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The knee joint performs a significant amount of positive or negative mechanical work during gradient walking, and targeted assistance during periods of high mechanical work could yield strong human augmentation benefits. This paper explores the biomechanical effects of providing knee extension assistance during the early stance phase of the gait cycle using a powered unilateral knee exoskeleton during gradient walking on able-bodied subjects. Twelve subjects walked on 15% gradient incline and decline surfaces with the exoskeleton providing knee extension assistance during the early stance phase of the gait cycle. For both incline and decline walking, the exoskeleton assistance reduced the muscle activation of the knee extensors on the assisted leg ( ${p} ). However, only approximately half the individuals responded to exoskeleton assistance positively by reducing their metabolic cost of walking for both incline and decline tasks. The results indicate that, unlike the individuals who did respond, the individuals who did not respond to the assistance may have penalized their metabolic cost by their biomechanical compensatory behaviors from the unassisted leg.

Objective: This paper aims to analyse the human musculoskeletal and energetic adaptation mechanisms when physically interacting with a unilateral knee orthosis during treadmill walking. Methods: Test subjects participated in two walking trials, whereby the orthosis was controlled to deliver five predefined torque profiles of different duration (as % of a gait cycle). The adaptations to assistive torques of different duration were analysed in terms of gait parameters, metabolic effort, and muscle activity. Results: Orthotic assistances kinematic effects remain local to the assisted leg and joint, unlike the muscles spanning the knee joint, which engage in a balancing-out action to retain stability. Duration of assistive torque significantly affects only the timing of the knee joints peak flexion angle in the stance phase, while the observed joint kinematics and muscle activity demonstrate different recovery times upon changing robotic support (washout effects). Conclusion: Human body adaptations to external robotic knee joint assistance during walking take place on multiple levels and to a different extent in a joint effort to keep the gait stable. Significance: This paper provides important insights into the human bodys multiple adaptation mechanisms in the presence of external robotic assistance.

It is yet not known whether the variation in knee orthotics pressure would lead to changes in muscle activity during-sit-to-stand postural transition in patients with knee osteoarthritis (OA). Participants in this analytical study were patients with knee OA. The research design was a cross-sectional study. They were enrolled in the study through a sample of convenience method. The primary outcome measure was surface electromyography for measuring muscle activity while changing knee orthotics pressure during sit-to-stand motion. Data were summarized with mean and standard deviation while Friedman’s test was performed for multiple comparison of variables, at a significance level of p = 0.05. Seven elderly patients with knee osteoarthritis (mean age 71.4 ± 11.8 years) participated in the study. Moderate orthotics (7.3 mmHg) led to a significant increase in the percentage maximum voluntary contraction (MVC) of tibialis anterior compared to that obtained without orthotics. Rectus femoris, vastus medialis, vastus lateralis, and biceps femoris tended to increase the % MVC with an increase in wearing pressure. It was therefore concluded that the muscle activity during sit-to-stand motion could be increased in patients with knee osteoarthritis by wearing flexible orthotics with varying pressure.

[Purpose] To investigate the effects of a flexible brace, by analyzing whether its usage; the difference in wearing pressure could change the joint position sensation in healthy participants; and develop a flexible knee brace for patients with knee osteoarthritis. [Participants and Methods] The study included eight healthy males with 14 knee joints (mean age, 22.0 ± 3.1 years). To measure joint position sense, an "angle reproduction test" was performed in three experimental conditions: 1) participants not wearing the brace, 2) the brace was secured with an appropriate force, and 3) the brace was fully secured using hook-and-loop fasteners. [Results] No significant difference was observed among groups comprising of those not wearing, those wearing with the standard force, and those wearing with the tight force. When the maximum hook-and-loop fastener was squeezed, the sensory error in joint position was maximized at both 30° and 60° flexion. [Conclusion] Joint position sense improvement was confirmed to be poor by orthosis, and an error occurred in the joint position sense by increasing the wearing pressure in orthosis. In future, measurements should be performed on patients with knee osteoarthritis who have decreased joint position sense and verify the effect of different wearing pressures verified.

