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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.

Robotic gait rehabilitation devices enable more efficient and convenient gait rehabilitation by mimicking the functions of physical therapists. In manual gait rehabilitation training, physical therapists try for patients to practice and memorize normal gait patterns by applying assistive torque to the patient's joint if the patient's gait deviates from the normal gait. Thus, it is one of the most important factors in the robotic gait rehabilitation devices to determine the amount of assistive torque to practice the normal gait. In this paper, the gait rehabilitation strategy inspired by an iterative learning algorithm is proposed which uses the cyclic and repetitive characteristic of gait motions. In the proposed strategy, the amount of assistive torque in the current stride is calculated based on the information in the previous stride. The simulation results with human models, and experimental results using an active knee orthosis are presented, which verify that the proposed strategy can generate appropriate torque to practice the knee motions for the normal gait.

Stance control knee orthoses (SCOs) have become very popular recently. However, there is little information regarding opinions of actual orthosis users. The purpose of this study was to quantify the users' opinions of a SCO, and see whether factors found important for knee orthoses in past studies hold true for a stance control orthosis as well. A standardized survey was employed as part of a larger field trial study of the Dynamic Knee Brace System, a SCO developed by the authors. The Dynamic Knee Brace System scored well in areas of effectiveness, operability, and dependability, but areas in need of improvement included weight, cosmesis, and donning and doffing. These findings match well with previous knee orthosis studies. This study shows that wearing a stance control knee orthosis can be a positive experience for an orthosis user.

Objective To develop an algorithm to help orthosis prescription for knee osteoarthritis patients. Material/Patients and methods Systematic review of the literature using a qualitative analysis on Pubmed databases, Cochrane Library and Pedro from 1966 to 2015, using the keywords “knee osteoarthritis”, “orthosis” with recommendations and highest quality trials. Development of a preliminary version of the algorithm using data from the literature and taking into account experience of different health professionals involved in the management of osteoarthritis patients. Validation of the algorithm by an international multidisciplinary expert college (PMR and sport medicine physician, rheumatologist, general practitioner, orthopaedic surgeon, physiotherapist, methodologist). New adaptations to obtain an acceptable final version. Results Elastic braces may be proposed in addition to the first-line non-pharmacological treatment (information/education, exercise and physical activity, weight reduction). Secondary a biomechanical analysis may be needed to provide a more rigid brace taking into account: the topography of pain, the lower limb static (varus/valgus), stability, any deformation reducibility. For unicompartimental OA, one can propose an unicompartmental discharge brace; a hinged stabilizing brace for bicompartmental OA with or without instability. For patellofemoral OA we can offer an orthotic with specific patellar device, Discussion/Conclusion Using an original methodology has produced an applicable algorithm in routine. A prospective validation in primary and secondary care to thirty patients is needed followed by an evaluation of the implementation of a wide range of health professionals in order to definitely validate the algorithm.