Knee Orthosis Research Articles

Hip circumduction is not a compensation for reduced knee flexion angle during gait

It has long been held that hip abduction compensates for reduced swing-phase knee flexion angle, especially in those after stroke. However, there are other compensatory motions such as pelvic obliquity (hip hiking) that could also be used to facilitate foot clearance with greater energy efficiency. Our previous work suggested that hip abduction may not be a compensation for reduced knee flexion after stroke. Previous study applied robotic knee flexion assistance in people with post-stroke Stiff-Knee Gait (SKG) during pre-swing, finding increased abduction despite improved knee flexion and toe clearance. Thus, our hypothesis was that hip abduction is not a compensation for reduced knee flexion. We simulated the kinematics of post-stroke SKG on unimpaired individuals with three factors: a knee orthosis to reduce knee flexion, an ankle-foot orthosis commonly worn by those post-stroke, and matching gait speeds. We compared spatiotemporal measures and kinematics between experimental factors within healthy controls and with a previously recorded cohort of people with post-stroke SKG. We focused on frontal plane motions of hip and pelvis as possible compensatory mechanisms. We observed that regardless of gait speed, knee flexion restriction increased pelvic obliquity (2.8°, p < 0.01) compared to unrestricted walking (1.5°, p < 0.01), but similar to post-stroke SKG (3.4°). However, those with post-stroke SKG had greater hip abduction (8.2°) compared to unimpaired individuals with restricted knee flexion (4.2°, p < 0.05). These results show that pelvic obliquity, not hip abduction, compensates for reduced knee flexion angle. Thus, other factors, possibly neural, facilitate exaggerated hip abduction observed in post-stroke SKG.

A New Stance Control Knee Orthosis Using a Self-Locking Mechanism Based on a Planetary Gear Train

The objective of this work was to design and build a fully mechanical knee orthosis. A knee orthosis should both allow control of the angle of flexion of the knee during the stance phase of the gait cycle and leave the joint free during the swing phase. Knee orthoses are normally used to assist the walking of people suffering from muscle weaknesses or gait pathologies in order to avoid excessive knee flexion during the stance phase. The design of the orthosis proposed in the present work is characterized by allowing the knee to be locked at any angle of flexion during the stance phase, and because the orthosis can be unlocked to allow the joint to be released in the swing phase without the action of any external agent, i.e., without requiring external electrical or electronic systems for the control and performance of the orthosis. These characteristics mean that the design can be adapted to the gait of any user. The proposed design consists of a set of three rods, one attached to the user's thigh, another to the calf, and the other to the foot, connected to each other by a self-locking planetary gear train (PGT).

Evaluation of the Effect of the New Three Point Pressure Knee Orthosis on the Kinetic and Kinematic Parameters of the Patients With Mild to Moderate Knee Osteoarthritis

Evaluation of the Effect of the New Three Point Pressure Knee Orthosis on the Kinetic and Kinematic Parameters of the Patients With Mild to Moderate Knee Osteoarthritis

Examination of the intervention effect of the rehabilitation of the robotic knee orthosis

Examination of the intervention effect of the rehabilitation of the robotic knee orthosis

Knee Orthoses for Treating Patellofemoral Pain Syndrome.

Knee Orthoses for Treating Patellofemoral Pain Syndrome.

Modeling and control of an active knee orthosis using a computational model of the musculoskeletal system

One-third of the stroke survivors remain with some disability, needing assistance to perform the activities of daily life and therapy to recover the lost functions. The robotic rehabilitation is a promissed field in this context improving the effectiveness of the treatment. Many researches have focused on developing human-robot interaction control to ensure user safety and therapy efficiency, but the validation of these controllers often requires contact between humans and robots, which involves cost, time and risk of accidents. This work aims to present a computational model of an ideal active orthosis used to assist the knee movement as a tool for test and validate human-robot interaction controls. Three controllers were applied to make the orthosis move the knee tracking the desired trajectory: a PID controller, an Inverse Dynamics-Based controller, and a Feedback-Feedforward Controller. The model proved to be useful and the controller with the best performance was the Feedback-Feedforward one.

Design Evaluation in Novel Orthoses for Patients with Medial Knee Osteoarthritis.

