Real-time assessment and neuromuscular training feedback techniques to prevent ACL injury in female athletes

Development of a Clinician-Rated Drop Vertical Jump Scale for Patients Undergoing Rehabilitation After Anterior Cruciate Ligament Reconstruction: A Delphi Approach

Study Design Delphi panel study. Background Biomechanical parameters measured during a drop vertical jump task are risk factors for anterior cruciate ligament (ACL) injury and are targeted during rehabilitation after ACL reconstruction. A clinically feasible tool that quantifies observed performance on the drop vertical jump would help inform treatment efforts. The content and scoring of such a tool should be deliberated on by a group of experts throughout its development. Objectives To establish consensus on the content and scoring of a clinician-rated drop vertical jump scale (DVJS) for use during rehabilitation after ACL reconstruction. Methods Using a modified Delphi process, a panel of experts (researchers and clinicians) on the risk factors, prevention, treatment, and biomechanics of ACL injury anonymously critiqued versions of a DVJS. The DVJS was developed iteratively, based on the feedback from the panel, using Likert scale responses to questions and providing written comments. Three to 5 rounds were planned a priori, with a requirement of 75% agreement on included items after the final round. Results Twenty of the 31 invited experts (65%) participated. Approximately 93% agreement was achieved after the fourth round. Final items on the scale included the rating of knee valgus collapse (no collapse to extreme collapse) and the presence of other undesirable movements, including lateral trunk lean, insufficient knee flexion, and limb-to-limb asymmetry. Conclusion The Delphi process resulted in a beta version of a DVJS. Expert consensus was achieved on its content and scoring to support further clinical testing of the scale. J Orthop Sports Phys Ther 2017;47(8):557-564. Epub 6 Jul 2017. doi:10.2519/jospt.2017.7183.

A Kinect-based movement assessment system: marker position comparison to Vicon

Accurate movement analysis systems are prohibitive in cost and size to be accessible to the general population, while commercially available, affordable systems lack the accuracy needed for clinical relevance. To address these limitations, we developed a Depth Camera Movement Assessment System (DCMAS) featuring an affordable, widely available depth camera (e.g. Microsoft Kinect). After examining 3D position data for markers adhered to participants and a flat surface, captured with both DCMAS and the industry standard Vicon system, we demonstrated DCMAS obtained measurements comparable, within soft tissue artifact, to the Vicon system, paving the way for a breakthrough technology in preventative medicine.

Neuromuscular Risk Factors for Knee and Ankle Ligament Injuries in Male Youth Soccer Players

Injuries reported in male youth soccer players most commonly occur in the lower extremities, and include a high proportion of ligament sprains at the ankle and knee with a lower proportion of overuse injuries. There is currently a paucity of available literature that examines age- and sex-specific injury risk factors for such injuries within youth soccer players. Epidemiological data have reported movements that lead to non-contact ligament injury include running, twisting and turning, over-reaching and landing. Altered neuromuscular control during these actions has been suggested as a key mechanism in females and adult populations; however, data available in male soccer players is sparse. The focus of this article is to review the available literature and elucidate prevalent risk factors pertaining to male youth soccer players which may contribute to their relative risk of injury.

Examining the Relationship Between the Functional Movement Screen and the Landing Error Scoring System in an Active, Male Collegiate Population

Everard, EM, Harrison, AJ, and Lyons, M. Examining the relationship between the functional movement screen and the landing error scoring system in an active, male collegiate population. J Strength Cond Res 31(5): 1265-1272, 2017-In recent years, there has been an increasing focus on movement screening as the principal aspect of preparticipation testing. Two of the most common movement screening tools are the Functional Movement Screen (FMS) and the Landing Error Scoring System (LESS). Several studies have examined the reliability and validity of these tools, but so far, there have been no studies comparing the results of these 2 screening tools against each other. Therefore, the purpose of this study was to determine the relationship between FMS scores and LESS scores. Ninety-eight male college athletes actively competing in sport (Gaelic games, soccer, athletics, boxing/mixed martial arts, Olympic weightlifting) participated in the study and performed the FMS and LESS screens. Both the 21-point and 100-point scoring systems were used to score the FMS. Spearman's correlation coefficients were used to determine the relationship between the 2 screening scores. The results showed a significant moderate correlation between FMS and LESS scores (rho 100 and 21 point = -0.528; -0.487; p < 0.001). In addition, r values of 0.26 and 0.23 indicate a poor shared variance between the 2 screens. The results indicate that performing well in one of the screens does not necessarily equate to performing well in the other. This has practical implications as it highlights that both screens may assess different movement patterns and should not be used as a substitute for each other.

Intra- and Inter-Rater Reliability of the Modified Tuck Jump Assessment

The Tuck Jump Assessment (TJA) is a clinician-friendly screening tool that was designed to support practitioners with identification of neuromuscular deficits associated with anterior cruciate ligament injury. This study aimed to evaluate the inter- and intra-rater reliability of the modified scoring (0 to 2) TJA to add an additional range of objectivity for each criterion. A total of 24 elite youth volleyball athletes (12 males and 12 females) were included in this study. Each participant's recorded performance of the TJA was scored independently by two raters across ten criteria using the modified scale. The two raters then scored the same videos one week later. Another investigator who was blind to the identity of the raters analyzed the scores from both raters for each participant. Kappa coefficient (k) and percentage of exact agreement (PEA) for both intra- and inter-rater reliability were analyzed for each item. Intraclass correlation coefficients (ICC) were calculated to determine intra- and inter-rater reliability of the modified TJA total score. Intra- and inter-rater k was good to excellent for most items (0.65-0.91). Average PEA between the two raters and two sessions ranged from 83.3 to 100% in all scored items. The ICC for the total score was excellent in both inter- and inter-rater correlations (0.94-0.96). This research demonstrated that the modified version of the TJA predominantly shows good to excellent intra- and inter-rater reliability in all analyzed criteria.

Motor learning strategies in basketball players and its implications for ACL injury prevention: a randomized controlled trial

PURPOSE

Adding external focus of attention (EF, focus on the movement effect) may optimize current anterior cruciate ligament (ACL) injury prevention programmes. The purpose of the current study was to investigate the effects of an EF, by a visual stimulus and an internal focus, by a verbal stimulus during unexpected sidestep cutting in female and male athletes and how these effects remained over time.

METHODS

Ninety experienced basketball athletes performed sidestep cutting manoeuvres in three sessions (S1, S2 and S3). In this randomized controlled trial, athletes were allocated to three groups: visual (VIS), verbal (VER) and control (CTRL). Kinematics and kinetics were collected at the time of peak knee frontal plane moment.

RESULTS

Males in the VIS group showed a larger vertical ground reaction force (S1: 25.4 ± 3.1 N/kg, S2: 25.8 ± 2.9 N/kg, S3: 25.2 ± 3.2 N/kg) and knee flexion moments (S1: -3.8 ± 0.9 Nm/kg, S2: -4.0 ± 1.2 Nm/kg, S3: -3.9 ± 1.3 Nm/kg) compared to the males in the VER and CTRL groups and to the females in the VIS group (p < 0.05). Additionally, the males in the VIS group reduced knee valgus moment and the females in the VER group reduced knee varus moment over time (n.s.).

