Molecular biomarker approaches to prevention of post-traumatic osteoarthritis.

Up to 50% of individuals develop post-traumatic osteoarthritis (PTOA) within 10 years following knee-joint injuries such as anterior cruciate ligament rupture or acute meniscal tear. Lower-extremity PTOA prevalence is estimated to account for ≥12% of all symptomatic osteoarthritis (OA), or approximately 5.6 million cases in the USA. With knowledge of the inciting event, it might be possible to 'catch PTOA in the act' with sensitive imaging and soluble biomarkers and thereby prevent OA sequelae by early intervention. Existing biomarker data in the joint-injury literature can provide insights into the pathogenesis and early risk trajectory related to PTOA and can help to elucidate a research agenda for preventing or slowing the onset of PTOA. Non-traumatic OA and PTOA have many clinical, radiological and genetic similarities, and efforts to understand early risk trajectories in PTOA might therefore contribute to the identification and classification of early non-traumatic OA, which is the most prevalent form of OA.

An 8-week injury prevention exercise program combined with change-of-direction technique training limits movement patterns associated with anterior cruciate ligament injury risk.

Knee ligament sprains are common during change-of-direction (COD) maneuvers in multidirectional team sports. This study aimed to compare the effects of an 8-week injury prevention exercise program containing COD-specific exercises and a similar program containing linear sprint exercises on injury- and performance-related variables during a 135° COD task. We hypothesized that the COD-specific training would lead to (H1) stronger reductions in biomechanical variables associated with anterior cruciate ligament (ACL) injury risk during COD, i.e. knee abduction moment and angle, hip internal rotation angle and lateral trunk lean, and (H2) more effective improvements in COD performance according to the COD completion time, executed angle, ground contact time, and approach speed. Twenty-two sports science students (40% female) completed biomechanical assessments of COD movement strategies before and after participating in two supervised 25-min training sessions per week over 8 weeks. We observed significant 'training x group' interaction effects in support of H1: the COD-specific training but not the linear sprint training led to reduced peak knee abduction moments (interaction, p = 0.027), initial knee abduction (interaction, p < 0.001), and initial lateral trunk lean angles (interaction, p < 0.001) compared to baseline. Although the COD-specific training resulted in sharper executed angles (interaction, p < 0.001), the sprint-specific training group showed reduced COD completion (interaction, p = 0.037) and ground contact times (interaction, p < 0.001). In conclusion, a combination of generic and COD-specific injury prevention training resulted in COD technique adaptations that can help to avoid ACL injury-prone COD movements but may negatively affect COD speed.

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.

The Effect of a Knee Brace on Muscle Forces during Single-Leg Landings at Two Heights.

Single-leg landing is one of the maneuvers that has been linked to non-contact anterior cruciate ligament (ACL) injuries, and wearing knee braces has been shown to reduce ACL injury incidence. The purpose of this study was to determine whether wearing a knee brace has an effect on muscle force during single-leg landings at two heights through musculoskeletal simulation. Eleven healthy male participants, some braced and some non-braced were recruited to perform single-leg landings at 30 cm and 45 cm. We recorded the trajectories and ground reaction forces (GRF) using an eight-camera motion capture system and a force platform. The captured data were imported into the generic musculoskeletal model (Gait2392) in OpenSim. Static optimization was used to calculate the muscle forces. The gluteus minimus, rectus femoris, vastus medialis, vastus lateralis, vastus medialis medial gastrocnemius, lateral gartrocnemius, and soleus muscle forces were all statistically significant different between the braced and non-braced participants. Simultaneously, increasing the landing height significantly affected the gluteus maximums, vastus medialis, and vastus intermedia muscle forces. Our findings imply that wearing a knee brace may alter muscle forces during single-leg landings, preventing ACL injuries. Additionally, research demonstrates that people should avoid landing from heights due to the increased risk of knee injuries.

Preventing Knee Injuries: Exercises to Keep You From Getting Sidelined.

