What are the best prevention interventions for anterior cruciate ligament (ACL) injury in female athletes?
The purpose of this wiki was to review literature to identify prevention interventions that significantly reduce the risk of ACL injuries in female athletes. The interventions reviewed to prevent ACL injuries included pre-participation screening, protective knee bracing, footwear and surfaces, and intervention programs.


Screen Shot 2016-04-20 at 11.16.58 AM.png


Evidence
Databases: PubMed, Google Scholar
Search terms: ACL, Anterior Cruciate Ligament, knee, prevention, injury, intervention, brace, external device, female athletes
Boolean terms: AND
Levels of Evidence: Level I and II studies

Foreground Information
ACL tears are estimated to affect 200,000 people annually. These injuries are commonly seen in people participating in physically challenging activities such as basketball, soccer and gymnastics. Seventy percent of ACL tears happen without contact with another person or structure.1 ACL tears commonly happen with sudden deceleration, hyperextension, twisting, or valgus stress on the knee. According to the American Physical Therapy Association, ACL injuries are 4-6 times more common in females. They have a 5 time greater chance of sustaining an ACL tear compared to men when suffering the same landing and pivoting forces.2 Some female athletes participate in interventions focusing on preventing an ACL tear by strengthening surrounding muscles, increasing neuromuscular strength, and incorporating plyometric exercises while other female athletes rely on a knee brace to prevent injury. Still, there are many female athletes who do not focus on ACL injury prevention. This wiki evaluates research to establish the effectiveness of prevention interventions versus external assistive devices or no intervention.


external image 65yqKIe8n-HzQ2MFgKDNxsvOwKE1OWBTDLKdusVWGV4iOH1JkPlfmf9HplgnifHHNTWLzJxKUNqu5y0aw7nC5whfel-JWTakiAOxAgRHXZ1NoDeXsqKqO2GSI32J2viDlhj5e08h
external image efWPEoPZ6HrGFr4mYFPSuezuYxl9OUIgeUnHeIV0N9-XlpBn9Wex3e5tA4X3flzIiz94ph0ZYkxJYqErYpCnLxbFkvA46bAnmtlKaicCOO6Hn1w3jfX1mTRqscOQXgESYfYuyOKf


ACL Mechanism Video:
__https://www.youtube.com/watch?v=O0KegyyvfFM__

ACL Injury Treatment Prevention in Females by Dr. Martha Murray and Dr. Greg Myer
https://www.youtube.com/watch?v=CMy7qup3EIg


PRE-PARTICIPATION SCREENING
Athletes are deemed ‘low-risk’ if they exhibit a ‘good movement pattern’, characterized by no knee valgus at initial foot contact, no knee valgus displacement from initial contact to maximum knee flexion, landing with greater than 30 degrees of knee flexion, undergoing greater than 30 degrees of knee flexion displacement during landing, and exhibiting minimal to no sound upon landing. In contrast, if they exhibit a ‘poor movement pattern’, characterized by moderate to large knee valgus position at initial foot contact, moderate to large knee valgus displacement from initial contact to maximum knee flexion, landing with less than 30 degrees of knee flexion, undergoing less than 30 degrees of knee flexion from initial contact to maximum knee flexion, and exhibiting loud sound upon landing.2

SINGLE LEG HOP AND HOLD TEST
  • Procedure
    • Subject begins in single leg stance. Subject will perform a single leg hop forward and hold the landing in a single leg stance.
  • Assessment
    • Ability to maintain balance
    • Stabilize hip level
    • Valgus deviation at knee
    • Sup/Pro at foot
  • Evidence
    • Functional hop tests are used by clinicians to assess lower extremity muscular strength, normal limb symmetry, the integrated effect of neuromuscular control, and the ability to perform activities that require knee stability. Cates et al found that hop tests are inexpensive to administer and utilize more functional athletic movements when compared to isokinetic lower extremity muscle testing.3


external image x1se-tEyaLw2lNeDd7C3f42LxknrXSqy-m0UoN9DQAyuAZ2SD3wGRvBPvAciGbrw6ntk352vO-pbbm856U9ryZQjjjnFHsOza8kM36M6W3QXuMc89rPblXcwNmXhtW8AwPM2Rd2K


