Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 2: a review of prevention programs aimed to modify risk factors and to reduce injury rates

Prediction of ACL-tear by lower limbs muscle strength and flexibility: a prospective cohort study in 95 female soccer players

The aims of the study were to build models using logistic regression analysis of flexibility and strength tests to prospectively predict risk factors for anterior cruciate ligament tear (ACL-tear) in female soccer (FS) players, and to determine training cut-off for risk factors of the predictive model built. A prospective cohort study of 95 female players (aged 14-33 years) was conducted. Age, anthropometric data, soccer history, lower limb range of motion (ROM) and hip maximal isometric strength (MIS) were measured. At the prospective follow-up after 12 months, 7.4% of the players had developed an ACL-tear. The model showed a significant relationship (χ2(93) = 30.531, p < 0.001) between the ACL-tear and the predictor variables (leg length, HAD-NH [hip adduction] MIS, asymmetric ROM [ankle dorsiflexion with knee extended (AD-KE) and with knee flexed (AD-KF), and HE (hip extension)], hip ROM [HIR (internal rotation) and HAB (abduction)]). The Akaike Information Criteria (AIC) and Bayesian Information Criteria (BIC) for model fit were 30.24 and 51.79, respectively. The value R2 showed good model fit, 76.5% for Nagelkerke´s R2, 71.4% for McFadden´s R2 and 67.5% for Tjur´s R2. For the screening test, cut-off for leg length of ≥0.40 m, for HIR ROM of ≤44º and for asymmetry of HE ROM of ≥5° were set, which have an acceptable (AUC ≥ 0.755) discriminatory ability for the development of ACL-tear.

Effects of neuromuscular training on dynamic balance ability in athletes: A systematic review and meta-analysis

Objectives

This study aimed to quantitatively analyze the effects of neuromuscular training (NMT) on dynamic balance in healthy athletes through a systematic review and meta-analysis of randomized controlled trials.

Methods

Searches on six databases for randomized controlled trials examining the impact of NMT on athletes' balance ability. The search period extended from the inception of the database to March 16, 2024, languages are limited to Chinese and English. Review Manager 5.1 was used for literature quality assessment and data analysis. Stata 15.0 software was used for assessing publication bias, employing the clipping method, and conducting sensitivity analysis. The Grading of recommendations assessment development and evaluation (GRADE) was used to assess the certainty of evidence. Effect size (ES) was used to evaluate the impact effect of the results.

Results

(1) Meta-analysis: A total of 7 papers met the inclusion criteria, and the meta-analysis indicated that NMT had a positive impact on the dynamic balance ability of the right (SMD = 0.74) and left (SMD = 0.70) lower limb of athletes, and a statistically significant difference was observed (p < 0.01). Subgroup analysis revealed that NMT did not have a positive effect (p > 0.05) on the right anterior (SMD = 0.35); However, it had a positive effect (p < 0.05) on the right posteromedial (SMD = 1.22), right posterolateral (SMD = 0.82), right composite score (SMD = 0.79), left anterior (SMD = 0.38), left posteromedial (SMD = 1.19), left posterolateral (SMD = 0.57) and left composite score (SMD = 0.86). (2) Reporting bias: Funnel plot indicated evidence of publication bias, but there was no significant asymmetry in the funnel plot after trimming and filling. The results were not reversed, indicating the robustness of the combined results. (3) Sensitivity analysis: The results of the sensitivity analysis suggest that the data in this meta-analysis are relatively stable and credible. (4) Grading the evidence: Based on GRADE scale the certainty of evidence from the included studies was determined to be moderate.

Conclusion

Neuromuscular training can enhance the dynamic balance ability of athletes on both the left and right sides. Therefore, neuromuscular training is an effective method for enhancing the unilateral dynamic balance ability of athletes.

ACL Injury Etiology in Its Context: A Systems Thinking, Group Model Building Approach

Background/Objectives: Given the complex nature of Anterior Cruciate Ligament (ACL) injury, it is important to analyze its etiology with suitable approaches in order to formulate intervention strategies for effective prevention. The present study employs system thinking techniques to develop a Causal Loop Diagram (CLD) Model for investigating the risk factors for ACL Injury (CLD-ACLI), through a Group Model Building approach. Methods: A two-stage procedure was applied involving a comprehensive literature review followed by several systems thinking group-modeling co-creation workshops with stakeholders. Results: Based on input from experts and stakeholders, combined with the latest scientific findings, the derived CLD-ACLI model revealed a series of interesting complex nonlinear interrelationships causal loops between the likelihood of ACL injury and the number of risk factors. Particularly, the interaction among institutional, psychological, neurocognitive, neuromuscular, malalignment factors, and trauma history seem to affect neuromuscular control, which subsequently may alter the biomechanics of landing, predisposing the ACL to injury. Further, according to the proposed CLD-ACLI model, the risk for injury may increase further if specific environmental and anatomical factors affect the shear forces imposed on the ACL. Conclusions: The proposed CLD-ACLI model constitutes a rigorous useful conceptual presentation agreed upon among experts on the dynamic interactions among potential intrinsic and extrinsic risk factors for ACL injury. The presented causal loop model constitutes a vital step for developing a validated quantitative system dynamics simulation model for evaluating ACL injury-prevention strategies prior to implementation.

The Acute: Chronic Workload Ratio and Injury Risk in Semiprofessional Football Players

The purpose of this study was to analyze the association and predictive capacity between the acute:chronic workload ratio (ACWR) and non-contact injuries in a semiprofessional football team. Seventeen football or soccer players from a Spanish Third Division football team participated voluntarily in this study. A prospective longitudinal study was developed during the 2020/2021 season. Twenty-four weeks were analyzed from October to March, including a regenerative microcycle due to the absence of competition during Christmas. Rate of perceived exertion (RPE) and session-rate of perceived exertion (sRPE) were registered for every training and game session. Afterward, acute and chronic workloads were calculated, and ACWR was subsequently derived from them. Furthermore, non-contact injuries were registered during the period mentioned. The main findings were that there is a poor correlation between the ACWR and non-contact injuries (r=0.069 (p<0.05)), and the use of the ACWR by itself is insufficient to predict the occurrence of non-contact injuries in a semiprofessional football team. Consequently, the ACWR is not an useful predictive tool for injuries in semiprofessional football teams.

Factors Associated With Awareness, Adoption, and Implementation of Anterior Cruciate Ligament Injury Prevention in Youth Sports

BACKGROUND

Anterior cruciate ligament (ACL) injuries are among the most common injuries in adolescent athletes and result in significant financial and physical morbidity. Evidence-based programs designed to prevent ACL injury are effective. However, their adoption remains low. We sought to evaluate the awareness, evidence-based implementation, and barriers to implementation of ACL injury prevention programs (ACL-IPP) among youth athletic coaches.

HYPOTHESIS

Higher education level of the coach, higher level of training, number of teams coached, and coaching female teams would be associated with ACL-IPP implementation.

STUDY DESIGN

Cross-sectional survey.

LEVEL OF EVIDENCE

Level 4.

METHODS

We conducted an email survey sent to all 63 school districts within Section VI of the New York State Public High School Athletic Association. We employed descriptive statistics and tests of correlation to identify factors associated with ACL-IPP implementation.

RESULTS

A total of 73% of coaches said they were aware of ACL-IPP, and only 12% of coaches implemented ACL-IPP according to best evidence. Coaches of higher competitive levels were more likely to adopt ACL-IPP (P = 0.01), more likely to use them multiple times per week (P = 0.03), and for ≥1 seasons (P = 0.02). Coaches of multiple teams were more likely to adopt ACL-IPP (P = 0.01). There were no differences in evidence-based implementation of ACL-IPP with gender coached or level of education of the coach.

CONCLUSION

Overall awareness, adoption, and evidence-based implementation of ACL-IPP remain low. These results suggest that coaches at higher levels of play and multiple teams tend to use ACL-IPP more often. Gender coached and level of education do not appear to be associated with awareness or implementation.

CLINICAL RELEVANCE

Evidence-based ACL-IPP implementation remains low. Targeting coaches of younger athletes and fewer teams with local outreach programs and ACL-IPP may increase the implementation of ACL-IPP.

Exploring the Role of Sprint Biomechanics in Hamstring Strain Injuries: A Current Opinion on Existing Concepts and Evidence

Hamstring strain injuries are one of the most common injuries in sprint-based sports with the mechanism of injury considered the result of an interaction between applied mechanical strain and the capacity of the muscle to tolerate strain. To date, injury prevention and rehabilitation strategies have frequently focused on enhancing the capacity of the hamstrings to tolerate strain, with little consideration of factors directly influencing mechanical strain. Sprint running biomechanics are one factor proposed to influence the mechanical strain applied to the hamstrings that may be modified (towards reduced strain) within rehabilitation and injury prevention programs. This article aims to explore the theoretical mechanistic link between sprint running mechanics and hamstring strain injury, along with the available supporting evidence. In doing so, it hopes to provide practitioners with an understanding of mechanical parameters that may influence hamstring strain injury whilst also identifying areas for further research exploration.

