Critical components of neuromuscular training to reduce ACL injury risk in female athletes: meta-regression analysis

Orthopaedic medical examination for young amateur athletes: a repeated cross-sectional study from 2014 to 2018

OBJECTIVES

Medical examinations for adult elite athletes are performed all over the world, however, no studies in the relevant English literature have reported on orthopaedic medical examinations for young amateur athletes. The purpose of this study was to report the results of orthopaedic medical examinations of the spine and lower extremities in young amateur athletes.

METHODS

This repeated cross-sectional study from 2014 to 2018 included a total of 323 young amateur athletes (age, 12-18 years) who were active in one of the following four sports: boxing, canoeing, weightlifting and track and field. The orthopaedic medical examination consisted of six assessments (physical examinations, the generalised joint laxity, muscle and joint tightness, static alignment and muscle volume of the lower extremities and the medial longitudinal arch of the foot). Questions regarding pain in the spine and lower extremities were also performed.

RESULTS

Among 323 young amateur athletes, 17 (5.3%) had received orthopaedic treatment at the time of the medical examination, with spondylolysis being the most common cause (29.4%, 5/17). Among 306 young athletes who had not received orthopaedic treatment, 61 (19.9%) had at least one positive finding in physical examinations or had pain in the spine or lower extremities. Anterior drawer test of the ankle and Kemp test for the spine accounted for 34% and 28% of positive findings, respectively. Low back pain and knee pain accounted for 58% and 16% of pain, respectively.

CONCLUSIONS

The present study showed that approximately one-fifth of young amateur athletes who had not received orthopaedic treatment had pain in the spine and lower extremities and positive findings in physical examinations that may require orthopaedic treatments. In addition to the early detection of injuries, orthopaedic medical examinations for young amateur athletes provide an opportunity to educate such athletes.

Knee Kinematics During Landing: Is It Really a Predictor of Acute Noncontact Knee Injuries in Athletes? A Systematic Review and Meta-analysis

BACKGROUND

Although knee kinematics during landing tasks has traditionally been considered to predict noncontact knee injuries, the predictive association between noncontact knee injuries and kinematic and kinetic variables remains unclear.

PURPOSE

To systematically review the association between kinematic and kinetic variables from biomechanical evaluation during landing tasks and subsequent acute noncontact knee injuries in athletes.

STUDY DESIGN

Systematic review; Level of evidence, 2.

METHODS

Databases used for searches were MEDLINE, LILACS, IBECS, CINAHL, SPORTDiscus, SCIELO, IME, ScienceDirect, and Cochrane from database inception to May 2020. Manual reference checks, articles published online ahead of print, and citation tracking were also considered. Eligibility criteria included prospective studies evaluating frontal and sagittal plane kinematics and kinetics of landing tasks and their association with subsequent acute noncontact knee injuries in athletes.

RESULTS

A total of 13 studies met the eligibility criteria, capturing 333 acute noncontact knee injuries in 8689 participants. A meta-analysis revealed no significant effects for any kinematic and kinetic variable with regard to subsequent noncontact knee injuries.

CONCLUSION

No kinetic or kinematic variables from landing tasks had a significant association with acute noncontact knee injuries. Therefore, the role and application of the landing assessment for predicting acute noncontact knee injuries are limited and unclear, particularly given the heterogeneity and risk of bias of studies to date.

Feedback cues improve the alignment and technique of children performing ACL injury prevention exercises

OBJECTIVES

The appropriateness of neuromuscular training exercises across different age groups has not yet been investigated, particularly in younger children. The purpose of this study was to determine which neuromuscular training exercises can be performed with proper neutral alignment in various age groups.

METHODS

Seven exercises were selected for evaluation in children ranging from 8 to 17 years of age who were recruited from schools and youth sports organisations. Participants completed two trials of each exercise and were judged on maintaining neutral body alignment after receiving visual/verbal instruction on the first trial and feedback cues on the second trial. Three evaluators judged each exercise, which was deemed as correct when at least two evaluators agreed that neutral alignment was maintained. Comparisons were made across ages and between sex using the χ² test or Fisher's exact test. The proportions of participants who performed the exercise correctly were also compared before and after feedback cues were provided.

RESULTS

A total of 360 participants were evaluated (8-11 years: 165, 54% female; 12-15 years: 136, 40% female, 16-17 years: 59, 53% female). There were no significant differences in performance across ages and sex for nearly all exercises. The majority of children were not able to complete the exercises with proper alignment. The use of feedback cues significantly increased the proportion of participants who correctly completed the exercise (p<0.001).

CONCLUSIONS

These results demonstrate the importance of training coaches and physical education teachers to provide cues that reinforce proper technique during anterior cruciate ligament injury prevention exercises. Children should perform common neuromuscular training exercises with feedback on proper technique.

LEVEL OF EVIDENCE

IV (case series).

Effects of a 10 vs. 20-Min Injury Prevention Program on Neuromuscular and Functional Performance in Adolescent Football Players

Background

Regular injury prevention training is not only effective in reducing sports injury rates, but also in improving neuromuscular and performance-related variables. However, it is currently unknown if this effect can be modified by varying the training dosage.

Objective

To compare the effects of two injury prevention programmes with a different training duration on neuromuscular control and functional performance in adolescent football players.

Methods

342 (15.4 ± 1.7 years) male football players from 18 teams were initially included. The teams were cluster-randomized into two intervention groups. Both groups performed an injury prevention program twice a week during one football season (10 months) using the same exercises but a different duration. One intervention group (INT10, n = 175) performed the program for 10 min, while the other intervention group (INT20, n = 167) for 20 min. At the beginning and end of the season, balance control (Balance Error Scoring System = BESS), jump performance (Squat Jump, Countermovement Jump) and flexibility (Sit and Reach Test, ankle flexibility, hip flexibility) tests were performed. For the final analysis, nine teams with 104 players were considered.

Results

Significant group by time interactions were found for the sit and reach test (p < 0.001) and ankle flexibility (p < 0.001) with higher improvements in the INT20 group. Improvements over the period of one season but no group differences were found for the BESS, Squat Jump and hip flexibility.

Conclusion

Within a single training session, performing structured neuromuscular training with a longer duration is more effective than a shorter duration for improving lower extremity flexibility.

Landing Error Scoring System scores change with knowledge of scoring criteria and prior performance

OBJECTIVE

To examine if the knowledge of scoring criteria and prior performance influence Landing Error Scoring System (LESS) outcomes.

DESIGN

Cross-sectional.

SETTING

Laboratory.

PARTICIPANTS

Thirty individuals.

MAIN OUTCOME MEASURES

The LESS was tested at Baseline and one week later under two conditions: Pre and Post information. For the Post condition, LESS items were explained to participants, as were their individual Baseline scores. Mean LESS scores and number of individuals categorized at high and low risk were compared between Pre and Post using paired t-tests and McNemar's tests, respectively. McNemar's tests were also used to compare proportions of specific LESS errors between Pre and Post conditions.

