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1 ACL Prevention Programs Edward M. Wojtys, M.D. University of Michigan Conflicts of Interest None Disclosures NIH/NIAMS R01 AR Coulter Foundation Grant KIA Research Consultant Center for Organogenesis NFL Injury and Safety Panel Sports Health Editor ACL Injury Cascade Damaging Forces Failed Dynamic Protection ACL Tears Mechanisms of Injury? The Big Black Box Age Distribution? secrets ACL Injury Prevention????? Remains Unopened Adolescent females Danish registry Lind Acta Orthop 2009 Scandanavian registry: Median age ~25 Range= 5-70 years Granan Acta Orthop

2 Risk Factors for Contralateral ACL (Systematic Review 13 Prospective) Contralateral 1 st Time Risk Risk # 1 Risk Factor for Contralateral ACL Injury Return to High Level Activity Sward KSST 2010 Sward KSST 2010 ACL Injury Prevention Programs Kinetics Kinematics Education Compliance Komi Acta Physiol Scand 1978 Females have 100% longer rise times in isometric force development. Gender Differences in Rotational Knee Stiffness 52 NCAA athletes High risk sports of basketball, volleyball, soccer (12 male, 12 female) Low risk sports of cycling, rowing, running (14 male, 14 female) Body-matched male/female pairs for age and sport Strength testing (Biodex) Rotational knee stiffness device Gender Differences in Rotational Knee Stiffness Females increased volitional knee stiffness significantly less than males (p<0.05). Female athletes in pivot sports had lowest volitional increase in knee joint stiffness. Female (pivot sport) 171% Female (non-pivot sport) 198% Male (non-pivot sport) 207% Male (pivot sport) 258% Wojtys JBJS 2003 Wojtys JBJS

3 Engrams Coordinated, efficient muscle effort. ACL Injury Prevention in Alpine Skiing Injury Mechanism Education (Avoiding hazardous positions) Prospective 62% Reduction in ACL Injuries Kottke Arch Phys Med 1980 Ettlinger AJSM 1995 ACL Prevention Kinematics, Kinetics, Education Neuromuscular Prevention (Youth Soccer) Knee, ankle, lower extremity 60 teams - 32 trained 28 control Males & females Cluster randomized trial Stretches, eccentrics, agility, jumping, & balance Emery BJSM 2010 Injury Rate Per 1,000 player hours Trained 2.08 injuries Control 3.35 Neuromuscular Training is Protective! Adolescent & Female Football Stratified cluster randomized trial 230 Swedish clubs (121 intervention) players (12-17 y.o.) 15 min warm-up 2x week (core, balance, allignment) Emery BJSM 2010 Walden BMJ

4 ACL Injuries Intervention 7 (0.28%) Control 14 (0.67%) Reduction in ACL Injury rate 64% Knee Injuries - Soccer 1,506 females (13-19 y.o.) Community based intervention Motor skills, body control, & muscle activation & education Walden BMJ 2012 Kiani Arch Int. Med Intervention 3 injuries Incidence 0.04/1000 player hrs Control 13 injuries 0.20/1000 player hrs 77% reduction knee injuries 90% reduction noncontact Prevention of Knee Injuries Systematic review ( ) 328 studies identified 14 included 5 brace studies Negative 3 shoe cleats / ski boot-binding? 6 prospective, neuromuscular Positive Kiani Arch Int. Med Thacker J Sports Med Phys Fit 2003 Knee Ligament Injury Prevention (KLIP) 577 female athletes (soccer, b-ball, v-ball) 862 controls 20 min / session 2x / week Non randomized coach resistance Pfeiffer JBJS 2006 No Reduction in ACL Injuries! Injury Prevention - Soccer Randomized trial high and low risk Intervention and control Ankle, knee, hamstrings, groin Training compliance (HR) 27.5% Ankle 29.2% Knee 21.1% Hamstrings 19.4% Groin Engebretsen AJSM

5 Effectiveness of ACL Injury Prevention Meta-analysis of prospective controlled studies 909 studies identified 9 included Caraffa 1996 Gilchrist 2008 Heidt 2000 Hewett 1999 Mandelbaum 2005 Petersen 2002 Petersen 2005 Pfeiffer 2006 Sadoghi Studies Scientific quality low Issues blinding, randomization, few matched pairs, drop-out rates Only 1 study with power analysis Study outcome heterogeneity 5/9 soccer Low numbers Pooled Risk Ratio Females % C.I. = Males % C.I. = ACL injury risk reduction significant for females 52% (p=0.021) and males 85% (p<0.001) Meta-Regression? Best Program? Balance Board no effect (p=0.712) Video assistance no effect (0.914) Study heterogeneity At least 10 min 3 x / week F/U duration no effect (0.437) Neuromuscular Year of publication no effect (0.358) On the pooled risk 5

