Passive Orthosis Research Articles

A biomechanics and energetics dataset of neurotypical adults walking with and without kinematic constraints

Numerous studies have explored the biomechanics and energetics of human walking, offering valuable insights into how we walk. However, prior studies focused on changing external factors (e.g., walking speed) and examined group averages and trends rather than individual adaptations in the presence of internal constraints (e.g., injury-related muscle weakness). To address this gap, this paper presents an open dataset of human walking biomechanics and energetics collected from 21 neurotypical young adults. To investigate the effects of internal constraints (reduced joint range of motion), the participants are both the control group (free walking) and the intervention group (constrained walking - left knee fully extended using a passive orthosis). Each subject walked on a dual-belt treadmill at three speeds (0.4, 0.8, and 1.1 m/s) and five step frequencies ( − 10% to 20% of their preferred frequency) for a total of 30 test conditions. The dataset includes raw and segmented data featuring ground reaction forces, joint motion, muscle activity, and metabolic data. Additionally, a sample code is provided for basic data manipulation and visualisation.

Optimal Design of Lower Limb Rehabilitation System Based on Parallel and Serial Mechanisms

This paper presents the structure and model of a hybrid modular structure of a robotic system for lower limb rehabilitation. It is made of two modules identical in structure, including an active 3-PRRR manipulator for moving the patient’s foot and a passive orthosis based on the RRR mechanism for supporting the lower limb. A mathematical model has been developed to describe the positions for the links of the active and passive mechanisms of two modules, as a function of the angles in the joints of the passive orthosis, considering constraints for attaching the active manipulators to the moving platform and their configurations. A method has been formulated for a parametric synthesis of the hybrid robotic system proposed with modular structure, taking into account the generated levels of parametric constraints depending on the ergonomic and manufacturability features. The proposed design is based on a criterion in the form of a convolution, including two components, one of which is based on minimizing unattainable points of the trajectory, considering the characteristics of anthropometric data, and the other is based on the compactness of the design. The results of the mathematical modeling are discussed as well as the analysis results towards a prototype validation.

Direct biomechanical manipulation of human gait stability: A systematic review.

People fall more often when their gait stability is reduced. Gait stability can be directly manipulated by exerting forces or moments onto a person, ranging from simple walking sticks to complex wearable robotics. A systematic review of the literature was performed to determine: What is the level of evidence for different types of mechanical manipulations on improving gait stability? The study was registered at PROSPERO (CRD42020180631). Databases Embase, Medline All, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, and Google Scholar were searched. The final search was conducted on the 1st of December, 2022. The included studies contained mechanical devices that influence gait stability for both impaired and non-impaired subjects. Studies performed with prosthetic devices, passive orthoses, and analysing post-training effects were excluded. An adapted NIH quality assessment tool was used to assess the study quality and risk of bias. Studies were grouped based on the type of device, point of application, and direction of forces and moments. For each device type, a best-evidence synthesis was performed to quantify the level of evidence based on the type of validity of the reported outcome measures and the study quality assessment score. Impaired and non-impaired study participants were considered separately. From a total of 4701 papers, 53 were included in our analysis. For impaired subjects, indicative evidence was found for medio-lateral pelvis stabilisation for improving gait stability, while limited evidence was found for hip joint assistance and canes. For non-impaired subjects, moderate evidence was found for medio-lateral pelvis stabilisation and limited evidence for body weight support. For all other device types, either indicative or insufficient evidence was found for improving gait stability. Our findings also highlight the lack of consensus on outcome measures amongst studies of devices focused on manipulating gait.