Objective In normal walking, the ground reaction forces pass through the medial compartment of the knee and produce an external adduction torque around the knee joint. External adduction moment of the knee can lead to medial knee osteoarthritis. Adjustment of the knee alignment and modifying the biomechanical forces on the knee can reduce pain, increase performance, and parameters of walking and improve the quality of life. The use of knee orthoses is recommended to remove weight from the affected compartment and reduce pain in patients with knee osteoarthritis. However the effect of the knee orthosis height on external adduction moment and abduction force has not been measured in previous studies, so the purpose of this study was to assess of the new three-point pressure knee orthosis (e-life) on the mentioned parameters in the patients with mild to moderate knee osteoarthritis Materials & Methods The study subjects were 10 patients (9 females, 1 male) with mild to moderate knee Osteoarthritis (OA) that after receiving OA 2 or 3 degree by a specialist, were referred to the Rehabilitation Research Center of the Faculty of Rehabilitation. Each subject spent five different conditions in the study. Ordering and sequencing of the process was done through randomization for each individual. These five stages included no orthosis, orthosis with long lift length, common-loaded orthosis, medium-angle abdominal orthosis, and maxillary abdominal orthosis. In this study, a three-dimensional QTM motion analysis system (Version 7.2, made in Sweden) with seven 100-kHz camera (Produced by Qualisys, USA) and one Kistler force detection plate (500×600 mm, model AA 9260, manufactured by Kistler, Switzerland) was used to collect the kinetic and kinematic data variables of walking at the Musculoskeletal Research Center of Isfahan University of Medical Sciences. Visual 3D software (C-Motion USA Version 4) was used to musculoskeletal modelling of the lower limb. The temporal and spatial parameter, the moments applied to knee joint and knee range of motion were measured for each individual at all stages. SPSS (version 22) was used for data analysis and Shapiro-Wilk test to verify the normal distribution of data. The repeated-measures ANOVA test was used to compare the effect of orthosis on the parameters mentioned before and after the use of knee orthosis. Results Spatial parameters did not show significant differences (P>0.05). There was no significant difference between the range of motion in all three pages in different orthodontic states (P>0.05). The maximum extensor torque was applied to the knee joint without brace, but the results of statistical analysis did not show any significant difference (P>0.05). Adductor torque was significantly lower in orthosis with a lower lever arm than without brace (P

A number of passive orthoses have been developed to provide gait assistance and rehabilitation for individuals who have lost the ability to walk. However, the required metabolic cost for legged mobility with conventional orthoses is huge, preventing its daily use. Using the forces/torques generated by external actuators is one of the effective ways to solve the problem induced from the considerable effort required for orthotic gait. For that, design of a compact, efficient and light weight actuation system and its delicate control are required. In Chapter 1, Powered Reciprocating Hip Orthosis, a novel hip actuator making use of the coupling hip mechanism of the reciprocating gait orthosis (RGO) is proposed. The RGO, a wearable and passive orthosis, provides paralyzed patients with hands-free standing and the ability for dynamic ambulation without any external actuation. Therefore, the mechanism of the RGO can be utilized effectively for improving the hip actuator design for a powered lower limb orthosis. Starting with this motivation, a powered limb orthosis combined with the conventional RGO was designed and its control structure was implemented on a paraplegic subject (T12 complete). First, a dynamic analysis is presented to identify and better understand the potential use of the RGO mechanism. For the analysis, the simple RGO dynamic model at a single support phase is obtained and its equations of motion are derived using Lagrange's equations of motion. Through the physical interpretation provided by the inverse dynamics, it is proved that the required maximum hip torque for stance phase is significantly decreased when the RGO hip coupling mechanism is applied. An unproved torso stability provided by the design is also investigated. Subsequently, overall control structure with a user-interface module is introduced to provide basic functions to the powered orthosis for locomotion. While implementing the designed orthosis with the human subject, a difficult problem on the dorsiflexion-activated passive knee orthosis of the conventional RGO is discussed and leads to Chapter 2: Friction Damping Control Knee Orthosis. A simple, but effective, microprocessor orthotic knee control method is presented with a novel knee joint design and an inertial measurement unit (IMU) sensor in Chapter 2. First, an electric hardware and a control structure with the IMU sensor are introduced. Next, to understand the knee dynamics and determine a control strategy, a lower extremity model is set up. Using this model, a dynamic analysis for ballistic walking with overshooting and circumduction of the hip joint motion, and downstairs walking is executed with the experimental hip motion data. Based on the observations for human hip joint motion and the obtained dynamic simulation results, a friction damping control method is proposed. Its implementation enables natural walking on level ground and provides the appropriate resistance of the knee joint in downstairs walking for assistance and safety to normal human subjects using the designed knee orthosis.

