Seattle, WA, United States
Seattle, WA, United States

Time filter

Source Type

Singer M.L.,University of Utah | Kobayashi T.,Orthocare Innovations | Lincoln L.S.,Orthocare Innovations | Orendurff M.S.,Orthocare Innovations | Foreman K.B.,University of Utah
Clinical Biomechanics | Year: 2014

Background Stiffness of an ankle-foot orthosis plays an important role in improving gait in patients with a history of stroke. To address this, the aim of this case series study was to determine the effect of increasing plantarflexion stiffness of an ankle-foot orthosis on the sagittal ankle and knee joint angle and moment during the first and second rockers of gait.Methods Gait data were collected in 5 subjects with stroke at a self-selected walking speed under two plantarflexion stiffness conditions (0.4 Nm/°and 1.3 Nm/°) using a stiffness-adjustable experimental ankle-foot orthosis on a Bertec split-belt fully instrumented treadmill in a 3-dimensional motion analysis laboratory.Findings By increasing the plantarflexion stiffness of the ankle-foot orthosis, peak plantarflexion angle of the ankle was reduced and peak dorsiflexion moment was generally increased in the first rocker as hypothesized. Two subjects demonstrated increases in both peak knee flexion angle and peak knee extension moment in the second rocker as hypothesized. The two subjects exhibited minimum contractility during active plantarflexion, while the other three subjects could actively plantarflex their ankle joint.Interpretation It was suggested that those with the decreased ability to actively plantarflex their ankle could not overcome excessive plantarflexion stiffness at initial contact of gait, and as a result exhibited compensation strategies at the knee joint. Providing excessively stiff ankle-foot orthoses might put added stress on the extensor muscles of the knee joint, potentially creating fatigue and future pathologies in some patients with stroke. © 2014 Elsevier Ltd.


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 | 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.


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.


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.


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..


Kobayashi T.,Orthocare Innovations | Arabian A.K.,Seattle Pacific University | Orendurff M.S.,Orthocare Innovations | Rosenbaum-Chou T.G.,Orthocare Innovations | Boone D.A.,Orthocare Innovations
Clinical Biomechanics | Year: 2014

Background Energy storage and return feet are designed for active amputees. However, little is known about the socket reaction moments in transtibial prostheses with energy storage and return feet. The aim of this study was to investigate the effect of alignment changes on the socket reaction moments during gait while using the energy storage and return feet. Methods A Smart Pyramid™ was used to measure the socket reaction moments in 10 subjects with transtibial prostheses while walking under 25 alignment conditions, including a nominal alignment (as defined by conventional clinical methods), as well as angle malalignments of 2, 4 and 6 (flexion, extension, abduction, and adduction) and translation malalignments of 5 mm, 10 mm and 15 mm (anterior, posterior, lateral, and medial) referenced from the nominal alignment. The socket reaction moments of the nominal alignment were compared with each malalignment. Findings Both coronal and sagittal alignment changes demonstrated systematic effects on the socket reaction moments. In the sagittal plane, angle and translation alignment changes demonstrated significant differences (P < 0.05) in the minimum moment, the moment at 45% of stance and the maximum moment for some comparisons. In the coronal plane, angle and translation alignment changes demonstrated significant differences (P < 0.05) in the moment at 30% and 75% of stance for all comparisons. Interpretation The alignment may have systematic effects on the socket reaction moments in transtibial prostheses with energy storage and return feet. The socket reaction moments could potentially be a useful biomechanical parameter to evaluate the alignment of the transtibial prostheses. © 2013 Elsevier Ltd.


Kobayashi T.,Orthocare Innovations | Orendurff M.S.,Orthocare Innovations | Arabian A.K.,Seattle Pacific University | Rosenbaum-Chou T.G.,Orthocare Innovations | Boone D.A.,Orthocare Innovations
Journal of Biomechanics | Year: 2014