Numerical analysis of a novel silicone sole-based passive orthosis for home gait rehabilitation training

Drop foot syndrome is a neuromuscular disease characterized by weakness of the muscles in the front of the lower leg. This disease can cause partial or complete loss of control over the foot and affects the ability to lift the foot from the ankle. Orthoses are used to help improve the gait of patients with limited control over the foot muscles. The most important advantages of passive orthoses are that they are light and inexpensive. Thermoplastic materials are generally preferred in lower extremity orthoses due to their high strength and elasticity. The novelty of this study was to examine the mechanical behavior of the proposed passive orthosis at different weight forces. It was observed that displacement, stress and strain values increased with the increase of weight force and vibration frequency. Consequently, Polypropylene-based orthosis was accepted as the ideal design material as it exhibits higher elastic behavior than Polyetherimide and Polylactic Acid-based orthoses. Consequently, this study enables researchers a useful reference on passive orthosis parameters such as modeling, material behavior, shape control, geometry, and size optimization for key biomechanical engineering applications.

Study of a Passive Orthosis for Reducing the Load Transfer in the Hip Joint

There are several orthoses that allow for the assistance of movement on the lower limbs, mainly flexion–extension. However, there is still a lack of systems that allow, in addition to assisting movement, for transferring the load from weakened anatomical parts to physically healthy joints. A model of a passive and light orthosis that is capable of transferring part of the load from the hip joint directly to the body of the femur was developed and tested. This helps to attenuate the longitudinal component of the force, thus reducing pain and the patient’s discomfort. Computer-aided design (CAD) models and numerical studies were conducted using an offline model of the hip forces, and a proof-of-concept prototype was also developed for experimental validation. The model uses a rigid ergonomic structure and an elastic energy-accumulating device, in this case, a spring, whose preload can be regulated for controlling the assistance’s level. The numeric simulations demonstrated the adequacy of the model for a spring pre-load of 20% of the force applied to the femoral head, reducing the load in the hip joint. The hypothesis of the present study, that the orthosis can reduce the reaction load on the hip joint, was validated by the computational model developed and by the preliminary experimental results obtained with the concept prototype. The approached model represents a promising starting point for subsequent studies and progression for the practical and clinical field.

Effect of Reciprocating Gait Orthosis with Hip Actuation on Upper Extremity Loading during Ambulation in Patient with Spinal Cord Injury: A Single Case Study

Reciprocating gait orthosis (RGO) is a traditional passive orthosis that provides postural stability and allows for independent upright ambulation with the assistance of walking aids, such as crutches, canes, and walkers. Previous follow-up studies of patients with RGOs have indicated a high frequency of nonusage. One of the main reasons for avoiding the use of RGOs is the excessive upper extremity loading induced by walking aids. The purpose of this study was to investigate the effect of hip actuation on the upper extremity loading induced by crutches when ambulating with an RGO. One female individual with a chronic complete spinal cord injury classified as ASIA A participated in this study. We compared the upper extremity loading during ambulation when individualized hip assistive forces were applied on the RGO (POWERED condition) and when wearing the RGO without actuation (RGO condition). Upper extremity loading was assessed by measuring the forces acting on the crutches. Compared with the RGO condition, the average upper extremity loading per unit distance and per unit time were lower for the POWERED condition by 15.21% (RGO: 0.307 ± 0.056 and POWERED: 0.260 ± 0.034 %bw·m−1) and by 21.19% (RGO: 0.120 ± 0.020 and POWERED: 0.094 ± 0.011 %bw·s−1), respectively. We believe that a substantial reduction in upper extremity loading during ambulation provided by hip actuation holds promise to promote long-term RGO use and enable patients with paraplegia to perform frequent and intensive rehabilitation training. As this is a single case study, subsequent studies should aim to verify this effect through a higher number of patients and to different injury levels.

EEG Spectral Feature Modulations Associated With Fatigue in Robot-Mediated Upper Limb Gross and Fine Motor Interactions.

