Programa preventivo de lesión de ligamento cruzado anterior en fútbol femenino durante períodos de confinamiento / Anterior Cruciate Ligament Injury Preventive Program for Soccer Female Players During Confinement Periods

Resumen La pandemia por COVID-19 obligó a paralizar el deporte en todo el mundo; por lo tanto, se redujo la carga de trabajo de los deportistas, lo cual, sumado al probable aumento de la densidad competitiva tras el período de confinamiento, resultará en un incremento del riesgo de lesión después del retorno a la competición. A este respecto, la rodilla es una de las zonas con mayor prevalencia de lesión en el fútbol femenino y la lesión del ligamento cruzado anterior (LCA) es de las más frecuentes y graves. En consecuencia, el objetivo del presente trabajo fue desarrollar un plan de prevención de lesión de LCA que pudiera ser llevado a cabo por mujeres futbolistas, durante períodos de confinamiento. Luego de una revisión de la literatura, se ha encontrado que el entrenamiento de fuerza (especialmente de la cadena posterior), el trabajo de la técnica de aterrizajes, así como el de estabilidad lumbopélvica y flexibilidad se asocian con un menor riesgo de lesión de LCA en mujeres. El programa se centra en factores de riesgo modificables, por lo que debe servir como una guía susceptible de adaptaciones, en función de cada contexto: las características individuales, el estado inicial y la evolución del sujeto durante su desarrollo. Por ende, en este estudio se plantea una intervención que pretende disminuir la probabilidad de lesión de LCA en mujeres futbolistas, tras el confinamiento, incidiendo, para ello, de forma directa sobre los mecanismos de lesión de LCA reportados en esta población.

Abstract The COVID-19 pandemic resulted in a worldwide sports shutdown, leading to a reduced athletes' workload, which is likely to increase the risk of injury after return to play when coupled with the expected increase in competitive density after the confinement period. In this regard, the knee is one of the joints with the highest injury prevalence among female soccer players, being the injury of the anterior cruciate ligament (ACL) one of the most frequent and severe. Thus, the present study aimed to develop an ACL injury prevention program that female soccer players could carry out during confinement periods. After reviewing the scientific literature, it was observed that strength training (with a main focus on the posterior chain), improved landing technique, lumbopelvic stability, and flexibility are associated with a lower risk of ACL injury in women. The program focuses on modifiable risk factors, so it should serve as a guide that can be adapted according to each context: individual characteristics, initial conditions, and evolution of the subject during development. Therefore, this study presents an intervention aiming at reducing the probability of ACL injury in female soccer players, after confinement periods, by directly influencing mechanisms of ACL injury previously reported for female soccer players.

Resumo A pandemia da COVID-19 forçou uma paralização mundial do esporte; portanto, a carga de trabalho dos atletas foi reduzida, o que, juntamente com o provável aumento da densidade competitiva após o período de confinamento, resultará em um risco maior de lesões após o retorno à competição. A esse respeito, o joelho é uma das áreas de lesão mais prevalecentes no futebol feminino e a lesão do ligamento cruzado anterior (LCA) é uma das mais frequentes e graves. Consequentemente, o objetivo do presente estudo é desenvolver um plano de prevenção de lesões do ACL que pode ser implementado por jogadoras de futebol feminino durante os períodos de internação. Após uma revisão da literatura, descobriu-se que o treinamento de força (especialmente da cadeia posterior), a técnica de aterrissagem, assim como o treinamento de estabilidade e flexibilidade lombo pélvica estão associados a um menor risco de lesão do LCA nas mulheres. O programa se concentra em fatores de risco modificáveis, portanto deve servir como um guia que possa ser adaptado de acordo com cada contexto: as características individuais, o estado inicial e a evolução da pessoa durante seu desenvolvimento. Portanto, este estudo propõe uma intervenção que visa reduzir a probabilidade de lesão do ACL em jogadoras de futebol feminino após o confinamento, afetando diretamente os mecanismos de lesão do ACL nelas relatados.

Most amateur football teams do not implement essential components of neuromuscular training to prevent anterior cruciate ligament injuries and lateral ankle sprains.

