A Biologically Inspired Knee Actuator for a KAFO

2016 ◽  
Vol 10 (4) ◽  
Author(s):  
Feng Tian ◽  
Mohamed Samir Hefzy ◽  
Mohammad Elahinia
Keyword(s):  
Knee Joint ◽  
Knee Flexion ◽  
Gait Cycle ◽  
Knee Extension ◽  
Lateral Side ◽  
Walking Gait ◽  
Normal Knee ◽  
Knee Stiffness ◽  
Control Knee ◽  
Stiffness Profile

Knee–ankle–foot orthoses (KAFOs) are prescribed to improve abnormal ambulation caused by quadriceps weakness. There are three major types of KAFOs: passive KAFOs, semidynamic KAFOs, and dynamic KAFOs. Dynamic KAFOs are the only type that enables to control knee motions throughout the entire walking gait cycle. However, those available in the market are heavy, bulky, and have limited functionality. The UT dynamic KAFO is developed to allow knee flexion and assist knee extension over the gait cycle by using a superelastic nitinol actuator, which has the potential to reduce volume and weight and reproduce normal knee behavior. In order to match the normal knee stiffness profile, the dynamic actuator consists of two actuating parts that work in the stance and swing phases, respectively. Each actuating part combines a superelastic torsional rod and a torsional spring in parallel. Geometries of the two superelastic rods were determined by matlab-based numerical simulations. The simulation response of the dynamic actuator was compared with the normal knee stiffness, verifying that the proposed design is able to mimic the normal knee performance. The surrounding parts of the dynamic knee joint have then been designed and modeled to house the two actuating parts. The dynamic knee joint was fabricated and mounted on a conventional passive KAFO, replacing its original knee joint on the lateral side. Motion analysis tests were conducted on a healthy subject to evaluate the feasibility of the UT dynamic KAFO. The results indicate that the UT dynamic KAFO allows knee flexion during the swing phase of gait and provides knee motion close to normal.

Design and Evaluation of a Knee Actuator for a Dynamic Knee-Ankle-Foot Orthosis

2014 ◽  
Author(s):  
Feng Tian ◽  
Mohammad Elahinia ◽  
Mohamed Samir Hefzy
Keyword(s):  
Knee Joint ◽  
Gait Cycle ◽  
Gait Pattern ◽  
Walking Ability ◽  
Hydraulic Systems ◽  
Walking Gait ◽  
Normal Knee ◽  
Actuation System ◽  
Normal Gait ◽  
In Series

Dynamic KAFOs are developed to recover the normal walking ability during both stance and swing phases. Three types of dynamic KAFOs have been reported in the literature. Various actuation mechanisms including spring, pneumatic and hydraulic systems have been used. These devices can improve walking disability and compensate lower leg muscle deficiency. However, they are bulky, in some cases need complex control systems and do not recreate the normal gait pattern. These shortcomings have limited the application of dynamic KAFOs in daily life. The purpose of this paper is to develop a novel knee actuator for a dynamic KAFO that is actuated easily by employing shape memory materials. Such an actuation system makes the KAFO lightweight and has a greater potential to restore the normal gait. Torsional superelastic alloys are used in this actuator in order to match the stiffness of the knee joint of the KAFO with that of a normal knee joint during the walking gait cycle. There are two distinct parts in the knee actuator, acting independently to mimic the two phases of the gait cycle. One engages only in the stance phase and the other works in the swing phase. Each part is developed by combining a superelastic rod and a stiff rotary spring, in series. According to numerical simulation, such combination reproduces the varying knee stiffness during the whole walking gait. Also mechanical experiments have been conducted to further verify the conceptual design. The simulation and experimental results show that the actuator is able to reproduce the stiffness of the normal knee joint during the gait cycle.

