Influence of foot, leg and shoe characteristics on subjective comfort

The purpose of this study was to determine the relationships between foot and leg characteristics, shoe characteristics, and the short-term subjective comfort of three different pairs of athletic shoes. Static measurements of foot dimension and leg angles were taken from eighteen subjects. Subjects rated the comfort of three different athletic shoes for standing, walking and running. The shoes were quantified by internal dimensions, hardness, flexibility and torsional stiffness. Average comfort ratings decreased from standing to walking to running. One shoe seemed suited for only a small group of subjects. In contrast, another shoe was generally comfortable for a large group. Skeletal alignment, specifically eversion angle, was related to comfort for one shoe. Therefore, fit of the shoe is not sufficient for comfort. Skeletal alignment, shoe torsional stiffness and cushioning seem to be mechanical variables which may be important for comfort.

Acute traumatic compartment syndrome of the foot in children

Acute traumatic compartment syndrome of the foot is a sequelae of serious injury to the foot, which, if unrecognized, may result in significant motor and sensory deficits, pain, stiffness, and deformity. It is nearly always associated with fractures, dislocations, and crush injuries to the foot. Vascular injuries and coagulopathic states are also risk factors for the development of an acute foot compartment syndrome. In children, the presentation of an acute foot compartment syndrome may be masked by the pain and edema caused by associated fractures and dislocations. A high index of suspicion is warranted in children presenting with foot injuries that are associated with foot compartment syndrome. Recognition of the signs and symptoms of compartment syndrome in the emergency room are paramount; the diagnosis is best confirmed by multiple compartment pressure readings. The urgency of diagnosis of a compartment syndrome must be underscored, as the complications of a missed foot compartment syndrome includes contractures, claw toe deformity, sensory loss, stiffness, and chronic pain. Prompt orthopaedic consultation is mandatory; urgent compartment fasciotomies are associated with a good clinical outcome.

Developments in orthotic deweighting technology

The ability to unload various aspects of the lower extremity has proven a useful orthotic treatment for a variety of pathologies. This article discusses and categorizes various orthotic techniques.

New concepts in lower limb orthotics

Lower limb orthotics is in the process of a default transformation because of its association with lower limb prosthetics, a mechanical discipline that has translated component and material innovations into balance and velocity function gains to achieve a level of ambulation not possible a generation ago. This article discusses the fundamental mechanical similarities and differences of lower limb orthotics to prosthetics and their application to orthoses designed to improve the gait outcome of patients requiring orthotic intervention.

Bohler incision: an extensile anterolateral approach to the foot and ankle

Incisions in the foot and ankle should allow efficient surgical approaches to the anatomic structures being addressed while preventing chronic neuritic symptoms, extensive scar contractures, soft tissue ischemia or necrosis, and chronic edema. The purpose of this report is to describe the Böhler incision, an extensile approach that provides the surgeon with easy access to the anterior surface of the distal tibia, the anterior talar dome, talar neck, talonavicular, subtalar, and calcaneocuboid joints by allowing direct visualization of these areas. The incision can be extended in both directions, if needed, or it can be used at either end, produces few complications, and closes with a cosmetically acceptable scar that does not produce pressure with shoe wear.

Shape, orientation and spacing of the primary epidermal laminae in the hooves of neonatal and adult horses (Equus caballus)

Circumferential and proximodistal variations in the morphology of the primary epidermal laminae of six neonatal and five adult equine feet were documented. Three parameters were quantified: interlaminar spacing, the orientation of the laminae with respect to the overlying wall, and any angulation within the laminae themselves ('internal angle'). In adult feet, the laminae were most closely spaced at the dorsum, the spacing increasing gradually towards the heels. In foals there was a non-significant trend for the dorsal laminae to be more widely spaced than those in more caudal parts of the foot. In both age groups, the dorsal laminae were almost straight (mean divergence from linearity at all sites 2 degrees ), and were oriented at approximately 90 degrees to the tangent to the overlying wall (mean orientation for all sites 91 degrees ). At the quarters, the laminae were in general oriented caudally relative to the tangential position from their epidermal to their dermal ends (mean orientation of >90 degrees at 12 of 16 sampling sites, where an orientation of >90 degrees defines a 'caudally directed' orientation) and, in general, had a bend within their length (mean absolute value of internal angle for all sites 9 degrees ). At the heels there was greater variability in the data for both laminar orientation and internal angle. Overall, the foal feet showed greater mediolateral symmetry and less proximodistal variation than did the adult feet. In both age groups, rapid spatial changes in laminar morphology were closely associated with the position of the margins of the third phalanx.