PURPOSE: Neuromuscular training (NMT) is effective at reducing football injuries. The purpose of this study was to document the use of NMT to prevent anterior cruciate ligament injuries and lateral ankle sprains in adult amateur football and to identify barriers for using NMT. METHODS: A preseason and in-season online survey was completed by players and coaches of 164 football teams. The survey contained questions concerning injury history, type and frequency of NMT, and barriers when NMT was not used. RESULTS: A total of 2013 players (40% female) and 180 coaches (10% female) completed the preseason survey, whereas 1253 players and 140 coaches completed the in-season survey. Thirty-four percent (preseason) to 21% (in-season) of players used NMT, but only 8% (preseason) to 5% (in-season) performed adequate NMT (i.e. both balance and plyometric exercises, at least twice per week). In the subpopulation of players with an injury history, 12% (preseason) and 7% (in-season) performed adequate NMT. With respect to the coaches, only 5% (preseason) and 2% (in-season) implemented adequate NMT. Most important barriers for using NMT for both players and coaches were a lack of belief in its effectiveness, a lack of knowledge, the belief that stretching is sufficient, and not feeling the need for it. CONCLUSION: Most amateur football teams do not implement essential components of NMT. The results highlight the urgent need for developing strategies to enhance the adequate use of NMT in amateur football. LEVEL OF EVIDENCE: 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.

Efficacy of Prophylactic Knee Bracing in Sports.

Anterior cruciate ligament (ACL) and medial collateral ligament (MCL) injuries are common knee injuries, which can result from contact and noncontact during sports, recreation, or work-related activities. Prophylactic knee braces (PKBs) have been designed to protect the knee and decrease risk of recurrence of these injuries. Despite their success, PKBs have not been proven to be consistently effective and cost of the device must be evaluated to optimize its use in sports, particularly American football. Biomechanical studies have suggested that increased hip and knee flexion angles may reduce frontal plane loading with bracing which can protect the knee joint. This is essential with knee loading and rotational moments because they are associated with jumping, landing, and pivoting movements. The clinical efficacy of wearing PKBs can have an impact on athletic performance with respect to speed, power, motion, and agility, and these limitations are evident in athletes who are unaccustomed to wearing a PKB. Despite these concerns, use of PKBs increases in patients who have sustained an MCL injury or recovering from an ACL reconstruction surgery. As the evidence continues to evolve in sports medicine, there is limited definitive data to determine their beneficial or detrimental effects on overall injury risk of athletes, therefore leading those recommendations and decisions for their usage in the hands of the athletic trainers and team physicians' experience to determine the specific brace design, brand, fit, and situations for use.

Lesiones del ligamento cruzado anterior en esquiadores: conceptos actuales / Anterior cruciate ligament injuries in skiers: current concepts

El esquí es un deporte individual con una tasa de lesiones de 1,84 por 1.000 días esquiador en la población general. Las roturas del ligamento cruzado anterior (LCA) son algunas de las más comunes, llegando a una tasa de 5 por cada 100 esquiadores por temporada a nivel competitivo, debido a la gran exigencia a la que se encuentran sometidas las rodillas. Lo anterior presenta un desafío para el traumatólogo a la hora de plantear un manejo. Se realizó una revisión de la literatura respecto de los mecanismos de lesión, tratamiento, prevención, rehabilitación y uso de órtesis en el retorno deportivo. Se describen los mecanismos clásicos de lesión en esquiadores amateurs y competitivos. La mayoría de las lesiones de LCA son de resolución quirúrgica, en que la recomendación de reconstrucción debe ser con injerto autólogo de hueso-tendón patelar-hueso, salvo en los pacientes mayores o en pacientes con fisis abierta, en los que se recomienda el uso de injerto autólogo de semitendinoso-gracilis. La prevención y rehabilitación se basan en mejorar la fuerza y el control neuromuscular de los estabilizadores dinámicos de la rodilla implementándose programas específicos, evaluación del gesto deportivo, y pruebas de control neuromuscular. Se recomienda el uso de órtesis funcionales adecuadas en los pacientes sometidos a reconstrucción del LCA. Las lesiones de LCA en esquiadores de nivel competitivo son habituales, de manejo específico y multidisciplinario. La elección del injerto y del tipo de rehabilitación son fundamentales en el retorno deportivo del esquiador. NIVEL DE EVIDENCIA: V.

