acl injuries in women athletes 2011
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Dr. Connie Lebrun MDCM, MPE, CCFP,
Dip. Sport Med, FACSM
Clinical Director Glen Sather Sports Medicine Clinic
University of Alberta, Edmonton, Alberta, CANADA
ACL Injuries in WomenManagement and
Prevention
©2010The Amercian College of Sports Medicine. Published by Lippincott Williams & Wilkins, Inc. 2
Figure 1Complex Integrative Morphological and Mechanical Contributions to ACL Injury Risk.McLean, Scott; Beaulieu, Melanie
Exercise & Sport Sciences Reviews. 38(4):192-200, October 2010.DOI: 10.1097/JES.0b013e3181f450b4
Figure 1 . Combined effects of fatigue and decision making on key knee joint biomechanical parameters during a high-impact single leg landing task. As fatigue progressed, statistically significant (P Med Sci Sports Exerc. 2009; 41(8):1661-72. Copyright (C) 2009 Lippincott Williams & Wilkins. Used with permission.]
©2010The Amercian College of Sports Medicine. Published by Lippincott Williams & Wilkins, Inc. 3
TABLE.Complex Integrative Morphological and Mechanical Contributions to ACL Injury Risk.McLean, Scott; Beaulieu, Melanie
Exercise & Sport Sciences Reviews. 38(4):192-200, October 2010.DOI: 10.1097/JES.0b013e3181f450b4
TABLE. Research studies investigating explicit links between morphological and knee joint biomechanical factors associated with anterior cruciate ligament (ACL) injury risk.
©2010The Amercian College of Sports Medicine. Published by Lippincott Williams & Wilkins, Inc. 4
Figure 2Complex Integrative Morphological and Mechanical Contributions to ACL Injury Risk.McLean, Scott; Beaulieu, Melanie
Exercise & Sport Sciences Reviews. 38(4):192-200, October 2010.DOI: 10.1097/JES.0b013e3181f450b4
Figure 2 . A custom designed manual loading device was used to apply combined 3D loads to male and female cadaveric knee specimens (A). Using these and resultant ligament strain data, specimen-specific regression models were developed that could predict peak anterior cruciate ligament (ACL) strain magnitudes to within 0.51% +/- 0.01% and 0.52% +/- 0.06% of measured data, and within 0.61% +/- 0.11% and 0.57% +/- 0.05% of validation data (not used in model development) respectively (B). Application of combined valgus (45 Nm), internal rotation (20 Nm) and compressive (300 N) loads at a fixed knee flexion angle (40 deg) and three discrete anterior tibial shear load magnitudes (50 N, 100 N and 150 N) resulted in predicted peak female ACL strains that were significantly greater than male ACL strain values (C). [Adapted from Mizuno K, Andrish JT, van den Bogert AJ, McLean SG. Gender dimorphic ACL strain in response to combined dynamic 3D knee joint loading: implications for ACL injury risk. Knee. 2009; 16(6):432-40. Copyright (C) 2009 Elsevier. Used with permission.]
©2010The Amercian College of Sports Medicine. Published by Lippincott Williams & Wilkins, Inc. 5
Figure 3Complex Integrative Morphological and Mechanical Contributions to ACL Injury Risk.McLean, Scott; Beaulieu, Melanie
Exercise & Sport Sciences Reviews. 38(4):192-200, October 2010.DOI: 10.1097/JES.0b013e3181f450b4
Figure 3 . Associations between key knee joint anatomical indices and peak stance phase knee joint biomechanical variables during a single-leg landing task. Specifically, peak anterior knee joint reaction force was significantly positively correlated with lateral posterior tibial slope (LTS) (A). Peak knee joint internal rotation angle was significantly positively correlated with the ratio between medial and lateral posterior tibial slopes (MTS:LTS) (B). Peak knee abduction angle was significantly positively correlated with both MTS:LTS and the ratio between the tibial plateau width and the intercondylar distance (TPW:ICD) (C). [Adapted from McLean SG, Lucey SM, Rohrer S, Brandon C. Knee joint anatomy predicts extreme in vivo knee joint mechanics during single leg landings. Clin Biomech. 2010;In press. Copyright (C) 2010 Elsevier. Used with permission.]