Variables Associated With Knee Valgus in Male Professional Soccer Players During a Single-Leg Vertical Landing Task

Prior studies have explored the relationship between knee valgus and musculoskeletal variables to formulate injury prevention programs, primarily for females. Nonetheless, there is insufficient evidence pertaining to professional male soccer players. Here, the aim was to test the correlation of lateral trunk inclination, hip adduction, hip internal rotation, ankle dorsiflexion range of motion, and hip isometric strength with knee valgus during the single-leg vertical jump test. Twenty-four professional male soccer players performed a single-leg vertical hop test, hip strength assessments, and an ankle dorsiflexion range of motion test. A motion analysis system was employed for kinematic analysis. Maximal isometric hip strength and ankle dorsiflexion range of motion were tested using a handheld dynamometer and a digital inclinometer, respectively. The correlation of peak knee valgus with peak lateral trunk inclination was .43 during the landing phase (P = .04) and with peak hip internal rotation was -.68 (P < .001). For knee valgus angular displacement, only peak lateral trunk inclination presented a moderate positive correlation (r = .40, P = .05). This study showed that trunk and hip kinematics are associated with knee valgus, which could consequently lead to increased knee overload in male professional soccer players following a unilateral vertical landing test.

Anterior Cruciate Ligament Tears in the Adolescent Population: Injury Demographics and Risk of Reinjury Among High School Athletes

BACKGROUND

The incidence of anterior cruciate ligament (ACL) injuries is increasing among the adolescent population with a peak occurring in the high school age range.

PURPOSE

To characterize recent epidemiologic trends of ACL injuries, ACL reconstruction (ACLR), and retear rates in high school adolescents based on age, participating sport, and mechanism of injury.

STUDY DESIGN

Retrospective case series.

METHODS

A prospectively maintained institutional database was retrospectively reviewed for all patients 18 or younger who underwent primary ACLR between 2015 and 2020. Odds ratios were calculated for baseline patient characteristics and their association with risk of retear. Multivariate regression analysis was also performed to identify the relationship between retear and specific categorical variables.

RESULTS

A total of 482 patients were included, with a mean follow-up time of 13.0 ± 11.8 months. Patients were an average age of 16.1 ± 1.3 years old (range: 13 to 18 y). Initial presentation of ACL injuries in high school athletes often occurred at 16 years old regardless of the sport played. Based on age, high school freshmen and seniors are found to have an increased risk of ACL retear. One hundred three patients (21.6%) completed at least 2 or more years of follow-up after ACLR. Of these patients, 38.8% received a bone-tendon-bone (BTB) autograft, 36.9% hamstring autograft, 14.6% quadriceps tendon autograft, and 3.9% received hamstring allograft or other graft (eg, tibialis anterior and BTB allograft), respectively. There were 25 ipsilateral ACL retears that occurred in the patient cohort (5.2%). Thirteen (52%) of retears were females. Football and soccer were the most common sports played by patients with a retear of the ipsilateral knee (31.8% and 27.3%, respectively). Patients who were 13 to 14 or 18 years old ( P = 0.009 and 0.035, respectively) or who received a tibialis anterior/BTB allograft ( P = 0.002) were found to have increased risk of ACL retear compared with other age groups. When evaluating by sex, female soccer players had a greater risk of retear compared with male soccer players ( P = 0.007). When adjusting for multiple variables, (including age, sex, body mass index, primary reconstruction graft choice, sport, and length of follow-up), the odds of ipsilateral retear in patients who received hamstring autograft ( P = 0.02), sustained a contralateral ACL tear ( P = 0 .04), or a contact injury ( P = 0.01) were increased.

CONCLUSION

Initial presentation of ACL injuries in high school athletes often occurs at 16 years old regardless of the sport played. Based on age, high school freshmen and seniors are found to have an increased risk of ACL retear. However, the overall rate of ACL retear in high school athletes of all ages is low. Patients who underwent ACLR with hamstring tendon autograft had a greater risk of retear compared with other graft types. Female soccer players also had a greater risk of ACL retear. High school athletes must take caution when in the early high school years (underclassman) and more senior years (upperclassman), as susceptibility for ACL retears is elevated.

LEVEL OF EVIDENCE

Level IV.

Anterior cruciate ligament injuries in female athletes

The anterior cruciate ligament (ACL) is frequently injured in elite athletes, with females up to eight times more likely to suffer an ACL tear than males. Biomechanical and hormonal factors have been thoroughly investigated; however, there remain unknown factors that need investigation. The mechanism of injury differs between males and females, and anatomical differences contribute significantly to the increased risk in females. Hormonal factors, both endogenous and exogenous, play a role in ACL laxity and may modify the risk of injury. However, data are still limited, and research involving oral contraceptives is potentially associated with methodological and ethical problems. Such characteristics can also influence the outcome after ACL reconstruction, with higher failure rates in females linked to a smaller diameter of the graft, especially in athletes aged < 21 years. The addition of a lateral extra-articular tenodesis can improve the outcomes after ACL reconstruction and reduce the risk of failure, and it should be routinely considered in young elite athletes. Sex-specific environmental differences can also contribute to the increased risk of injury, with more limited access to and availablility of advanced training facilities for female athletes. In addition, football kits are designed for male players, and increased attention should be focused on improving the quality of pitches, as female leagues usually play the day after male leagues. The kit, including boots, the length of studs, and the footballs themselves, should be tailored to the needs and body shapes of female athletes. Specific physiotherapy programmes and training protocols have yielded remarkable results in reducing the risk of injury, and these should be extended to school-age athletes. Finally, psychological factors should not be overlooked, with females' greater fear of re-injury and lack of confidence in their knee compromising their return to sport after ACL injury. Both intrinsic and extrinsic factors should be recognized and addressed to optimize the training programmes which are designed to prevent injury, and improve our understanding of these injuries.

Impact of COVID-19 Era on the Anterior Cruciate Ligament Injury Rehabilitation: A Scoping Review

The surgical intervention rate and the subsequent rehabilitation plan for anterior cruciate ligament (ACL) injury was crucially affected by the COVID-19 pandemic due to the necessity in the face of the emergency. This review aimed to evaluate potential persistent and residual symptoms after COVID-19 disease, including fatigue and neuromuscular disorders. A scoping review design and methodology were used due to the exploratory nature of the research question, according to literature searches on PubMed/Medline, Scopus, Web of Science (WoS), and Physiotherapy Evidence Database (PEDro) electronic databases using the following keywords: "Anterior Cruciate Ligament", "ACL", "SARS-CoV-2", and "COVID-19". Undertraining and muscular knee imbalance might cause inefficient movement strategies, lack of knee stability, and increasing load with negative implications in ACL injuries. In the post-surgery period, during COVID-19, telerehabilitation approaches appeared to be successfully applied to maintain strength and range of motion in this condition. However, no definitive data are available regarding the most effective interventions. This scoping review showed the influence of the COVID-19 pandemic and associated restrictions on postoperative and rehabilitative care of ACL injuries.

The impact of the menstrual cycle on orthopaedic sports injuries in female athletes

There is a disparity in sport-related injuries between sexes, with females sustaining non-contact musculoskeletal injuries at a higher rate. Anterior cruciate ligament ruptures are between two and eight times more common than in males, and females also have a higher incidence of ankle sprains, patellofemoral pain, and bone stress injuries. The sequelae of such injuries can be devastating to an athlete, resulting in time out of sport, surgery, and the early onset of osteoarthritis. It is important to identify the causes of this disparity and introduce prevention programmes to reduce the incidence of these injuries. A natural difference reflects the effect of reproductive hormones in females, which have receptors in certain musculoskeletal tissues. Relaxin increases ligamentous laxity. Oestrogen decreases the synthesis of collagen and progesterone does the opposite. Insufficient diet and intensive training can lead to menstrual irregularities, which are common in female athletes and result in injury, whereas oral contraception may have a protective effect against certain injuries. It is important for coaches, physiotherapists, nutritionists, doctors, and athletes to be aware of these issues and to implement preventive measures. This annotation explores the relationship between the menstrual cycle and orthopaedic sports injuries in pre-menopausal females, and proposes recommendations to mitigate the risk of sustaining these injuries.

A Controlled Trial of the Effects of Neuromuscular Training on Physical Performance in Male and Female High School Athletes

BACKGROUND

Neuromuscular training (NMT) has demonstrated efficacy as an intervention to decrease the risk of anterior cruciate ligament injuries and improve sports performance. The effect of this training on the mechanisms that contribute to improved physical performance has not been well defined.

HYPOTHESIS

Athletes in the NMT group will have better mechanisms of fundamental movements and agility tests that may contribute to improved sports performance.

STUDY DESIGN

Prospective cohort study.

LEVEL OF EVIDENCE

Level 2.

METHODS

Eight high school teams (111 athletes, 53% male, mean age 16 years) participated, with half performing NMT. Physical performance was measured using the dorsaVi ViPerform system, a US Food and Drug Administration-cleared wireless sensor system. Agility was assessed using a timed 3-cone test. Independent sample t tests were used to compare differences between the intervention and control groups.

