Cycle Kinematics Research Articles

Detection of Horse Locomotion Modifications Due to Training with Inertial Measurement Units: A Proof-of-Concept.

Detecting fatigue during training sessions would help riders and trainers to optimize their training. It has been shown that fatigue could affect movement patterns. Inertial measurement units (IMUs) are wearable sensors that measure linear accelerations and angular velocities, and can also provide orientation estimates. These sensors offer the possibility of a non-invasive and continuous monitoring of locomotion during training sessions. However, the indicators extracted from IMUs and their ability to show these locomotion changes are not known. The present study aims at defining which kinematic variables and indicators could highlight locomotion changes during a training session expected to be particularly demanding for the horses. Heart rate and lactatemia were measured to attest for the horse’s fatigue following the training session. Indicators derived from acceleration, angular velocities, and orientation estimates obtained from nine IMUs placed on 10 high-level dressage horses were compared before and after a training session using a non-parametric Wilcoxon paired test. These indicators were correlation coefficients (CC) and root mean square deviations (RMSD) comparing gait cycle kinematics measured before and after the training session and also movement smoothness estimates (SPARC, LDLJ). Heart rate and lactatemia measures did not attest to a significant physiological fatigue. However, the statistics show an effect of the training session (p < 0.05) on many CC and RMSD computed on the kinematic variables, indicating a change in the locomotion with the training session as well as on SPARCs indicators (p < 0.05), and revealing here a change in the movement smoothness both in canter and trot. IMUs seem then to be able to track locomotion pattern modifications due to training. Future research should be conducted to be able to fully attribute the modifications of these indicators to fatigue.

Hopscotching jellyfish: combining different duty cycle kinematics can lead to enhanced swimming performance

Jellyfish (Medusozoa) have been deemed the most energy-efficient animals in the world. Their bell morphology and relatively simple nervous systems make them attractive to robotocists. Although, the science community has devoted much attention to understanding their swimming performance, there is still much to be learned about the jet propulsive locomotive gait displayed by prolate jellyfish. Traditionally, computational scientists have assumed uniform duty cycle kinematics when computationally modeling jellyfish locomotion. In this study we used fluid-structure interaction modeling to determine possible enhancements in performance from shuffling different duty cycles together across multiple Reynolds numbers and contraction frequencies. Increases in speed and reductions in cost of transport were observed as high as 80% and 50%, respectively. Generally, the net effects were greater for cases involving lower contraction frequencies. Overall, robust duty cycle combinations were determined that led to enhanced or impeded performance.

Effect of Training With the Hybrid Assistive Limb on Gait Cycle Kinematics After Total Knee Arthroplasty.

IntroductionReportedly, wearable robots, such as the hybrid assistive limb (HAL), are effective in the functional recovery of various locomotor disabilities, including disrupted walking, restricted range of motion, and muscle weakness. However, the effect of walking exercises with a HAL on the kinematic and kinetic variables of lower limb joint function is not yet fully understood. Therefore, the purpose of this study was to elucidate the effect of HAL on the kinematic and kinetic variables of lower limb function in patients 5 weeks after total knee arthroplasty (TKA).Materials and MethodsNine patients (ten knees) in the HAL training group and nine patients (nine knees) in the control group underwent TKA. HAL training was initiated 1–5 weeks after TKA, and general rehabilitation was performed in the control group. Gait analysis was performed on each patient using a motion analysis system at 5 weeks after TKA. We compared the effects of the joint angles of the walking cycle between groups, and investigated the effect of the walking cycle’s joint angles on step length.ResultsIn the HAL group, the odds ratio of hip extension was as large as 1.741, while that of knee swing was as large as 1.501. These 2 variables were significant between the 2 groups. Knee swing and varus significantly affected step length.ConclusionsOur results suggest that training by wearing HAL after TKA increased the mobility of the knee and hip joints during early postoperative walking, and that walking ability was improved by increasing the step length.

