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ACL Injury Risk Factors, Screening Tests, and Prevention Programs

 

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ACL Injury Risk Factors, Screening Tests, and Prevention Programs

ACL Injury

Developed by: Michael Irr, SPT, CSCS-NSCA

Background

My Critically Appraised Topic (CAT) in our Evidenced-Based Practice II (EBP II) was on the effectiveness of prevention programs in reducing the incidence of anterior cruciate ligament (ACL) ruptures in female high school basketball players.  Full results of my CAT can be found here: My Final CAT.  Briefly, I found the current evidence to show that an ACL prevention program implemented in the pre-season and season focusing on neuromuscular components (plyometric, strength, agility, and balance exercise) can reduce the risk, rate, and/or incidence of ACL injuries in female high school basketball players.1–3

After completing my CAT, I was interested in deepening my knowledge of ACL injuries and wanted to bring this information to sports medicine professionals in hopes of promoting better care for high school athletes. I decided to investigate the literature in two different areas: risk factors for ACL injury and potential screening tests to identify these risk factors.

Statement of Need

While high school athletics provides a great medium for improving physical fitness, mental health, and academic performance, it can also lead to increased risk of injury.4,5 Amongst high school athletes, non-contact mechanisms make up 75-95% of ACL ruptures.6,7  More than any other injury, ACL ruptures lead to the end of an athletic season and subsequent reconstructive surgery. While surgery is currently the best treatment option for young athletes to return to sport, the injury can negatively affect their psychology8 and increases the likelihood of future orthopedic issues.9 Also, the economic burden placed on patients, families, and the medical system can be substantial.10  Based on this information, any help in reducing the number of these injuries would benefit our young athletes.  I believe risk factor identification through screening tests and injury prevention programs could help reduce this type of injury and sports medicine professionals, like physical therapists and athletic trainers, are in prime position to help promote their use in high schools.

Project Overview

For my capstone, I wrote a scholarly paper on ACL injury mechanisms and risk factors, with a primary focus on modifiable risk factors that may be appropriate for screening tests.  These modifiable risk factors include general joint hypermobility, neuromuscular control, hamstring strength, and fatigue.  I proposed potential clinical or field screening tests for identifying some of these modifiable risk factors and supported their use with available evidence.  Unfortunately, despite a plethora of research on risk factors, evidence is scant for screening tests.  The screens I investigated were the Beighton score, Functional Movement Screen, Landing Error Score System (LESS), Tuck Jump Assessment, and Nordic Hamstring Test.11–15  In my paper I described their strengths, weaknesses, and areas of future research.  Lastly, I briefly outlined some literature on prevention programs including key components, guidelines, and factors all programs should consider. My scholarly paper can be viewed here: My Scholarly Paper.

To accompany this paper, I created a presentation geared towards sports medicine professionals, primarily those who work in clinics or at high schools. I was fortunate to be able to speak to a group of ten high school athletic trainers in the greater Charlotte area.  I’ve created a Voicethread of my presentation that can be found here: My Presentation Voicethread.  I provided a handout to the athletic trainers on scoring criteria for the LESS and Tuck Jump Assessment because it was too much to include on my presentation slides.  It can be found here: My Presentation Handout. Lastly, I provided an evaluation form for my presentation and received feedback from the athletic trainers in the audience.  The evaluation form and summary of presentation feedback can be found here: My Capstone Presenter Evaluation Form and Summary Feedback.

Self-Assessment

This Capstone project involved a lot of information in different areas of ACL injury research, including risk factors, screening tests, and prevention programs.  It was a challenge to sift through all of the evidence, but experiences in Evidence-Based I & II were helpful.  These skills will be beneficial as I become a clinician in the field.  While it may have been better to focus on one specific area for my Capstone , risk factors, screening tests, and prevention programs are related to each other in a such a way that it would have been impossible to discuss one independently of the others.  Comprehensively appraising all of this information for my scholarly paper was a significant challenge, but the skill of synthesizing the results will be beneficial to me as a clinician.  With a lack of ACL screening test options, I found myself having to make clinical decisions about tests that seemed logical and supported by evidence.  This was an interesting process because it challenged my clinical reasoning and forced me to think critically and creatively.  For example, the Nordic Hamstring Test was developed for screening hamstring strains, but I feel there is some applicability to ACL screening based on my research of risk factors.  The need for more evidence of screening tests makes me want to be involved with research in this area and it may be something I pursue upon graduation.  The process of completing the project was challenging with all of the other needs of 3rd year.  Setting deadlines and constant communication with my committee helped tremendously.  Having an oral presentation allowed me to test my public speaking skills, which is something I’ve always wanted to improve.  In the future, I hope to be an educator in some capacity, so feedback from my evaluation helped me realize more areas I could improve in public speaking going forward.  Overall, this Capstone project allowed me to grow as an appraiser of evidence and a synthesizer of information.  I’m proud of how I developed during the process and look forward to similar challenges over the course of my career.

