ACL Injuries in Female Athletes

Patrick S. Buckley, MD

Sports Medicine and Orthopaedic Surgery

patrickb@uognj.com

• I have no disclosures

www.UOANJ.com

Outline• Introduction• Epidemiology• Mechanism and Injury Characteristics• Risk Factors Specific to Females• Treatment Implications/Outcomes• Prevention Strategies• Future Goals

ACL Structure and Function• Primary restraint to anterior tibial translation• 2 bundles-anteromedial and posterolateral to control

translation and rotation.

ACL Structure and Function• A proprioceptive structure as 1% of its

volume is occupied by nerve tissue• Surrounded by synovium so it is an

intraarticular and extrasynovial structure

ACL Tears in Female Athletes• 2.3% increase per year for children

between ages 6-18 in USA1

• ~200,000 annual incidence2

– Increasing steadily over 20 year period

• Females > Males

• Discrepancy begins after puberty3

– Female rates increase more

ACL Tears in Females:Character and Mechanism of Injury

• Non-contact ACL injury most common10-12

– Approximately 70% of ACL injuries non-contact

• Mechanism13

– Foot strike with LE at or close to full extension– +/- forceful valgus moment at knee– +/- tibial internal rotation moment

• Deceleration + cutting most common

• Sports that require pivoting, landing, and sudden deceleration (soccer, gymnastics, basketball, handball, field hockey, lacrosse)

ACL Tears in Females:Character and Mechanism of Injury

• Boden et al, 200913

– Video analysis of non-contact ACL injuries– “Safe” vs “Provocative” landing positions– Injured athletes

• Significantly higher hip flexion angles at contact

– Torso posterior, knee must extend• Hamsting not protective in full extension

(upright body posture)• Lateral trunk displacement• Quadriceps dominant when an anterior

translation force is placed on the tibia

ACL Tears in Females:Risk Factors for Injury

• Extrinsic Factors?• Intrinsic Factors?

– Q-angle– BMI– Hyperlaxity– ACL size– Notch width– Posterior tibial slope– Landing mechanics– Neuromusuclar factors– Genetics– Hormonal factors

Extrinsic Risk Factors• Has not been proven in literature

• 15 year surveillance in NCAA, no change in rates of ACL injury for men or females29

• Single study has found higher rates in females, not males, on artificial surfaces30

• Non-sex-specific: shoe/floor interface, weather, bracing 9,30

– More cleats, larger cleats, turf, dry climate, etc

Intrinsic Risk Factors: Q-Angle• Angle formed by a line drawn from the ASIS to

central patella, and line drawn from central patella to tibial tubercle

• Larger in females31

– Supine: 2.7 to 5.8 degrees larger– Standing: 3.4 to 4.9 degrees larger

• Hypothesized to increase lateral force vector via quad and predispose ACL9

• Static Q-angles not predictive of knee valgus or ACL risk10

Intrinsic Risk Factors: Hyperlaxity• Females have increased generalized hyperlaxity

compared to male counterparts14

– Both sagittal (hyperextension) and coronal (V/V)

• After puberty, flexibility decreases in boys, not girls33

– Sit and Reach tests increase in girls, decrease in boys34

– Knee abduction (valgus) increases during female puberty

• Knee flexibility35

– 47 human cadavers, robotic system to test flexibility– Female knees with increased

• Internal rotation laxity• Valgus laxity• Anterior laxity - 1.3mm average, only at 50 degrees of flexion

– Male knees with increased IR and valgus stiffness

Intrinsic Risk Factors: Hyperlaxity• ACL injured females with more knee

recurvatum and increased ability to touch palms to floor14

• Women with generalized joint laxity32

– 2.7 x greater risk of ACL injury

• Laxity not just in the knee– Increased foot laxity36,37

à navicular drop à tibial translation

Intrinsic Risk Factors: ACL Size• Standardized for BW, females have smaller

ACL9

• Female ACLs demonstrated to have:– Less collagen fibrils per unit area38

– Smaller tensile elastic modulus39

– BUT – neither linked to increased ACL tears

• Dienst et al, 200740

– Females with thinner ACL midsubstance– Correlated with notch width size

• Anderson et al, 200141

– Female ACL smaller than men, but no link to NW– Conclusion that tear rate due to multiple intrinsic factors

Intrinsic Risk Factors: Landing Mechanics• Female athletes demonstrate:

– Increased knee valgus angles in landing/cutting– Higher knee extensor moments– Decreased knee flexion angles in landing– Decreased strength in abductors, glute medius– Increased lateral trunk angle

• These factors result in increased anterior shear force vectors and compression force vectors which places the ACL at risk.