Knee orthosis is commonly used in supporting the knee movement and protecting the anterior cruciate ligament (ACL) injuries from worsening. In clinical practices, there are many types of ready-made orthoses that available in the market. However, different types of orthoses may provide different performances for patient’s knee joint. Therefore, this paper attempt to investigate the performance of knee orthoses for ACL-injured knee. Two groups took part in the study; (Group 1) six ACL-injured, (Group 2) four healthy participants, where two types of knee orthoses were adopted; (Brace 1) hinge brace, (Brace 2) sleeve brace with bilateral hinges. The knee joint motions were calculated using kinematics data while comfortability was conducted through surveys. From the findings, Brace 1 produced normal range of motion (ROM) for internal rotation at 5.47° while Brace 2 fall outside of the normal range at 2.165°. Meanwhile, the external rotation for Brace 1 (-13.25°) was lower than Brace 2 (-33.25°). Furthermore, the comfortability analysis suggested that Brace 1 (60%) was more effective than Brace 2 (40%). To conclude, Brace 1 portrayed optimal performance than Brace 2 during dynamic balance activities with reduction in ROM to prevent excessive knee rotation.

This paper presents the mechatronic design and initial validation of a partial-assist knee orthosis for individuals with musculoskeletal disorders, e.g., knee osteoarthritis and lower back pain. This orthosis utilizes a quasi-direct drive actuator with a low-ratio transmission (7:1) to greatly reduce the reflected inertia for high backdrivability. To provide meaningful assistance, a custom Brushless DC (BLDC) motor is designed with encapsulated windings to improve the motor’s thermal environment and thus its continuous torque output. The 2.69 kg orthosis is constructed from all custom-made components with a high package factor for lighter weight and a more compact size. The combination of compactness, backdrivability, and torque output enables the orthosis to provide partial assistance without obstructing the natural movement of the user. Several benchtop tests verify the actuator’s capabilities, and a human subject experiment demonstrates reduced quadriceps muscle activation when assisted during a repetitive lifting and lowering task.

[Purpose] The Robotics Knee Orthosis (RKO) is a knee-ankle-foot orthosis with active robot assisting technology. The purpose of this study is to examine the effects of exercise with the RKO (RKO-exercise) in stroke patients with hemiplegia. [Subjects and Methods] Participants were nine stroke patients with hemiplegia, residing in a convalescent rehabilitation ward. The duration of the RKO-exercise program was 10 days. Participants were evaluated three times prior to intervention, once after intervention, and one month post intervention. Each session consisted of standard-of-care physical therapy for 60 minutes and RKO-exercise for 20 minutes. Dependent variables were 10-meter gait speed, cadence, Berg Balance Scale (BBS) score, stride length, the absolute value of left-right symmetry of the step length, and one-leg support period while walking. Data were analyzed using a one-way repeated measures ANOVA. [Results] Stride length, left-right symmetry of the step length, and one-leg support period while walking changed following the RKO exercise program. 10-meter walking speed, cadence, percentage of one-leg support period (affected side), and BBS changed significantly at one month post treatment time points. [Conclusion] It is expected that RKO-exercise helps recovery process after the stroke. RKO-exercise effectively treats impaired mobility in patient status-post stroke.

