Female athletes are six times as liable as male athletes to be injured playing sport. One of the most common of those is the ACL or anterior cruciate ligament. Dr. Connie Lebrun, MD, sports medicine physician at the Glen Sather Sports Medicine Clinic at the University of Alberta discusses causes and treatment of the injury.

1. ACL Injuries in Women Management and Prevention Dr. Connie Lebrun MDCM, MPE, CCFP, Dip. Sport Med, FACSM Clinical Director Glen Sather Sports Medicine Clinic University of Alberta, Edmonton, Alberta, CANADA

2. Figure 1 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 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. 2

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. 3

4. Figure 2 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 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. 4

5. Figure 3 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 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. 5

6. Figure 4 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 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. 6

7. Figure 5 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 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. ©2010The Amercian College of Sports Medicine. Published by Lippincott Williams & Wilkins, Inc. 7

10. UWO Mustangs

11. Are Women More at Risk?

12. Anatomy of ACL Origin from lateral femoral condyle Insertion to tibial plateau medial to anterior horn of lateral meniscus

13. 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

14. NATIONAL COLLEGIATEATHLETIC ASSOCIATION INJURY SURVEILLANCE SYSTEM (ISS)

15. SportYear ISSBegan Soccer (/) 1984/83 Softball 1984 Ice Hockey () 1984 Field Hockey () 1984 Basketball (/) 1986/86 Spring Football 1986 SportYear ISSBegan Football 1982 Volleyball () 1982 Gymnastics (/) 1983/84 Wrestling 1983 Baseball 1983 Lacrosse (/) 1984/83 Based on exposure rates

17. SOCCERACL Injury Rate, 1989-98 0.32 2.8 X 0.13

19. BASKETBALLACL Injury Rate, 1989-98 0.29 3.5X 0.09

21. Mechanism of ACL Injury Non-contact mechanism (80%) Rapid but awkward stop The position of “no return” ACL tears in 70 ms

23. Anatomic

24. Hormonal

25. BiomechanicalGender Differences?

26. Anterior Cruciate Ligament Injury in the Female Athlete Intrinsic factors: Alignment Hyperextension Physiological rotatory laxity ACL size Notch size and shape Hormonal influences Inherited skills and coordination

27. Anterior Cruciate Ligament Injury in the Female Athlete Extrinsic factors: Strength Conditioning Shoes Motivation

28. Anterior Cruciate Ligament Injury in the Female Athlete Combined (partially controllable): Proprioception (position sense/balance) Neuromuscular activation patterns Sport-specific skills (acquired)

29. Gender Differences?

30. 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.

31. 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

33. to increase awareness of “at risk” population

36. NOT found in male ACLDegroo et al.,Trans Ortho Res Soc, 2001

37. Effects of Hormones - Cellular Mechanisms 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 Seneviratne et al. Trans. Ortho. Res. Soc, 2000

39. mechanically quantified drawer testligament stiffness Estrogen + Relaxin Levine et al.,Ortho Trans, 1999

41. 6 months

42. ligament failure testNo effect of estrogen level on mechanical properties of ACL or MCL Strickland et al.,Trans of Ortho Res Soc, 2000

44. 2 years

45. ligament failure testNo correlation between ACL or Patellar tendon material properties and estrogen levels. Arendt et al.,ISAKOS, 2001

46. Effects of Hormones-Mechanical Properties of Ligaments 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.

47. Hormone Levels and ACL Injuries Estrogen Progesterone

48. Hormone Levels and ACL Injuries Population : 17 Norwegian females (8 on BCP) team handball players menstrual phase at time of N-C ACL injury menstrual history questionnaire Myklebust et al., Scand Med Science and Sport, 1998

50. Trend toward in luteal phaseMyklebust, et al, Scand Med Science and Sport, 1998

52. Date of injury, cycle length, use of oral contraceptives

53. Date of next menstrual cycle used to calculate phase of cycle in which injury occurredNo correlation between cycle phase & NC-ACL injury Boynton et al., AOSSM, 2000

54. 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

55. 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

57. Cannot detect exact location ofhigh risk time intervalArendt et al., Journal of Gender Specific Medicine, 2002

59. Menstrual phase at time of injury

60. Urine specimens within 24 h

61. First day of next cycle

62. Urine analysis for total estrogen, progesterone, and lutinizing hormone metabolitesWojtys et al, AOSSM, 2001

63. LH Levels Progesterone Estrogen Hormone Levels and ACL Injuries Poor correlation between urine metabolites and athlete recollection of cycle Higher number of ACL injuries during mid-cycle No data on how metaboliteswere used to define stages of cycle X = ACL injury LH Concentration levels Progesterone levels (ng/ml) Estrogen levels (pg/ml) 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 X X X X X X X X X X X X X X X X X X X X X X X Wojtys et.al., AOSSM, 2001