Recently, injury prevention experts developed a guideline for rehabilitation clinicians to use to help you avoid getting another knee injury. Here, we explain what the guidelines say about which exercises you should do to stay injury-free, how often to do the exercises, and when to do the exercises. J Orthop Sports Phys Ther 2023;53(2):105. doi:10.2519/jospt.2023.0503.

Exercise-Based Interventions for Preventing Knee and Anterior Cruciate Ligament Injury: Using the Evidence to Guide Musculoskeletal Rehabilitation Practice.

Knee and anterior cruciate ligament (ACL) injuries are common and can be severe. Some knee injuries carry long-term implications for the health of active people, including a risk of osteoarthritis and physical inactivity. Preventing injuries from occurring is critical to helping people stay active and healthy through their life. Here we present for clinicians, the most up-to-date information to guide their work to prevent knee and ACL injuries. J Orthop Sports Phys Ther 2023;53(2):103-104. doi:10.2519/jospt.2023.0502.

Biomechanical Effects of Prophylactic Knee Bracing on Anterior Cruciate Ligament Injury Risk: A Systematic Review.

OBJECTIVE: Prophylactic knee braces (PKBs) are widely used by athletes in pivoting and landing sports and have the potential to influence knee movement and alignment, thus modulating anterior cruciate ligament (ACL) injury risk. This systematic review analyses current evidence on the biomechanical effects that PKBs have in the prevention of ACL injuries. DATA SOURCES: The review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Searches were conducted on PubMed, Web of Science, Scopus, Ovid MEDLINE, EMBASE, Cochrane, and CINAHL for studies published from inception until May 31, 2021. Included studies assessed the effects of PKBs on biomechanical variables associated with ACL injuries in landing or pivoting tasks, comparing between braced and unbraced conditions. MAIN RESULTS: A total of 234 articles were identified; from which, 14 controlled, laboratory, biomechanical studies were included in this review. The effects of PKBs on knee biomechanics could be divided into kinematic variables in the coronal, sagittal, and transverse planes; and common kinetic variables, such as ground reaction force (GRF) and ACL load/strain. Also, PKBs were found to have protective effects in coronal and transverse plane kinematics, but results in the sagittal plane were inconclusive. Assessing knee kinetics, PKBs were advantageous in decreasing ACL load/strain but had no significant effect on GRF. CONCLUSIONS: Prophylactic knee braces may serve to reduce ACL injury risk by modulating knee coronal and transverse plane movements and ACL load/strain during high-risk maneuvres. Precise recommendations are limited by study heterogeneity. More prospective studies are needed to assess ACL injury risk during high-risk sports using specific PKBs.

Predictive modeling of lower extremity injury risk in male elite youth soccer players using least absolute shrinkage and selection operator regression.

PURPOSE: To (1) identify neuromuscular and biomechanical injury risk factors in elite youth soccer players and (2) assess the predictive ability of a machine learning approach. MATERIAL AND METHODS: Fifty-six elite male youth soccer players (age: 17.2 ± 1.1 years; height: 179 ± 8 cm; mass: 70.4 ± 9.2 kg) performed a 3D motion analysis, postural control testing, and strength testing. Non-contact lower extremities injuries were documented throughout 10 months. A least absolute shrinkage and selection operator (LASSO) regression model was used to identify the most important injury predictors. Predictive performance of the LASSO model was determined in a leave-one-out (LOO) prediction competition. RESULTS: Twenty-three non-contact injuries were registered. The LASSO model identified concentric knee extensor peak torque, hip transversal plane moment in the single-leg drop landing task and center of pressure sway in the single-leg stance test as the three most important predictors for injury in that order. The LASSO model was able to predict injury outcomes with a likelihood of 58% and an area under the ROC curve of 0.63 (sensitivity = 35%; specificity = 79%). CONCLUSION: The three most important variables for predicting the injury outcome suggest the importance of neuromuscular and biomechanical performance measures in elite youth soccer. These preliminary results may have practical implications for future directions in injury risk screening and planning, as well as for the development of customized training programs to counteract intrinsic injury risk factors. However, the poor predictive performance of the final model confirms the challenge of predicting sports injuries, and the model must therefore be evaluated in larger samples.