Acknowledgements

First, I’d like to thank Dr. Mike Gross for helping me find direction for my capstone. His guidance helped me narrow my vast interests in ACL injuries to a manageable topic for a paper and presentation. Additionally, I’d like to thank Michael Rosenberg and Spencer Elliott from Novant Rehabilitation. Michael is a physical therapist who has been a constant resource for me in Charlotte and provided important feedback on my paper and presentation. Spencer is an athletic trainer who supervises a number of athletic trainers in the greater Charlotte area and helped coordinate of my presentation, in addition to providing feedback.

References

For a full list of references used for my capstone, see here: My Capstone References

  1. LaBella CR, Huxford MR, Grissom J, Kim K-Y, Peng J, Christoffel KK. Effect of neuromuscular warm-up on injuries in female soccer and basketball athletes in urban public high schools: cluster randomized controlled trial. Arch Pediatr Adolesc Med. 2011;165(11):1033–40. doi:10.1001/archpediatrics.2011.168.
  2. Sugimoto D, Myer GD, McKeon JM, Hewett TE. Evaluation of the effectiveness of neuromuscular training to reduce anterior cruciate ligament injury in female athletes: a critical review of relative risk reduction and numbers-needed-to-treat analyses. Br J Sports Med. 2012;46(14):979–88. doi:10.1136/bjsports-2011-090895.
  3. Yoo JH, Lim BO, Ha M, et al. A meta-analysis of the effect of neuromuscular training on the prevention of the anterior cruciate ligament injury in female athletes. Knee Surg Sports Traumatol Arthrosc. 2010;18(6):824–30. doi:10.1007/s00167-009-0901-2.
  4. Ardoy DN, Fernández-Rodríguez JM, Jiménez-Pavón D, Castillo R, Ruiz JR, Ortega FB. A Physical Education trial improves adolescents’ cognitive performance and academic achievement: the EDUFIT study. Scand J Med Sci Sports. 2014;24(1):e52–61. doi:10.1111/sms.12093.
  5. Dohle S, Wansink B. Fit in 50 years: participation in high school sports best predicts one’s physical activity after age 70. BMC Public Health. 2013;13:1100. doi:10.1186/1471-2458-13-1100.
  6. Alentorn-Geli E, Myer GD, Silvers HJ, et al. Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors. Knee Surg Sports Traumatol Arthrosc. 2009;17(7):705–29. doi:10.1007/s00167-009-0813-1.
  7. Dai B, Herman D, Liu H, Garrett WE, Yu B. Prevention of ACL injury, part I: injury characteristics, risk factors, and loading mechanism. Res Sports Med. 2012;20(March 2015):180–97. doi:10.1080/15438627.2012.680990.
  8. Ardern CL, Osterberg A, Tagesson S, Gauffin H, Webster KE, Kvist J. The impact of psychological readiness to return to sport and recreational activities after anterior cruciate ligament reconstruction. Br J Sports Med. 2014;48(22):1613–9. doi:10.1136/bjsports-2014-093842.
  9. Ajuied A, Wong F, Smith C, et al. Anterior Cruciate Ligament Injury and Radiologic Progression of Knee Osteoarthritis: A Systematic Review and Meta-analysis. Am J Sports Med. 2013:1–11. doi:10.1177/0363546513508376.
  10. Swenson DM, Collins CL, Best TM, Flanigan DC, Fields SK, Comstock RD. Epidemiology of Knee Injuries among U.S. High School Athletes, 2005/2006-2010/2011. Med Sci Sports Exerc. 2013;45(3):462–469. doi:10.1249/MSS.0b013e318277acca.
  11. Myer GD, Ford KR, Paterno M V, Nick TG, Hewett TE. The effects of generalized joint laxity on risk of anterior cruciate ligament injury in young female athletes. Am J Sports Med. 2008;36(6):1073–1080. doi:10.1177/0363546507313572.
  12. Cook G. Movement. Santa Cruz, CA: On Target Publications; 2011.
  13. Padua D a, Marshall SW, Boling MC, Thigpen C a, Garrett WE, Beutler AI. The Landing Error Scoring System (LESS) Is a valid and reliable clinical assessment tool of jump-landing biomechanics: The JUMP-ACL study. Am J Sports Med. 2009;37(10):1996–2002. doi:10.1177/0363546509343200.
  14. Myer GD, Ford KR, Hewett TE. Tuck Jump Assessment for Reducing Anterior Cruciate Ligament Injury Risk. Athl Ther Today. 2008;13(5):39–44. doi:10.1055/s-0029-1237430.Imprinting.
  15. Sconce, E. Jones P. The validity of the Nordic hamstring lower as a field-based assessment of eccentric hamstring strength. J Sport Rehabil. 2015;24(1):13–20.