RESULTS

Matched pre- and postseason data were collected from 74 athletes after excluding athletes with injury and those lost to follow-up. Significant improvements were observed in the NMT group for loading/landing speed ratios during a single-leg hop test (right lower extremity = -0.19 [-0.37, 0.03], P = 0.03 and left lower extremity = -0.27 [-0.50, -0.03], P = 0.03). The control group had lower ground reaction forces compared with the NMT group (P < 0.02), while significant improvements were found in the NMT group for initial peak acceleration (P < 0.02) and cadence (P = 0.01) during a straight-line acceleration/deceleration test. For the 3-cone agility test, the postseason time decreased compared with preseason in the NMT group, whereas the time for the control group increased (-0.37 s vs 0.14 s, P < 0.00).

CONCLUSION

The results demonstrate that NMT administered by sports medicine clinicians can significantly improve some physical performance of fundamental movements in high school athletes.

CLINICAL RELEVANCE

Coaches should be trained to effectively deliver NMT in order to improve sports performance.

A scoping review of portable sensing for out-of-lab anterior cruciate ligament injury prevention and rehabilitation

Anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) surgery are common. Laboratory-based biomechanical assessment can evaluate ACL injury risk and rehabilitation progress after ACLR; however, lab-based measurements are expensive and inaccessible to most people. Portable sensors such as wearables and cameras can be deployed during sporting activities, in clinics, and in patient homes. Although many portable sensing approaches have demonstrated promising results during various assessments related to ACL injury, they have not yet been widely adopted as tools for out-of-lab assessment. The purpose of this review is to summarize research on out-of-lab portable sensing applied to ACL and ACLR and offer our perspectives on new opportunities for future research and development. We identified 49 original research articles on out-of-lab ACL-related assessment; the most common sensing modalities were inertial measurement units, depth cameras, and RGB cameras. The studies combined portable sensors with direct feature extraction, physics-based modeling, or machine learning to estimate a range of biomechanical parameters (e.g., knee kinematics and kinetics) during jump-landing tasks, cutting, squats, and gait. Many of the reviewed studies depict proof-of-concept methods for potential future clinical applications including ACL injury risk screening, injury prevention training, and rehabilitation assessment. By synthesizing these results, we describe important opportunities that exist for clinical validation of existing approaches, using sophisticated modeling techniques, standardization of data collection, and creation of large benchmark datasets. If successful, these advances will enable widespread use of portable-sensing approaches to identify ACL injury risk factors, mitigate high-risk movements prior to injury, and optimize rehabilitation paradigms.

Influence of Strength Training Variables on Neuromuscular and Morphological Adaptations in Prepubertal Children: A Systematic Review

Strength training in prepubertal children is one of the topics that has aroused the most interest and controversy among training professionals in recent years. Therefore, the aim of the present study was to analyze the available scientific evidence on the influence of strength training variables on morphological and/or neuromuscular adaptations in healthy prepubertal populations with no previous experience in this type of training according to the descriptive sample characteristics. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis, 22 studies were selected after a systematic search and selection process using four electronic databases: Google Scholar, PubMed, Scopus, and SPORT Discus. Furthermore, the internal validity of the studies included was assessed using the modified PEDro scale. The sample consisted of 604 prepubertal children (age, 10.02 ± 0.75 years), of whom 473 were boys and 131 were girls, with 104 strength training programs recorded. Strength training resulted in a significant increase in jumping (n = 29) and sprinting (n = 13) abilities. Moreover, muscle strength was increased in 100% of the cases. Morphologically, strength training resulted in a decrease in body fat percentage (n = 19) and an increase in lean body mass (n = 17). With regard to gender, increases in general sport skills and basic physical abilities were significant in males but not in females. Thus, the results are more heterogeneous in girls due to the small number of studies carried out. Therefore, this research provides practical applications for coaches to design and implement more effective training programs to maximize adaptations, enhance physical performance, and reduce injury risk.

Epidemiology of Hand and Wrist Injuries in Collegiate-Level Athletes in the United States

PURPOSE

Hand and wrist injuries are common among competitive athletes and can have a substantial impact on playing time and future participation. The purpose of this study was to provide epidemiological data from the National Collegiate Athletic Association Injury Surveillance Program to correlate injury diagnosis with the need for surgery and time loss.

METHODS

Using the National Collegiate Athletic Association Injury Surveillance Program, this retrospective study extracted data of hand and wrist injuries for all 25 National Collegiate Athletic Association sports from the academic years 2004-2005 to 2013-2014. The "severe" category was defined as injuries resulting in the following: (1) surgery, (2) season-ending status, or (3) more than 30 days of playing time loss. The epidemiologic data included injury rate per 100,000 athlete exposures (defined as 1 athlete participating in 1 practice or competition) based on diagnoses and demographic information such as sports and sex. We used a Poisson regression model to estimate the incidence rate and 95% confidence interval.

RESULTS

Overall, 4,851 hand injuries were identified, with an injury rate of 41.2 per 100,000 athlete exposures. The most common diagnoses were metacarpal or phalangeal fractures (19.9%), lacerations or contusions (15.4%), and wrist sprains (14.7%). The surgical rate was 9.6%, and the season-ending rate was 5.8%. Severe injuries occurred in 17.5% of the hand and wrist injuries; within this subset, the most common diagnoses included metacarpal or phalangeal fractures (43.8%), scaphoid fractures (12.8%), and thumb ulnar collateral ligament tears (8.7%). Scaphoid fractures and metacarpal or phalangeal fractures had the highest surgical rate and season-ending rate among all the injuries.

CONCLUSIONS

The injury rate of hand and wrist injuries is comparable with those of other common sports injuries. Approximately one fifth of the injuries were considered severe, which led to a high surgical rate, and these had a considerable impact on the athletes' ability to finish the season.

TYPE OF STUDY/LEVEL OF EVIDENCE

Outcome research level II.

Evidence Review for Preventing Osteoarthritis After an Anterior Cruciate Ligament Injury: An Osteoarthritis Action Alliance Consensus Statement

CONTEXT

The Osteoarthritis Action Alliance formed a secondary prevention task group to develop a consensus on secondary prevention recommendations to reduce the risk of osteoarthritis after a knee injury.

OBJECTIVE

Our goal was to provide clinicians with secondary prevention recommendations that are intended to reduce the risk of osteoarthritis after a person has sustained an anterior cruciate ligament injury. Specifically, this manuscript describes our methods, literature reviews, and dissenting opinions to elaborate on the rationale for our recommendations and to identify critical gaps.

DESIGN

Consensus process.

SETTING

Virtual video conference calls and online voting.

PATIENTS OR OTHER PARTICIPANTS

The Secondary Prevention Task Group consisted of 29 members from various clinical backgrounds.

MAIN OUTCOME MEASURE(S)

The group initially convened online in August 2020 to discuss the target population, goals, and key topics. After a second call, the task group divided into 9 subgroups to draft the recommendations and supportive text for crucial content areas. Twenty-one members completed 2 rounds of voting and revising the recommendations and supportive text between February and April 2021. A virtual meeting was held to review the wording of the recommendations and obtain final votes. We defined consensus as >80% of voting members supporting a proposed recommendation.

RESULTS

The group achieved consensus on 15 of 16 recommendations. The recommendations address patient education, exercise and rehabilitation, psychological skills training, graded-exposure therapy, cognitive-behavioral counseling (lacked consensus), outcomes to monitor, secondary injury prevention, system-level social support, leveraging technology, and coordinated care models.

CONCLUSIONS

This consensus statement reflects information synthesized from an interdisciplinary group of experts based on the best available evidence from the literature or personal experience. We hope this document raises awareness among clinicians and researchers to take steps to mitigate the risk of osteoarthritis after an anterior cruciate ligament injury.

Focus of Attention During ACL Injury Prevention Exercises Affects Improvements in Jump-Landing Kinematics in Soccer Players: A Randomized Controlled Trial

ABSTRACT

Dalvandpour, N, Zareei, M, Abbasi, H, Abdoli, B, Mohammadian, MA, Rommers, N, and Rössler, R. Focus of attention during ACL injury prevention exercises affects improvements in jump-landing kinematics in soccer players: a randomized controlled trial. J Strength Cond Res 37(2): 337-342, 2023-Anterior cruciate ligament tears are severe and complex knee injuries that commonly occur in soccer. Prevent injuries enhance performance (PEP) is an exercise-based prevention program to effectively reduce anterior cruciate ligament injuries. It is, however, unclear how the delivery of the program contributes to its effectiveness. Therefore, we aimed to investigate the effect of the focus of attention that was emphasized during the delivery of the PEP program on jump-landing kinematics in male, elite-level, U21 soccer players. Forty-two players participated in this randomized controlled trial and were allocated to (a) the internal focus of attention (IF) group, receiving instructions focusing on the execution of the exercise (b), the external focus of attention (EF) group, receiving instructions focusing on the outcome of the exercise, or (c) the control group. Before and after the 8-week intervention, players performed a jump-landing task during which we measured hip and knee angles at the initial contact, peak knee flexion, and peak vertical ground reaction force using a 3-dimensional motion analyzer. A repeated-measures analysis of variance was used to compare groups over time. Significant time-by-group interaction effects with large effect sizes were found for hip flexion at all moments (p < 0.032; η2 > 0.15) and for the knee flexion angle at initial contact and maximum knee flexion (p < 0.001; η2 > 0.35), all in favor of the EF group. This shows that EF during PEP improves hip and knee joint kinematics in the sagittal plane more than IF. Therefore, EF during PEP instructions is preferred to increase the effectiveness of this injury prevention program.

