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J. Andrysek - One of the best experts on this subject based on the ideXlab platform.
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Modeling and Design of the Automatic Stance Phase Lock (ASPL) Knee Joint Control Mechanism for Paediatric Users With Transfemoral Amputations
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2020Co-Authors: Calvin C. Ngan, J. AndrysekAbstract:The 2-axes Automatic Stance Phase Lock (ASPL) Stance control mechanism has been demonstrated to improve adult amputees' mobility but has yet to be developed for the paediatric population. The overall objective for this work was to characterize the ASPL control mechanism with biomechanical modelling and design a 2-axes ASPL prosthetic knee joint suitable for children between the ages of 6 and 12 years. Paediatric anthropometric data and ASPL control mechanism performance characteristics established from adult ASPL knee users were utilized to develop paediatric-appropriate configurations of the ASPL Stance control mechanism. Additional predefined design criteria were also included in the detailed knee design. Developed prototypes of the knee joint, Children-ASPL (CASPL) knee, were clinically validated using a single-subject cross-over study design, to assess control mechanism and overall knee functions. Faster walking speed, longer step and stride length with the CASPL knee suggest potential improvements in overall walking performance. The participant also felt confident walking with the CASPL knee and perceived the locking mechanism to be stable. Stemming from the findings here, future design revisions are aimed to improve the performance of the current prototype, including reliability of knee lock disengagement and performance of the swing Phase control mechanism.
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mobility function of a prosthetic knee joint with an automatic Stance Phase lock
Prosthetics and Orthotics International, 2011Co-Authors: J. Andrysek, Susan Klejman, Ricardo Torresmoreno, Winfried Heim, Bryan Steinnagel, Shane GlasfordAbstract:Background: There is a need for a prosthetic knee joint design that is technologically and functionally appropriate for use in developing countries. Objectives: To develop and clinically evaluate a new type of Stance Phase controlled prosthetic knee joint that provides Stance Phase stability without inhibiting swing Phase flexion. Study design: A crossover repeated measures study design comparing the new knee joint to the participant’s conventional low- or high-end prosthetic knee joint. Methods: The new knee joint was fitted to fourteen individuals aged 15 to 67 years with unilateral lower limb amputations. Walk tests were performed to measure walking speed. Energy expenditure was estimated using the physiological cost index (PCI). Results: Walking speeds with the new knee joint were on average 0.14m/s faster than conventional low-end knees (p <0.0001), but 0.07m/s slower than conventional high-end prosthetic knees (p ¼0.008). The PCI was similar across all three knee joint technologies (p ¼0.276). Conclusions: Mobility function with the new knee joint, in terms of walking speed, was more closely matched to high-end than low-end prosthetic knee joints. Therefore, given its relatively simple design, the new Stance Phase control mechanism may offer a functional and cost effective solution for active transfemoral amputees. Clinical relevance This paper describes a new type of prosthetic knee joint mechanism that is intended to be cost-effective while providing high-level Stance Phase function to active individuals with a transfemoral amputation. Initial clinical testing suggests that the new knee joint may have some functional advantages over existing technologies in this category.
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feasibility and design of a low cost prosthetic knee joint using a compliant member for Stance Phase control
Journal of Medical Devices-transactions of The Asme, 2010Co-Authors: Daniel G Harrison, J. Andrysek, W.l. CleghornAbstract:This paper is concerned with the feasibility and design of a low-cost prosthetic knee joint that uses a compliant member for Stance-Phase control. A mechanical locking mechanism was used in conjunction with a compliant control axis to achieve automatic Stance-Phase locking. The concept was developed with the aid of computer-aided engineering software and was validated through the fabrication and testing of a simplified prototype made of an injection moldable polymer. A prosthetic knee joint was then designed, incorporating the compliant member concept. After modeling, fabrication, and laboratory testing, a pilot study was conducted in a clinical setting. A simple gait analysis showed asymmetric gait patterns that demonstrated the need for improved swing-Phase control and damping, while qualitative feedback indicated the desire to reduce the noise produced by the knee. The knee provided the automatic Stance-Phase control for which it was designed and shows significant potential to evolve into a highly functioning, low-cost knee.
