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Inertial measurement units (IMUs) allow for measurements of kinematic movements outside the laboratory, persevering the athlete-environment relationship. To use IMUs in a sport-specific setting, it is necessary to validate sport-specific movements. The aim of this study was to assess the concurrent validity of the Xsens IMU system by comparing it to the Vicon optoelectronic motion system for lower-limb joint angle measurements during jump-landing and change-of-direction tasks. Ten recreational athletes performed four tasks; single-leg hop and landing, running double-leg vertical jump landing, single-leg deceleration and push off, and sidestep cut, while kinematics were recorded by 17 IMUs (Xsens Technologies B.V.) and eight motion capture cameras (Vicon Motion Systems, Ltd). Validity of lower-body joint kinematics was assessed using measures of agreement (cross-correlation: XCORR) and error (root mean square deviation and amplitude difference). Excellent agreement was found in the sagittal plane for all joints and tasks (XCORR > 0.92). Highly variable agreement was found for knee and ankle in transverse and frontal plane. Relatively high error rates were found in all joints. In conclusion, this study shows that the Xsens IMU system provides highly comparable waveforms of sagittal lower-body joint kinematics in sport-specific movements. Caution is advised interpreting frontal and transverse plane kinematics as between-system agreement highly varied.

Background: A limited number of patients return to sport (RTS) after an anterior cruciate ligament reconstruction (ACLR) and patients who RTS have a relatively high risk for second ACL injury. The purpose of the current study was to compare the results of a test battery between patients who returned to the pre-injury level of sport (RTS group) and patients who did not (NO-RTS group).It was hypothesized that the RTS group showed better test results.Methods: Sixty-four patients (age 27.8 +/- 8.8 years) were included. The results of a multicomponent test battery (jump-landing task assessed with the Landing Error Scoring System (LESS), three hop tests, isokinetic strength test for quadriceps and hamstring) were compared between groups with a 2 x 2 ANOVA.Results: The RTS group showed a significantly lower LESS score (p = 0.010), significantly higher absolute scores on hop tests with both legs (injured leg: single leg hop test p = 0.013, triple leg hop test p = 0.024, side hop test p = 0.021: non-injured leg: single leg hop test p 0.011, triple leg hop test p = 0.023, side hop test p = 0.032) and significantly greater hamstring strength in the injured leg (p = 0.009 at 60 degrees/s, p = 0.012 at 180 degrees/s and p - 0.013 at 300 degrees/s). No differences in test results were identified between patients who sustained a second ACL injury and patients who did not.Conclusion: Patients after ACLR with better jump-landing patterns, hop performance and greater hamstring strength have greater likelihood for RTS. However, our findings show that RTS criteria fail to identify patients who are at risk for a second ACL injury. (C) 2020 The Author(s). Published by Elsevier B.V.

Background Single-leg hop tests are commonly performed in the forward direction to evaluate functional performance. However, athletes move in multiple directions during pivoting sports. The first aim of this study was to examine test–retest reliability of single-leg hop tests in the forward, medial and rotational direction in non-injured athletes. Second, the discriminative ability to detect leg asymmetries with these hop tests in anterior cruciate ligament (ACL) reconstructed athletes was determined. Methods Sixteen recreational non-injured participants (eight females, eight males; 22.4 ± 1.9 years) were tested twice (one-week interval) and performed the single hop for distance (SH), triple hop for distance (TH), medial side triple hop for distance (MSTH) and 90° medial rotation hop for distance (MRH). Intraclass correlation coefficients (ICCs), standard errors of measurement (SEM) and smallest detectable differences (SDD) were calculated. Discriminative ability was determined in 32 ACL-reconstructed participants (four females, 28 males; 24.4 ± 4.6 years; six months postoperative) who performed the same hop tests once. Results The ICCs ranged between 0.93 and 0.98. The SEM and SDD were respectively 2.6–4.1% and 7.2–11.3% of the mean hop distance of the group. The proportion (%) of ACL-reconstructed participants passing the ≥ 90% limb symmetry cut-off was 62.5 (SH), 59.4 (TH), 40.6 (MSTH) and 46.9 (MRH). Conclusion Excellent test–retest reliability of forward, medial and rotational hop tests was found. This allows clinicians to make informed interpretations of changes in hop test distances when retesting athletes. Medial and rotational hop tests are more likely to show limb asymmetries in ACL-reconstructed participants compared to forward hop tests.

Background : The goal of a rehabilitation programme after anterior cruciate ligament (ACL) reconstruction is to manage a patient's goals and expectations (i.e., returning to physical activities and sports) while minimizing the risk of new injury, particularly a new ACL injury. Although general rehabilitation programmes have been proposed, some factors can lead to adapting each programme to each patient. Objective : To describe how different variables, including surgical techniques, sports participation, psycho-social and contextual factors can modify the rehabilitation programme. Methods : We performed a narrative review with input from experts in the field (level of evidence 5). Conclusions : Modifying factors of the ACL rehabilitation programme are related to the initial lesion or surgery, to sports, or to psychological or social aspects. Regarding the type of graft, the rehabilitation is mainly different in the early postoperative phase; the other phases are not graft-based but rather goal-based rehabilitation. Depending on the meniscal or cartilage repair, the rehabilitation protocol will initially take priority over the anterior cruciate ligament reconstruction protocol. The ACL reconstruction rehabilitation programme should meet the requirements of the anticipated sports, to optimize the athlete's ability to return to the expected level and minimize the risk of reinjury. Psycho-social and contextual factors must also be considered in rehabilitation care to individualize and optimize each patient's programme.