6 Meta-Regression (Training) Preseason vs. playing season reduced risk by 19.1% (p=0.691) ACL Injury Prevention and Performance Enhancement Systematic Review ( ) 57 Studies 42 Programs Sportsmetrics Myklebust 17 Studies KLIP PEP 11 (HOLM) Noyes Sports Health 2012 ACL Injury Incidence Reduction (AE*) Clinical Incidence Rate PEP and Sportsmetrics Injuries *Athletic Performance Improvements Athletes At Risk (N) Noyes Sports Health 2012 ACL Injury Rate Sportsmetrics Injuries Athletic Exposures (AE) Very successful min / 3x week Pre-Season ACL Injury Reduction Improved Athletic Performance Noyes Sports Health

7 Very Good PEP ACL Injury Reduction In-Season 20 min before practice? Athletic Performance? Prevention Programs Landing technique Cutting maneuvers Deceleration Sports Specific Tailored to the Athlete Noyes Sports Health 2012 Artificial Turf vs Grass Prospective Cohort 2020 players (109 teams) Young female football players (2005) Field Turf vs. Grass (NFL) Descriptive Retrospective Study (5360 team/games) Risk of Acute Ankle/Knee Injury was Similar! Injury Rate 67% on Field Turf Steffen BJSM 2007 Hershman AJSM 2012 Compliance Summary Athletic Performance Injury Prevention Injury prevention hampered by lack of ACL injury mechanism understanding Balance Still not sure what Sportsmetrics, PEP, and other successful programs change? 7

8 ACL Injury Prevention (Meta-Analysis) Thank You Plyometric Strength Training Balance Training *Most effective females (<18 yo) soccer Yoo KSST 2010 Warm-up Program (cluster randomized trial) 1892 female footballers (13-17 y.o.) Foot, ankle, leg, knee, thigh, groin, & hip Strength, awareness, & NM control Risk of all injuries, severe & overuse, was reduced! (Lower extremity injury rate did not change) ACL-R Risk Factors Activity Level & Graft Type Case-control 21 pts 42 matched Univariate logistic regression Low vs. high activity OR 5.53 (95% C.I ) Allo vs. auto OR 5.56 (95% C.I ) Soligard BMJ 2008 Borchers AJSM 2009 Goals Hamstring Training Enhanced condition Eccentric > Concentric Prevent muscle fatigue Hamstring fatigue Transverse plane Control Deficits (Improving quad/hamstring) (* Professional soccer players) Nyland JAT 1999 Mjolsnes SJ Med Sci Sports

9 Gluteal Training (Abductors, Extensors, External Rot.) Plyometric training Core Pertebation training Dynamic L.E. control & positioning at ground contact Body sway control Chimera JAT 2004 Jamison MSSE 2012 Hamstring Strength Knee Injuries Alpine Skiing Concentric vs. eccentric 21 well trained male soccer players 2x6 reps 3x(8-12) reps x2/weeks load x 6 weeks 11% in eccentric torque (60) Mjolsnes Scand JMS Sports 2004 No in concentric Education program ( ) 20 intervention Ski areas 22 control 179 serious injuries 62% reduction with education Ettlinger AJSM 1995 Contra vs. Ipsilateral ACL Injury 63 ACL-R 39 controls 12 month f/u 16 ACL-R, 1 control ACL Female Athletes 4x male risk 2 nd ACL 6x male risk contra ACL * Female ACL-R 16x injury rate (controls) 4x ACL Paterno Clin J. Sport Med 2012 Paterno Clin J. Sport Med

10 ACL Retear and Contralateral Injury Risk Prospective cohort (Level II) 2y data 235(273) 86% 7 retears (3%) 7 contra (3%) ACL Prevention Success Rates Decrease in ACL tears Ekstrand 75% Vermont 62% Cincinnati (Sportsmetrics) 72% Wedderkopp 71-80% Caraffa 87% Santa Monica (PEP) 88%, 74% Soderman 0% Moon AJSM 2007 Education Injury Situation Avoid hazards (proper form, positioning, anticipation) Neuromuscular Protection PEP Program 20 min warm-up (video) 2-3 times/week for 12 weeks Avoidance techniques Stretch and strengthen Plyometrics Soccer agilities Dissipate damaging forces Mandelbaum AOSSM 2002 PEP Results 1041 soccer trainees 0.2 injuries/player 1902 soccer controls 1.7 injuries/player Protective System Sensory receptor outflow causes activation of muscle efferents generating stabilizing muscle co-contractions % in ACL Injuries a % in ACL Injuries Mandelbaum AOSSM 2002,

