Toe Region Research Articles

Determining the contribution of glycosaminoglycans to tendon mechanical properties with a modified shear-lag model

Tendon has a complex hierarchical structure composed of both a collagenous and a non-collagenous matrix. Despite several studies that have aimed to elucidate the mechanism of load transfer between matrix components, the roles of glycosaminoglycans (GAGs) remain controversial. Thus, this study investigated the elastic properties of tendon using a modified shear-lag model that accounts for the structure and non-linear mechanical response of the GAGs. Unlike prior shear-lag models that are solved either in two dimensions or in axially symmetric geometries, we present a closed-form analytical model for three-dimensional periodic lattices of fibrils linked by GAGs. Using this approach, we show that the non-linear mechanical response of the GAGs leads to a distinct toe region in the stress–strain response of the tendon. The critical strain of the toe region is shown to decrease inversely with fibril length. Furthermore, we identify a characteristic length scale, related to microstructural parameters (e.g. GAG spacing, stiffness, and geometry) over which load is transferred from the GAGs to the fibrils. We show that when the fibril lengths are significantly larger than this length scale, the mechanical properties of the tendon are relatively insensitive to deletion of GAGs. Our results provide a physical explanation for the insensitivity for the mechanical response of tendon to the deletion of GAGs in mature tendons, underscore the importance of fibril length in determining the elastic properties of the tendon, and are in excellent agreement with computationally intensive simulations.

Shear strength of sediments approaching subduction in the Nankai Trough, Japan as constraints on forearc mechanics

The mechanical behavior of the plate boundary fault zone is of paramount importance in subduction zones, because it controls megathrust earthquake nucleation and propagation as well as the structural style of the forearc. In the Nankai area along the NanTroSEIZE (Kumano) drilling transect offshore SW Japan, a heterogeneous sedimentary sequence overlying the oceanic crust enters the subduction zone. In order to predict how variations in lithology, and thus mechanical properties, affect the formation and evolution of the plate boundary fault, we conducted laboratory tests measuring the shear strengths of sediments approaching the trench covering each major lithological sedimentary unit. We observe that shear strength increases nonlinearly with depth, such that the (apparent) coefficient of friction decreases. In combination with a critical taper analysis, the results imply that the plate boundary position is located on the main frontal thrust. Further landward, the plate boundary is expected to step down into progressively lower stratigraphic units, assisted by moderately elevated pore pressures. As seismogenic depths are approached, the décollement may further step down to lower volcaniclastic or pelagic strata but this requires specific overpressure conditions. High‐taper angle and elevated strengths in the toe region may be local features restricted to the Kumano transect.

English

BACKGROUND : Dermatoglyphics is the scientific study of epidermal ridges and their configurations on the palmar region of hand and fingers and plantar region of foot and toes. The myocardial infarction is almost always caused by coronary artery disease. Against the genetic background of dermatoglyphic patterns and coronary artery disease, the study was undertaken to determine the correlation between them. AIMS To do a comparative study of the dermatoglyphics (finger tip pattern) in patients with myocardial infarction and control group and to assess the usefulness of finger tip pattern in serving as a predictor for myocardial infarction. SETTING AND DESIGN: The study was done in 200 persons of age between 40 to 75 years . Out of them,100 were confirmed cases of CAD and 100 were normal healthy controls. METHODS AND MATERIAL: The finger and palmar prints of both hands were taken on white paper by Ink method and kores duplicating ink was used for taking the prints . STATISTICAL ANALYSIS USED: In statistical analysis SPSS software was used and Z test was used. The p value less than .001 and .05 was considered statistically significant. RESULTS AND CONCLUSIONS: It was found that the total number of whorls are significantly higher in patients with myocardial infarction and total number of loops are significantly lower in patients with CAD. Such difference was significant only in right thumb, left thumb, right ring finger and left little finger. Similarly, loops were significantly less in right thumb, right index finger, right and left little finger. With regard to high incidence of MI, it can be concluded that the knowledge of dermatoglyphics in patients with MI can be utilized to find out genetic correlation. The existence of such relation might be important in the screening program for prevention of MI.