Intrinsic Risk Factors: Landing Mechanics

Ireland et al

Intrinsic Risk Factors: Landing Mechanics• Hewett et al, 20058

– Cohort analysis of 205 female athletes’ landing mechanics– Preseason joint angle and moment analysis – 9 ACL injuries

• Significantly different posture, loading• Knee abduction angle 8 degrees > controls• 2.5 x greater abduction moment• 20% higher GRF• Stance time 16% shorter

– Knee abduction moment predicted ACL injury• 72% specificity• 78% sensitivity

Intrinsic Risk Factors: Landing Mechanics• Hewett et al, 2009; landing video analysis53

– Mean lateral trunk angle higher in females than males in ACL injuries

• 9.3 degrees in ACL injured, 14 degrees in controls– CoM displaced to lateral side of knee– Increases lateral compartment axial forces– Increased abduction moment, valgus landing

• Myer et al, 201554

– Knee abduction moment above 25.3Nm associated with 6.8% ACL injury risk vs. 0.4% risk if below value

– ACL injured females• Increased knee abduction moment• Decreased hamstring to quad strength ratio

Intrinsic Risk Factors: Biomechanics• Compared to males, females land

– More erect, More knee valgus, More external rotation

• LE is a kinetic chain that starts in the core57

– Efficient movement, knee stability, energy transfer– Weak gluts à increased valgus landing– Poor hip control à increased knee loading

• Zazulak et al, 200758

– 277 collegiate athletes– Core weakness predicted knee injury

• 90% sensitive, 56% specific for female ACL injury

– Poor core proprioception predicted female knee injury59

Intrinsic Risk Factors: Genetics• Patients with ACL tears ~2x as likely as non-injured to

have a family member w/ ACL60

• Link identified in female twins61

– Familial disposition, mm imbalance, knee stability

• Collagen Genotypes62

– COL5A1 – CC genotype lower in women w/ ACL injury

• Johnson et al, 201563

– Biopsy samples of torn ACLs, 7 female 7 male– ACAN (aggrecan), FMOD (fibromodulin) up in females– WISP2 (WNT protein) down regulated in female ACL tear

Intrinsic Risk Factors: Other• Hormonal

– Menstral cycle impact on ACL injury risk unclear. No modifications recommended at this time based on menstral cycle.

– Estrogen receptors are present on ACL fibroblasts, but literature unclear on effect9

• Believed to negatively effect tensile properties

– Dragoo et al, 201168

• Elite collegiate female athletes• Relaxin > 6.0pg/mL à 4 x ACL tear risk

• Previous Injury• Anatomic factors

• Notch width, posterior tibial slope, knee valgus, subtalar joint motion

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ACL Tears in Females: Treatment Implications

• Lack of strong data supporting techniques specific to female ACL reconstruction

• Risk Factors summarized as : – Playing with “knock knee” position– Decreased hamstring strength– Reduced hip and knee ROM– MULTIFACTORIAL intrinsic risk factors

ACL Tears in Females: Prevention Strategies• Strengthening, proprioception, motion

training, repetition and routine forming

• Strengthening alone is not enough!76

• Many studies have aimed to investigate the practicality and success of various training programs

• Vertical drop jump test is common

• Drop from box, immediate max vertical• Screening usefulness questioned

recently77

ACL Tears in Females: Prevention Strategies• Hewett et al, 199978

– First study to demonstrate neuromuscular training (NMT) reduces ACL injury risk