11 Pertubation Training Protective System Protective Muscle Contractions Selective Muscle Use Patterns co-contraction (Q-H-G) muscle stretch reflex Knee Joint Resistance to Deformation Always present Intrinsic Stiffness First line of defense Extrinsic Stiffness Dependent upon the excitation provided by the alpha and gamma motoneurons. (Relaxed) Can be modified with training. Gender Differences in the Contributions of the Musculature to Knee Shear Stiffness Edward M Wojtys, MD James A. Ashton-Miller, Ph.D Laura J. Huston, M.S. % Increase in Stiffness Males 473% Females 217% (p=0.003) JBJS,

12 Regression Model Strength was not the predominant contributor to knee stiffness. Stiffness = x x x 3 + ß X 1 = muscle strength X 2 = gender X 3 = subject s height ß = constant = 51.9 (p=0.974) (p=0.049) (p=0.666) (p=0.576) Granata J Elect & Kines 2002 Gender differences in active musculo - skeletal stiffness Female subjects demonstrated a 56-73% reduced active limb stiffness relative to the male subjects Quads --- Men --- Women Hamstrings Granata, Leg stiffness in the female subjects was approximately 77% that seen in males. 2. Body mass did not adequately explain the gender effect. Stiffness Results (kn/m) Hopping Freq. Males Females % Diff preferred 26 (9) 19 (8) * 27% * 2.5 Hz 31 (8) 24 (5) * 23% * 3.0 Hz 43 (8) 35 (7) * 19% * * males significantly greater (p<0.05) Gender Differences in the Muscular Protection of the Knee Among BMI- Matched Athletes JBJS May 2003 Study Hypothesis: No gender differences exist in internal tibialfemoral rotation when maximally contracting knee joint musculature. Ideal ACL Training Program Rotatory Laxity of the Knee 1. Stimulates joint and muscle receptors to induce high level of Q-H-G co-contractions. 2. Improves whole body and single joint positions to loads on joints. 3. Plyometrics to improve MRT &TPT. 4. Skill training to isolate ideal movements than will generate lowest joint moments and best position for cutting and jumping. 80% reduction in rotatory laxity with 938 N of compressive force Lloyd JOSPT 2001 Wang & Walker JBJS

13 Varus-Valgus Knee Stiffness % increase with isometric contraction 1000% increase in conditioned athletes Markolf JBJS 1976 Causes? Background Multifactorial! Hormones not understood Worrisome Anatomy difficult to change Muscle Function training programs?? mechanism of action Lengthening? Isometric? Shortening? 1 0 v t = 0 t = 200 msec Effect of Hamstrings Lengthening hamstrings produced the lowest relative ACL strain Configuration Mean (SD) Effect of Hamstrings Lengthening hamstring condition significantly decreased anteromedial ACL relative strain in this jump landing model Max ACL strain (%) Max impact force (N) Max quad force (N) Max medial hamstring force (N) Max lateral hamstring force (N) Shortening 3.0 (1.1) 1755 (275) 1579 (203) 168 (68) 183 (62) Lengthening 0.8 (0.6) 2093 (370) 1161 (231) 338 (118) 394 (83) Isotonic 3.6 (1.1) 1777 (256) 1546 (186) 92 (29) 103 (31) No hamstring 2.9 (1.3) 1702 (224) 1514 (169) N/A N/A Withrow ORS 2006 Withrow ORS

14 /12/2013 For a given increase in knee flexion angle, an increase in hip flexion angle exists that will lengthen the hamstring muscle-tendon unit (MTU) in a jump landing. Lengthening Contraction 1.6 Hypothesis Isometric or Shortening contraction Methods 3 cadavers Open dissection and digitization of origins and insertions of BF, SM and ST MTU Certus system kinematic measurements Calculate hamstring MTU length for knee angles between 0-90o at 0, 30 or 60o hip angles (3 trials each) l Hamstring = f ( θ Knee, θ Hip ) Hamstring Length (cm) C a d a v ebf r # 1 - B F K n e e F le x i o n A n g le ( d e g ) Initial Knee & Hip Angle 30 At Landing Hip 15 Knee 21 Pflum 2004 Forward Hop Hip Russell et al. J. Athl. Train Angle Conclusions Pooled Risk 1. Hypothesis supported: A hamstring lengthening state can indeed occur - when the change in hip angle exceeds 57% of the change in knee angle. 2. Using drop landing test data, simulations suggest the hamstring MTU act in a quasiisometric state during a drop landing 3. Reducing the knee flexion or increasing the hip flexion will lengthen hamstring MTU to help protect ACL, and vice versa. Risk Ratio 0.38 Prevention programs reduced risk of ACL tear by 62% 14

15 Pooled Risk - Gender Female risk reduction 52% Male risk reduction 85% Number needed to treat to prevent 1 ACL tear was