Relationship between tendon stiffness and failure: a metaanalysis

Tendon is a highly specialized, hierarchical tissue designed to transfer forces from muscle to bone; complex viscoelastic and anisotropic behaviors have been extensively characterized for specific subsets of tendons. Reported mechanical data consistently show a pseudoelastic, stress-vs.-strain behavior with a linear slope after an initial toe region. Many studies report a linear, elastic modulus, or Young's modulus (hereafter called elastic modulus) and ultimate stress for their tendon specimens. Individually, these studies are unable to provide a broader, interstudy understanding of tendon mechanical behavior. Herein we present a metaanalysis of pooled mechanical data from a representative sample of tendons from different species. These data include healthy tendons and those altered by injury and healing, genetic modification, allograft preparation, mechanical environment, and age. Fifty studies were selected and analyzed. Despite a wide range of mechanical properties between and within species, elastic modulus and ultimate stress are highly correlated (R(2) = 0.785), suggesting that tendon failure is highly strain-dependent. Furthermore, this relationship was observed to be predictable over controlled ranges of elastic moduli, as would be typical of any individual species. With the knowledge gained through this metaanalysis, noninvasive tools could measure elastic modulus in vivo and reasonably predict ultimate stress (or structural compromise) for diseased or injured tendon.

Characterisation of clinical and newly fabricated meshes for pelvic organ prolapse repair

Clinical meshes used in pelvic organ prolapse (POP) repair are predominantly manufactured from monofilament polypropylene (PP). Complications from the use of these meshes in transvaginal kits, including mesh exposure and pain, have prompted two public health notifications by the FDA. The aim of this study was to compare several clinical PP POP meshes to new fabricated POP meshes, knitted from alternative polymers, for their mechanical properties using standard and clinically relevant multi-axial testing methods. Five new meshes were warp knitted to different architectures and weights from polyamide and polyetheretherketone monofilaments. A composite mesh of a polyamide mesh incorporating a gelatin layer was also fabricated to enable the potential delivery of cells on these meshes. Meshes were assessed for their structural characteristics and mechanical properties, using uniaxial stiffness, permanent strain, bending rigidity and multi-axial burst strength methods. Results were compared to three clinical urogynaecological polypropylene meshes: Polyform®, GynemeshTMPS, and IntePro®. New fabricated meshes were uniaxially less stiff (less than 0.24N/mm and 1.20N/mm in toe and linear regions, respectively) than the Gynemesh (0.48N/mm and 2.08N/mm in toe and linear regions, respectively) and IntePro (0.57N/mm in toe region) clinical meshes, with the gelatin coated PA mesh exhibiting lower permanent strain than Polyform clinical mesh (8.1% vs. 23.5%). New meshes had lower burst stiffness than Polyform (less than 16.9N/mm for new meshes and 26.6N/mm for Polyform). Within the new mesh prototypes, the PA meshes, either uncoated (4.7–5.7μNm) or with gelatin coating (16.7μNm) possessed lower bending rigidity than both Polyform and Gynemesh (46.2μNm and 36.4μNm, respectively). The new fabricated mesh designs were of similar architecture, but with some improved mechanical properties, compared to clinical POP meshes. Multi-axial analysis of new and clinical mesh designs provides greater discriminatory power in analysing mesh mechanical properties for clinical applications.