 

4 Responses to “ACL Injury Risk Factors, Screening Tests, and Prevention Programs”

  1. Michael Irr

    Hi Pat,

    Thank you for your kind words and questions. I’ve sectioned out my responses to your questions below.

    Adaptation of Info to Sport
    First, it’s important to perform a “needs analysis” for each sport that analyzes biomechanics/movement of the sport, physiological requirements, and injury epidemiology. From there, batteries of performance and/or risk factor screening tests, and orthopedic assessments can be created to target these findings. The information presented in my capstone may be most relevant to any sport with high incidence of ACL ruptures, like basketball or soccer. Certainly, an ACL injuries are less likely in baseball, but the information could still be relevant. Therefore, I think the information can be applied as it is relevant to the sport or athlete’s needs.

    Coach or Parent Implementation?
    As far as I can tell, there isn’t any research on ACL education for parents. As mentioned in my Capstone, compliance with prevention programming is critical to the success of the program. We learned from Frank et al (2014) that injury prevention education can change a coach’s attitude towards implementing prevention programming, but this does not appear to translate to high levels of implementation compliance.(1) Obviously this is unfortunate. I think parent education may be a great addition to any sports injury prevention program, but would that translate to compliance? Possibly in the off-season, when parents have more control over their children’s activities and can send them for specific training. I think the best advocators of program compliance can come from sports medicine professionals like ATCs and physical therapists. In my opinion, coaches want to worry about X’s and O’s (skill and strategy development) and winning, so we have to promote prevention programs in a way that may help them towards that goal. One way to do that may be to promote the performance enhancing benefits of these programs in addition to keeping their athletes healthy.(2) Sports medicine professionals are the ones who should be pushing for prevention programming and finding ways to work with both coaches and parents to find the best opportunities for their athletes. It’s an extremely challenging problem to solve, but I think hard work and persistence can help move us in the right direction.

    Exercises to Decrease Risk of Injury
    I think the types of exercises you can use are limitless, with plyometric and strength training of the lower extremity and dynamic postural control being very important. I have a tendency to divide lower extremity patterns into bilateral symmetrical (squat), bilateral asymmetrical (lunge), and unilateral stance (single leg). Then challenge the athlete in all three planes of motion with high-risk athletic movements (for example jumps forward, side to side, and rotating). Additionally, I think feedback is critical to help with motor learning during these exercises.(3) Two articles that may help are Gokeler et al (2013) (3) and Benjaminse et al (2015) (4), in which the authors provide feedback techniques to enhance motor learning.

    References
    1. Frank BS, Register-Mihalik J, Padua D a. High levels of coach intent to integrate a ACL injury prevention program into training does not translate to effective implementation. J Sci Med Sport. 2014. doi:10.1016/j.jsams.2014.06.008.
    2. Joy EA, Taylor JR, Novak MA, Chen M, Fink BP, Porucznik CA. Factors influencing the implementation of anterior cruciate ligament injury prevention strategies by girls soccer coaches. J Strength Cond Res. 2013;27(8):2263–9. doi:10.1519/JSC.0b013e31827ef12e.
    3. Gokeler A, Benjaminse A, Hewett TE, et al. Feedback techniques to target functional deficits following anterior cruciate ligament reconstruction: implications for motor control and reduction of second injury risk. Sports Med. 2013;43(11):1065–74. doi:10.1007/s40279-013-0095-0.
    4. Benjaminse A, Gokeler A, Dowling A V., et al. Optimization of the Anterior Cruciate Ligament Injury Prevention Paradigm: Novel Feedback Techniques to Enhance Motor Learning and Reduce Injury Risk. J Orthop Sport Phys Ther. 2015;45(3):170–182. doi:10.2519/jospt.2015.4986.