Prevention of knee joint injuries in winter sports training / Prevenção de lesões articulares do joelho no treino dos esportes de inverno / Prevención de las lesiones articulares de la rodilla en el entrenamiento de los deportes de invierno

ABSTRACT Introduction: With the 2022 Winter Olympic Games launch, ice and snow sports have come into the spotlight, receiving government incentives to encourage their practice. Objective: Examine the causes of knee injury in skiers, proposing preventive measures for joint injury. Methods: The current situation of joint injury in skiers' knees, joint movement in skiing, the cause of joint injury, and the prevention of joint injury were analyzed, and scientific prevention and corresponding treatment plan were developed according to the results of the analysis. Results: The injury rate among skiers is high. Ligament injury, tendon injury, and muscle strain are the three main types of injury. There are 57 mild injuries of various types to the knee joint - 53.27% of all injuries; 41 moderate injuries, representing 38.32% of all injuries; 9 serious injuries, representing 8.41% of all injuries, with minor injuries. Conclusion: This article examines knee motion and the causes of knee injury in skiers and proposes preventive measures for joint injury. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

RESUMO Introdução: Com o lançamento dos Jogos Olímpicos de Inverno de 2022, os esportes de gelo e neve entraram em evidência, recebendo incentivos governamentais para encorajamento de sua prática. Objetivo: Examinar as causas da lesão no joelho em esquiadores, propondo medidas preventivas para a lesão articular. Métodos: Foram analisadas a situação atual de lesão articular nos joelhos dos esquiadores, o movimento articular no esqui, a causa das lesões articulares e a prevenção de lesões articulares, além de um plano de prevenção científica e tratamento correspondente, de acordo com os resultados da análise. Resultados: A taxa de lesões em esquiadores é alta. Lesão ligamentar, lesão tendinosa e tensão muscular são os três principais tipos de lesão. Há 57 lesões leves de vários tipos na articulação do joelho - 53,27% de todas as lesões; 41 lesões moderadas, representando 38,32% de todas as lesões; 9 lesões graves, representando 8,41% de todos os ferimentos, com ferimentos menores. Conclusão: Este artigo examina o movimento do joelho e as causas da lesão no joelho em esquiadores, e propõe medidas preventivas para lesão articular. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.

RESUMEN Introducción: Con la puesta en marcha de los Juegos Olímpicos de Invierno de 2022, los deportes de hielo y nieve han pasado a ser el centro de atención, recibiendo incentivos gubernamentales para fomentar su práctica. Objetivo: Examinar las causas de las lesiones de rodilla en los esquiadores, proponiendo medidas preventivas de las lesiones articulares. Métodos: Se analizó la situación actual de las lesiones articulares en las rodillas de los esquiadores, el movimiento articular en el esquí, la causa de las lesiones articulares y la prevención de las mismas, y se elaboró un plan científico de prevención y tratamiento correspondiente según los resultados del análisis. Resultados: El índice de lesiones en los esquiadores es alto. Las lesiones de ligamentos, las lesiones de tendones y las distensiones musculares son los tres tipos principales de lesiones. Hay 57 lesiones leves de diversos tipos en la articulación de la rodilla, el 53,27% de todas las lesiones; 41 lesiones moderadas, que representan el 38,32% de todas las lesiones; 9 lesiones graves, que representan el 8,41% de todas las lesiones, con lesiones leves. Conclusión: Este artículo examina el movimiento de la rodilla y las causas de las lesiones de rodilla en los esquiadores, y propone medidas preventivas para las lesiones articulares. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.

OPTIKNEE 2022: consensus recommendations to optimise knee health after traumatic knee injury to prevent osteoarthritis.

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.

Pediatric and Adolescent Knee Injuries: Risk Factors and Preventive Strategies.

It is estimated that approximately 2.5 million sports-related knee injuries occur in the pediatric population annually in the United States. Thus, identifying appropriate screening tools and injury prevention strategies is imperative. To develop successful injury prevention strategies, risk factor identification is the first step. There are two types of risk factors: non-modifiable (age, gender, injury history, and anatomical alignment) and modifiable risk factors (biomechanical and neuromuscular control, training loads, and body mass index). These risk factors can be addressed by three types of preventive interventions: primary, secondary, and tertiary. To translate study evidence to clinical practices and routine trainings, awareness of injury prevention and health promotion needs to be further strengthened.

