Orthopedic Grand Rounds at Univ. of Missouri by Aaron Gray, MD, Sports Medicine Specialist. Discusses Epidemiology, risk factors, and focuses on prevention of ACL injuries in female youth athletes.
2. I have no financial disclosures
Matthew Busch, Missourian
3. • Numbers Behind the “Epidemic”
• Neuromuscular Deficits in Young
Female Athletes
• Knee Injury Prevention
Programs
• Ongoing Research
4. • Female athletes have 4-6x increased risk of ACL
injuries than males in similar cutting sports
Arendt, et al. J Athl Train, 1999.
• Since Title IX was passed in 1972
• 10x increase in participation in girls HS athletics
• 5x increase in female participation in collegiate sports
NCAA (2002) and NFHS (2009) published data
5. • 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
Brukner & Khan. Clinical Sports Medicine, 4th ed. 201
• In 2001 estimated 38,000 ACL injuries in girls and
women at cost of approximately 650 million annually
Toth & Cordasco. J Gend Specif Med 2001.
6. • Soccer was highest mechanism of injury (26.6%) in
Kaiser Permanente ACL registry
Maletis, et al. J Bone Joint Surg Am 2011.
• Year-round female athletes who play soccer or basketball
have ACL tear rate of 5%
Prodromos, et al. Arthroscopy 2007.
ACL tears peak at age 16 in
female athletes
8. • 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
9. • Hormonal effects on
the musculoskeletal
system is a complex
process
• Most studies
suggest increased
risk of ACL injury in
preovulatory phase
of menstrual cycle
10. • No evidence that oral contraceptives
decrease ACL injuries
11. • 4-6 inch growth spurt
around 10-11 years
old
• After growth spurt
female adolescents do
not gain Huston & Wojtys. AJSM 1996.
“neuromuscular spurt”
that males achieve
• Center of mass rises
through puberty
12. • 60-80% of ACL injuries are non-contact
• Two common mechanisms
Landing Cutting
Krosshaug et al. AJSM 2007.
13. • 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)
29. • Cincinnati Children’s and Ohio State researchers have
used a coupled biomechanical-epidemiological approach
Tim Hewett, PhD Greg Myer, PhD Kevin Ford, PhD
30.
31. 205 female HS athletes in
soccer, basketball and
volleyball prospectively
measured for
neuromuscular control with
3D motion analysis
Hewett et al. AJSM 2005
35. • Ligament Dominance
• Quadriceps Dominance
• Leg Dominance
• Trunk Dominance (Core Dysfunction)
Hewett et al. NAJSPT 2010
36. • 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
37. • GRF are directed toward
the center of mass in the
trunk of the athlete
• Lateral trunk movement
forces lower leg into
dynamic valgus
• Straw Analogy
38. • Decreased hamstring
strength and
recruitment
• Females activate
quadriceps more than
males for initial knee
stabilization
39. • 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
40. Posterior Chain
Quadriceps Muscles
• Single insertion • Multiple, varied insertions
• Patellar tendon into tibial • Medial and lateral tendons
tubercle give frontal plane control
• Less flexion on landing • More flexion on landing
• Anterior tibial translation • Prevents anterior tibial
increases ACL stress translation which
decreases ACL stress
41. • 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 greater2005.
Hewett, et al. AJSM
risk of injury
KOMU.com
42. • Athletes who had deficits of active core
proprioceptive had greater risk of ACL injury
Zazulak, Hewett, et al. AJSM 2007
46. 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
47. Squat jumps with hips and knees at 90/90
Hewett et al. NAJSPT 2010
50. Swiss Ball Hamstring Curl
Combination posterior chain and core
Hewett et al. NAJSPT 2010
51. Single leg balance Perturbations on
and hopping help upside down Bosu
restore side to side ball
symmetry
Hewett et al. NAJSPT 201
52. Core stability training
Transversus
abdominis, multifidis,
pelvic/hip stabilizers
Hewett et al. NAJSPT 2010.
53. 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
54. • Balance training
• Landing with flexion at knee and hip
• Controlling body motions when decelerating and
pivoting
• Core stability strengthening
• Feedback on technique of drills
55. AJSM 2006
Analyzed 6 studies looking at effectiveness of neuromuscular
training interventions in reducing ACL injuries
56. 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
57.
58.
59. • 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 – Significiantly (p<0.5) noncontact ACL injuries
by 72%
60. • 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%
61. • Soccer players age 14-18 enrolled in cohort
study
• Intervention group (n=1885), controls (n=3818)
• Results – Significant decrease in ACL injury rate
in intervention group(0.09/1000 athlete
exposures) compared to control (0.49/1000 AE)
• Limitations – end of season reporting,
mechanism of injury may have potential
inaccuracies
62. • 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
63. • Neuromuscular training programs can be
effective at improving performance measures of
speed, strength, and power
• The key for compliance!