A Mixed Elasto-Hydrodynamic Lubrication Model for Wear Calculation in Artificial Hip Joints

The aim of this paper was to propose a novel in silico mixed elasto-hydrodynamic lubrication model with the purpose of wear prediction in Total Hip Replacements (THRs). The model considers the progressive wear contribution in the calculation of the meatus filled by the non-Newtonian synovial fluid. The results were referred to the gait cycle kinematics, calculated by using musculoskeletal multibody software, while the loading was assumed by literature in vivo measurements. The simulations allow evaluating the fluid and the contact pressure fields and the acetabular cup wear over the time. The results were obtained considering a Ultra High Molecular Weight PolyEthylene, UHMWPE, cup and were compared with results from the literature, showing a good agreement in terms of total volume wear of the cup.

Variation in human gape cycle kinematics and occlusal topography.

This study tested hypotheses relating intraspecific variation in occlusal morphology and intraspecific variation in jaw movements during feeding. Gape cycle kinematic variation was hypothesized to correlate with gape cycle number within a chewing sequence as well as with food toughness and stiffness. Gape cycle kinematic variation was also hypothesized to correlate with variation in occlusal area, slope, and volume. Twenty-six adult human subjects chewed four foods with varying material properties while their jaw movements were recorded using three-dimensional coordinates of facial markers captured with a Vicon camera system. Post-canine occlusal morphology of each subject was quantified in ArcGIS using dental topographic analysis of dental casts. Gape cycle duration did not vary with gape cycle number, food toughness, or food stiffness. Gape cycle vertical and lateral displacement correlated negatively with gape cycle number, while foods with higher toughness and Young's modulus had greater jaw vertical and lateral displacement. Subjects with steeper occlusal slopes had longer gape cycle durations and greater amounts of vertical displacement during the slow closing phase of the gape cycle. The results suggest that gape cycle durations are relatively consistent despite changes in food properties and gape cycle number, while occlusal slope affects gape cycle duration and vertical displacement during inferred occlusal contact. However, gape cycle number and bolus properties explain greater amounts of kinematic variation than does occlusal morphology.

Normal knee gait kinematics: Describing a normal cohort and illustrating differences between genders

Introduction Gait analysis has been extensively studied by many different disciplines using various methods. Despite numerous attempts to understand the “normal” gait cycle, our current body of knowledge is insufficient to allow us to model normal locomotion in a clinically relevant manner. The primary objective of our study was to characterize normal knee3D kinematics during treadmill gait using the KneeKG™ apparatus. Materials and methods Ninety-five patients, 52 females and 43 males, were recruited to participate in our study. Each patient completed the KOOS and SF-12 questionnaires, underwent a KneeKG™ examination, and had full-length weightbearing (FLWB) x-rays. We analyzed the results of the questionnaires, generated gait cycle 3D kinematics (sagittal, transverse, and frontal plane), and measured clinically relevant angles on the FLWB x-rays. Furthermore, we compared knee kinematics between men and women and between the right and left knees of the same patient. We also attempted to find a correlation, using Pearson correlation statistics, between the hip-knee-ankle angle (HKA) and the frontal plane kinematic. Results Average age of our cohort was 36.1 years (SD: 13.3). Our cohort had scores superior to 98 in all five subsections of the KOOS questionnaire. Knee gait cycle kinematics in all planes was similar to what has been reported in the literature. When comparing men and women, significant differences were found in the sagittal motion and transverse rotation planes and in the entirety of the gait cycle in the frontal plane. When comparing the right and left knees, significant differences were only found in the frontal plane. No meaningful correlations could be made between the HKA angle and abduction. Discussion – conclusion As three-dimensional analysis of human gait progressively becomes a clinically useful tool in musculoskeletal diseases, an understanding of normal gait as well as a creation of a normal gait data bank is essential. We believe the results of our study contribute to understanding the kinematics of the gait cycle and foster the notion that cohorts should be divided for gender to account for gait differences in the frontal plane.