RESULTS

Mean LESS Post scores (4.7 ± 1.2 errors) were significantly lower than Pre scores (6.6 ± 2.0 errors, p < 0.001) as was the number of individuals at high risk (25 vs 10 participants, p < 0.001). A significantly lower proportion of participants scored an error for the joint displacement item of LESS Post compared to Pre condition (p < 0.001).

CONCLUSION

When using the LESS, it is important that tested individuals have no knowledge of scoring criteria or previous errors for a valid assessment of innate jump-landing movement patterns and injury risk.

Sex Differences in Lower Limb Proprioception and Mechanical Function Among Healthy Adults

Twenty-four healthy adults, including 12 females and 12 males, participated in the study. Each female participant completed three trials in three different phases of one menstrual cycle, which included follicular, ovulatory, and luteal phases. The study aimed to investigate whether there is any difference in joint kinetic sense, neuromuscular coordination, and isokinetic muscle strength (a) between healthy males and females at different phases of the menstrual cycle and (b) between females at different phases of the menstrual cycle. The outcome measures included the number of jumps in the square-hop test and ankle and knee proprioception, which were assessed by an electric-driven movable frame rotated at 0.4 deg/s and isokinetic muscle strength measured by a computerized dynamometer (Biodex). For the square-hop test (p = .006), ankle dorsiflexion/plantar flexion (p < .05), knee flexion/extension (p < .05), the relative peak torque of the isokinetic muscle strength at the 60° and 180° knee flexion/extension (p < .001), and the 30° and 120° ankle plantar flexion/dorsiflexion (p < .05) between females and males showed significant differences. For the females at different phases of the menstrual cycle, significant differences were found on ankle dorsiflexion (p = .003), plantar flexion (p = .023), knee extension (p = .029), the square-hop test (p = .036), and relative peak torque of isokinetic muscle strength at 180° knee flexion (p = .029). This study demonstrated that there are sex differences in lower limb proprioception and mechanical function. Females at ovulatory and luteal phases have better lower limb proprioception than at the follicular phase.

Using machine learning to improve our understanding of injury risk and prediction in elite male youth football players

OBJECTIVES

The purpose of this study was to examine whether the use of machine learning improved the ability of a neuromuscular screen to identify injury risk factors in elite male youth football players.

DESIGN

Prospective cohort study.

METHODS

355 elite youth football players aged 10-18 years old completed a prospective pre-season neuromuscular screen that included anthropometric measures of size, as well as single leg countermovement jump (SLCMJ), single leg hop for distance (SLHD), 75% hop distance and stick (75%Hop), Y-balance anterior reach and tuck jump assessment. Injury incidence was monitored over one competitive season. Risk profiling was assessed using traditional regression analyses and compared to supervised machine learning algorithms constructed using decision trees.

RESULTS

Using continuous data, multivariate logistic analysis identified SLCMJ asymmetry as the sole significant predictor of injury (OR 0.94, 0.92-0.97, p<0.001), with a specificity of 97.7% and sensitivity of 15.2% giving an AUC of 0.661. The best performing decision tree model provided a specificity of 74.2% and sensitivity of 55.6% with an AUC of 0.663. All variables contributed to the final machine model, with asymmetry in the SLCMJ, 75%Hop and Y-balance, plus tuck jump knee valgus and anthropometrics being the most frequent contributors.

CONCLUSIONS

Although both statistical methods reported similar accuracy, logistic regression provided very low sensitivity and only identified a single neuromuscular injury risk factor. The machine learning model provided much improved sensitivity to predict injury and identified interactions of asymmetry, knee valgus angle and body size as contributing factors to an injurious profile in youth football players.

Co-creation of a sport-specific anterior cruciate ligament injury risk reduction program for women: A concept mapping approach

OBJECTIVES

To engage physiotherapists experienced in female elite sport and athletes to co-create a sport-specific anterior cruciate ligament (ACL) injury risk reduction program.

DESIGN

Concept Mapping.

METHODS

The Concept Systems Global MAX™ web platform was used to collect and analyse data from 27 context and content experts (22 physiotherapists, 5 athletes). Participants brainstormed statements representing the critical elements that should be included in an ACL injury risk reduction program for women playing elite Australian Football (AF).

RESULTS

Twenty-two participants brainstormed 56 statements that were synthesised and edited to 62 statements. Statements were sorted into clusters by twenty-three participants and rated on importance and feasibility using six-point scales. Multidimensional scaling and cluster analysis identified a 5-cluster solution as follows: Football-specific preparation (15 statements); Movement skills (17 statements); Strength and conditioning (15 statements); Individual preparation (7 statements); and Education (8 statements). Calculation of mean ratings for each cluster and statement identified the Movement skills cluster as most important (mean=3.61 out of 5) and the Football-specific preparation cluster as most feasible (3.75 out of 5). By contrast, the Individual preparation cluster was rated the least important (mean=2.9 out of 5), and the least feasible (3.12 out of 5), to include in the program.

CONCLUSIONS

The five clusters of critical elements to include in an ACL injury risk reduction program for women playing elite AF, in order of most to least importance were: movement skills, football-specific preparation, education, strength and conditioning and individual preparation.

Individuals With an Anterior Cruciate Ligament-Reconstructed Knee Display Atypical Whole Body Movement Strategies but Normal Knee Robustness During Side-Hop Landings: A Finite Helical Axis Analysis

BACKGROUND

Atypical knee joint biomechanics after anterior cruciate ligament reconstruction (ACLR) are common. It is, however, unclear whether knee robustness (ability to tolerate perturbation and maintain joint configuration) and whole body movement strategies are compromised after ACLR.

PURPOSE

To investigate landing control after ACLR with regard to dynamic knee robustness and whole body movement strategies during sports-mimicking side hops, and to evaluate functional performance of hop tests and knee strength.

STUDY DESIGN

Controlled laboratory study.

METHODS

An 8-camera motion capture system and 2 synchronized force plates were used to calculate joint angles and moments during standardized rebound side-hop landings performed by 32 individuals with an ACL-reconstructed knee (ACLR group; median, 16.0 months after reconstruction with hamstring tendon graft [interquartile range, 35.2 months]) and 32 matched asymptomatic controls (CTRL). Dynamic knee robustness was quantified using a finite helical axis approach, providing discrete values quantifying divergence of knee joint movements from flexion-extension (higher relative frontal and/or transverse plane motion equaled lower robustness) during momentary helical rotation intervals of 10°. Multivariate analyses of movement strategies included trunk, hip, and knee angles at initial contact and during landing and hip and knee peak moments during landing, comparing ACLR and CTRL, as well as legs within groups.

RESULTS

Knee robustness was lower for the first 10° motion interval after initial contact and then successively stabilized for both groups and legs. When landing with the injured leg, the ACLR group, as compared with the contralateral leg and/or CTRL, demonstrated significantly greater flexion of the trunk, hip, and knee; greater hip flexion moment; less knee flexion moment; and smaller angle but greater moment of knee internal rotation. The ACLR group also had lower but acceptable hop and strength performances (ratios to noninjured leg >90%) except for knee flexion strength (12% deficit).