65. Saliva sample within 48 hours of injury26/37 (70%) injured ACL in follicular phase . Slaughterbeck et al.,NATA, 2001

66. 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

67. Hormone Research Criticisms: One or two measurements not enough to capture female physiology Normative standards not well defined Small #’s unlikely to capture hormonal variability Most studies have large S.D. bars

68. Conclusion Menstrual cycle phase & musculoskeletal injury Inconclusive data Neuromuscular mechanism (?)

69. Consensus Statements: 1999 Anatomic Risk Factors No consensus on role of the intracondylar notch No consensus on role of ligament size

70. Consensus Statements: 1999Anatomic Risk Factors No consensus on role of anatomic alignment

71. Anatomic Risk Factor ACL Size Size of ACL: less force is required to rupture a smaller ligament

72. Anatomic Risk FactorsACL Size Cadaver knees ( N =16 ) Direct measurement technique Smaller ACL (cross-section) in females compared to males Muneta et al.,AJSM, 1997

73. 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

74. 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

75. 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 controls ACL deficient group had smaller x-sect (31mm) than controls (42.9mm) Willits et al.,AOSSM, 1999

76. THE FAMILIAL PREDISPOSITION TOWARDS TEARING THE ACL: A CASE-CONTROL STUDY K. Flynn BSc C. Pedersen MSc A. Kirkley, MD C. Lebrun, MD Peter J. Fowler, MD The University of Western Ontario, London

77. 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??

78. 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

79. 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

80. Tibial Slope ACL Deficient Knees

81. 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

82. Anatomic Risk Factor Tibial Slope XR measurement case control study: 50 ACL deficient knees to age matched PF knees no significant difference in ACL deficient knees (9.7 degrees) to controls (9.9 degrees) Meister et al.,Amer J Knee Surg, 1997

83. Anatomic Risk Factor Tibial Slope Absolute measurement not contributory (?) Slope plus muscle contractioncombined effect (?)

84. 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.

85. 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

86. ACL Injured on Landing Knee slightly flexed Knee in valgus, external rotation

87. ACL Injured on Landing Knee slightly flexed Knee in valgus, external rotation

88. 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

89. 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

90. Injury Mechanisms – Body Positions

91. 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

92. 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

93. Neuromuscular Prevention Programs Henning - Griffis Program Caraffa Program Wedderkopp’s Program Cincinnati Program Frappier Program (Fargo, N.D.) Santa Monica Program (PEP) Norwegian Awareness Program

94. Norwegian Awareness Program Three types of excercises with progression: Floor Airex balancemat Balance board 5 weeks 2-4 x per week Then 1 x week through the season (Oct-April)

95. Results After 990 Season: All 3 Divisions

96. Conclusion: Only 29% of the teams carried out the program according to the plan Elite teams had the best compliance Exercise quality improved when led by physical therapists Compliance may be improved by: More information Changes in type of excercises Improved info to the coach Sign a contract with the team

97. New and More Sports RelatedTraining 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

98. Floor Exercises – Progression Run wake off Jump and two-leg landing Jump-in fake Turn around jump Jump in with two leg landing

99. Air Mat Progression Receive ball on one leg Jump shot with two leg landing One leg landing Two and one leg ”fight” Jump in with turnround

100. Baps Board Progression: Two leg passes Knee flex two leg and one leg Passes one leg One leg ball dribling wlosed eyes Two leg and one leg ”fight”

101. All Divisions 1999-00: 5 of 23 2000-01: 7 of 17

102. Elite Division 1999-00: 4 of 6 2000-01: 3 of 5

103. Conclusion: An awareness program reduced ACL injuries in Norwegian team handball by 40% overall and 50% at elite level

104. Conclusions Prevention of ACL injuries is possible: Neuromuscular training Focus on knee position Change the plant and cut and landing technique Possibilities for better results with more control of the training

105. Research Needs: Non-Contact ACL Injuries What are strategies for preventing non-contact ACL injuries? What do all these programs have in common?

106. Research Needs: Non-Contact ACL Injuries Proprioception training Identifying at risk motions and positions. Train avoidance techniques when possible Training programs that enhance body control, in particular rotational control of the limb Pelvifemoral muscles (hip extension, hip abduction, abdominals)

107. 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

108. Take “3” to Save the KNEE Accentuate Balanced Body Motion Control Limb Rotation Land with Bent Knee and Hip