Background: Deficits in dynamic neuromuscular control have been associated with post-injury sequelae and increased injury risk. The Y-Balance Test Lower Quarter (YBT-LQ) has emerged as a tool to identify these deficits. Purpose: To review the reliability of the YBT-LQ, determine if performance on the YBT-LQ varies among populations (i.e., sex, sport/activity, and competition level), and to determine the injury risk identification validity of the YBT-LQ based on asymmetry, individual reach direction performance, or composite score. Study Design: Systematic Review Methods: A comprehensive search was performed of 10 online databases from inception to October 30, 2019. Only studies that tested dynamic single leg balance using the YBT-LQ were included. Studies were excluded if the Y-Balance Test kit was not utilized during testing or if there was a major deviation from the Y-Balance test procedure. For methodological quality assessment, the modified Downs and Black scale and the Newcastle-Ottawa Scale were used. Results: Fifty-seven studies (four in multiple categories) were included with nine studies assessing reliability, 36 assessing population differences, and 16 assessing injury prediction were included. Intra-rater reliability ranged from 0.85-0.91. Sex differences were observed in the posteromedial direction (males: 109.6 [95%CI 107.4-111.8]; females: 102.3 [95%CI 97.2-107.4; p = 0.01]) and posterolateral direction (males: 107.0 [95%CI 105.0-109.1]; females: 102.0 [95%CI 97.8-106.2]). However, no difference was observed between sexes in the anterior reach direction (males: 71.9 [95%CI 69.5-74.5]; females: 70.8 [95%CI 65.7-75.9]; p=0.708). Differences in composite score were noted between soccer (97.6; 95%CI 95.9-99.3) and basketball (92.8; 95%CI 90.4-95.3; p <0.01), and baseball (97.4; 95%CI 94.6-100.2) and basketball (92.8; 95%CI 90.4-95.3; p=0.02). Given the heterogeneity of injury prediction studies, a meta-analysis of these data was not possible. Three of the 13 studies reported a relationship between anterior reach asymmetry reach and injury risk, three of 10 studies for posteromedial and posterolateral reach asymmetry, and one of 13 studies reported relationship with composite reach asymmetry. Conclusions: There was moderate to high quality evidence demonstrating that the YBT-LQ is a reliable dynamic neuromuscular control test. Significant differences in sex and sport were observed. If general cut points (i.e., not population specific) are used, the YBT-LQ may not be predictive of injury. Clinical population specific requirements (e.g., age, sex, sport/activity) should be considered when interpreting YBT-LQ performance, particularly when used to identify risk factors for injury. Level of Evidence: 1b

The goal of the OPTIKNEE consensus is to improve knee and overall health, to prevent osteoarthritis (OA) after a traumatic knee injury. The consensus followed a seven-step hybrid process. Expert groups conducted 7 systematic reviews to synthesise the current evidence and inform recommendations on the burden of knee injuries; risk factors for post-traumatic knee OA; rehabilitation to prevent post-traumatic knee OA; and patient-reported outcomes, muscle function and functional performance tests to monitor people at risk of post-traumatic knee OA. Draft consensus definitions, and clinical and research recommendations were generated, iteratively refined, and discussed at 6, tri-weekly, 2-hour videoconferencing meetings. After each meeting, items were finalised before the expert group (n=36) rated the level of appropriateness for each using a 9-point Likert scale, and recorded dissenting viewpoints through an anonymous online survey. Seven definitions, and 8 clinical recommendations (who to target, what to target and when, rehabilitation approach and interventions, what outcomes to monitor and how) and 6 research recommendations (research priorities, study design considerations, what outcomes to monitor and how) were voted on. All definitions and recommendations were rated appropriate (median appropriateness scores of 7–9) except for two subcomponents of one clinical recommendation, which were rated uncertain (median appropriateness score of 4.5–5.5). Varying levels of evidence supported each recommendation. Clinicians, patients, researchers and other stakeholders may use the definitions and recommendations to advocate for, guide, develop, test and implement person-centred evidence-based rehabilitation programmes following traumatic knee injury, and facilitate data synthesis to reduce the burden of knee post-traumatic knee OA.

Objective: To determine sex-based differences in risk of a second ACL injury (overall and by laterality) following primary ACL reconstruction in athletes who are attempting to return to sport.Design: Systematic review with meta-analysis.Data sources: Systematic search of five databases conducted in August 2019.Eligibility criteria for selecting studies: Studies reporting sex-based differences in the incidence of second ACL injury in athletes attempting to return-to-sports and who were followed for at least 1 year following primary ACL reconstruction.Results: Nineteen studies were included in this review, with seven studies excluded from the primary meta-analysis due to high risk of bias. The remaining 12 studies (n=1431 females, n=1513 males) underwent meta-analysis, with all 19 studies included in a sensitivity analysis. Total second ACL injury risk was 21.9% (females: 22.8%, males: 20.3%). Females were found to have 10.7% risk of an ipsilateral ACL injury and 11.8% risk of a contralateral ACL injury. Males were found to have 12.0% risk of an ipsilateral ACL injury and 8.7% risk of a contralateral ACL injury. No statistically significant differences were observed for total second ACL injury risk (risk difference=−0.6%, 95% CI −4.9 to 3.7, p=0.783, I²=41%) or contralateral ACL injury risk (risk difference=1.9%, 95% CI −0.5% to 4.4%, p=0.113, I²=15%) between sexes. Females were found to have a 3.4% absolute risk reduction in subsequent ipsilateral ACL injury risk compared with males (risk difference=−3.4%, 95% CI −6.7% to −0.02%, p=0.037, I²=35%).Conclusion: Both sexes have >20% increased risk of experiencing a second ACL injury. Any difference in the absolute risk of either a subsequent ipsilateral or contralateral ACL injury between sexes appears to be small.Registration: PROSPERO (CRD42020148369)