In this study, three knee-orthoses (dial lock type, medium size, right side) were used for a quality level test (static bending test and solidity test of the locking system) of the knee-orthosis locking system. In the static bending test, a smaller maximum load was observed in samples A and C compared to the reference standard value(KS P 8408 standard value: 1000 N, sample A: 865 N, sample C: 833 N). In addition, in the solidity test of thelocking system, a smaller maximum load was observed in the all samples compared to the referenced standard value(KS P 8411 standard value: 200 N, sample A: 41 N, sample B: 97 N, sample C: 54 N). Korean industrial standardsfor knee-orthoses and systematic test methods are lacking. Therefore, a systematic management plan for knee-orthosesis required. The result of the current study showed that a systematic management plan for the knee-orthosis lockingsystem is required. In particular, the development of a quantitative and objective test method is needed. The findingsof the current study may be useful for monitoring the quality of the knee-orthosis locking system and may providefoundational information for the development of a quantitative and objective test method.

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 significantly increased pelvic obliquity (2.79°, p

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.

The goal of this study is the assessment of an assistive control approach applied to an active knee orthosis plus a walker for gait rehabilitation. The study evaluates post-stroke patients and healthy subjects (control group) in terms of kinematics, kinetics, and muscle activity. Muscle and gait information of interest were acquired from their lower limbs and trunk, and a comparison was conducted between patients and control group. Signals from plantar pressure, gait phase, and knee angle and torque were acquired during gait, which allowed us to verify that the stance control strategy proposed here was efficient at improving the patients’ gaits (comparing their results to the control group), without the necessity of imposing a fixed knee trajectory. An innovative evaluation of trunk muscles related to the maintenance of dynamic postural equilibrium during gait assisted by our active knee orthosis plus walker was also conducted through inertial sensors. An increase in gait cycle (stance phase) was also observed when comparing the results of this study to our previous work. Regarding the kinematics, the maximum knee torque was lower for patients when compared to the control group, which implies that our orthosis did not demand from the patients a knee torque greater than that for healthy subjects. Through surface electromyography (sEMG) analysis, a significant reduction in trunk muscle activation and fatigability, before and during the use of our orthosis by patients, was also observed. This suggest that our orthosis, together with the assistive control approach proposed here, is promising and could be considered to complement post-stroke patient gait rehabilitation.

International audience; This study is devoted to investigate the influence of a knee orthosis for human walking by using a mathematical model for a 7-links planar biped-composed with two identical legs, two feet and one trunk-with an orthosis attached to both thigh and calf, during walking. In the first part, we design a cyclic walking gait in the sagittal plane for human without the orthosis. The second part we consider that the human looses his muscular possibilities in one of his knees. To overcome his handicap the human is equipped of a knee orthosis. We analyse the positive effect of the orthosis over the assisted knee to track the previous designed reference trajectory. By using at each time an optimisation algorithm, we minimise the torques provided by the human. The numerical tests confirm the possibility to reduce the torque produced in the disabled knee. The next step is to take into account explicitly an information from EMG signal during a walking to modulate the power of the orthosis.