Skiing is an individual sport with an injury rate of 1.84 per 1,000 skier days among the general population. Anterior cruciate ligament (ACL) tears are among the most common injuries in skiers, with a rate of 5 per 100 skiers per season at a competitive level, because of the great demand placed on the knees. Their treatment is a challenge for orthopedic surgeons. A review of the literature was carried out regarding injury mechanisms, treatment, prevention, rehabilitation, and the use of bracing in the return to sports. The classic injury mechanisms in amateur and competitive skiers are described. Most ACL injuries require surgical resolution, with reconstruction using autologous bone-patellar tendon-bone graft, except in older patients or those with open physis, who must receive an autologous semitendinosusgracilis graft. Prevention and rehabilitation are based on improving strength and neuromuscular control of the dynamic knee stabilizers, implementing specific programs, evaluating the sport movements, and performing neuromuscular control tests. Suitable functional bracings are recommended in patients undergoing ACL reconstruction. ACL injuries in competitive-level skiers are common, and their management is specific and multidisciplinary. The choice of graft and rehabilitation type is critical to resume skiing. LEVEL OF EVIDENCE: V.

Use of double leg injury screening to assess single leg biomechanical risk variables.

OBJECTIVES: The purpose of this article was to determine if differences in kinematic and kinetic variables observed in a double-leg screen carried over to a single-leg task. DESIGN: We used a case-control design with grouping based on performance during a double-leg jump landing. SETTING: All participants were selected from a large university setting and testing was performed in a biomechanics laboratory. PARTICIPANTS: Participants were females between 18 and 25 years of age with at least high school varsity experience in one or more of the following sports: soccer, lacrosse, field hockey, rugby, basketball, or team handball. MAIN OUTCOME MEASURES: Primary outcome measures were knee angles in the frontal and sagittal planes as well as vertical ground reaction force (vGRF). RESULTS: There were significant between group differences in peak knee flexion and knee flexion displacement during both the double and single-leg tasks, however between group differences for peak knee valgus and knee valgus displacement noted in the double-leg task were not observed in the single-leg task. vGRF was significantly different in the single-leg task but not the double-leg task. CONCLUSION: A double leg screening may not provide complete identification of risk of injury during sports requiring single leg tasks.

[Preventing anterior cruciate ligament injury in children is effective]. / Preventie van voorste-kruisbandletsels bij kinderen.

An anterior cruciate ligament (ACL) injury in children is a devastating injury. After an ACL injury 1 in 3 children obtain a second injury of the ipsilateral or contralateral ACL. Children who suffer an ACL injury also have a ten times higher risk of osteoarthritis. Preventative training programmes can decrease the risk of acute knee injuries in young sportspeople; however, implementation of these prevention programmes is challenging, so it is important to inform associations, clubs, youth trainers and parents about the added value of these programmes. Children with ACL injuries must receive specialized guidance during rehabilitation, regardless of whether they have been treated conservatively or surgically. Because of the risk of a second ACL injury,we recommend that children should not to return to pivoting sports until at least 12 months after surgery for ACL.

Real-time biofeedback integrated into neuromuscular training reduces high-risk knee biomechanics and increases functional brain connectivity: A preliminary longitudinal investigation.

Prospective evidence indicates that functional biomechanics and brain connectivity may predispose an athlete to an anterior cruciate ligament injury, revealing novel neural linkages for targeted neuromuscular training interventions. The purpose of this study was to determine the efficacy of a real-time biofeedback system for altering knee biomechanics and brain functional connectivity. Seventeen healthy, young, physically active female athletes completed 6 weeks of augmented neuromuscular training (aNMT) utilizing real-time, interactive visual biofeedback and 13 served as untrained controls. A drop vertical jump and resting state functional magnetic resonance imaging were separately completed at pre- and posttest time points to assess sensorimotor adaptation. The aNMT group had a significant reduction in peak knee abduction moment (pKAM) compared to controls (p = .03, d = 0.71). The aNMT group also exhibited a significant increase in functional connectivity between the right supplementary motor area and the left thalamus (p = .0473 after false discovery rate correction). Greater percent change in pKAM was also related to increased connectivity between the right cerebellum and right thalamus for the aNMT group (p = .0292 after false discovery rate correction, r2  = .62). No significant changes were observed for the controls (ps > .05). Our data provide preliminary evidence of potential neural mechanisms for aNMT-induced motor adaptations that reduce injury risk. Future research is warranted to understand the role of neuromuscular training alone and how each component of aNMT influences biomechanics and functional connectivity.

Limited positive effects on jump-landing technique in girls but not in boys after 8 weeks of injury prevention exercise training in youth football.