Injury prevention programs including balance exercises with compliance and follow-up reduce the incidence of knee injuries in athletes: A systematic review and meta-analysis

BACKGROUND: The knee is one of the most common injuries in sports. However, the incidence of knee injuries can be decreased by enhancing balance and neuromuscular control. OBJECTIVE: The aim of this systematic review and meta-analysis was to investigate how injury prevention programs (IPPs) that include balance training influence knee injury rates in athletes. METHODS: Data were obtained from different databases (1985–2021). Only randomised controlled trials that used IPPs that include balance training, were considered. Two investigators extracted data from the qualifying documents. The critical outcome data elements derived from the included studies were the number of ACL/knee injuries, ACL/knee injury rates, exposure hours, compliance rate, and follow-up duration. RESULTS: Compared to the control groups, those who participated in the IPP had a 54% lower risk of knee injuries per 1000 hours of exposure (IRR 0.457 (95% CI 0.346–0.603), P= 0.001) and a 60% lower risk of ACL injuries per 1000 hours of exposure (IRR 0.401 (95% CI 0.215–0.750), P= 0.004). CONCLUSIONS: IPPs that include balance training may reduce the risk of knee injuries.

Qualitative and Quantitative Assessment of the Medial Patellar Retinaculum Anatomy: the Anteromedial Side of the Knee Revisited

BACKGROUND

In the current literature, studies on the anatomy of the anteromedial region of the knee are scarce. However, the anteromedial structures, especially the longitudinal medial patellar retinaculum (MPR), may play an important role in restraining external tibial rotation.

PURPOSE

To conduct a layer-by-layer dissection of the anteromedial side of the knee and describe qualitatively and quantitatively the MPR anatomy pertaining to surgically relevant landmarks.

STUDY DESIGN

Descriptive laboratory study.

METHODS

A total of 10 fresh-frozen human cadaveric knees (mean age 81 ± 16.3 years) without history of previous ligament injury were used in this study. A layer-by-layer dissection was performed, and measurements were obtained using a tactile 3-dimensional (3-D) measuring arm to define the anatomy of the MPR in relation to surgically relevant landmarks, such as the superficial medial collateral ligament (sMCL) and medial patellofemoral ligament (MPFL). The 3-D datasets were used for multiplanar reconstruction.

RESULTS

The tibial and femoral attachment of the MPR were identified in 100% of cases. Layer-by-layer dissection confirmed its close topography to the sMCL. The mean length of the MPR was 84.9 ± 9.1 mm. The average width of the tibial and femoral attachment was 23.8 ± 3.1 mm and 69.2 ± 8.2 mm, respectively. The distance from the midpoint of the MPR tibial attachment to the midpoint of the distal tibial attachment of the sMCL was 27.2 ± 5.8 mm. Femorally, the MPR attached at the anterior border of the MPFL over a mean distance of 52.3 ± 9.4 mm.

CONCLUSION

The MPR is a distinct tibiofemoral structure with well-defined tibial and femoral attachments, which could be consistently identified. Layer-by-layer dissection confirmed its close topography to the sMCL and MPFL.

CLINICAL RELEVANCE

As injuries to the anteromedial side of the knee may contribute to anteromedial rotational rotatory instability (AMRI), precise knowledge of the underlying anatomy of the MPR may be necessary to perform an anatomic reconstruction of the anteromedial side of the knee.

Dynamic knee valgus prevalence in children and its association with pain intensity, foot mobility, and sex- A cross-sectional study

Introduction

Knee pain can impact the performance of activities and sports participation in children. Dynamic knee valgus is a movement pattern commonly related to health conditions that may be associated with sex and foot kinematics in children.

Objective

To assess the prevalence of dynamic knee valgus and its relationship with foot mobility, sex, and knee pain in children.

Method

A cross-sectional observational study was carried out with 144 children (10-18 years old). The pain level was investigated using the Visual Analog Pain Scale and categorized into no pain/minor pain (≤2 cm), moderate pain (3-4,9 cm), and severe pain (≥5.0 cm). Foot mobility was assessed using the adapted navicular drop test and categorized into poor/adequate foot mobility (0.0 cm-0.9 cm) and greater foot mobility (≥1.0 cm). The dynamic knee valgus presence was checked using the step-down test. The association analysis was performed using simple tabulation considering the cluster effect. The Prevalence Ratios and the respective confidence intervals (95%) were estimated from Multiple Poisson Regression with robust variance. A significance level of 5% was adopted.

Results

The dynamic knee valgus prevalence was 26.3% and 26.9% in the right and left lower limbs, respectively. Females presented greater dynamic knee valgus frequency in the left lower limb than males. The dynamic knee valgus presence in males was associated with foot mobility in right (p = 0.001) (Prevalence Ratio: 9.33 Confidence Interval: 2.93-29.72) and left lower limbs (p = 0.003) (Prevalence Ratio: 6.25 Confidence Interval: 1.7-22.62).

Conclusion

Male and female children showed different relationships of the analyzed factors, suggesting that characteristics related to sex may impact the aspects linked to dynamic knee in children.

Injury prevention programs that include plyometric exercises reduce the incidence of anterior cruciate ligament injury: a systematic review of cluster randomised trials

QUESTION

Do injury prevention programs that include plyometric exercises reduce the incidence of anterior cruciate ligament (ACL) injuries in sport?

DESIGN

Systematic review of (cluster) randomised trials with meta-analysis.

PARTICIPANTS

Sporting participants of any age, sex or competition level.

INTERVENTIONS

The experimental intervention was an injury prevention program that included plyometric exercises. The control intervention was the usual warm-up program, which did not include plyometric exercises.

OUTCOME MEASURES

Exposure-based ACL injury rates.

RESULTS

The initial search yielded 7,302 articles, of which nine met the inclusion criteria. All nine articles reported cluster randomised trials, providing data on 14,394 participants. The pooled results showed that injury prevention programs that include plyometric exercises reduce the risk of ACL injury by 60% per 1,000 hours of exposure compared with the control group, with an injury risk ratio (IRR) of 0.40 (95% CI 0.26 to 0.63). Data from subgroups of these trials estimated that this preventative effect may be stronger in males (IRR 0.21, 95% CI 0.07 to 0.62) and weaker in females (IRR 0.51, 95% CI 0.30 to 0.87), albeit with less precise estimates. Subgroup analysis also suggested a stronger effect on non-contact ACL injuries (IRR 0.34, 95% CI 0.18 to 0.65), whereas the effect on contact ACL injuries remained uncertain (IRR 0.59, 95% CI 0.15 to 2.30).

CONCLUSIONS

Injury prevention programs that incorporate plyometric exercises substantially decrease the risk of ACL injuries more than warm-up programs that do not include plyometric exercises. The preventive effect appears to be stronger among males and in the prevention of ACL injuries that do not involve contact with another player. PROSPERO CRD42020196982.

Factors influencing performance and injury risk in elite female Gaelic team sport players and future research directions: a narrative review

BACKGROUND

Sports science research in elite female Gaelic team sports has increased in recent years, but still a large disparity exists between the volume of studies involving male and female players. As a consequence of this, it is difficult for practitioners to develop an evidence-based approach when working with female players.

MAIN BODY

In this review, we discuss the current research available in elite female Gaelic team sports with focus on seven specific areas including physical and physiological demands, anthropometric and performance characteristics, injury risk, nutritional considerations, and female physiology. There appears to be unique physical demands data in match play across positions in Camogie, however, there is currently no comparative data available in ladies Gaelic football. Similarly, there is no research available on the physiological demands of both elite female Gaelic team sports. According to existing literature, performance characteristics such as speed and power are lower in this population compared to other elite female team sports. Although data is limited, the anthropometric characteristics of elite female Gaelic team sport players appear homogenous with some positional differences observed at a sub-elite level. Previous research has demonstrated a high prevalence of lower limb injuries in female elite Gaelic team sports and the provision of quality, evidence-based strength & conditioning could help mitigate these injury risks. Female Gaelic team sport players have been shown to have poor nutrition knowledge and inadequate intakes of micronutrients. Finally, although menstrual cycle phase and oral contraceptives have been shown to influence performance in other female intermittent sports, to date there has not been any research carried out in elite female Gaelic team sport players.

CONCLUSIONS

It is evident that limited research has been carried out on elite female Gaelic sport players. More up-to-date, high-quality investigations are needed to address the research gaps, which in turn should enable practitioners in the field to apply sound, evidence-based practice/theory when working with this population.