CONCLUSION

Male subjects clearly benefit from visual feedback. Females may need different feedback modes to learn a correct movement pattern. Sex-specific learning preferences may have to be acknowledged in day by day practice. Adding video instruction or feedback to regular training regimens when teaching athletes safe movement patterns and providing individual feedback might target suboptimal long-term results and optimize ACL injury prevention programmes.

LEVEL OF EVIDENCE

I.

Reliability of the Tuck Jump Injury Risk Screening Assessment in Elite Male Youth Soccer Players

Read, PJ, Oliver, JL, de Ste Croix, MBA, Myer, GD, and Lloyd, RS. Reliability of the tuck jump injury risk screening assessment in elite male youth soccer players. J Strength Cond Res 30(6): 1510-1516, 2016-Altered neuromuscular control has been suggested as a mechanism for injury in soccer players. Ligamentous injuries most often occur during dynamic movements, such as decelerations from jump-landing maneuvers where high-risk movement patterns are present. The assessment of kinematic variables during jump-landing tasks as part of a preparticipation screen is useful in the identification of injury risk. An example of a field-based screening tool is the repeated tuck jump assessment. The purpose of this study was to analyze the within-subject variation of the tuck jump screening assessment in elite male youth soccer players. Twenty-five pre-peak height velocity (PHV) and 25 post-PHV elite male youth soccer players from the academy of a professional English soccer club completed the assessment. A test-retest design was used to explore the within-subject intersession reliability. Technique was graded retrospectively against the 10-point criteria set out in the screening protocol using two-dimensional video cameras. The typical error range reported for tuck jump total score (0.90-1.01 in pre-PHV and post-PHV players respectively) was considered acceptable. When each criteria was analyzed individually, kappa coefficient determined that knee valgus was the only criterion to reach substantial agreement across the two test sessions for both groups. The results of this study suggest that although tuck jump total score may be reliably assessed in elite male youth soccer players, caution should be applied in solely interpreting the composite score due to the high within-subject variation in a number of the individual criteria. Knee valgus may be reliably used to screen elite youth male soccer players for this plyometric technique error and for test-retest comparison.

FUNCTIONAL HOP TESTS AND TUCK JUMP ASSESSMENT SCORES BETWEEN FEMALE DIVISION I COLLEGIATE ATHLETES PARTICIPATING IN HIGH VERSUS LOW ACL INJURY PRONE SPORTS: A CROSS SECTIONAL ANALYSIS

BACKGROUND

Although functional tests including the single leg hop (SLH), triple hop (TH), cross over hop (COH) for distance, and the tuck jump assessment (TJA) are used for return to play (RTP) criteria for post anterior cruciate ligament (ACL) injury, sport-specific baseline measurements are limited.

PURPOSE

The purpose of this study was to examine differences in SLH, TH, and COH distance and limb symmetry index (LSI), as well as total scores, number of jumps, and individual flaws of the TJA in 97 injury-free Division I (DI) collegiate female student athletes participating in ACL injury prone vs. non ACL injury prone sports. The hypothesis was that significant mean differences and asymmetries (LSI) would exist between the two groups in SLH, TH, COH and TJA.

STUDY DESIGN

Cross sectional.

METHODS

Due to research suggesting inherent ACL injury risk associated with specific sport involvement, participants were grouped into high (HR, n=57) and low (LR, n=40) ACL injury risk based on participating in a sport with high or low ACL injury rates. The HR group was composed of athletes participating in soccer, basketball, and volleyball, while the LR group athletes participated in diving, cross country, and track and field. Participants performed all standard functional tests (SFT) and side-to-side differences for each participant as well as between group differences were assessed for the hop tests. The LSI, a ratio frequently used to gauge athletes' readiness for RTP post injury, was also assessed for between group differences. The TJA was compared between the groups on individual flaws, overall scores, and number of jumps performed.

RESULTS

No between group differences for hop distances were found, with medium to large effect sizes for SLH, TH, and COH. The HR group had a higher TJA score, number of jumps, and higher proportion of the flaw of 'foot placement not shoulder width apart'.

CONCLUSION

Although most SFT's showed no significant differences between athlete groups, some differences were seen in the TJA; the HR group showed an increase in 'foot placement not shoulder width apart' flaw, higher overall flaw scores, and overall jumped more times compared to the LR group. These results may warrant caution in relying solely on SFT for RTP decisions, due to potential asymmetries seen in an uninjured population with baseline testing.

LEVEL OF EVIDENCE

4.

Mechanisms, prediction, and prevention of ACL injuries: Cut risk with three sharpened and validated tools

Economic and societal pressures influence modern medical practice to develop and implement prevention strategies. Anterior cruciate ligament (ACL) injury devastates the knee joint leading to short term disability and long term sequelae. Due to the high risk of long term osteoarthritis in all treatment populations following ACL injury, prevention is the only effective intervention for this life-altering disruption in knee health. The "Sequence of Prevention" Model provides a framework to monitor progress towards the ultimate goal of preventing ACL injuries. Utilizing this model, our multidisciplinary collaborative research team has spent the last decade working to delineate injury mechanisms, identify injury risk factors, predict which athletes are at-risk for injury, and develop ACL injury prevention programs. Within this model of injury prevention, modifiable factors (biomechanical and neuromuscular) related to injury mechanisms likely provide the best opportunity for intervention strategies aimed to decrease the risk of ACL injury, particularly in female athletes. Knowledge advancements have led to the development of potential solutions that allow athletes to compete with lowered risk of ACL injury. Design and integration of personalized clinical assessment tools and targeted prevention strategies for athletes at high risk for ACL injury may transform current prevention practices and ultimately significantly reduce ACL injury incidence. This 2016 OREF Clinical Research Award focuses on the authors' work and contributions to the field. The author's acknowledge the many research groups who have contributed to the current state of knowledge in the fields of ACL injury mechanisms, injury risk screening and injury prevention strategies. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1843-1855, 2016.

Comparison of Female Collegiate Athletes and College Age Cohort in Tuck Jump Assessment

Smith, CA, Olson, BK, Olson, LA, Chimera, NJ, and Warren, M. Comparison of female collegiate athletes and college age cohort in tuck jump assessment. J Strength Cond Res 31(4): 1048-1054, 2017-The tuck jump assessment (TJA) is a plyometric jumping assessment with 10 flaw criteria against which technique is assessed over a 10-second interval. The TJA has been reported as a tool for identifying neuromuscular deficits that increase risk for anterior cruciate ligament injury, but group specific data on female TJA scores are limited. No cut point has been developed for groups with different activity levels or participation in athletics. This study investigated the association between TJA score and athletic participation in college-aged females. One hundred twenty-one females (53 collegiate athletes and 68 college students) completed the TJA. TJA score was the sum of flaws for the 10 criteria observed, and the number of jumps was recorded. Poisson regression was used to assess the association between TJA score and number of jumps. The association between each of the 10 flaws between groups was assessed with the chi-square test. No significant association was found between groups for TJA score (mean ± SD: 4.66 ± 1.07 athletes; 5.45 ± 1.05 college cohort; p = 0.06; β = 0.82). Athletes jumped significantly more times (12.23 ± 1.04 athletes; 9.35 ± 1.04 college cohort). Athletes had a lower proportion of 2 flaws: "thighs do not reach parallel" and "pause between jumps." Lower statistical power may limit interpretation of the remaining flaws. The lack of control of the number of jumps may impact TJA score. To improve the TJA usefulness on the field and clinic, the protocol may need to standardize the number of jumps.