– Prospective cohort study, HS female athletes– 6 weeks NMT, 3 x week, 60-90min/session– Non-contact ACL risk lower in trained females

• 72% reduction when compared to untrained• None sustained ACL tears

– Components of effective interventions• Plyometrics• Technique training• Training > 1 x week• Duration of training > 6 weeks

ACL Tears in Females: Prevention Strategies• Mykleburst et al, 200381

– Prospective cohort study over 3 seasons– Norwegian female handball players, >850– Intervention occurred in seasons 2 and 3– 29 ACL injuries in first season (control)– 23 ACL injuries in 2nd, 17 injuries in 3rd

– Significant reduction in NC-ACL tears– Elite division athletes w/ training

• Significant reduction in overall ACL injuries• When normalized for exposure, 36% lower risk

– Compliance an issue• High drop out rates

• Lim et al, 200982

– Improved strength and flexibility in female basketball players s/p NMT intervention

ACL Tears in Females: Prevention Strategies• Mandelbaum et al, 200583

– Cohort study, female soccer, 2 seasons– Over 1000 players vs matched controls– Significant decrease in ACL tear incidence per

1000 player-exposers in trained group– Overall, 6 tears in trained, 67 in untrained

• Petersen et al., 200584

– Female German handball athletes– 10 teams vs 10 controls– Balance board, jumps, bounce mat– ACL injury risk 80% lower in trained (trend)

ACL Tears in Females: Prevention Strategies• Hewett et al, 201785

– Targeted NMT (TNMT)• No running, 5 performance levels• Supervised by athletic trainer; generalizable

– TNMT significantly improved• Hip control• Peak trunk flexion

– High risk athletes improved more

• Pollard et al, 201786

– 30 female soccer players; baseline info– 12 week participation in NMT intervention– Improved knee landing mechanics, trunk

flexion, energy absorption at both knee and hip

ACL Tears in Females: Prevention StrategiesAAOS Appropriate Use Criteria91

“Moderate” strength evidence to support use according to AAOS Evidence Based Clinical Guideline Management of Anterior Cruciate Ligament Injuries

ACL Tears in Females: Prevention Strategies• Length of program matters!92

– Padua et al, 2012– One group performed program for 3 mo– One group performed program for 9 mo– Both improved performance, but only

extended duration group retained improvements 3 months s/p stopping program

• Training fades with discontinuation

• Maintenance program important to make part of training!

ACL Tears in Females: Prevention Strategies• Most effective in93,94

– Younger patients– Higher risk athletes– Elite performance athletes

• Components of a valuable program– Dynamic strengthening of LE kinetic chain– Plyometrics, proprioceptive training– Technique training– Multiple times a week

• 10 minutes / 3 x week minimum recommendation

– Preseason implementation– Continued throughout season– Longer duration of intervention– Identify at risk players

FIFA 11: Apply to Other Sports• ACL injury prevention

program initially for soccer players

• 10-15 min warm-up• Core stabilization,

eccentric training of thigh muscles, proprioceptive training, dynamic stabilization and plyometrics.

• Studying Applicability to other sports

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ACL Tears in Females: The Future• Wearable Technology?95

– Decker et al, 2016– Device measures posture and GRF– Improvements; NNT = 92

• Better, longer-term population based studies on the relationship between genetics, hormonal environment and ACL injuries in females

• Medium and long term outcomes with prevention strategies

ACL Injuries in Female Athletes: Summary

• Female athletes are at greater risk for ACL injury• Risk factors are multifactorial• Prevention strategies can identify high risk

athletes and help to reduce ACL injury risk• Future studies will help guide better prevention

and treatment programs

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Thank you

• Questions?