The alignment of a lower limb prosthesis affects the way load is transferred to the residual limb through the socket, and this load is critically important for the comfort and function of the prosthesis. Both magnitude and duration of the moment are important factors that may affect the residual limb health. Moment impulse is a well-accepted measurement that incorporates both factors via moment-time integrals. The aim of this study was to investigate the effect of alignment changes on the socket reaction moment impulse in transtibial prostheses. Ten amputees with transtibial prostheses participated in this study. The socket reaction moment impulse was measured at a self-selected walking speed using a Smart PyramidTM in 25 alignment conditions, including a nominal alignment (clinically aligned by a prosthetist), as well as angle malalignments of 2°, 4° and 6° (abduction, adduction, extension and flexion) and translation malalignments of 5. mm, 10. mm and 15. mm (lateral, medial, anterior and posterior). The socket reaction moment impulse of the nominal alignment was compared for each condition. The relationship between the alignment and the socket reaction moment impulse was clearly observed in the coronal angle, coronal translation and sagittal translation alignment changes. However, this relationship was not evident in the sagittal angle alignment changes. The results of this study suggested that the socket reaction moment impulse could potentially serve as a valuable parameter to assist the alignment tuning process for transtibial prostheses. Further study is needed to investigate the influence of the socket reaction moment impulse on the residual limb health. © 2014 Elsevier Ltd.


Kobayashi T.,Orthocare Innovations | Orendurff M.S.,Orthocare Innovations | Boone D.A.,Orthocare Innovations
Journal of Biomechanics | Year: 2013

The alignment of a lower-limb prosthesis is critical to the successful prosthetic fitting and utilization by the wearer. Loads generated by the socket applied to the residual limb while walking are thought to be different in transfemoral and knee-disarticulation prostheses. The aim of this case series was to compare the socket reaction moments between transfemoral and knee-disarticulation prostheses and to investigate the effect of alignment changes on them. Two amputees, one with a transfemoral prosthesis and another with a knee-disarticulation prosthesis, participated in this study. A Smart Pyramid™ was used to measure socket reaction moments while walking under 9 selected alignment conditions; including nominally aligned, angle malalignments of 6° (flexion, extension, abduction and adduction) and translation malalignments of 15. mm (anterior, posterior, medial and lateral) of the socket relative to the foot. This study found that the pattern of the socket reaction moments was similar between transfemoral and knee-disarticulation prostheses. An extension moment in the sagittal plane and a varus moment in the coronal plane were dominant during stance under the nominally aligned condition. This study also demonstrated that alignment changes might have consistent effects on the socket reaction moments in transfemoral and knee-disarticulation prostheses. Extension and posterior translation of the socket resulted in increases in an extension moment, while abduction and lateral translation of the socket resulted in increases in a varus moment. The socket reaction moments may potentially serve as useful biomechanical parameters to evaluate alignment in transfemoral and knee-disarticulation prostheses. © 2013 Elsevier Ltd.


Kobayashi T.,Orthocare Innovations | Orendurff M.S.,Orthocare Innovations | Zhang M.,Hong Kong Polytechnic University | Boone D.A.,Orthocare Innovations
Journal of Biomechanics | Year: 2013

Alignment is important for comfortable and stable gait of lower-limb prosthesis users. The magnitude of socket reaction moments in the multiple planes acting simultaneously upon the residual limb may be related to perception of comfort in individuals using prostheses through socket interface pressures. The aim of this study was to investigate the effect of prosthetic alignment changes on sagittal and coronal socket reaction moment interactions (moment-moment curves) and to characterize the curves in 11 individuals with transtibial amputation using novel moment-moment interaction parameters measured by plotting sagittal socket reaction moments versus coronal ones under various alignment conditions. A custom instrumented prosthesis alignment component was used to measure socket reaction moments during walking. Prosthetic alignment was tuned to a nominally aligned condition by a prosthetist, and from this position, angular (3° and 6° of flexion, extension, abduction or adduction of the socket) and translational (5. mm and 10. mm of anterior, posterior, medial or lateral translation of the socket) alignment changes were performed in either the sagittal or the coronal plane in a randomized manner. A total of 17 alignment conditions were tested. Coronal angulation and translation alignment changes demonstrated similar consistent changes in the moment-moment curves. Sagittal alignment changes demonstrated more complex changes compared to the coronal alignment changes. Effect of sagittal angulations and translations on the moment-moment curves was different during 2nd rocker (mid-stance) with extension malalignment appearing to cause medio-lateral instability. Presentation of coronal and sagittal socket reaction moment interactions may provide useful visual information for prosthetists to understand the biomechanical effects of malalignment of transtibial prostheses. © 2013 Elsevier Ltd.

Loading Orthocare Innovations collaborators
Loading Orthocare Innovations collaborators