DROP VERTICAL JUMP (DVJ) TEST:
  • Procedure:
    • Subject stands on 31 cm box with feet 35 cm apart. Drop down off of box and immediately perform max vertical jump with both arms raised. Land on both legs. Repeat 3 times.
  • Assessment:
    • Both feet hit ground at same time on initial contact
    • pronation on initial contact
    • medial knee motion (valgus)
  • Evidence:
    • Medial knee motion may be related to an overall dynamic knee valgus. This includes femoral adduction, femoral internal rotation in relation to hip, tibial external rotation in relation to femur with or without foot pronation.4
    • The DVJ test has a high inter-rater reliability (0.92), including physicians and allied health professionals. For identifying subjects as “high risk”, the DVJ test was found to have a sensitivity of 63.06% and a specificity of 82.81%. Reducing the screening cutoff to also identify subjects at “medium risk” increased the sensitivity to 95.04%, but decreased specificity to 46.07%.5


external image vpm7Yk70Hsi772uDue9u9ahMUWucAnOMkwcsgghWBfJ3XlkaSM2tXGTGfi1yvVC-ogSw2HTz2oW2fY9NKDXmfYXrcyQ7YUNO9xaM5E_CH4sGpPTQTnqHsSR-MIUriAu_xC8hVxfn



SINGLE LEG SQUAT (SLS)
  • Procedure:
    • Start in single leg stance and perform SLS with hands on hips or out to side to 45-60˚ of knee flexion. Repeat 10x.
  • Assessment:
    • Pronation or supination of foot
    • knee valgus
    • hip internal rotation
    • ability to maintain balance
    • extension or flexion of the trunk
    • ability to perform entire set of 10 reps.
  • Evidence:
    • SLS used to replicate common athletic positions and check body control over a planted leg. It is used to screen for inadequate hip strength and/or trunk control. Females are prone to decreased hip control when squatting down and coming up from a squat, causing knee valgus.6



1400669179820.jpg
1400669179820.jpg


TIBIOFEMORAL ALIGNMENT
  • Procedure
    • MRI used to assess tibiofemoral alignment at 3 landing positions during DVJ test.
  • Assessment
    • Assessing tibial slope relative to the femur in provocative and exaggerated positions
  • Evidence
    • In the provocative and exaggerated positions, the tibial slope relative to the femur was directed significantly more inferior to superior. In contrast, as the limb transitioned more towards safe positions, the tibiofemoral joint point of contact was significantly closer to the femoral sulcus point and to the most anterior point of the circular posterior portion of the lateral femoral condyle. Researchers concluded that the anatomical alignment and contact characteristics during provocative positions places the knee at a higher risk for non-contact anterior cruciate ligament injury.7

external image nB4AV_cEQ4H4mX_SkjB-ZZXSMczEBlAph5hTmY1jN2CqGhJShL5wSM4fytytzEjrHe-qBysO6PTvOzogXFs-27KeLYfdb5fv4oKvwlIm_zAXHR9GF7UD-gq5-pKNzxwcUwjOveF-external image cTmm3C_INJkr6_EilxiCD3th1Fhv4fRRWh4hepYL2dGQXmc9OrSwOMCbyaSgyGzR_G_1YDN2sTxvBnJLrNG920k1_Egp6nRj9XGZGQT54-qOptIkxYEiJMdcay4ATi-HTd8iw-Id

PROTECTIVE KNEE BRACING
Screen Shot 2016-04-19 at 1.25.04 PM.png

A knee brace that resists internal tibial rotation increased the compressive load required to sustain an ACL injury anywhere from 10-62%. The compressive forces were applied at three different angles of flexion, 22˚, 37˚, and 52˚. This study was done on cadavers so other muscular groups were not able to provide their normal protection. While the restraint of rotation protected the ACL, it resulted in other injuries to cartilage and bone.8