A Systematic Evaluation of Field-Based Screening Methods for the Assessment of Anterior Cruciate Ligament (ACL) Injury Risk

BACKGROUND

Laboratory-based measures provide an accurate method to identify risk factors for anterior cruciate ligament (ACL) injury; however, these methods are generally prohibitive to the wider community. Screening methods that can be completed in a field or clinical setting may be more applicable for wider community use. Examination of field-based screening methods for ACL injury risk can aid in identifying the most applicable method(s) for use in these settings.

OBJECTIVE

The objective of this systematic review was to evaluate and compare field-based screening methods for ACL injury risk to determine their efficacy of use in wider community settings.

DATA SOURCES

An electronic database search was conducted on the SPORTDiscus™, MEDLINE, AMED and CINAHL databases (January 1990-July 2015) using a combination of relevant keywords. A secondary search of the same databases, using relevant keywords from identified screening methods, was also undertaken.

STUDY SELECTION

Studies identified as potentially relevant were independently examined by two reviewers for inclusion. Where consensus could not be reached, a third reviewer was consulted. Original research articles that examined screening methods for ACL injury risk that could be undertaken outside of a laboratory setting were included for review.

STUDY APPRAISAL AND SYNTHESIS METHODS

Two reviewers independently assessed the quality of included studies. Included studies were categorized according to the screening method they examined. A description of each screening method, and data pertaining to the ability to prospectively identify ACL injuries, validity and reliability, recommendations for identifying 'at-risk' athletes, equipment and training required to complete screening, time taken to screen athletes, and applicability of the screening method across sports and athletes were extracted from relevant studies.

RESULTS

Of 1077 citations from the initial search, a total of 25 articles were identified as potentially relevant, with 12 meeting all inclusion/exclusion criteria. From the secondary search, eight further studies met all criteria, resulting in 20 studies being included for review. Five ACL-screening methods-the Landing Error Scoring System (LESS), Clinic-Based Algorithm, Observational Screening of Dynamic Knee Valgus (OSDKV), 2D-Cam Method, and Tuck Jump Assessment-were identified. There was limited evidence supporting the use of field-based screening methods in predicting ACL injuries across a range of populations. Differences relating to the equipment and time required to complete screening methods were identified.

LIMITATIONS

Only screening methods for ACL injury risk were included for review. Field-based screening methods developed for lower-limb injury risk in general may also incorporate, and be useful in, screening for ACL injury risk.

CONCLUSIONS

Limited studies were available relating to the OSDKV and 2D-Cam Method. The LESS showed predictive validity in identifying ACL injuries, however only in a youth athlete population. The LESS also appears practical for community-wide use due to the minimal equipment and set-up/analysis time required. The Clinic-Based Algorithm may have predictive value for ACL injury risk as it identifies athletes who exhibit high frontal plane knee loads during a landing task, but requires extensive additional equipment and time, which may limit its application to wider community settings.

Use of clinical movement screening tests to predict injury in sport

Clinical movement screening tests are gaining popularity as a means to determine injury risk and to implement training programs to prevent sport injury. While these screens are being used readily in the clinical field, it is only recently that some of these have started to gain attention from a research perspective. This limits applicability and poses questions to the validity, and in some cases the reliability, of the clinical movement tests as they relate to injury prediction, intervention, and prevention. This editorial will review the following clinical movement screening tests: Functional Movement Screen™, Star Excursion Balance Test, Y Balance Test, Drop Jump Screening Test, Landing Error Scoring System, and the Tuck Jump Analysis in regards to test administration, reliability, validity, factors that affect test performance, intervention programs, and usefulness for injury prediction. It is important to review the aforementioned factors for each of these clinical screening tests as this may help clinicians interpret the current body of literature. While each of these screening tests were developed by clinicians based on what appears to be clinical practice, this paper brings to light that this is a need for collaboration between clinicians and researchers to ensure validity of clinically meaningful tests so that they are used appropriately in future clinical practice. Further, this editorial may help to identify where the research is lacking and, thus, drive future research questions in regards to applicability and appropriateness of clinical movement screening tools.

Lower Limb Neuromuscular Asymmetry in Volleyball and Basketball Players

The primary objective of the present study was to evaluate the agreement between the dominant leg (DL) (determined subjectively) and the stronger leg (SL) (determined via a functional test) in a group of basketball and volleyball players. The secondary objective was to calculate lower limb neuromuscular asymmetry when comparing the DL vs the non-dominant leg (NDL) and the SL vs the weaker (WL) leg in the whole group and when differentiating by sex. Seventy-nine male and female volleyball and basketball players (age: 23.7 ± 4.5 years) performed three single-leg vertical countermovement jumps (SLVCJ) on a contact mat. Vertical jump height and an inter-limb asymmetry index (ASI) were determined. Only 32 (40%) of the subjects had a concordance between the perception of their dominant leg and the limb reaching the highest jump height. Using the DL as the discriminating variable, significant (p<0.05) inter-limb differences were found in the total group of players. When comparing between sexes, significant differences (p<0.05) arose in the female group only. With regard to the WL vs. the SL, significant (p<0.05) differences were noted in the whole group and when stratified into males and females. The mean ASI ranged from 9.31% (males) to 12.84% (females) and from 10.49% (males) to 14.26% (females), when comparing the DL vs. the NDL and the SL vs. the WL, respectively. Subjective expression of leg dominance cannot be used as a predictor of limb jump performance. Vertical jump asymmetry of 10-15% exists and this can be considered as a reference value for male and female basketball and volleyball players.

Association of y balance test reach asymmetry and injury in division I athletes

PURPOSE

The Y balance test (YBT) is a screen of dynamic balance requiring stance leg balance while the contralateral leg reaches in anterior (ANT), posteromedial (PM), and posterolateral (PL) directions. YBT has been proposed as a screen for injury risk; however, limited research has examined the association between YBT and injury. The purpose of this study was to examine the association between YBT (asymmetry and composite score (CS)) and noncontact injury in a sample of Division I (DI) college athletes from multiple sports.

METHODS

DI college athletes were screened with the YBT during the preparticipation examination to determine asymmetry (absolute difference between legs in ANT, PL, and PM) and CS (summed average of right/left ANT, PL, and PM normalized to leg length). Participants were followed throughout the sport season, and noncontact injuries requiring athletic training staff intervention were recorded for analysis. Demographic variables between injured and uninjured athletes were assessed with independent t-tests. Receiver operating characteristic (ROC) curves determined optimal cut points for predicting injury on the basis of CS and asymmetry. CS was analyzed as a continuous variable, as ROC curves were unable to maximize sensitivity and specificity. Logistic regression models adjusted for sport and previous injury determined the odds of injury on the basis of asymmetry and CS.