Pre-operative knee extensor and flexor torque after secondary ACL rupture: a comparative retrospective analysis

Background

Secondary anterior cruciate ligament (ACL) ruptures are a relevant clinical concern after surgical treatment of a primary ACL rupture. However, there is a lack of scientific evidence related to the role of muscle strength prior to revision surgery in a second ACL rupture. The aim of this study was to assess differences in knee extensor and flexor strength in patients before primary and secondary ACL reconstruction compared to healthy controls.

Methods

In total, n = 69 age, weight and sex matched individuals were included in the study: n = 23 patients with isolated primary ACL rupture, n = 23 with secondary ACL rupture, and n = 23 matched healthy controls. Maximal isokinetic knee extension and flexion torque normalized to body mass was assessed for both legs.

Results

For patients with secondary ACL ruptures, torques were reduced in the non-injured (extension: 1.94 Nm/kg vs. 2.46 Nm/kg, p < 0.05, flexion: 1.25 Nm/kg vs. 1.59 Nm/kg, p < 0.05) and the injured leg (extension: 1.70 Nm/kg vs. 2.46 Nm/kg, p < 0.05, flexion: 1.14 Nm/kg vs. 1.59 Nm/kg, p < 0.05) compared to healthy controls. For patients with a primary ACL rupture torques were reduced in the non-injured (extension: 1.92 Nm/kg vs. 2.46 Nm/kg, p < 0.05, flexion: 1.24 Nm/kg vs. 1.59 Nm/kg, p < 0.05) and the injured leg (extension: 1.38 Nm/kg vs. 2.46 Nm/kg, p < 0.05, flexion: 1.01 Nm/kg vs. 1.59 Nm/kg, p < 0.05) compared to healthy controls. There were no differences between patients with primary and secondary ruptures, except of the knee extension on the injured leg showing higher values after a secondary ACL rupture (1.38 Nm/kg vs. 1.70 Nm/kg, p < 0.05).

Conclusions

The findings indicate that maximal knee torques were significantly reduced in patients with primary and secondary ACL ruptures before surgical reconstruction for the non-injured and injured leg as compared to healthy controls. Further investigations are needed to assess strength abilities before and after a second revision within a prospective design.

Prevention of Non-Contact Anterior Cruciate Ligament Injuries among Youth Female Athletes: An Umbrella Review

Anterior cruciate ligament (ACL) injuries account for a large percentage of knee injuries, disproportionately affecting female athletes. To help health professionals stay current, we performed an umbrella review to evaluate the effectiveness of ACL injury prevention programs in reducing non-contact ACL injury rates, determine the effective components within interventions, and provide clinical recommendations. Twelve databases (Medline, Embase, Cochrane Database of Systematic Reviews, SPORTDiscus, Cumulative Index to Nursing and Allied Health Literature, PEDro, Web of Science Core Collection, Epistemonikos, TRIP, BC Guidelines and Protocols, CPG Infobase, ProQuest Dissertations and Theses Global) were searched in May 2021 to identify relevant systematic reviews and meta-analyses. Four databases were searched again in September 2021 to identify recent primary literature. Non-contact ACL injury data were extracted to calculate incidence rate ratios (IRRs) and these were combined using an inverse variance random-effects model. A qualitative assessment of included reviews was performed. The methodological quality of the studies was assessed using a Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2) or Cochrane Risk-of-Bias Tool for Randomized Trials (RoB 2). Sixteen reviews and two primary studies met the inclusion criteria. Across 11 primary studies, prevention programs were effective in reducing non-contact ACL injuries by 64% (IRR = 0.36 (95% CI: 0.18-0.70)). A multi-faceted exercise program, beginning in the pre-season and containing at least three exercise types, may be beneficial in reducing ACL injury risk.

Minimizing the risk of graft failure after anterior cruciate ligament reconstruction in athletes. A narrative review of the current evidence

Anterior cruciate ligament (ACL) tear is one of the most common sport-related injuries and the request for ACL reconstructions is increasing nowadays. Unfortunately, ACL graft failures are reported in up to 34.2% in athletes, representing a traumatic and career-threatening event. It can be convenient to understand the various risk factors for ACL failure, in order to properly inform the patients about the expected outcomes and to minimize the chance of poor results. In literature, a multitude of studies have been performed on the failure risks after ACL reconstruction, but the huge amount of data may generate much confusion.The aim of this review is to resume the data collected from literature on the risk of graft failure after ACL reconstruction in athletes, focusing on the following three key points: individuate the predisposing factors to ACL reconstruction failure, analyze surgical aspects which may have significant impact on outcomes, highlight the current criteria regarding safe return to sport after ACL reconstruction.

Single-joint Hybrid Assistive Limb in Knee Rehabilitation after ACL Reconstruction: An Open-label Feasibility and Safety Trial

Objectives:

Methods:

Results:

Conclusions:

ACL injury prevention: Where have we come from and where are we going?

Anterior cruciate ligament (ACL) injuries are one of the most common and severe knee injuries across sports. As such, ACL injury prevention has been a focus of research and sports medicine practice for the past three-plus decades. Examining the current research and identifying both clinical strategies and research gaps, the aim of this review is to empower clinicians and researchers with knowledge of where the ACL injury prevention literature is currently and where it is going in the future. This paper examines the mechanism of ACL injury prevention, screening, implementation, compliance, adherence, coronavirus, and areas of future research. Clinical significance: The time lag between research and practical implementation in general healthcare settings can be as long as 17 years; however, athletes playing sports today are unable to wait that long. With effective programs already established, implementation and adherence to these programs is essential. Strategies such as coaching education, increasing awareness of free programs, identifying barriers, and overcoming implementation obstacles through creative collaboration are just a few ways that could help improve both ACL injury prevention implementation and adherence.

The Role of the Results of Functional Tests and Psychological Factors on Prediction of Injuries in Adolescent Female Football Players

Football is a popular sport among adolescent females. Given the rate of injuries in female footballers, identifying factors that can predict injuries are important. These injuries are often caused by complex reasons. The aim of this study was to investigate if the combination of demographic (age, number of training and match play hours/week), psychosocial (perceived stress, adaptive coping strategies) and physiological factors (functional performance) can predict a traumatic injury in adolescent female footballers. A cohort consisting of 419 female football players aged 13-16 years was established. Baseline questionnaires covered potential risk factors for sport injuries, and measurements included football-related functional performance tests. Data were collected prospectively with a weekly online questionnaire for 52 weeks covering, e.g., injuries, training, and match play hours/week. A total of 62% of the players reported at least one traumatic injury during the 52 weeks. The coping strategy "positive reframing" had the strongest association with the risk of traumatic injuries. The combination of more frequent use of the coping strategy, positive reframing, and high levels of physical performance capacity may prevent a traumatic injury in adolescent female footballers. Coaches are encouraged to adopt both physiological and psychological factors when preventing injuries in young female footballers.

Acute Effects of Salvia Supplementation on Cognitive Function in Athletes During a Fatiguing Cycling Exercise: A Randomized Cross-Over, Placebo-Controlled, and Double-Blind Study

Background:Salvia (sage) supplementation has been shown to improve the cognition function in healthy individuals or patients (e.g., attention, memory). To date, no study has explored its relevancy in the context of sporting performance. The aim of this study was to explore the acute effects of a combination of Salvia officinalis and Salvia lavandulaefolia on cognitive function in athletes performing a fatiguing cycling task.

Methods: Twenty-six volunteers were included in this cross-over, randomized, double-bind vs. placebo trial. Two hours before the two experimental sessions (here called SAGE and PLACEBO), volunteers randomly received a supplementation of sage or placebo. During each experimental session, participants were tested at four occasions while cycling during a warm-up, in the middle and at the end of a fatiguing task and after a short 5-min recovery. Tests included a Stroop task, a simple reaction time task, and a backward digit span memory task. Heart rate and rating of perceived exertion (RPE) were also measured at the beginning of the four test sessions.

Results: Heart rate was significantly greater during the fatiguing exercise than during warm-up and recovery (P < 0.001) without any supplementation effect. RPE was greater during the fatiguing exercise than during warm-up and recovery (P < 0.001). Moreover, RPE was significantly lower during the SAGE session as compared to PLACEBO (P = 0.002). Reaction time was not altered during the exercise but was significantly shorter with SAGE as compared to PLACEBO (P = 0.023). The Stroop task only revealed significantly longer reaction time during warm-up as compared to recovery (P = 0.02) independently of the supplementation. The digit span memory test revealed a significant greater span score with SAGE as compared to PLACEBO (P = 0.044).

Conclusion: The combination of Salvia improved the cognitive functions (perceived exertion, working memory, and reaction time). The positive effects were obtained in fresh condition and were maintained with fatigue.

Medio-Lateral Hamstring Muscle Activity in Unilateral vs. Bilateral Strength Exercises in Female Team Handball Players - A Cross-Sectional Study

BACKGROUND

Reduced activation of the hamstring muscles and specifically the medial semitendinosus muscle (ST) has been shown to be a risk factor for non-contact anterior cruciate ligament (ACL) injury. Specific hamstring strength exercises may show high ST activity, however the effect of unilateral vs. bilateral exercise execution on ST activation remains unknown.