CONCLUSION

Knee robustness was not affected by ACLR during side-hop landings, but alterations in movement strategies were seen for the trunk, hip, and knee, as well as long-term deficits in knee flexion strength.

CLINICAL RELEVANCE

Knee robustness is lowest immediately after landing for both the ACLR group and the CTRL and should be targeted in training to reduce knee injury risk. Assessment of movement strategies during side-hop landings after ACLR should consider a whole body approach.

Injury prevention programmes with plyometric and strengthening exercises improve on-field performance: a systematic review

Importance

Injury prevention programmes (IPPs) have been demonstrated to be highly efficacious in protecting young athletes from anterior cruciate ligament and other lower-extremity injuries. However, the effectiveness of these programme in practice has been limited due to poor adherence among coaches of organised sports teams.

Objective

A change in messaging from injury reduction to performance enhancement may be an effective strategy for improving adherence. We conducted a systematic review to address whether implementing IPP can also provide benefits on sports performance as measured by on-field tests.

Evidence review

Data Sources: PubMed, EMBASE and Cochrane Library databases were searched from January 2000 to August 2018.

Study Selection: English-language studies were selected if they evaluated on-field performance testing before and after participation in the IPP or compared with another programme/control. No limitations were placed on study design or study population. Studies were excluded if they evaluated programme without an explicit focus on injury prevention or reported on injury risk factors that were not related to athletic performance.

Study design

Systematic review

Data extraction

Study design, population, sport and level, comparison group and duration/frequency of the IPP were extracted from full-text articles. The results of performance testing were summarised into the following categories: balance, sprinting, agility, jumping, physical fitness and sport-specific skills.

Findings

The evidence shows that IPP can have beneficial effects on measures of sports performance and physical fitness. Factors that resulted in significant improvement included longer frequency and duration of the programme, as well as inclusion of plyometric and muscle strengthening exercises.

Conclusions

There is a wide variety of measures used for athletic performance. IPPs that are done more frequently for longer durations and that include strengthening and plyometric exercises have been shown to improve athletic performance. Enhanced performance with tests that can be conducted on the field with existing equipment may help convince coaches and athletes to improve adherence with the IPP exercises.

Level of evidence

Level II

A novel test reliably captures hip and knee kinematics and kinetics during unanticipated/anticipated diagonal hops in individuals with anterior cruciate ligament reconstruction

Unanticipated land-and-cut maneuvers might emulate lower limb mechanics associated with anterior cruciate ligament (ACL) injury. Reliability studies on landing mechanics of such maneuvers are however lacking. This study investigated feasibility and within-session reliability of landing mechanics of a novel one-leg double-hop test, mimicking a land-and-cut maneuver, in individuals with ACL reconstruction (ACLR). Our test comprised a forward hop followed by a diagonal hop in either of two directions (medial/lateral) under anticipated and unanticipated conditions. Twenty individuals with a unilateral ACLR (aged 24.2 ± 4.2 years, 0.7-10.8 years post-surgery) performed three successful hops/direction per leg. We determined reliability (intraclass correlation coefficient [ICC]) and agreement (standard error of measurement [SEM]) of 3-dimensional hip and knee angles and moments during the deceleration phase of the land-and-cut maneuver (vulnerable for non-contact ACL injuries). Mean success rate for unanticipated hops was 71-77% and for anticipated hops 91-95%. Both limbs demonstrated moderate-excellent reliability (ICC 95% confidence intervals: 0.50-0.99) for almost all hip and knee peak angles and moments in all planes and conditions, with a few exceptions: poor-good reliability for hip and knee frontal and/or transverse plane variables, especially for lateral diagonal hops. The SEMs were ≤5° and ≤0.23 N·m/kg·m for most peak angles and moments, respectively. Our test seems feasible and showed satisfactory reliability for most hip and knee angles and moments; however, low knee abduction and internal rotation angles and moments, and moderate reliability of these moments deserve consideration. The test appears to challenge dynamic knee control and may prove valuable in evaluation during knee rehabilitation.

Fatigue Increases Dynamic Knee Valgus in Youth Athletes: Results From a Field-Based Drop-Jump Test

PURPOSE

To determine whether fatigue increases dynamic knee valgus in adolescent athletes, as measured after a standardized exercise protocol and video-based drop-jump test. A secondary aim was to determine whether individual risk factors place certain athletes at increased risk for dynamic knee valgus.

METHODS

Athletes aged 14 to 18 years were recruited for this video analysis study. Athletes were recorded performing a standard drop-jump to assess dynamic valgus. Participants then completed a standardized exercise protocol. Fatigue was quantified using a maximum vertical jump, which was compared with pre-exercise values. The drop-jump was repeated postexercise. All drop-jump recordings were randomized and scored for dynamic valgus by 11 blinded reviewers. Univariate analysis was performed to identify characteristics that predisposed athletes to increased dynamic valgus.

RESULTS

Eighty-five (47 female, 38 male) athletes with an average age of 15.4 years were included in this study. Forty-nine percent of athletes demonstrated an increase in dynamic valgus determined by drop-jump assessment after exercise. A significantly greater percentage of athletes were graded "medium or high risk" in jumps recorded after the exercise protocol (68%) as compared with before the exercise protocol (44%; P < .01). Female athletes (P < .01) and those older than 15 years of age (P < .01) were the most affected by fatigue.

CONCLUSIONS

In conclusion, our study found that exercise increases dynamic knee valgus in youth athletes. Female athletes and those older than 15 years of age were most significantly affected by exercise. Greater fatigue levels were found to correlate with an increase in dynamic knee valgus, which may place athletes at greater anterior cruciate ligament injury risk. The field-based exercise drop-jump test is a low-cost and reproducible screening tool to identify at-risk athletes who could possibly benefit from anterior cruciate ligament injury-prevention strategies.

LEVEL OF EVIDENCE

III, Comparative trial.

Editorial Commentary: Considering Fatigue When Assessing Athletes for Dynamic Knee Valgus: Is This the Next Big Step in Identifying Anterior Cruciate Ligament Injury Risk?

Excessive dynamic knee valgus during jumping is a poor movement strategy that has been well-documented as a risk factor for anterior cruciate ligament injury. Yet, there has been little progress in the translation of findings from high-tech motion capture laboratories to clinically applicable settings. One barrier to widespread use is expensive technology that requires time; therefore, field-based efficient assessment tools that can be used by several types of clinicians are desperately needed. Further, fatigue can influence dynamic knee valgus and should be considered when assessing or conditioning athletes.