©2010The Amercian College of Sports Medicine. Published by Lippincott Williams & Wilkins, Inc. 6
Figure 4Complex Integrative Morphological and Mechanical Contributions to ACL Injury Risk.McLean, Scott; Beaulieu, Melanie
Exercise & Sport Sciences Reviews. 38(4):192-200, October 2010.DOI: 10.1097/JES.0b013e3181f450b4
Figure 4 . Conceptual model depicting integrative morphological and biomechanical contributions to knee joint and anterior cruciate ligament (ACL) loading during high-impact landing maneuvers. Explicit combinations of postural alignment and knee joint anatomical and laxity factors are posited to implicate within the ACL injury risk via the generation of large knee joint and resultant ACL load states. For the associated figure, ABd = abduction; IR = internal rotation; Ant Shear = anterior tibial shear; Fx = force in the x-axis direction; Fy = force in the y-axis direction; Fz = force in the z-axis direction; Mx = moment about the x-axis; My = moment about the y-axis; Mz = moment about the z-axis.
©2010The Amercian College of Sports Medicine. Published by Lippincott Williams & Wilkins, Inc. 7
Figure 5Complex Integrative Morphological and Mechanical Contributions to ACL Injury Risk.McLean, Scott; Beaulieu, Melanie
Exercise & Sport Sciences Reviews. 38(4):192-200, October 2010.DOI: 10.1097/JES.0b013e3181f450b4
Figure 5 . Surrogate (integrative forward dynamic and finite element) modeling techniques proposed to successfully investigate anterior cruciate ligament (ACL) causality based on integrative neuromechanical and morphological factors. Systematic and/or random perturbations can be applied at each level of the modeling pipeline, based on quantified variations in each measure, to determine ACL injury risk arising through individual-specific neuromechanical and morphological vulnerabilities.
Are Women More at Risk?
Anatomy of ACL
Origin from lateral femoral condyle
Insertion to tibial plateau medial to anterior horn of lateral meniscus
ACL Injury
“Commonest cause of the ex-athlete”
1 in 10 female athletes (N.C.A.A.)
2-6 times higher incidence than males in same sport
NATIONAL COLLEGIATEATHLETIC ASSOCIATION
INJURY SURVEILLANCE SYSTEM (ISS)
Sport Year ISSBegan
Soccer (/) 1984/83
Softball 1984
Ice Hockey () 1984
Field Hockey () 1984
Basketball (/) 1986/86
Spring Football 1986
Sport Year ISSBegan
Football 1982
Volleyball () 1982
Gymnastics (/) 1983/84
Wrestling 1983
Baseball 1983
Lacrosse (/) 1984/83
Based on exposure rates
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
'89 '90 '91 '92 '93 '94 '95 '96 '97 '98 AllYears
Inju
ry R
ate
(per
100
0 A
-E)
Women
Men
SOCCERACL Injury Rate, 1989-98
0.32
0.13
2.8 X
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
'89 '90 '91 '92 '93 '94 '95 '96 '97 '98 AllYears
Inju
ry R
ate
(per
100
0 A
-E)
Women
Men
BASKETBALLACL Injury Rate, 1989-98
0.29
0.09
3.5X
Mechanism of ACL Injury
Non-contact mechanism (80%)
Rapid but awkward stop
The position of “no return”
ACL tears in 70 ms
Gender Differences?
Risk Factors:Environmental
Anatomic
Hormonal
Biomechanical
Anterior Cruciate Ligament Injury in the Female Athlete
Intrinsic factors:AlignmentHyperextensionPhysiological rotatory laxityACL sizeNotch size and shapeHormonal influencesInherited skills and coordination
Anterior Cruciate Ligament Injury in the Female Athlete
Extrinsic factors:StrengthConditioningShoes Motivation
Anterior Cruciate Ligament Injury in the Female Athlete
Combined (partially controllable):Proprioception (position sense/balance)Neuromuscular activation patternsSport-specific skills (acquired)
Gender Differences?
Non-Contact Anterior Cruciate Ligament Injuries: Risk Factors
and Prevention Strategies
A Consensus Conference held at Hunt Valley, Maryland on June 10, 1999
Sponsored by AAOS, AOSSM, NCAA, and NATA
Organized by Letha Y. Griffin, M.D., Ph.D.Elizabeth A. Arendt, M.D.