Osteoarthritis of the knee is a debilitating condition affecting increasing numbers of individuals each year. One option for treatment is orthotic knee braces, but a little independent reviews have taken place to date on their relative outcomes for users. This study therefore evaluates the efficacy of different types of knee orthoses (braces) with regard to key aspects of use, including gait parameters, mobility and levels of comfort and compliance in subjects presenting with osteoarthritis (OA) of the knee. The collated data is presented with relevant supporting literature and appropriate descriptions in relation to each knee orthosis type that was identified, within appropriate subsections with advantages and disadvantages appropriately allocated. An analysis of each brace as presented by the corresponding article is then described further in terms of the design and structure, user outcomes and assessment summaries. According to the study carried out in this paper, it is presented and proved that applying the use of knee braces can reduce the knee adduction moment (KAM), but the amount of reduction afforded varies between designs. All of the studies reported significant pain reduction and functional improvement with the use of a knee brace, although their effect on the knee joint range of motion vary. Knee braces long-term use depends upon high levels of comfort and patient compliance, and further studies need to be conducted on larger numbers of subjects over greater time periods to reflect the long-term outcomes accurately

Development of a passive, wearable knee orthosis for the support of sit‐to‐stand movement with adaptive assistance moment

AbstractThe worldwide population aging and hence the higher risk of age‐related diseases facilitates interest in robotic devices for rehabilitation and movement assistance. A major factor of a persons functional independence is the ability to perform the movement task of standing up from a chair, also known as sit‐to‐stand (STS) movement. This work focuses on the development of a passive, wearable knee orthosis that supports the extension of the knee joint. As the knee flexes while sitting down a spring mechanism is loaded due to a cable wrapping around a deflection disc, thus generating a moment that assists standing up again. In order to prevent unintended knee extension this assistance moment should be minimized when the person is fully seated. To this end the geometry of the deflection disc, parametrized as B‐spline curve, is optimized in order to control the knee extension moment with respect to the knee angle. Initial tests with a first prototype show promising results.

Feasibility of an optimal EMG-driven adaptive impedance control applied to an active knee orthosis

This paper deals with EMG-driven torque estimation and optimal adaptive impedance control during robot-aided rehabilitation. In this preliminary and feasibility study, the proposed framework was evaluated considering an active knee orthosis and only healthy subjects. First, a simplified and optimized musculoskeletal model is used to compute the estimate of user’s torque considering electromyographic (EMG) signals taken from selected muscles acting during flexion and extension movements. The model optimization is performed by comparing the estimated torque from EMG with the torque generated by the inverse dynamics tool of the OpenSim software. As an alternative solution, a multilayer perceptron neural network (NN) is proposed to map the EMG signals to the user’s torque. The proposed approaches are evaluated by a set of healthy subjects wearing the knee orthosis and performing a protocol created for user–robot interaction analysis. Then, an EMG-driven adaptive impedance control is proposed to improve the user participation during the rehabilitation session. The approach is based on an optimal solution which considers the position error and the robot assistance level. The experimental results indicate the use of EMG signals is feasible for adaptive control strategies, taking into account the current condition of the user and optimizing the robot assistance.

Low-cost active knee orthoses – a systematic evaluation

Abstract The aging of humans induces muscle weakness. Muscle weakness results the inability to climb stairs or stand up from a chair and thus, is one of the first steps towards elderly having a less autonomous and self-sufficient life. Therefore, an accessible active knee orthosis, which especially supports these movements would be of great assistance. Recent research projects have focused on feasibility, perfection of motion control and imitation of human movement. For active knee orthoses to be accessible it must be affordable. Hence, this paper systematically evaluates the current research projects around active knee orthosis and discuss the possibilities of implementing a lowcost active knee orthosis.

