BASKETBALL ACL Injury Rate,

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1 Elizabeth A. Arendt, M.D. University of Minnesota Professor and Vice Chair Past Medical Director of Intercollegiate Athletics BASKETBALL ACL Injury Rate, Agel, Arendt, et al., AJSM, 2005 Agel, Arendt, et al., AJSM, 2005 SOCCER ACL Injury Rate, No significant change in rate of ACL injury in men or women over a 15 yr period 0.13 Agel, Arendt, et al., AJSM, 2005 Mihata LC et al., AJSM 2006 Page 1 of 8

2 Page 2 of 8 Hunt Valley Consensus Conference June 1999 Hunt Valley Consensus Conference February 2005 International Olympic Committee Current Concepts Statement Lausanne Feb An Update on ACL Injury Risk & Prevention (Retreat #5) Greensboro March 2010 BJSM, June 2008 J. Athletic Training 45: , 2010 Estrogen / progesterone most obvious / most studied hormonal Relaxin Powerful ligament relaxer Testosterone are we missing a potential protective effect?? Material Property level : ligaments / tendons Neuromuscular level : central or peripheral Cellular level : ligament structure /composition collagen / proteoglycans Model: primate 26 animals (26 ACL/26 PT) 2 years ligament failure test If there is a hormonal effect on knee function it is unlikely at the ligament material properties level No correlation between ACL or Patellar tendon material properties and estrogen levels Arendt et al., AJSM, 2006 How else could hormones have an effect?? Neuromuscular mechanism?

3 Page 3 of 8 3,150 athletes participated 2 basketball seasons, 1 soccer season 209 schools no OCP (64%) / used OCP (36%) RESULTS: No difference in the rate of non-contact ACL or ankle sprain injury based on use of oral contraceptives Arendt et al., Med. Science & Sport, 2006 A meta-analysis (9 studies) Anterior knee laxity was greater in the ovulatory phase than the luteal phase and least in the follicular phase More injuries in the follicular phase. Inadequate data exists to make any conclusive statement regarding the effects of the menstrual cycle on knee laxity and on ACL injury rates. Zazulak BT, Hewett TE, et al.: Sports Med 2006 Menstrual cycle phase & ACL Injury Inconclusive data Published studies to date support an increase in NC-ACL injuries in the pre-ovulatory phase! No reasonable theories as to mechanism! Examine the interaction among hormones, mechanical loading, neuromuscular response, & ACL mechanical properties in the physically active (fe)male Examine ACL injury in genome-wide association studies to establish possible genetic components to ACL injury. et.al., R. Kevin Flynn, Alexandra Kirkley, Am. J. Sports Med Conclusion: The COL12A1 AluI RFLP in exon 65 is associated with ACL ruptures in females. The results suggest that females with an AA genotype are at a 2.4 times increased risk of ACL ruptures. Vicki L. Wilke, DVM, PhD, DACVS Martin et al. Posthumus M, van der Merwe W, P Schwellnus, Malcolm Collins, Br. J. Sports Med. May 2009

4 Page 4 of 8 Incidence 20% of cases seen at veterinary teaching hospitals for lameness Surgery recommended in dogs >35 # 50% have bilateral CCLR Higher genomic similarity with human Dogs experience similar, spontaneously occurring diseases as humans Similar physiology Breeds : partially inbred, genetic isolates Cost: ~$1-4,000/ knee Kirkness et al. Science 2003 Identification of genetic mutation(s) that cause or predispose individuals to disease genetic counseling Identification of environmental factors that influence genetic expression of disease (phenotype) smoking, body weight, exercises Identification of genetic intervention to prevent progression of disease to end-stage Females more typically had the posterolateral tibial bony contusion pattern compared to males Females have a lower incidence of full-thickness articular lesions in ACL-injured knees. Fayad LM et al. Skeletal radiology 2003 Rotterud JH et al., AJSM 2011 Control Limb Rotation under Pelvis Land with a flexed knee and hip Plant / Pivot with knee and foot within vertical cylinder of upper body Heidt 2000 Olsen 2005 Johnson 1995 Mandelbaum 1995 Henning 1990 Hewett 1999 BOLD decreased knee injury risk Underline decrease ACL injury risk * No effect in injury risk Mandelbaum 2005 Mykelbust 2003 Caraffa 1996 *Pfeiffer 2004 *Soderman 2000 *Wedderkopp 2003

