ACL Injury: What are the Risk Factors? Kenneth G. Swan, Jr., M.D. June 2, 2015

Transcription

1 ACL Injury: What are the Risk Factors? Kenneth G. Swan, Jr., M.D. June 2, 2015

2 I have no disclosures

3 ACL injuries (ACLIs) are 3-6x more common in females than males But there s more to it than that. What does the Evidence say about ACL injury Risk Factors?

4 ACL Injury Risk Factors? Non-modifiable Genetics Female Gender Notch width Posterior tibial slope ACL size Ligamentous laxity Modifiable High BMI Jump landing mechanics Hormonal Playing surface

5 Non-modifiable Risk Factors

6 ACLI and Genetics Many anecdotal reports of ACL injuries running in families Two case-control studies support this theory Harner, AJSM 1994; Flynn, AJSM 2005 However, overall Evidence is poor, level III at best Genetic studies exist, but few Cannot make definitive conclusions or practice recommendations.yet

7 Does the size of the intercondylar notch effect the risk of ACLI?

8 ACL Injury Risk Factors: Intercondylar Notch Width Notch Width Index (NWI) = width of intercondylar notch/width of distal femur at level of popliteal groove as seen on tunnel view radiographs Souryal, AJSM, 1988

9 Notch Width Several* prospective level II evidence cohort studies have shown: a) Females have smaller NWIs than males b) Male and female athletes with ACLIs have significantly more notch stenosis than athletes without ACLIs *Souryal, AJSM, 1993; LaPrade, AJSM, 1994; Uhorchak, AJSM, Zeng, Knee Surg Sports Traumatol Arthrosc, 2013 Meta-analysis (III)

10 Does the geometry of the tibial slope play a role in ACLI?

11 Bony geometry of tibial plateau and ACLI Both the concavity depth of the medial plateau and the degree of posterior-inferior tibial slope have been studied Studies suggest that increased posterior tibial slope places athletes at higher risk for noncontact ACLIs

12 Posterior Tibial Slope: What s the Evidence? Best evidence implicating increased posterior tibial slope as a risk factor for ACLIs is LEVEL III Radiograph-based, case control studies A recent Level III study suggests it is a combination of increased posterior slope and tight intercondylar notch that places female athletes at risk* Stijak, Knee Surg Sports Traumatol Arthrosc 2008; Simon, J Biomech 2010; Todd, AJSM 2010; Hashemi, AJSM 2010 *Sturnick, AJSM 2015

13 ACL size: Does size matter? Females suffer higher rates of ACL injuries than men ACL in females is smaller than male counterparts Chandrashekar, AJSM 2005 Smaller ACL (MRI) found in c/l knee of ACLI patients vs controls Chaudhari, AJSM 2009 Smaller ACL (U/S) diameter is a predictor of ACL injury Mahajan, BioMed Research Int l 2015 Evidence: poor, few studies, two Level III

14 Ligamentous Laxity Is generalized or focal pre-injury laxity a risk factor for ACLI?

15 Ligamentous Laxity Generalized ligamentous laxity, as measured by 5 th MCP hyperextension, thumb-to-forearm test, and elbow hyperextension has been suggested as a RF for ACL tear. Healthy females have greater ligamentous laxity about the knee and ankle compared to males (Beynnon, AJSM 2005 Level II) Knee laxity alone (passive hyperextension or via KT- 1000) or as part of systemic laxity, has also been associated with ACLI in several studies

16 Ligamentous Laxity and ACLI: What s the Evidence? Level of Evidence II Uhorchak, AJSM, 2003 Prospective cohort of 859 West Point cadets followed over 4 years Male RFs: small notch and generalized laxity Female RFs: small notch, generalized laxity, and high BMI and KT-2000 Vauhnik, KSSTA 2008 Prospective cohort of Slovenian female athletes Passive knee hyperextension and anterior laxity preseason a significant RF for ACL injury

