ACL injury screening and prevention CATS meeting 2016

1. Aaron Gray, MD
@MizzouSportsDoc
University of Missouri

2. I have received a Mizzou Advantage grant for research of
ACL injury risk screening with video game technology.
I have no other financial disclosures relevant to this talk.
Matthew Busch, Missourian

3. • Epidemiology of ACL Tears in
Athletes
• Factors for the Female ACL Tear
“Epidemic”
• Neuromuscular Deficits in Female
Athletes
• Screening Tests for ACL Injury
Risk
• ACL Injury Prevention Programs

4. • About half of ACL injuries were in competitions and the
injury rate was higher for competitions compared to
practices.

5. • One athlete participant in one practice or game equals
one athletic exposure
• Example: 25 athletes completing one practice is 25
athletic exposures

6. 0
0.5
1
1.5
2
2.5
3
Female Male
4.1x
2.8x
Stanley et al. AJSM, 2016.

7. www.daytondailynews.com

8. • Female athletes have 4-6x increased risk of ACL
injuries than males in similar cutting sports
• Since Title IX was passed in 1972
• 10x increase in participation in girls HS athletics
• 5x increase in female participation in collegiate sports
Arendt, et al. J Athl Train, 1999.
NCAA (2002) and NFHS (2009) published data

9. • Estimated cost of surgery and rehab for an ACL injury is
$17,000-25,000
• Estimated 200,000 ACL reconstructions annually in US at
estimated cost of over $2 billion
• In 2001 estimated 38,000 ACL injuries in girls and
women at cost of approximately 650 million annually
Brukner & Khan. Clinical Sports Medicine, 4th ed. 201
Toth & Cordasco. J Gend Specif Med 2001.

10. Soccer was highest mechanism of injury (26.6%) in Kaiser
Permanente ACL registry
ACL tears peak at age 16 in female athletes
Maletis, et al. J Bone Joint Surg Am 2011.
Female athletes who play
soccer or basketball year-
round have an annual ACL
tear rate of 5%
Prodromos, et al. Arthroscopy 2007.

11. • Intrinsic variables with gender differences
• Anatomic
• Hormonal
• Neuromuscular

12. • Proposed gender differences include
• Smaller size and different shape of intercondylar notch
• Smaller ACL within smaller notch
• Wider pelvis and greater Q angle
• Greater ligament laxity
• Since little can be done to modify these
anatomical findings, focus has moved to what
can be changed

13. • Hormonal effects on
the musculoskeletal
system is a complex
process
• Most studies
suggest increased
risk of ACL injury in
preovulatory phase
of menstrual cycle

14. • No evidence that oral contraceptives
decrease ACL injuries

15. • 4-6 inch growth spurt
around 10-11 years
old
• Center of mass rises
through puberty
• After growth spurt
female adolescents do
not gain
“neuromuscular spurt”
that males achieve
Huston & Wojtys. AJSM 1996.

16. Ford et al. Med Sci Sports Ex 2010.

17. • 60-80% of ACL injuries are non-contact
• Two common mechanisms
Landing Cutting
Krosshaug et al. AJSM 2007.

18. • Dynamic knee valgus on landing
• Knee is relatively straight on landing
• Most or all of weight is on one leg
• Trunk is tilted laterally (center of mass is outside feet)

19. Olsen et al. AJSM 2004.

20. S

25. E

26. S

31. E

32. • Ligament Dominance
• Quadriceps Dominance
• Leg Dominance
• Trunk Dominance (Core Dysfunction)
Hewett et al. NAJSPT, 2010

33. • Muscles do not sufficiently absorb ground
reaction forces
• Joint and ligaments must absorb high forces
over a short period of time
• Posterior kinetic chain (gluteals, hamstrings,
gastrocnemius, soleus) must be recruited to
avoid ligament dominance

34. • GRF are directed
toward the center of
mass in the trunk of
the athlete
• Lateral trunk
movement forces
lower leg into dynamic
valgus

35. • Decreased
hamstring strength
and recruitment
• Females activate
quadriceps more
than males for initial
knee stabilization

36. • Females land with less knee flexion than males
• 3x less posterior kinetic chain activation during landing
than size matched males
Hewett et al. AJSM 1996.
• Attempt to stabilize joint with quadriceps which
results in anterior tibial translation
• Quadriceps contraction increases ACL strain between
10° and 30° of knee flexion