Strain rate dependent properties of human craniovertebral ligaments

Craniovertebral ligaments were tested to failure under tensile loading. Ligaments tested included: transverse ligament, anterior atlanto occipital membrane, posterior atlanto occipital membrane, capsular ligaments between Skull–C1 and C1–C2, anterior atlantoaxial membrane, posterior atlantoaxial membrane and the tectorial membrane/vertical cruciate/apical/alar ligament complex.The objective of this study was to obtain mechanical properties of craniovertebral ligaments of a younger population, at varying strain rates representative of automotive crash scenarios, and investigate rate and gender effects for use in numerical models of the cervical spine.There have been few studies conducted on the mechanical properties of human craniovertebral ligaments. Only one study has tested all of the ligaments, and previous studies use older age specimens (mean age 67, from most complete study). Further, tests were often not performed at elongation rates representative of car crash scenarios. Previous studies did not perform tests in an environment resembling in vivo conditions, which has been shown to have a significant effect on ligament tensile behaviour.Fifty-four craniovertebral ligaments were isolated from twenty-one spines, and tested to failure in tension under simulated in vivo temperature and hydration levels, at quasi-static (0.5s−1) and high strain rates (150s−1). Values for failure force, failure elongation, stiffness, and toe region elongation were obtained from force–displacement curves. Values were analyzed for strain rate and gender effects.Increased strain rate produced several significant effects including: higher failure forces for the transverse ligament and capsular ligament (Skull–C1), lower failure elongation for the tectorial membrane complex, higher stiffness for the tectorial membrane complex and capsular ligament (Skull–C1), and lower toe region elongation for capsular ligament (Skull–C1). Gender effects were limited.Ligament tests demonstrated expected rate effects. Younger specimens had a higher failure force and stiffness and failed at lower elongations than older specimens from previous studies. Gender effects suggest there may be a difference between male and female properties, but require further testing to establish greater significance.

Changes in Dynamic Plantar Pressure During Loaded Gait

Lower extremity overuse injuries are detrimental to military readiness. Extremes of arch height and heavy loads carried by military personnel are associated with increased risk for overuse injury. Little is known regarding the impact of load carriage on plantar pressure distributions during gait. The objective of this study was to determine how load carriage affects plantar pressure distributions during gait in individuals with varying arch types. A cross-sectional, repeated-measures design was used for the study. The study was performed at a research laboratory at Fort Sam Houston, Texas. Service members who were healthy and weighing ≥70 kg were enrolled in the study. The participants (97 men, 18 women; mean age=31.3 years, SD=5.6; mean weight=86.0 kg, SD=11.0) were categorized as having high-, normal-, or low-arched feet on the basis of published cutoff values for the arch height index. Plantar pressure measurements were obtained with the use of an in-shoe pressure measurement system while participants wore combat boots and walked on a treadmill under 3 loaded conditions (uniform, 20-kg load, and 40-kg load). Maximal force (MaxF) and force-time integral (FTI) were assessed with the use of a 9-sector mask to represent regions of the foot. A 3 × 3 repeated-measures analysis of variance was used for analysis across the levels of load and arch type. A significant interaction existed between arch type and load for MaxF and FTI in the medial midfoot, with greater force in low-arched feet. In the medial forefoot, MaxF and FTI were greatest in high-arched feet across all load conditions. In the great toe region, low-arched and normally arched feet had greater MaxF and FTI. The relative distribution of FTI increased proportionately in all regions of the foot regardless of arch type for all load conditions. The influence of fatigue, greater loads, and different walking speeds was not assessed. Regardless of arch type, increases in load did not alter the relative distribution of force over the plantar foot during gait. Participants with high-arched feet had greater force in the medial forefoot region, whereas those with normally arched or low-arched feet had greater force in the great toe region, regardless of load. These differences in force distribution may demonstrate different strategies to generate a rigid lever during toe-off.