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preliminary evaluation of an automatically Stance Phase controlled pediatric prosthetic knee joint using quantitative gait analysis
Archives of Physical Medicine and Rehabilitation, 2007Co-Authors: J. Andrysek, Susan Redekop, S. NaumannAbstract:Abstract Andrysek J, Redekop S, Naumann S. Preliminary evaluation of an automatically Stance-Phase controlled pediatric prosthetic knee joint using quantitative gait analysis. Objectives To evaluate the effects on gait of a new pediatric prosthetic knee joint using an automatic Stance-Phase lock (ASPL), shown previously to help prevent falls, and to propose future design considerations and prosthetic alignments. Design Case series and crossover trial. Setting Human movement laboratory. Participants Three children with unilateral above-knee amputations and 3 children with bilateral above-knee or below-knee amputations. Interventions Not applicable. Main Outcome Measures Spatiotemporal, kinematic, and kinetic gait parameters. Results Spatiotemporal parameters indicated higher gait velocities with the ASPL knee joint for the children with unilateral amputations. The increased speed, as expected, was associated with increased temporal interlimb asymmetry, joint moments and powers, and excessive prosthetic knee range of motion in swing. A trend toward increased pelvic motions was observed with ASPL knee when compared with conventional knees. Conclusions The biomechanic performance of the single-axis ASPL knee joint was shown to be comparable with more complex polycentric pediatric prosthetic knee joint technologies worn by the children in this study.
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Design and quantitative evaluation of a Stance-Phase controlled prosthetic knee joint for children
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2005Co-Authors: J. Andrysek, S. Naumann, W.l. CleghornAbstract:The aims of this study were to demonstrate a theoretical basis for the design of a Stance-Phase controlled paediatric prosthetic knee joint, clinically test prototypes of the knee, and use a questionnaire to evaluate its efficacy. Biomechanical models were used to analyze the Stance-Phase control characteristics of the proposed knee, and those of three other commonly prescribed paediatric knee joint mechanisms, which were also the conventional knee joints used by the six participants of this study (mean age 10.8 years). A questionnaire pertaining to Stance-Phase control was designed and administered twice to each child; once for the evaluation of the prototype knee joint and once for the conventional knee joint. Stance-Phase modeling results indicated decreased zones of instability for the new knee as compared to other paediatric knee joints. Questionnaire results revealed a decrease in the frequency of falls with the prototype compared to other knees, especially in highly active children. The children also reported worrying less about the knee collapsing during walking. No differences were evident for Stance-Phase stability during running, walking on uneven terrain, ambulating up and down stairs and inclines, fatigue, and types of activities performed.
Trevor B Birmingham - One of the best experts on this subject based on the ideXlab platform.
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toe out gait in patients with knee osteoarthritis partially transforms external knee adduction moment into flexion moment during early Stance Phase of gait a tri planar kinetic mechanism
Journal of Biomechanics, 2008Co-Authors: Thomas R Jenkyn, Michael A Hunt, Ian C Jones, Robert J Giffin, Trevor B BirminghamAbstract:Abstract Altered gait kinematics and kinetics are observed in patients with medial compartment knee osteoarthritis. Although various kinematic adaptations are proposed to be compensatory mechanisms that unload the knee, the nature of these mechanisms is presently unclear. We hypothesized that an increased toe-out angle during early Stance Phase of gait shifts load away from the knee medial compartment, quantified as the external adduction moment about the knee. Specifically, we hypothesized that by externally rotating the lower limb anatomy, primarily about the hip joint, toe-out gait alters the lengths of ground reaction force lever arms acting about the knee joint in the frontal and sagittal planes and transforms a portion of knee adduction moment into flexion moment. To test this hypothesis, gait data from 180 subjects diagnosed with medial compartment knee osteoarthritis were examined using two frames of reference. The first frame was attached to the tibia (reporting actual toe-out) and the second frame was attached to the laboratory (simulating no-toe-out). Four measures were compared within subjects in both frames of reference: the lengths of ground reaction force lever arms acting about the knee joint in the frontal and sagittal planes, and the adduction and flexion components of the external knee moment. The mean toe-out angle was 11.4° (S.D. 7.8°, range −2.2° to 28.4°). Toe-out resulted in significant reductions in the frontal plane lever arm (−6.7%) and the adduction moment (−11.7%) in early Stance Phase when compared to the simulated no-toe-out values. These reductions were coincident with significant increases in the sagittal plane lever arm (+33.7%) and flexion moment (+25.0%). Peak adduction lever arm and moment were also reduced significantly in late Stance Phase (by −22.9% and −34.4%, respectively) without a corresponding increase in sagittal plane lever arm or flexion moment. These results indicate that toe-out gait in patients with medial compartment knee osteoarthritis transforms a portion of the adduction moment into flexion moment in early Stance Phase, suggesting that load is partially shifted away from the medial compartment to other structures.