RESULTS

One hundred and eighty-four participants were included in analysis; 81 were injured. ROC curves determined asymmetry >4 cm (sensitivity, 59%; specificity, 72%) as the optimal cut point for predicting injury. Only ANT asymmetry was significantly associated with noncontact injury (odds ratio, 2.33; 95% confidence interval, 1.15-4.76).

CONCLUSIONS

ANT asymmetry >4 cm was associated with increased risk of noncontact injury. CS in this sample of DI athletes was not associated with increased risk of injury.

Motion Analysis and the Anterior Cruciate Ligament: Classification of Injury Risk

Anterior cruciate ligament (ACL) injuries are common, catastrophic events that incur large expense and lead to degradation of the knee. As such, various motion capture techniques have been applied to identify athletes who are at increased risk for suffering ACL injuries. The objective of this clinical commentary was to synthesize information related to how motion capture analyses contribute to the identification of risk factors that may predict relative injury risk within a population. Individuals employ both active and passive mechanisms to constrain knee joint articulation during motion. There is strong evidence to indicate that athletes who consistently classify as high-risk loaders during landing suffer from combined joint stability deficits in both the active and passive knee restraints. Implementation of prophylactic neuromuscular interventions and biofeedback can effectively compensate for some of the deficiencies that result from poor control of the active knee stabilizers and reduce the incidence of ACL injuries.

Training the developing brain part II: cognitive considerations for youth instruction and feedback

Growing numbers of youth participating in competitive, organized physical activity have led to a concern for the risk of sports-related injuries during important periods of human development. Recent studies have demonstrated the ability of integrative neuromuscular training (INT) to enhance athletic performance and reduce the risk of sports-related injuries in youth. Successful implementation of INT necessitates instruction from knowledgeable and qualified instructors who understand the unique physical, cognitive, and psychosocial characteristics of the youth to provide appropriate training instruction and feedback. Principles of a classical theory of cognitive development provide a useful context for discussion of developmentally appropriate methods and strategies for INT instruction of youth. INT programs that consider these developmentally appropriate approaches will provide a controlled efficacious environment for youth to improve athletic performance and reduce risk of sports-related injury, thus promoting a healthy active lifestyle beyond an individual's formative years.

The Variants Within the COL5A1 Gene are Associated with Reduced Risk of Anterior Cruciate Ligament Injury in Skiers

The purpose of this study was to examine the association of the BstUI RFLP C/T (rs 12722) and DpnII RFLP C/T (rs 13946) COL5A1 polymorphisms, individually and as haplotypes, with anterior cruciate ligament ruptures in recreational skiers. Subjects were 138 male recreational skiers with surgically diagnosed primary anterior cruciate ligament ruptures. The control group consisted of 183 apparently healthy male recreational skiers, who were without any self-reported history of ligament or tendon injury. DNA was extracted from buccal cells donated by the subjects and genotyping was carried out using real-time PCR. The genotype distributions for both polymorphisms met Hardy-Weinberg expectations in both groups. There were no significant differences in genotype distribution of allele frequencies of COL5A1 BstUI RFLP C/T and COL5A1 DpnII RFLP C/T polymorphisms between the ACL rupture and control groups. The T-T (BstUI RFLP T, DpnII RFLP T) haplotype was the most common (55.6%). The haplotype T-C was not present in any of the subjects. There was an underrepresentation tendency of the C-T haplotype in the study group compared to controls under recessive mode of inheritance. Higher frequency of the COL5A1 BstUI RFLP C/T and COL5A1DpnII RFLP C/T polymorphisms haplotype is associated with reduced risk of anterior cruciate ligament injury in a group of apparently healthy male recreational skiers.

The Back Squat Part 2: Targeted Training Techniques to Correct Functional Deficits and Technical Factors that Limit Performance

The back squat is a well-researched and widely used exercise to enhance fundamental movement competency that creates a foundation for optimal mechanical strategies during a broad range of activities. The primary commentary introduced the Back Squat Assessment (BSA): a criterion based assessment of the back squat that delineates 30 potentially observable functional deficits. This follow-up commentary provides a targeted system of training cues and exercises to supplement the BSA to guide corrective intervention. We propose a criterion driven approach to corrective exercise that can support practitioners in their goal to help individuals achieve movement competency in the back squat.

A Commentary on Real-Time Biofeedback to Augment Neuromuscular Training for ACL Injury Prevention in Adolescent Athletes

Anterior cruciate ligament injury and the associated long-term sequelae, such as immediate reductions in physical inactivity, increased adiposity and increased risk of osteoarthritis throughout adulthood, are a major health concern for adolescent athletes. Current interventions for injury prevention may have limited effectiveness, are susceptible to issues of compliance and have not achieved the widespread acceptance necessary to promote full adoption. Neuromuscular training (NMT) is a well-established training intervention introduced to affect change in modifiable biomechanical risk factors to reduce the risk of injury in these athletes. Despite moderate success, neuromuscular training is still limited by its reliance on subjective feedback and after the fact (i.e., offline) objective feedback techniques. The purpose of this commentary is to discuss technological tools that could be used to enhance and objectify targeted biofeedback interventions to complement NMT. Electromyography, force plates, motion sensors, and camera-based motion capture systems are innovative tools that may have realistic feasibility for integration as biofeedback into NMT programs to improve training outcomes. Improved functional deficit identification and corrective analysis may further improve and optimize athletic performance, and decrease the risk of sports-related injury during sport performance. Key pointsSpecific, targeted interventions that isolate injury risk factors and can help correct modifiable neuromuscular deficits are essential.Current training interventions for anterior cruciate ligament (ACL) injury prevention have only demonstrated limited effectiveness and have not achieved the widespread acceptance necessary to promote full adoption to reduce ACL injury rates.The paper provides an overview of innovative strategies and technological tools that could be used to enhance and objectify targeted biofeedback interventions to complement neuromuscular training (NMT) including electromyography, force plates, motion sensors, and camera-based motion capture systems.These strategies utilize biomechanical, physiological, or neuromotor variables for training, automate the quantitative measurement of those variables through a variety of technological modalities, and then feed those measured variables via software to provide information in simplified form for online, visual biofeedback displays.

Neuromuscular asymmetries in the lower limbs of elite female youth basketball players and the application of the skillful limb model of comparison

OBJECTIVES

Compare the ability of commonly used comparison models to detect neuromuscular asymmetries. A secondary purpose was to determine which neuromuscular task(s) has the greatest sensitivity to identify asymmetries based on the ASI (asymmetry index) calculation.

METHODS

Elite female youth basketball players (N = 29, age = 15.7 ± 1.34 y) performed the single leg countermovement jump in vertical, horizontal, and lateral directions, the star excursion balance test in the anterior, posteromedial, and posterolateral directions, and the sprint test with change of direction. Paired t-tests compared right and left limbs, the dominant (DL) and non-dominant (NDL) limbs, and the more/less skillful limbs.

