Devonian Hunsrück Slate of Germany. This is the first definitive proof of tube feet on any fossil crinoid. Three lightly pyritized, flattened tube feet are preserved in a single interray of this cladid crinoid. The tube feet were at least 7 mm long. Their preservation is very similar to the tube feet reported previously from a Hunsrück ophiuroid, except that the Codiacrinus tube feet have small papillae, similar to living crinoids.     

The shear mechanical properties of diabetic and non-diabetic plantar soft tissue

Changes in the plantar soft tissue shear properties may contribute to ulceration in diabetic patients, however, little is known about these shear parameters. This study examines the elastic and viscoelastic shear behavior of both diabetic and non-diabetic plantar tissue. Previously compression tested plantar tissue specimens (n=54) at six relevant plantar locations (hallux, first, third, and fifth metatarsal heads, lateral midfoot, and calcaneus) from four cadaveric diabetic feet and five non-diabetic feet were utilized. Per in vivo data (i.e., combined deformation patterns of compression followed by shear), an initial static compressive strain (36-38%) was applied to the tissue followed by target shear strains of 50% and 85% of initial thickness. Triangle waves were used to quantify elastic parameters at both strain levels and a stress relaxation test (0.25 s ramp and 300 s hold) was used to quantify the viscoelastic parameters at the upper strain level. Several differences were found between test groups including a 52-62% increase in peak shear stress, a 63% increase in toe shear modulus, a 47% increase in final shear modulus, and a 67% increase in middle slope magnitude (sharper drop in relaxation) in the diabetic tissue. Beyond a 54% greater peak compressive stress in the third metatarsal compared to the lateral midfoot, there were no differences in shear properties between plantar locations. Notably, this study demonstrates that plantar soft tissue with diabetes is stiffer than healthy tissue, thereby compromising its ability to dissipate shear stresses borne by the foot that may increase ulceration risk.     

类风湿关节炎拇长屈肌腱病变的超声特点

目的:总结类风湿关节炎(RA)患者拇长屈肌腱(FHL)病变的超声特点及二者间的相关性。方法:回顾性分析2010年2月至2011年6月因足部疼痛于我院就诊的60例(120足)RA患者资料。应用彩色多普勒超声诊断仪探查拇长屈肌腱,根据超声探查拇长屈肌腱病变情况的结果将患者分为3组:肌腱完整组(A组,45足),肌腱周围炎症组(B组,49足),肌腱断裂组(C组,26足)。对拇长屈肌腱病变的特点及部位进行描述,并将拇长屈肌腱病变严重程度与患者年龄及病程进行相关性分析。结果:45足肌腱完整,49足出现不同部位的肌腱周围炎症(内踝转折处17足,henrry’s结节处11足,第一跖趾关节跖侧21足),26足发生肌腱断裂(9足发生于内踝转折处,17足发生于跖趾关节跖侧)。肌腱病变的发生率71%。A组平均年龄49.9±9.2岁,病程4.7±2.6年;B组平均年龄56.2±9.2岁,病程16.2±7.4年;C组平均年龄54.7±8.0岁,病程20.9±4.4年。三组间上述参数差异具有统计学意义(P0.05)。结论:拇长屈肌腱是类风湿关节炎足部结构的常见受累部位,其病变多发生于内踝转折处,henrry's结节处及第一跖趾关节跖侧,但henrry’s结节处的断裂少见。在对类风湿关节炎平足患者进行肌腱转位手术时,应充分考量拇长屈肌腱的病变。     

The mechanics of hopping by kangaroos (Macropodidae)

