ACL injury screening and prevention CATS meeting 2016

The Epidemic of ACL Tears in Female Youth Athletes

Screening Tools to Help Prevent ACL Injury Aaron Gray, MD@MizzouSportsDocUniversity of Missouri

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DisclosuresI have received a Mizzou Advantage grant for research of ACL injury risk screening with video game technology.I have no other financial disclosures relevant to this talk.

Matthew Busch, Missourian

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OverviewEpidemiology of ACL Tears in AthletesFactors for the Female ACL Tear EpidemicNeuromuscular Deficits in Female AthletesScreening Tests for ACL Injury RiskACL Injury Prevention Programs

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About half of ACL injuries were in competitions and the injury rate was higher for competitions compared to practices.

Athletic ExposuresOne athlete participant in one practice or game equals one athletic exposure

Example: 25 athletes completing one practice is 25 athletic exposures

Incidence of ACL Injuries per 10,000 Athletic Exposures in Collegiate Athletes4.1x2.8xStanley et al. AJSM, 2016.

The Epidemic of Female ACL Tears

www.daytondailynews.com

Epidemic of Female ACL Ruptures in USFemale athletes have 4-6x increased risk of ACL injuries than males in similar cutting sports

Since Title IX was passed in 197210x increase in participation in girls HS athletics5x increase in female participation in collegiate sportsArendt, et al. J Athl Train, 1999.NCAA (2002) and NFHS (2009) published data

ACL tear risk may be up to 9x male counterparts8

Epidemic of Female ACL Ruptures in USEstimated 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

In 2001 estimated 38,000 ACL injuries in girls and women at cost of approximately 650 million annually Brukner & Khan. Clinical Sports Medicine, 4th ed. 2012.Toth & Cordasco. J Gend Specif Med 2001.

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ACL Injury StatisticsSoccer was highest mechanism of injury (26.6%) in Kaiser Permanente ACL registry

ACL tears peak at age 16 in female athletes

Maletis, et al. J Bone Joint Surg Am 2011.

Female athletes who play soccer or basketball year-round have an annual ACL tear rate of 5%Prodromos, et al. Arthroscopy 2007.

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Gender Disparity is Likely MultifactorialIntrinsic variables with gender differencesAnatomicHormonal Neuromuscular

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Anatomic DifferencesProposed gender differences includeSmaller size and different shape of intercondylar notchSmaller ACL within smaller notchWider pelvis and greater Q angleGreater ligament laxitySince little can be done to modify these anatomical findings, focus has moved to what can be changed

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Hormonal DifferencesHormonal effects on the musculoskeletal system is a complex process

Most studies suggest increased risk of ACL injury in preovulatory phase of menstrual cycle

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Hormonal DifferencesNo evidence that oral contraceptives decrease ACL injuries

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Neuromuscular Deficits in Female Athletes4-6 inch growth spurt around 10-11 years oldCenter of mass rises through pubertyAfter growth spurt female adolescents do not gain neuromuscular spurt that males achieve

Huston & Wojtys. AJSM 1996.

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Post-Pubertal Differences in Knee Abduction Angle during Landing Between Genders

Ford et al. Med Sci Sports Ex 2010.

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).16

What Usually Happens in a Non-contact ACL injury?60-80% of ACL injuries are non-contactTwo common mechanisms

LandingCuttingKrosshaug et al. AJSM 2007.

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Characteristics of ACL tears in FemalesDynamic knee valgus on landingKnee is relatively straight on landingMost or all of weight is on one legTrunk is tilted laterally (center of mass is outside feet)

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Olsen et al. AJSM 2004.

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What usually happens in a non-contact ACL injury?

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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.23


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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.26


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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.29


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Four Neuromuscular Imbalances in FemalesLigament DominanceQuadriceps DominanceLeg DominanceTrunk Dominance (Core Dysfunction)Hewett et al. NAJSPT, 2010.

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Ligament DominanceMuscles do not sufficiently absorb ground reaction forcesJoint and ligaments must absorb high forces over a short period of timePosterior kinetic chain (gluteals, hamstrings, gastrocnemius, soleus) must be recruited to avoid ligament dominance

Newtons 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. 33

Ground Reaction ForcesGRF are directed toward the center of mass in the trunk of the athleteLateral trunk movement forces lower leg into dynamic valgus

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Quadriceps DominanceDecreased hamstring strength and recruitmentFemales activate quadriceps more than males for initial knee stabilization

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Quadriceps DominanceFemales land with less knee flexion than males3x less posterior kinetic chain activation during landing than size matched malesHewett et al. AJSM 1996.

Attempt to stabilize joint with quadriceps which results in anterior tibial translationQuadriceps contraction increases ACL strain between 10 and 30 of knee flexion

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Knee Stability OptionsQuadricepsSingle insertionPatellar tendon into tibial tubercleLess flexion on landingAnterior tibial translation increases ACL stress

Posterior Chain MusclesMultiple, varied insertionsMedial and lateral tendons give frontal plane controlMore flexion on landingPrevents anterior tibial translation which decreases ACL stress

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Leg DominanceFemales tend to be more one-leg dominant than malesDuring an ACL injury most (or all) weight is on one legAthletes with increased asymmetry have greater risk of injury

Hewett, et al. AJSM 2005.