Strategies to prevent and manage running-related knee injuries: a systematic review of randomised controlled trials.

OBJECTIVE: To evaluate the effectiveness of interventions to prevent and manage knee injuries in runners. DESIGN: Systematic review and meta-analysis. DATA SOURCES: MEDLINE, EMBASE, CINAHL, Web of Science and SPORTDiscus up to May 2022. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Randomised controlled trials (RCTs) with a primary aim of evaluating the effectiveness of intervention(s) to prevent or manage running-related knee injury. RESULTS: Thirty RCTs (18 prevention, 12 management) analysed multiple interventions in novice and recreational running populations. Low-certainty evidence (one trial, 320 participants) indicated that running technique retraining (to land softer) reduced the risk of knee injury compared with control treadmill running (risk ratio (RR) 0.32, 95% CI 0.16 to 0.63). Very low-certainty to low-certainty evidence from 17 other prevention trials (participant range: 24 -3287) indicated that various footwear options, multicomponent exercise therapy, graduated running programmes and online and in person injury prevention education programmes did not influence knee injury risk (RR range: 0.55-1.06). In runners with patellofemoral pain, very low-certainty to low-certainty evidence indicated that running technique retraining strategies, medial-wedged foot orthoses, multicomponent exercise therapy and osteopathic manipulation can reduce knee pain in the short-term (standardised mean difference range: -4.96 to -0.90). CONCLUSION: There is low-certainty evidence that running technique retraining to land softer may reduce knee injury risk by two-thirds. Very low-certainty to low-certainty evidence suggests that running-related patellofemoral pain may be effectively managed through a variety of active (eg, running technique retraining, multicomponent exercise therapy) and passive interventions (eg, foot orthoses, osteopathic manipulation). PROSPERO REGISTRATION NUMBER: CRD42020150630.

Injury Prevention Effect of MRI Imaging Technology in Physical Education and Sports Training.

In order to solve the problem of observing and analyzing the clinical value of MRI diagnosis in patients with knee sports injury and guiding clinical targeted treatment, the author proposed a sports injury prevention method in sports training teaching based on MRI image observation. This method retrospectively analyzed the imaging data of 101 patients with knee joint MRI examination due to osteoarthritis, sports injury and synovitis in joint surgery, and arthroscopic exclusion of true meniscus tear, MR multisequence and multiplane scans were performed to observe the anatomical features of TGL and MFL images and the occurrence rate of the lateral meniscus "false tear sign," and the χ 2 test was used to compare the occurrence rate of "pseudo-tear sign" between genders and sides. Experimental results show that the incidence of TGL on MRI was about 67.3% (68/101), and the incidence of "pseudo-tear sign" in the anterior horn of the lateral meniscus caused by TGL was 2.9% (2/68). The overall appearance rate of MFL on MRI was 91.1% (92/101), the appearance rate of plate anterior ligament (HL) was 13.9% (14/101), and the occurrence rate of "pseudo-tear sign" in the posterior horn of the lateral meniscus caused by HL was 7.1% (1/14). The occurrence rate of the posterior ligament (WL) was 77.2% (78/101), and the incidence of "pseudo-tear sign" in the posterior horn was 20.5% (16/78). According to the shape and course of TGL and MFL on MRI, and the direction and position of the lateral meniscus pseudotear, combined with MRI sagittal plane and coronal plane observation, it can effectively identify the true and false attributes of lateral meniscus anterior and posterior horn tears, thereby reducing unnecessary surgical treatment.

Reducing Knee Joint Load during a Golf Swing: The Effects of Ball Position Modification at Address.