RESULTS

The coincident identification between the more skillful leg and the leg subjectively described as the DL was low for all of the tasks performed (35%-52%). There were significant differences between the more and less skillful legs for all tasks, while performances between the right and left limbs and DL and NDL differed significantly for only one task each. The largest ASI detected in this study was found in the vertical single leg countermovement jump (14.11%).

CONCLUSIONS

The skillful limb model of comparison may be more useful than other models to detect neuromuscular asymmetries.

High knee abduction moments are common risk factors for patellofemoral pain (PFP) and anterior cruciate ligament (ACL) injury in girls: is PFP itself a predictor for subsequent ACL injury?

BACKGROUND

Identifying risk factors for knee pain and anterior cruciate ligament (ACL) injury can be an important step in the injury prevention cycle.

OBJECTIVE

We evaluated two unique prospective cohorts with similar populations and methodologies to compare the incidence rates and risk factors associated with patellofemoral pain (PFP) and ACL injury.

METHODS

The 'PFP cohort' consisted of 240 middle and high school female athletes. They were evaluated by a physician and underwent anthropometric assessment, strength testing and three-dimensional landing biomechanical analyses prior to their basketball season. 145 of these athletes met inclusion for surveillance of incident (new) PFP by certified athletic trainers during their competitive season. The 'ACL cohort' included 205 high school female volleyball, soccer and basketball athletes who underwent the same anthropometric, strength and biomechanical assessment prior to their competitive season and were subsequently followed up for incidence of ACL injury. A one-way analysis of variance was used to evaluate potential group (incident PFP vs ACL injured) differences in anthropometrics, strength and landing biomechanics. Knee abduction moment (KAM) cut-scores that provided the maximal sensitivity and specificity for prediction of PFP or ACL injury risk were also compared between the cohorts.

RESULTS

KAM during landing above 15.4 Nm was associated with a 6.8% risk to develop PFP compared to a 2.9% risk if below the PFP risk threshold in our sample. Likewise, a KAM above 25.3 Nm was associated with a 6.8% risk for subsequent ACL injury compared to a 0.4% risk if below the established ACL risk threshold. The ACL-injured athletes initiated landing with a greater knee abduction angle and a reduced hamstrings-to-quadriceps strength ratio relative to the incident PFP group. Also, when comparing across cohorts, the athletes who suffered ACL injury also had lower hamstring/quadriceps ratio than the players in the PFP sample (p<0.05).

CONCLUSIONS

In adolescent girls aged 13.3 years, >15 Nm of knee abduction load during landing is associated with greater likelihood of developing PFP. Also, in girls aged 16.1 years who land with >25 Nm of knee abduction load during landing are at increased risk for both PFP and ACL injury.

The back squat: A proposed assessment of functional deficits and technical factors that limit performance

Fundamental movement competency is essential for participation in physical activity and for mitigating the risk of injury, which are both key elements of health throughout life. The squat movement pattern is arguably one of the most primal and critical fundamental movements necessary to improve sport performance, to reduce injury risk and to support lifelong physical activity. Based on current evidence, this first (1 of 2) report deconstructs the technical performance of the back squat as a foundation training exercise and presents a novel dynamic screening tool that incorporates identification techniques for functional deficits that limit squat performance and injury resilience. The follow-up report will outline targeted corrective methodology for each of the functional deficits presented in the assessment tool.

Increased medial foot loading during drop jump in subjects with patellofemoral pain

PURPOSE

To compare medial-to-lateral plantar forces during drop jump and single leg squat in individuals with and without patellofemoral pain.

METHODS

This cross-sectional study compared 23 young adults with patellofemoral pain to 20 age- and sex-matched controls without knee pain. The plantar pressure distribution was collected during drop jump and single leg squat using pressure-sensitive Pedar insoles, inserted into a standard flat shoe. The primary outcome was the medial-to-lateral force, quantified as the peak force under the medial forefoot as the percentage of force under the total forefoot during drop jump. Secondary outcomes included peak medial-to-lateral force during single leg squat and mean forces during drop jump and single leg squat.

RESULTS

The primary outcome showed that individuals with patellofemoral pain had a 22% higher medial-to-lateral peak force during drop jump, (p=0.03). Secondary outcomes showed 32% higher medial-to-lateral peak force during single leg squat (p=0.01) and 19-23% higher medial-to-lateral mean force during drop jump and single leg squat (p=0.02-0.04).

CONCLUSION

These findings indicate that individuals with patellofemoral pain display a more medially oriented loading pattern of the forefoot compared to individuals without knee pain. This loading pattern may be associated with the distribution of forces acting on the patellofemoral joint and suggest treatment of PFP should consider interventions that target normalisation of foot loading.

LEVEL OF EVIDENCE

III.

Diagnosis and management of acute medial tibial stress syndrome in a 15 year old female surf life-saving competitor

BACKGROUND AND PURPOSE

As the profound health and cost benefits of physical activity to society are established and participation guidelines implemented, health practitioners are increasingly expected to utilize efficacious and justified injury management and prevention strategies. The complex and multifactorial nature of sports injury makes elucidation of multiple risk factors and how they may subtly and variably interact, difficult. The purpose of this case report is to discuss the differential diagnosis, acute management and rehabilitation of a case of medial tibial stress syndrome (MTSS) in a surf life-saving athlete, in the context of sports injury prevention.

CASE DESCRIPTION

The subject of this case study, a 15 year old female surf life-saving competitor, presented to the physiotherapist (PT) with recent onset, first episode, bilateral, diffuse posteromedial shin pain. Differential diagnosis, acute management, rehabilitation and preventative strategies for the subject are presented.

DISCUSSION

Emerging injury surveillance research in surf life-saving suggests minor and major trauma as primary causative factors, however, the significance of high training volumes is likely underestimated. The influence of biomechanical, and subtle arthrokinematic dysfunctions on established risk factors for MTSS injury and prevention of re-injury for this subject, are also discussed. Furthermore, the concept of preventing tibial stress fracture (TSF) by successfully managing acute MTSS, is presented. Lastly, a critical analysis of reliability of clinical assessment methodologies utilised with the subject is provided.

LEVEL OF EVIDENCE

Level 5; Single case report.

A preliminary study on the differences in male and female muscle force distribution patterns during squatting and lunging maneuvers

In the United States, 250,000 people tear their anterior cruciate ligament (ACL) annually with females at higher risk of ACL failure than males. By predicting muscle forces during low impact maneuvers we may be able to estimate possible muscle imbalances that could lead to ACL failure during highly dynamic maneuvers. The purpose of this initial study was to predict muscle forces in males and females similar in size and activity level, during squat and lunge maneuvers. We hypothesized that during basic low impact maneuvers (a) distribution of quadriceps forces are different in males and females and (b) females exhibit quadriceps dominance when compared to males. Two males and three females performed squatting and lunging maneuvers while electromyography (EMG) data, motion capture data, and ground reaction forces were collected. Nine individual muscle forces for muscles that cross the knee were estimated using an EMG-driven model. Results suggest that males activate their rectus femoris muscle more than females, who in turn activate their vastus lateralis muscle at their maximum flexion angle, and more their vastus medialis muscle when ascending from a squat. During the lunge maneuver, males used greater biceps femoris force than females, throughout the lunge, and females exhibited higher semitendinosus force. Quadriceps dominance was evident in both males and females during the prescribed tasks, and there was no statistical difference between genders. Understanding individual muscle force distributions in males and females during low impact maneuvers may provide insights regarding failure mechanisms during highly dynamic maneuvers, when ACL injuries are more prevalent.