This paper investigates the EEG spectral feature modulations associated with fatigue induced by robot-mediated upper limb gross and fine motor interactions. Twenty healthy participants were randomly assigned to perform a gross motor interaction with HapticMASTER or a fine motor interaction with SCRIPT passive orthosis for 20 min or until volitional fatigue. Relative and ratio band power measures were estimated from the EEG data recorded before and after the robot-mediated interactions. Paired-samples t-tests found a significant increase in the relative alpha band power and a significant decrease in the relative delta band power due to the fatigue induced by the robot-mediated gross and fine motor interactions. The gross motor task also significantly increased the (θ + α)/β and α/β ratio band power measures, whereas the fine motor task increased the relative theta band power. Furthermore, the robot-mediated gross movements mostly changed the EEG activity around the central and parietal brain regions, whereas the fine movements mostly changed the EEG activity around the frontopolar and central brain regions. The subjective ratings suggest that the gross motor task may have induced physical fatigue, whereas the fine motor task may have induced mental fatigue. Therefore, findings affirm that changes to localised brain activity patterns indicate fatigue developed from the robot-mediated interactions. It can also be concluded that the regional differences in the prominent EEG spectral features are most likely due to the differences in the nature of the task (fine/gross motor and distal/proximal upper limb) that may have differently altered an individual's physical and mental fatigue level. The findings could potentially be used in future to detect and moderate fatigue during robot-mediated post-stroke therapies.

Design and motion control scheme of a new stationary trainer to perform lower limb rehabilitation therapies on hip and knee joints

Limb disability is one of the serious problems and rehabilitation of lower limb requires an assistive force to the patient. A new design for stationary trainer for performing rehabilitation therapies for lower limb at the knee as well as hip joints in the sitting/lying positions is presented in this article. A passive orthosis (similar to an exoskeleton) is suggested in this system to provide a support to lower limb of the patient. The suggested mechanism also comprises of an active Cartesian manipulator based upon a spatial three parallel prismatic–revolute–revolute–revolute kinematic arrangement to perform the required limb therapeutic motions in the transverse/horizontal/lateral and sagittal/longitudinal plane. Numerically, the usefulness of the designed stationary trainer is confirmed using computer-based simulations along with a motion control scheme by performing various clinically suggested therapeutic motion tracking (passive range of motions) tasks. The article demonstrates the accomplishment of the control scheme for various training procedures of the lower limb.

Development of pneumatic artificial muscle type active ankle foot orthosis capable of assisting depending on the walking phase

Many ankle foot orthoses have been developed to assist the hemiplegic person in walking, but most of them are passive orthoses that can perform the necessary auxiliary functions only in a specific phase during walking. Therefore, we have developed an active ankle foot orthosis that divides the walking cycle into four phases by measuring the ground contact of the heel and the ball of the finger with a pressure sensor, and can set ankle plantar dorsiflexion motion assist depending on the phase.

Development and Preliminary Evaluation of a Lower Body Exosuit to Support Ankle Dorsiflexion

For patients suffering from drop foot due to weakness of ankle dorsiflexion muscles, an ankle foot orthosis provides increased foot clearance during the swing phase of gait, but often restricts other gait functions, such as plantarflexion. Due to steady progress in the development of lighter and smaller actuator technologies, active wearable devices such as exosuits become relevant for rehabilitation, since they can offer an extended functionality including a more comfortable wear than passive plastic orthosis. The aim of the paper is to present a lightweight exosuit supporting dorsiflexion during gait with autonomous recognition of gait phases and conditions. One main requirement during the iterative development of the exosuit is a non-restrictive function, thus no differences between the assisted and non-assisted gait of a healthy subject should occur. We therefore conducted a pilot biomechanics study using statistical parametric mapping to analyze kinematics of the ankle joint and muscle activity of m. tibialis anterior of nine subjects without any gait anomalies walking with and without the exosuit. The results show no significant difference between with and without support. In contrast to passive orthosis, the developed system could be an enhanced solution to assist patients suffering from drop foot, which should be analyzed in the next step for evaluating the development.

Design of mechanisms of a robotic system for rehabilitation of the lower limbs

The article describes the main stages of developing a robotic system for the rehabilitation of the lower limbs based on the “tripteron” robot. The structure of a robotic system has been designed, consisting of a 3-PRRR parallel mechanism, which provides the angles of rotation of all joints of the patient’s leg required for rehabilitation and a passive orthosis for supporting the limb. At the first stage, the positions of the active mechanism links are determined. The output link of only one kinematic chain, making a translational movement in the vertical direction, will experience a maximum load. A design diagram of this kinematic chain was built, and the reactions of the supports were determined at the second stage. At the third stage, kinematic dependences were obtained, and an engine was selected that would provide the required torque at the required speeds.

