ACL Prevention
Amanda KW Kelly, MD
Case Western Reserve University
Rainbow Babies and Children’s Hospital
Outline
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Background
Injury risk factors
ACL prevention programs
Background
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250,000 ACL injuries/yr in USA

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80 - 90% return to previous level of play
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$1.5 billion annual cost
Typical recovery 6-9 mo
> 70% ACL injuries are NON-contact
Boden 2000 Physspportsmed
Importance of ACL Injury
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Season ending injury
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6-9 mo recovery time
Children often must wait several yrs for repair
Costly
ACL Anatomy
PCL
LCL
ACL
MCL
ACL: Function

Keep tibia from sliding forward on the femur
Injury Mechanisms
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Pivot
Landing from
jump
Contact
http://sportzfun.com/v-web/gallery/slideshow.php?set_albumName=soccer
Injury Mechanism: Pivot

Deceleration + change of direction, foot planted
Causes twisting injury of knee
 Traction at shoe/playing surface interface
 Often close to another player

ACL
Mechanism: Pivot

Importance of
ground-shoe surface
interface in pivot
mechanism
Shoe surface interface
Mechanism: landing
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Knee slightly flexed on landing
Quad pulls tibia forward
Mechanism: Contact
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Hit on outside of leg
Foot planted
Twisting of knee
Mechanism
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Pivoting with knee slightly bent, twisting
knee
Landing from jump: knees slightly bent,
quads pull tibia forward
Too much shoe traction
Poor balance
Uneven ground throwing off balance
Risk Factors
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Poor landing + pivot style
Stronger quads than hamstrings
Shoe / playing surface interface
Playing surface quality
Female gender
Risk Factors
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Landing / Pivoting with knee slightly bent
Places ACL in vulnerable position
 Additional torsion/twisting can  injury

Boden 2000 Physsportsmed
Risk Factors
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Hamstring/Quadriceps imbalance
Poor hamstring strength
Hamstrings protect ACL
 Quads stretch/stress ACL
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Slow activation of hamstring
muscles with pivot / landing
Hewett AJSM 1999, Crosier AJSM 2002, Huston 1996
AJSM, Orchard AJSM 1997, Baratta AJSM 1988
http://www.preventaclinjury.com/knee_biomechanics.htm
Risk Factors
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Footwear
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Longer cleats at edge of sole with fewer,
smaller cleats in the middle of the sole
 ’s
torsional resistance
Lambson 1996 AJSM
Risk Factor

Uneven playing surface
Unexpected foot position may change
muscle activation patterns
 Balance thrown off

Boden, Orthopedics
Risk Factors
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Female Gender
2-8x more common in girls
 Poor ham:quad strength
 Activate hams more slowly
 Land with knees sl bent
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 Boys
land with knees more bent
Female Gender
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Hormonal Influences
ACL has estrogen receptors
 Estrogen can  ligament looseness
 Estrogen levels  in girls compared to boys
 Estrogen ’d at specific times in menstrual cycle
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 Studies
VERY inconsistent
 Every phase of cycle has been implicated in at
least 1 study
Female Gender
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Knee anatomy
Smaller intercondylar
notch
 ACL may get stretched
across bone and torn
 Athletes with bilateral
ACL injuries have smaller
ICN

Harner 1994 AJSM, Anderson 1999 AOSSM
www.hughston.com
Female Gender
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Lower extremity alignment
Women more knock-kneed
 May allow quad to exert more
stress on ACL
 Data not great

Nisell 1985 ActaOrthopScandSuppl
www.hughston.com
Prevention Strategies
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Shoe wear / field surface
Bracing
Exercise Programs
Change muscle strength + activation
 Change landing / Pivoting patterns
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 Sportmetrics
 PEP
Prevention: shoe wear
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Shoes with lower ACL injury risk:
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Cleats flat, all the same size on forefoot
Screw in cleats with 0.5in ht/diameter cleats
Pivot disk: 10-cm circular edge on sole of forefoot
Flat shoes on turf
Want balance of too much / too little traction
Lambson 1996 AJSM
Prevention
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Improve playing field????
Bracing
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Several studies
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Inconclusive results
 No
change in muscle activation
patterns
 No  ACL shown in any study
Loads placed on brace during
play exceeds brace
 BUT, many kids who have had
ACL surgery FEEL more stable
in brace
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Training Programs
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Balance board training
Improves balance + joint position sense
 Caraffa, 1996, Knee Surg Sports Traum Arthrosc
 20 min training sessions
 87%  ACL injuries