Interrater and Intrarater Reliability of the Tuck Jump Assessment by Health Professionals of Varied Educational Backgrounds

Objective. The Tuck Jump Assessment (TJA), a clinical plyometric assessment, identifies 10 jumping and landing technique flaws. The study objective was to investigate TJA interrater and intrarater reliability with raters of different educational and clinical backgrounds. Methods. 40 participants were video recorded performing the TJA using published protocol and instructions. Five raters of varied educational and clinical backgrounds scored the TJA. Each score of the 10 technique flaws was summed for the total TJA score. Approximately one month later, 3 raters scored the videos again. Intraclass correlation coefficients determined interrater (5 and 3 raters for first and second session, resp.) and intrarater (3 raters) reliability. Results. Interrater reliability with 5 raters was poor (ICC = 0.47; 95% confidence intervals (CI) 0.33–0.62). Interrater reliability between 3 raters who completed 2 scoring sessions improved from 0.52 (95% CI 0.35–0.68) for session one to 0.69 (95% CI 0.55–0.81) for session two. Intrarater reliability was poor to moderate, ranging from 0.44 (95% CI 0.22–0.68) to 0.72 (95% CI 0.55–0.84). Conclusion. Published protocol and training of raters were insufficient to allow consistent TJA scoring. There may be a learned effect with the TJA since interrater reliability improved with repetition. TJA instructions and training should be modified and enhanced before clinical implementation.

Neuromuscular training to target deficits associated with second anterior cruciate ligament injury

SYNOPSIS

Successful return to previous level of activity following anterior cruciate ligament (ACL) reconstruction is not guaranteed, and the prevalence of second ACL injury may be as high as 30%. In particular, younger athletes who return to sports activities within the first several months after ACL reconstruction may be at significantly greater risk of a second ACL rupture compared to older, less active individuals. Significant neuromuscular deficits and functional limitations are commonly identified in athletes following ACL reconstruction, and these abnormal movement and neuromuscular control profiles may be both residual of deficits existing prior to the initial injury and exacerbated by the injury and subsequent ACL reconstruction surgery. Following ACL reconstruction, neuromuscular deficits are present in both the surgical and nonsurgical limbs, and accurately predict second-ACL injury risk in adolescent athletes. While second ACL injury in highly active individuals may be predicated on a number of modifiable and nonmodifiable factors, clinicians have the greatest potential to address the modifiable postsurgical risk factors through targeted neuromuscular interventions. This manuscript will (1) summarize the neuromuscular deficits commonly identified at medical discharge to return to sport, (2) provide the evidence underlying second-ACL injury risk factors, (3) propose a method to assess the modifiable deficits related to second-ACL injury risk, and (4) outline a method of intervention to prevent second ACL injury. The program described in this clinical commentary was developed with consideration for the modifiable factors related to second-injury risk, the principles of motor learning, and careful selection of the exercises that may most effectively modify aberrant neuromuscular patterns. Future validation of this evidence-based, late-phase rehabilitation program may be a critical factor in maximizing return-to-activity success and reduction of second-injury risk in highly active individuals.

LEVEL OF EVIDENCE

Therapy, level 5.

Anterior cruciate ligament- specialized post-operative return-to-sports (ACL-SPORTS) training: a randomized control trial

Background

Anterior cruciate ligament reconstruction (ACLR) is standard practice for athletes that wish to return to high-level activities; however functional outcomes after ACLR are poor. Quadriceps strength weakness, abnormal movement patterns and below normal knee function is reported in the months and years after ACLR. Second ACL injuries are common with even worse outcomes than primary ACLR. Modifiable limb-to-limb asymmetries have been identified in individuals who re-injure after primary ACLR, suggesting a neuromuscular training program is needed to improve post-operative outcomes. Pre-operative perturbation training, a neuromuscular training program, has been successful at improving limb symmetry prior to surgery, though benefits are not lasting after surgery. Implementing perturbation training after surgery may be successful in addressing post-operative deficits that contribute to poor functional outcomes and second ACL injury risk.

Methods/Design

80 athletes that have undergone a unilateral ACLR and wish to return to level 1 or 2 activities will be recruited for this study and randomized to one of two treatment groups. A standard care group will receive prevention exercises, quadriceps strengthening and agility exercises, while the perturbation group will receive the same exercise program with the addition of perturbation training. The primary outcomes measures will include gait biomechanics, clinical and functional measures, and knee joint loading. Return to sport rates, return to pre-injury level of activity rates, and second injury rates will be secondary measures.

Discussion

The results of this ACL-Specialized Post-Operative Return To Sports (ACL-SPORTS) Training program will help clinicians to better determine an effective post-operative treatment program that will improve modifiable impairments that influence outcomes after ACLR.

Trial registration

Randomized Control Trial NIH 5R01AR048212-07. ClinicalTrials.gov: NCT01773317

Augmented feedback supports skill transfer and reduces high-risk injury landing mechanics: a double-blind, randomized controlled laboratory study

BACKGROUND

There is a current need to produce a simple, yet effective method for screening and targeting possible deficiencies related to increased anterior cruciate ligament (ACL) injury risk.

HYPOTHESIS

Frontal plane knee angle (FPKA) during a drop vertical jump will decrease upon implementing augmented feedback into a standardized sport training program.

STUDY DESIGN

Controlled laboratory study.

METHODS

Thirty-seven female participants (mean ± SD: age, 14.7 ± 1.5 years; height, 160.9 ± 6.8 cm; weight, 54.5 ± 7.2 kg) were trained over 8 weeks. During each session, each participant received standardized training consisting of strength training, plyometrics, and conditioning. They were also videotaped running on a treadmill at a standardized speed and performing a repeated tuck jump for 10 seconds. Study participants were randomized into 2 groups and received augmented feedback on either their jumping (AF) or sprinting (CTRL) form. Average (mean of 3 trials) and most extreme (trial with greatest knee abduction) FPKA were calculated from 2-dimensional video captured during performance of the drop vertical jump.

RESULTS

After testing, a main effect of time was noted, with the AF group reducing their FPKA average by 37.9% over the 3 trials while the CTRL group demonstrated a 26.7% reduction average across the 3 trials (P < .05). Conversely, in the most extreme drop vertical jump trial, a significant time-by-group interaction was noted (P < .05). The AF group reduced their most extreme FPKA by 6.9° (pretest, 18.4° ± 12.3°; posttest, 11.4° ± 10.1°) on their right leg and 6.5° (pretest, 16.3° ± 14.5°; posttest, 9.8° ± 10.7°) on their left leg, which represented a 37.7% and 40.1% reduction in FPKA, respectively. In the CTRL group, no similar changes were noted in the right (pretest, 16.9° ± 14.3°; posttest, 14.0° ± 12.3°) or left leg (pretest, 9.8° ± 11.1°; posttest, 7.2° ± 9.2°) after training.