Force platform records and films have been made of kangaroos and a wallaby hopping.
The maximum forces exerted on the ground were about six times body weight. The force exerted on the ground changes direction, throughout the period when the feet are on the ground, so that it is always more or less in line with the centre of mass. Consequently the animal decelerates a little and then accelerates again, during the contact phase.
The fluctuations of potential energy which occur in each hop are slightly smaller at high speeds than at low ones. Fluctuations of external kinetic energy increase with speed and account for most of the energy cost of hopping at high speeds. Fluctuations of internal kinetic energy (due to acceleration and deceleration of the limbs) are relatively small. While the feet are on the ground the extensor muscles of the hip do positive work, those of the knee negative work and those of the ankle negative work followed by positive work. The energy cost of hopping is reduced substantially by elastic storage of energy in the Achilles tendon. In the case of a wallaby hopping at moderate speed the calculated saving was 40%. The maximum stresses developed in leg muscles, tendons and the tibia have been calculated and are discussed in relation to the known properties of muscle, tendon and bone. The trunk pitches as the animal hops because the two legs swing forwards and back simultaneously. Appropriate tail movements reduce, but do not eliminate, this effect. A mathematical theory of hopping is presented and used to investigate the merits of different hopping techniques.
Dawson & Taylor's (1973) discovery that the rate of oxygen consumption of kangaroos decreases a little, as hopping speed increases, is probably to be explained by the increased role of elastic storage of energy at high speeds.     

Studies on some biochemical aspects in the toad after 48 hours of exposure to simulated high altitude

Blood glucose, tissue carbohydrate, total plasma and tissue protein and plasma electrolyte concentrations were estimated in male toads, exposed to simulated high altitude of 12,000, 18,000 and 24,000 feet respectively for 48 hours of continuous exposure in a decompression chamber. Blood glucose and muscle carbohydrate were decreased significantly in animals exposed to 18,000 and 24,000 feet altitude, without having any change in the liver carbohydrate. Muscle carbohydrate was also decreased in 12,000 feet altitude exposed animals. Plasma protein content was increased significantly in 18,000 and 24,000 feet altitude exposed animals, whereas no such change was noted in tissue protein content. A slight increase of plasma sodium concentration was found in animals exposed to 24,000 feet, and a decrease of potassium concentration was also noted in 18,000 and 24,000 feet exposed animals. Magnesium concentration of the plasma was increased in 18,000 and 24,000 feet exposed animals. This animal had also shown an eosinopenia, lymphopenia and neutrophilia when exposed at 24,000 feet high altitude.     

Foot structure and phylogeny in the Viverridae (Carnivora)

The structure of feet is widely used as a diagnostic feature in mammalian taxonomy. The relationship between the lengths of the metacarpals and foot pads are described with regard to plantigrade and digitigrade feet in the Viverridae. Although species in the Herpestinae, Paradoxurinae and Galidiinae vary considerably in size (from 450 g to 10 kg), the increase in length of the metapodial is isometric. Feet in which the metacarpals are less than 15 % of total limb length are plantigrade (Paradoxurinae and Cryptoproctinae) while those larger than 15% are digitigrade (Herpestinae and Galidiinae). The Viverrinae are composed of two natural groups, one in which the species have plantigrade forefeet and digitigrade hind feet and one in which both fore- and hind feet are digitigrade. The Hemigalinae does not appear to be a natural grouping, because the banded palm civet has plantigrade fore- and hind feet while other members of the subfamily have digitigrade feet; it may be better to reclassify the subfamily into three (Hemigalinae, Fossinae and Euplerinae).     

Arteriographic study of the arterial supply of the foot in one hundred cadaver feet

The arterial supply of 100 human cadaver feet (87 cadavers) was investigated by stereoscopic arteriography and was compared phylogenetically to that of the macaque foot. The deep plantar arch was always well developed and complete, whereas the superficial plantar arch was usually slender and incomplete. The first proximal perforating artery arising from the dorsalis pedis artery formed the main component of the deep plantar arch in 82% of the feet. The second proximal perforating artery arising from the dorsal rete contributed to the deep plantar arch in 43% of the feet, and formed most of the arch in one foot. The dorsal rete was classified into four groups of variants based on the arterial source of the second dorsal metatarsal artery. These were the arcuate artery (25%), distal lateral tarsal artery (12%), proximal lateral tarsal artery (6%), and nondorsal rete (57%) variants. In the first intermetatarsal space, the dorsal and plantar metatarsal arteries shared a common trunk in 54% of the feet, but this did not occur in the other intermetatarsal spaces. The second dorsal metatarsal artery arose from the dorsal rete in 43% of the feet, and this artery was quite large, sometimes being the largest of all the dorsal and plantar metatarsal arteries. Variations of the arterial supply found in humans sometimes resembled the typical pattern found in the macaque.     