The effect of a knee ankle foot orthosis incorporating an active knee mechanism on gait of a person with poliomyelitis

2013 ◽  
Vol 37 (5) ◽  
pp. 411-414 ◽  
Author(s):  
Mokhtar Arazpour ◽  
Ahmad Chitsazan ◽  
Monireh Ahmadi Bani ◽  
Gholamreza Rouhi ◽  
Farhad Tabatabai Ghomshe ◽  
...  
Keyword(s):  
Knee Flexion ◽  
Walking Speed ◽  
Horizontal Displacement ◽  
Step Length ◽  
Knee Extension ◽  
Knee Joints ◽  
Ankle Foot Orthosis ◽  
Stance Control ◽  
Control Knee ◽  
Foot Orthosis

Background: The aim of this case study was to identify the effect of a powered stance control knee ankle foot orthosis on the kinematics and temporospatial parameters of walking by a person with poliomyelitis when compared to a knee ankle foot orthosis. Case description and methods: A knee ankle foot orthosis was initially manufactured by incorporating drop lock knee joints and custom molded ankle foot orthoses and fitted to a person with poliomyelitis. The orthosis was then adapted by adding electrically activated powered knee joints to provide knee extension torque during stance and also flexion torque in swing phase. Lower limb kinematic and kinetic data plus data for temporospatial parameters were acquired from three test walks using each orthosis. Findings and outcomes: Walking speed, step length, and vertical and horizontal displacement of the pelvis decreased when walking with the powered stance control knee ankle foot orthosis compared to the knee ankle foot orthosis. When using the powered stance control knee ankle foot orthosis, the knee flexion achieved during swing and also the overall pattern of walking more closely matched that of normal human walking. The reduced walking speed may have caused the smaller compensatory motions detected when the powered stance control knee ankle foot orthosis was used. Conclusion: The new powered SCKAFO facilitated controlled knee flexion and extension during ambulation for a volunteer poliomyelitis person. Clinical relevance The powered stance control knee ankle foot orthosis has the potential to improve knee joint kinematics in persons with poliomyelitis when ambulating.

scholarly journals Criterion-Related Validity of Knee Joint-Position-Sense Measurement Using Image Capture and Isokinetic Dynamometry

2015 ◽  
Vol 24 (1) ◽  
Author(s):  
Nicola Relph ◽  
Lee Herrington
Keyword(s):  
Knee Joint ◽  
Knee Flexion ◽  
Cost Effective ◽  
Absolute Error ◽  
Knee Extension ◽  
Position Sense ◽  
Joint Position Sense ◽  
Joint Position ◽  
Image Capture ◽  
Significant Difference

Context: Clinicians require portable, valid, and cost-effective methods to monitor knee joint-position-sense (JPS) ability. Objective: To examine the criterion-related validity of image-capture JPS measures against an isokinetic-dynamometer (IKD) procedure. Design: Random crossover design providing a comparison of knee JPS measures from image capture and IKD procedures. Participants: 10 healthy participants, 5 female, age 28.0 ± 13.29 y, mass 60.3 ± 9.02 kg, height 1.65 ± 0.07 m, and 5 male, 29.6 ± 10.74 y, mass 73.6 ± 5.86 kg, height 1.75 ± 0.07 m. Main Outcome Measures: The dependent variables were absolute error scores (AES) provided by 2 knee directions (flexion and extension). The independent variables were the method (image capture and IKD). Results: There was no significant difference between clinical and IKD AED into knee-extension data (P = .263, r = 0.55). There was a significant difference between clinical and IKD AES into knee-flexion data (P = .016, r =.70). Conclusions: Analysis of photographic images to assess JPS measurements using knee flexion is valid against IKD techniques. However, photo-analysis measurements provided a lower error score using knee-extension data and thus may provide an optimal environment to produce maximal knee JPS acuity. Therefore, clinicians do not need expensive equipment to collect representative JPS ability.

scholarly journals The Effect of Stance Control Orthoses on Gait Characteristics and Energy Expenditure in Knee-Ankle-Foot Orthosis Users

2010 ◽  
Vol 34 (2) ◽  
pp. 206-215 ◽  
Author(s):  
Priya Chantal Davis ◽  
Timothy Michael Bach ◽  
Darren Mark Pereira
Keyword(s):  
Energy Expenditure ◽  
Knee Joint ◽  
Knee Flexion ◽  
Foot Orthoses ◽  
Gait Characteristics ◽  
Stance Control ◽  
Ankle Foot Orthoses ◽  
Locked Knee ◽  
Control Knee ◽  
Walking Velocity