International audience; The knee is the largest joint in the body and supports high loads, up to several times the body weight. It is vulnerable to injury during sport or professional activities, potentially leading to chronic knee instability. This instability is a functional issue to the patient and is characterized by a “wobbly” feeling. Different internal structures take part in joint stabilization by passive (ligaments, capsule) or active (neuro-muscular system and proprioception) action. The most common injury involves the anterior cruciate ligament (ACL) complete or partial rupture: it is involved in 24% of all knee injuries and 59% of ligamentous injuries [1]. In the United States,the annual incidence in the general population is approximately 1 in 3500 with 100,000 ACL reconstructions performed each year [2, 3]. These conditions are a huge burden on individualsand healthcare systems. Diagnosis of knee instability involves a discussion with the patient and a clinical examination, usually the Lachman test. It consists in a manual anterior translation of the tibia aiming at putting the ACL in tension. By practice, the examiner is able to grade the laxity by severity [4]. However, its sensitivity and specificity to detect complete ACL ruptures depends on the experience of the examiner, the patient’s body type and the delay between the accident and examination [5]. In order to reduce this variability, arthrometers were developed.These devices apply an increasing force to induce a postero-anterior drawer and measure the corresponding translation. Displacement-load curves of the healthy and injured knees are compared; ACL rupture is ascertained when differential laxity is higher than a certain threshold. Well-known arthrometer devices are the KT-1000 developed by [6] and the GNRB® [7]. The former is very popular and has been widely studied; its sensitivity to detect complete ACL ruptures is 77% and its specificity 90% (threshold: differential laxity of 3 mm at 130 N). Thelatter was developed recently; two studies [5, 7] highlighted the superiority of this device compared to similar apparatus. A differential threshold of 3 mm at 134 N is used to determine complete rupture: its sensitivity is 70% and specificity 99%. This arthrometer device is also used to diagnose partial ruptures (threshold of 1.5 mm at 134 N) with a sensitivity of 80% and a specificity of 87%.Knee braces or orthoses are usually part of the standard therapy for knee instability and are commonly prescribed by physicians and medical practitioners. Their claimed mechanical effects are to support/align the joint and increase proprioceptive input [8]. However, very few studies actually show significant actions, from biomechanical studies to therapeutic trials [9, 10]. Mechanical/ physiological effects have been emphasized, but the mechanisms of action have been poorly characterized [8, 9, 10, 11, 12, 13]. What is more, subjective evaluations of patients highlight a large demand for these products; therefore, their efficiency is still widely discussed among medical experts. In particular, therelative importance of the two principal stabilizing mechanisms is not known:- joint stiffening by adding supporting structures, e.g. hinged bars secured to the joint by straps and fabric (passive mechanism)- neuromuscular control enhancement by proprioceptive effect (active mechanism)As a consequence of these uncertainties, medical practitioners and manufacturers still lack a simple evaluation tool for knee orthoses. A French committee of experts highlighted this problem [14] and stated that orthoses must be evaluated by taking both the mechanisms of action and the desired therapeutic effects into account.Although the passive action of knee braces to prevent a drawer motion has already been characterized on surrogate limbs [15, 16, 17], only one attempt has been made to link these measures to corresponding expected in-vivo actions through numerical modelling [18, 19], highlighting a passive stiffening much lower than what is brought by intact ligaments. However, a real clinical study is still needed to validate the numerical results and investigate the influence of patient-specific factors such as morphology, injury severity, neuromuscular adaptation and instability feeling control.This study is aimed at objectively quantifying the joint stiffening action of various commercial braces in-vivo using a GNRB® arthrometer on a number of pathological patients.

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.

Existing robotic transtibial prostheses provide only ankle joint actuation and do not restore biarticular function of the gastrocnemius muscle. This paper presents the first powered biarticular transtibial prosthesis, which is a combination of a commercial powered ankle-foot prosthesis and a motorized robotic knee orthosis. The orthosis is controlled to emulate the human gastrocnemius based on neuromuscular models of matched nonamputees. Together with the ankle-foot prosthesis, the devices provide biarticular actuation. We evaluate differences between this biarticular condition and a monoarticular condition with the orthosis behaving as a free-joint. Six participants with transtibial amputation walk with the prosthesis on a treadmill while motion, force, and metabolic data are collected and analyzed for differences between conditions. The biarticular prosthesis reduces affected-side biological knee flexion moment impulse and hip positive work during late-stance knee flexion, compared to the monoarticular condition. The data do not support our hypothesis that metabolism decreases for all participants, but some participants demonstrate large metabolic reductions with the biarticular condition. These preliminary results suggest that a powered artificial gastrocnemius may be capable of providing large metabolic reductions compared to a monoarticular prosthesis, but further study is warranted to determine an appropriate controller for achieving more consistent metabolic benefits., United States. National Aeronautics and Space Administration (Grant NNX12AM16G)