 7x
 injury
Training Programs
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Frappier Acceleration Training Program
Frappier Acceleraton, Fargo, North Dakota
 Heidt, 2000, Amer Orthop Soc Sports Med
 7 wk preseason training: 3d/wk
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 2d/wk
treadmill sessions
 1d/wk plyometric (jump training)
’d total # serious knee injuries
 ACL ’d but not significantly
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Training Programs
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Sportmetrics
Hewett, 1999, Amer J Sports Med
 Cinicinnati Sportsmedicine Research and
Education Foundation
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PEP (Prevent injury Enhance Performance)
Mandelbaum, 2005, Amer J Sports Med
 Santa Monica Orthopedic and Sports Medicine
Research Foundation
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Program Goals
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Emphasize proper jump/land
techniques
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Land on balls of feet
 Soft
landing
 Toe-to-heel rocking of the foot
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 ground reactive forces
Knees flexed
 Knees forward
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 Discourage
inward buckling of knees
(knock-kneed landing)
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Chest over knees
Hewett 1999 AJSM, Mandelbaum 2005 AJSM, Boden
2000 Physportsmed
www.physsportsmed.com
Training Programs
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Sportmetrics
6 week Preseason-training program
 60 – 90 minute work-out
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PEP
15 minute work-out
 Use in place of usual pre-practice warm-up 3 d/wk
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PEP Program
Designed
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Warm-up
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to replace usual warm-up
Jog 50yd
Shuttle run 50yd
Backward run 50yd
Stretch
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Calf, quad, ham, inner
thigh, hip flexor
2 x 30s each
correct
Mandelbaum 2005 AJSM
incorrect
PEP Program
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Strength
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Walking lunges 20yd x 2
Russian hamstr 30s
Single toe raise 30x
Mandelbaum 2005 AJSM
PEP Program
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Plyometrics
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Lateral hops 30s
Forward hops 30s
Single leg hops 30s
Vertical jumps 30s
Scissor jumps 30s
Mandelbaum 2005 AJSM
PEP Program
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Agilities
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Shuttle run 40yd
Diagonal run 40yd
Bounding run 50yd
Knees bent
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Avoid upright
position
correct
Mandelbaum 2005 AJSM
incorrect
Sportsmetrics
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Warm-up:
Stretching: 3 sets, 30s each
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Calf, quad, hamstring, hip flexor, IT Band, low
back, posterior deltoids, latissimus,
pects/biceps
Skipping: 2 laps
Side shuffle: 2 laps
Sportsmetrics
Phase I: Technique
Week 1 Week 2
Wall jumps
Tuck jumps
Broad jumps: hold landing
Squat jumps
Double-leg cone jumps (Side-side/front-back)
180 jumps
Bounding in place
20s
20s
5 reps
10s
30s/30s
20s
20s
Hewett 1999 AJSM
25s
25s
10 reps
15 s
30s/30s
25s
25s
Sportsmetrics
Phase II
Week 3
Week 4
Wall jumps
Tuck jumps
Jump, jump, jump, vertical jump
Squat jumps
Bounding for distance
Double-leg cone jumps
Scissors jump
Hop, hop hold landing
30s
30s
5 reps
20s
1 run
30s/30s
30s
5 rep/leg
30s
30s
8 reps
20s
2 runs
30s/30s
30s
4 rep/leg
Hewett 1999 AJSM
Sportsmetrics
Phase III
Week 5
Week 6
Wall jumps
Step, jump up, down, vertical
Mattress jumps (Side-side/front-back)
Single-leg jumps distance
Squat jumps
Jump into bounding
Hop, hop, hold landing
30s
5 reps
30s/30s
5 reps/leg
25s
3 runs
5 reps/leg
30s
10 reps
30s/30s
5 reps/leg
25s
4 runs
5 reps/leg
Hewett 1999 AJSM
Jump Definitions
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180 jumps: 2-footed, rotate 180  in the air
Bound for distance: start bounding in place, increase
distance with each step, knees high
Broad jumps-hold landing: 2-footed jump, as far as
possible hold landing 5s
Cone jumps: double leg, side-side, front-back
Hop, hop, stick: single leg hop, stick landing 5s
Jump into bounding: 2-footed jump, land on 1 leg,
progress into bounding for distance
Jump, jump, jump, vertical: 3 broad jumps with
vertical jump after last broad jump
Mattress jumps: 2-footed jump on mattress/tramp,
side-side + front-back
Hewett 1999 AJSM
Jump Definitions
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Scissors jump: start in stride position, one foot in front
of other, jump up alternating foot position in air
Single-leg jumps, distance: single-leg hop for distance,
hold landing 5s
Squat jumps: standing jump, raise arms overhead, land
in squat position hands on floor
Step, jump up, down, vertical: 2-footed jump onto step,
jump off with 2 feet, then vertical jump
Tuck jump: standing, bring both knees up to chest,
repeat
Wall jumps: ankle bounces, arms overhead bounce
up/down off of toes
Hewett 1999 AJSM
Sportsmetrics
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Weight-training: 12 reps upper body, 15 lower
Abdominal curl
 Back hyperextension
 Leg press
 Calf raises
 Pullover
 Bench press
 Lat pull downs
 Forearm curl
 Warm-down, stretch
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Hewett 1999 AJSM
http://www.sportsmetrics.net/
Training Programs
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Both PEP and Sportmetrics well studied
Aim:

Change landing / pivoting patterns
 Flex
knees more
 Stop over several steps instead of sudden stop


Improve hamstring strength + activation
BOTH prevent ACL + other serious knee
injury by achieving these aims
Goals
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Emphasize proper landing technique
RIGHT
WRONG
Proper landing
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Before Training
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After training
Barber-Westin, 2006, AJSM; Noyes 2005 AJSM
Decreased Injury
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’d non-contact injuries in trained groups
UT: Untrained
T: Trained
MC: Male
Control
0.5
0.4
0.35
0.3
Injury/
1000
exp
0.5
0.4
0.3
0.2
0.2
0.05
0.1
0
0
0.47
UT
T
MC
Sportsmetrics
Hewett 1999 AJSM
0.09
0.1
0
UT
T
PEP
Mandelbaum 2005 AJSM
Performance Enhancement
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 vertical jump
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 strength
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10%  jump height
44%  hamstring strength
 sprint speed
Improved power endurance
Improved running economy
Diallo JSMPF 2001, Turner JSCR 2003, Siegler JSCR 2003, Spurs EJAP
2003, Newton MSSE 1999. Witzke MSSE 2000, Hewett 1999 AJSM
Improved Bone Density
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Female athletes participating in jump
training build more bone
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 risk for stress fracture
 Prevent
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time lost from injury
 risk for osteoporosis later in life
References
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Barber-Westin SD et al. Jump-Land Characteristics and muscle
strength development in young athletes. Amer J Sports Med.
2006: 34(3)1-10
Boden BP et al. Etiology and prevention of noncontact ACL
injury. PhysSportsMed. 2000: 29(4)
Caraffa A et al. Prevention of anterior cruciate ligament injuries
in soccer: a prospective controlled study of proprioceptive
training. KneeSurgSportsTraumatolArthrosc. 1996:4:19-36
Heidt RS et al. Avoidance of soccer injuries with preseason
conditioning. AmJSportsMed. 2000: 28(5)659-62
Hewett TE et al. The effect of neuromuscular training on the
incidence of knee injury in female athletes: a prospective study.
Amer J Sports Med 1999. 27(6) 699-706
Lambson RB et al. Football cleat design and its effect on
anterior cruciate ligament injuries: a 3-yr prospective study.
AmJSportsMed.1996:24(2)155-9
References
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Mandelbaum BR, Silvers HJ, Watanabe DS. Effectiveness of a
neuromusclular and proprioceptive training program in
preventing anterior cruciate ligament injuries in female
athletes: a 2-year follow-up. Amer J Sports Med. 2005: 33(7)
1003-9
Noyes et al. The Drop-Jump Screening Test. Amer J Sports
Med. 2005: 33(2)197-207