Extrinsic Risk Factors for Primary Noncontact Anterior Cruciate Ligament Injury in Adolescents Aged between 14 and 18 years: A Systematic Review.

BACKGROUND: Adolescents present a high incidence of ACL injury compared with other age groups. Examining the risk factors that predispose adolescents to primary noncontact ACL injury is a key strategy to decrease the number of injuries in this population. OBJECTIVE: The aim of this systematic review was to summarise the existing literature investigating extrinsic risk factors that have been linked with primary noncontact ACL injury risk (identified either using ACL injury occurrence or using screening tests measuring biomechanical mechanisms for noncontact ACL injury) in adolescents including research investigating: (1) the association between extrinsic risk factors and primary noncontact ACL injury risk; and (2) whether primary noncontact ACL injury risk was different in populations or groups exposed to different extrinsic risk factors in adolescents. METHODS: The same search strategy was used in MEDLINE, SPORTDiscus, CINAHL, PubMed and Embase. Articles were included if: written in English; published in peer-reviewed journals; investigating and discussing primary noncontact ACL injury risk associated with extrinsic risk factors; they were original research articles with an observational design; and participants presented a mean age ranging between 14 and 18 years. The Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies (QATOCCS) was used to assess the quality and risk of bias of the articles included in this systematic review. RESULTS: The systematic review included 16 eligible articles published up to August 2022 about extrinsic risk factors for primary noncontact ACL injury including: sport (8 studies); sport exposure amount (5); sport level (3); sport season (1); environment (2); equipment (1). Differences in biomechanical risk factors predisposing to ACL injury were reported by sport in female adolescents playing basketball and soccer; however, no good evidence of differences in primary noncontact ACL injury rate by sport was reported in both male and female adolescents. There was contrasting evidence about associations between sport exposure and biomechanical and neuromuscular risk factors predisposing to ACL injury or primary noncontact ACL injury rate in both male and female adolescent players from different sports. There was weak evidence of differences in biomechanical risk factors predisposing to ACL injury by environmental condition in both male and female adolescents playing soccer and season phase in male adolescents playing basketball. Lastly, few good-quality articles suggested that higher sport level might be associated with increased primary noncontact ACL injury rate in female adolescents playing basketball and floorball and that bracing might not prevent primary noncontact ACL injuries in both male and female adolescent players from different sports. DISCUSSION: The findings emphasise the need for further research to clarify the evidence about extrinsic risk factors and primary noncontact ACL injury in adolescents to develop ACL injury prevention guidelines that would help practitioners and researchers identify adolescents at risk and design future interventions. Future epidemiological studies should collect data about extrinsic factors as well as data about primary noncontact injury separately from secondary injuries or contact injuries to better inform primary noncontact ACL injury prevention in adolescents. REGISTRATION: https://doi.org/10.17605/OSF.IO/VM82F (11/08/2021).

Educator-Perceived Barriers and Facilitators to Structured-Physical Activity in Early Childhood Centres: A Systematic Review.

Purpose: Physical activity (PA) and motor competence development are vital for young children, yet many early childhood education and care (ECEC) centers struggle to successfully implement PA programs, particularly those organized and led by educators. This review aimed to synthesize qualitative literature to (1) identify educator-perceived barriers and facilitators to structured-PA in ECEC centers, and (2) map these to the COM-B model and Theoretical Domains Framework (TDF). Methods: Following PRISMA guidelines, a systematic search of five databases was conducted in April 2021 and updated in August 2022. Records were screened in Covidence software using predefined eligibility criteria. Using the framework synthesis method, data extraction and synthesis were conducted in coding forms in Excel and NVivo. Results: Of 2382 records identified, 35 studies were included, representing 2,365 educators across 268 ECEC centers in 10 countries. Using the COM-B model and TDF, an evidence-informed framework was developed. Findings revealed the greatest barriers concerned educator "opportunity" (e.g. competing time and priorities, policy tensions, indoor/outdoor space constraints) and "capability" (e.g. lack of PA knowledge and practical, hands-on skills) to implement structured-PA. Although fewer studies reported factors that influenced educator "motivation", several themes intersected across the three COM-B components illustrating the complexity of behavioral determinants in this setting. Conclusions: Interventions grounded in theory that utilize a systems approach to target multiple levels of influence on educator behavior, and are flexible and adaptable locally, are recommended. Future work should seek to address societal barriers, structural challenges in the sector, and the PA educational needs of educators. PROSPERO Registration: CRD42021247977.