PURPOSE: To evaluate changes in jump-landing technique in football-playing boys and girls after 8 weeks of injury prevention training. METHODS: Four boys' and four girls' teams (mean age 14.1 ± 0.8 years) were instructed to use either the original Knee Control injury prevention exercise programme (IPEP) or a further developed IPEP, Knee Control + , at every training session for 8 weeks. Baseline and follow-up testing of jump-landing technique included drop vertical jumps (DVJ), assessed subjectively and with two-dimensional movement analysis, and tuck jump assessment (TJA). RESULTS: Only minor differences in intervention effects were seen between the two IPEPs, and results are therefore presented for both intervention groups combined. At baseline 30% of the boys showed good knee control during the DVJ, normalised knee separation distances of 77-96% (versus hip) and a median of 3 flaws during the TJA. Among girls, 22% showed good knee control, normalised knee separation distances of 67-86% and a median of 4 flaws during the TJA. At follow-up, boys and girls performed significantly more jumps during TJA. No changes in jump-landing technique were seen in boys, whereas girls improved their knee flexion angle at initial contact in the DVJ (mean change + 4.7°, p < 0.001, 95% CI 2.36-6.99, d = 0.7) and their TJA total score (- 1 point, p = 0.045, r = - 0.4). CONCLUSION: The study showed small positive effects on jump-landing technique in girls, but not in boys, after 8 weeks of injury prevention training. LEVEL OF EVIDENCE: Level II. TRIAL REGISTRATION: Clinical Trials gov identifier: NCT03251404.

Hip biomechanics differ in responders and non-responders to an ACL injury prevention program.

PURPOSE: To investigate the differences in demographic, anthropometric, biomechanical, and/or performance variables between those that do (responders) and do not (non-responders) exhibit reductions in knee abduction moments after an anterior cruciate ligament injury prevention program (ACL-IPP). METHODS: Forty-three adolescent female athletes completed biomechanical (3D motion analysis of a drop vertical jump) and performance testing before and after randomization into a 6-week ACL-IPP. Participants were classified into responders and non-responders based on their level of reduction of knee abduction moment from pre- to post-test. RESULTS: Compared to non-responders, responders exhibited increased hip adduction excursion at baseline (p = 0.02) and trended towards attending more training sessions (p = 0.07) and participating in soccer and not basketball (p = 0.07). Responders also showed greater improvements in hip flexion angles (p = 0.02) and moments (p < 0.001), and knee abduction angles (p < 0.001) and excursions (p = 0.001). There were no significant differences in age or experience with prior injury prevention programs (n.s.). CONCLUSIONS: After an ACL-IPP, athletes that exhibit the greatest reduction in knee abduction moments exhibit greater hip adduction excursion at baseline and show corresponding improvements in hip flexion and knee abduction kinematics and hip flexion moments. These results can help clinicians prospectively identify individuals that may not respond to an ACL-IPP and target individualized training for those at risk of injury. LEVEL OF EVIDENCE: I. CLINICAL TRIAL REGISTRATION NUMBER: Clinicaltrials.gov NCT02530333.

Oral contraceptives provide protection against anterior cruciate ligament tears: a national database study of 165,748 female patients.

Objective: Anterior cruciate ligament (ACL) tears are more prevalent in females than males. One of the factors responsible for this may be the variation in levels of estrogen and progesterone. The purpose of this study was to determine the potentially protective effects of oral contraceptive pills (OCPs) on ACL tears.Methods: The PearlDiver database (www.pearldiverinc.com, Fort Wayne, IN) was queried for all OCP users amongst females aged 15-49. Female experiencing an ACL tear and undergoing surgery (CPT 29,888) were compared to a control group of females undergoing surgery for an ACL tear, but not on OCPs. Chi-squared testing was used to assess for significant differences in the rate of ACL reconstruction for the OCP and non-OCP users, according to age groups broken down into age intervals of 5 years.Results: There were a total 82,874 patients in both the OCP and non-OCP groups. There was a total of 569 (0.69%) ACL reconstructions in the non-OCP group and 465 (0.56%) in the OCP group (p< 0.001). In the non-OCP group, patients aged 15-19 accounted for 29.35% of all ACL reconstructions, whereas, in the OCP group, this same age group only accounted for 13.33%. Among all age groups, the odds ratios for experiencing an ACL reconstruction while on OCP was 0.82 (χ2 = 0.001, 95% CI 0.72-0.92) compared to not using OCP. This protective effect was driven primarily by the 15-19 age group (odds ratio 0.37 (χ2 < 0.001, 95% CI 0.27-0.50)). The number need to treat for OCP usage in the 15-19 age group was six patients.Conclusions: OCPs have a protective effect on ACL tear, especially in the 15-19 age group, which exhibited a 63% reduction in the rate of tear. Consideration should be given to prescribing OCPs to younger athletes, after careful assessment of the risks of these commonly prescribed medications.Level of evidence: III.