Effect of elastin digestion on the quasi-static tensile response of medial collateral ligament

Elastin is a structural protein that provides resilience to biological tissues. We examined the contributions of elastin to the quasi-static tensile response of porcine medial collateral ligament through targeted disruption of the elastin network with pancreatic elastase. Elastase concentration and treatment time were varied to determine a dose response. Whereas elastin content decreased with increasing elastase concentration and treatment time, the change in peak stress after cyclic loading reached a plateau above 1 U/ml elastase and 6 h treatment. For specimens treated with 2 U/ml elastase for 6 h, elastin content decreased approximately 35%. Mean peak tissue strain after cyclic loading (4.8%, p ≥ 0.300), modulus (275 MPa, p ≥ 0.114) and hysteresis (20%, p ≥ 0.553) were unaffected by elastase digestion, but stress decreased significantly after treatment (up to 2 MPa, p ≤ 0.049). Elastin degradation had no effect on failure properties, but tissue lengthened under the same pre-stress. Stiffness in the linear region was unaffected by elastase digestion, suggesting that enzyme treatment did not disrupt collagen. These results demonstrate that elastin primarily functions in the toe region of the stress-strain curve, yet contributes load support in the linear region. The increase in length after elastase digestion suggests that elastin may pre-stress and stabilize collagen crimp in ligaments.

The effect of shoe toe box shape and volume on forefoot interdigital and plantar pressures in healthy females

BackgroundIll-fitting footwear can be detrimental to foot health with the forefoot being an area for most discomfort. Studies on footwear have primarily examined sports or orthopaedic prescription shoes and little is known about the effects that everyday flat shoes have on the forefoot. The aim of this study was to investigate the effect of toe box shape in a popular slip-on pump on dorsal and plantar pressures with particular interest around the forefoot in a healthy female population.MethodA convenience sample of 27 female participants with no known foot pathologies was recruited. After assessment of foot size, plantar foot pressure and interdigital pressures were recorded for each of the 3 different toe box styles; round, square and pointed. Participants walked at a self-selected speed over a 10 m walkway whilst wearing each of the 3 styles of shoe and also whilst barefoot. Processed and analysed data extracted included peak pressure, time to peak pressure, contact time and pressure time integral. ANOVA and Freidman analysis was used to test for statistical significance.ResultsShoes with a round toe showed least pressure around the medial aspect of the toes whilst the pointed shoe had least pressure on the lateral toes. Contact times for the plantar regions were not altered in any shoe condition yet contact around the medial aspect of the toes was highest in the pointed shoe.ConclusionThis study highlights that the shape of the toe box in footwear can significantly influence the amount of pressure applied to the forefoot. Furthermore, the contours of the shoe also have an impact on the contact time and pressure time integral around the forefoot and also the peak plantar pressure in the toe region. The changes observed could be significant in the development of pathology in certain footwear toe box shapes. Consideration should be given to footwear design around the toe box to improve fit and reduce pressure. Further work is required to investigate the effect of toe box shape and volume on a pathological population with pressure related lesions.

Dermatoclyphic Patterns in Angiographically Proven Coronary Artery Disease

Dermatoglyphics is the scientific study of epidermal ridges and their configurations on the palmar region of hand and fingers and plantar region of foot and toes. Against the genetic background of dermatoglyphic patterns and coronary artery disease, the study was undertaken to determine the correlation between them. The present study includes 150 cases of angiographically proven coronary artery disease (CAD) and 150 cases of healthy normal individuals. The palmar prints of both hands were taken on white paper by Ink method as described by Cummins and Midlo. It is noted that there is significant decrease in loops with corresponding increase in whorls in males, (M+F) combined series and left hand of CAD patients. The true palmar pattern is significantly decreased in thenar area in females; third interdigital area in (M+F) combined series and right hand; and fourth interdigital area in left hand of CAD patients. There is significant increase in ‘4’ palmar triradii in males, (M+F) combined series and right hand; and ‘5’ palmar triradii in females with significant decrease in ‘6’ palmar triradii in both sexes and both hands of CAD patients. The mean value of atd angle is significantly increased in males, (M+F) combined series and left hand of CAD patients as compared to the controls. There is no significant correlation in ab ridge count and CAD.

