Effects of Knee-Ankle-Foot Orthosis with Knee Joint Capable of Knee Flexion Control on the Gait of Stroke Patients

Background:Traditionally, the anatomical knee joint is locked in extension when walking with a conventional knee–ankle–foot orthosis. A powered knee–ankle–foot orthosis was developed to provide restriction of knee flexion during stance phase and active flexion and extension of the knee during swing phase of gait.Objective:The purpose of this study was to determine differences of the powered knee–ankle–foot orthosis compared to a locked knee–ankle–foot orthosis in kinematic data and temporospatial parameters during ambulation.Study design:Quasi—experimental design.Methods:Subjects with poliomyelitis (n = 7) volunteered for this study and undertook gait analysis with both the powered and the conventional knee–ankle–foot orthoses. Three trials per orthosis were collected while each subject walked along a 6-m walkway using a calibrated six-camera three-dimensional video-based motion analysis system.Results:Walking with the powered knee–ankle–foot orthosis resulted in a significant reduction in both walking speed and step length (both 18%), but a significant increase in stance phase percentage compared to walking with the conventional knee–ankle–foot orthosis. Cadence was not significantly different between the two test conditions ( p = 0.751). There was significantly higher knee flexion during swing phase and increased hip hiking when using the powered orthosis.Conclusion:The new powered orthosis permitted improved knee joint kinematic for knee–ankle–foot orthosis users while providing knee support in stance and active knee motion in swing in the gait cycle. Therefore, the new powered orthosis provided more natural knee flexion during swing for orthosis users compared to the locked knee–ankle–foot orthosis.Clinical relevanceThis orthosis has the potential to improve knee joint kinematics and gait pattern in poliomyelitis subjects during walking activities.

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Loads on the uprights of a knee-ankle-foot orthosis

Prosthetics and Orthotics International ◽

10.1177/0309364610393062 ◽

2011 ◽

Vol 35 (1) ◽

pp. 106-112 ◽

Cited By ~ 4

Author(s):

KA Bernhardt ◽

KR Kaufman

Keyword(s):

Knee Joint ◽

Knee Flexion ◽

Sagittal Plane ◽

Case Series ◽

Case Description ◽

Ankle Foot Orthosis ◽

Component Design ◽

Load Sensor ◽

Design Case ◽

Foot Orthosis

Background: Objective design criteria for orthotic components is lacking. This paucity of data results in prescription guidelines based on assumptions or practitioners' past experience, and the potential for incorrectly designed components. The purpose of this study was to directly measure loads on the knee joint of a knee-ankle-foot orthosis.Study design: Case series.Case Description and Methods: Three subjects who had been prescribed a knee-ankle-foot orthosis for quadriceps weakness underwent gait analysis and orthotic upright load data collection. A load sensor to measure the three force and three moment components was used in place of the lateral knee joint while the subjects walked in three knee flexion positions.Findings and Outcomes: Forces were highest in compression and moments were greatest in the sagittal plane. The kinetics did not increase solely with patient weight. There was substantial variability between subjects.Conclusions: This data will help guide orthotic component design and prescription guidelines. Knowledge of loading conditions will lead to more optimal orthotic intervention for patients and increased patient satisfaction.Clinical relevanceThis study is one of the first to directly measure loads on the upright of a KAFO. These data provide objective targets for engineering design. The data from this small case series can also be used to establish guidelines for patient device selection.

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Defining the Mechanical Properties of a Spring-hinged Ankle Foot Orthosis to Assess its Potential Use in Children With Spastic Cerebral Palsy

Journal of Applied Biomechanics ◽

10.1123/jab.2014-0046 ◽

2014 ◽

Vol 30 (6) ◽

pp. 728-731 ◽

Cited By ~ 9

Author(s):

Yvette L. Kerkum ◽

Merel-Anne Brehm ◽

Annemieke I. Buizer ◽

Josien C. van den Noort ◽

Jules G. Becher ◽

...

Keyword(s):

Mechanical Properties ◽

Cerebral Palsy ◽

Knee Flexion ◽

Spastic Cerebral Palsy ◽

Gait Performance ◽

Ankle Foot Orthosis ◽

The Moment ◽

Potential Use ◽

Foot Orthosis ◽

Walking Energy Cost

A rigid ventral shelf ankle foot orthosis (AFO) may improve gait in children with spastic cerebral palsy (SCP) whose gait is characterized by excessive knee flexion in stance. However, these AFOs can also impede ankle range of motion (ROM) and thereby inhibit push-off power. A more spring-like AFO can enhance push-off and may potentially reduce walking energy cost. The recent development of an adjustable spring-hinged AFO now allows adjustment of AFO stiffness, enabling tuning toward optimal gait performance. This study aims to quantify the mechanical properties of this spring-hinged AFO for each of its springs and settings. Using an AFO stiffness tester, two AFO hinges and their accompanying springs were measured. The springs showed a stiffness range of 0.01−1.82 N·m·deg−1. The moment-threshold increased with increasing stiffness (1.13–12.1 N·m), while ROM decreased (4.91–16.5°). Energy was returned by all springs (11.5–116.3 J). These results suggest that the two stiffest available springs should improve joint kinematics and enhance push-off in children with SCP walking with excessive knee flexion.

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