KOMU.com

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Trunk Dominance (Core Dysfunction)Athletes who had deficits of active core proprioceptive had greater risk of ACL injury

Zazulak, Hewett, et al. AJSM 2007.

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Screening for ACL Injury Risk

Why screening tests to predict injury do not work and probably never will: a critical reviewThree steps needed to validate a screening test to predict and prevent sports injuries

Prospective cohort study to identify risk factor(s) and define cut-off value(s)Validate test and cut-off value in multiple cohortsRandomized controlled trial to test effect of combined screening and intervention program Bahr R. BJSM Published Online First, April 25, 2016.

Test athletes preseason and follow for injuries and find associationsThe question is how well the test predicts who becomes injured and who becomes healthy

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AJSM, 2005.

AOSSM award for outstanding clinical or laboratory based research efforts that are applicable to the understanding, care or prevention of injuries in sports42

205 female HS athletes in soccer, basketball and volleyball prospectively measured for neuromuscular control with 3D motion analysis

Hewett et al. AJSM 2005.

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9 out of 205 girls suffered ACL tears

8.4 more dynamic valgus 7.6 more dynamic valgus 10.5 less knee 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 flexion44

9 out of 205 girls suffered ACL tears

External Knee Abduction MomentKnee Abduction Angle at Initial Contact

8.4 degrees more dynamic valgus on initial contact7.6 degrees more dynamic valgus at peak flexion10.5 degrees less knee flexion at peak flexion45

Norwegian professional female handball and soccer athletes completed a DVJ in preseason

Take Home: Medial knee displacement during the DVJ was only statistically significant predictor of ACL injury risk in Norweigian professional female handball & soccer players with avg. age 21 y/o

Older population than Hewitts 2005 study and likely already participating in injury prevention program

Landing Error Scoring System JUMP-ACL studySimilar to Hewitts Drop Vertical Jump protocol except:2 video cameras are used (frontal and side view) instead of marker based motion captureParticipants jump to a distance 50% of their height and immediately perform a maximum vertical jump

Padua, et al. AJSM 2009.




Landing Error Scoring System JUMP-ACL study2691 subjects who were incoming freshman at 3 large US military academies

Simultaneously analyzed with sophisticated laboratory system and inexpensive field analysis system (LESS)

Results: Valid and reliable tool for identification of subjects with landing errors in multiple planesPadua, et al. AJSM 2009.

Landing Error Scoring System as a Screening Tool for ACL Injury in Elite Youth Soccer AthletesPadua et al. J Athletic Training 2015.

829 elite-youth soccer athletes (348 boys, 481 girls)Age= 13.9 1.8 years, age range = 11 to 18 yearsFollowed for 1217 athlete-seasons7 non-contact ACL tears occurred

Uninjured participants had lower LESS scores (4.43 1.71) than injured participants (6.24 1.75; P = .005)

Analyses of Landing Mechanics in Division I Athletes Using the Landing Error Scoring SystemJames et al. Sports Health, 2015.

34 Division 1 male and soccer athletes performed a drop-landing task and were scored with LESS and lower extremity injuries were tracked during season

No statistically differences found in LESS scores in those with & without injury history.Those injured during year had similar LESS scores to those uninjured.

Modified Star Excursion Balance Test

Anterior Reach of the mSEBTWillis, et al. Under Review.

Modified Star Excursion Balance TestPosteromedial Reach of the mSEBTWillis, et al. Under Review.

Modified Star Excursion Balance TestPosterolateral Reach of the mSEBT

Willis, et al. Under Review.

Modified Star Excursion Balance Test4 cm or more difference in anterior reach distance between limbs at 2.5 higher risk of suffering lower leg injuries in high school basketball playersFemales who demonstrated less than 94% composite reach distance were 6.5 times more likely to sustain a lower extremity injury.

Plisky, J Orthop Sports Phys Ther. 2006.

Using Xbox Kinect To Detect Neuromuscular Deficits in Athletes

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Comparison of Motion Sensors for Screening Female Athletes for ACL RiskVicon High cost ~$150,000Lab basedMarker basedPotential errors on marker placement or movementRequires post data collection calculation of anglesLabor intensive setup for each subject KinectLow cost ~$100PortableMarkerlessNo human error

Instant measurement of angles

Minimal setup for each subject

Kinect & KASR3D lower extremity angles difficult to calculate without accurate hip measurementKnee to Ankle Separation Ratio (KASR) is a reliable surrogate for dynamic knee valgus measurementsSteffen, et al. IOC World Conference on Prevention of Injury & Illness in Sport, Monaco 2014.Mizner, et al. CJSM, 2012.

Knee to Ankle Separation RatioDistance between knees/Distance between ankles

Pilot Study: Mass screening in youth athletes for high risk landing patterns Hypothesis: Screening will be safe, efficient, and will identify known gender disparities Population: 180 healthy high school athletesAges 14-18 (Mean age: 16.9 1.31)80 males, 100 femalesBMI: 22.8 3.7

MethodsEach subject performed three successful drop vertical jumps (DVJ) 31 cm tall box with feet positioned 35 cm apart

ResultsSafety There were no injuries reported during the screening testing Efficiency Using two motion sensor device stations, it took 3 minutes to screen and test each subject per station

Average KASR at Initial ContactMales: 1.13Females: 0.967

KASR

Health & Medicine

ACL injury screening and prevention CATS meeting 2016