Hunt Valley Consensus ConferenceJune 1999
Reviewed research to date: Anatomic risk factors Hormonal risk factors Biomechanical/neuromuscular risk factors
Reviewed videos on non-contact ACL injuries
Reviewed existing neuromuscular programs
GOALS:
to increase awareness of “at risk” population
to stimulate increased research efforts
Hunt Valley Consensus ConferenceJune 1999
Hunt Valley Consensus Conference: June 1999
HORMONAL RISK FACTORS
No consensus that sex specific hormones play a role in increased ACL injuries in females
No evidence to recommend modification of sports or hormonal modification for females
Remains a “fertile” area for future research
Existence of Hormone Receptors in Ligaments
Relaxin receptor sites :Found in female ACLNOT found in male ACL
Degroo et al.,Trans Ortho Res Soc, 2001
Model: human ACL, 5 & 5 cell culture
Model: Sheep ACL fibroblasts Cyclic estrus function Estrogen receptors
present in sheep ACL fibroblasts
No effect of physiologic levels of estrogen on cell proliferation or collagen synthesis
Effects of Hormones - Cellular Mechanisms
Seneviratne et al.Trans. Ortho. Res. Soc, 2000
Effects of Hormones-Mechanical Properties of Ligaments
Model: mouse knee jointmechanically quantified drawer test
Estrogen + Relaxin ligament stiffness
Levine et al.,Ortho Trans, 1999
Effects of Hormones-Mechanical Properties of Ligaments
Model: sheep38 animals (38 ACL/10MCL)6 monthsligament failure test
No effect of estrogen level onmechanical properties of ACL or MCL
Strickland et al.,Trans of Ortho Res Soc, 2000
Effects of Hormones-Mechanical Properties of Ligaments
Model: primate26 animals (26 ACL/26 PT)2 yearsligament failure test
No correlation between ACL or Patellar tendon material properties and estrogen levels. Arendt et al.,
ISAKOS, 2001
Estrogen and progesterone receptor sites have been reported in human ACL cells.
Relaxin receptor sites have been reported in female ACL cells.
The effect of relaxin, or relaxin plus estrogen may merit further investigation.
Effects of Hormones-Mechanical Properties of Ligaments
EstrogenProgesterone
Hormone Levels and ACL Injuries
Population : 17 Norwegian females (8 on BCP)team handball players
menstrual phase at time of N-C ACL injurymenstrual history questionnaire
Myklebust et al., Scand Med Science and Sport, 1998
Hormone Levels and ACL Injuries
Fewer injuries occurred during mid-cycle.
Trend toward in luteal phase
Myklebust, et al, Scand Med Science and Sport, 1998
Hormone Levels and ACL Injuries
No correlation between cycle phase & NC-ACL injury
Boynton et al.,AOSSM, 2000
Population : 61 female recreational skiers
Date of injury, cycle length, use of oral contraceptives
Date of next menstrual cycle used to calculate phase of cycle in which injury occurred
Hormone Levels and ACL Injuries
Population : 83 College female varsity athletes.
(25 on birth control pills) Menstrual phase at time of N-C ACL No data on onset of next menses
No significant difference in NC-ACL injury & day of menstrual cycle.Trend toward in follicular stage
Arendt et al.,Journal of Gender Specific Medicine, 2002
Hormone Levels and ACL Injuries
Centered moving average
Smooth out time dependency of the number of injuries
Arendt et al., Journal of Gender Specific Medicine, 2002
Hormone Levels and ACL Injuries
Arendt et al., Journal of Gender Specific Medicine, 2002
Cannot detect exact location ofhigh risk time interval
Non-linear regression model
There is a significant difference in the time dependency of the number of injuries
Hormone Levels and ACL Injuries
Population : 65 females (8 on OCP)Sports related NC-ACL injuryMenstrual phase at time of injuryUrine specimens within 24 hFirst day of next cycleUrine analysis for total estrogen, progesterone, and
lutinizing hormone metabolites
Wojtys et al,AOSSM, 2001
Hormone Levels and ACL Injuries
LH Levels
Progesterone
Estrogen
X X X X X X X X
X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X XX X X X X X X X X X X X X X X X X X X X X X
LH
Con
cent
rati
on
leve
lsE
stro
gen
leve
ls
(pg/
ml)
Pro
gest
eron
e le
vels
(n
g/m
l)
X = ACL injury Poor correlation between urine metabolites and athlete recollection of cycle
Higher number of ACL injuries during mid-cycle
No data on how metabolites were used to define stages of cycle Wojtys et.al.,
AOSSM, 2001
Hormone Levels and ACL Injuries
Population : 35 females (25 College / 12 H.S.)