The normal foot

The term "normal foot" has many different interpretations. This article reviews some of the ways in which the word "normal" has been used historically to describe the foot. Also discussed are the problems of attempting to determine what should constitute a normal foot and proposed criteria for distinguishing between the normal and the pathological.

Performance of plantar flexor muscles with eccentric and isometric contractions in intact rats

PURPOSE

To examine the changes in performance of active plantar flexor muscles of rats by controlled dorsiflexion (i.e., stretching of muscles) at two angular velocities.

METHODS

Repeated stretches (30) at two velocities of ankle rotation [slow stretch (0.87 rads x s(-1) (i.e., 50 degrees x (s-1))), fast stretch (10.47 rad x s(-1) (i.e., 600 degrees x s-1))] were superimposed on maximally active muscles from an ankle position of 1.57 rad to 0.70 rad (i.e., from 90 degrees to 40 degrees). Repeated isometric contractions (30) of the same duration (1,900 ms) and rest interval (3 min) were performed at 1.13 rad (i.e., 65 degrees). Performance was assessed by measuring the isometric torque at ankle positions of 1.57 and 0.70 rad, work during concentric contractions [range of motion 1.22 rad (i.e., 70 degrees)], and the time to produce 50% of the maximal isometric torque.

RESULTS

Thirty isometric contractions resulted in a linear reduction in torque (total deficit of 13.8% at 1.57 rad), whereas for slow and fast stretches, half of the total, nonlinear deficit at 1.57 rad (about 30%) was completed after six stretches. Increases in half contraction times were larger for stretches than for isometric contractions. Reductions in isometric torque were greater at an ankle position of 1.57 rad than at 0.70 rad. One hour of rest after the repeated stretches and isometric contractions did not restore muscle performance.

CONCLUSIONS

Isometric contractions of skeletal muscle can create a torque deficit which is much less than that after stretches. Repeated fast and slow stretches resulted in similar torque deficits which did not recover after a rest period of 1 h.

Effects of selection for increased body weight, egg production, and shank width on developmental stability in turkeys

Bilateral asymmetry was measured at 20 wk of age for shank length, shank width (width laterally at the dew claw), shank depth (width perpendicular to the dew claw), and face length (between auditory canal opening and the posterior junction of the upper and lower mandible) in three randombred control lines and three selected lines of turkeys. The data were based on 50 or 51 individuals per line and sex subgroup from a single hatch. The lines were grown intermingled with the sexes being grown in different houses. The selected lines had been selected for increased egg production (38 generations), increased 16-wk BW (32 generations), or increased shank width (19 generations) and had a higher level of inbreeding (average = 36.9%) than the randombred controls (RBC; average = 11.6%). The bilateral differences (right minus left) were analyzed for the presence of fluctuating asymmetry (FA; zero signed mean with normal variation), directional asymmetry (DA; signed mean not zero with normal variation), and antisymmetry (AS; zero mean with non-normal distribution). In order to adjust for possible scaling effects, relative asymmetry (RA), in which the mean of the absolute differences between sides was divided by the mean of the two sides and the resulting value was multiplied by 100, was used as a measure of bilateral asymmetry. The randombred control and selected lines were contrasted to study the effect of homozygosity on RA. Likewise, the large-bodied lines (F, FL, and RBC3) were contrasted to the small-bodied lines (RBC1, E, and RBC2) to study the effect of BW on RA. Only two types (FA and DA) of asymmetry were observed in the present study. The level of asymmetry for the traits was ranked as follows: face length > shank width = shank depth > shank length. The individual lines differed in RA for shank length and shank width for both sexes and for shank depth and face length in females. In general, the influence of BW, as measured in the contrast of large-bodied and small-bodied lines, on RA was larger than that of homozygosity, as measured by the contrast of the selected and randombred control lines.