Effect of lateral single bar knee orthoses in correction of genu varum in nutritional rickets

Genu varum (bowlegs) is a common paediatric deformity of knee presenting as physiological variation in growth pattern. Rickets lead to more pathological bowing if occurs during the phase of physiological bowing. Apart from vitamin D restoration orthotic management doesn’t form a part of standard treatment protocol for deformities due to rickets. It is a prospective & interventional randomised comparative study conducted at department of Physical Medicine & Rehabilitation at A.I.I.P.M.R. Mumbai. Patients presenting with clinical features of rickets with bilateral genu varum were screened. Sixty participants were enrolled in the study based on inclusion & exclusion criteria and divided into 2 groups (30 each) by lottery system. Group 1 received Stoss therapy for vitamin D restoration & bilateral lateral single bar knee orthosis. Group 2 received Stoss therapy only. Participants were assessed at initial visit and 2nd, 4th & 6th month after initiation of treatment with biochemical parameters, intercondylar distance (ICD) & radiographic tibio-femoral angle. Statistically significant decrease observed in intercondylar distance & tibio-femoral angle in both groups in subsequent follow-ups. Percentage change in intercondylar distance (58.75 vs. 56.59, P = 0.457) & tibio-femoral angle (right 56.74 vs. 55.49, P = 0.599; left 60.7 vs. 59.38, P = 0.666) at the end of 3rd follow-up on comparing both groups was statistically insignificant. Vitamin D restoration by Stoss therapy can be effectively used in treatment of genu varum in nutritional rickets with or without lateral single bar knee orthoses.

Effects of Prophylactic Knee Orthoses Use among Ice Hockey Players in Switzerland

Effects of Prophylactic Knee Orthoses Use among Ice Hockey Players in Switzerland

Effects of Prophylactic Knee Orthoses Use among Ice Hockey Players in Switzerland

Effects of Prophylactic Knee Orthoses Use among Ice Hockey Players in Switzerland

Dynamic Knee Orthosis System for Females with Anterior Cruciate Ligament Injuries

Dynamic Knee Orthosis System for Females with Anterior Cruciate Ligament Injuries

Gait Kinematics and Energy Expenditure of Users Walking with Semiflexion Knee-Ankle-Foot Orthosis: A Pilot Study

ABSTRACT Introduction The knee joint of a conventional knee-ankle-foot orthosis (KAFO) is locked during walking. This study aims to evaluate the effects of stance phase knee flexion on the kinematics, spatiotemporal parameters, and energy consumption of KAFO users. Materials and Methods A retrofitting drop lock that allows 12° of stance flexion in a single-axis knee joint was developed (called the semiflexion knee joint). Four subjects with quadriceps weakness volunteered to participate in the study. Gait analysis was conducted for the locked knee and the semiflexion knee orthosis using a calibrated eight-camera three-dimensional motion capture system. Preceding each trial, participants were given 5 days of gait training with the corresponding KAFO. Subjective feedback about the performance of the new KAFO was collected. Results Walking with the semiflexion KAFO did not significantly improve the speed (p = 0.161), cadence (p = 0.232), and stride length (p = 0.95) compared with walking with a locked KAFO. Although not significant (p = 0.132), trends of Physiological Cost Index (PCI) seemed to reduce in all subjects while walking with the semiflexion knee. Conclusions Using the KAFO with stance flexion did not significantly improve any of the locked knee gait parameters. However, there was a trend of reduction in the PCI score while walking with the semiflexion KAFO, and it also improved the ease of doing some activities of daily living.

Polymer optical fiber strain gauge for human-robot interaction forces assessment on an active knee orthosis

Abstract This paper presents the development of a polymer optical fiber (POF) strain gauge based on the light coupling principle, which the power attenuation is created by the misalignment between two POFs. The misalignment, in this case, is proportional to the strain on the structure that the fibers are attached. This principle has the advantages of low cost, ease of implementation, temperature insensitiveness, electromagnetic fields immunity and simplicity on the sensor interrogation and signal processing. Such advantages make the proposed solution an interesting alternative to the electronic strain gauges. For this reason, an analytical model for the POF strain gauge is proposed and validated. Furthermore, the proposed POF sensor is applied on an active orthosis for knee rehabilitation exercises through flexion/extension cycles. The controller of the orthosis provides 10 different levels of robotic assistance on the flexion/extension movement. The POF strain gauge is tested at each one of these levels. Results show good correlation between the optical and electronic strain gauges with root mean squared deviation (RMSD) of 1.87 Nm when all cycles are analyzed, which represents a deviation of less than 8%. For the application, the proposed sensor presented higher stability than the electronic one, which can provide advantages on the rehabilitation exercises and on the inner controller of the device.