Stance Control knee-ankle foot orthoses (SCO) differ from their traditional locked knee counterparts by allowing free knee flexion during swing while providing stability during stance. It is widely accepted that free knee flexion during swing normalizes gait and therefore improves walking speed and reduces the energy requirements of walking. Limited research has been carried out to evaluate the benefits of SCOs when compared to locked knee-ankle foot orthoses (KAFOs). The purpose of this study was to evaluate the effectiveness of SCOs used for patients with lower limb pathology. Energy expenditure and walking velocity were measured in 10 subjects using an orthosis incorporating a Horton Stance Control knee joint. A GAITRite walkway was used to measure temporospatial gait characteristics. A Cosmed K4b2 portable metabolic system was used to measure energy expenditure and heart rate during walking. Two conditions were tested: Walking with stance control active (stance control) and walking with the knee joint locked. Ten subjects completed the GAITRite testing; nine subjects completed the Cosmed testing. Walking velocity was significantly increased in the stance control condition ( p < 0.001). There was no difference in the energy cost of walking ( p = 0.515) or physiological cost index (PCI) ( p = 0.093) between conditions. This study supports previous evidence that stance control knee-ankle foot orthoses increase walking velocity compared to locked knee devices. Contrary to expectation, the stance control condition did not decrease energy expenditure during walking.

Development of a Dynamic Knee Actuator for a KAFO Using Superelastic Alloys

2014 ◽  
Author(s):  
Feng Tian ◽  
Mohamed Samir Hefzy ◽  
Mohammad Elahinia
Keyword(s):  
Knee Joint ◽  
Gait Cycle ◽  
Swing Phase ◽  
Walking Ability ◽  
Knee Motion ◽  
Walking Gait ◽  
Ankle Foot Orthosis ◽  
Stance Control ◽  
In Series ◽  
Foot Orthosis

A knee-ankle-foot orthosis (KAFO), which covers the knee, ankle and foot, can mitigate abnormal walking pattern caused by weak quadriceps. Several types of KAFOs are currently available in the market: passive KAFOs, stance-control KAFOs and dynamic KAFOs. In passive KAFOs, the knee joint keeps being locked during standing and walking, and can be unlocked manually to allow free rotation for sitting. Stance-control KAFOs (SCKAFOs) allow free knee motion during swing phase when the braced leg is unloaded. Dynamic KAFOs are able to reproduce normal walking ability throughout whole gait cycle. This research is directed at using superelastic alloys to develop a dynamic knee actuator that can be mounted on a traditional passive KAFO. The actuator stiffness can match that of a normal knee joint during the walking gait cycle. This proposed knee actuator utilizes a storing-releasing energy method to apply functional compensation to the knee joint, controlling the knee joint during both stance and swing phases. Fundamentally, the knee actuator is composed of two distinct parts which are connected with the thigh and shank segments, respectively. There are two superelastic actuators that are housed within these two parts and activated independently. Each actuator is developed by combining a superelastic rod and a rotary spring in series. When neither actuator is engaged, the knee joint is allowed to rotate freely. The stance actuator works only in the stance phase and the swing actuator is active for the swing phase. The conceptual design of the knee actuator is verified using numerical simulation and a prototype is developed through additive manufacturing for confirming the concept.

Effect of verbal encouragement on quadriceps and knee joint function during three sets of knee extension exercise

2020 ◽  
pp. 1-7
Author(s):  
Hyunwook Lee ◽  
Jaeyoon Shin ◽  
Daeho Kim ◽  
Jihong Park
Keyword(s):  
Knee Joint ◽  
Knee Flexion ◽  
Knee Extension ◽  
Quadriceps Strength ◽  
Contributing Factors ◽  
Force Output ◽  
Joint Function ◽  
Central Activation ◽  
Verbal Encouragement ◽  
Knee Extension Exercise

BACKGROUND: Although the common practice of verbal encouragement is scientifically supported, its effect on the maintenance of force output in fatiguing exertions is unknown. OBJECTIVE: To examine the effects of verbal encouragement on exercise-induced quadriceps and knee joint function during three sets of knee extension exercise. METHODS: Sixty-five healthy males (23.3 years, 175.8 cm, 75.3 kg) underwent testing using the administration of verbal encouragement (n= 32) or not (n= 33) during assessment of quadriceps and knee joint function. Assessments were performed at baseline and times 1, 2, and 3. The knee concentric isokinetic extension at 60∘/s, was performed between the time points. For quadriceps function, maximal isometric strength and activation (central activation ratio) were recorded. Absolute error values on knee flexion replications at 15∘ or 45∘ were recorded for knee joint function. RESULTS: There was no verbal encouragement effect over three sets of exercise in quadriceps strength (condition × time: F3,189= 1.71, p= 0.17) and knee flexion replication (condition × time for 15∘: F3,189= 0.11, p= 0.96; 45∘: F3,189= 0.63, p= 0.6). However, subjects who had received verbal encouragement maintained quadriceps activation (condition × time: F3,189= 5.49, p= 0.001). Specifically, quadriceps activation in the verbal condition was 3.0% higher at time 2 (p= 0.01) and 4.7% higher at time 3 (p= 0.0003) versus in the non-verbal condition. CONCLUSIONS: Verbal encouragement appears to be effective in maintaining central activation, but is insufficient for promoting strength. This supports the idea that peripheral contributing factors play a larger role in force production when performing multiple sets of exercises.