Kinematic changes in patients with double arthrodesis of the hindfoot for realignment of planovalgus deformity

Double fusion (i.e., fusion of the subtalar and talonavicular joint) represents a modification of triple arthrodesis preserving integrity of the calcaneocuboidal joint. Our aims were (1) to evaluate dynamic plantar pressure distribution in patients undergoing double arthrodesis, (2) to obtain a comparison of kinematic changes to healthy feet, (3) to evaluate the influence of radiographic alignment, and (4) to assess functional outcome. Sixteen feet (14 patients) treated by double fusion due to fixed planovalgus deformity were included. Dynamic plantar pressure distribution was assessed using a capacitive pressure platform. Results were compared with a demographically matched control group. Clinical assessment included the American Orthopaedic Foot and Ankle Society (AOFAS) score and radiographic assessment included measurement of talometatarsal, calcaneal pitch, and talocalcaneal (TC) angle on lateral radiographs. Significant differences in plantar pressure distribution were found for maximum force of the hindfoot, midfoot, and big toe region: While the hindfoot and hallux represented decreased load in the double arthrodesis patients, load increased in the midfoot region compared with healthy controls. The lateral talus-first metatarsal-angle increased from -16.3° to -8.2°, and the TC angle decreased from 41.3° to 35.8° (p < 0.05). The pre- and post-operative AOFAS score increased from 37 points (SD, 16.3) to 70 points (SD, 16.7). These results revealed that double arthrodesis represents a reliable method for correction of planovalgus deformity. Compared with healthy feet, force transmission of the midfoot is increased whereas push-off force decreases.

Quantitative Analysis of Head Scatter and Jaw Transmission Correction Factor for Enhanced Dynamic Wedge Fields Using a 2-dimensional Diode Array

Quantitative Analysis of Head Scatter and Jaw Transmission Correction Factor for Enhanced Dynamic Wedge Fields Using a 2-dimensional Diode Array

Specificity of clinical examinations for testing glenohumeral ligament integrity: a computational study

An accurate diagnosis of glenohumeral joint (GHJ) instability is essential for an effective surgical intervention. There is presently no known comprehensive algorithm of clinical tests for the confirmation of the functional integrity of glenohumeral ligaments (GHLs). A validated computational GHL strain analyser was applied to a set of GHJ kinematics data from the literature to simulate 57 different physiological clinical examination manoeuvres. An algorithm that integrates the GHL pre-straining activities at the toe region of the stress–strain curve was developed for the quantification of ligament loading from prevailing strains. This was used to upgrade the strain analyser and applied to produce a matrix of the various GHL loadings and sensitivities during the manoeuvres. The investigation magnified the likely impact of anatomical variations of GHL attachments as possible causes of misdiagnoses during clinical examinations of GHJ dysfunction. This can serve as an assistive guide to ascertain the functional condition of a specific GHL during symptomatic clinical examinations.

The baric probe: a novel long-term implantable intracranial pressure monitor with ultrasound-based interrogation

Prompt diagnosis of shunt malfunction is critical in preventing neurological morbidity and death in individuals with hydrocephalus; however, diagnostic methods for this condition remain limited. For several decades, investigators have sought a long-term, implantable intracranial pressure (ICP) monitor to assist in the diagnosis of shunt malfunction, but efforts have been impeded by device complexity, marked measurement drift, and limited instrumentation lifespan. In the current report, the authors introduce an entirely novel, simple, compressible gas design that addresses each of these problems. The device described herein, termed the "baric probe," consists of a subdural fluid bladder and multichannel indicator that monitors the position of an air-fluid interface (AFI). A handheld ultrasound probe is used to interrogate the baric probe in vivo, permitting noninvasive ICP determination. To assess the function of device prototypes, ex vivo experiments were conducted using a water column, and short- and long-term in vivo experiments were performed using a porcine model with concurrent measurements of ICP via a fiberoptic monitor. Following a toe region of approximately 2 cm H(2)O, the baric probe's AFI demonstrated a predictable linear relationship to ICP in both ex vivo and in vivo models. After a 2-week implantation of the device, this linear relationship remained robust and reproducible. Further, changes in ICP were observed with the baric probe, on average, 3 seconds in advance of the fiberoptic ICP monitor reading. The authors demonstrate "proof-of-concept" and feasibility for the baric probe, a long-term implantable ICP monitor designed to facilitate the prompt and accurate diagnosis of shunt malfunction. The baric probe showed a consistent linear relationship between ICP and the device's AFI in ex vivo and short- and long-term in vivo models. With a low per-unit cost, a reduced need for radiography or CT, and an indicator that can be read with a handheld ultrasound probe that interfaces with any smart phone, the baric probe promises to simplify the care of patients with shunt-treated hydrocephalus throughout both the developed and the developing world.