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toe out gait in patients with knee osteoarthritis partially transforms external knee adduction moment into flexion moment during early Stance Phase of gait a tri planar kinetic mechanism
Journal of Biomechanics, 2008Co-Authors: Thomas R Jenkyn, Michael A Hunt, Ian C Jones, Robert J Giffin, Trevor B BirminghamAbstract:Altered gait kinematics and kinetics are observed in patients with medial compartment knee osteoarthritis. Although various kinematic adaptations are proposed to be compensatory mechanisms that unload the knee, the nature of these mechanisms is presently unclear. We hypothesized that an increased toe-out angle during early Stance Phase of gait shifts load away from the knee medial compartment, quantified as the external adduction moment about the knee. Specifically, we hypothesized that by externally rotating the lower limb anatomy, primarily about the hip joint, toe-out gait alters the lengths of ground reaction force lever arms acting about the knee joint in the frontal and sagittal planes and transforms a portion of knee adduction moment into flexion moment. To test this hypothesis, gait data from 180 subjects diagnosed with medial compartment knee osteoarthritis were examined using two frames of reference. The first frame was attached to the tibia (reporting actual toe-out) and the second frame was attached to the laboratory (simulating no-toe-out). Four measures were compared within subjects in both frames of reference: the lengths of ground reaction force lever arms acting about the knee joint in the frontal and sagittal planes, and the adduction and flexion components of the external knee moment. The mean toe-out angle was 11.4 degrees (S.D. 7.8 degrees , range -2.2 degrees to 28.4 degrees ). Toe-out resulted in significant reductions in the frontal plane lever arm (-6.7%) and the adduction moment (-11.7%) in early Stance Phase when compared to the simulated no-toe-out values. These reductions were coincident with significant increases in the sagittal plane lever arm (+33.7%) and flexion moment (+25.0%). Peak adduction lever arm and moment were also reduced significantly in late Stance Phase (by -22.9% and -34.4%, respectively) without a corresponding increase in sagittal plane lever arm or flexion moment. These results indicate that toe-out gait in patients with medial compartment knee osteoarthritis transforms a portion of the adduction moment into flexion moment in early Stance Phase, suggesting that load is partially shifted away from the medial compartment to other structures.
David A Winter - One of the best experts on this subject based on the ideXlab platform.
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motion of the foot and ankle during the Stance Phase in rats
Muscle & Nerve, 2002Co-Authors: Artur S P Varejao, Antonio M Cabrita, Marcel F Meek, Jose Bulascruz, Ronaldo Gabriel, Vitor Filipe, Pedro Melopinto, David A WinterAbstract:Computerized analysis of rat gait is becoming an invaluable technique used by some peripheral nerve investigators for the evaluation of function. In this article we describe the use of a biomechanical model of the foot and ankle that allows a quantitative assessment and description of the ankle angle, reflecting plantarflexion and dorsiflexion during the Stance Phase of gait. Kinematic data of 144 trial walks from 36 normal rats were recorded with a high-speed digital image camera at 225 images per second. The ankle angular changes associated with the specific temporal events of foot placement on the ground through the Stance Phase were assessed. The information obtained was used to propose a new subdivision of the Stance Phase in the rat into three major components. This approach will provide a helpful research tool to analyze gait data that rely on the accurate determination of spatiotemporal foot events.