    Reply

  2. Michael Irr

    Dr. Gross,

    Thank you for your constructive feedback – it is greatly appreciated. I agree with you that depth was an issue for my Capstone. In retrospect, I wish I had focused on one of the following: modifiable neuromuscular risk factors or screening tests or prevention program components. I think this would have improved the depth and quality of my Capstone given semester time constraints.

    Responses to Questions:

    Question 1: The assumption is that excessive rotational traction from shoe-surface interactions may precipitate knee injuries. The study often cited is a two-part prospective study by Lambson et al (1996). They demonstrated shoes with an Edge design were associated with increased shoe-to-turf torsional resistance (Nm) and increased injury rate amongst high school football players.1 The Edge design was described as having “longer irregular cleats placed at the peripheral margin of the sole with a number of smaller pointed cleats positioned interiorly.”(1 p.156) This was compared to flat cleats, screw-in cleats, and pivot disk cleats, all of which showed no significant difference in torsional resistance or injury rate between them. All shoes had cleats that were 0.5 inches or less in height. This was reported in systematic reviews by Alentorn-Geli (2009) (2) and Acevedo (2014) (3).

    A more recent study by Villwock et al (2009) using a similar study design as Labmson et al, showed no significant differences between cleat design (including the “edge” design” and rotational traction.4 However, shoes with cleats created significantly greater rotational traction than turf (non-cleated) shoes. (4) In considering this more recent data, it’s possible that changes in shoe design may have decreased the effect cleat-surface interactions.

    Question 2: It has been suggested that variations in structure and materials of turf, the running speed of players, or the coefficient of friction between surface and shoe are responsible for an increased injury rate on artificial surfaces. The study by Villwock et al (2009) demonstrated both FieldTurf and AstroTurf result in significantly greater rotational stiffness and peak torque through a lower extremity in a cleated condition compared to natural grass.(4) Rotational stiffness is defined as “the slope of the torque versus rotation data in a predefined angular range” and is said to be “a more sensitive indicator of the mechanical interaction between different shoe-surface combinations than peak torque.” (4 p519) Increased forces from artificial turf could increase the risk of ACL rupture.

    Question 3: Beynnon et al (2014) showed that in general, there is an increased relative risk playing sports in college compared to high school.(5) Identifying why is challenging because it’s likely a number of factors are involved. I believe college sport is more intense, requiring higher and more rapid force production during high-risk athletic movements. It’s possible some of these athletes are unprepared for the rigors of college athletics. In a survey of collegiate level strength and conditioning coaches, Wade et al (2014) found a major issue for incoming freshman athletes is that they lack physical qualities, specifically lower extremity strength and flexibility, and mental toughness.(6) Additionally, more intense training time and psychological stress could increase physical and mental fatigue and subsequently increase the risk of injury. Vetter and Symonds (2010) found college athletes train at moderate or high intensity levels 4.5 days per week, resulting in significant physical and mental exhaustion amongst both men and women.(7) I think there is a lot of information to learn about college athletics and many factors are likely to be involved, but physical readiness, increased intensity of competition, and increased risk of fatigue due to physical and mental exhaustion could play a role in increased ACL injuries at the college level.

    Question 5: I should have said the following in regards to quad and hamstring co-activation: Hewett et al (2006) report in their review of ACL injuries in female athletes that co-activation of the hamstrings and quads protect against excessive anterior drawer of the tibia, knee abduction, and dynamic lower extremity valgus.(8) In order to create net flexor moments about the knee in the presence of lower recruitment or weakness in hamstrings, the quadriceps would have to reduce their activation to allow motion.(8) They go on to say that “deficits in strength and activation of the hamstrings directly limit the potential for muscular co-contraction to protect ligaments.”8(303) With high hamstring recruitment, the quadriceps can also highly activate, resulting in internal knee flexor moments. A study by Baratta et al (1998), showed reduced hamstring activity diminished the total amount of stabilizing forces available, which exposed the ligaments to loading forces.(9) I should have said reduced hamstring strength or activation decreases the potential for muscular co-contraction about the knee during sporting activity, which could expose the ligaments to increased forces if the hamstrings cannot oppose the quadriceps.