• patrickb@uognj.com

www.UOANJ.com

References•

– Beck et al. ACL tears in school aged children and adolescents over 20. Pediatrics. 2017; 139(3)– Mather RC et al. Societal and economic impact of anterior cruciate ligament tears. J Bone Joint Surg Am. 2013.– Ford et al. Longitudinal sex differences during landing in knee abduction in young athletes. Med Sci Sports Exerc. 2010; 42(10): 1923-1931– Toth AP, Cordasco FA. Anterior cruciate ligament injuries in the female athlete. J Gend Specif Med. 2001;4(4):25-34– Snaebjornsson T et al. Adolescents and female patients are at increased risk for contralateral angterior cruciate ligament reconstruction: a cohort study from the Swedish National Knee

Ligament Register based on 17,682 patients. Knee Surg Sports Traumatol Arthrosc. 2017– Arendr E,Dick R. Knee injury patterns among men and women in collegiate basketball and soccer: NCAA data and review of the literature. Am J Sports Med. 1995; 23(6):694-701– Prodromos CC, et al. A meta-analysis of the incidence of anterior cruciate ligament tears as a function of gender, sport, and knee injury-reduction regimen. Arthroscopy. 2007; 23(12):

1320-1325– Hewett et al. Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes. A prospective study. Am J

Sports Med. 2005; 33(4): 492-501– Giugliano DN et al. ACL tears in female athletes. Phys Med Rehabil Clin N Am. 2007; 18(3): 417-438– Hewett et al. Anterior cruciate ligament injuries in female athletes: Part 1. Mechanisms and risk factors. Am J Sports Med. 2006; 34(2): 299-311.– McNair et al. Important features associated with acute anterior cruciate ligament injury. N Z Med J. 1990; 103: 537-539– Boden et al. Mechanisms of anterior cruciate ligament injury. Orthopaedics. 2000; 23: 573-578– Boden et al. Video analysis of anterior cruciate ligament injury: abnormalities in hip and ankle kinematics. Am J Sports Med. 2009; 37(2): 252-259– Boden et al. Noncontact anterior cruciate ligament injuries: mechanism and risk factors. JAAOS. 2010; 18: 520-527– Renstrom P et al. Non-contact ACL injuries in female athletes: an International Olympic Committee current concepts statement. Br J Sports Med. 2008; 42(6): 394-412– Pandy MG and Shelburne KB. Dependence of cruciate-ligament loading on muscle forces and external load. J Biomech. 1998; 30(10):1015-1024– Simosen EB et al. Can the hamstring muscles protect the anterior cruciate ligament during a side-cutting maneuver? Scand J Med Sci Sports. 2000;10(2)):78-84– DeMorat et al. Aggressive quadriceps loading can induce noncontact anterior cruciate ligament injury. Am J Sports Med. 2004; 32(2): 477-483– Van Eijden et al. The orientation of the distal part of the quadriceps femoris muscle as a function of the knee flexion-extension angle. J Biomech 1985; 18(10):803-809– Nisell et al. Mechanics of the knee: a study of joint and muscle loads with clinical applications. Acta Orthop Scand Suppl. 1985;216: 1-42– Torzilli et al. The effect of joint-compressive load and quadriceps muscle force on knee motion in the intact and anterior cruciate ligament-sectioned knee. Am J Sports Med. 1994; 22(1):

105-122– Myer et al. Tibiofemoral contact pressures and osteochondral microtrauma during anterior cruciate ligament rupture due to excessive compressive loading and internal torque of the

human knee. Am J Sports Med. 2008;36(10):1966-1977– Meyer et al. Osteochondral microdramage from valgus bending of the human knee. Clin Biomech. 2009; 24(7): 577-582– Dejour et al. Tibial translation after anterior cruciate ligament rupture: two radiological tests compared. J Bone Joint Surg Br– Griffin et al. Importance of the tibial slope for stability of the posterior cruciate ligament deficient knee. Am J Sports Med. 2007; 35(9): 1443-1449