The influence of sitting posture on mechanics and metabolic energy requirements during sit-skiing: a case report

Several different sitting postures are used in Paralympic cross-country sit-skiing. The aim of this study was to evaluate the impact of sitting posture on physiological and mechanical variables during steady-state double-poling sit-skiing, as well as to determine how seat design can be improved for athletes without sufficient trunk control. Employing a novel, custom-designed seat, three trunk positions were tested while performing double-poling with submaximal oxygen consumption on an ergometer. Cycle kinematics, pole forces, and oxygen consumption were monitored. The athlete performed best, with longer cycle length and less pronounced metabolic responses, when kneeling with the trunk resting on a frontal support. For this case, a forward leaning trunk with knees below the hip joint was interpreted as most optimal, as it showed lower oxygen consumption and related parameters of performance during cross-country sit-skiing. Further investigations should examine whether such improvement is dependent on the level of the athlete’s handicap, as well as whether it is also seen on snow.

An Assessment of Bamboo as a Potential Low-Cost Material for Exoskeleton Design in Normal Walking

Background: Exoskeletons are mechanical devices used in rehabilitation to enhance human joint movements for individuals suffering from debilitating neurological or limb pathologies lacking sufficient strength, power, torque, and endurance. The cost for standard exoskeletons used for gait rehabilitation and mobility assistance is ridiculously high. This has made such assistive devices, which could impact the quality of life of individuals with disability unattainable. Objective: The aim is to evaluate four natural materials with the hope to replace the currently used duralumin and thereby reduce the cost of exoskeleton. Methods: A two-step analyses process was utilized. First, gait cycle kinematics of normal walking was analyzed and used to determine the minimum loading requirements for the replacement material. The information provided the basis for the assessment of the mechanical properties of four natural construction materials, fir, pine, oak and bamboo used in this study. Secondly, Granta CES Selector software was used to assess the cost, mechanical properties and viability of these natural materials with the view of replacing duralumin with them. Results: Analysis of gait cycle kinematics showed that the energy expenditure and loading requirement for walking was highest at mid-stance. All the four natural materials studied satisfied strength and elasticity requirements as dictated by duralumin and the gait analysis. However, bamboo exhibits additional excellent characteristics, such as lightweight, bending, and toughness. Conclusion: Although the four natural materials satisfied the yield strength requirements but only bamboo can be used as replacement material for duralumin. Bamboo with additional characteristics of bending and toughness make it more favorable replacement material for the design of exoskeleton.

Relative contributions of occlusion, maximum bite force, and chewing cycle kinematics to masticatory performance

The purpose of this study was to explore the contributions of occlusion, maximum bite force, and chewing cycle kinematics to masticatory performance. A prospective cross-sectional study was performed on 30 subjects with Class I occlusion. Masticatory performance was measured with the test food Cuttersil (Heraeus Kulzer, South Bend, Ind) and the fractional-sieve technique. Blu-Mousse (Parkell Biomaterials, Farmingdale, NY) bite registrations were used to measure occlusal contact areas. The American Board of Orthodontics occlusal discrepancies were measured on the subjects' dental models. Maximum bite forces were recorded with a custom transducer, and 3-dimensional chewing cycle kinematics were tracked with an opto-electric computer system and Optotrak software (Northern Digital, Waterloo, Ontario, Canada). Masticatory performance was most closely correlated with occlusal contact area, indicating larger contact areas in subjects with better performance. Occlusal contact area and occlusal discrepancies were also related to bite force and chewing cycle kinematics. Maximum bite force was positively related with masticatory performance. Although masticatory performance is related, both directly and indirectly, to a number of morphologic and functional factors, it is most closely related to occlusal factors.