Eccentric Resistance Training in Youth: Perspectives for Long-Term Athletic Development

The purpose of this narrative review is to discuss the role of eccentric resistance training in youth and how this training modality can be utilized within long-term physical development. Current literature on responses to eccentric exercise in youth has demonstrated that potential concerns, such as fatigue and muscle damage, compared to adults are not supported. Considering the importance of resistance training for youth athletes and the benefits of eccentric training in enhancing strength, power, speed, and resistance to injury, its inclusion throughout youth may be warranted. In this review we provide a brief overview of the physiological responses to exercise in youth with specific reference to the different responses to eccentric resistance training between children, adolescents, and adults. Thereafter, we discuss the importance of ensuring that force absorption qualities are trained throughout youth and how these may be influenced by growth and maturation. In particular, we propose practical methods on how eccentric resistance training methods can be implemented in youth via the inclusion of efficient landing mechanics, eccentric hamstrings strengthening and flywheel inertia training. This article proposes that the use of eccentric resistance training in youth should be considered a necessity to help develop both physical qualities that underpin sporting performance, as well as reducing injury risk. However, as with any other training modality implemented within youth, careful consideration should be given in accordance with an individual's maturity status, training history and technical competency as well as being underpinned by current long-term physical development guidelines.

Variation in ACL and MCL Strain Before Initial Contact Is Dependent on Injury Risk Level During Simulated Landings

Background

The existent literature has well explored knee ligament kinetics and strain at and after initial contact (IC) during landing tasks. However, little is known about knee ligament biomechanics in flight before IC.

Purpose

To quantify and compare change in anterior cruciate ligament (ACL) and medial collateral ligament (MCL) strain before IC relative to after IC.

Study Design

Descriptive laboratory study.

Methods

A total of 40 cadaveric specimens were analyzed after being subjected to simulated landings in a mechanical impact simulator. External joint loads of varying magnitudes were applied to mimic relative injury risk load levels from an in vivo cohort and were coupled with an impulse force to represent initial ground contact. Implanted strain gauges continually recorded ligament strain. Kruskal-Wallis tests evaluated the significance of risk level and pre- and post-IC factors, while Wilcoxon each-pair tests evaluated differences within both factors.

Results

Strain responses during simulated landing tasks for the ACL (P ≥ .545) and MCL (P ≥ .489) were consistent after IC regardless of the level of relative injury risk simulated in each trial. Before IC, the level of injury risk kinetics applied to a specimen differentiated strain response in the ACL (P < .001) and MCL (P < .001), as higher risk profiles produced greater changes in ligament strain. Mean baseline strain was 4.0% in the ACL and 1.0% in the MCL. Mean change in strain from the ACL ranged from 0.1% to 3.9% pre-IC and from 2.9% to 5.7% post-IC, while the MCL ranged from 0.0% to 3.0% pre-IC and from 0.9% to 1.3% post-IC.

Conclusion

Within each ligament, post-IC strain response lacked statistical differences among simulated risk profiles, while pre-IC response was dependent on the risk profile simulated. Individually, neither pre- nor poststrain changes were enough to induce ACL failure, but when combined over the course of a full landing task, they could lead to rupture.

Clinical Relevance

Prevention and rehabilitation techniques should aim to limit the presence of increased risk biomechanics in flight before landing, as impulse delivery at IC is inevitable.

I spy with my little eye … a knee about to go 'pop'? Can coaches and sports medicine professionals predict who is at greater risk of ACL rupture?

Background

The vertical drop jump (VDJ) test is widely used for clinical assessment of ACL injury risk, but it is not clear whether such assessments are valid.

Aim

To examine if sports medicine professionals and coaches are able to identify players at risk of sustaining an ACL injury by visually assessing player performance during a VDJ test.

Methods

102 video clips of elite female handball and football players performing a baseline VDJ test were randomly extracted from a 738-person prospective cohort study that tracked ACL injuries. Of the sample, 20 of 102 went on to suffer an ACL injury. These 102 videos were uploaded to an online survey. Sports medicine professionals and coaches were invited to assess athlete performance and rate each clip with a number between 1 and 10 (1 representing low risk of sustaining an ACL injury and 10 representing high risk). Receiver operating characteristic analyses were used to assess classification accuracy and between-group differences were analysed using one-way analysis of variance.

Results

237 assessors completed the survey. Area under the curve values ranged from 0.36 to 0.60, with a mean score of 0.47, which is similar to random guessing. There were no significant differences in classification accuracy between groups (physicians, coaches, certified athletic trainers, researchers or physical therapists).

Conclusion

Assessors have poor predictive ability (no better than chance), indicating that visual assessment of a VDJ test is a poor test for assessing ACL injury risk in elite female handball and football players.

Evidence-Based Best-Practice Guidelines for Preventing Anterior Cruciate Ligament Injuries in Young Female Athletes: A Systematic Review and Meta-analysis

BACKGROUND

Injury prevention neuromuscular training (NMT) programs reduce the risk for anterior cruciate ligament (ACL) injury. However, variation in program characteristics limits the potential to delineate the most effective practices to optimize injury risk reduction.

PURPOSE

To evaluate the common and effective components included in ACL NMT programs and develop an efficient, user-friendly tool to assess the quality of ACL NMT programs.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

Study inclusion required (1) a prospective controlled trial study design, (2) an NMT intervention aimed to reduce incidence of ACL injury, (3) a comparison group, (4) ACL injury incidence, and (5) female participants. The following data were extracted: year of publication, study design, sample size and characteristics, and NMT characteristics including exercise type and number per session, volume, duration, training time, and implementer training. Analysis entailed both univariate subgroup and meta-regression techniques using random-effects models.

RESULTS

Eighteen studies were included in the meta-analyses, with a total of 27,231 participants, 347 sustaining an ACL injury. NMT reduced the risk for ACL injury from 1 in 54 to 1 in 111 (odds ratio [OR], 0.51; 95% CI, 0.37-0.69]). The overall mean training volume was 18.17 hours for the entire NMT (24.1 minutes per session, 2.51 times per week). Interventions targeting middle school or high school-aged athletes reduced injury risk (OR, 0.38; 95% CI, 0.24-0.60) to a greater degree than did interventions for college- or professional-aged athletes (OR, 0.65; 95% CI, 0.48-0.89). All interventions included some form of implementer training. Increased landing stabilization and lower body strength exercises during each session improved prophylactic benefits. A meta-regression model and simple checklist based on the aforementioned effective components (slope = -0.15, P = .0008; intercept = 0.04, P = .51) were developed to allow practitioners to evaluate the potential efficacy of their ACL NMT and optimize injury prevention effects.

CONCLUSION

Considering the aggregated evidence, we recommend that ACL NMT programs target younger athletes and use trained implementers who incorporate lower body strength exercises (ie, Nordic hamstrings, lunges, and heel-calf raises) with a specific focus on landing stabilization (jump/hop and hold) throughout their sport seasons.

CLINICAL RELEVANCE

Clinicians, coaches, athletes, parents, and practitioners can use the developed checklist to gain insight into the quality of their current ACL NMT practices and can use the tool to optimize programming for future ACL NMT to reduce ACL injury risk.

Neuromuscular Control of Vertical Jumps in Female Adolescents

BACKGROUND

Poor landing mechanics are considered deficits in neuromuscular control and risk factors for lower extremity injury. The Landing Error Scoring System (LESS) has been used to assess the neuromuscular control of landing mechanics for the first landing in a drop vertical jump (DVJ) task. However, the second DVJ landing may provide different results, warranting assessment.

HYPOTHESES

(1) LESS scores will differ between first and second DVJ landings across all female participants with (2) greater intraparticipant variability among the second landing compared with the first landing scores.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 4.