References– McNitt-Gray et al. Kinetics of the lower extremities during drop landings from three heights. J Biomech 1993; 26(9): 1037-1046– Borden et al. Tibiofemoral alignment: contributing factors to noncontact anterior cruciate ligament injury. J Bone Joint Surg Am. 2009; 91(10):2381-2389– Hashemi et al. The geometry of the tibial plateau and its influence on the biomechanics of the tibiofemoral joint. J Bone Joint Surg Am. 2008; 90(12): 2724-2734– Mihata et al. Comparing the incidence of anterior cruciate ligament injuries in collegiate lacrosse, soccer, and basketball players: Implications for anterior cruciate ligament mechanism

and prevention. Am J Sports Med. 2006; 34(6): 899-904– Olsen et al. Relationship between floor type and risk of ACL injury in team handball. Scand J Med Sci Sports. 2003; 13(5): 299-304– Conley et al. The female knee: Anatomic variations. J Am Acad Orthop Surg. 2007; 15(S1): S31- S36– Uhorchak et al. Risk factors associated with noncontact injury of the anterior cruciate ligament: a prospective four-year evaluation of 859 West Point cadets. Am J Sports Med. 2003;

31(6): 831-842– Beunen GP et al. Physical activity and growth, maturation, and performance: a longitudinal study. Med Sci Sports Exerc. 1992– Malina RM et al. Timing and sequence of changes in growth, maturation, and performance during adolescence. In : Growth, Maturation, and Physical Activity. Champaign, IL. Human

Kinetics; 1991– Boguszewski DV et al. Male-Female differences in knee laxity and stiffness. Am J Sports Med. 2015; 43(12)– Loudon JK et al. The relationship between static posture and the ACL in female athletes. J Orthop Sports Phys Ther. 1996– Trimble MH et al.The relationship between clinical measurements of lower extremity posture and tibial translation. Clin Biomech. 2002: 17: 286-290– Hashemi J et al. The human anterior cruciate ligament: sex differences in ultra-structure and correlation with biomechanical properties. J Orthop Res. 2008; 26(7): 945-950– Handrashekar N et al. Sex-based differences in the tensile properties of the human anterior cruciate ligament. J Biomech, 2006; 39(16): 2943-2950– Dienst et al. Correlation of intercondylar notch cross sections to the ACL size: a high resolution MR tomographic in vivo analysis. Arch Orthop Trauma Surg. 2007; 127 (4): 253-260– Anderson et al. Correlation of anthropometric measurements, strength, anterior cruciate ligament size, and intercondylar notch characteristics to sex differences in anterior cruciate

ligament tear rates. Am J Sports Med. 2001; 29(1): 58-66– LaPrade RF et al. Femoral intercondylar notch stenosis and correlation to Anterior cruciate ligament injuries: A prospective study. Am J Sports Med. 1994; 21(4): 535-539.– Ireland et al. A radiographic analysis of the relationship between the size and shape of the intercondylar notch and anterior cruciate ligament injury. Knee Surg Sports Traumatol

Arthosc. 2001; 9(4): 200-205– Sturnick et al. Combined anatomic factors predicting risk of anterior cruciate ligament injury for males and females. Am J Sports Med. 2015; 43(4)– Brandon et al. The association between posterior-inferior tibial slope and anterior cruciate ligament insufficiency. Arthroscopy. 2006;22(8): 894-899– Todd et al. The relationship between posterior tibial slope and anterior cruciate ligament injuries. Am J Sports Med. 2010; 38(1): 63-67– Hohmann et al. Is there a correlation between posterior tibial slope and non-contact anterior cruciate ligament injuries? Knee Surg Sports Traumatol Arthorsc. 2011; 19(S1): S109-S114– Hashemi et al. Shallow medial tibial plateau and steep medial and lateral tibial slopes: new risk factors for anterior cruciate ligament injuries. Am J Sports Med. 2010; 38(1): 54-62– Terauchi et al. Sagittal alignment of the knee and its relationship to noncontact anterior cruciate ligament injuries. Am J Sports Med. 2011; 39(5): 1090 -1094– Beynnon BD et al. Increased slope of the lateral tibial plateau subchonral bone is associated with greater risk of noncontact ACL injury in females but not in males: a prospective cohort

study with a nested, matched case-control analysis. Am J Sports Med. 2014; 42(5)