Evaluation of a mixed approach combining stationary and wearable systems to monitor gait over long distance

Thanks to decades of research, gait analysis has become an efficient tool. However, mainly due to the price of the motion capture systems, standard gait laboratories have the capability to measure only a few consecutive steps of ground walking. Recently, wearable systems were proposed to measure human motion without volume limitation. Although accurate, these systems are incompatible with most of existing calibration procedures and several years of research will be necessary for their validation. A new approach consisting of using a stationary system with a small capture volume for the calibration procedure and then to measure gait using a wearable system could be very advantageous. It could benefit from the knowledge related to stationary systems, allow long distance monitoring and provide new descriptive parameters. The aim of this study was to demonstrate the potential of this approach. Thus, a combined system was proposed to measure the 3D lower body joints angles and segmental angular velocities. It was then assessed in terms of reliability towards the calibration procedure, repeatability and concurrent validity. The dispersion of the joint angles across calibrations was comparable to those of stationary systems and good reliability was obtained for the angular velocities. The repeatability results confirmed that mean cycle kinematics of long distance walks could be used for subjects’ comparison and pointed out an interest for the variability between cycles. Finally, kinematics differences were observed between participants with different ankle conditions. In conclusion, this study demonstrated the potential of a mixed approach for human movement analysis.

Masticatory Performance and Chewing Cycle Kinematics—Are They Related?

To compare chewing cycle kinematics of subjects with better and poorer masticatory performance. A cross-sectional study compared masticatory performance, based on the breakdown of the artificial test food Cuttersil, in 30 subjects with Class I occlusion. Individuals with median particle sizes greater and lesser than the median value for the entire sample were categorized as poorer (15) and better (15) performers, respectively. While chewing Cuttersil, three-dimensional jaw movements of subjects were tracked with an optoelectric computer system. Multilevel linear modeling was used to evaluate differences in estimated cycle shape, cycle duration, and maximum excursions, as well as within-subject variation between the two groups. Poorer performers had a significantly longer opening duration (0.274 +/- 0.225 sec vs 0.325 +/- 0.270 sec) than better performers. Poorer and better performers also showed significant differences in cycle shape, including a less horizontal path of closure and more posterior jaw movement in the poorer performers. In addition, poorer performers exhibited significantly more cycle-to-cycle (within-subject) variability in chewing cycle duration, excursive movements, and lateral velocity than did better performers. Poorer performers lacked consistency in their chewing cycles, and their cycle shape differs from that of better performers.

Myths of orthodontic gnathology

D r Beverly McCollum established the Gnathologic Society in 1926. Gnathology is defined as ‘‘the science that treats the biology of the masticatory mechanism as a whole: that is, the morphology, anatomy, histology, physiology, and the therapeutics of the jaws or masticatory system and the teeth as they relate to the health of the whole body, including applicable diagnostic, therapeutic, and rehabilitation procedures.’’ Many gnathologic research endeavors have added much to our knowledge and understanding of the stomatognathic system, particularly those involving chewing (masticatory) kinematics and the early intraoral telemetry studies (to cite only a few). Although originally founded on scientific principles, the application of the valid gnathologic research to clinical practice has moved away from these founding tenets. Modern clinical gnathology (vs university-based gnathologic research) has become, for the most part, a pseudo-science based on mechanistic, perfunctory procedures, and instrumentation. There are many contemporary occlusal institutes that clearly have perverse views on gnathology that are not evidence-based. Dr Lysle Johnston sarcastically stated that ‘‘gnathology is the science of how articulators chew.’’ In the 1970s, Roth formally introduced the classic principles of clinical gnathology to orthodontics (orthodontic gnathology). The notions and considerations of modern orthodontic gnathology are not based on principles of science and do not correspond to contemporary evidence-based thinking. There might not be a unified orthodontic gnathologic view, but it seems that the one established by Roth is by far the most notable.