Early intervention of swimming exercises attenuate articular cartilage destruction in a rat model of anterior cruciate ligament and meniscus knee injuries.

AIM: The anterior cruciate ligament (ACL) and meniscus injuries often cause post-traumatic knee osteoarthritis (PTOA), which can place great limitations on patients. But to date there is no effective therapy to delay the progression of cartilage destruction in PTOA. This study aimed to compare the effects of early versus delayed swimming exercise on the chondroprotective effects in a rat PTOA model with ACL and meniscus injuries. MAIN METHODS: Thirty-two adult male Sprague-Dawley rats received unilateral ACL transection and medial meniscectomy (ACLMT). These were randomly allocated to four groups: early swimming (eSW), delayed swimming (dSW), sham-operated early swimming (sham-eSW) and sham-operated delayed swimming (sham-dSW). Swimming (30 min per session) continuing for 28 days was started three days and three months after ACLMT surgery as a protocol for eSW and dSW intervention. Cartilage quality was assessed by Mankin HHGS examination (H&E, Safranin-O stain) and collagen type II (CoII) and matrix metalloproteases-13 (MMP13) immunohistochemistry. KEY FINDINGS: ACLMT induced the PTOA histopathological changes, inhibited CoII and enhanced MMP13 expressions in cartilage for both sham-eSW and sham-dSW groups. eSW intervention significantly enhanced CoII expression and suppressed MMP13 overexpression in superficial and transitional zones of cartilage, as well as better Mankin scores, corresponding to sham-swimming controls (P < 0.05). dSW intervention provided less enhancement of CoII expression and improvement of histopathological scoring, but significantly reduced MMP13 overexpression compared to animals in eSW (P < 0.05). SIGNIFICANCE: Early intervention by swimming at very early stages of cartilage damage provides greater benefits than delayed intervention when PTOA has already developed.

[Return to play after anterior cruciate ligament reconstruction].

After anterior cruciate ligament (ACL) reconstruction, 30% of the patients aged 20 years and younger experience a second injury. Studies imply, that with the right rehabilitation and testing many of these injuries can be prevented. Return to play should not be allowed until nine months after surgery at the earliest and should be based on relevant testing of strength, function and mental readiness.

Injury prevention and return to play strategies in elite football: no consent between players and team coaches.

INTRODUCTION: Injuries are a common problem in football. To improve prevention strategies, the players' (p) and coaches' (c) views need to be disclosed as they have a strong impact on return to play decisions. The aim of this study is to reveal current opinions with regard to injury prevention and return to play strategies to introduce new strategies in elite football. MATERIALS AND METHODS: In a retrospective data analysis of elite salaried football players (n = 486) and team coaches (n = 88), a detailed investigation by means of a standardized questionnaire was carried out. In a preseason period of the 2015/16 season and as part of a large interventional research project in elite salaried German football, a request about players' and team coaches' knowledge and opinions was performed. Topics such as injury prevention, return to play after injuries, the importance of screening tests, general problems of injuries in football, or the decision-making in terms of prevention and return to play in elite football were investigated. RESULTS: The study revealed a high interest in injury prevention and screening tests among players and coaches (p 82.5%; c 99.1%). The participants of the study reported warm-up exercises (p 76.4%; c 74.7%), regeneration training (p 54.1%; c 56.3%), and core stability (p 53.8; c 70.1%) as the most important prevention methods, but the additional investigation of the teams' current daily training routine showed that the transfer is incomplete. Coaches are more familiar with scientific published warm-up programs like FIFA 11 + than players (42.5 vs. 12.6; p < 0.001). Knee injuries (p 90.7%; c 93.1%) and ACL injuries in particular were reported as the most severe and common problem in elite football. Players and coaches expressed different attitudes concerning return to play decisions. While players want to decide themselves (81.4%), team coaches consult medical advice ahead of the decision of return to play after injuries (83.5%; p < 0.001). Decisions against the doctor's recommendation are often made by both groups (p 64.4% vs. c 87.1%; p < 0.001). CONCLUSION: The basic knowledge of prevention and injuries is sufficient in elite football, but the transfer from theoretical knowledge to practical routine is suboptimal. The study also shows possibilities to improve the prevention process and communication between players, coaches, doctors, and physiotherapists, while there is no consent between players and coaches regarding return to play decision.