METHODS

A total of 13 gymnasts and 31 softball players (N = 44) performed 3 DVJ trials. The mean ± SD age of 44 female athletes was 16.46 ± 2.59 years. The LESS was scored using 2-dimensional video of each trial.

RESULTS

There was a significant difference between the first and second DVJ landings (P < 0.01). All participants demonstrated higher LESS scores (worse landing mechanics) during the second DVJ landing (10.10 ± 2.25) than the first landing (6.97 ± 2.72).

CONCLUSION

The initial landing in a DVJ has been the focus of neuromuscular control studies using the LESS. This study found worse neuromuscular control during the second DVJ landing, which highlights the importance of evaluating landing mechanics beyond the initial landing.

CLINICAL RELEVANCE

LESS analysis of both DVJ landings might improve neuromuscular control screening in female athletes and augment lower extremity and anterior cruciate ligament injury prevention programs.

Dynamic knee control and movement strategies in athletes and non-athletes in side hops: Implications for knee injury

Athletes exposed to rapid maneuvers need a high level of dynamic knee stability and robustness, while also controlling whole body movement, to decrease the risk of non-contact knee injury. The effects of high-level athletic training on such measures of movement control have not, however, been thoroughly evaluated. This study investigated whether elite athletes (who regularly perform knee-specific neuromuscular training) show greater dynamic knee robustness and/or different movement strategies than non-athletic controls, in relation to overall knee function. Thirty-nine women (19 athletes, 20 controls) performed standardized rebound side hops (SRSH) while a motion capture system synchronized with two force plates registered three-dimensional trunk, hip, and knee joint angles and moments. Dynamic knee robustness was evaluated using finite helical axis (FHA) inclination angles extracted from knee rotation intervals of 10°, analyzed with independent t tests. Angle and moment curves were analyzed with inferential methods for functional data. Athletes had superior knee function (less laxity, greater hop performances, and strength) but presented similar FHA inclination angles to controls. Movement strategies during the landing phase differed; athletes presented larger (a) hip flexion angles (during 9%-29% of the phase), (b) hip adduction moments (59%-99%), (c) hip internal rotation moments (83%-89%), and (d) knee flexion moments (79%-93%). Thus, elite athletes may have a greater ability than non-athletes to keep the knee robust while performing SRSH more efficiently through increased engagement of the hip. However, dynamic knee robustness associated with lower FHA inclination angles still show room for improvement, thus possibly decreasing knee injury risk.

Female athletes: managing risk and maximizing benefit

PURPOSE OF REVIEW

The purpose of this review is to provide an updated summary on the unique aspects of caring for female youth and adolescent athletes.

RECENT FINDINGS

Recent research on female athletes has led to a better understanding of injuries and conditions that are more likely to occur in female youth and adolescent athletes, including the frequency and severity of concussions, musculoskeletal injury such as involving the anterior cruciate ligament, and the female athlete triad. Social factors, such as the growing pressure to specialize in a sport particularly at an early age, also put young female athletes at risk for issues such as overuse injuries. Researchers continue to explore the benefits of athletic participation that extend beyond physical fitness.

SUMMARY

Female participation in youth sports has increased dramatically during the past 50 years. This has led to greater research on how to manage risks and maximize benefits for young female athletes, although there is still much to be learned. Providers should educate patients, parents, and coaches on both the increased risks for female athletes and ways to provide better support and accessibility of youth sports to all children.

Analysis of Lower Extremity Proprioception for Anterior Cruciate Ligament Injury Prevention: Current Opinion

Lower extremity musculoskeletal injuries-such as ACL injury-are common, and the majority of those injuries occur without external player contact. In order to prevent non-contact musculoskeletal injuries, athletes must rely on accurate sensory information (such as visual, vestibular, and somatosensory) and stabilize joints during athletic tasks. Previously, proprioception tests (the senses of joint position, movement, tension or force) have been examined using static tests. Due to the role of proprioception in achievement of joint stability, it is essential to explore the development of dynamic proprioception tests. In this current opinion, the basic background on proprioception is covered, and the research gaps and future directions are discussed.

Altered kinematics after anterior cruciate ligament reconstruction, and their role in the prevention of osteoarthritis

Background/Aims:

Anterior cruciate ligament injury is common, and anterior cruciate ligament reconstruction has become the standard of care that aims to restore knee stability, return to activity, and prevent secondary injury.

Methods:

A literature review was carried out using PubMed and Science Direct databases from 1998 through 2017. Search terms included: anterior cruciate ligament reconstruction and knee osteoarthritis; kinematics after anterior cruciate ligament reconstruction; and prevention of knee osteoarthritis. A total of 356 studies matched the search terms. After removing duplicates and any studies that were not relevant, 73 studies remained.

Findings:

Individuals usually have impaired neuromuscular control after reconstruction, and abnormal biomechanical patterns may lead to loading of cartilage areas that are not commonly loaded and that, longitudinally, can lead to osteoarthritis. The knee adduction moment indicates loading of the knee joint and has been associated with the development of osteoarthritis and altered gait mechanics have also been implicated in the increased rate of osteoarthritis after anterior cruciate ligament reconstruction, including differences in tibial rotation during walking. Furthermore, altered ankle joint mechanics may be the result of deviations in ankle joint alignment secondary to the structural changes at the knee. It is clear that abnormal mechanical stimulation may cause dysfunction of articular chondrocytes and breakdown of cartilage extracellular matrix, leading to articular cartilage degradation and chondrocyte death. The affected joint will progress to post-traumatic osteoarthritis.

Conclusions:

The restoration of normal knee anatomy and mechanics, such as returning the joint to normal function, improving muscle strength, functional movement prevention programmes, restoring gait symmetry and weight management are recommended.

Meta-analysis of meta-analyses of anterior cruciate ligament injury reduction training programs

Several meta-analyses have been published on the effectiveness of anterior cruciate ligament (ACL) injury prevention training programs to reduce ACL injury risk, with various degrees of risk reduction reported. The purpose of this research was to perform a systematic review and meta-analysis of overlapping meta-analyses evaluating the effectiveness of ACL injury prevention training programs so as to summarize the amount of reduction in risk for all ACL and non-contact ACL injuries into a single source, and determine if there were sex differences in the relative efficacy of ACL injury prevention training programs. Five databases (Medline, PubMed, Embase, CINAHL, and Cochrane) were searched to identify meta-analyses that evaluated the effectiveness of ACL injury prevention training programs on ACL injury risk. ACL injury data were extracted and the results from each meta-analysis were combined using a summary meta-analysis based on odds ratios (OR). Eight meta-analyses met eligibility criteria. Six of the eight only included data for female athletes. Summary meta-analysis showed an overall 50% reduction (OR = 0.5 [0.41-0.59]; I²  = 15%) in the risk of all ACL injuries in all athletes and a 67% reduction (OR = 0.33 [0.27-0.41]; I²  = 15%) for non-contact ACL injuries in females. This paper combines all previous meta-analyses into a single source and shows conclusive evidence that ACL injury prevention programs reduce the risk of all ACL injuries by half in all athletes and non-contact ACL injuries by two-thirds in female athletes. There is insufficient data to make conclusions as to the effectiveness of ACL injury prevention programs in male athletes. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2696-2708, 2018.