    Mike, thank you again for your feedback. I appreciate all of the support you’ve provided me during the three years I’ve attended UNC.
    Take care,
    Mike

    References
    1. Lambson RB, Barnhill BS, Higgins RW. Football cleat design and its effect on anterior cruciate ligament injuries. A three-year prospective study. Am J Sports Med. 1996;24(2):155–159. doi:10.1177/036354659602400206.
    2. Alentorn-Geli E, Myer GD, Silvers HJ, et al. Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors. Knee Surg Sports Traumatol Arthrosc. 2009;17(7):705–29. doi:10.1007/s00167-009-0813-1.
    3. Acevedo RJ, Rivera-Vega A, Miranda G, Micheo W. Anterior cruciate ligament injury: identification of risk factors and prevention strategies. Curr Sports Med Rep. 2014;13(3):186–91. doi:10.1249/JSR.0000000000000053.
    4. Villwock MR, Meyer EG, Powell JW, Fouty AJ, Haut RC. Football playing surface and shoe design affect rotational traction. Am J Sports Med. 2009;37(3):518–525. doi:10.1177/0363546508328108.
    5. Beynnon BD, Vacek PM, Newell MK, et al. The Effects of Level of Competition, Sport, and Sex on the Incidence of First-Time Noncontact Anterior Cruciate Ligament Injury. Am J Sports Med. 2014. doi:10.1177/0363546514540862.
    6. Wade S, Pope Z, Simonson S. How Prepared Are College Freshmen Athletes for the Rigors of College Strength and Conditioning? A Survey of College Strength and Conditioning Coaches. J Strength Cond Res. 2014;28(10):2746–2753.
    7. Vetter RE, Symonds ML. Correlations between injury, training intensity, and physical and mental exhaustion among college athletes. J Strength Cond Res. 2010;24(3):587–596. doi:10.1519/JSC.0b013e3181c7c2eb.
    8. Hewett TE, Myer GD, Ford KR. Anterior cruciate ligament injuries in female athletes: Part 1, mechanisms and risk factors. Am J Sports Med. 2006;34(2):299–311. doi:10.1177/0363546505284183.
    9. Baratta R, Solomonow M, Zhou BH, Letson D, Chuinard R, D’Ambrosia R. Muscular coactivation. The role of the antagonist musculature in maintaining knee stability. Am J Sports Med. 1988;16(2):113–122. doi:10.1177/036354658801600205.

    Reply

  3. Mike Gross

    Michael- You did a very nice job on the capstone. The paper, voicethread, and handout were well done. I would have like to have seen you describe and explain some of the content in greater depth. For example:
    1. Why do longer cleats and a greater number of cleats pose increased risk for ACL injury?
    2. The same question could be posed for your discussion of the different types of grass playing surfaces.
    3. Why is risk of injury greater for college athletes compared with high school athletes?
    4. You seem to have some confusion between the concepts of tensile stress and shear stress as it relates to ACL injury. Increased quadriceps activation in positions of slight knee flexion increases the anteriorly directed shear FORCE imposed on the proximal tibia relative to the distal femur. As the tibia translates anteriorly on the femur, this imposes increased tensile stress on the ACL.
    5. I would also like to understand more clearly your assertion that the quadriceps cannot activate properly in the absence of proper hamstring muscle activation.
    6. Finally, you did a nice job laying out risk factors and screening tests. Trying to go into training programs was really beyond the scope of the project, but as long as you were going to throw it into the paper and voicethread, you might have mentioned training programs that try to target landing, cutting, and deceleration movement strategies since these were heavily detailed by you as modifiable risk factors.

    All in all, you did a very nice job on this project and have set the stage to go further in your exploration of training programs should you so desire. Best regards, Mike Gross

    Reply

  4. Pat McNamara

    Mike you’ve really done a fantastic job of providing a continuum of care approach to this topic. By that I mean, exploring before the injury, preventing the injury, rehabbing the injury, and preventing a secondary injury. A few questions you will undoubtedly encounter in your career (if you haven’t already), is how to adapt your information to athletes that become single sport dominant (particularly at a young age). A sport like baseball creates disparities in strength and movement quality/range.

    Another question to consider is how to design programs that coaches will implement. Has anyone targeted parents, rather than coaches for an educational seminar? Coaches are ultimately retained on their W-L record. Losing an athlete like Adrian Peterson or Marcus Lattimore to an ACL injury not only hurts the athlete, but also the coach’s chances of a successful season.

    Lastly you discussed some of the screening components/outcome measures for seeing who is at risk. What kinds of exercises have you found that may decrease their risk? OKC/CKC hamstring dominant exercises? Single leg mobility tasks? I’m reading through a few ACL prevention papers now and will comment back on some of the resistance training to change an individual’s movement pattern in a cutting task as I finish!

    Reply

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