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The paper is focused on the foot-knee mechanism and changes in the foot rocker in gait cycle. Three CP children were selected from a group participating in a three year individual physiotherapy program supplemented with exercises on the active balance saddle as a substitute of hippotherapy. Each kind of session was administered 2-3 times a week. Gait of these children was videotaped after every period of 6 months of rehabilitation. SIMI Motion system was used for data collection. The children presented in the paper are: No. 1, 10.5 years old (at the last session) with spastic diplegia classified on level 3 with GMFCS who underwent tendo-Achilles lengthening (TAL), No. 8, 4.6 years old, with spastic hemiplegia classified on level 4 with GMFCS who walked with anterior walker, No. 10, 10.7 years old, with spastic hemiplegia classified on level 1 with GMFCS. Step frequency, knee-foot angle relationship and especially the foot mechanism were analyzed. Subject 10 walked with a frequency of 120 step/min and his velocity of the 1st and 3rd foot rocker was 3-5 and 5-8 rad/s, respectively. His walking ability didn't change much over the entire period. Subject 1 began the program after TAL. There was no dorsal flexion at IC, however a very slight improvement of the 1st foot rocker was noticed at the two last video sessions. The velocity of 3rd rocker was 3-5 rad/s. The youngest subject (8) at the first video session could walk with assistance, stepping on flat foot, and showed 3rd rocker with velocity 3 rad/s. Thereafter he walked with walker, stepping on forefoot almost through the entire MSt and TSt. The 3rd rocker was weak with velocity about 1 rad/s. At the last (6th) session a slight improvement was recorded.

Human intra limb gait kinematics were analyzed via statistical and structural pattern recognition methods to determine the role of relative timing of limb segments within and between modes of gait. Five experienced runners were filmed while walking (3-6 km/hour) and running (8-12 km/hour) on a motor driven treadmill. Kinematic data consisted of relative timing of the four phases of the Philippson step cycle and intersegmental limb trajectories, determined from angle-angle diagrams. Despite marked decreases in absolute time durations within gaits remained constant over the speeds which were studied. Although a 2-fold increase in locomotor speed occurred in walking and a 1.5-fold speed increase occurred within running, the percentage of time spent in each of the Philippson phases was not significantly changed. However, significant differences in the time percentages and sequences of the step cycle phases were found between walking and running. Correlations between limb segment trajectories occurring in the different gaits showed strong coherence for overall step cycle patterns, but within step cycle phases and across speeds, selective phases displayed little correspondence.

Perceived slipperiness rating (PSR) has been widely used to assess walkway safety. In this experiment, 29 participants were exposed to 5 floor types under dry, wet and glycerol conditions. The relationship between their PSR and objective measurements, including utilized coefficient of friction (UCOF), gait kinematics and available coefficient of friction (ACOF), was explored with a regression analysis using step-wise backward elimination. The results showed that UCOF and ACOF, as well as their difference, were the major predictors of the PSR under wet and glycerol conditions. Under wet conditions, the participants appeared to rely on the potential for foot slip to form their PSR. Under glycerol conditions, some kinematic variables also became major predictors of PSR. The results show how different proprioceptive responses and ACOF contributed to the prediction of PSR under different surface conditions.

Kinematics and electromyographic (EMG) activity were recorded in seven normal women during walking at slow, free, and fast speeds. Speed-related differences were found in the stride dimensions, temporal components, and most of the simultaneous displacement patterns of body segments measured. For most of the muscles tested, the amplitude of normalized EMG activity decreased as walking speed decreased. The findings emphasize the importance of accounting for the effect of speed itself on measurements of gait.

A complete gait analysis was performed on six children with below-knee amputations to determine the kinematics and kinetics of amputee gait in children. A relatively new method of analysis--the inverse dynamic relationship--was used to determine the joint moments in the sagittal plane of the joints in the intact limb and the remaining portion of the amputated limb. The joint moments in the sagittal plane of the intact limb in the child amputee were found to be normal or below normal during level walking. From this study, it was concluded that providing a child amputee has a good prosthetic fit, there will be no increased forces across the joints of the intact or amputated limb and consequently no predisposition to premature degenerative arthritis.

The purpose of this preliminary study was to make kinematic comparisons of a recent below-the-knee amputee's (BKA) gait with the gait of normals and an experienced BKA. Kinematic data were collected for four normal children, an experienced BKA child, and a novice BKA child. The results indicated that over time, the novice BKA seemed to approach a pattern more similar to that of the experienced BKA than that of the normal children. The differences in gait could be an appropriate adaptation to the morphological and physiological needs of the BKA subjects, suggesting that attempts to modify the gait of these subjects toward normal patterns might not be in their best interest. >

Standardbred pacers were studied at four different nominated speeds and selected gait kinematics were analysed to determine factors which contribute to pacing speed. A deterministic model is proposed in which pacing speed is a function of stride length and stride timing variables. Stance length and suspension time remained relatively constant over the different pacing speeds. Variables which discriminated best between pacing speeds were suspension length and overlap time. At near maximal speed, the pacers increased speeds with increased stride length. This was attributed to an increased suspension length with little difference in suspension times. A 22 per cent increase in pacing speed resulted in a 13 per cent increase in stride length, 26 per cent increase in suspension distance, 8 per cent increase in stride frequency, 35 per cent and 16 per cent increases in advanced placement and completion times and a 23 per cent decrease in the period of overlap.