References– Lipps et al. Morphologic characteristics help explain the gender difference in peak anterior cruciate ligament strain during a simulated pivot landing. Am J Sports Med. 2012; 40(1): 32-40– Wang YL et al. Association between tibial plateau slopes and anterior cruciate ligament injury: a meta-analysis. Arthroscopy 2017; 33(6): 1248-1259– Hewett et al. Video analysis of trunk and knee motion during non-contact anterior cruciate ligament injury in female athletes: lateral trunk and knee abduction motion are combined

components of the injury mechanism. Br J Sports Med. 2009; 43(6):417-422– Myer et al. High knee abduction moments are common risk factors for patellofemoral pain and anterior cruciate ligament injury in girls: Is PFP itself a predictor for subsequent ACL injury?

Br J Sports Med. 2015; 49(2): 118-122.– Leppanen M et al. Stiff landings are associated with increased ACL injury risk in young female basketball and floorball players. Am J Sports Med. 2016; 45(2)– Numata et al. Two-dimensional motional analysis of dynamic knee valgus indentifies female high school athletes at risk of non-contact anterior cruciate ligament injury. Knee Surg Sports

Traumatol Arthrosc. 2017– Ford KR et al. Longitudinal effects of maturation on lower extremity joint stiffness in adolescent athletes. Am J Sports Med. 2010; 38(9): 1829-1837– Zazulak et al. Deficits in neuromuscular control of the trunk predict knee injury risk. A prospective biomechanical-epidemiologic study. Am J Sports Med. 2007; 35(7): 1123-1130– Zazulak et al. The effects of core proprioception on knee injury: A prospective biomechanical-epidemiological study. Am J Sports Med. 2007. 35(3): 368-373– Flynn et al. The familial predisposition toward tearing the anterior cruciate ligament: a case control study. Am J Sports Med. 2005;33(1):23-28– Hewett et al. Multiple risk factors related to familial predisposition to anterior cruciate ligament injury: fraternal twin sisters with anterior cruciate ligament ruptures. Br J Sports Med.

2010; 44(12): 848-855– Posthumus M et al. The COL5A1 gene is associated with increased risk of anterior cruciate ligament ruptures in female participants. AM J Sports Med. 2009; 37(11): 2234-2240– Johnson JS et al. Gene expression differences between ruptured anterior cruciate ligaments in young male and female subjects. J Bone Joint Surg Am. 2015; 97(1): 71-79– Yu et al. Combined effects of estrogen and progesterone on the anterior cruciate ligament. Clin Orthop Relat Res. 2001; 383: 268-281– Lebrun CM. The effect of the phase of the menstrual cycle and the birth control pill in athletic performance. Clin Sports Med. 1994; 13: 419-441– Faryniarz et al. Quantification of estrogen receptors and relaxin binding in human anterior cruciate ligament fibroblasts. In Vitro Cell Dev Biol Anim. 2006; 42: 176-181– Konopka JA et al. The intracellular effect of relaxin on female anterior cruciate ligament cells. Am J Sports Med. 2016; 44(9)– Dragoo et al. Prospective correlation between serum relaxin concentration and anterior cruciate ligament tears among elite collegiate female athletes. Am J Sports Med. 2011: 39: 2175-

2780– Nose-Ogura S et al. Oral contraceptive therapy reduces serum relaxin-2 in elite female athletes. J Obstet Gynaecol Res. 2017;43(3): 530-535– Herzberg et al. The effect of menstrual cycle and contraceptives on ACL injuries and laxity: A systematic review and meta-analysis. OJSM. 2017:5(7)– Zazulak et al. The effects of the menstrual cycle on anterior knee laxity: a systematic review. Sports Med. 2006; 36(10): 847-862– Beynnon et al. The relationship between menstrual cycle phase and anterior cruciate ligament injury: A case control study of recreational alpine skiers. Am J Sports Med. 2006; 34(5): 757-

764– Van eck CF et al. Femoral intercondylar notch shape and dimensions in ACL-injured patients. Knee Surg Sports Traumatol Arthosc. 2010; 18(9): 1257-1262– Ageberg et al. Sex differences in patient reported outcomes after anterior cruciate ligament reconstruction: Data from the Swedish knee ligament register. Am J Sports Med. 2010;

38(7):1334-1342– Shelbourne KD et al. Incidence of subsequent injury to either knee within 5 years after anterior cruciate ligament reconstruction with patellar tendon autograft. Am J Sports Md.