A decision-making tool to prescribe knee orthoses in daily practice for patients with osteoarthritis

ObjectiveTo develop a decision-making tool (DMT) to facilitate the prescription of knee orthoses for patients with osteoarthritis (OA) in daily practice. MethodsA steering committee gathered a multidisciplinary task force experienced in OA management/clinical research. Two members performed a literature review with qualitative analysis of the highest-quality randomized controlled trials and practice guidelines to confirm evidence concerning knee orthosis for OA. A first DMT draft was presented to the task force in a 1-day meeting in January 2016. The first version of the DMT was criticized and discussed regarding everyday practice issues. Every step was discussed and amended until consensus agreement was achieved within the task force. Then 4 successive consultation rounds occurred by electronic communication, first with primary- and secondary-care physicians, then with international experts. All corrections and suggestions by each member were shared with the rest of the task force and included to reach final consensus. The final version was validated by the steering committee. ResultsThe definition and indication of several types of knee orthoses (sleeve, patello-femoral, hinged or unicompartmental offloading braces) were detailed. Orthoses may be proposed in addition to first-line non-pharmacological treatment if patient acceptance is considered good. At every step, a specific clinical assessment is needed. Discussion/conclusionBased on the latest high-level evidence, practice guidelines, and an expert panel, a DMT to facilitate daily practice prescription of knee orthoses for OA patients was designed. An evaluation of DMT implementation in a wide range of health professionals is still needed.

Postural adaptations to unilateral knee joint hypomobility induced by orthosis wear during gait initiation

Balance control and whole-body progression during gait initiation (GI) involve knee-joint mobility. Single knee-joint hypomobility often occurs with aging, orthopedics or neurological conditions. The goal of the present study was to investigate the capacity of the CNS to adapt GI organization to single knee-joint hypomobility induced by the wear of an orthosis. Twenty-seven healthy adults performed a GI series on a force-plate in the following conditions: without orthosis (“control”), with knee orthosis over the swing leg (“orth-swing”) and with the orthosis over the contralateral stance leg (“orth-stance”). In orth-swing, amplitude of mediolateral anticipatory postural adjustments (APAs) and step width were larger, execution phase duration longer, and anteroposterior APAs smaller than in control. In orth-stance, mediolateral APAs duration was longer, step width larger, and amplitude of anteroposterior APAs smaller than in control. Consequently, step length and progression velocity (which relate to the “motor performance”) were reduced whereas stability was enhanced compared to control. Vertical force impact at foot-contact did not change across conditions, despite a smaller step length in orthosis conditions compared to control. These results show that the application of a local mechanical constraint induced profound changes in the global GI organization, altering motor performance but ensuring greater stability.

Biomechanic and Energetic Effects of a Quasi-Passive Artificial Gastrocnemius on Transtibial Amputee Gait

State-of-the-art transtibial prostheses provide only ankle joint actuation and thus do not provide the biarticular function of the amputated gastrocnemius muscle. We develop a prosthesis that actuates both knee and ankle joints and then evaluate the incremental effects of this prosthesis as compared to ankle actuation alone. The prosthesis employs a quasi-passive clutched-spring knee orthosis, approximating the largely isometric behavior of the biological gastrocnemius, and utilizes a commercial powered ankle-foot prosthesis for ankle joint functionality. Two participants with unilateral transtibial amputation walk with this prosthesis on an instrumented treadmill, while motion, force, and metabolic data are collected. Data are analyzed to determine differences between the biarticular condition with the activation of the knee orthosis and the monoarticular condition with the orthosis behaving as a free-joint. As hypothesized, the biarticular system is shown to reduce both affected-side knee and hip moment impulse and positive mechanical work in both participants during the late stance knee flexion phase of walking, compared to the monoarticular condition. The metabolic cost of walking is also reduced for both participants. These very preliminary results suggest that biarticular functionality may provide benefits beyond even those of the most advanced monoarticular prostheses.

Design, control, and prototyping of a series elastic actuator for an active knee orthosis

Design, control, and prototyping of a series elastic actuator for an active knee orthosis