Biomechanical effects of foot orthoses during walking

The purpose of this study was to quantify kinetic and kinematic effects during the stance phase of walking using three different foot orthoses. All test subjects were measured under five test conditions with 10 repetitions each. The test conditions included: neutral orthosis (tested twice) and three different orthoses (posting, molding and posting combined, proprioceptive). Whereas most previous studies rely on healthy subjects to describe effects of orthoses during gait, the present study used eight patients (all pes valgus). Standard gait analysis was used with force plates (KISTLER) and an optoelectric measuring system (VICON). The results show that the combined molding and posting foot orthosis significantly reduced eversion and eversion moments during walking compared to a posting type and a proprioceptive orthosis in several test parameters. EMG measurements with fine wire electrodes on three of the test subjects revealed that the activity pattern of the tibialis posterior muscle can considerably change between subjects but may not be used to explain apparent individual effects. The results suggest that for subjects with pes valgus a combined molding and posting orthoses reduces eversion best and that individual variations may be due to subject dependent proprioception, internal foot mechanics and/or a combination of both.     

Spine stabilization by psoas muscle during walking and running

European Spine Journal -     

Gender-specific differences of the foot during the first year of walking

BACKGROUND: It is is well established that gender-specific differences in foot shape exist in adults. However, no information is available whether these differences are present already in children's feet and at what stage in the development these changes become evident. METHODS: Plantar pressure patterns and footprints of 42 healthy infants (20 male, 22 female) were evaluated over the course of one year and compared regarding gender-specific differences. The age at initial evaluation of the children was 16.1 months, and they were evaluated every 3 months. Anthropometric data, foot shape, and foot loading parameters for the whole foot, as well as for selected regions of interest, were evaluated. RESULTS: Significant differences in the foot shape and dynamic foot loading parameters were noted between boys and girls already at this young age. Boys demonstrated a broader midfoot, indicating a lower arch. Girls showed a more pronounced dynamic loading, especially in the heel and forefoot regions. CONCLUSIONS: The differences seen in this study should be taken into account by the shoe industry responsible for the design of children's shoes to support healthy development of the growing foot. Foot disorders are not only caused by hereditary factors but may be due to disturbances during foot growth and development. Since today's society is dependent on wearing shoes for foot protection, shoes should be designed not only according to the fashion demands of the customers but also to the biomechanical needs. Therefore, it is important to ensure that shoes fit the shape of the feet, which is different for boys and girls already when walking begins.     

The effect of terrain on foot pressures during walking

BACKGROUND: High plantar pressures are associated with the development of foot ulcers in people with diabetic neuropathy. The effect of terrain on plantar pressures during walking has not been fully explored. METHODS: Twenty 23- to 40-year-old subjects with no known musculoskeletal pathology walked across three terrains: padded carpet (R), grass (G), and concrete (C) while wearing Novel Pedar (Novel Electronics Inc. GMBH, Munich, Germany) insoles with and without shoes. Pressures were collected at 50 Hz. The sole of the foot was divided into: heel (H), lateral midfoot (LM), medial midfoot (MM), big toe and first metatarsal head (BT), and lateral toes and metatarsal heads (LT). Repeated measures ANOVA identified differences in pressures, forces, and contact areas across terrains. Post hoc Bonferroni adjustments were used to accept an overall alpha level of 0.05. RESULTS: Peak pressure (PP), maximal mean pressure (MMP) and pressure time integral (PTI) were significantly higher (p < 0.01) when walking barefoot on concrete than on grass or carpet for all foot regions except MM and LM. The percent increase in the three pressure variables ranged from 21% to 43%. Grass and carpet PP, MMP, and PTI were similar for the BT and LT. Wearing shoes significantly increased contact area and decreased all pressure variables on all three terrains. CONCLUSION: Walking barefoot, especially on concrete was associated with higher plantar pressure variables. Wearing shoes eliminated terrain differences in pressure except under the lesser toes. Persons with insensate feet should avoid walking barefoot on hard surfaces to avoid excessive plantar pressures. Wearing shoes and covering hard floors with nonslip, padded rugs may decrease plantar pressures and the risk of ulceration.     

Redistribution of foot pressure in healthy adults during sideslope walking

Normal adult plantar pressures were measured during both level and sideslope walking. Sideslope pressures increased, depending on the relative position of the foot on the slope. With upslope placement, pressures increased significantly at the midfoot (approximately 20%) and fifth metatarsal (approximately 16%). With downslope placement, pressure increased predominantly beneath the first metatarsal (approximately 11%). Pressure changes were relatively small at the heel (approximately 3%) and central metatarsals (approximately 4%). Significant increases occurred on sideslopes as small as 2 degrees. Since gradients of this size are likely to be encountered commonly in outdoor daily activities, this finding may have substantial implications for individuals with peripheral neuropathy.     

A study of the distribution of load under the normal foot during walking

Summary A computerised instrumentation system which measures the distribution of vertical load under the foot has been used to measure and record the loading under 148 normal feet during walking. The correlations and variations with load, contact time, sex, age and angle of the toe out are discussed.