As the modern golf swing has changed, the incidence of knee pain in professional golfers is increasing. For those with previous knee injuries, developing a golf-swing modification that reduces knee loading may be necessary to recover performance after injury. The purpose of this study was to test whether ball position modification reduces knee joint load in a golf swing. Thirteen male professional golfers participated in the study. Golf swings were captured using a three-dimensional motion capture system and two force platforms, with conditions for self-selected ball position and eight additional ball positions. Knee internal rotation and adduction moments were calculated. The length of one golf ball (4.27 cm) backward ball position (closer to the golfer) significantly reduced the peak internal rotation moment of the lead knee (- 13.8%) (p < 0.001) and the length of one golf ball (4.27 cm) away from the target ball position significantly reduced the peak adduction moment of the lead knee (- 11.5%) (p < 0.001) compared with that of the self-selected ball position. Based on these observations, we conclude that the backward ball position modification might be suggested for golfers with anterior cruciate ligament injuries, and the away from the target modification might be suggested for golfers with medial compartment knee osteoarthritis.

"Yeah, I Mean, You're Going to Handball, so You Want to Use Balls as Much as Possible at Training": End-Users' Perspectives of Injury Prevention Training for Youth Handball Players.

Young handball players experience high injury rates. Specific injury prevention programs reduce injury rates but are not well implemented into youth players' training. The 'Implementing injury Prevention training ROutines in TEams and Clubs in youth Team handball (I-PROTECT)' project addresses this challenge. The aim of this study was to investigate how youth handball coaches and players experienced the recently developed I-PROTECT GO pilot program, by focusing on barriers and facilitators. Three focus group interviews were conducted with coaches and players, and their answers were analyzed using a general inductive approach. The participants appreciated the program and found it useful for their context. The participants' statements about facilitators and barriers centered around the categories of resources, exercises, program design, and learning. Facilitators that emerged were motivating exercises (e.g., handball-specific), a helpful set-up (e.g., variation), having a clear purpose of exercises, the possibility to fulfil basic psychological needs while training, receiving instructions and feedback, and having role models. Barriers that emerged were limited space and material, difficulties with exercises, an unhelpful set-up (e.g., too repetitive), and undisciplined training. It is important to address perceived barriers and facilitators among coaches and players when developing injury prevention training programs to enhance the uptake of such training.

Editorial Commentary: Prevention of Complications During Multiple Ligament Knee Injury Reconstruction: It's Complicated!

Treatment of multiple-ligament knee injuries is complex and complicated. Surgeons should strive to keep their operative times under 5 hours, limit inside-out meniscal repair, consider fibular-based only posterolateral corner reconstructions (except in cases with associated proximal tibia-fibular joint injuries or massive posterolateral corner injuries), avoid acute surgery when possible, and proceed cautiously with ultra-low-velocity dislocations. Multiple-ligament knee injury reconstruction is challenging and complicated but a sincere thank you is extended to those surgeons who take on complex knee surgery.

Custom-Fitted Compression Garments Enhance Recovery From Muscle Damage in Rugby Players.

ABSTRACT: Brown, F, Jeffries, O, Gissane, C, Howatson, G, van Someren, K, Pedlar, C, Myers, T, and Hill, JA. Custom-fitted compression garments enhance recovery from muscle damage in rugby players. J Strength Cond Res 36(1): 212-219, 2022-to evaluate the effects of custom-fitted compression garments (CG) on recovery from muscle damage in rugby players. Forty-five players were tested for lower-body strength, power, and indices of muscle damage before completing a damaging protocol (20 × 20-m sprints with 5-m deceleration, 100 drop jumps). Players were randomly assigned to wear either custom-fitted (CF, n = 13), or standard-sized CG (SSG, n = 16), or to receive sham ultrasound therapy (CON, n = 16) immediately after exercise. Players were retested immediately, then after 24 and 48 hours. Strength recovery was significantly different between groups (F = 2.7, p = 0.02), with only CF recovering to baseline values by 48 hours (p = 0.973). Time × condition effects were also apparent for creatine kinase activity (χ2 = 30.4, p < 0.001) and midthigh girth (F = 3.7, p = 0.005), with faster recovery apparent in CF compared with both CON and SSG (p < 0.05). Custom-fitted CG improved strength recovery and indices of muscle damage in rugby players, compared with controls and standard-sized garments. Athletes and coaches would be advised to use appropriately fitted CG to enhance strength recovery after damaging exercise.