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biomechanical model of the human foot kinematics and kinetics during the Stance Phase of walking
Journal of Biomechanics, 1993Co-Authors: Stephen Scott, David A WinterAbstract:A model of the human foot is proposed in which the foot is represented as eight rigid segments and eight monocentric, single-degree-of-freedom joints. The soft tissue under the foot is divided into seven independent sites of contact, or loading, and each of these is modelled as a nonlinear spring and a nonlinear damper in-parallel. The model was used to estimate the kinematics and kinetics of the foot during the Stance Phase of walking. The force sustained at each loading site was calculated from walking trials in which only portions of the foot landed on a small force platform. The position of the calcaneus was defined by surface markers, whereas the position of the distal segments were based upon chalk footprints and an estimate of the compression of the plantar soft tissue. The results suggest that the joints that constitute the longitudinal arch extend slightly when the forefoot is loaded. During push-off, these joints flex as the metatarsophalangeal joints extend. Similar kinematic results were estimated when the distal segments of the foot were defined by surface markers. The magnitude of the joint moments of force depended largely on the distribution of the load under the foot which varied considerably between subjects. The stable, yet resilient properties of the foot, as highlighted by this model, should be considered in three-dimensional dynamic models used to study human locomotion. The model provides an objective tool to quantify foot motion and loading, which may prove useful for describing foot function in normal and pathological conditions.
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talocrural and talocalcaneal joint kinematics and kinetics during the Stance Phase of walking
Journal of Biomechanics, 1991Co-Authors: Stephen Scott, David A WinterAbstract:The purpose of this investigation was to study the kinematics and kinetics of the joints between the leg and calcaneus during the Stance Phase of walking. The talocrural and talocalcaneal joints were each assumed to act as monocentric single degree of freedom hinge joints. Motion at one joint was defined by the relative rotation of a point on the opposing joint. The results, based upon the gait of three subjects, showed that the hinge joint assumption may be reasonable. A discrepancy in the kinematics was shown between the talocrural joint rotation and its commonly assumed sagittal plane representation, especially during initial flatfoot. This discrepancy is due to the fact that the sagittal plane rotation is created by the combined rotations of the talocrural and talocalcaneal joints. The talocalcaneal joint showed a peak 25-30 Nm supinatory moment at 80% of Stance. The talocrural joint moment was qualitatively similar to the commonly measured sagittal plane moment, but the present results show that the sagittal plane moment overpredicted the true moment by 6-22% due to the two-dimensional assumption.
Ashkan Vaziri - One of the best experts on this subject based on the ideXlab platform.
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effect of frontal plane tibiofemoral angle on the stress and strain at the knee cartilage during the Stance Phase of gait
Journal of Orthopaedic Research, 2010Co-Authors: Nicholas H Yang, Hamid Nayebhashemi, Paul K Canavan, Ashkan VaziriAbstract:Subject-specific three-dimensional finite element models of the knee joint were created and used to study the effect of the frontal plane tibiofemoral angle on the stress and strain distribution in the knee cartilage during the Stance Phase of the gait cycle. Knee models of three subjects with different tibiofemoral angle and body weight were created based on magnetic resonance imaging of the knee. Loading and boundary conditions were determined from motion analysis and force platform data, in conjunction with the muscle-force reduction method. During the Stance Phase of walking, all subjects exhibited a valgus-varus-valgus knee moment pattern with the maximum compressive load and varus knee moment occurring at approximately 25% of the Stance Phase of the gait cycle. Our results demonstrated that the subject with varus alignment had the largest stresses at the medial compartment of the knee compared to the subjects with normal alignment and valgus alignment, suggesting that this subject might be most susceptible to developing medial compartment osteoarthritis (OA). In addition, the magnitude of stress and strain on the lateral cartilage of the subject with valgus alignment were found to be larger compared to subjects with normal alignment and varus alignment, suggesting that this subject might be most susceptible to developing lateral compartment knee OA.