2009;37(2): 246-251

References– Herman et al. The effects of strength training on the lower extremity biomechanics of female recreational athletes during a step drop jump task. Am J Sports Med. 2008; 34(4): 733-40– Krosshaug T et al. The vertical drop jump is a poor screening test for ACL injuries in female elite soccer and handball players: a prospective cohort study of 710 athletes. Am J Sports Med.

2016; 44(4)– Hewett et al. The effect of neuromuscular training on the incidence of knee injury in female athletes: a prospective study. Am J Sports Med. 1999; 27: 699-706

•– Heidt et al. Avoidance of soccer injuries with preseason conditioning. Am J Sports Med. 2000; 28; 659-662– Soderman et al. Balance board training: prevention of traumatic injuries of the lower extremities in female soccer players? A prospective randomized intervention study. Knee Surg Sports

Traumatol Arthroc. 2000; 8:356-363– Mykleburst et al. Prevention of anterior cruciate ligament injuries in female team handball players: a prospective intervention study over three seasons. Clin J Sports Med. 2003; 13:71-78– Lim BO et al. Effects of sports injury prevention training on biomechanical risk factors of anterior cruciate ligament injury in high school female basketball players. Am J Sports Med. 2009.

37(9)– Mandelbaum et al. Effectiveness of a neuromuscular and proprioceptive training program in preventing anterior cruciate ligament injuries in female athletes: two-year followup. Am J

Sports Med. 2005; 33;1003-1010– Petersen et al. A controlled prospective case control study of a prevention training program in female team handball players: the German experience. Arch Orthop Trauma Surg. 2005– Hewett et al. Effectiveness of neuromuscular training based on the neuromuscular risk profile. Am J Sports Med. 2017– Pollard CD et al. ACL injury prevention training results in modification of hip and knee mechanics during a drop-landing task. OJSM. 2017; 5(9)– Noyes FR and Westin SD. Anterior cruciate ligament injury prevention training in female athletes: a systematic review of injury reduction and results of athletic performance tests. Sports

Health. 2012.– Stevenson JH et al. Assessing the effectiveness of neuromuscular training programs in reducing the incidence of anterior cruciate ligament injuries in female athletes: a systematic review.

Am J Sports Med. 2014; 43(2)– Hewett et al. Anterior cruciate ligament injuries in female athletes: part 2, a meta-analysis of neuromuscular interventions aimed at injury prevention. Am J Sports Med. 2006; 34(3)– Sadoghi et al. Effectiveness of anterior cruciate ligament injury prevention training programs. J Bone Joint Surg Am. 2012; 94(9):769-776– American Academy of Orthopaedic Surgeons: Management of Anterior Cruciate Ligament Injuries Evidence-Based Clinical Practice Guideline. Rosemont, IL, American Academy of

Orthopaedic Surgerons, 2014. http://www.aaos.org/research/guidelines/ACLGuidelinesFINAL.pdf– Padua et al. Retention of movement pattern changes after a lower extremity injury prevention program is affected by program duration. Am J Sports Med. 2012; 40(2): 300-306– Myer et al. The influence of age on the effectiveness of neuromuscular training to reduce anterior cruciate ligament injury in female athletes: a meta-analysis. Am J Sports Med. 2013;

41(1): 203-215– Myer et al. The influence of age on the effectiveness of neuromuscular training to reduce anterior cruciate ligament injury in female athletes: a meta-analysis. Am J Sports Med. 2013;

41(1): 203-215– Decker MJ et al. A wearable neuromuscular device reduces ACL injury risk in female soccer athletes. OJSM. 2016; 4(7) – Hudek et al. Is non-contact ACL injury associated with the posterior tibial and meniscal slope? Clin Orthop Relat Res. 2011: 469(8): 2377-2384.

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