International audience; Objective: To develop a decision-making tool (DMT) to facilitate the prescription of knee orthoses for patients with osteoarthritis (OA) in daily practice. Methods: A 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 withprimary-and secondary-carephysicians, 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. Results: The 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/conclusion: Based 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. (C) 2018 The Author(s). Published by Elsevier Masson SAS.

International audience; This paper proposes a mathematical model for a 7-links an-thropomorphic biped-composed with two identical legs, two feet and one trunk-with an orthosis attached to both thigh and calf, during walking. We consider a cyclic walking gait in the sagittal plane. In the first part, we obtain trajectories of the motion for different walking speeds. It confirmed the fact that much more torque is recquired in the stance leg than in the swing leg. The second part analyses the impact of an ortho-sis, which fully assists the knee over the walking. Simulations point out the fact that valid joints have to compensate the weight of the orthotic system and show the interest to assist the knee of the stance leg.

Physical changes such as leg length discrepancy, the addition of a mass at the distal end of the leg, the use of a prosthetic, and stroke frequently result in an asymmetric gait. This paper presents a metric that can potentially serve as a benchmark to categorize and differentiate between multiple asymmetric bipedal gaits. The combined gait asymmetry metric (CGAM) is based on modified Mahalanobis distances, and it utilizes the asymmetries of gait parameters obtained from motion capture and force data recorded during human walking. The gait parameters that were used in this analysis represent spatio-temporal, kinematic, and kinetic parameters. This form of a consolidated metric will help researchers identify overall gait asymmetry by showing them if the overall gait symmetry is improving and avoid the case where one parameter's symmetry is improving while another is getting worse. The CGAM metric successfully served as a measure for overall symmetry with eleven different gait parameters and successfully showed differences among gait with multiple physical asymmetries. The results showed that mass at the distal end had a larger magnitude on overall gait asymmetry compared to leg length discrepancy. It also showed that the combined effects are varied based on the cancelation effect between gait parameters. The metric was also successful in delineating the differences of prosthetic gait and able-bodied gait at three different walking velocities.

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., Massachusetts Institute of Technology. Media Laboratory

Several conservative treatments for medial knee osteoarthritis such as knee orthosis and laterally wedged insoles have been shown to reduce the load in the medial knee compartment. However, those treatments also present limitations such as patient compliance and inconsistent results regarding the treatment success.To analyze the effect of an ankle-foot orthosis on the knee adduction moment and knee joint alignment in the frontal plane in subjects with knee varus alignment.Controlled laboratory study, repeated measurements.In total, 14 healthy subjects with knee varus alignment were analyzed in five different conditions: without orthotic, with laterally wedged insoles, and with an ankle-foot orthosis in three different adjustments. Three-dimensional kinetic and kinematic data were collected during gait analysis.Significant decreases in knee adduction moment, knee lever arm, and joint alignment in the frontal plane were observed with the ankle-foot orthosis in all three different adjustments. No significant differences could be found in any parameter while using the laterally wedged insoles.The ankle-foot orthosis was effective in reducing the knee adduction moment. The decreases in this parameter seem to be achieved by changing the knee joint alignment and thereby reducing the knee lever arm in the frontal plane.This study presents a novel approach for reducing the load in the medial knee compartment, which could be developed as a new treatment option for patients with medial knee osteoarthritis.