17 Non-modifiable Risk Factors Genetics/Family history Female Gender Small Notch size Increased posterior tibial slope Small ACL size Ligamentous laxity

18 Non-modifiable Risk Factors Genetics/Family history Female Gender Small Notch size Increased posterior tibial slope Small ACL size Ligamentous laxity

19 ACL Injury: Modifiable Risk Factors

20 Does BMI play a role in ACLI? Higher than avg. BMI found to significantly increase risk of ACL injury in female (but not male) military cadets Uhorchak, AJSM 2003 Single study, level II

21 Neuromuscular Control Several studies have implicated female jump landing and pivoting techniques as different than males and a risk factor for ACL injury Basis for several successful ACL prevention programs PEP, SportsMetrics Hewett, AJSM 1999, 2005 Prospective cohort studies, level II Adolescent females who participated in a pre-season plyometrics program had lower rates of ACL injuries Adolescent female basketball players who jump land with increased knee abduction (valgus knee) had higher rate of ACL injuries

22 At Risk Jump-Landing technique

23 Jump Landing Technique

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25 Do hormonal factors play a role in ACLI? Higher incidence of ACLI in females this difference is not seen until ~puberty Ligamentous laxity Relaxin Hormone receptors found on ACL Highest incidence of ALCI during follicular, preovulatory phase? What about oral contraceptives?

26 Ovarian Cycle

27 Hormones and ACLI: The Evidence Very little evidence Conflicting data from level III and IV studies OCPs have not been proven to have a protective or deleterious effect on the ACL..

28 Extrinsic Risk Factors Cleat type Higher torsion, higher risk Weather conditions Hot, dry worse than moist Field surface Bermuda grass>> Rye grass FieldTurf >> Grass Hershman, AJSM % higher risk of ACL injury on FieldTurf!

29 Extrinsic Factors: What s the Evidence Too few studies to make conclusions regarding cleat type, field condition and turf type

30 Summary: What does the evidence say about ACL injury risk factors?

31 ACL Injury Risk Factors? Modifiable High BMI Jump landing mechanics Hormonal? Playing surface? Non-modifiable Female Gender Genetics? Notch width ACL size? Tibial slope? Ligamentous laxity

32 Screeing programs designed to identify those athletes who will best benefit from ACL prevention programs are desirable Those [female] athletes with a prior ACL injury, poor jump landing mechanics, ligamentous laxity, and perhaps a family history are good candidates for such a program Identifying those with anatomic risk factors (small ACL and tight intercondylar notch) may be in our future

33 Screeing programs designed to identify those athletes who will best benefit from ACL prevention programs are desirable RECOMMENDATION: Those [female] athletes with a prior ACL injury, poor jump landing mechanics, ligamentous laxity, and perhaps a family history are good candidates for such a program Identifying those with anatomic risk factors (small ACL and tight intercondylar notch) may be in our future

34 Evidence Based References (Level II or higher)

35 Modifiable Risk Factors Hewett TE, Lindenfeld TN, Riccobene JV, 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(6): Hewett TE, Myer GD, Ford KR et al. Biomechanical measures of neuromuscular control of valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: A prospective study. Am J Sports Med 2005;33(4):

36 Non-modifiable risk factors LaPrade RF, Burnett QM. Femoral intercondylar notch stenosis and correlation to anterior cruciate ligament injuries. Am J Sports Med 1994;22: Souryal TO, Freeman TR. Intercondylar notch size and anterior cruciate ligament injuries in athletes. Am J Sports Med 1993;21: Uhorchak JM, Scoville CR, Williams GN et al. Risk factors associated with noncontact injury of the anterior cruciate ligament: a prospective fouryear evaluation of 859 West Point cadets. Am J Sports Med 2003;31: Vahunik R, Morrissey MC, Rutherford OM, et al. Knee anterior laxity: A risk factor for traumatic knee injury among sportswomen? Knee Surg Sports Traumatol Arthrosc 2010;19(3):

37 THANK YOU