Sports related NC-ACL injurySaliva sample within 48 hours of injury
26/37 (70%) injured ACL in follicular phase
.
Slaughterbeck et al.,NATA, 2001
Hormone Levels and ACL Injuries
Hormones and Tissue Laxity
Population: 26 high school female athletes Normal menstrual cycle Prospective single blinded 8 week study KT-1000 measurements taken prior to practice Repeated measurement of KT-1000 over 8 weeks Menstrual cycles charted No difference in KT-1000 with phase of the
menstrual cycle
Karageanes et al.,Clin J Sports Med, 2000
Hormone Research
Criticisms:One or two measurements not enough
to capture female physiologyNormative standards not well definedSmall #’s unlikely to capture hormonal
variabilityMost studies have large S.D. bars
Conclusion
Menstrual cycle phase & musculoskeletal injury
Inconclusive data
Neuromuscular mechanism (?)
Consensus Statements: 1999 Anatomic Risk Factors
No consensus on role of the intracondylar notch
No consensus on role of ligament size
Consensus Statements: 1999Anatomic Risk Factors
No consensus on role of anatomic alignment
Anatomic Risk Factor ACL Size
Size of ACL: less force is required to rupture a smaller ligament
Anatomic Risk FactorsACL Size
Cadaver knees ( N =16 )Direct measurement techniqueSmaller ACL (cross-section) in
females compared to males
Muneta et al.,AJSM, 1997
Anatomic Risk Factor ACL Size
Measured ACL width on MRI
Males ACL (6.1mm) > females ACL (5.2mm) Did not control for height and weight
Staubli etal.,Arthroscopy, 1999
Anatomic Risk Factor ACL Size
Measured ACL (cross-section) on CT scan
Male ACL (47.1mm) > female ACL (35.1mm)
Controlled for height and weight
Jackowski et al.,(Thesis, London, Ont.) 2001
Anatomic Risk Factors ACL Size
Measured ACL cross-section on MRI Case control study:
matched for gender, age, and activity 20 F ACL deficient knees: contralateral
knee compared to 20 controlsACL deficient group had smaller x-sect
(31mm) than controls (42.9mm)Willits et al.,AOSSM, 1999
THE FAMILIAL PREDISPOSITION
TOWARDS TEARING THE ACL: A CASE-CONTROL STUDY
K. Flynn BSc C. Pedersen MSc
A. Kirkley, MDC. Lebrun, MD
Peter J. Fowler, MDThe University of Western Ontario,
London
Anatomic Risk FactorsACL Size
Based on data to date it appears that the increased rate of ACL tears seen in patients with narrower notches may simply be a manifestation of a smaller ACL.
Is the smaller ACL appropriate for the size / strength of the individual ????
If no -- is it due to gender, hormones, training??
Anatomic Risk Factor Tibial Slope
Tibial Slope: in the “quads active” mechanism of ACL injury, the tibia is planted & the quadriceps contracts resulting in sufficient force to cause excessive posterior translation of the femur in relation to the tibia, resulting in tearing of the ACL.
The greater the tibial slope the easier it is for the femur to “slide” down the slope thus tearing the ACL
Anatomic Risk Factor Tibial Slope
There is a 6 mm increase in anterior tibial translation for every 10 degree increase in anterior tibial slope
DeJour and Bonnin,JBJS, 1994
Tibial Slope ACL Deficient Knees
Anatomic Risk Factor Tibial Slope
Tibial slope measured on CT scan
No difference in males (8.3 degrees) vs. female (8.1 degrees) varsity athletes
Jackowski et al.,(Thesis, London, Ont.) 2001
Anatomic Risk Factor Tibial Slope
XR measurementcase control study: 50 ACL deficient
knees to age matched PF kneesno significant difference in ACL
deficient knees (9.7 degrees) to controls (9.9 degrees)
Meister et al.,Amer J Knee Surg, 1997
Anatomic Risk Factor Tibial Slope
Absolute measurement not contributory (?)
Slope plus muscle contraction combined effect (?)
Prevention Strategies for Anatomic Risk Factors
Anatomic risk factors are difficult to alter
Little agreement regarding which anatomic factors may be significant, hence no prevention strategies recommended at this time.
Hunt Valley Consensus ConferenceVideos of ACL Injuries
54 videos of ACL injuries were collected in preparation for consensus conference
22/54 in basketball: 15 women, 5 men, 2 ?