CONCLUSION

Providing athletes with augmented feedback on deficits identified by the tuck jump assessment has a positive effect on their biomechanics during a different drop vertical jump task that is related to increased ACL injury risk. The ability of the augmented feedback to support the transfer of skills and injury risk factor reductions across different tasks provides exciting new evidence related to how neuromuscular training may ultimately cross over into retained biomechanics that reduce ACL injuries during sport.

CLINICAL RELEVANCE

The tuck jump assessment's ease of use makes it a timely and economically favorable method to support ACL prevention strategies in young girls.

The influence of age on the effectiveness of neuromuscular training to reduce anterior cruciate ligament injury in female athletes: a meta-analysis

BACKGROUND

In female athletes, sports-related injuries to the anterior cruciate ligament (ACL) increase during adolescence and peak in incidence during the mid- to late teens. Although biomechanical investigations indicate that a potential window of opportunity exists for optimal timing for the initiation of integrative neuromuscular training (NMT) in young female athletes, the influence of the timing of initiation of these programs on the efficacy of ACL injury reduction has yet to be evaluated. HYPOTHESIS/ PURPOSE: The purpose of the current report was to systematically review and synthesize the scientific literature regarding the influence of age of NMT implementation on the effectiveness for reduction of ACL injury incidence. The hypothesis tested was that NMT would show a greater effect in younger populations.

STUDY DESIGN

Meta-analysis; Level of evidence 1a.

METHODS

Data were pooled from 14 clinical trials that met the inclusion criteria of (1) number of ACL injuries reported; (2) NMT program used; (3) female participants were included; (4) investigations used prospective, controlled trials; and (5) age of participants was documented or was obtainable upon contact with the authors. A meta-analysis with odds ratio (OR) was used to compare the ratios of ACL injuries between intervention and control groups among differing age categorizations.

RESULTS

A meta-analysis of the 14 included studies demonstrated significantly greater knee injury reduction in female athletes who were categorized in the preventive NMT group compared with those who were in the control group (OR: 0.54; 95% confidence interval [CI]: 0.35, 0.83). Lower ACL injuries in mid-teens (OR 0.28; CI: 0.18, 0.42) compared with late teens (OR 0.48; CI: 0.21, 1.07) and early adults (OR 1.01; CI: 0.62, 1.64) were found in participants undergoing NMT.

CONCLUSION

The findings of this meta-analysis revealed an age-related association between NMT implementation and reduction of ACL incidence. Both biomechanical and the current epidemiological data indicate that the potential window of opportunity for optimized ACL injury risk reduction may be before the onset of neuromuscular deficits and peak knee injury incidence in female athletes. Specifically, it may be optimal to initiate integrative NMT programs during early adolescence, before the period of altered mechanics that increase injury risk.

Current concepts for injury prevention in athletes after anterior cruciate ligament reconstruction

Ligament reconstruction is the current standard of care for active patients with an anterior cruciate ligament (ACL) rupture. Although the majority of ACL reconstruction (ACLR) surgeries successfully restore the mechanical stability of the injured knee, postsurgical outcomes remain widely varied. Less than half of athletes who undergo ACLR return to sport within the first year after surgery, and it is estimated that approximately 1 in 4 to 1 in 5 young, active athletes who undergo ACLR will go on to a second knee injury. The outcomes after a second knee injury and surgery are significantly less favorable than outcomes after primary injuries. As advances in graft reconstruction and fixation techniques have improved to consistently restore passive joint stability to the preinjury level, successful return to sport after ACLR appears to be predicated on numerous postsurgical factors. Importantly, a secondary ACL injury is most strongly related to modifiable postsurgical risk factors. Biomechanical abnormalities and movement asymmetries, which are more prevalent in this cohort than previously hypothesized, can persist despite high levels of functional performance, and also represent biomechanical and neuromuscular control deficits and imbalances that are strongly associated with secondary injury incidence. Decreased neuromuscular control and high-risk movement biomechanics, which appear to be heavily influenced by abnormal trunk and lower extremity movement patterns, not only predict first knee injury risk but also reinjury risk. These seminal findings indicate that abnormal movement biomechanics and neuromuscular control profiles are likely both residual to, and exacerbated by, the initial injury. Evidence-based medicine (EBM) strategies should be used to develop effective, efficacious interventions targeted to these impairments to optimize the safe return to high-risk activity. In this Current Concepts article, the authors present the latest evidence related to risk factors associated with ligament failure or a secondary (contralateral) injury in athletes who return to sport after ACLR. From these data, they propose an EBM paradigm shift in postoperative rehabilitation and return-to-sport training after ACLR that is focused on the resolution of neuromuscular deficits that commonly persist after surgical reconstruction and standard rehabilitation of athletes.

Effects of task-specific augmented feedback on deficit modification during performance of the tuck-jump exercise

CONTEXT

Anterior cruciate ligament (ACL) injuries are prevalent in female athletes. Specific factors have possible links to increasing a female athlete's chances of suffering an ACL injury. However, it is unclear if augmented feedback may be able to decrease possible risk factors.

OBJECTIVE

To compare the effects of task-specific feedback on a repeated tuck-jump maneuver.

DESIGN

Double-blind randomized controlled trial.

SETTING

Sports-medicine biodynamics center.

PATIENTS

37 female subjects (14.7 ± 1.5 y, 160.9 ± 6.8 cm, 54.5 ± 7.2 kg).

INTERVENTION

All athletes received standard off-season training consisting of strength training, plyometrics, and conditioning. They were also videotaped during each session while running on a treadmill at a standardized speed (8 miles/h) and while performing a repeated tuck-jump maneuver for 10 s. The augmented feedback group (AF) received feedback on deficiencies present in a 10-s tuck jump, while the control group (CTRL) received feedback on 10-s treadmill running.

MAIN OUTCOME MEASURES

Outcome measurements of tuck-jump deficits were scored by a blinded rater to determine the effects of group (CTRL vs AF) and time (pre- vs posttesting) on changes in measured deficits.

RESULTS

A significant interaction of time by group was noted with the task-specific feedback training (P = .03). The AF group reduced deficits measured during the tuck-jump assessment by 23.6%, while the CTRL training reduced deficits by 10.6%.

CONCLUSIONS

The results of the current study indicate that task-specific feedback is effective for reducing biomechanical risk factors associated with ACL injury. The data also indicate that specific components of the tuck-jump assessment are potentially more modifiable than others.

Intra and inter-tester reliability of the tuck jump assessment

OBJECTIVE

To assess the inter-tester and intra-tester reliability of the tuck jump test.

DESIGN

Repeated measures.

SETTING

University Human Performance laboratory.

PARTICIPANTS

Five male and 5 female athletes undertook the Tuck jump test which was then assessed by two independent assessors.

MAIN OUTCOME MEASURES

Score from the video assessment of the tuck jump test by two independent assessors on two separate occasions.