Risk factors associated with self-reported injury history in female youth soccer players

BACKGROUND

studies that investigate risk factors for musculoskeletal injuries in female youth athletes are limited, especially related to training attributes and position status.

OBJECTIVE

to determine risk factors including training attributes and position status for a self-reported musculoskeletal injury history in female youth soccer players.

METHODS

we conducted a cross-sectional study of young female soccer players (mean age: 13.6 ± 2.3 years). we asked about their history of musculoskeletal injuries using an electronic questionnaire. the proportion of young female soccer players with and without a history of soccer-related musculoskeletal injuries were compared based on physical characteristics, training attributes, position status (single vs. multiple), lower extremity strength, and joint laxity. a binary logistic regression analysis was used to generate, and adjusted odds ratios adjusted for potential co-variates (aor). a 95% confidence interval (95%ci) that did not cross one or p < 0.05 were considered statistically significant.

RESULTS

a total of 160 young female soccer players (mean age: 13.6 ± 2.3 years) participated in the study. an independent association was found between prior musculoskeletal injuries and older ages (aor: 1.60, 95%ci: 1.17, 2.20, p = 0.004), higher weight (aor: 1.10, 95%ci: 1.01, 1.20, p = 0.026), and greater bmi (aor: 1.43, 95%ci: 1.07, 1.90, p = 0.014).

CONCLUSIONS

musculoskeletal injuries were associated with age, weight, and bmi in female youth players. the current study indicates that maintaining proper body composition may be beneficial to reduce musculoskeletal injuries among female youth soccer players.

Exercise-Based Knee and Anterior Cruciate Ligament Injury Prevention

The Academy of Orthopaedic Physical Therapy and the American Academy of Sports Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This particular guideline focuses on the exercise-based prevention of knee injuries. J Orthop Sports Phys Ther. 2018;48(9):A1-A42. doi:10.2519/jospt.2018.0303.

Epidemiology of Recurrent Anterior Cruciate Ligament Injuries in National Collegiate Athletic Association Sports: The Injury Surveillance Program, 2004-2014

Background:

An anterior cruciate ligament (ACL) rupture is a serious injury that can be career-ending in collegiate athletics. A rerupture after primary ACL reconstruction occurs in 1% to 11% of all athletes.

Purpose:

To describe the epidemiology of recurrent ACL ruptures in the 25 National Collegiate Athletic Association (NCAA) sports in the NCAA Injury Surveillance Program (ISP) and to identify and compare sport-specific risk factors for a recurrent ACL rupture.

Study Design:

Descriptive epidemiology study.

Methods:

Athletes who experienced a primary or recurrent ACL rupture between 2004 and 2014 were identified using data from the NCAA ISP. ACL ruptures occurred in 12 of 25 sports during the study period. We assessed the rates and patterns of primary and recurrent ACL ruptures and reported them as events per 10,000 athlete-exposures (AEs). Sex-comparable sports were compared using rate ratios. Rupture rates were compared using odds ratios, with P values <.05 indicating significance. Regular-season and postseason data were combined because of low counts of postseason events.

Results:

Of 350,416 AEs, there were 1105 ACL ruptures, 126 of which were recurrent. The highest rates of recurrent ACL ruptures (per 10,000 AEs) were among male football players (15), female gymnasts (8.2), and female soccer players (5.2). Of sports played by athletes of both sexes, women’s soccer had a significantly higher rate of recurrent ACL ruptures than men’s soccer (rate ratio, 3.8 [95% CI, 1.3-15]). Among all sports, men had a significantly higher rate of recurrent ACL ruptures (4.3) than women (3.0) (P = .04). Overall, the ratio of recurrent to primary ACL ruptures decreased over the 10-year study period. Both women and men had a decreasing trend of recurrent to primary ACL ruptures, although women had a steeper decrease.

Conclusion:

These data can help identify athletes who are most at risk of recurrent ACL ruptures after ACL reconstruction and who may benefit from injury prevention programs.

MAXIMAL HIP AND KNEE MUSCLE STRENGTH ARE NOT RELATED TO NEUROMUSCULAR PRE-ACTIVITY DURING SIDECUTTING MANEUVER: A CROSS-SECTIONAL STUDY

BACKGROUND

Reduced lower extremity muscle strength as well as reduced lower extremity muscle pre-activity (defined as muscular activity just prior to initial ground contact) during high-risk movements are factors related to increased risk of non-contact ACL injury in adolescent female athletes. A strong relationship exists between muscle strength and muscle activity obtained during an isometric contraction, however, whether these two measures are related when muscle activity is obtained during a movement associated with a high risk of non-contact ACL injury is not known. Absence or presence of such a relationship may have implications for which training modalities to choose in the prevention of ACL injuries.

PURPOSE

The purpose of this study was to examine the relationship between maximal muscle strength of the hip extensors, hip abductors and knee flexors and the pre-activity of these muscle groups recorded during a sidecutting maneuver (high-risk movement) in adolescent female soccer and handball athletes.

STUDY DESIGN

Cross-sectional study.

METHODS

Eighty-five adolescent (age 16.9 ± 1.2 years) female elite handball and soccer athletes were assessed for maximal hip extensor, hip abductor and knee flexor muscle strength; and muscle pre-activity (electromyography recordings over a 10 ms time interval prior to foot ground contact) of the gluteus maximus (Gmax), gluteus medius (Gmed), biceps femoris (BF) and semitendinosus (ST) during a standardized sidecutting maneuver.

RESULTS

The results of the correlation analyses demonstrated poor and statistically non-significant correlations. Maximal hip extensor force (N/kg bw) and Gmax pre-activity [rs = 0.012 (95% CI -0.202 - 0.224), p = 0.91], maximal hip abductor force (N/kg bw) and Gmed pre-activity [rs = 0.171 (95% CI -0.044 - 0.371), p = 0.11], maximal knee flexor force (N/kg bw) and BF pre-activity [rs = 0.049 (95% CI -0.166 - 0.259), p = 0.65], and maximal knee flexor force and ST pre-activity [rs = 0.085 (95% CI -0.131 - 0.293), p = 0.44].

CONCLUSION

In the present exploratory study, the results imply that no relationship exists between maximal lower extremity isometric muscle strength and lower extremity muscle pre-activity during sidecutting. This means that athletes with low muscle strength may not necessarily demonstrate high (or low) muscle pre-activity during sidecutting - a well-known risk movement for sustaining non-contact ACL injury.

LEVELS OF EVIDENCE

Level 3.

A School-Based Neuromuscular Training Program and Sport-Related Injury Incidence: A Prospective Randomized Controlled Clinical Trial

CONTEXT

  An estimated 40 million school-aged children (age range = 5-18 years) participate annually in sports in the United States, generating approximately 4 million sport-related injuries and requiring 2.6 million emergency department visits at a cost of nearly $2 billion.