2018 International Olympic Committee consensus statement on prevention, diagnosis and management of paediatric anterior cruciate ligament (ACL) injuries.

In October 2017, the International Olympic Committee hosted an international expert group of physiotherapists and orthopaedic surgeons who specialise in treating and researching paediatric ACL injuries. Representatives from the American Orthopaedic Society for Sports Medicine, European Paediatric Orthopaedic Society, European Society for Sports Traumatology, Knee Surgery & Arthroscopy, International Society of Arthroscopy Knee Surgery and Orthopaedic Sports Medicine, Pediatric Orthopaedic Society of North America and Sociedad Latinoamericana de Artroscopia, Rodilla y Deporte attended. Physiotherapists and orthopaedic surgeons with clinical and research experience in the field, and an ethics expert with substantial experience in the area of sports injuries also participated. Injury management is challenging in the current landscape of clinical uncertainty and limited scientific knowledge. Injury management decisions also occur against the backdrop of the complexity of shared decision-making with children and the potential long-term ramifications of the injury. This consensus statement addresses six fundamental clinical questions regarding the prevention, diagnosis and management of paediatric ACL injuries. The aim of this consensus statement is to provide a comprehensive, evidence-informed summary to support the clinician, and help children with ACL injury and their parents/guardians make the best possible decisions.

A 6-week warm-up injury prevention programme results in minimal biomechanical changes during jump landings: a randomized controlled trial.

PURPOSE: To examine the extent to which an ACL injury prevention programme modifies lower extremity biomechanics during single- and double-leg landing tasks in both the sagittal and frontal plane. It was hypothesized that the training programme would elicit improvements in lower extremity biomechanics, but that these improvements would be greater during a double-leg sagittal plane landing task than tasks performed on a single leg or in the frontal plane. METHODS: Ninety-seven competitive multi-directional sport athletes that competed at the middle- or high-school level were cluster randomized into intervention (n = 48, age = 15.4 ± 1.0 years, height = 1.7 ± 0.07 m, mass = 59.9 ± 11.0 kg) and control (n = 49, age = 15.7 ± 1.6 years, height = 1.7 ± 0.06 m, mass = 60.4 ± 7.7 kg) groups. The intervention group participated in an established 6-week warm-up-based ACL injury prevention programme. Three-dimensional biomechanical analyses of a double- (SAG-DL) and single-leg (SAG-SL) sagittal, and double- (FRONT-DL) and single-leg (FRONT-SL) frontal plane jump landing tasks were tested before and after the intervention. Peak angles, excursions, and external joint moments were analysed for group differences using 2 (group) × 4 (task) repeated measures MANOVA models of delta scores (post-pre-test value) (α < 0.05). RESULTS: Relative to the control group, no significant biomechanical changes were identified in the intervention group for any of the tasks (n.s.). However, a group by task interaction was identified for knee abduction (λ = 0.80, p = 0.02), such that participants in the intervention group showed relative decreases in knee abduction moments during the SAG-DL compared to the SAG-SL (p = 0.005; d = 0.45, CI = 0.04-0.85) task. CONCLUSION: A 6-week warm-up-based ACL injury prevention programme resulted in no significant biomechanical changes during a variety of multi-directional jump landings. Clinically, future prevention programmes should provide a greater training stimulus (intensity, volume), more specificity to tasks associated with the mechanism of ACL injury (single-leg, non-sagittal plane jump landings), and longer programme duration (> 6 weeks) to elicit meaningful biomechanical changes. LEVEL OF EVIDENCE: I.

Evaluation of Agreement Between Participant and Expert on Jump-Landing Characteristics During a 4-Week Intervention.