Harmonic analysis of footprint symmetry in healthy adolescents

In the present study, the within-subject normal symmetry of footprint shape and size was analyzed from a mathematical standpoint. On the standardized left and right footprints of 83 adolescents (46 boys, 37 girls) aged 12-15 years (mean 13 years), the outline of each foot excluding the toes was identified and automatically digitized by a computerized video analyzer. Only those subjects with both left and right continuous footprints were further analyzed (36 boys, 26 girls). The footprint area was computed. The footprint shape, independent of its size, was quantified using the elliptic Fourier analysis with a 20-harmonic truncation. The symmetry in shape was quantified on an intra-subject basis by calculating a morphological distance D between the mathematical reconstructions of the left and right footprints of each subject. Symmetry in size was assessed by right-to-left area ratio. Subjects were grouped for sex, and the mean values computed. Mean footprint area was significantly larger in boys than in girls (p < 0.05). Asymmetry in size (area ratio) was 1.01 in girls, 1 in boys. Within-subject symmetry in footprint shape appeared high, with mean morphological distances of 5.95 in girls, and 6.06 in boys. No consistent associations between footprint symmetry and age, height and body weight, or shoe size were found. The mean size-independent shapes of the male and female left and right footprints were also calculated. Together with the analysis of individual asymmetry, they could be used as quantitative parameter in clinical diagnosis.

Age-related reference ranges for fetal foot length

AIM

The aim of this study was to establish age-dependent reference ranges for fetal foot length with gestation as well as for the femur/foot length ratio, based on a mathematical growth model.

METHOD

In a prospective cross-sectional study of 610 pregnancies with sonographically confirmed gestational age (< 12 weeks' gestation), fetal biometry was performed in addition to measurements of fetal foot length between 12 and 42 completed weeks of gestation. Reference ranges for the fetal foot and for the femur/foot length ratio were constructed with an overall coverage of 90% of the measured data, using a previously established method of determining reference bands for growth parameters.

RESULTS

Foot length was noted to level off slightly up to 24 weeks of gestation and it continued in a nearly linear fashion thereafter. The femur/foot length ratio was associated with a mean value of approximately 1 up to 24 weeks of gestation, falling to below 1 after this time point to a value of 0.85 at 41 weeks' gestation. The comparison of the reference ranges established in this study with anatomic and sonographic reference ranges for the fetal foot demonstrates good conformity with the anatomic reference range published by Streeter as early as 1920, and a large degree of conformity with the sonographic reference range developed by Mercer and co-workers.

CONCLUSION

The proposed statistical approach offers reliable reference ranges for the fetal foot and for the femur/foot-ratio as well.

Foot health and shoewear for women

Females are different from males in structure and biomechanics. The foot in the female tends to have a narrower heel in relationship to the forefoot and overall is narrower than a man's foot relative to length. Females tend to pronate their feet more and have smaller Achilles tendons than males, both factors having implications for shoe fit. Although shoes have been worn for thousands of years for the main purpose of protecting feet from the environment, recent studies have implicated shoes as the principal cause of forefoot disorders seen in females. Several authors have reported the harmful effects of shoewear and the greatest factor is a shoe that is improperly fit. With respect to foot disorders in the female, the current study will explore anatomy, biomechanics, common forefoot disorders, and shoewear through the ages, athletic shoewear, and a toe strengthening program.