37. Quadriceps
• Single insertion
• Patellar tendon into tibial
tubercle
• Less flexion on landing
• Anterior tibial translation
increases ACL stress
Posterior Chain
Muscles
• Multiple, varied insertions
• Medial and lateral tendons
give frontal plane control
• More flexion on landing
• Prevents anterior tibial
translation which
decreases ACL stress

38. • Females tend to be more one-leg dominant than
males
• During an ACL injury most (or all) weight is on
one leg
• Athletes with increased asymmetry have greater
risk of injury
Hewett, et al. AJSM 2005.
KOMU.com

39. • Athletes who had deficits of active core
proprioceptive had greater risk of ACL injury
Zazulak, Hewett, et al. AJSM 2007

41. Three steps needed to validate a screening test to predict
and prevent sports injuries
1. Prospective cohort study to identify risk factor(s) and
define cut-off value(s)
2. Validate test and cut-off value in multiple cohorts
3. Randomized controlled trial to test effect of combined
screening and intervention program
Bahr R. BJSM Published Online First, April 25, 20

42. AJSM, 2005.

43. 205 female HS athletes in
soccer, basketball and
volleyball prospectively
measured for
neuromuscular control with
3D motion analysis
Hewett et al. AJSM 2005

44. 8.4˚ more dynamic valgus 7.6˚ more dynamic valgus 10.5˚ less knee flexion

45. External Knee Abduction Moment Knee Abduction Angle at Initial Contact

46. Norwegian professional female handball and soccer athletes completed a DVJ in
preseason

47. Take Home: Medial knee displacement during the DVJ was
only statistically significant predictor of ACL injury risk in
Norweigian professional female handball & soccer players with
Older population than Hewitt’s 2005 study and likely already
participating in injury prevention program

48. • Similar to Hewitt’s Drop Vertical Jump protocol
except:
• 2 video cameras are used (frontal and side view)
instead of marker based motion capture
• Participants jump to a distance 50% of their height and
immediately perform a maximum vertical jump
Padua, et al. AJSM 2009.

49. Padua, et al. AJSM 2009.

50. Padua, et al. AJSM 2009.

51. Padua, et al. AJSM 2009.

52. 2691 subjects who were incoming freshman at 3 large US
military academies
Simultaneously analyzed with sophisticated laboratory
system and inexpensive field analysis system (LESS)
Results: Valid and reliable tool for identification of subjects
with landing errors in multiple planes
Padua, et al. AJSM 2009.

53. • Padua et al. J Athletic Training 2015.
• 829 elite-youth soccer athletes (348 boys, 481 girls)
• Age= 13.9 ± 1.8 years, age range = 11 to 18 years
• Followed for 1217 athlete-seasons
• 7 non-contact ACL tears occurred
• Uninjured participants had lower LESS
scores (4.43 ± 1.71) than injured participants
(6.24 ± 1.75; P = .005)

54. • James et al. Sports Health, 2015.
• 34 Division 1 male and soccer athletes performed a drop-
landing task and were scored with LESS and lower
extremity injuries were tracked during season
• No statistically differences found in LESS
scores in those with & without injury history.
• Those injured during year had similar LESS
scores to those uninjured.

55. Anterior Reach of the mSEBT
Willis, et al. Under Review

56. Posteromedial Reach of the mSEBT
Willis, et al. Under Review

57. Posterolateral Reach of the mSEBT
Willis, et al. Under Review

58. • 4 cm or more difference in anterior reach distance
between limbs at 2.5 higher risk of suffering lower leg
injuries in high school basketball players
• Females who demonstrated less than 94% composite
reach distance were 6.5 times more likely to sustain a
lower extremity injury.
Plisky, J Orthop Sports Phys Ther. 2006.

62. • 3D lower extremity angles difficult to calculate without
accurate hip measurement
• Knee to Ankle Separation Ratio (KASR) is a reliable
surrogate for dynamic knee valgus measurements
Steffen, et al. IOC World Conference on
Prevention of Injury & Illness in Sport, Monaco
2014.
Mizner, et al. CJSM,
2012.