Coordination of movements of the tube feet and arms of ophiurans during locomotion

The role of the tube feet in locomotion of the ophiuranAmphipholis kochii Lütken is examined. During stepping movements the anterior tube feet attach themselves to the supporting surface and at the end of the step they detach themselves from it. The signal for detachment is deviation of the foot into the posterior (relative to the direction of motion) position. Because of this arrangement of the "stepping" mechanism of the tube feet the task of coordinating their activity with arm movements is greatly simplified. The feet "automatically" attach themselves to the support when the arm which carries them plays the role of motor; conversely, they detach themselves from the support when this arm moves forward. The CNS thus evidently does not participate in foot and arm movement coordination. It simply assigns the general direction of motion to all the feet and coordination takes place "automatically" as a result of the special properties of the "stepping" mechanism of individual feet.Institute of Oceanology, Academy of Sciences of the USSR, Moscow. Institute of Problems of Information Transmission, Academy of Sciences of the USSR, Moscow. Moscow State University. Translated from Neirofiziologiya, Vol. 8, No. 6, pp. 633–639, November–December, 1976.     

Foot Loading Characteristics of Chinese Bound Feet Women: A Comparative Analysis

The custom of bound feet among Chinese women has existed for almost a century. This practice has influenced the daily life of Chinese women, especially during everyday locomotion. The primary aim of this study is to analyze the loading patterns of bound feet. Specifically, the plantar pressure and center of pressure were analyzed for peak pressure, contact area, force time integral, center of pressure displacement velocity and trajectory in the anterior-posterior direction via a comparison with normal feet. The key outcomes from this work were that the forefoot and rearfoot of bound feet bear the whole loading during stance phase. The center of pressure displacement velocity of bound feet was also greatly reduced with the shortening of trajectories. This suggests that the proprioceptive system adjusts motor function to adapt to new loading patterns while maintaining locomotive stability. A biomechanical understanding of bound feet may assist with prevention, treatment and rehabilitation of bound feet disorders.     

A methodology for studying the effects of various types of prosthetic feet on the biomechanics of trans-femoral amputee gait.

This paper reports on a methodology developed for studying the effects of various types of prosthetic feet on the gait of trans-femoral amputees. It is shown that an analysis in three planes of motion of not only the prosthetic, but also the sound limb provides important information on the performance of prosthetic feet. Two male trans-femoral amputees were tested with four different prosthetic feet; the Springlite II, Carbon Copy III, Seattle LightFoot and the Multiflex foot. A detailed analysis of the results of one amputee and a summary of the most important results of a second subject is presented. The tests were carried out at normal (1.16 m s(-1)) and fast (1.56 m s(-1)) walking speeds. Three dimensional gait analysis was carried out to derive the time curves of the joint angles, intersegmental moments and power at the ankle, knee and hip joints at both the prosthetic and sound sides. A higher first peak of the ground reaction force at the sound side with the Seattle LightFoot compared to that with the Springlite II, may be the result of the lower late stance dorsiflexion angle with the former. Compared to the other two feet, the Carbon Copy III and the Springlite II showed higher prosthetic dorsiflexing moments and positive power at late stance, which could assist in the push-off. The 3D intersegmental loads at the ankle and knee can be used as a guide for design and for compilation of standards for testing of lower limb prostheses incorporating flexible feet.