Mechanism of injury: jump stop, jump landing, sudden deceleration
ACL Injured on Landing
Knee slightly flexed
Knee in valgus, external rotation
ACL Injured on Landing
Knee slightly flexed
Knee in valgus, external rotation
Videos of ACL InjuriesConclusions
Most common positions at injury were landing from a jump, jump stop, sudden deceleration
Injured leg was usually not extended, but less than 30º flexion
Research Needs: Non-Contact ACL Injuries
What is the mechanism of injury in non-contact injuries to the ACL?
Video data conflicts with in vitro data concerning ACL failure mechanisms
Injury Mechanisms – Body Positions
Knee Biomechanics (in vitro)
External loads of valgus and external rotation do not load the ACL between 100 and 300 flexion
Quadriceps activation can load the ACL between 100 and 300 flexion; this is increased if no hamstrings activation
Consensus Statements: 1999Biomechanical Risk Factors
At this time, neuromuscular factors appear to be the most important reason for the differing ACL injury rates between males and females
Strong quadriceps activation during eccentric contraction a major factor in injury to ACL
Neuromuscular Prevention Programs
Henning - Griffis ProgramCaraffa ProgramWedderkopp’s ProgramCincinnati ProgramFrappier Program (Fargo, N.D.)Santa Monica Program (PEP)Norwegian Awareness Program
Norwegian Awareness Program
Three types of excercises with progression:
1. Floor
2. Airex balancemat
3. Balance board 5 weeks 2-4 x per week Then 1 x week through the season
(Oct-April)
Results After 99\00 Season: All 3 Divisions
ACL-skader Elite, 1. og 2. divisjon
Måned
J uni J uli Aug Sept Okt Nov Des J an Feb Mars Apr Mai
Antall A
CL s
kader
0
5
10
15
20
25
30
35
1998-1999
1999-2000
Conclusion:
Only 29% of the teams carried out the program according to the planElite teams had the best compliance
Exercise quality improved when led by physical therapists
Compliance may be improved by:More informationChanges in type of excercises Improved info to the coachSign a contract with the team
New and More Sports Related Training Programs
Handball related excercises Fakes Two-leg landing Less static excercises
Increased skill-level Increased number of
two-persons drills Increased knowledge
and motivation for players
Floor Exercises – Progression
Run w\take off Jump and two-leg
landing Jump-in fake Turn around jump Jump in with two
leg landing
Air Mat Progression
Receive ball on one leg
Jump shot with two leg landing
One leg landingTwo and one leg
”fight”Jump in with
turnround
Baps Board Progression:
Two leg passes Knee flex two leg
and one leg Passes one leg One leg ball
dribling w\closed eyes
Two leg and one leg ”fight”
All Divisions
ACL-skader Elite, 1. og 2. divisjon
Month
Aug Sept Oct Nov Dec J an Feb March Apr May
No of ACL in
jurie
s
0
5
10
15
20
25
30
35
1998-1999
1999-2000
2000-2001
1999-00: 5 of 23
2000-01: 7 of 17
Elite Division
ACL-skader Elite, 1. og 2. divisjon
Month
Aug Sept Oct Nov Dec J an Feb March Apr May
No of ACL in
jurie
s
0
2
4
6
8
10
12
14
1998-1999
1999-2000
2000-2001
1999-00: 4 of 6
2000-01: 3 of 5
Conclusion:
An awareness program reduced ACL injuries in Norwegian team handball by 40% overall and 50% at elite level
Conclusions
Prevention of ACL injuries is possible:Neuromuscular trainingFocus on knee positionChange the plant and cut
and landing technique
Possibilities for better results with more control of the training
Research Needs: Non-Contact ACL Injuries
What are strategies for preventing non-contact ACL injuries?
What do all these programs have in common?
Research Needs: Non-Contact ACL Injuries
Proprioception trainingIdentifying at risk motions and
positions. Train avoidance techniques when possible
Training programs that enhance body control, in particular rotational control of the limbPelvifemoral muscles (hip extension, hip
abduction, abdominals)
Research Needs: Non-Contact ACL Injuries
What specific neuromuscular factor accounts for the difference in ACL injury incidence between males and females? - most studied risk factor to
date is GENDER
Take “3” to Save the KNEE
Accentuate Balanced Body Motion
Control Limb Rotation
Land with Bent Knee and Hip
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