The effects of ligamentous injury in the human lower cervical spine

Damage is often sustained by the anterior longitudinal ligament (ALL) and ligamentum flavum (LF) in the cervical spine subsequent to whiplash or other cervical trauma. These ligaments afford substantial cervical stability when healthy, but the ability of the ALL and LF to stabilize the spine when injured is not as conclusively studied. In order to address this issue, the current study excised ALL and LF tissues from cadaveric spines and experimentally simulated whiplash-type damage to the isolated ligaments. Stiffnesses and toe region lengths were measured for both the uninjured and damaged states. These ligamentous mechanical properties were then inputted into a previously-validated finite element (FE) model of the cervical spine and the kinematic effects of various clinically relevant combinations of ligamentous injury were predicted. The data indicated three and five-fold increases in toe region length for the LF and ALL injury variants, respectively. These toe length distensions resulted in FE predictions of supra-physiologic ranges of motion, and these motions were comparable to spines with no ligamentous support. Finally, a set of cadaveric cervical spine ligament-sectioning experiments confirmed the FE predictions and supported the finding that partial injury to the relevant ligaments produces equivalent cervical kinematic signatures to spines that have completely compromised ALL and LF tissues.

Mathematical model of mechanical behavior of micro/nanofibrous materials designed for extracellular matrix substitutes

Electrospun micro/nanofibrous biomaterials are widely used as extracellular matrix substitutes in tissue engineering applications because of their structural and mechanical properties. To explore the influence of microstructure on the mechanical behavior of fibrous material, a mathematical model of the fiber system was developed. The model describes the microstructural properties of a fibrous matrix using a probability density function, and enables study of their mechanical properties. The results from the mathematical model were validated by qualitative comparison with the experimental results of mechanical testing of polystyrene electrospun nanofibrous materials. The analyses show a trend of three-phase load–displacement behavior. Initially, as an increasing number of fibers are recruited for load bearing, the load–displacement curve has a ‘J’-shaped toe region, which is followed by a nearly linear load–displacement curve, in which the number of load-bearing fibers remains nearly steady. Finally, there is a phase when the load–displacement curve descends, indicating failure of the material. The increase in flexibility of the fibrous material makes it stronger, but the randomness of fiber orientation makes the fibrous structure more flexible at the cost of lower strength. The measured mechanical properties of a fibrous matrix were also observed to be dependent on sample size. Therefore, the analyses establish a clear link between the structure and strength of fibrous materials for optimized design and fabrication of fibrous biomaterials with targeted use in tissue engineering, regenerative medicine and drug delivery. The model also establishes a need for standardization of experimental protocols for mechanical characterization of fibrous materials for consistency.