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effect of frontal plane tibiofemoral angle on the stress and strain at the knee cartilage during the Stance Phase of gait
Journal of Orthopaedic Research, 2010Co-Authors: Nicholas Yang, Hamid Nayebhashemi, Paul K Canavan, Ashkan VaziriAbstract:Subject-specific three-dimensional finite element models of the knee joint were created and used to study the effect of the frontal plane tibiofemoral angle on the stress and strain distribution in the knee cartilage during the Stance Phase of the gait cycle. Knee models of three subjects with different tibiofemoral angle and body weight were created based on magnetic resonance imaging of the knee. Loading and boundary conditions were determined from motion analysis and force platform data, in conjunction with the muscle-force reduction method. During the Stance Phase of walking, all subjects exhibited a valgus–varus–valgus knee moment pattern with the maximum compressive load and varus knee moment occurring at approximately 25% of the Stance Phase of the gait cycle. Our results demonstrated that the subject with varus alignment had the largest stresses at the medial compartment of the knee compared to the subjects with normal alignment and valgus alignment, suggesting that this subject might be most susceptible to developing medial compartment osteoarthritis (OA). In addition, the magnitude of stress and strain on the lateral cartilage of the subject with valgus alignment were found to be larger compared to subjects with normal alignment and varus alignment, suggesting that this subject might be most susceptible to developing lateral compartment knee OA. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1539–1547, 2010
Richard Smith - One of the best experts on this subject based on the ideXlab platform.
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the impact of simulated ankle plantarflexion contracture on the knee joint during Stance Phase of gait a within subject study
Clinical Biomechanics, 2014Co-Authors: Joan Leung, Richard Smith, Lisa A Harvey, Anne M Moseley, Joseph ChapparoAbstract:Abstract Background Ankle plantarflexion contractures are common in adults with neurological disorders and known to cause secondary gait deviations. However, their impact on the knee joint is not fully understood. The aims of this study are to describe the effect of simulated plantarflexion contractures on knee biomechanics during the Stance Phase and on the spatiotemporal characteristics of gait. Methods Mild (10–degree plantarflexion) and severe (20–degree plantarflexion) ankle contractures were simulated in thirteen able-bodied adults using an ankle-foot-orthosis. A no contracture condition was compared with two simulated contracture conditions. Findings There was an increase in knee extension, sometimes resulting in hyperextension, throughout Stance for the two contracture conditions compared to the no contracture condition (mean increase in knee extension ranged from 5° to 9°; 95% CI 0° to 17°). At the same time, there were reductions in extension moment and power generation at the knee. Simulated plantarflexion contractures also reduced gait velocity, bilateral step length and cadence. All these changes were more pronounced in the severe contracture condition than mild contracture condition. While the majority of participants adopted a foot-flat pattern on landing and exhibited an increase in knee extension during Stance, two participants used a toe-walking pattern and exhibited an increase in knee flexion. Interpretation Ankle plantarflexion contractures are associated with an increase in knee extension during Stance Phase. However, some people with simulated ankle contractures may walk with an increase in knee flexion instead. Ankle plantarflexion contractures also adversely affect gait velocity, step length and cadence.