According to another study published in the Iranian Journal of Radiology in 2015, functional knee braces do not significantly limit anterior or posterior tibiofemoral translation during single leg lunges compared to lunges performed without a brace. This study used fluoroscopic imaging, similar to a continuous X-ray, to measure the movement of the anterior tibial plateau relative to a fixed point on the femoral intercondylar notch and a fixed point on the tibial shaft. Limitations of the study included the fact that they only viewed images in the sagittal plane so rotation of the knee was not evaluated.9

ACL fluoroscopy.jpg
ACL fluoroscopy.jpg


The success of both prophylactic braces for those who have not sustained a knee injury and functional braces is lacking support by evidence. Athletes are often nervous to wear prophylactic knee braces for fear of the effect on their athleticism.10Knee braces can slow sprint speeds, they are heavy so they can increase fatigue, and can lead to other physiological disadvantages such as increased oxygen consumption and increased heart rate.11


FOOTWEAR AND PLAYING SURFACE
Footwear and playing surfaces may have an impact on the risk of ACL injury for a number of reasons. A high level of friction or excessive traction between the shoe and the playing surface can put an athlete at a higher risk for ACL injury. This can be affected by shoe type, playing surface type, and weather conditions.

For example:
  • An increased number of cleats on the sole of shoes results in higher torsional resistance.12
  • In female handball athletes, artificial surface can create a higher torsional resistance compared to hard wood floors.13
  • During rugby, non-contact ACL injuries are more common during periods of low rainfall and high evaporation.14

external image adidas-mundial-team-tf.jpgexternal image adidas-Copa-Mundial-300x199.jpg


INJURY PREVENTION PROGRAMS
We have learned that there are three physiological differences between males and females concerning body biomechanics: neuromuscular control, hormones and anatomy. Of these three, only the neuromuscular difference between males and females can be changed by preventive exercises. Hormones and anatomy are not affected by ACL prevention interventions.15


An ACL injury occurs within 40 milliseconds after initial ground contact. Therefore, intervention programs have been developed to involve neuromuscular retraining with the goal of altering body positioning and movement patterns to avoid known ACL mechanisms of injury. Noyes and Barber-Westin performed a systematic review over 8 neuromuscular retraining intervention programs performed to reduce ACL injury rates in adolescent female athletes. The individual components of each program can be found in Table 1. They found 3 programs significantly reduced non-contact ACL injuries. Out of the 8 programs, the 3 ACL intervention programs that reached significance in injury prevention were Sportsmetric, the Prevent Injury and Enhance Performance program (PEP), and Knee Injury Prevention Program (KIPP) (Table 2). The relative risk reduction ranged from 75% to 100%. However, pooling of data of all ACL intervention programs is not recommended because of numerous methodologic differences among studies.16

Table 1.
ACL Intervention Training Program Components
Program (Year)
Dynamic Warm-up
Plyometrics
Balance
Strengthening
Agility Drills
Flexibility
Sportsmetrics (2012)
10 exercises
Weeks 1-2: 7 jumps
Weeks 3-4: 9 jumps
Weeks 5-6: 7 jumps
None
Based on equipment available: targets core, lower extremity, upper extremity
Sport specific, 30 min in duration
11 exercises
PEP (2005)
3 jogging, running drills
5 jumps
None
3 exercises: quadriceps, hamstring, gastroc-soleus
3 drills
5 exercises
KIPP (2011)
17 exercises
Week 1: 8 jumps
Week 2: 9 jumps
Week 3: 9 jumps
Week 4 and onward: 8 jumps
None
10 exercises: core, lower extremity, upper extremity
3 drills
None
Olsen (2005)
8 jogging, running drills
None
5 exercises on balance mat
2 exercises: quadriceps, hamstring
2 drills
None
KLIP (2006)
None
Weeks 1-2: 4 jumps
Weeks 3-4: 6 jumps
Weeks 5-6: 6 jumps
Week 7 to end: 6 jumps
None
None
4 drills
None
The “11” (2008)
1 jogging exercise
5 jumps
4 exercises, 3 performed on balance mat
4 exercises: 2 core stability, 2 hamstring
None
None
HarmoKnee (2010)
5 exercises
4 jumps
None
6 exercises: 3 core stability, 3 lower extremity
None
6 “muscle activation” exercises
Walden (2012)
None
1 jump for each of 4 levels (1 per session)
None
5 exercises: core, lower extremity
None
None