Introduction Le manque de preparation physique, la charge d’entrainement ou la fatigue pourraient avoir un impact sur le nombre de blessures sportives observees au cours de la saison sportive. Le but de cette etude etait d’analyser la repartition des lesions du ligament croise anterieur (LCA) au cours de la saison dans les sports a pivot chez des non-professionnels. L’hypothese etait que la repartition n’etait pas uniforme au cours de la saison. Materiel et methodes Mille un lesions du LCA extraites d’un registre intrahospitalier et survenues entre 2011 et 2017, ont ete analysees. Sept cent cinquante-six representaient des blessures sportives dont 386 survenues dans un sport a pivot (football : 275, basket-ball : 56, handball : 55). La distribution des lesions au cours de l’annee a ete divisee en 6 segments de 2 mois. Le segment 1 (S1) representait les deux premiers mois de reprise sportive. Pour le football, S1 correspondait aux mois de septembre/octobre (lesions analysees de septembre 2011 a aout 2017) et pour le basket-ball/handball aux mois d’octobre/novembre (lesions analysees d’octobre 2011 a septembre 2017). Des tests de Chi2 ont permis de determiner si la repartition des lesions differait entre hommes et femmes, categories d’âge (> 21, 21–35, > 35), sports (football, basket-ball, handball) et mecanismes de lesion (contact, non-contact). Le seuil de signification etait place a p > 0,05. Resultats La distribution des lesions etait : S1 : 28 %–106, S2 : 13 %–52, S3 : 12 %–48, S4 : 17 %–66 ; S5 : 15 %–57 ; S6 : 15 %–57. Aucune difference n’a pu etre identifiee entre categories d’âge (> 21 : 111, 21–35 : 231, > 35 : 44) ou mecanismes de lesion (contact : 123, non contact : 263). La repartition des lesions variait toutefois entre hommes et femmes (p > 0,05) et selon le sport (p > 0,01). L’observation a ete confirmee pour le football (S1 : 27 %–73, S2 : 10 %–28, S3 : 10 %–27, S4 : 18 %–49, S5 : 20 %–56, S6 : 15 %–42, p > 0,01) et le basket-ball (S1 : 32 %–18, S2 : 21 %–12, S3 : 20 %–11, S4 : 11 %–6, S5 : 2 %–1, S6 : 14 %–8, p > 0,01). Discussion La prevalence des lesions du LCA varie au cours d’une saison sportive confirmant ainsi notre hypothese. Elle etait plus elevee en S1 dans le football et le basket-ball. Ceci pourrait etre explique par un manque de preparation physique et une augmentation de la charge physique apres la pause estivale. Conclusion Les resultats bases sur notre registre intra-hospitalier suggerent que les lesions du LCA survenues dans la pratique d’un sport a pivot sont particulierement elevees en debut de saison chez des sportifs non-professionnels. D’autres etudes sont necessaires pour confirmer ces resultats et determiner si une meilleure preparation physique et une augmentation progressive de la charge d’entrainement pourrait beneficier aux athletes.

Zusammenfassung Die Pravention von Verletzungen erlangt immer grosere Bedeutung. Voraussetzung ist das Verstandnis der Risikofaktoren und Verletzungsmechanismen. Praventionsstrategien beabsichtigen die Modifikation intrinsischer und extrinsischer Faktoren. Extrinsische Faktoren, d.h. ausere Rahmenbedingungen oder Regelwerk lassen sich nur sehr bedingt modifizieren und eine Effektivitat ist kaum belegt. Intrinsische Faktoren zielen v.a. ab auf die Umstellung problematischer Bewegungsablaufe durch Praventionsprogramme. Es liegt moderate Evidenz vor, dass Praventionsprogramme auf Basis neuromuskularen Trainings die Verletzungsgefahr reduzieren konnen. Wirksamste Komponente ist Plyometrietraining hoher Intensitat. Eine Integration von Praventionsprogrammen ins Training wird empfohlen.

Hop tests are frequently used to determine return to sports (RTS) after anterior cruciate ligament reconstruction (ACLR). Given that bilateral deficits are present after ACLR, this may result in a falsely high limb symmetry index (LSI), since LSI is calculated as a ratio between the values of the limbs.HypothesisAthletes after ACLR would achieve LSI > 90% for the hop test. Secondly, athletes after ACLR demonstrate decreased jump distance on the single hop for distance (SLH) and triple leg hop for distance (TLH) and decreased number of hops for the side hop (SH) for both involved and uninvolved limbs compared to normative data of sex, age and type of sports matched healthy athletes.Materials and MethodsFifty-two patients (38 males mean age 23.9 ±3.5 yrs; 14 females mean age 21.7±3.5 years) who had undergone an ACLR participated in this study. Patients performed the 3 hop tests at a mean time of 7.0 months after ACLR. Hop distance, number of side hops and LSI were compared with normative data of 188 healthy athletes.ResultsThe differences between the involved limb and the uninvolved limb were significant in all hop tests (SLH p=0.003, TLH p=0.003 , SH p=0.018). For females, only significant between limb differences were found in the SLH (p=0.049). For both the SLH and the TLH, significant differences were found between the involved limb and the normative data (males; SLH p