Passive Knee Orthoses Assistance in Functional Electrical Stimulation Cycling in an Individual With Spinal Cord Injury

Functional Electrical Stimulation (FES) may be used in rehabilitation and assistance of people with Spinal Cord Injury (SCI). One significant application is facilitating physical exercise, mainly when combining FES with mechanical platforms, such as tricycles. However, there are still technical challenges in FES cycling protocols, such as improving control and cycling performance. Here we show how passive elements in knee orthoses during FES cycling could increase the average cadence, taking advantage of the cycling movement. Our approach is twofold. First, we simulated the forward dynamics of a detailed musculoskeletal model with passive elements over the knees. Simulations showed that specific spring stiffness ranges increased the crankset speed during cycling by more than 50%. Using parameters found in simulations, we built a pair of passive orthoses and performed experiments with one individual with SCI. During two days, the volunteer cycled with similar stimulation magnitude with and without the passive elements. We observed that the average crankset speed was higher by more than 10% when the springs were attached to the passive orthoses. These results show the potential of using passive elements to increase cycling speed for FES cycling with similar or even lower stimulation magnitude, leading to longer exercise duration.

Stability Limits for Vertical Vibrations of Paraplegic Subjects while Using Passive Orthosis

Spinal cord injury (SCI) subjects use passive orthosis to assist them with the postural balance in daily life. Vertical vibrations are used to improve the postural balance of theses patients, mainly in terms of whole-body-vibrations, as in therapies. It is noteworthy to understand in what situation these patients are able to tolerate vertical vibrations while wearing orthosis. The main focus of this paper is to model vertical vibrations in the postural balance of arm free standing of the paraplegic subjects who use passive orthosis, and, mathematically understand the stability limits for these vibrations. To find the stable amplitudes and frequencies, equations of motions of the system are translated into non-homogeneous Mathieu equations, which are then analytically solved and the results are numerically plotted. In addition, the effect of shoe stiffness on the amplitude and frequency of the vibrations which violate stability are studied. The results show to be sure of the stability of the paraplegics in vertical vibrations, the shoe sole of the orthosis should have high values of stiffness, and this will guarauntee bigger ranges of stable vibrations and safer stance for the patients. Using the results, one can interpret how a paraplegic subject with passive orthosis may react to vertical perturbations, meaning, what ranges of frequencies and amplitudes of perturbations is tolerable without losing stability. This study is one of the necessities in designing new passive orthosis with more stability when exposed to perturbations.

Identification of the parallel 3-PRRR manipulator parameters considering the workspace boundaries and the passive orthosis movements

The article discusses a system of rehabilitation of the lower extremities based on a passive orthosis in the form of a sequential RRRR mechanism and an active parallel 3-PRRR robot. Effective numerical methods and algorithms were developed and tested that made it possible to determine the minimum geometric parameters of the active parallel mechanism that ensure the movement of a passive orthosis within the working area in accordance with clinical data when simulating walking. The simulation results are presented by visualizing the exported workspaces in the STL format.