Standardbred pacers have been studied under race conditions to describe the gait of the pacer, and to determine relationships between stage of the race, finish order and selected gait kinematics. Overlap increased with the stage of the race while pacing speed decreased marginally for low order pacers and increased for high order finishers. High order finishing pacers appear to have greater stance and stride lengths than do low order finishers. Pacers could be separated into low order and high order groups on the basis of their movement patterns. High order pacers exhibited greater ranges of limb motion than did low order finishers.

This paper presents a novel functional electrical stimulation paradigm to generate locomotion in paraplegic patients. We propose a closed-loop surface functional electrical stimulation (sFES) of 16 lower-limb muscles to produce all subphases of the gait. The reproduction of cyclic and coordinated joint-movements is a challenge, especially if synchronic and synergic lower-limbs muscular contraction is considered. This paper presents the implementation and validation of a sFES closed-loop position control and the pilot clinical tests with a chronic, motor complete (ASIA B) SCI patient. We demonstrate that the patient can safely use our setup to produce a physiologically correct gait with minimal external help. The implemented sFES-gait training was beneficial to see an improvement in gait kinematics. The integration of the proposed setup with a neurorehabilitation protocol has the potential to become a valuable locomotion therapy for SCI patients.

Musculoskeletal models represent a powerful tool to gain knowledge on the internal forces acting at the joint level in a non-invasive way. However, these models can present some errors associated with the level of detail in their geometrical representation. For this reason, a thorough validation is necessary to prove the reliability of their predictions. This study documents the development of a generic musculoskeletal model and proposes a working logic and simulation techniques for identifying specific model features in need of refinement; as well as providing a quantitative validation for the prediction of hip contact forces (HCF). The model, implemented in the AnyBody Modeling System and based on the cadaveric dataset TLEM 2.0, was scaled to match the anthropometry of a patient fitted with an instrumented hip implant and to reproduce gait kinematics based on motion capture data. The relative contribution of individual muscle elements to the HCF and joint moments was analyzed to identify critical geometries, which were then compared to muscle magnetic resonance imaging (MRI) scans and, in case of inconsistencies, were modified to better match the volumetric scans. The predicted HCF showed good agreement with the overall trend and timing of the measured HCF from the instrumented prosthesis. The average root mean square error (RMSE), calculated for the total HCF was found to be 0.298*BW. Refining the geometries of the muscles thus identified reduced RMSE on HCF magnitudes by 17% (from 0.359*BW to 0.298*BW) over the whole gait cycle. The detailed study of individual muscle contributions to the HCF succeeded in identifying muscles with incorrect anatomy, which would have been difficult to intuitively identify otherwise. Despite a certain residual over-prediction of the final hip contact forces in the stance phase, a satisfactory level of geometrical accuracy of muscle paths has been achieved with the refinement of this model.

This work proposes the implementation and validation of a new sensor fusion strategy based on force sensors and LRF (Laser Range Finder) to control a robotic walker. This approach combines user information about forearm reaction forces and gait kinematics from the legs scanning localization, to develop a more natural, safer and adaptable human-walker interaction. The work was carried out in four phases. First, a robotic walker platform was developed and the sensor subsystems were integrated. Second, a sensor fusion strategy to obtain the control parameters are defined. Third, the control strategy is presented. Finally, an experimental study to evaluate the sensor architecture and control was developed. One of the advantages of the humanwalker interaction here proposed is the computational efficiency. The sensor processing algorithms and the control strategy are executed in real-time, showing stable performance with human speed changes.

Background In clinical gait assessment, the correct interpretation of gait kinematics and kinetics has a decisive impact on the success of the therapeutic programme. Due to the vast amount of information from which primary anomalies should be identified and separated from secondary compensatory changes, as well as the biomechanical complexity and redundancy of the human locomotion system, this task is considerably challenging and requires the attention of an experienced interdisciplinary team of experts. The ongoing research in the field of biomechanics suggests that mathematical modeling may facilitate this task. This paper explores the possibility of generating a family of toe walking gait patterns by systematically changing selected parameters of a feedback-controlled model. Methods From the selected clinical case of toe walking we identified typical toe walking characteristics and encoded them as a set of gait-oriented control objectives to be achieved in a feedback-controlled walking model. They were defined as fourth order polynomials and imposed via feedback control at the within-step control level. At the between-step control level, stance leg lengthening velocity at the end of the single support phase was adaptively adjusted after each step so as to facilitate gait velocity control. Each time the gait velocity settled at the desired value, selected intra-step gait characteristics were modified by adjusting the polynomials so as to mimic the effect of a typical therapeutical intervention - inhibitory casting. Results By systematically adjusting the set of control parameters we were able to generate a family of gait kinematic and kinetic patterns that exhibit similar principal toe walking characteristics, as they were recorded by means of an instrumented gait analysis system in the selected clinical case of toe walking. We further acknowledge that they to some extent follow similar improvement tendencies as those which one can identify in gait kinematics and kinetics in the selected clinical case after inhibitory casting. Conclusions The proposed walking model that is based on a two-level control strategy has the ability to generate different gait kinematics and kinetics when the set of control parameters that define walking premises change. Such a framework does not have only educational value, but may also prove to have practical implications in pathological gait diagnostics and treatment.