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Résumé Un système informatisé, qui mesure la répartition des charges verticales au niveau des pieds, a été utilisé pour mesurer et pour enregistrer 148 pieds normaux pendant la marche. Les auteurs discutent les corrélations et les variations en fonction du poids, du temps de contact avec le sol, du sexe, de l'âge et de la désaxation des orteils.

     

Sex-related differences in coordination and variability among foot joints during running

Background

Women, as compared with men, have a higher proportion of injuries in the ankle/foot region. However, the reason for this sex-related difference in foot injuries remains unclear. Recently, joint coordination and variability of coordination have been suggested to be a critical index for defining both the state of injury and the potential risk of injury. The purpose of this study was to investigate sex-related differences in coordination and variability among the foot joints during running.

Methods

Twelve healthy men and 12 healthy women ran on a treadmill. A modified vector coding technique was used to identify coordination and variability among foot joints involving the shank, rearfoot, midfoot, and forefoot segments, and categorized into the following four coordination patterns: in-phase with proximal dominancy, in-phase with distal dominancy, anti-phase with proximal dominancy, and anti-phase with distal dominancy.

Results

There were no differences in all spatiotemporal parameters and in the foot strike angle between men and women. Coordination of variability of the foot joints during running was similar between men and women, but the anti-phase with proximal dominancy in proportion of frontal rearfoot-shank vs. midfoot-rearfoot couple (men; 7.2%, women; 13.9%) and midfoot-rearfoot vs. forefoot-midfoot couple (men; 18.6%, women; 39.8%) in women was significantly increased compared to that in men. Other all coordination of the foot joints during running differed between men and women, and effect sizes of these parameters were all large.

Conclusion

The results may be useful for understanding the underlying mechanism contributing to differences in injury risk in men and women, and may provide novel data on foot joint coordination and variability that could be used as reference data for both biomechanical and clinical running studies.

     

Relationship between foot pronation and rotation of the tibia and femur during walking.

The purpose of this study was to test the hypothesis that the magnitude and timing of peak foot pronation would be predictive of the magnitude and timing of peak rotation of tibia and femur. Thirty subjects who demonstrated a wide range of pronation participated. Three-dimensional kinematics of the foot, tibia, and femur segments were recorded during self-selected free walking trials using a six-camera VICON motion analysis system. Regression analysis demonstrated that the magnitude and timing of peak pronation was not predictive of the magnitude and timing of tibial and femoral rotation. The lack of a relationship between peak foot pronation and the rotation of the tibia and femur is contrary to the clinical hypothesis that increased pronation results in greater lower extremity rotation. It would seem, therefore, that the relationship between foot pronation and rotation of the lower extremity segments should be assessed on a patient-by-patient basis.     

Dynamic changes in the medial arch of the foot in childhood during walking

The purpose of this study was to estimate the period of gait maturation from the viewpoint of changes of the medial arch of the foot. Gait studies are performed on normal children between the ages of seven and twelve years and compared with those of normal adults. The first peak of lengthening of the medial arch of the foot, caused mainly by the vertical force on the foot, is shortened with age and becomes almost the same as the adult at nine years of age. In the late stage of the stance phase, the pattern of the medial arch becomes almost the same as the adult at twelve years of age. It is suggested that the medial arch of the foot during walking is well established at the age of nine years in foot flexibility, and finally transformed into an adult pattern at the age of twelve years in relation to foot flexibility and muscle force.     

Effect of foot orthoses on rearfoot complex kinematics during walking gait

The aim of this study was to quantify the effect of anti-pronatory and anti-supinatory foot orthoses on the angular displacement, velocity and accelerations of the rearfoot complex during gait. The transverse plane motion of the leg relative to the foot was used to indicate rearfoot complex pronation and supination. Three dimensional gait analysis on 12 subjects was used to derive the changes in the rearfoot kinematics due to the orthoses. The anti-pronatory orthoses decreased the range of pronation during the contact phase (p=0.0002) and the total range of rearfoot complex motion (p=0.000002), whereas anti-supinatory orthoses increased the range of pronation during the contact phase (p=0.00006) and the total range of rearfoot motion (p=0.049). Anti-pronatory orthoses also decreased the initial peak in pronation velocity during the contact phase of gait (p=0.006). Neither orthosis had a statistically significant effect on rearfoot complex acceleration.     