Evaluation of direct and axon reflex sweating in the mouse

The nicotinic axon reflex-mediated sudomotor response was studied in mice and rats by recording the impressions of sweat droplets made in silicone molds after local injection of nicotine, and compared with sweating induced by acetylcholine and pilocarpine. Nicotine failed to activate mouse plantar sweat glands at any of the concentrations used (from 3 x 10(-6) to 3 x 10(-1) M). On the contrary, both acetylcholine and pilocarpine produced a dose-dependent increase in the number of secreting sweat glands. The location of sweat glands reactive to pilocarpine and acetylcholine was similar and restricted to the pads near the site of injection. We conclude that the sudomotor axon reflex response mediated by nicotinic receptors is not present in the mouse and the rat.

Measures of postural stability are not predictors of recovery from large postural disturbances in healthy older adults

OBJECTIVES

To determine, in healthy older adults, the relationship between postural steadiness, stability limits, and the ability to recover balance from three postural disturbances requiring anteriorly directed stepping responses.

DESIGN

Analysis of multiple motor tasks in a cross-sectional sample of healthy older adults.

SETTING

A biomechanics research laboratory.

PARTICIPANTS

Fifty women and 29 men aged 65 or older, all healthy, living in the community, participated in this study. Subjects were examined by a geriatrician to identify the presence of exclusionary factors.

MEASUREMENTS

Anterior-posterior and medial-lateral excursion distances of the center of pressure during quiet standing (postural steadiness), static leaning (static stability limits), and dynamic swaying (dynamic stability limits) were determined from ground reaction forces measured by a strain gauge forceplate. Within the same group of subjects, the maximum angle of forward lean from which a subject could recover with a single step, the ability to recover balance in response to an accelerated support surface, and the ability to recover balance after being tripped were determined.

RESULTS

Recovery from the three types of postural disturbances were found to be statistically independent. The postural steadiness and the stability limit variables were only weakly correlated. Postural steadiness and stability limits were not related to the maximum recoverable angle of lean. The average medial-lateral center of pressure speed during the postural steadiness test was significantly slower for those who failed to recover after tripping than for the subjects who recovered successfully. However, a logistic regression model failed to achieve statistical significance, suggesting that the difference may not be functionally important. The anterior-posterior static stability limits were significantly larger for subjects who recovered successfully than for those who failed to recover during the accelerated support surface test. Although logistic regression suggested that a reduced anterior-posterior stability limit represents a risk factor for failure to recover during this task, only nine of 28 failures could be properly classified, thus diminishing the functional importance of this finding.

CONCLUSIONS

Because recovery following postural disturbances could not generally be predicted from measures of postural stability, these findings suggest that these measures of postural stability are of limited utility in identifying potential anteriorly directed fallers in healthy older adults.

Reconstruction of the burned foot

Burns of the feet pose unique and difficult problems in initial management, reconstruction, and the attainment of long-term functional results. The primary reconstructive goals for this region are unimpeded ambulation and weightbearing on a pain-free limb. These objectives can be achieved by adherence to established principles of wound management, a clear delineation of the reconstructive requirements of the foot, and a team approach toward attaining these goals. The goal of any method of reconstruction should be the restoration of function within a reasonable aesthetic appearance. With the foot, in addition to adequate healing, the goal should be the ability to walk again, wear normal footwear, and, if possible, return to work.

Mechanics of tarsal disintegration and plantar ulcers in leprosy by stress analysis in three dimensional foot models