Design of a lightweight passive orthosis for tremor suppression

BackgroundTremor is the most common movement disorder with the highest prevalence in the upper limbs. The mechanical suppression of involuntary movements is an alternative and additional treatment to medication or surgery. Here we present a new, soft, lightweight, task asjustable and passive orthosis for tremor suppression.MethodsA new concept of a manual, textile-based, passive orthosis was designed with an integrated, task adjustable, air-filled structure, which can easily be inflated or deflated on-demand for a certain daily activity. The air-filled structure is placed on the dorsal side of the wrist and gets bent and compressed by movements when inflated. In a constant volume air-filled structure, air pressure increases while it is inflating, creating a counterforce to the compression caused by bending. We characterised the air-filled structure stiffness by measuring the reaction torque as a function of the angle of deflection on a test bench. Furthermore, we evaluated the efficacy of the developed passive soft orthosis by analysing the suppression of involuntary movements in the wrist of a tremor-affected patient during different activities of daily living (i.e. by calculating the power spectral densities of acceleration).ResultsBy putting special emphasis on the comfort and wearability of the orthosis, we achieved a lightweight design (33 g). The measurements of the angular deflection and resulting reaction torques show non-linear, hysteretic, behaviour, as well as linear behaviour with a coefficient of determination (R2) between 0.95 and 0.99. Furthermore, we demonstrated that the soft orthosis significantly reduces tremor power for daily living activities, such as drinking from a cup, pouring water and drawing a spiral, by 74 to 82% (p = 0.03); confirmed by subjective tremor-reducing perception by the patient.ConclusionThe orthosis we developed is a lightweight and unobtrusive assistive technology, which suppresses involuntary movements and shows high wearability properties, with the potential to be comfortable. This air-structure technology could also be applied to other movement disorders, like spasticity, or even be integrated into future exoskeletons and exosuits for the implementation of variable stiffness in the systems.

АНАЛИЗ И КЛАССИФИКАЦИЯ РЕАБИЛИТАЦИОННЫХ РОБОТОТЕХНИЧЕСКИХ СИСТЕМ НА БАЗЕ ПАРАЛЛЕЛЬНЫХ МАНИПУЛЯТОРОВ

One of the most actual and complex problems of medicine and neurology is the rehabilitation of patients. Robotic systems currently occupy an important place in the comprehensive rehabilitation of neurological patients with severe motor impairment of various etiologies, as well as the most socially significant and common neurological diseases. The article discusses various architectures of robotic systems for the rehabilitation of the lower limbs. The article also analyzes the work of foreign scientists who deal with these issues. As a result, a classification of rehabilitation systems has been compiled and reviewed. The structure of the rehabilitation system based on a passive orthosis and active parallel 3-PRRR robot is proposed. A numerical algorithm has been developed to determine the workspace of a 3-PRRR robot, taking into account design limitations. The algorithm is based on the concept of non-uniform coverings using interval analysis methods and is implemented in the C++ programming language. The results of computational experiments are presented. The simulation results are visualized by converting a set of three-dimensional parallelepipeds into an STL file. However, many areas remain open to theoretical research. A further area of research is the optimization of the geometric parameters of the system for carrying out rehabilitation procedures.

Impact of knee joint loading on fragmentation of serum cartilage oligomeric matrix protein.

The aim of the study was to examine the effect of mechanical knee joint loading on the fragmentation pattern of serum cartilage oligomeric matrix protein (COMP). Ten healthy men ran with knee orthoses that were passive or active (+30.9 N·m external flexion moments) on a treadmill (30 minute; v = 2.2 m/s). Lower-limb mechanics, serum COMP levels, and fragmentation patterns (baseline; 0, 0.5, 1, 2 hours postrunning) were analyzed. Running with active orthoses enhanced knee flexion moments, ankle dorsiflexion, and knee flexion angles (P < .05). There was an increase in serum COMP (+25%; pre: 8.9 ± 2.4 U/l; post: 10.7 ± 1.9 U/l, P = .001), COMP pentamer/tetramer (+88%; 1.88 ± 0.81, P = .007), trimer (+209%; 3.09 ± 2.65, P = .005), and monomer (+78%; 1.78 ± 0.85, P = .007) after running with passive orthoses and in serum COMP (+41%; pre: 8.5 ± 2.7 U/l; post: 11.3 ± 2.1 U/l, P < .001), COMP pentamer/tetramer (+57%; 1.57 ± 0.39, P = .007), trimer (+86%; 1.86 ± 0.47, P = .005), and monomer (+19%; 1.19 ± 0.34, P = .114) after running with active orthoses. Increased fragmentation might indicate COMP release from cartilage while running. Interestingly, 0.5 h up to 2 hours after running with passive orthoses, trimer (0.5 hour: 2.73 ± 3.40, P = .029; 2 hours: 2.33 ± 2.88, P = .037), and monomer (0.5 hour: 2.23 ± 2.33, P = .007; 1 hour: 2.55 ± 1.96, P = .012; 2 hours: 2.65 ± 2.50, P = .009) increased while after running with active orthoses, pentamer/tetramer (1 hour: 0.79 ± 0.28, P = .029), and trimer (1 hour: 0.63 ± 0.14, P = .005; 2 hours: 0.68 ± 0.34, P = .047) decreased. It seems that COMP degradation and clearance vary depending on joint loading characteristics.