PURPOSE

To investigate selected lower limb strengthening exercises performed either unilaterally or bilaterally to identify 1) which exercise elicited the highest hamstring activation, 2) which exercise elicited the highest ST activation, and 3) to examine if unilateral exercise execution altered the medio-lateral hamstring activation pattern. Furthermore, the kinematic characteristics of each specific exercise and execution modality were determined to reveal possible causes for differences in medio-lateral hamstring activation between the different exercise conditions.

STUDY DESIGN

Cross-sectional study.

METHODS

Single-session repeated measures were obtained in a randomized manner. Twenty-three female elite team handball players were recruited. Hamstring electromyographic (EMG) activity and 3D kinematics were obtained during selected lower limb exercises (hip thrust, kettlebell swing, Romanian deadlift). Hamstring EMG activity, normalized to maximal voluntary contraction (MVC) (nEMG), and inter-muscular activation difference between the ST and lateral hamstring biceps femoris (BF) were compared across exercises using two-way repeated measures ANOVA.

RESULTS

Bilateral hip thrust demonstrated highest overall hamstring activity (68.9±16.6 %). Kettlebell swing (Δ13%-point, p<0.01) and Romanian deadlift (Δ20-24%-point, p<0.01) demonstrated greater ST-BF activation differences (Δ=ST-BF) in favor of ST compared to hip thrust (Δ2-7%). Positive correlations were observed between knee joint angle and ST activity in kettlebell swing and deadlift.

CONCLUSION

Kettlebell swing, deadlift and hip thrust all produced high activation of the hamstring muscles. Kettlebell swing and both deadlift exercises were superior in activating ST over BF, favoring these exercises in the prevention of non-contact ACL injury in female athletes, which should be evaluated in future intervention studies.

LEVEL OF EVIDENCE

3.

Injury risk profile of amateur Irish women soccer players and players' opinions on risk factors and prevention strategies

OBJECTIVE

To explore injury profile, opinions on risk factors and injury prevention, among Irish amateur women soccer players.

DESIGN

A cross-sectional online survey.

SETTING

Irish amateur winter league.

PARTICIPANTS

Active players ≤18 years of age.

MAIN OUTCOMES

Differences were found between injured and uninjured groups, and risk factors that significantly predict soccer injury were identified.

RESULTS

168 injuries were reported by 83 respondents during the winter season. An increased prevalence of competition anxiety was observed in (53.8%:n = 85 of respondents) compared to other risk factors. There was a negative association between injuries and players' general health state (OR = 0.820, 95% CI 0.7-0.9, p = 0.007). Players' knowledge about some risk factors including playing position, joint hypermobility, and playing during menses contradicts current evidence. 50%; n = 67 of the respondents had not received any education on injury risk or prevention.

CONCLUSION

This study identified that Irish amateur women soccer players that responded have different characteristics, prevalence of risk factors and injury profiles to women players from different levels and countries. The findings suggest that some players may not be aware of the existing evidence base pertaining to common risk factors for injury. Further research is required to confirm the findings and explore the implementation of injury prevention strategies.

Clinical Risk Profile for a Second Anterior Cruciate Ligament Injury in Female Soccer Players After Anterior Cruciate Ligament Reconstruction

BACKGROUND

The risk of a second anterior cruciate ligament (ACL) injury when participating in pivoting sports after ACL reconstruction is high. Risk factors associated with a second ACL injury are complex.

PURPOSE

To investigate the combinations of various clinical risk factors associated with second ACL injury in female soccer players with a primary unilateral ACL reconstruction, using Classification and Regression Tree (CART) analysis.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 117 active female soccer players (mean ± SD age, 20 ± 2 years) were included. Athletes were enrolled 19 ± 9 months after ACL reconstruction and were prospectively followed for 2 years. At baseline, all players underwent assessment of knee and ankle joint range of motion (ROM), participated in functional tests (postural control, hop performance, and movement asymmetries in the lower limbs and trunk), and answered questionnaires (patient-reported knee function, knee-related quality of life, psychological and personality factors). A clinical prediction model using CART was developed.

RESULTS

A total of 28 players (24%) sustained a second ACL injury (21 ipsilateral and 7 contralateral ruptures) while playing soccer. CART analysis selected 9 of 19 independent variables associated with second ACL injury: the 5-jump test, knee collapse on the non-ACL reconstructed leg in a drop vertical jump, tuck jump, limb symmetry index on side hop and the single hop for distance, side difference in ankle dorsiflexion ROM, and scores for the questionnaires ACL-Return to Sport After Injury and the Swedish Universities Scales of Personality subscales of Stress Susceptibility and Adventure Seeking. The accuracy of the model was 89%, with 100% sensitivity and 76% specificity. CART analysis indicated that the interaction of longer jumps in the 5-jump test (>916 cm) with more side difference in ankle dorsiflexion ROM (>-2.5°) and more knee valgus collapse in the nonreconstructed knee (>-1.4 cm) (relative risk, 4.03; 95% CI, 2.21-7.36) best predicted an increased likelihood of a second ACL injury.

CONCLUSION

The risk profiles selected by CART could accurately identify female soccer players at high risk for a second ACL injury. There was an interaction between functional performance, clinical assessment, and psychological factors, and it is reasonable to include these factors in return-to-sport decisions and in athlete screening after ACL injury.

Is There a Role of Meniscal Morphology in the Risk of Noncontact Anterior Cruciate Ligament Rupture? A Case-Control Study

The purpose of this study was to identify the anatomical risk factors and determine the role of meniscal morphology in noncontact anterior cruciate ligament (ACL) rupture. A total of 126 patients (63 with noncontact ACL rupture and 63 age- and sex-matched controls) with intact menisci were included in this retrospective case-control study. On knee magnetic resonance imaging (MRI), meniscal morphometry (anterior, corpus, and posterior heights and widths of each meniscus), tibial slope (medial and lateral separately), notch width index, roof inclination angle, anteromedial bony ridge, tibial eminence area, and Q-angle measurements were assessed. The data were analyzed using multiple regression analyses to identify independent risk factors associated with ACL rupture. Using a univariate analysis, medial and lateral menisci anterior horn heights (p < 0.001; p < 0.003), medial and lateral menisci posterior horn heights (p < 0.001; p < 0.001), lateral meniscus corpus width (p < 0.004), and notch width index (p < 0.001) were significantly higher in the control group. Lateral tibial slope (p < 0.001) and anteromedial bony ridge thickness (p < 0.001) were significantly higher in the ACL rupture group. Multivariate analysis revealed that decreased medial meniscus posterior horn height (odds ratio [OR]: 0.242; p < 0.001), increased lateral meniscus corpus width (OR: 2.118; p < 0.002), increased lateral tibial slope (OR: 1.95; p < 0.001), and decreased notch width index (OR: 0.071; p = 0.046) were independent risk factors for ACL rupture. Notch stenosis, increased lateral tibial slope, decreased medial meniscus posterior horn height, and increased lateral meniscus corpus width are independent anatomical risk factors for ACL rupture. Meniscal morphological variations also play a role in ACL injury. This is a Level III, retrospective case-control study.

Rehabilitation and Return to Sport Assessment after Anterior Cruciate Ligament Injury: Quantifying Joint Kinematics during Complex High-Speed Tasks through Wearable Sensors

The aim of the present study was to quantify joint kinematics through a wearable sensor system in multidirectional high-speed complex movements used in a protocol for rehabilitation and return to sport assessment after Anterior Cruciate Ligament (ACL) injury, and to validate it against a gold standard optoelectronic marker-based system. Thirty-four healthy athletes were evaluated through a full-body wearable sensor (MTw Awinda, Xsens) and a marker-based optoelectronic (Vicon Nexus, Vicon) system during the execution of three tasks: drop jump, forward sprint, and 90° change of direction. Clinically relevant joint angles of lower limbs and trunk were compared through Pearson’s correlation coefficient (r), and the Coefficient of Multiple Correlation (CMC). An excellent agreement (r > 0.94, CMC > 0.96) was found for knee and hip sagittal plane kinematics in all the movements. A fair-to-excellent agreement was found for frontal (r 0.55–0.96, CMC 0.63–0.96) and transverse (r 0.45–0.84, CMC 0.59–0.90) plane kinematics. Movement complexity slightly affected the agreement between the systems. The system based on wearable sensors showed fair-to-excellent concurrent validity in the evaluation of the specific joint parameters commonly used in rehabilitation and return to sport assessment after ACL injury for complex movements. The ACL professionals could benefit from full-body wearable technology in the on-field rehabilitation of athletes.

Differences in Knee Shape between ACL Injured and Non-Injured: A Matched Case-Control Study of 168 Patients

OBJECTIVE

Anterior cruciate ligament (ACL) injury prevention programs could be more effective if we could select patients at risk for sustaining an ACL rupture. The purpose of this study is to identify radiographic shape variants of the knee between patients with and patients without an ACL rupture.