Identifying modifiable risk factors and screening strategies associated with anterior cruciate ligament injury risk in children aged 6 to 13 years: A systematic review.

Growing anterior cruciate ligament (ACL) injury incidence is reported in countries across Europe, North America and in Australia for 5-14-year-olds, yet research on injury risk reduction predominantly focuses on populations aged > 13 years. For injury risk reduction, it is crucial to understand (i) which modifiable risk factors are associated with ACL injury in children (6-13 years) and (ii) how these risk factors are assessed. Articles were grouped according to sex/gender and/or maturational/age differences and examined modifiable risk factors during different physical screening tasks. The included articles (n = 40) predominantly examined intrinsic risk factors in girls aged 10-13 years. Factors mechanically linked to increased ACL loading at this age included increased peak knee adductor moments, knee valgus angles, hip and knee extension, and ground reaction forces. Assessment focused on laboratory-based assessments (e.g., motion capture, force plates). This review concluded that modifiable risk factors are present in children aged 6-13 years and that injury risk reduction strategies should be implemented as early as possible regardless of sex/gender. Further, screening strategies need updating to be childhood specific and feasible for the wide community. Additional research on extrinsic risk factors, norm values and children aged 6-9 years could allow for more targeted risk reduction strategies.

Increasing rates of ACL injuries in children aged 5 to 14 years are reported in countries across Europe, North America and in AustraliaResearch on modifiable risk factors focuses on internal risk factors in children aged 10-13 years and neglects external risk factors as well as younger children (6-10 years)Screening strategies to determine risk of ACL injury risk in children are laboratory based as opposed to cost-effective and quicker-to-analyse in-field assessmentResearch is warranted to examine external risk factors and in-field screening strategies in childhood.

Training interventions to reduce the risk of injury to the lower extremity joints during landing movements in adult athletes: a systematic review and meta-analysis.

Objective: Aim of this systematic review was to summarise training interventions designed to reduce biomechanical risk factors associated with increased risk of lower extremity landing injuries and to evaluate their practical implications in amateur sports. Design: Systematic review and meta-analysis. Data sources: MEDLINE, Scopus and SPORTDiscus. Eligibility criteria: Training intervention(s) aimed at reducing biomechanical risk factors and/or injury rates included the following: (1) prospective or (non-)randomised controlled study design; (2) risk factors that were measured with valid two-dimensional or three-dimensional motion analysis systems or Landing Error Scoring System during jump landings. In addition, meta-analyses were performed, and the risk of bias was assessed. Results: Thirty-one studies met all inclusion criteria, capturing 11 different training interventions (eg, feedback and plyometrics) and 974 participants. A significantly medium effect of technique training (both instruction and feedback) and dynamic strengthening (ie, plyometrics with/without strengthening) on knee flexion angle (g=0.77; 95% CI 0.33 to 1.21) was shown. Only one-third of the studies had training interventions that required minimal training setup and additional coaching educations. Conclusion: This systematic review highlights that amateur coaches can decrease relevant biomechanical risk factors by means of minimal training setup, for example, instructing to focus on a soft landing, even within only one training session of simple technique training. The meta-analysis emphasises implementing technique training as stand-alone or combined with dynamic strengthening into amateur sport training routine.

What is needed to reduce the risk of anterior cruciate ligament injuries in children? - Hearing from experts.

OBJECTIVE: Anterior cruciate ligament (ACL) injuries are an emerging health problem in children. Acknowledging considerable gaps in knowledge, the aim of this study was to examine the current knowledge on childhood ACL injury, and to explore risk assessment and reduction strategies, with experts in the research community. DESIGN: Qualitative study; semi-structured expert interviews. METHODS: Interviews with seven international, multidisciplinary academic experts were conducted from February until June 2022. A thematic analysis approach organized verbatim quotes into themes using Nvivo Software. RESULTS: Gaps in knowledge on the actual injury mechanism, and influence of physical activity behaviours, constrain targeted risk assessment and reduction strategies in childhood ACL injuries. Strategies to examine and reduce the risk of ACL injury included: examining an athletes' whole-body performance, moving from constraint (e.g., squat) to less constraint (e.g., single-leg) tasks, making assessments into children's context, building a movement repertoire at young age, performing risk reduction programs, multiple sports, and prioritising rest. CONCLUSION: Research is urgently warranted on the actual injury mechanism, reasons for ACL injuries in children, and potential risk factors to update risk assessment and reduction strategies. Further, educating stakeholders on risk reduction strategies could be essential to address the increasing occurrence of childhood ACL injuries.