Quantitative and temporal differential recovery of articular and muscular limitations of knee joint contractures; results in a rat model

2014 ◽  
Vol 117 (7) ◽  
pp. 730-737 ◽  
Author(s):  
Guy Trudel ◽  
Odette Laneuville ◽  
Elizabeth Coletta ◽  
Louis Goudreau ◽  
Hans K. Uhthoff
Keyword(s):  
Knee Joint ◽  
Knee Flexion ◽  
Quantitative Data ◽  
Spontaneous Recovery ◽  
Knee Extension ◽  
Joint Contractures ◽  
Recent Onset ◽  
Flexion Contractures ◽  
Before And After ◽  
Differential Contribution

Joint contractures alter the mechanical properties of articular and muscular structures. Reversibility of a contracture depends on the restoration of the elasticity of both structures. We determined the differential contribution of articular and muscular structures to knee flexion contractures during spontaneous recovery. Rats (250, divided into 24 groups) had one knee joint surgically fixed in flexion for six different durations, from 1 to 32 wk, creating joint contractures of various severities. After the fixation was removed, the animals were left to spontaneously recover for 1 to 48 wk. After the recovery periods, animals were killed and the knee extension was measured before and after division of the transarticular posterior muscles using a motorized arthrometer. No articular limitation had developed in contracture of recent onset (≤2 wk of fixation, P > 0.05); muscular limitations were responsible for the majority of the contracture (34 ± 8° and 38 ± 6°, respectively; both P < 0.05). Recovery for 1 and 8 wk reversed the muscular limitation of contractures of recent onset (1 and 2 wk of fixation, respectively). Long-lasting contractures (≥4 wk of fixation) presented articular limitations, irreversible in all 12 durations of recovery compared with controls (all 12 P < 0.05). Knee flexion contractures of recent onset were primarily due to muscular structures, and they were reversible during spontaneous recovery. Long-lasting contractures were primarily due to articular structures and were irreversible. Comprehensive temporal and quantitative data on the differential reversibility of mechanically significant alterations in articular and muscular structures represent novel evidence on which to base clinical practice.

Examination of Knee Joint Moments on the Function of Knee-Ankle-Foot Orthoses During Walking

2013 ◽  
Vol 29 (4) ◽  
pp. 474-480 ◽  
Author(s):  
Jan Andrysek ◽  
Susan Klejman ◽  
John Kooy
Keyword(s):  
Knee Joint ◽  
Stance Phase ◽  
Knee Extension ◽  
Knee Joints ◽  
Foot Orthoses ◽  
Variable Effect ◽  
Stance Control ◽  
Ankle Foot Orthoses ◽  
Control Knee ◽  
Load Transducer

The goal of this study was to investigate clinically relevant biomechanical conditions relating to the setup and alignment of knee-ankle-foot orthoses and the influence of these conditions on knee extension moments and orthotic stance control during gait. Knee moments were collected using an instrumented gait laboratory and concurrently a load transducer embedded at the knee-ankle-foot orthosis knee joint of four individuals with poliomyelitis. We found that knee extension moments were not typically produced in late stance-phase of gait. Adding a dorsiflexion stop at the orthotic ankle significantly decreased the knee flexion moments in late stance-phase, while slightly flexing the knee in stance-phase had a variable effect. The findings suggest that where users of orthoses have problems initiating swing-phase flexion with stance control orthoses, an ankle dorsiflexion stop may be used to enhance function. Furthermore, the use of stance control knee joints that lock while under flexion may contribute to more inconsistent unlocking of the stance control orthosis during gait.