This paper describes three dimensional two arch models of feet of a normal subject and two leprosy subjects, one in the early stage and the other in the advanced stage of tarsal disintegration, used for analysis of skeletal and plantar soft tissue stresses by finite element technique using NISA software package. The model considered the foot geometry (obtained from X-rays), foot bone, cartilages, ligaments, important muscle forces and sole soft tissue. The stress analysis is carried out for the foot models simulating quasi-static walking phases of heel-strike, mid-stance and push-off. The analysis of the normal foot model shows that highest stresses occur at push-off over the dorsal central part of lateral and medial metatarsals and dorsal junction of calcaneus and cuboid and neck of talus. The skeletal stresses, in early state leprosy with muscle paralysis and in the advanced stage of tarsal distintegration (TD), are higher than those for the normal foot model, by 24% to 65% and 30% to 400%, respectively. The vertical stresses in the soft tissue at the foot-ground interface match well with experimentally measured foot pressures and for the normal and leprosy subjects they are the highest in the push-off phase. In the leprosy subject with advanced TD, the highest soft tissue stresses and shear stresses (about three times the normal value) occur in push-off phase in the scar tissue region. The difference in shear stresses between the sole and the adjacent soft tissue layer in the scar tissue for the same subject is about three times the normal value. It is concluded that the high bone stresses in leprosy may be responsible for tarsal distintegration when the bone mechanical strength decreases due to osteoporosis and the combined effect of high value of footsole vertical stresses, shear stresses and the relative shear stresses between two adjacent soft tissue layers may be responsible for plantar ulcers in the neuropathic leprosy feet.

Plantar dermatoglyphic features of the Urhobos of southern Nigeria

OBJECTIVE

To establish the dermatoglyphic features of the Urhobos of southern Nigeria.

DESIGN

Cross sectional study of randomly selected Urhobo subjects.

SETTING

Department of Anatomy, College of Health Sciences, University of Port Harcourt, Port Harcourt, southern Nigeria.

MAIN OUTCOME

Plantar and digital pattern types were determined and Dankmeijer's (DI) and pattern intensity (PII) indices were calculated.

RESULTS

Males showed greater pattern types than females except in loops and whorls of the digits, where females showed greater numbers than males. The pattern intensity index was higher in females than in males. What appears characteristic to this group however, was the presence of few whorl distribution in the small toe in female subjects which was absent in male subjects.

CONCLUSION

This study thus provide normal dermatoglyphic features for the Urhobos of Southern Nigeria and also highlighted possible distinguishing dermtoglyphic difference between the Ibos and Urhobos of Southern Nigeria.

Foot flare and foot axis

Most commercial footwear is designed and manufactured on a curved last, although the amount of curvature of the last and the turning point of the last centerline have not been formally determined. In this study, we used principal component analysis to determine the foot axis so that lasts that match feet can be produced, resulting in a good fit. In evaluating 50 Hong Kong Chinese participants, we found that the center of the foot is located at approximately 52% of the foot length measuring from the back of the foot (SD = 0.65%) and that Hong Kong participants have a mean inflare (inward curvature) of 3.2 degrees. The foot center and inflare measures will help determine the fit between footwear and feet. Applications of this research include the ability to incorporate foot flare into the design and manufacture of footwear.

On standardizing the MR image intensity scale

The lack of a standard image intensity scale in MRI causes many difficulties in image display and analysis. A two-step postprocessing method is proposed for standardizing the intensity scale in such a way that for the same MR protocol and body region, similar intensities will have similar tissue meaning. In the first step, the parameters of the standardizing transformation are "learned" from a set of images. In the second step, for each MR study these parameters are used to map their histogram into the standardized histogram. The method was tested quantitatively on 90 whole-brain studies of multiple sclerosis patients for several protocols and qualitatively for several other protocols and body regions. Measurements using mean squared difference showed that the standardized image intensities have statistically significantly (P < 0.01) more consistent range and meaning than the originals. Fixed gray level windows can be established for the standardized images and used for display without the need of per case adjustment. Preliminary results also indicate that the method facilitates improving the degree of automation of image segmentation. Magn Reson Med 42:1072-1081, 1999.