64. • 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
68. • 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
69.
70. • Steffen et al. Scand J Med Sci Sports 2008
• “FIFA 11” exercises for core stability, lower extremity
strength, neuromuscular control and agility
• No difference in injuries between groups
• Very poor compliance
71. • Soligard et al. BMJ 2008.
• Comprehensive warm-up program to prevent injuries in
young female footballers: cluster randomized controlled
trial
• Population – 1892 female soccer players ages
13-17 in Norway
• Intervention changed to “11+” which was to be
used as an active warm up for practice and
games
• Added progressive difficulty with exercises
72. • Results –
• Improved compliance from previous
study
• Significantly lower risk of overall
injuries (32%), overuse injuries
(53%), severe injuries (45%)
• Reduction of risk of knee injuries
(38%) and acute injuries (26%)
• Did not specifically record ACL
injuries
78. • Retrospective Survey of High School Soccer Coaches in
Missouri on estimated athlete exposures (EAE) and ACL
injuries
• Girl’s: 0.167 ACL tears/1000 EAE
• 12 Tears in ~72,000 EAE
• Boy’s: 0.08 ACL tears/1000 EAE
• 6 Tears in ~74,100 EAE
• Limitations
79. • Girl’s: 0.167 ACL tears/1000 estimated exposures
• Boy’s: 0.08 ACL tears/1000 estimated exposures
• 72,000 female exposures makes 2nd largest high school
female ACL injury rate study in literature to our
knowledge
82. • Prospective study of ACL prevention
programs on high school female athletes in
Missouri
• Prospective study of knee abduction angle
(dynamic valgus) during landing tasks in
high school athletes as predictor of ACL
injuries
Hinweis der Redaktion
ACL tear risk may be up to 9x male counterparts
D, the ACL injury is believed to have occurred at the time the foot is planted to push offwith the right knee. The foot is firmly fixed to the floor (externally rotated), and she has a wide stance. The knee is in slight flexion(15°), internal rotation of the tibia (10°) and valgus (20°). Approximately 80% of her body weight is on the injured leg. E, themoment just after the injury, with an increasing valgus angle. F, the injured knee collapses, and she continues to fall to the floor.
The sequence of events leading to a left-sided ACL injury to a back player (in red). A, taking off on her left leg for ajump shot from the right-back position. She has taken 2 steps with the ball and is moving at high speed. B, the injured player ispushed slightly off-balance disturbed by the opponent before the landing. C, off balance in the air, preparing to land with herbody weight on the left leg. D, the ACL in her left knee is believed to have been injured immediately after foot strike. The foot isfirmly fixed to the floor and externally rotated. The knee is in slight flexion (20°), external rotation of the tibia (10°) and valgus(10°). E, the moment just after the injury, with increasing knee valgus and flexion. F, the injured knee collapses, and she continuesto fall to the floor.
D, the ACL injury is believed to have occurred at the time the foot is planted to push offwith the right knee. The foot is firmly fixed to the floor (externally rotated), and she has a wide stance. The knee is in slight flexion(15°), internal rotation of the tibia (10°) and valgus (20°). Approximately 80% of her body weight is on the injured leg. E, themoment just after the injury, with an increasing valgus angle. F, the injured knee collapses, and she continues to fall to the floor.
AOSSM award for outstanding clinical or laboratory based research efforts that are applicable to the understanding, care or prevention of injuries in sports
8.4 degrees more dynamic valgus on initial contact7.6 degrees more dynamic valgus at peak flexion10.5 degrees less knee flexion at peak flexion
8.4 degrees more dynamic valgus on initial contact7.6 degrees more dynamic valgus at peak flexion10.5 degrees less knee flexion at peak flexion
Ensemble average plot of knee abduction angle (T1 SD, gray-shaded area) throughout the stance phase of the DVJ. The stance phasebegins with initial ground contact (0% stance) and ends with toe-off (100% stance).
Newton’s third law of equal and opposite reaction forces is always obeyed when an athlete lands or cuts. The surface his the athlete back with an equal and opposite force.
Significant differences in uninjured and injured females with regard to knee injuries and ligament/meniscal injuries. There were a low number of ACL tears which decreased ability to find statistical significance in ACL tears.*** Uninjured females actually had better core propreoception than uninjured malesPrevention programs for females should include dynamic trunk training while in males not as necessary
Gluteus maximusBiggest, strongest muscle in bodyonly three plane controller of femoral position. Quad activation reduces contraction of gluteus maximusand hamstrings
Eccentric and Concentric
Make it harder by doing the same with single leg
Also works on posterior chain
Less Rectus abdominus
Also works on posterior chain
8.4 degrees more dynamic valgus on initial contact7.6 degrees more dynamic valgus at peak flexion10.5 degrees less knee flexion at peak flexion