Cluster analysis: A useful data reduction technique in simultaneous kinematics–kinetics–plantar pressure analysis

s of the SIAMOC 2008 Congress / Gait & Posture 29S (2009) e1–e31 e22 Cluster analysis: A useful data reduction technique in simultaneous kinematics–kinetics–plantar pressure analysis Z. Sawacha *, A. Guiotto , G. Guarneri , G. Cristoferi , A. Avogaro , C. Cobelli 1 Department of Information Engineering, University of Padova, Padova, Italy Department of Clinical Medicine & Metabolic Disease, University Polyclinic, Padova, Italy Introduction: To accurately evaluate the extent of diabetics gait deviations from normal gait, it is important to consider not only how each feature of the gait pattern has changed but also how the relationship between the features changed. In order to improve diabetic foot prevention treatments it is important to establish the correlation that exists between gait variables and foot biomechanics alterations. Least but not less important, the large amount of variables obtained in kinematics–kinetics and plantar pressure (PP) analysis need to be reduced in order to be clinically useful. Thus, in the light of these premises, the aims of this studywill be to apply cluster analysis either to agglomerate the patients with common gait deviations in the same cluster or to find which gait parameters characterizes the pathology. So far patients can be classified relatively to their gait pattern alterations and specific prevention protocols developed. Methods: Kinematics, kinetics and PP data of 35 subjects (14 normal (C), 9 diabetics (D), 12 diabetic neuropathics (DN)) have been collected by means of 6 cameras BTS Sr.l. motion capture system (60–120 Hz) synchronized with 2 Bertec force plates (FP4060-10) and 2 plantar pressure plates (Imago). A 3D foot markerset was used and gait and posture analysis performed [1]. Five homogeneous groups were created, in order to compare subjects with the same type of foot: cavus foot (CF), CF and valgus (V) heel, CF and normal heel, CF and normal hallux, CF and V hallux. 3D subsegments forces, plantar pressure, contact surface and joint rotation angles were calculated [1] and each group normative bands (nb) created (mean 1SD). COP pattern was analyzed in both anteroposterior (AP) and mediolateral direction and its integral calculated. Hierarchical and k-mean cluster analysis were performed: each one starting with all of the observations in one cluster and then proceeding to split them into smaller clusters. Results: k-Means cluster analysis [2] was successfully used as a data reduction method. Each group significant variables were identified as the ones that successfully agglomerate the same type of subjects (normal, diabetics, neuropathics) relatively to the same type of foot carachteristics. Concerning the kinematics variables these were: midfoot-hindfoot (M-H) prono-supination and abdadduction (AA) together with forefoot-midfoot (F-M) AA in cavus foot and hallux valgus groups, F-M dorsi-plantarflexion (DP) in cavus foot and valgus hallux groups, M-H DP in cavus foot group. Concerning kinetics and PP variables these were: the F contact surface, Mmean and peak pressure, F vertical, anteroposterior and mediolateral force in cavus foot and hallux valgus groups (Fig. 1). Fig. 1. The bar plot displays the percentage of subjects (blue C, red D, green DN) belonging to each group that have been agglomerated in the same cluster by the specific gait parameter, respectively: midfoot-hindfoot prono-supination angle (1), forefoot-midfoot dorsi-plantarflexion angle (2), forefoot-midfoot abductionadduction angle (3), during one gait cycle (kinematics analysis), forefoot contact surface (4) during stance phase (PP). Discussion: Cluster analysis allowed to classify subjects according to their gait alterations, and agglomerated correctly each group specific gait parameters. Therefore this variables subdivision can be used in planning prevention treatments. A larger sample of subject is being investigated.

Effects of bolus size and hardness on within-subject variability of chewing cycle kinematics

This study analysed how bolus hardness and size affect within-subject variability of chewing cycle kinematics. Two independent prospective studies were performed; both tracked chin movements using an optoelectronic recording system. Computer programs identified each subject's ten most representative cycles, and multilevel modelling procedures were used to estimate variances. One study evaluated 38 subjects who chewed 1, 2, 4 or 8 g of gum presented in random order. The second study evaluated 26 subjects who chewed approximately 2.5 g of harder (670 g) or softer (440 g) gum, also presented in random order. In terms of bolus size, the 2 g and 1 g boluses produced the least and greatest relative within-subject variability, respectively; the largest differences were found for cycle duration and excursions. Within-subject variability when chewing the harder gum was consistently greater than when chewing the softer gum, except for lateral movement towards the balancing side. Because bolus hardness and bolus size influence within-subject variability differently, they must be taken into consideration when designing experiments to study masticatory kinematics. We conclude that a 2 g bolus of soft gum should be used in studies of chewing cycle kinematics in order to reduce within-subject variability and increase statistical power.