METHODS

We compared the lateral and Rosenberg view X-rays of 168 prospectively followed patients with a ruptured ACL to a control group with intact ACLs, matched for gender, after knee trauma. We used statistical shape modeling software to examine knee shape and find differences in shape variants between both groups.

RESULTS

In the Rosenberg view X-rays, we found five shape variants to be significantly different between patients with an ACL rupture and patients with an intact ACL but with knee trauma. Overall, patients who had ruptured their ACL had smaller, flatter intercondylar notches, a lower lateral tibia plateau, a lower medial spike of the eminence, and a smaller tibial eminence compared to control patients.

CONCLUSION

Patients with an ACL rupture have smaller intercondylar notches and smaller tibial eminences in comparison to patients with an intact ACL after knee trauma.

Prediction of ACL Injuries from Vertical Jump Kinetics in Division 1 Collegiate Athletes

BACKGROUND

The incidence of ACL injuries continues to rise secondary to an increase in sport participation. Evidence supports the use of force plate testing to quantify kinetics during rehabilitation after injury and recovery; however, there is limited current research regarding if jump kinetics can identify athletes who are at higher risk for injury. Altered kinetics could potentially lead to abnormal force dissipation and resultant injury.

PURPOSE

The purpose of this investigation was to identify whether the force-time variables from vertical jumps could predict ACL injuries in collegiate athletes.

STUDY DESIGN

Retrospective cohort.

METHODS

Vertical jump testing is performed by all healthy varsity collegiate athletes at several intervals throughout the athletic year at a Division I institution using a commercially available force plate system with dedicated software. Athletes who sustained an ACL injury between 1/1/15 and 6/1/19 were identified (n=16) and compared to healthy athletes who participated in the same sports (n = 262). ACL injuries were considered for this study if they occurred no more than 10 weeks after a jump test. The outcome variables were load, explode, and drive, operationally defined as the average eccentric rate of force development, average relative concentric force, and concentric relative impulse, respectively, which the system normalized to T scores. Mann-Whitney U tests were used to assess group differences for load, explode, drive, and the ratio between the variables. Logistic regression was used to determine if the battery of variables could predict whether or not an athlete would sustain an ACL injury. The p-value was set to 0.10 for the Mann-Whitney U tests, and 0.05 for the logistic regression.

RESULTS

Significant differences between the ACL and healthy groups were seen for explode (p=0.08), drive (p=0.06), load:explode ratio (p=0.06), and explode:drive ratio (p=0.03). Explode and drive, when entered into the regression equation, showed the ability to predict injury, χ 2 = 6.8, df = 2, p=0.03.

CONCLUSIONS

The vertical jump force plate variables were able to identify athletes who sustained an ACL injury within 66 days of testing. Athletes who sustained an ACL injury demonstrated altered kinetics and less ability to transmit forces during the vertical jump.

LEVEL OF EVIDENCE

3.

Hop Performance After Return to Sport in Anterior Cruciate Ligament-Reconstructed Gaelic Football and Hurling Athletes

PURPOSE

Anterior cruciate ligament (ACL) injuries are among the most severe injuries in the Gaelic Athletic Association. Hop tests measure functional performance after ACL reconstruction as they replicate the key requirements for a match situation. However, research examining functional recovery of ACL-reconstructed Gaelic athletes is lacking. The objective of this study is to determine if athletes restore normal hop symmetry after ACL reconstruction and to examine if bilateral deficiencies persist in hop performance following return to sport.

METHODS

A cross-sectional design was used to evaluate hop performance of 30 ACL-reconstructed Gaelic athletes who had returned to competition and 30 uninjured controls in a battery of hop tests including a single, 6-m, triple, and triple-crossover hop test.

RESULTS

In each test, the mean symmetry score of the ACL reconstruction group was above the cutoff for normal performance of 90% adopted by this study (98%, 99%, 97%, and 99% for the single, 6-m, triple, and triple-crossover hop, respectively). No significant differences in absolute hop scores emerged between involved and control limbs, with the exception of the single-hop test where healthy dominant limbs hopped significantly further than ACL-reconstructed dominant limbs (P = .02). No significant deficits were identified on the noninvolved side.

CONCLUSIONS

The majority of ACL-reconstructed Gaelic athletes demonstrate normal levels of hop symmetry after returning to competition. Suboptimal hop performance can persist on the involved side compared with control limbs. Targeted rehabilitation may be warranted after returning to competition to restore performance to levels of healthy uninjured athletes.

CONSISTENCY OF DYNAMIC KNEE VALGUS KINEMATICS AND PAIN ACROSS FUNCTIONAL TASKS IN FEMALES WITH PATELLOFEMORAL PAIN: A CROSS-SECTIONAL STUDY

Background and Purpose

Dynamic knee valgus has been associated with patellofemoral pain (PFP) during high-level tasks, however, repeated lower-level stresses may be an alternative pain mechanism. The primary purpose of the current study was to examine the consistency of dynamic knee valgus and task-elicited pain demonstrated by females with PFP across four common functional tasks (stair ascent, stair descent, sit-to-stand, and stand-to-sit). A secondary purpose was to assess the correlation between the clinical test of single-limb squat and functional tasks.

Hypothesis

Females with patellofemoral pain will demonstrate a positive relationship in magnitude of dynamic knee valgus and task-elicited pain across functional tasks. Individuals who demonstrated greater dynamic knee valgus and task-elicited pain during the clinical test of single-limb squat would demonstrate greater dynamic knee valgus and task elicited pain during stair ascent/descent and sit-to-stand/stand-to-sit tasks.

Study Design

Cross-sectional study; secondary analysis of a feasibility intervention study.

Methods

Twenty-three women with patellofemoral pain (age: 21.8 SD 3.7 years; BMI: 22.2 SD 2.0 kg/m²) participated. Three-dimensional kinematic data were captured during task completion. Hip and knee frontal and transverse plane angles at 45 ° of knee flexion, and pain using a visual analog scale, were assessed during single-limb squat, stair ascent/descent, and sit-to-stand. Pearson product-moment correlation coefficients were calculated to examine between-task relationships for each variable at the pre-intervention assessment.

Results

Correlation coefficients between tasks ranged from 0.23-0.76 for hip frontal plane measures (7/10 significant relationships, p<0.02), 0.31-0.90 for hip transverse plane measures (7/10 significant, p<0.01), 0.87-0.95 for knee frontal plane measures (10/10 significant, p<0.01), and 0.54-0.86 for knee transverse plane measures (10/10 significant, p<0.01). Correlations spanned 0.59-0.85 for pain during tasks (10/10 significant, p<0.01).

Conclusion

Females with patellofemoral pain demonstrated positive correlations in dynamic knee valgus kinematics and task-elicited pain across five tasks. Movement and pain during the clinical test of single-limb squat test also was correlated with movement and pain during the functional tasks of stair ascent/descent and sit-to-stand.

Level of Evidence

Level 2b.

Introducing an Activity-Based Balance Index for Soccer Players: A Validity and Reliability Study

Objectives: The aim of this study was to evaluate the validity and reliability of introducing a new activity-based balance index using a triaxial accelerometer during activity. Methods: Twenty seven soccer players (age: 14.5 ± 0.4 years old, body mass: 58.3 ± 9.3 kg, height: 172 ± 8 cm) who participated in the national premier league were recruited. The participants were tested for their balance, activity, and skill in four tests: (I) one leg stance; (II) dynamic Y balance; (III) running; and (IV) dribbling slalom. The acceleration of the body was recorded using an accelerometer during those tests. By processing acceleration data, a new activity-based balance index (ABI) was calculated based on the velocity, acceleration, and position index of soccer players. Using intra-class correlation coefficients (ICC), reliability was calculated. Results: Reliability was high (ICC = 0.87 - 0.89; 95% CI = 0.77 - 0.93) in calculating ABI for the three activities performed in the tests. A significant positive correlation between ABI and both static and dynamic balance scores (r = 0.62, P = 0.002) was observed. Furthermore, negative correlation was found significantly between ABI and dribbling scores (r = -0.61, P = 0.026) and Y Balance test (r = 0.6, P = 0.002). Conclusions: In conclusion, the introduced ABI demonstrates great potential to determine balance and skill scores based on accelerometer-based measures.

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).