OBJECTIVE

  To determine the effects of a school-based neuromuscular training (NMT) program on sport-related injury incidence across 3 sports at the high school and middle school levels, focusing particularly on knee and ankle injuries.

DESIGN

  Randomized controlled clinical trial.

SETTING

  A total of 5 middle schools and 4 high schools in a single-county public school district.

PATIENTS OR OTHER PARTICIPANTS

  A total of 474 girls (222 middle school, 252 high school; age = 14.0 ± 1.7 years, height = 161.0 ± 8.1 cm, mass = 55.4 ± 12.2 kg) were cluster randomized to an NMT (CORE; n = 259 athletes) or sham (SHAM; n = 215 athletes) intervention group by team within each sport (basketball, soccer, and volleyball).

INTERVENTION(S)

  The CORE intervention consisted of exercises focused on the trunk and lower extremity, whereas the SHAM protocol consisted of resisted running using elastic bands. Each intervention was implemented at the start of the season and continued until the last competition. An athletic trainer evaluated athletes weekly for sport-related injuries. The coach recorded each athlete-exposure (AE), which was defined as 1 athlete participating in 1 coach-directed session (game or practice).

MAIN OUTCOME MEASURE(S)

  Injury rates were calculated overall, by sport, and by competition level. We also calculated rates of specific knee and ankle injuries. A mixed-model approach was used to account for multiple injuries per athlete.

RESULTS

  Overall, the CORE group reported 107 injuries (rate = 5.34 injuries/1000 AEs), and the SHAM group reported 134 injuries (rate = 8.54 injuries/1000 AEs; F_1,578 = 18.65, P < .001). Basketball (rate = 4.99 injuries/1000 AEs) and volleyball (rate = 5.74 injuries/1000 AEs) athletes in the CORE group demonstrated lower injury incidences than basketball (rate = 7.72 injuries/1000 AEs) and volleyball (rate = 11.63 injuries/1000 AEs; F_1,275 = 9.46, P = .002 and F_1,149 = 11.36, P = .001, respectively) athletes in the SHAM group. The CORE intervention appeared to have a greater protective effect on knee injuries at the middle school level (knee-injury incidence rate = 4.16 injuries/1000 AEs) than the SHAM intervention (knee-injury incidence rate = 7.04 injuries/1000 AEs; F_1,261 = 5.36, P = .02). We did not observe differences between groups for ankle injuries ( F_1,578 = 1.02, P = .31).

CONCLUSIONS

  Participation in an NMT intervention program resulted in a reduced injury incidence relative to participation in a SHAM intervention. This protective benefit of NMT was demonstrated at both the high school and middle school levels.

Exploring individual adaptations to an anterior cruciate ligament injury prevention programme

BACKGROUND

Individual responses to anterior cruciate ligament injury prevention programmes (ACL IPPs) have received little attention. This study examined the effects of an ACL IPP on neuromuscular control and lower limb biomechanics during landing at the group and individual levels.

METHODS

Sixteen female athletes were randomly allocated to training (n=8) or control (n=8) groups. Electromyography, and three-dimensional kinematic and kinetic data were collected during landing at two testing sessions. Repeated measures ANOVA and effect sizes (Cohen's d) examined the effect of the IPP at the group and individual levels. A sub-group analysis comparing the effect of the IPP on 'high-' (i.e. large peak knee abduction moment at baseline) versus 'low-risk' individuals was also conducted.

RESULTS

At the group level; the IPP increased activation of the medial hamstrings prior to landing (p<0.001; d=0.264) and the medial gastrocnemius at landing (p<0.001; d=0.426), and increased hip external rotation early after initial contact (p<0.001; d=0.476). Variable adaptations were seen across individuals within the training group for all variables (p<0.001). The IPP had a large effect in reducing frontal plane knee moments for 'high-risk' individuals (d>0.91), however these results did not reach statistical significance (p>0.05).

CONCLUSIONS

The IPP induced adaptations during landing, however, individual data revealed dissimilar responses to the programme. Individuals displaying a pre-existing high-risk strategy may incur greater benefits from IPPs, yet only if the programme targets the relevant high-risk strategy.

Osteoarthritis action alliance consensus opinion - best practice features of anterior cruciate ligament and lower limb injury prevention programs

AIM

To identify best practice features of an anterior cruciate ligament (ACL) and lower limb injury prevention programs (IPPs) to reduce osteoarthritis (OA).

METHODS

This consensus statement started with us performing a systematic literature search for all relevant articles from 1960 through January 2017 in PubMed, Web of Science and CINAHL. The search strategy combined the Medical Subject Heading (MeSH) and keywords for terms: (1) ACL OR “knee injury” OR “anterior cruciate ligament”; (2) “prevention and control” OR “risk reduction” OR “injury prevention” OR “neuromuscular training”; and (3) meta-analysis OR “systematic review” OR “cohort study” OR randomized. We found 166 different titles. The abstracts were reviewed for pertinent papers. The papers were reviewed by at least two authors and consensus of best practice for IPP to prevent OA was obtained by conference calls and e-mail discussions. All authors participated in the discussion.

RESULTS

The best practice features of an IPP have the following six components: (1) lower extremity and core strengthening; (2) plyometrics; (3) continual feedback to athletes regarding proper technique; (4) sufficient dosage; (5) minimal-to-no additional equipment; and (6) balance training to help prevent injuries. Exercises focused on preventing ankle sprains, hamstring injuries and lateral trunk movements are important. Plyometric exercises should focus on correcting knee valgus movement. Exercises should focus on optimizing the hamstring to quadriceps strength ratio. In order for IPP to be successful, there should be increased education and verbal feedback along with increased athletic compliance. Additional equipment is not necessary. Balance training alone does not significantly reduce injuries, but is beneficial with other exercises. Not enough evidence to recommend stretching and agility exercises, with no ill effects identified. Therefore, we suggest making these optional features.

CONCLUSION

Best practice features for ACL and lower limb IPPs to help prevent OA contain six key components along with two optional.

Prevention and Management of Post-operative Complications Following ACL Reconstruction

PURPOSE OF REVIEW

The goal of this paper is to review the current management and prevention of post-operative complications after anterior cruciate ligament (ACL) reconstruction. Trends in rehabilitation techniques will be presented, in addition to suggestions for interventions and expected milestones in ACL reconstruction recovery.

RECENT FINDINGS

ACL reconstruction protocols have evolved to more of a criterion-based progression rather than a tissue-healing time frame. Given the evolution of ACL surgical reconstruction techniques and rehabilitation protocols, the risk of post-operative complications can arise both early and late in the recovery process. This paper will discuss the role of preventative measures as it applies to the post-operative patient with ACL reconstruction. Short-term complications following ACL reconstruction include infection and deficits to knee motion and strength, whereas long-term complications include secondary ACL injury to either the involved or contralateral knee and lack of ability to return to high-level sports following this procedure. Future research should continue to address the multifactorial causes of secondary ACL injury and limited ability of patients to return to high level activities.