An Integrated Knowledge Base for Modelling and Predicting Vehicle Real-world Emissions as a Function of Driving Behaviour Kinematics

A multivariate modelling approach was developed by Istituto Motori to model and predict vehicle real-world emissions. Complex driving kinematics is represented by two blocks of variables, which require the development of a hierarchical multiblock emission model, where the two blocks of variables represent overall and instantaneous features of each driving cycle associated to a trip. The multiblock model was applied to analyze and model emissions of the large database built in the ARTEMIS project. In this database we collected emission measurements performed in European laboratories relative to real driving cycles which are statistically representative of many European traffic/road conditions from congested to rush-hour traffic in urban, rural and highway roads. Data concern a varied fleet of vehicles differing in technology and class. To develop a tool useful for mobility analysts for traffic environmental impact assessment, a knowledge base was envisaged to integrate the data warehouse and the model base to build a user interface for driving cycle kinematics and emission analysis. In this paper the modelling approach is presented together with overall emission and driving kinematics characterization based on experimental results, as well as functional analysis of the knowledge base structure and the information tool.

Diarthrodial joint contact models: finite element model development of the human hip

The demands associated with modeling geometrically complex anatomic structures often limit the utility of musculoskeletal finite element (FE) analyses. Automated meshing routines typically rely on the use of tetrahedral elements. Hexahedral elements, however, often outperform tetrahedral elements, namely during contact analyses. Hence, a need exists for a preprocessor geared towards automated hexahedral meshing of biologic structures. Two meshing schemes for finite element mesh development of the human hip are presented: (1) a projection method, coupled with a surface smoothing algorithm, has been applied to accommodate the near spherical nature of the femoral head articular cartilage surface, while (2) a technique termed the preferential method was developed to mesh the acetabulum. The latter technique benefits from a user traced bound of the articular surface. High-quality, three-dimensional continuum models, consisting solely of hexahedral elements, were generated for the femoral head and the acetabulum. To check the validity of the meshing routines, a transient deformable–deformable contact finite element analysis was carried out. Gait cycle kinematics and kinetics from the weight-bearing stance phase were considered. The contact pressure (1.74 MPa) was in agreement with the values reported in the literature.

Chewing cycle kinematics of subjects with deepbite malocclusion

The notion that chewing cycle shape and cycle dynamics differ between subjects with and without malocclusion is largely based on qualitative studies that combined various types of malocclusion. The purpose of this prospective study was to determine whether chewing cycle kinematics of untreated young adults with deepbite malocclusion differ from those with normal occlusion. Twenty-three deepbite subjects (>50% overbite) and 24 controls with normal occlusion chewed gum (right side only) while their jaw movements were recorded at 100 Hz by using an optoelectric jaw tracking system. Differences in cycle duration between deepbite and control subjects were small and not significant (P >.05). The deepbite subjects showed significantly (P <.05) less maximum inferior excursion (7.7 vs 9.0 mm) and significantly greater maximum posterior excursion (5.1 vs 4.0 mm) than subjects with normal occlusion. In addition, the deepbite subjects had significantly smaller maximum vertical velocities than subjects with normal occlusion (49.2 vs 60.8 mm per second). Deepbite subjects also showed significantly (P <.05) less cycle-to-cycle variability in maximum velocities and excursions to the balancing side but significantly (P <.05) greater variability in cycle duration and maximum posterior excursions. A deepbite malocclusion alters the shape of chewing cycles and the consistency of chewing cycle kinematics.

