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Kobayashi T.,Orthocare Innovations | Leung A.,Hong Kong Polytechnic University | Akazawa Y.,Hyogo Institute of Assistive Technology | Hutchins S.,University of Salford
Topics in Stroke Rehabilitation | Year: 2012

Background: Ankle-foot orthoses (AFOs) have been reported to have positive effects on the temporal-spatial parameters and kinematics and kinetics of gait in patients with stroke. The center of mass (COM) may be used to represent whole body movement and energy cost in gait, and therefore COM movement would also be positively influenced with use of an appropriate AFO. Objective: To investigate the effect of AFOs on the sagittal plane displacement of the COM in patients with stroke hemiplegia. Methods: Five male subjects with stroke hemiplegia participated in this pilot study. The trajectory of the COM in the sagittal plane, gait speed, bilateral step length, step width, and bilateral stance time were analyzed while participants ambulated under 2 test conditions: with an AFO or with footwear only. The height of the 2 peaks of the vertical displacement of the COM in a gait cycle was subsequently measured and normalized to body height. Statistical analyses were conducted using a nonparametric Friedman test. Results: Gait speed, bilateral step length, and the normalized peak height of the vertical COM trajectory during stance phase on the affected leg all revealed statistically significant increases (P <.05), and step width showed significant decreases (P <.05) under the AFO condition when compared to the footwear-only condition. Conclusions: An AFO may influence the vertical displacement of the COM in patients with stroke hemiplegia. The results of this pilot study therefore suggested that vertical movement of COM could potentially serve as a useful parameter to evaluate the effect of an AFO. © 2012 Thomas Land Publishers, Inc.

Kobayashi T.,Orthocare Innovations | Leung A.K.L.,Hong Kong Polytechnic University | Hutchins S.W.,University of Salford
Journal of Rehabilitation Research and Development | Year: 2011

We performed this review to provide a clearer understanding of how to effectively measure ankle-foot orthosis (AFO) rigidity. This information is important to ensure appropriate orthotic intervention in the treatment of patients with pathological gait. The two main approaches to the investigation of AFO rigidity are (1) bench-testing analyses, in which an AFO is fixed or attached to a measurement device, and (2) functional analyses, in which measurements are taken while a subject is walking with an AFO in situ. This review summarizes and classifies the current state of knowledge of AFO rigidity testing methods. We analyzed the strengths and weaknesses of the methods in order to recommend the most reliable techniques to measure AFO rigidity. The information obtained from this review article would, therefore, benefit both clinicians and engineers involved in the application and design of AFOs.

Howell A.M.,University of Utah | Kobayashi T.,Orthocare Innovations | Hayes H.A.,University of Utah | Foreman K.B.,University of Utah | Bamberg S.J.M.,University of Utah
IEEE Transactions on Biomedical Engineering | Year: 2013

Abnormal gait caused by stroke or other pathological reasons can greatly impact the life of an individual. Being able to measure and analyze that gait is often critical for rehabilitation. Motion analysis labs and many current methods of gait analysis are expensive and inaccessible to most individuals. The low-cost, wearable, and wireless insole-based gait analysis system in this study provides kinetic measurements of gait by using low-cost force sensitive resistors. This paper describes the design and fabrication of the insole and its evaluation in six control subjects and four hemiplegic stroke subjects. Subject-specific linear regression models were used to determine ground reaction force plus moments corresponding to ankle dorsiflexion/plantarflexion, knee flexion/extension, and knee abduction/adduction. Comparison with data simultaneously collected from a clinical motion analysis laboratory demonstrated that the insole results for ground reaction force and ankle moment were highly correlated (all >0.95) for all subjects, while the two knee moments were less strongly correlated (generally >0.80). This provides a means of cost-effective and efficient healthcare delivery of mobile gait analysis that can be used anywhere from large clinics to an individual's home. © 2013 IEEE.

Kobayashi T.,Orthocare Innovations | Orendurff M.S.,Orthocare Innovations | Zhang M.,Hong Kong Polytechnic University | Boone D.A.,Orthocare Innovations
Journal of Biomechanics | Year: 2012

Alignment of lower limb prostheses is important for the gait of amputees. Observed deviations in a particular plane are corrected by altering the prosthetic alignment of the same plane. The assumption is that observed deviations are due to alignment errors within the same plane, but no research has confirmed this assumption. Therefore, the aim of this study was to investigate the out-of-plane effect of systematic alignment changes on socket reaction moments measured by an instrumented prosthesis alignment component in the sagittal and coronal planes in eleven amputees with transtibial prostheses. Each subject walked at self-selected walking speed following randomized controlled angular (±3° and ±6°) and translational (±5. mm and ±10. mm) alignment changes from the nominally aligned condition. The following socket reaction moment parameters were subsequently analyzed: 3 parameters (maximum moment, minimum moment, moment at 45% of stance phase) in the sagittal plane and 2 parameters (moment at 30% and 75% of stance phase) in the coronal plane. A statistical comparison was performed between the nominally aligned and mal-aligned conditions using a repeated measures of ANOVA followed by Scheffe's post-hoc tests. Significant differences were found between the nominally aligned (-0.077±0.078. Nm/kg) and 3° extension (-0.033±0.075. Nm/kg; P=0.0258) and 6° extension (-0.029±0.071. Nm/kg; P=0.0098) conditions in the coronal plane socket reaction moments measured at 30% of stance. Our analysis suggests that the alignment of the transtibial prosthesis should be performed in the sagittal plane first followed by the coronal plane. © 2012 Elsevier Ltd.

Boone D.A.,Orthocare Innovations | Kobayashi T.,Orthocare Innovations | Chou T.G.,Orthocare Innovations | Arabian A.K.,Orthocare Innovations | And 3 more authors.
Gait and Posture | Year: 2013

Alignment - the process and measured orientation of the prosthetic socket relative to the foot - is important for proper function of a transtibial prosthesis. Prosthetic alignment is performed by prosthetists using visual gait observation and amputees' feedback. The aim of this study was to investigate the effect of transtibial prosthesis malalignment on the moments measured at the base of the socket: the socket reaction moments. Eleven subjects with transtibial amputation were recruited from the community. An instrumented prosthesis alignment component was used to measure socket reaction moments during ambulation under 17 alignment conditions, including nominally aligned using conventional clinical methods, and angle perturbations of 3° and 6° (flexion, extension, abduction, and adduction) and translation perturbations of 5. mm and 10. mm (anterior, posterior, lateral, and medial) referenced from the nominal alignment. Coronal alignment perturbations caused systematic changes in the coronal socket reaction moments. All angle and translation perturbations revealed statistically significant differences on coronal socket reaction moments compared to the nominal alignment at 30% and 75% of stance phase (. P<. 0.05). The effect of sagittal alignment perturbations on sagittal socket reaction moments was not as responsive as that of the coronal perturbations. The sagittal angle and translation perturbations of the socket led to statistically significant changes in minimum moment, maximum moment, and moments at 45% of stance phase in the sagittal plane. Therefore, malalignment affected the socket reaction moments in amputees with transtibial prostheses. © 2012 Elsevier B.V..

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