Aggradation and progradation controlled clinothems and deep-water sand delivery model in the Neogene Lake Pannon, Makó Trough, Pannonian Basin, SE Hungary

In the Late Miocene–Early Pliocene Lake Pannon, regression went on for about 6Ma. Sediments arriving from the Alpine–Carpathian source area were partly accumulated on the flat-lying morphological shelf of the lake, whereas other portions of the sediment were passing through to the slope and deposited on the deep basin floor. The height of the slope exceeded 400–500m based on correlated well and seismic data. An extended 3D seismic volume covering the Makó Trough, one of the largest and deepest depressions within the Pannonian Basin, provided an opportunity to study sequences and shelf-margin trajectories generated as a result of continuous slope advancement. The lithology of these shelf, slope and basin centre deposits was inferred from seven well logs and 220m core material.In the Makó Trough the southeastward migrating shelf-margin was formed by alternating aggradational and progradational clinothems. Aggradational clinothems, i.e. aggradation accompanied by subordinate progradation, are characterised by rising shelf-margin trajectories. The shelf built up from inner-shelf to shelf-edge deltaic lobes which compose a few dozen metre thick coarsening-up units. The majority of the sand, however, was transported by effective turbidity currents through leveed channels into the basin, and deposited as thick, extended slope-detached turbidite lobes up to a distance of 30km from the shelf edge. In aggradational clinothems both the shelf and the basin floor accreted vertically. Development of progradational clinothems resulted in horizontal (flat) shelf-margin trajectories. Corresponding reflections toplap at the shelf edge and downlap within a distance of few kilometres from the toe of the slope. The shelf was bypassed, sediments accumulated on the slope and directly at the slope–toe region as small simple lobes. Short-distance transport was the result of clay-poor, non-effective turbidity currents. Consequently, the thickness of coeval basin-centre sediments remained negligible in progradational clinothems.Alternations of rising and horizontal shelf margin trajectories indicate that the climate- and subsidence-controlled lacustrine base-level rose continuously, though at varying rates. Descending trajectories were not observed. It means that base-level drops larger in amplitude than the seismic resolution (20–30m), did not occur during the studied time interval, i.e. at 7–5Ma ago, approximately corresponding to the Messinian age. As a result, major forced-regressive wedges or lowstand fans did not develop. This is in contrast with former stratigraphic models claiming that several 3rd-order sequences, including the intra-Messinian unconformity supposedly induced by hundred metres large lake-level drop, developed in Lake Pannon with significant volume of lowstand deposits as turbidites. Instead, aggradational and progradational clinothems are interpreted as fourth-order transgressive, early and late highstand systems tracts. These incomplete sequences represent less than 100kyr time intervals.Due to climate control both on high rate of sediment supply and the water budget of Lake Pannon, conditions were more favourable for deposition of large volumes of well-developed turbidite systems during base-level rise than during stagnation or minor base-level fall. Therefore, sand delivery to the basin centre was at maximum during the early highstand aggradational stage and at minimum during the late highstand progradational stage. The timing and position of sand accumulation in the Makó Trough of Lake Pannon is different from those predicted by “traditional” sequence stratigraphic considerations.

Comparison of plantar loads during treadmill and overground running

ObjectivesThe objective of this study is to compare plantar loads during treadmill running and running on concrete and grass surfaces. DesignCrossover study design was used in the study. MethodsA total of 16 experienced heel-to-toe runners participated in the study. Plantar loads data were collected using a Novel Pedar insole sensor system during running on the treadmill, concrete, and grass surfaces at 3.8m/s running speed and then analyzed. ResultsCompared with running on the two other surfaces, treadmill running showed a lower magnitude of maximum plantar pressure and maximum plantar force for the total foot, maximum plantar pressure at two toe regions, and maximum plantar force for the medial forefoot region and two toe regions (p<0.0017). Treadmill running also showed a longer absolute contact time at two toe regions compared with running on the other two surfaces (p<0.0017). ConclusionsTreadmill running is associated with a lower magnitude of maximum plantar pressure and a lower maximum plantar force at the plantar areas. These results suggest that the plantar load distribution in treadmill running is not the same as the plantar load distribution in running on overground surfaces. Treadmill running may be useful in early rehabilitation programs. Patients with injuries in their lower extremities may benefit from the reduction in plantar loads. However, the translation to overground running needs investigation.