A direct comparison of patient and force-controlled simulator total knee replacement kinematics

The need to critically evaluate the efficacy of current total knee replacement (TKR) wear testing methodologies is great. Proposed international standards for TKR wear simulation have been drafted, yet their methods continue to be debated. The “gold standard” to which all TKR wear testing methodologies should be compared is measured in vivo TKR performance in patients. The current study compared patient TKR kinematics from fluoroscopic analysis and simulator TKR kinematics from force-controlled wear testing to quantify similarities in clinical ranges of motion and contact bearing kinematics and to evaluate the proposed ISO force-controlled wear testing methodology. The treadmill walking kinematics from eight well-functioning, 13 month average post-op patients were compared to the 2 million cycle interval walking cycle kinematics from a force-controlled (Instron/Stanmore Knee Joint Simulator, Instron, Canton, MA) knee simulator using identical implant designs (Natural Knee II, Standard Congruent, Zimmer, Warsaw, IN). The in vivo and simulator data showed good agreement in kinematic patterns and ranges of clinical motion. Tribologically the data sets showed similar contact pathway ranges of motion and wear travel distances per cycle. Surgical and simulator alignments of the implant systems were determined to be a contributing factor in observed kinematic differences. This study's statistical findings offer supporting evidence that the simulation of in vivo walking cycle wear kinematics can be accurately reproduced with a force controlled testing methodology.

Effect of an auditory cue on chewing cycle kinematics

This study analysed the systematic and random effects of a rhythmic auditory cue on chewing cycle kinematics. The chin movements of 25 subjects (19-35 years of age) with normal class I occlusion were recorded at 100Hz (Optotrak) Northern Digital) during two natural gum chewing (2.5 g) sequences to determine the chewing rate of each subject. Another sequence was recorded with the subjects chewing at their natural rate following an audible cue. Multilevel modeling procedures were used to evaluate differences between natural chewing with and without an audible cue. Differences were found between experimental conditions for excursions, velocities and cycle shape. When chewing with the audible cue velocities were slower and there was less excursion of the chin marker, with the exception of initial lateral movements toward the balancing side. No differences in between-subject variability were found when chewing with or without an audible cue. Within-subject variability was 44% smaller for total cycle duration and 53% smaller for total 3D excursion when chewing with the auditory cue. Chewing at one's normal rate while following an auditory cue produces more consistency in chewing cycle kinematics. This method may be applicable, with some limitations, to reduce within-subject variability in chewing cycle kinematics.

Plantar pressure distribution in patients with neuropathic diabetic foot.

To describe the plantar pressure distribution in a selected group of patients with diabetic foot and to highlight their alterations in gait cycle, which follow the involvement of the foot in systemic diabetic neuropathy. Ten patients with diabetic foot due to insulin dependent diabetes mellitus (IDDM) were studied. Gait cycle kinematics were video-recorded, both in frontal (AP view) and in sagittal (LL view) planes. Plantar pressure measurements+ APview+LLview were synchronized and compared to a computer-graphic generated skeletal model of the foot. In diabetic neuropathic patients, there was a prolonged interval between heel strike and toe-off with respect to normal controls. A limited motion, quite close to frank rigidity, affecting the mid-tarsal, sub-talar and ankle joints was noted. There was an early transfer of load from rear to front-foot. Shear stresses appeared. Metatarsal heads were overloaded both in mag-nitude and in time. Areas of overload present in the static plantar pressure measurement correlated poorly with areas of over-load in dynamic plantar pressure measurement and areas where ulceration was present. Prolonged duration of the gait cycle and shear stresses characterize the plantar pressure pattern of diabetic neuropathic patients. Furthermore, results suggest that static plantar pressure measurement has no clinical correlation with areas where ulcerations are present. (Journal of Applied Biomaterials and Biomechanics 2005; 3: 61-4).