RESULTS

Average percentage of exact agreement (PEA) between the two testers across all scoring criteria for all subjects was 93% (range 80-100%). Both testers were in absolute 100% agreement in 5 out of 10 subjects for all of the scoring criteria. The kappa measure of agreement was k = 0.88 which is very good/excellent. The intra-tester PEA ranged 87.2%-100%, with kappa values of k = 0.86-1.0.

CONCLUSION

The study showed very good-excellent intra-tester and inter-tester reliability for both examiners when comparing their individual scores of the tuck jump test across two analysis sessions. These findings indicate that the proposed tuck jump assessment is reliable to identify abnormal landing mechanics.

The 2012 ABJS Nicolas Andry Award: The sequence of prevention: a systematic approach to prevent anterior cruciate ligament injury

BACKGROUND

ACL injuries are common, often devastating injuries that lead to short-term disability and long-term sequelae, many of which lack effective treatment, such as osteoarthritis. Therefore, prevention of ACL injury is currently the only effective intervention for these life-altering sequelae, while much of the literature has a rehabilitative focus.

QUESTIONS/PURPOSES

The primary long-term purpose of our multidisciplinary collaborative research team has been to develop ACL injury prevention programs by determining which factors related to ACL injury should be altered, followed by how and when they should be altered.

METHODS

Our primary study objectives were to determine: (1) modifiable risk factors; (2) how these factors can best be modified; and (3) when is the best time to diminish these risk factors. Throughout the course of various studies, we determined the modifiable factors related to increased ACL injury risk. Our research team then focused on exploring numerous ways to augment these factors to maximize prevention efforts. We developed a sequence of prevention models that provide a framework to monitor progress toward the ultimate goal of preventing ACL injuries.

RESULTS

The modifiable factors shown in our work include biomechanical and neuromuscular functionality. When targeted in physical training, we have determined that these factors can be enhanced to effectively aid in the prevention of ACL injuries. Preliminary data have shown that childhood and early adolescence may be valuable periods to implement such training.

CONCLUSIONS

Current evidence has led to the evolution of clinical assessment tools for high-risk athletes and interventions for large populations and specific high-risk individuals. Targeted intervention implemented at the specified developmental stage of highest risk may be the final step toward the maximal reduction of ACL injury risk in young athletes.

Comparison of landing knee valgus angle between female basketball and football athletes: possible implications for anterior cruciate ligament and patellofemoral joint injury rates

OBJECTIVE

To evaluate landing strategies of female football and basketball athletes with relation to possible injury mechanisms and disparity in injury.

DESIGN

Descriptive laboratory study.

PARTICIPANTS

52 female football players and 41 female basketball players.

MAIN OUTCOME MEASURES

Frontal plane projection angle (FPPA) was measured during the single leg land (SLL) and drop jump (DJ) screening tasks.

RESULTS

2 × 2 × 2 mixed factorial ANOVA showed significant main effects were observed for sport, whilst significant interaction effects were seen between sport and task. Females in both sports exhibited significantly greater FPPA values during the SLL task than the DJ task (p < 0.001). Basketball players demonstrated significantly greater FPPA values during SLL than football players (p < 0.001), whilst no differences were found between sports in the DJ task (p = 0.328).

CONCLUSION

Female basketball players display greater FPPA values during unilateral landing tasks than female football players which may reflect the greater ACL injury occurrence in this population. Injury prevention programs in these athletes should incorporate unilateral deceleration and landing tasks and should consider the specific injury mechanisms in each sport.

The influence of core musculature engagement on hip and knee kinematics in women during a single leg squat

PURPOSE/BACKGROUND

Excessive frontal plane motion and valgus torques have been linked to knee injuries, particularly in women. Studies have investigated the role of lower extremity musculature, yet few have studied the activation of trunk or "core" musculature on hip and knee kinematics. Therefore, this study evaluated the influence of intentional core engagement on hip and knee kinematics during a single leg squat.

METHODS

Participants (n = 14) performed a single leg squat from a 6 inch step under 2 conditions: core intentionally engaged (CORE) and no intentional core engagement (NOCORE). Participants were also evaluated for core activation ability using Sahrmann's model, and the resulting scores were used to divide participants into low (LOWCORE) and high scoring (HIGHCORE) groups. All trials were captured using 3-D motion analysis, and data were normalized for height and time. Paired t-tests and repeated measures, mixed model MANOVAs were used to assess condition and group differences.

RESULTS

The CORE condition, compared to NOCORE, was characterized by smaller right [t(13) = 3.03, p = .01] and left [t(13) = 3.04, p = .01] hip frontal plane displacement and larger knee flexion range of motion [t(13) = 3.08, p = .009]. Subsequent MANOVAs and follow-up analyses revealed that: (1) the CORE condition demonstrated smaller right and left hip medial-lateral displacement in the LOWCORE group (p = .001), but not in the HIGHCORE group; (2) the CORE condition showed larger overall knee flexion range of motion across LOWCORE and HIGHCORE groups (p = .021); and (3) the HIGHCORE group exhibited less knee varus range of motion across CORE and NOCORE conditions (p = .028).

CONCLUSIONS

Intentional core activation influenced hip and knee kinematics during single leg squats, with greater positive effect noted in the LOWCORE group. These findings may have implications for preventing and rehabilitating knee injuries among women.

LEVEL OF EVIDENCE

2B, Cohort laboratory study, mixed model design.

Does an in-season only neuromuscular training protocol reduce deficits quantified by the tuck jump assessment?

BACKGROUND

Female athletes are 4–6 times more likely to suffer an ACL injury than males in comparable sports. A link between landing biomechanics and ACL injury has led to the development of injury prevention focused training protocols. It is often difficult to measure the protocols’ efficacy of different protocols on reduction of ACL injury-related factors.

PURPOSE

The purpose of this study was to test the effects of in-season neuromuscular training on a field-based evaluation used to help identify athletes at risk for ACL injuries. The hypothesis was that the ACL injury prevention training program included with an in-season soccer program would demonstrate increased improvement in the Tuck Jump Assessment (TJA) scores at post-season follow-up testing relative to standard in-season soccer training.

METHODS

Forty-nine female soccer players were tested with TJA before and after participation in either in-season injury prevention training (IN) or standard in-season soccer training (CTRL). Participants were filmed performing the TJA with digital video cameras and scored by two separate raters, each viewing randomized videos. The groups received neuromuscular training synthesized from previous protocols demonstrated to decrease ACL injury. A mixed design (2X2; group by time) repeated measures ANOVA was used to test the interaction and main effects of group (ACL intervention training in-season vs. standard soccer in-season training) and time (pre vs. post-season) on dynamic TJA scores.

RESULTS

There was a significant main effect of time on TJA score (p=0.04) for athletes measured at pre- and post-season. The IN group reduced measured landing and jumping deficits from 5.4 ± 1.6 to 4.9 ± 1.0 points following training. CTRL showed a 14% reduction in TJA deficit points following the soccer season.

CONCLUSIONS

The tested hypothesis that the in-season ACL intervention training can be utilized to reduce measured TJA deficits above and beyond a standard in-season soccer protocol was not supported. Future research is warranted to determine if a combination of intensive pre-season and reduced in-season maintenance training is optimal for improvement of dynamic movement biomechanics during the TJA and ultimately preventing ACL injuries.