CONTEXT: Feedback is an important factor in interventions designed to reduce anterior cruciate ligament injury risk. Self-analysis feedback requires participants to self-critique their jump-landing mechanics; however, it is unknown if individuals can effectively self-analyze their own biomechanics and if this self-analysis agrees with observed biomechanical changes by an expert. OBJECTIVE: To determine agreement between an expert and participants on biomechanical errors committed during 3 of 12 sessions, which were part of an intervention to change jump-landing biomechanics in healthy females. DESIGN: Descriptive analysis. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: Healthy recreationally active females with no history of lower-extremity fracture or surgery. INTERVENTIONS: Participants completed a 4-week, 12-session feedback intervention. Each intervention session lasted approximately 15 minutes and included asking participants to perform 6 sets of 6 jumps off a 30-cm-high box placed 50% of their height away from the target landing area. Participants performed self-analysis feedback and received expert feedback on 7 different jump-landing criteria following each set of jumps. MAIN OUTCOME MEASURES: Data were coded, and agreement between the expert and the participant was assessed using Cohen's unweighted kappa for sessions 1, 6, and 12. RESULTS: There was agreement between the expert and participants for 0/7 criteria for session 1, 3/7 criteria for session 6, and 4/7 criteria for session 12. CONCLUSIONS: Participants demonstrated some agreement with the expert when evaluating their jump-landing biomechanics. Self-analysis feedback may not replace what an expert can provide; both types of feedback may be better used in conjunction to produce significant biomechanical changes. Changes made by the participant may not translate into biomechanical changes during a real-life game or practice situation. Future research should continue to investigate effective interventions to reduce injury risk.

Evidence-based concepts for prevention of knee and ACL injuries. 2017 guidelines of the ligament committee of the German Knee Society (DKG).

INTRODUCTION: Knee injuries and especially anterior cruciate ligament (ACL) tears are frequent in athletes. Therefore, primary and secondary prevention of sports-related lower limb injuries is an ongoing topic of interest. The aim of present study was to establish guidelines for the prevention of knee and ACL injuries on the basis of evidence-based concepts represented in current literature. METHODS: A comprehensive literature review regarding prevention programs for knee and ACL injuries was conducted. RESULTS: Several modifiable and non-modifiable risk factors for knee injuries in athletes have been reported in literature. Referring to the ACL, specific injury mechanisms have been identified and are well understood. In particular, it has been demonstrated that dynamic valgus is one of the most important modifiable risk factors. Simple tests like the drop jump test have shown their efficacy in screening and detecting athletes at risk. There is only few evidence for the preventive effect on knee and ACL injuries by single exercises. However, in order to prevent or correct endangering movement patterns including dynamic valgus, several complex prevention programs have been developed in the past. These prevention programs are included in standard warm-up exercises and are focusing on muscle strength, balance, and proprioception, as well as running and flexibility. It is reported that these training programs can reduce the incidence of knee injuries by up to 27% and ACL injuries by up to 51%. CONCLUSIONS: Screening, identification, and correction of endangering movement patterns like the dynamic valgus are the first crucial steps in order to prevent knee and ACL injuries in athletes. Furthermore, jumping, running and flexibility exercises as well as balance and strength training are proven to reduce the incidence of these injuries and should, therefore, be integrated into the regular warm up program. Appropriate complete prevention programs are freely accessible via the Internet and should be adapted to the specific sport disciplines.

Transfer of improved movement technique after receiving verbal external focus and video instruction.

PURPOSE: It is unknown how movement patterns that are learned carry over to the field. The objective was to determine whether training during a jump-landing task would transfer to lower extremity kinematics and kinetics during sidestep cutting. METHODS: Forty healthy athletes were assigned to the verbal internal focus (IF, n = 10), verbal external focus (EF, n = 10), video (VI, n = 10) or control (CTRL, n = 10) group. A jump-landing task was performed as baseline followed by training blocks (TR1 and TR2) and a post-test. Group-specific instructions were given in TR1 and TR2. In addition, participants in the IF, EF and VI groups were free to ask for feedback after every jump during TR1 and TR2. Retention was tested after 1 week. Transfer of learned skill was determined by having participants perform a 45° unanticipated sidestep cutting task. 3D hip, knee and ankle kinematics and kinetics were the main outcome measures. RESULTS: During sidestep cutting, the VI group showed greater hip flexion ROM compared to the EF and IF groups (p < 0.001). The EF (p < 0.036) and VI (p < 0.004) groups had greater knee flexion ROM compared to the IF group. CONCLUSIONS: Improved jump-landing technique carried over to sidestep cutting when stimulating an external attentional focus combined with self-controlled feedback. Transfer to more sport-specific skills may demonstrate potential to reduce injuries on the field. Clinicians and practitioners are encouraged to apply instructions that stimulate an external focus of attention, of which visual instructions seem to be very powerful. LEVEL OF EVIDENCE: II.