Assessing thigh muscle balance of male athletes with special emphasis on eccentric hamstring strength

Background: Hamstring strength is important to prevent thigh muscle and knee injuries. Different antagonist-agonist relationships of thigh muscle strength are applied to estimate the injury risk e.g. the intersection point of eccentric hamstring (Hecc) and concentric quadriceps (Qcon) moment-knee flexion angle curves (dynamic control ratio at the equilibrium point = DCRe) and the dynamic control ratio (DCR = Hecc:Qcon). Objective: The aim was to quantify the relationships between DCR, DCRe moments and angles as well as their correlations with peak moments and contractional work of eccentric hamstring and concentric quadriceps exercise. Methods: This cross-sectional study included data from 238 healthy male participants of different sports. They conducted unilateral isokinetic tests obtained at 30°/s and 150°/s for the hamstrings (prone) and the quadriceps (supine). Results: Correlations between DCR and DCRe moments were significant, but weak to moderate in strength (R²_30°/s = 20%, R²_150°/s = 26%). In contrast to DCR (25% ≤ R² ≤ 46%), DCRe moments (80% ≤ R² ≤ 86%) showed very strong relations with peak moments and contractional work of eccentric hamstring exercise. Discussion: DCR and DCRe assess thigh balance by using the same isokinetic raw data. However, weak relations became apparent. DCRe moments were stronger related to eccentric hamstring strength and work than DCR. Therefore, the DCRe moment may serve as meaningful measure of thigh muscle balance because increased eccentric hamstring strength promotes dynamic joint stability and minimizes injury risk.

Return to football training and competition after lockdown caused by the COVID-19 pandemic: medical recommendations

The lockdown caused by the COVID-19 pandemic represents a great unknown regarding the physiological changes induced in elite football players. Although it will differ from country to country, the return to sport for professional football players will follow a forced lockdown never experienced and longer than the normal annual season break. Moreover, in addition to an obvious decrease in performance, the lockdown will possibly lead to an increase of the injury risk. In fact, preseason is always a period with a specific football injury epidemiology, with an increase in the incidence and prevalence of overuse injuries. Therefore, it seems appropriate to recommend that specific training and injury prevention programmes be developed, with careful load monitoring. Training sessions should include specific aerobic, resistance, speed and flexibility training programmes. The aerobic, resistance and speed training should respect some specific phases based on the progressiveness of the training load and the consequent physiological adaptation response. These different phases, based on the current evidence found in the literature, are described in their practical details. Moreover, injury prevention exercises should be incorporated, especially focusing on overuse injuries such as tendon and muscle lesions. The aim of this paper is to provide practical recommendations for the preparation of training sessions for professional footballers returning to sport after the lockdown.

The Effects of Attentional Focus Instructions Specific to Body Movements on Movement Quality and Performance

Contexts: Directing an individual's attention to the effect of the movements (external focus) has been shown to improve performance than directing attention to body movements (internal focus). However, the effect of attentional focus instructions specific to movement quality has not been investigated thoroughly.

OBJECTIVE

To compare the effects of internal and external focus instructions specific to body movements.

DESIGN

Mixed design, 2 (sex) × 2 (instructions).

SETTINGS

Laboratory setting.

PARTICIPANTS

A total of 40 participants (males, n = 20; mean [SD]; age = 22.0 [2.19] y; height = 179.33 [5.90] cm; mass = 77.7 [13.04] kg; females, n = 20; age = 22.0 [3.87] y; height = 164.84 [5.80] cm; mass = 71.48 [20.66] kg) were recruited.

INTERVENTION

Participants completed 2 consecutive jumps (ie, a forward jump from a height and then a maximal vertical jump) with internal focus and external focus instructions. External focus was elicited by placing pieces of tape on the participants' legs.

MAIN OUTCOME MEASURES

Landing quality was measured by the Landing Error Scoring System to assess movement quality, and the vertical jump height was measured by Vertec.

RESULTS

The performance results showed that the external focus condition resulted in superior vertical jump height compared with the internal focus condition (P < .05). Although landing quality did not show significant differences between 2 conditions, the effect size (η2 = .09) indicated that landing quality was better when participants adopted an external, rather than an internal focus of attention (P = .07).

CONCLUSIONS

The body-oriented instructions can be provided externally by adding artificial external cues and directing attention to them. Importantly, the findings were evident in a qualitative assessment that can be adopted by practitioners. The results suggest that practitioners should adopt an external focus cue for performance and also consider using an external focus for movement quality.

Can a Standardized Visual Assessment of Squatting Technique and Core Stability Predict Injury?

O'Connor, S, McCaffrey, N, Whyte, EF, and Moran, KA. Can a standardized visual assessment of squatting technique and core stability predict injury? J Strength Cond Res 34(1): 26-36, 2020-This study examined whether a standardized visual assessment of squatting technique and core stability can predict injury. Male adolescent and collegiate Gaelic players (n = 627) were assessed using the alternative core/trunk stability push-up test and a developed scoring system for the overhead squat and single-leg squat (SLS) that examined both overall impression and segmental criteria. A single summative score from the overall impression scores of all 3 tests was calculated. Sustained injuries were examined over a season. Results indicated that the single summative score did not predict those that sustained a lower-extremity injury, trunk injury, or whole-body injury, and receiver operating characteristic curves were also unable to generate an optimal cutoff point for prediction. When segmental criteria were included in multivariate analyses, the tests were able to predict whole-body injury (p < 0.0001) and lower-extremity injury (p < 0.0001). However, although specificity was high (80.6%, 76.5%), sensitivity of the models was low (40.2%, 44.2%). The most common score was "good" for the overhead squat (46.4%) and SLS (47.6%), and "good" and "excellent" for the alternative core stability push-up test (33.5%, 49.1%), with "poor" core stability increasing the odds of sustaining a lower-extremity injury (odds ratio = 1.52 [0.92-2.51]). The findings suggest that although segmental scoring could be incorporated by strength and conditioning coaches and clinicians, they should be used predominantly as a preliminary screening tool to highlight players requiring a more thorough assessment.

Are Elite Soccer Teams' Preseason Training Sessions Associated With Fewer In-Season Injuries? A 15-Year Analysis From the Union of European Football Associations (UEFA) Elite Club Injury Study

BACKGROUND

Preseason training develops players' physical capacities and prepares them for the demands of the competitive season. In rugby, Australian football, and American football, preseason training may protect elite players against in-season injury. However, no study has evaluated this relationship at the team level in elite soccer.

PURPOSE/HYPOTHESIS

The aim of this study was to investigate whether the number of preseason training sessions completed by elite soccer teams was associated with team injury rates and player availability during the competitive season. It was hypothesized that elite soccer teams who participate in more preseason training will sustain fewer injuries during the competitive season.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

We used the Union of European Football Associations (UEFA) injury dataset to analyze 44 teams for up to 15 seasons (total, 244 team-seasons). Separate linear regression models examined the association between the number of team preseason training sessions and 5 in-season injury measures. Injury-related problems per team were quantified by totals of the following: (1) injury burden, (2) severe injury incidence, (3) training attendance, (4) match availability, and (5) injury incidence.

RESULTS

Teams averaged 30 preseason training sessions (range, 10-51). A greater number of preseason training sessions was associated with less injury load during the competitive season in 4 out of 5 injury-related measures. Our linear regression models revealed that for every 10 additional preseason training sessions that the team performed, the in-season injury burden was 22 layoff days lower per 1000 hours (P = .002), the severe injury incidence was 0.18 severe injuries lower per 1000 hours (P = .015), the training attendance was 1.4 percentage points greater (P = .014), and the match availability was 1.0 percentage points greater (P = .042). As model fits were relatively low (adjusted R² = 1.3%-3.2%), several factors that contribute to in-season injury outcomes were unaccounted for.

CONCLUSION

Teams that performed a greater number of preseason training sessions had "healthier" in-season periods. Many other factors also contribute to in-season injury rates. Understanding the benefit of preseason training on in-season injury patterns may inform sport teams' planning and preparation.

Risk Factors for Early Subsequent (Revision or Contralateral) ACL Reconstruction: A Retrospective Database Study

Background:

Many factors contribute to the risk for subsequent anterior cruciate ligament reconstruction (ACLR) within 2 years from the index procedure.

Purpose/Hypothesis:

The purpose of this study was 2-fold: (1) to evaluate the incidence of subsequent (revision or contralateral) ACLR at 2 years in a large cohort and (2) to explore the association between patient-specific factors and early subsequent ACLR risk by age group. We hypothesize that 2-year subsequent (revision or contralateral) ACLR rates will be low and that risk factors for subsequent (revision or contralateral) ACLR will vary depending on a patient’s age group.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

The California Office of Statewide Health Planning and Development Ambulatory Surgery Database was retrospectively reviewed to assess the incidence of 2-year subsequent (revision or contralateral) ACLR and to identify patient-specific risk factors for early subsequent (revision or contralateral) ACLR by age group between 2005 and 2014.

Results:

Of 94,108 patients included, the rate of subsequent (revision or contralateral) ACLR was highest in patients younger than 21 years (2.4 per 100 person-years; 95% CI, 2.3-2.6) and lowest in those older than 40 years (1.3 per 100 person-years; 95% CI, 1.2-1.4). Younger age, white race (compared with Hispanic in all age groups and Asian in age <21 or >40 years), private insurance if age younger than 21 years, public insurance or worker's compensation claims if age older than 30 years were significantly associated with an increased risk of subsequent (revision or contralateral) ACLR at 2 years.

Conclusion:

Results of the present study provide insight into subsequent (revision or contralateral) ACL reconstruction, which can be used to assess and modify treatment for at-risk patients and highlight the need for data mining to generate clinically applicable research using national and international databases.

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