Simulation of the assistance of passive knee orthoses in FES cycling.

Although advances in technology promoted new physiotherapy approaches, there is still an urge for equipment and techniques to improve the quality of patients lives with motor disabilities. Functional electrical stimulation cycling (FES cycling) is an example of this type of technology, in which the control of stimulation parameters enables a spinal cord injured person to ride a bicycle. In this work, we aim to investigate the use of passive knee orthoses for FES cycling assistance. Hence, we compared the cycling cadence and quadriceps excitation using an FES cycling simulation platform for different spring torques and ranges. In this paper, we obtained spring parameters that increased cycling cadence by 10.60% while decreasing by 7.33% the quadriceps activity, which indicates that this type of passive orthosis may diminish fatigue caused by FES.

Human Evaluation of Wheelchair Robot for Active Postural Support (WRAPS)

SummaryPeople with severe neuromuscular trunk impairment cannot maintain or control upright posture of the upper body in sitting while reaching. Passive orthoses are clinically available to provide support and promote the use of upper extremities in this population. However, these orthoses only position the torso passively without any degree of trunk movement.We introduce for the first time a novel active-assistive torso brace called Wheelchair Robot for Active Postural Support (WRAPS). It consists of two rings over the hips and chest connected by a 2RPS-2UPS parallel robotic device. WRAPS can modulate the displacement of the upper ring and/or the forces applied on the torso through the ring in four degrees-of-freedom (DOF), including rotations and translation in the sagittal and frontal planes.In the present study, we evaluate the design of WRAPS and its functions. Moreover, we discuss the potential effectiveness of WRAPS as a therapeutic robotic tool in people with severe trunk control deficits. The performance of WRAPS was evaluated in seated healthy subjects. Kinematics and surface electromyography (sEMG) were collected when the participants performed selective trunk movements. First, the torso range of motion (tROM) was calculated with WRAPS in transparent mode—zero-force control mode—which was compared with free-guided tROM (no WRAPS) with motion capture system. Second, a position control mode was configured to mobilize the torso along the trajectories obtained with the transparent mode.Our results show that the design of WRAPS suited well the subject’s anthropometrics while supporting the weight of the torso. Importantly, WRAPS can be programmed to replicate the subject’s tROM, without the full activation of torso muscles. This can be critical in individuals with no trunk control. Altogether, these preliminary results indicate the potential applicability of WRAPS to promote active-assistive trunk mobility in people who cannot sit independently because of trunk dysfunction.

Polymer optical fiber-embedded, 3D-printed instrumented support for microclimate and human-robot interaction forces assessment

This paper presents the fabrication, characterization and applications of a 3D-printed instrumented support for wearable devices. Intensity variation-based polymer optical fiber (POF) sensors were employed in the support instrumentation, in order to obtain a low-cost system. In the proposed instrumented support, two POFs are embedded in a 3D-printed acrylonitrile butadiene styrene (ABS) rigid structure for microclimate assessment (without the influence of the applied force). Additionally, other two POFs are embedded in a thermoplastic polyurethane (TPU) flexible structure for the force assessment, where one sensor measures the applied force in flexion cycles and the other in extension cycles. All four sensors are characterized with respect to temperature and humidity. Both force sensors are also characterized with respect to the force and their cross-sensitivities with respect to the temperature and humidity. The results show the feasibility of the proposed sensor system embedded in the 3D-printed support, where the errors for the force assessment are below 2.8 N, and for temperature and humidity the errors are about 1.1 °C and 2.5%, respectively. The feasibility of the proposed instrumented support in measuring force and microclimate variations was also verified in the application as a shank support for a lower limb exoskeleton for knee rehabilitation and on a passive orthosis for gait assistance.