Table 2.
Intervention Training Programs That Significantly Reduced Noncontact ACL Injury Rates

Trained Athletes
Control Athletes
P Value
Relative Risk Reduction (95% CI)
Number Needed to Treat (95% CI)
Program (Year)
No. of Athletes
No. of NC ACL
No. of AE
NC ACL Injury Incidence Rate
No. of Athletes
No. of NC ACL
No. of AE
NC ACL Injury Incidence Rate
Sportsmetrics (1999 + 2012)
700
1
36,724
0.03
1,120
13
61,244
0.21
0.03
88 (6 to 98)
98 (59 to 302)
PEP (2005)
1,885
6
67,860
0.09
3,818
67
137,448
0.49
<0.0001
82 (58 to 92)
70 (52 to 105)
KIPP (2011)
485
2
20,345
0.1
370
6
12,467
0.48
0.04
75 (-25 to 95)
83 (-503 to 38)

SportsMetric Training Video
https://www.youtube.com/watch?v=RqEn4KNDgUc

Many other studies have found neuromuscular training to be beneficial in the prevention of ACL injury.
  • Mandelbaum et al performed a 2 year study on 2,946 female college soccer players. During the first year of interventions there was an 88% decrease in ACL injury compared to the control group and the second year there was a 74% reduction in ACL injuries compared to the control group. Interventions included educational videos and the PEP.17
  • According to Julie Gilcrest et al, those who participated in the intervention program (on field warm up program stressing proper biomechanics, especially at the knee) showed that the risk of injuring ACL was 1.7 times less (41% decrease) than those who did not participate in an intervention program. Non-contact motor mechanisms were 3.3 times less likely to injure the ACL when compared to the control (no intervention) group. Those who had a previous ACL injury in the intervention group are less likely to re-injure the ACL when compared to females in the control group with similar backgrounds.18
  • In a study by Pasanen et al, risk of non-contact injuries were 66% lower in the intervention group compared to the control group. The intervention group completed an extensive warm-up including carioca, walking lunges, balance and body control, double and single-leg squats, balance board exercises, forward jumps, and stretches of the hamstring and hip flexors among other exercises while the control group did their own traditional warm-up comprised of elements they chose.19
  • In addition, Christopher Bise mentioned in the Physical Therapist’s Guide to Anterior Cruciate Tear that preventative interventions have been shown to lower ACL injuries by 41% for female soccer players.20


curious cat.pngFYI: According to ‘Motor Learning Strategies’, females reduced knee varus moment with verbal cues better than with visual or no cues. According to the article, males learn better with visual cues compared to women. Adding video instructions or verbal feedback to training may promote long term results and optimize ACL prevention programs in females.21

ACL Prevention Exercises
https://www.youtube.com/watch?v=xWBSf4BfKRk


CONCLUSION
In conclusion, we recommend using pre-participation screening to identify at-risk individuals. To compliment pre-screening, we encourage female athletes to participate in intervention programs that focus on neuromuscular training and biomechanical control to reduce the risk of ACL injury.

In regards to preventative bracing, more research should be done to better understand the effect on our target population. Ultimately, athlete preference should be considered when recommending preventative bracing. Footwear and playing surfaces also require more research to better identify the factors that contribute to ACL injury.