High compliance with the injury prevention exercise programme Knee Control is associated with a greater injury preventive effect in male, but not in female, youth floorball players.

PURPOSE: Evaluate team and player compliance with the Knee Control injury prevention exercise programme, study the association between player compliance and injury rates, and compare coach demographics, baseline prevention expectancies, and programme utilisation between teams with high and low compliance. METHODS: Prospective one-season cohort study based on a cluster randomised controlled trial on 301 (107 female) floorball players aged 12-17 years. Floorball exposure and injuries were self-reported weekly by players using the Oslo Sports Trauma Research Center questionnaire. Team and player compliance to Knee Control was reported monthly by coaches. Additionally, coaches answered pre- and post-season surveys. Teams were divided into a high (≥ 80%) or low (< 80%) compliance group based on their use of Knee Control during the season. Players were divided into three compliance groups based on their average weekly number of Knee Control sessions; high (≥ 2 sessions), intermediate (≥ 1 to < 2 sessions), and low dose (< 1 session). RESULTS: Mean team compliance for the high and low compliance groups were 95% (range 82-100) and 50% (range 13-66), respectively. Mean ± SD weekly Knee Control dose in the three player compliance groups were 2.4 ± 0.3, 1.4 ± 0.3, and 0.7 ± 0.3 sessions, respectively. There were no differences in total injury incidence between the player compliance groups, but players in the high-dose group had a 35% lower prevalence of injuries overall [adjusted prevalence rate ratio (PRR) 0.65, 95% CI 0.48-0.89] and 60% lower prevalence of substantial injuries (adjusted PRR 0.40, 95% CI 0.26-0.61) compared with the low-dose group. Male players in the high-dose group had consistently lower injury incidence and prevalence, while no between compliance group differences were seen in female players. There were no differences in sex, years of coaching experience, or baseline prevention expectancies in general between coaches for teams in the high vs. low compliance groups, but teams in the high compliance group had a better utilisation fidelity. CONCLUSION: There was a clear dose-response relationship between more frequent Knee Control use and lower injury rates in male floorball players, but not in female players. Teams with higher compliance also showed a better utilisation fidelity with the programme. LEVEL OF EVIDENCE: Level II.

Increased occurrence of ACL injuries for football players in teams changing coach and for players going to a higher division.

PURPOSE: To identify football-specific factors associated with ACL injuries that can be targeted for sport-specific injury prevention. METHODS: A study-specific questionnaire was developed to study the characteristics of ACL injuries in football including intrinsic, extrinsic, and injury specific factors. The questionnaire was available at the Swedish national knee ligament registry's website for the football players to voluntarily fill out. Data are presented on group level for all football players in total and for females and males separate to examine gender-specific differences. The results are based on answers collected over a 3-year period from 2875 football players, 1762 (61%) males and 1113 (39%) females. RESULTS: ACL were more frequently sustained during games 66% than during practices 25%. The injury mechanism was non-contact in 59% and contact in 41%. For the contact injuries during games, no action was taken by the referee in 63% of the situation and a red card was shown in 0.5%. The risk of ACL injury was highest early in the football game with 47% sustained during the first 30 min and 24% in the first 15 min. Players changing to a higher level of play 15% had a higher rate of ACL injuries than players changing to a lower level 8%. This difference was especially seen in female football players with 20% of ACL injuries being sustained by players going to a higher division compared to 7% for those going to a lower division. 15% of the male and 21% of the female ACL injuries occurred in teams with a coach change during the season. Knee control exercises to warm up was used by 31% of the female players and 16% of the males. 40% of the players reported that they did not plan on returning to football. CONCLUSION: Neuromuscular training programs have proven to reduce ACL injuries, but greater adherence to these remains a challenge as only 1 in 5 of the ACL-injured football players report using them. Teams changing coach and players going to a higher division appear to have an increased risk of ACL injury warranting attention and further investigations. LEVEL OF EVIDENCE: IV.