Prevention, treatment, and rehabilitation of anterior cruciate ligament injuries in children

As more children and adolescents participate in competitive organized sports, there has been an increase in the reported incidence of anterior cruciate ligament (ACL) injuries in these age groups. ACL injuries in skeletally immature athletes present a challenge, as reconstruction must preserve the physis of the distal femur and of the proximal tibia to avoid growth disturbances. Historically, a skeletally immature athlete with an ACL injury was treated with a brace and activity modification until skeletal maturity, with ACL reconstruction being performed at that time in the “non-copers” who experienced instability. More recently, evidence has shown that delayed reconstruction may lead to increased damage to the meniscus and articular cartilage. As a result, early reconstruction is favored to protect the meniscus and allow continued physical activity. While adolescents at or those near skeletal maturity may be treated with standard reconstruction techniques, they may result in growth disturbances in younger athletes with significant growth remaining. In response to the growing need for ACL reconstruction techniques in skeletally immature individuals, physeal-sparing and physeal-respecting reconstruction techniques have been developed. In addition to the advancements in surgical technique, ACL injury prevention has also gained attention. This growing interest in ACL prevention is in part related to the high risk of ACL re-tear, either of the ACL graft or of the contralateral ACL, in children and adolescents. Recent reports indicate that well-designed neuromuscular training programs may reduce the risk of primary and subsequent ACL injuries.

Reducing musculoskeletal injury and concussion risk in schoolboy rugby players with a pre-activity movement control exercise programme: a cluster randomised controlled trial

Background

Injury risk in youth rugby has received much attention, highlighting the importance of establishing evidence-based injury reduction strategies.

Aim

To determine the efficacy of a movement control exercise programme in reducing injuries in youth rugby players and to investigate the effect of programme dose on injury measures.

Methods

In a cluster-randomised controlled trial, 40 independent schools (118 teams, 3188 players aged 14–18 years) were allocated to receive either the intervention or a reference programme, both of which were to be delivered by school coaches. The intervention comprised balance training, whole-body resistance training, plyometric training, and controlled rehearsal of landing and cutting manoeuvres. Time-loss (>24 hours) injuries arising from school rugby matches were recorded by coaches and medical staff.

Results

441 time-loss match injuries (intervention, 233; control, 208) were reported across 15 938 match exposure-hours (intervention, 9083; control, 6855). Intention-to-treat results indicated unclear effects of trial arm on overall match injury incidence (rate ratio (RR)=0.85, 90% confidence limits 0.61 to 1.17), although clear reductions were evident in the intervention arm for concussion incidence (RR=0.71, 0.48 to 1.05). When trial arm comparisons were limited to teams who had completed three or more weekly programme sessions on average, clear reductions in overall match injury incidence (RR=0.28, 0.14 to 0.51) and concussion incidence (RR=0.41, 0.17 to 0.99) were noted in the intervention group.

Conclusion

A preventive movement control exercise programme can reduce match injury outcomes, including concussion, in schoolboy rugby players when compared with a standardised control exercise programme, although to realise the greatest effects players should complete the programme at least three times per week.

Visual Utilization During Postural Control in Anterior Cruciate Ligament- Deficient and -Reconstructed Patients: Systematic Reviews and Meta-Analyses

OBJECTIVE

To determine whether anterior cruciate ligament-deficient (ACL-D) individuals and individuals with a reconstructed anterior cruciate ligament (ACL-R) rely more heavily on visual information to maintain postural control.

DATA SOURCES

PubMed, CINAHL, and SPORTDiscus databases were searched from their earliest available date to May 24, 2016, using a combination of keywords.

STUDY SELECTION

Articles were included if they reported any instrumented static single-leg balance outcome in both a patient and control sample. The means and SDs of these outcomes must have been reported with both eyes open and eyes closed.

DATA EXTRACTION

Sample sizes, means, and SDs of single-leg balance measures for each group's eyes open and eyes closed testing conditions were extracted. The methodological quality of included studies was independently evaluated by multiple authors using an adapted version of the Quality Index.

DATA SYNTHESIS

Effect sizes were calculated by dividing the differences in change between eyes closed and eyes open in the ACL-D and control group and the ACL-R and control group by the pooled SD from the eyes closed trials for each analysis. Significant differences between the ACL-D and control group (effect size, -1.66; 95% confidence interval [CI], -2.90 to -.41) were noted. The ACL-R and control group were not different (effect size, -.61; 95% CI, -2.17 to .95).

CONCLUSIONS

ACL-D individuals but not individuals with ACL-R demonstrate a greater reliance on visual information during single-leg stance compared with healthy individuals.

Preventive Neuromuscular Training for Young Female Athletes: Comparison of Coach and Athlete Compliance Rates

CONTEXT

 Fewer athletic injuries and lower anterior cruciate ligament injury incidence rates were noted in studies of neuromuscular-training (NMT) interventions that had high compliance rates. However, several groups have demonstrated that preventive NMT interventions were limited by low compliance rates.

OBJECTIVE

 To descriptively analyze coach and athlete compliance with preventive NMT and compare the compliance between study arms as well as among school levels and sports.

DESIGN

 Randomized, controlled clinical trial.

SETTING

 Middle and high school athletic programs. Participants or Other Participants: A total of 52 teams, comprising 547 female athletes, were randomly assigned to the experimental or control group and followed for 1 athletic season.

INTERVENTION(S)

 The experimental group (n = 30 teams [301 athletes]: 12 basketball teams [125 athletes], 6 soccer teams [74 athletes], and 12 volleyball teams [102 athletes]) participated in an NMT program aimed at reducing traumatic knee injuries through a trunk-stabilization and hip-strengthening program. The control group (n = 22 teams [246 athletes]: 11 basketball teams [116 athletes], 5 soccer teams [68 athletes], and 6 volleyball teams [62 athletes]) performed a resistive rubber-band running program.

MAIN OUTCOME MEASURE(S)

 Compliance with the assigned intervention protocols (3 times per week during the preseason [mean = 3.4 weeks] and 2 times per week in-season [mean = 11.9 weeks] of coaches [coach compliance] and athletes [athlete compliance]) was measured descriptively. Using an independent t test, we compared coach and athlete compliance between the study arms. A 2-way analysis of variance was calculated to compare differences between coach and athlete compliance by school level (middle and high schools) and sport (basketball, soccer, and volleyball).

RESULTS

 The protocols were completed at a mean rate of 1.3 ± 1.1 times per week during the preseason and 1.2 ± 0.5 times per week in-season. A total of 88.4% of athletes completed 2/3 of the intervention sessions. Coach compliance was greater in the experimental group than in the control group (P = .014). Coach compliance did not differ by sport but was greater at the high school than the middle school (P = .001) level. Athlete compliance did not differ by study arm, sport, or school level.

CONCLUSIONS

 Athletes received instruction in about 50% of each protocol. Nearly 90% of athletes performed more than 2/3 of the assigned NMT interventions. The assigned intervention was performed more often in the experimental arm compared with the control arm. Coaches at the high school level complied with the given protocol more than middle school coaches did. Athletes complied well with the protocol, but coaches did not, especially at the middle school level.