REFERENCES
  1. ACL Injury: Does It Require Surgery? American Academy of Orthopaedic Surgeons Web site. http://orthoinfo.aaos.org/topic.cfm?topic=a00297 Updated September 2009. Accessed April 2014.
  2. Hewett TE, Myer GD, Ford KR, et al. Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study. Am J Sport Med. 2005; 33(4): 492-501.
  3. Cates W, Cavanaugh J. Advances in rehabilitation and performance testing. Clin Sports Med. 2008; 28(1):63-76.
  4. Myer GD, Ford KR, Hewett TE. Rationale and techniques for anterior cruciate ligament injury prevention among female athletes. J Athl Train. 2004; 39(4): 352-364.
  5. Redler LH, Watling JP, Dennis ER, Swart E, Ahmad CS. Reliability of field-based drop vertical jump screening test for ACL risk assessment. Phys Sportsmed. 2016; 44(1): 46-52.
  6. Zeller BL, McCrory JL, Kibler WB, Uhl TL. Differences in kinematics and electromyographic between men and women during single-legged squat. Am J Sports Med. 2003; 31(3):449-56.
  7. Boden BP, Breit I, Sheehan FT. Tibiofemoral alignment: contributing factors to noncontact anterior cruciate ligament injury. J Bone Joint Surg Am. 2009; 91(10): 2381-2389.
  8. Mokhtarzadeh H, Ng A, Yeow C, Oetomo D, Malekipour F, Lee P. Restrained tibial rotation may prevent ACL injury during landing at different flexion angles. The Knee. 2015; 22: 24-9.
  9. Jalali M, Farahmand F, Mousavi S, et al. Fluoroscopic analysis of tibial translation in anterior cruciate ligament injured knees with and without bracing during forward lunge. Iran J Radiol. 2015; 12(3): e17832.
  10. Rishiraj N, Taunton JE, Lloyd-Smith R, Woollard R, Regan W, Clement DB. The potential role of prophylactic/functional knee bracing in preventing knee ligament injury. Sports Med. 2009; 39(11): 937-60.
  11. Najibi S, Albright J. The use of knee brace, part 1: prophylactic knee braces in contact sports. Am J Sports Med. 2005; 33(4): 602-11.
  12. Lambson RB, Barnhill BS, Higgins RW. Football cleat design and its effect on anterior cruciate ligament injuries: A three-year prospective study. Am J Sport Med. 1996; 24(2): 155-159.
  13. Renstrom P, Ljungqvist A, Arendt E, et al. Non-contact ACL injuries in female athletes: an International Olympic Committee current concepts statement. Br J Sports Med 2008;42:394-412.
  14. Orchard J, Seward H. Epidemiology of injuries in the Australian Football League, seasons 1997-2000. Br J Sports Med 2002;36:39-44
  15. Yoo JH, Lim BO, Ha M, et al. A meta-analysis of the effect of neuromuscular training on the prevention of anterior cruciate ligament injury in female athletes. Knee Surgery. 2010; 8(6): 824-830.
  16. Noyes F, Barber-Westin S. Neuromuscular retraining intervention programs: do they reduce noncontact anterior cruciate ligament injury rates in adolescent female athletes? Arthroscopy. 2014;30(2):245-255
  17. Mandelbaum BR, Silvers HJ, Watanabe DS, Knarr JF, Thomas SD, Griffin LY, et al. Effectiveness of a neuromuscular and proprioceptive training program in preventing anterior cruciate ligament injuries in female athletes: 2-year follow-up. Am J Sports Med. 2005;33(7):1003–10
  18. Gilchrist J, Mandelbaum BR, Melancon H, Ryan GW, Silvers HJ, Griffin LY, et al. A randomized controlled trial to prevent noncontact anterior cruciate ligament injury in female collegiate soccer players.Am J Sports Med. 2008;36(8):1476–83.
  19. Pasanen K, Parkkari J, Pasanen M, Hiilloskorpi H, Makinen T, Jarvinen M, et al. Neuromuscular training and the risk of leg injuries in female floorball players: cluster randomised controlled study. BMJ. 2008;337:a295.
  20. Bise, C. (2011) Anterior Cruciate ligament (ACL) tear. Available at: http://www.moveforwardpt.com/symptomsconditionsdetail.aspx?cid=d8e73ca8-71f4-48a7-92f8-675bca38232c (Accessed: 13 April 2016)
  21. Benjaminse A, Otten B, Gokeler A, Diercks RL, Lemmink KA. Motor learning strategies in basketball players and its implications for ACL injury prevention: a randomized control trial. Knee Surg Sports Traumatol Athrosc. 2015; 1-12.