63. Distance between knees/Distance between ankles

64. • Hypothesis: Screening will be safe, efficient, and will
identify known gender disparities
• Population: 180 healthy high school athletes
• Ages 14-18 (Mean age: 16.9 ± 1.31)
• 80 males, 100 females
• BMI: 22.8 ± 3.7

65. • Safety
• There were no injuries reported during the screening testing
• Efficiency
• Using two motion sensor device stations, it took 3 minutes to
screen and test each subject per station

66. Average KASR at Initial
Contact
Males: 1.13
Females: 0.967
KASR <0.9
Females 34%
Males 3%

67. Average KASR at Peak
Flexion
Males: 1.26
Females: 1.01
KASR <0.9
Females 28%
Males 3%

68. www.ukathletics.com

70. Hewett et al. NAJSPT 2010

71. Focuses on increasing
recruitment of posterior
kinetic chain
• Gluteus maximus
• Biggest, strongest
muscle in body
• Only three plane
controller of femoral
position
• Quad activation reduces
contraction of gluteus
maximus and hamstrings

72. Squat jumps with hips and knees at 90/90
Hewett et al. NAJSPT 2010

73. Russian (or Nordic) Hamstring Curls
Hewett et al. NAJSPT 2010

74. Swiss Ball Hamstring Curl
Combination posterior chain and core
Hewett et al. NAJSPT 2010

75. Single leg balance
and hopping help
restore side to side
symmetry
Hewett et al. NAJSPT 201
Perturbations on
upside down Bosu
ball

76. Core stability training
Hewett et al. NAJSPT 2010.
Transversus
abdominis, multifidis,
pelvic/hip stabilizers

77. Stabilization of pelvis through hip abductors
and rotators is key!
Poor hip external rotation strength after ACL
reconstruction had 8X greater chance of another
ACL tear
Paterno et al. AJSM 2010

78. AJSM 2006
Analyzed 6 studies looking at effectiveness of neuromuscular
training interventions in reducing ACL injuries
Hewett, et al. AJSM 2006

79. Hewett, et al. AJSM 2006
29 total ACL injuries in training group vs 110 in control group
3 of 6 interventions showed significant reduction in ACL injury
rates, while 5/6 demonstrated positive trends and reduction of
odds ratio

81. • Prospective cohort study high school aged female
soccer, basketball, and volleyball players
• Intervention group - 15 female teams (n=366)
• Control group – 15 female teams (n=463)
• Control group – 13 male teams (n=434)
• Intervention – 6 week neuromuscular training 3x/wk for
60-90 min/session before season
• Results – Significantly decreased noncontact ACL
injuries by 72% (p<0.5)

82. • Prospective cohort study for 3 seasons in Norwegian
female handball
• Intervention started 2nd (n=855) and 3rd (n=850) seasons
• Exercises – balance board, jump exercises, balance
mat exercises
• Results –
• 29 ACL injuries initial season, followed by 23 (p=.62)
2nd year and 17 (p=0.15) 3rd year
• Non-contact ACL injuries decreased from 18 to 7
(p=0.04) from 1st to 2nd year
• ACL risk decreased 36%

83. • Plyometric training
• Trains muscles, connective tissue, and nervous system
to effectively carry out stretch shortening cycle and
appears to reduce ACL injuries
• Technique education and feedback
• Encouraging soft landing and maintaining knee over
toe position
• Balance, core stability, postural control training
• Strengthening exercises

84. • Neuromuscular training programs can be
effective at improving performance measures of
speed, strength, and power
• The key for compliance!

85. • 61 NCAA Div 1 teams were randomized
• Noncontact ACL injury rate was 3.3x less in
intervention group (p=0.66, 70% decrease)
• Intervention athletes with history of ACL
reconstruction were significantly less likely to
suffer another ACL injury (p=0.046)
AJSM 2008

87. • FIFA is the international soccer governing body
• F-MARC is their medical research committee
whose focus is injury prevention and
improving standards of care for football
players worldwide
• Developed the 11+ warm up program to
decrease injuries

92. • Grooms, et al. J. Athl Training 2013.
Male college soccer athletes showed reduction
in relative risk of lower extremity injury of 72%
No studies looking at FIFA 11+ specifically
recorded ACL injuries

93. • ACL screening tests for injury risk are promising but
nothing works really well yet.
• ACL injury prevention programs work for female athletes!

94. • Measure injury rates and compare to NCAA published
data
• Only way to see if injury prevention programs work!
• Coordinate ACL injury prevention programs with strength
and conditioning colleagues

95. • @MizzouSportsDoc
• grayad@missouri.edu