scholarly journals Jogging and Practical-Duration Foam-Rolling Exercises and Range of Motion, Proprioception, and Vertical Jump in Athletes

2019 ◽  
Vol 54 (11) ◽  
pp. 1171-1178 ◽  
Author(s):  
Natalia Romero-Franco ◽  
Javier Romero-Franco ◽  
Pedro Jiménez-Reyes
Keyword(s):  
Knee Joint ◽  
Range Of Motion ◽  
Knee Flexion ◽  
Vertical Jump ◽  
Knee Extension ◽  
Position Sense ◽  
Joint Position Sense ◽  
Joint Position ◽  
Foam Rolling ◽  
Hip Extension

Context Foam-rolling exercises are frequently included in warmups due to their benefits for increasing range of motion (ROM). However, their effects on proprioception and vertical jump have not been analyzed and therefore remain unclear. Moreover, the effects of performing practical-duration foam-rolling exercises after typical warmup exercises such as jogging are unknown. Objective To analyze the effects of jogging and practical-duration foam-rolling exercises on the ROM, knee proprioception, and vertical jump of athletes. Design Randomized controlled study. Setting Sports laboratory and university track. Patients or Other Participants Thirty athletes were randomly classified into an experimental group (EG) or control group (CG). Intervention(s) The EG performed 8-minute jogging and foam-rolling exercises. The CG performed 8-minute jogging. Main Outcome Measure(s) Knee flexion, hip extension, active knee extension, ankle dorsiflexion (ADF), knee-joint position sense, and countermovement jump (CMJ) were evaluated before the intervention (baseline), after (post 0 min), and 10 minutes later. Results The EG exhibited higher values for ADF and CMJ at post 0 min (ADF: P &lt; .001, d = 0.88; CMJ: P &lt; .001, d = 0.52) and 10 minutes later (ADF: P = .014, d = 0.41; CMJ: P = .006, d = 0.22) compared with baseline. Although the CG also showed increased CMJ at post 0 min (P = .044, d = 0.21), the EG demonstrated a greater increase (P = .021, d = 0.97). No differences were found in the remaining ROM variables (knee flexion, hip extension, active knee extension: P values &gt; .05). For knee-joint position sense, no differences were found (P &gt; .05). Conclusions Combining jogging and practical-duration foam rolling may increase ADF and CMJ without affecting knee proprioception and hip or knee ROM. Jogging by itself may slightly increase ADF and CMJ, but the results were better and were maintained after 10 minutes when foam rolling was added.

scholarly journals Real-Time Identification of Knee Joint Walking Gait as Preliminary Signal for Developing Lower Limb Exoskeleton

Electronics ◽  
2021 ◽  
Vol 10 (17) ◽  
pp. 2117
Author(s):  
Susanto Susanto ◽  
Ipensius Tua Simorangkir ◽  
Riska Analia ◽  
Daniel Sutopo Pamungkas ◽  
Hendawan Soebhakti ◽  
...  
Keyword(s):  
Knee Joint ◽  
Real Time ◽  
Gait Cycle ◽  
Initial Step ◽  
Knee Joints ◽  
Walking Gait ◽  
Lower Limb Exoskeleton ◽  
Walking Rehabilitation ◽  
Research Experiment ◽  
Real Time Identification

An exoskeleton is a device used for walking rehabilitation. In order to develop a proper rehabilitation exoskeleton, a user’s walking intention needs to be captured as the initial step of work. Moreover, every human has a unique walking gait style. This work introduced a wearable sensor, which aimed to recognize the walking gait phase, as the fundamental step before applying it into the rehabilitation exoskeleton. The sensor used in this work was the IMU sensor, used to recognize the pitch angle generated from the knee joint while the user walks, as information about the walking gait cycle, before doing the investigation on how to identify the walking gait cycle. In order to identify the walking gait cycle, Neural Network has been proposed as a method. The gait cycle identification was generated to recognize the gait cycle on the knee joint. To verify the performance of the proposed method, experiments have been done in real-time application. The experiments were carried out with different processes such as walking on a flat floor, climbing up, and walking down stairs. Five subjects were trained and tested using the system. The experiments showed that the proposed method was able to recognize each gait cycle for all users as they wore the sensor on their knee joints. This study has the potential to be applied on an exoskeleton rehabilitation robot as a further research experiment.

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