On standardizing the MR image intensity scale

The lack of a standard image intensity scale in MRI causes many difficulties in image display and analysis. A two-step postprocessing method is proposed for standardizing the intensity scale in such a way that for the same MR protocol and body region, similar intensities will have similar tissue meaning. In the first step, the parameters of the standardizing transformation are "learned" from a set of images. In the second step, for each MR study these parameters are used to map their histogram into the standardized histogram. The method was tested quantitatively on 90 whole-brain studies of multiple sclerosis patients for several protocols and qualitatively for several other protocols and body regions. Measurements using mean squared difference showed that the standardized image intensities have statistically significantly (P < 0.01) more consistent range and meaning than the originals. Fixed gray level windows can be established for the standardized images and used for display without the need of per case adjustment. Preliminary results also indicate that the method facilitates improving the degree of automation of image segmentation. Magn Reson Med 42:1072-1081, 1999.

Body proportions during long-term growth hormone treatment in girls with Turner syndrome participating in a randomized dose-response trial

To assess body proportions in girls with Turner syndrome (TS) during long term GH treatment, height, sitting height (SH), hand (Hand) and foot (Foot) lengths, and biacromial (Biac) and biiliacal (Biil) diameters were measured in 68 girls with TS participating in a GH dose-response trial. These previously untreated girls with TS, aged 2-11 yr, were randomly assigned to 1 of 3 GH dosage groups: group A, 4 IU/m2 x day; group B, first year 4 and thereafter 6 IU/m2 x day; group C, first year 4, second year 6, and thereafter 8 IU/m2 x day. Seven-year data were evaluated to assess the effect of GH treatment on body proportions during childhood. In addition, data from all girls who had reached adult height were evaluated to determine the effect on the adult body proportions. All results were adjusted for age and sex and expressed as SD scores using reference values of healthy Dutch girls. To describe the proportions of SH, Hand, Foot, Biac, and Biil to height, these values were adjusted for the SD score of height and were expressed as shape values, using the formula, e.g. for SH: shape SH = (SH SD score - height SD score)/square root(2 - 2 x correlation coefficient between SH and height in the reference population). Furthermore, SD scores using references of untreated girls with TS were calculated for height and SH. Values less than -2 or more than +2 were considered outside the normal range. At baseline, the shape values of all measurements were significantly higher than zero, but most mean shape values were still within the normal range. Seven-year data of 64 girls and adult height data of 32 girls showed that an increase in height was accompanied by an even higher increase in Foot, resulting in mean SD scores above zero and shape values of +2 and higher. The increase in the shape value of Foot was significantly higher in groups B and C compared to that in group A after 7 yr of GH treatment, but there were no significant differences between the GH dosage groups in the girls who had reached adult height. The shape values of SH had decreased to values closer to zero after reaching adult height, especially in group A. A similar pattern in the relationship of SH to height was seen using references of girls with TS. No significant changes in the other proportions were found after reaching adult height. In conclusion, on the average, untreated girls with TS have relatively large trunk, hands, and feet, and broad shoulders and pelvis compared to height. The increase in height after long term GH treatment is accompanied by an even higher increase in Foot and a moderate improvement of the disproportion between height and SH. Recently published reference data from untreated adults with TS and the results of a different patient group receiving a comparable GH dosage suggest that the disproportionate growth of feet has to be considered a part of the natural development in TS, but might be influenced by higher GH dosages. The development of large feet can play a role in the decision of the girl to discontinue GH treatment in the last phase of growth.

Coincident development of sesamoid bones and clues to their evolution

Sesamoid bones form within tendons in regions that wrap around bony prominences. They are common in humans but variable in number. Sesamoid development is mediated epigenetically by local mechanical forces associated with skeletal geometry, posture, and muscular activity. In this article we review the literature on sesamoids and explore the question of genetic control of sesamoid development. Examination of radiographs of 112 people demonstrated that the relatively infrequent appearances of the fabella (in the lateral gastrocnemius tendon of the knee) and os peroneum (in the peroneus longus tendon of the foot) are related within individuals (P < 0.01). This finding suggests that the tendency to form sesamoids may be linked to intrinsic genetic factors. Evolutionary character analyses suggest that the formation of these sesamoids in humans may be a consequence of phylogeny. These observations indicate that variations of intrinsic factors may interact with extrinsic mechanobiological factors to influence sesamoid development and evolution.