Development of an artificial vessel lined with human vascular cells

OBJECTIVES: Thrombogenity of small-diameter vascular prostheses might be reduced by complete coverage of the luminal surface with vascular cells. We investigated cell seeding on polyurethane vascular prostheses. METHODS: Thirty polyurethane vascular prostheses were divided into 3 groups of 10 each: group A, diameter of 20 mm and gamma-sterilized; group B, diameter of 4 mm and gamma-sterilized; and group C, diameter of 4 mm and ethylene oxide sterilized. Human smooth muscle cells, fibroblasts, and endothelial cells were isolated from saphenous vein segments and expanded in culture. Five polyurethane vascular prostheses of each group were seeded with endothelial cells alone (mean, 4.8 +/- 1.2 x 10(6) cells), and the remaining 5 polyurethane vascular prostheses were preseeded with a mixed culture of fibroblasts and smooth muscle cells (mean, 7.7 +/- 2.3 x 10(6) cells), followed by endothelial cell seeding (mean, 4.4 +/- 0.9 x 10(6) cells). Seven days after cell seeding, the polyurethane vascular prostheses were perfused under a pulsatile flow (80 pulses/min, 140/80 mm Hg, and 120 mL/min) for 2 hours. Specimens were taken after each seeding procedure both before and after perfusion and then examined both with a scanning electron microscope and immunohistochemically. RESULTS: Isolated endothelial cell seeding revealed better initial adhesion in groups A and B than in group C (63% vs 33%). After 7 days, the cells had covered approximately 80% of the luminal surface in groups A and B, whereas group C cells rounded up and lost adhesion. After perfusion testing of group A and B prostheses, only 10% of the surface was still covered with endothelial cells. Preseeding with the mixed culture again revealed a better initial adhesion in groups A and B compared with that in group C (76% vs 41%). In groups A and B endothelial cell seeding (adhesion, 72%) resulted in a confluent endothelial cell layer. The results of immunohistochemical staining were positive for collagen IV, laminin, CD31, and Factor VIII. In group C only isolated cells were found after each seeding procedure, which rounded up and vanished during the next days. Perfusion testing of group A and B prostheses revealed that the confluent cell layer remained stable, with only small defects (<10% of the surface). The cells stained positivively for endothelial nitric oxide synthase. CONCLUSION: Seeding of a mixed culture out of fibroblasts and smooth muscle cells resulted in improved endothelial cell adhesion and resistance to shear stress. This outcome was caused by an increased synthesis of extracellular matrix proteins. Cell attachment was better on gamma-sterilized polyurethane vascular prostheses compared with on those undergoing ethylene oxide sterilization.     

Extrinsic muscle activity, foot motion and ankle joint moments during the stance phase of walking

This study examined stance phase foot kinematics, kinetics and electromyographic (EMG) activity of extrinsic muscles of 18 healthy males. Three-dimensional kinematic and kinetic data were obtained via video analysis of surface markers and a force plate. Ankle joint moments are described about orthogonal axes in a segmental coordinate system. Kinematic data comprise rearfoot and forefoot motion, described about axes of a joint coordinate system, and medial longitudinal arch height. Surface EMG was obtained for tibialis anterior, soleus, gastocnemius medialis and lateralis, peroneus longus and peroneus brevis and extensor digitorum longus. It was concluded that the demands on the controlling muscles are greatest prior to foot flat and after heel rise. Tibialis anterior restrained rearfoot plantarflexion from heel contact to 10% stance, and eversion between 10% stance and footflat. Activity in peroneus longus was consistent with its role in causing eversion after heel contact, then as a stabiliser of the forefoot after heel rise. Activity in peroneus brevis suggested a role in restraining lateral rotation of the leg over the foot, late in stance.     

Transverse patellar fractures“0” fixation system Double-head cannulated compression screw

Purpose: This study evaluated the angular kinematic and moment of the ankle and foot during shod walking and barefoot walking in individuals with unilateral chronic ankle instability (CAI).Methods: Recreational soccer players with unilateral CAI were recruited for this cross sectional study conducted between January and August 2019. A total of 40 participants were screened for eligibility but only 31 met the inclusion criteria based on the methods of Delahunt et al and Gribble et al. Except for 3 participants not attending the evaluation session, 28 participants were finally included. A three dimensional motion analysis system made up of ProReflex motion capture unit and an AMTIb Kistler force plate, embedded in the middle of nine meter walkway, were used to assess the ankle and foot angles and moment during shod walking and barefoot walking conditions. A Statistical Package for Social Sciences (version 20.0) was used to analyze data.Results: During shod walking, the ankle joint plantar-flexion range of motion (ROM) at 10% of the gait cycle (GC) and dorsiflexion ROM at 30% of the GC were significantly higher than those during barefoot walking for both feet (p = 0.001, 0.001, 0.027, and 0.036 respectively). The inversion ROM during shod walking was significantly higher than that during barefoot walking for both feet at 10% and 30% of the GC (p = 0.001. 0.001, 0.001, and 0.042 respectively). At 10% of the GC, the eversion moment was significantly higher between barefoot and shod walking for both feet (both p = 0.001). At 30% of the GC, there was no significant difference between shod and barefoot walking plantar-flexion moment of both feet (p = 0.975and 0.763 respectively), and the eversion moment of both feet (p = 0.116 and 0.101 respectively).Conclusion: At the early stance, shod walking increases the ankle plantar-flexion and foot inversion ROM, and decreases the eversion moment for both feet in subjects with unilateral CAI. Therefore, the foot wearing condition should be considered during evaluation of ankle and foot kinematics and kinetics.