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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.

This study was conducted to analyze whether internal (IR) and external (ER) rotator shoulder muscles weakness and/or imbalance collected through a preseason assessment could be predictors of subsequent shoulder injury during a season in handball players. In preseason, 16 female elite handball players (HPG) and 14 healthy female nonathletes (CG) underwent isokinetic IR and ER strength test with use of a Con-Trex® dynamometer in a seated position with 45° shoulder abduction in scapular plane, at 60, 120 and 240°/s in concentric and at 60°/s in eccentric, for both sides. An imbalanced muscular strength profile was determined using -statistically selected cut-offs from CG values. For HPG, all newly incurred shoulder injuries were reported during the season. There were significant differences between HPG and CG only for dominant eccentric IR strength, ER/IR ratio at 240°/s and for IRecc/ERcon ratio. In HPG, IR and ER strength was higher, and ER/IR ratios lower for dominant than for nondominant side. The relative risk was 2.57 (95%CI: 1.60-3.54; P

Resume Objectifs La blessure en sport a un retentissement non negligeable sur la pratique sportive, mais aussi dans la vie quotidienne. Bien que l’athletisme soit connu de tous et pratique sur les cinq continents, tres peu de donnees epidemiologiques sur la frequence, l’incidence, la typologie ou les facteurs de risque des blessures en athletisme sont actuellement disponibles. Dans ce contexte, une reflexion concernant les strategies de prevention de la blessure en athletisme doit etre menee. Actualites La surveillance et le recueil des blessures en sport, par les etudes epidemiologiques, constituent une etape prealable indispensable dans la demarche de recherche clinique sur la prevention de la blessure en sport. Cette demarche doit s’appuyer sur une methodologie consensuelle et validee. Actuellement, les lesions de l’appareil locomoteur liees a la pratique de l’athletisme sont frequentes. La grande diversite de ces lesions reflete la diversite des disciplines, les contraintes etant differentes entre les disciplines explosives (sprints, haies, sauts, lancers) et les disciplines d’endurance (demi-fond, fond). On note ainsi une predominance des lesions musculaires de la cuisse et surtout des ischiojambiers dans les disciplines de sprint/haies, des tendinopathies d’Achille en sauts et sprint/haies et des lesions chroniques des genoux et fractures de fatigue en demi-fond et fond. Conclusion Des mesures de prevention specifiques ciblees sur les pathologies les plus frequentes doivent etre instaurees. Mais, dans le contexte ou ces donnees apparaissent encore insuffisantes pour bien apprehender la specificite des pathologies en fonction des disciplines, et pour comprendre les facteurs de risque et mecanismes lesionnels, la realisation d’etudes epidemiologiques prospectives et d’etudes ciblees sur certaines populations ou pathologies sont encore necessaires pour ameliorer les strategies de la prevention des blessures en athletisme.