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mechanics and control of the flat versus normal foot during the Stance Phase of walking
Clinical Biomechanics, 2004Co-Authors: Adrienne Hunt, Richard SmithAbstract:Objective. To compare walking Stance Phase rearfoot and forefoot motion, ankle joint moments and extrinsic foot muscle EMG profiles between normal and pes planus feet. Design. A cross-sectional comparative study. Background. Musculoskeletal conditions are often attributed to pes planus, in which motion is assumed to be excessive and the muscle control inadequate. However, many of the speculated differences in mechanics and control between the normal and the pes planus foot have not been quantified. Methods. Kinematic and kinetic data were obtained from video recordings of skin surface markers and a force plate, and EMG was recorded with surface electrodes. Analysis of variance was carried out to compare the group profiles. Results. In the pes planus group: the forefoot was less adducted (P <: 05) at toe-off, and total transverse plane range of motion, at 8� versus 10� , was less (P <: 01); the peak plantarflexor ankle moment at push-off was greater (P <: 05); the invertor moment was greater at foot flat (P <: 05); for the EMG profiles, activity early in Stance, relative to the mean Stance Phase activity was higher (P <: 01) in tibialis anterior and lower (P <: 05) in the peronei, soleus and medial and lateral gastrocnemius. Conclusions. Despite reaching statistical significance, the group differences were small for the task of laboratory walking at a natural pace. The main implications of the differences were for restraint of motion. The expectations of excessive motion and muscle effort in the pes planus group were therefore not substantiated. Relevance
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inter segment foot motion and ground reaction forces over the Stance Phase of walking
Clinical Biomechanics, 2001Co-Authors: Adrienne Hunt, Richard Smith, Marg Torode, Annemaree KeenanAbstract:Abstract Objective . To compare the magnitude and patterns of motion of the rearfoot segment relative to the leg, forefoot segment relative to the rearfoot, height change in the medial longitudinal arch and ground reaction forces of normal adult males during the Stance Phase of walking. Background . Knowledge of normal motion of the rearfoot and forefoot segments and of the arch during Stance Phase is important in clinical management. Methods . Motion data were obtained from surface markers, and force data from a force plate, from the right limb of participants while walking at a self-selected pace. Results . Stance Phase range of motion across sagittal, frontal and transverse planes was 12°, 4° and 10° for the forefoot, compared to 22°, 8° and 10° for the rearfoot. Most motion occurred at the beginning and end of Stance Phase when support was via only the rearfoot or forefoot, and when forces were maximal. Arch height decreased from heel contact and increased after heel rise to its maximum at toe-off. Conclusions . The extent of forefoot segment motion confirms the significance of midfoot joints to normal foot function. Between foot flat and heel rise, the forefoot pattern of motion is indicative of foot stability. Typical foot motion does not obey descriptions of triplanar motion such as `pronation' and `supination'. Relevance Typical Stance Phase foot motion has been described according to a forefoot:rearfoot model and rearfoot:leg model of motion, together with profiles of medial longitudinal arch height and ground reaction forces. This information can be applied in the management of foot dysfunction and should stimulate research into midfoot motion and overall control of the foot.
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extrinsic muscle activity foot motion and ankle joint moments during the Stance Phase of walking
Foot & Ankle International, 2001Co-Authors: Adrienne Hunt, Richard Smith, Marg TorodeAbstract: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.
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three dimensional kinematics of the forefoot rearfoot and leg without the function of tibialis posterior in comparison with normals during Stance Phase of walking
Clinical Biomechanics, 1999Co-Authors: Uangthip Rattanaprasert, Richard Smith, Martin Sullivan, Wendy L GilleardAbstract:Background. Many studies have shown that lack of functional activity of tibialis posterior leads to changes in the longitudinal arch and affects the motion of the foot. A quantitative description of the affects on the motion of the foot in detail has not been reported. Objective. To describe three-dimensional motion of the leg, rearfoot and forefoot with tibialis posterior dysfunction during Stance Phase of walking in comparison with normals. This study compared one case without the function of tibialis posterior with the ensemble average of 10 normals (five males, five females). Methods. Subjects with 10, 12 mm retroreflective markers placed on their right leg, rearfoot and forefoot, performed five trials of walking at self-selected speed on a 10 m walkway. A four-camera three-dimensional motion analysis system and a synchronized force platform were used to record three-dimensional motions of the segments and force variables during Stance Phase of walking. Results. The patterns and range of motion of the rearfoot relative to the leg, and the forefoot relative to the rearfoot demonstrated some differences between the tibialis posterior dysfunction case and normals. Most of the major differences occurred from just prior to heel-off through to toe-off, the period when a stable arch would be required. Conclusion. The observed differences in the three-dimensional foot motions of the tibialis posterior dysfunction case compared with normals during walking were consistent with the expected mechanical consequences of a foot without the function of tibialis posterior. The one exception was the inversion of the rearfoot which remained normal.