Response corridors for the medial–lateral compressive stiffness of the human arm: Implications for side impact protection

The biofidelity of side impact anthropomorphic test devices (ATDs) is crucial in order to accurately predict injury risk of human occupants. Although the arm serves as a load path to the thorax, there are currently no biofidelity response requirements for the arm. The purpose of this study was to characterize the compressive stiffness of male and female arms in medial–lateral loading and develop corresponding stiffness response corridors. This was accomplished by performing a series of pendulum tests on 18 isolated post-mortem human surrogate (PMHS) arms, obtained from four male and five female surrogates, at impact velocities of 2m/s and 4m/s. Matched tests were performed on the arm of the SID-IIs ATD for comparison. The arms were oriented vertically with the medial side placed against a rigid wall to simulate loading during a side impact automotive collision. The force versus deflection response data were normalized to that of a 50th percentile male and a 5th percentile female using a new normalizing technique based on initial arm width, and response corridors were developed for each impact velocity. A correlation analysis showed that all non-normalized dependent variables (initial stiffness, secondary stiffness, peak force, and peak deflection) were highly correlated with the initial arm width and initial arm circumference. For both impact velocities the PMHS arms exhibited a considerable amount of deflection under very low force before any substantial increase in force occurred. The compression at which the force began to increase considerably was consistent with the average tolerable medial–lateral arm compression experienced by volunteers. The initial stiffness (K1), secondary stiffness (K2), peak force, and peak deflection were found to significantly increase (p<0.05) with respect to impact velocity for both the non-normalized and normalized PMHS data. Although the response of the SID-IIs arm was similar to that of the female PMHS arms for both impact velocities, the SID-IIs arm did not exhibit a considerable toe region and therefore did not fall within the response corridors for the 5th percentile female. Overall, the results of the current study could lead to improved biofidelity of side impact ATDs by providing valuable data necessary to validate the compressive response of the ATD arm independent of the global ATD thoracic response.

Der Einfluss einer Schuheinlage aus Karbonauf die plantare Druckverteilung im Radschuh

Several equipment interventions like optimizing seat position or optimizing shoe/insole/pedal interface are suggested to reduce overuse injury in cycling. Data analyzing clinical or biomechanical effects of those interventions is sparse. Foot orthoses out of carbon fiber are one possibility to alter the interface between foot and pedal. The aim of this study was therefore to analyze plantar pressure distribution in carbon fiber foot orthoses in comparison to standard insoles of commercially available cycling shoes. 11 painfree triathletes (Age: 29±9, 1.77±0.04 m, 68±5 kg) were tested on a cycle ergometer at 60 and 90 rotations per minute (rpm) at workloads of 200 and 300 Watts. Subjects wore in randomized order a cycling shoe with its standard insole (control condition CO) or the shoe with carbon fiber foot orthoses (Condition CA). Mean peak pressure out of 30 movement cycles were extracted for the total foot and specific foot regions (rear, mid, fore foot (medial, central, lateral) and toe region). Three-factor ANOVAs (factor foot orthoses, rpm, workload) for repeated measures (α = 0.05) were used to analyze the main question of a foot orthoses effect on peak in-shoe plantar pressure. Peak pressures in the total foot were in a range of 70-75 kPa for 200 Watts (W) (300 W: 85-110 kPa). The carbon fiber foot orthoses reduced peak pressures by -4,1% compared to the standard insole (p = 0,10). In the foot regions rear (-16,6 %, p < 0.001), mid (-20,0 %, p < 0.001) and fore foot (-5.9 %, p < 0.03) CA reduced peak pressure compared to CO. In the toe region, peak pressure was higher in CA (+16,2 %) compared to CO (p < 0,001). The lateral fore foot showed higher peak pressures in CA (+34 %) and CO (+59 %) compared to medial and central fore foot. Carbon fiber can serve as a suitable material for foot orthoses manufacturing in cycling. Plantar pressures do not increase due to the stiffness of the carbon. Individual customization may have the potential to reduce peak pressure in certain foot areas.