5 Page 5 of 8 Alter dynamic loading of the knee joint through neuromuscular and proprioceptive training (eg) Knee over toe position / avoid at risk positions and Recommended elements : Strength / power exercises, neuromuscular training, plyometrics &agility exercises, warm-up. Although results are promising, ACL injury rates & the sex disparity have not yet diminished. The ideal prevention program has yet to be identified The protective effects of ACL injury-prevention training programs appear to be transient. Field assessment and screening tools show promise for identifying at risk individuals. Best age to target screening not yet identified. ACL injury mechanisms / prospective risk factors --- the same in pediatric and adult populations? the use of the drop vertical jump (DVJ) test to assess the risk of ACL injury in female athletes (pkneeadmom) N =1855 over 3 yrs. HS/ college level 20 (+) ACL matched to 45 uninjured RESULTS: no association pkam & NC-ACL Goetschius J, et.al., JSM 2013 Which biomechanical / neuromuscular profiles (trunk, core, hip) cause noncontact ACL rupture? An understanding of the causes is central to identifying how to screen at risk individuals Is gross failure of the ACL caused by a single episode or multiple episodes? Are ACL injuries governed by a single or multiple neuromuscular / biomechanical profile(s)? Mixed conclusions if SEX is a risk factor Re-injury of initial ACL Injury to contra-lateral knee

6 Page 6 of 8 Femoral notch width is a good predictor of ACL size (area and volume) in M but not F Femoral notch angle is a good predictor of ACL size in F but not in M. Compared with ACL uninjured people, injured individuals have smaller ACLs Chandrashekar N et al., AJSM 2005 Chaudhari AM et al., AJSM 2009 Both condyles have a 7-10 degree posterior inclination with respect to the shaft of the tibia (tibial slope) Compliments of Charlie Brown, M.D. The lateral condyle is flat or convex The medial condyle is concave The lateral condyle has a smaller radius of curvature posteriorly than the medial condyle Compliments of Charlie Brown, M.D. Compliments of Charlie Brown, M.D. There is a 6 mm increase in anterior tibial translation for every 10 degree increase in anterior tibial slope H. DeJour and Bonnin, JBJS, 1994 Lazar et al., Knee Surg, Sp Trauma, Arthros Nov 2007 Measured MRI geometry of lateral joint Ho: ACL Injured athlete has more highly convex joint surfaces. N = 173 : NC-ACL athletes age & activity matched to non-injured athletes RESULTS: all Females / + ACL males shorter tibial plateau length (femur) femur more convex articulating surfaces Wahl,et.al., JBJS 2012 Cadaver study: N = 20 Ht. & Wt. matched M/F knees Simulated pivot / landing RESULTS: ACL x-sectional area & lateral tibial slope were significant predictors of peak AM-ACL strain (R2 =.59; P =.001). Lipps D, et.al., AJSM 2012

7 Page 7 of 8 Patients with a contralateral ACL injury demonstrated significantly tibial IR, ER compared to healthy volunteers. Females demonstrated internal & external rotation, as well as rotational compliance compared with males (p< 0.001) Branch T, Arendt E, et al., KSST, 2009 Prospective 4 yr.cohort study, West Point cadets (n=859) Recorded multiple P.E. / Xray variables Results Incidence of NC-ACL injury in class of % in males 6.8 % in females Uhorchak et al., AJSM, 2003 Patellar tendon - inclination angle & posterior tibial slope are independent risk factors for ACL injury. Uhorchak et al., AJSM, 2003 Examining radiographs may offer a simple tool for estimating ACL injury risk for an individual athlete. Brown G, Arendt E, et al., poster AOSSM annual meeting 2012 Lateral Tibial Posterior Slope and Early Graft Failure Following ACL Reconstruction J. Christensen, MD, et.al. Case-control format Skeletally mature Matched cohort Early ACL graft failure (<2 years from primary surgery) vs Intact ACL grafts at minimum 4 year follow-up Age (± 5 years) Gender Date of primary surgery (± 5 years) Graft type BTB autograft Hamstring autograft Allograft 2 MFME slide Mean time to graft rupture in early failure group one year ( years) Mean follow-up of the matched control group 6.9 years ( years) with no evidence of graft rupture Tibial rotation Anatomic alignment (genu varum) Size and Convexity of Tibial slope HIGH RISK of ACL INJURY

8 Page 8 of 8 Reductionist View : Breakdown into Parts Hormones Laxity Q-angle Notch Width NM Strategies Prior Injury ACL Injury The sum of the parts equal the whole Assumes each part contributes equally Random mixing of parts are ignored Quatman & Hewett, BJSM, 2009 Less Reductionist View Hormones Laxity Q-angle Notch Width NM Strategies Prior Injury Feedback loops, interrelations and weighting of relationships ACL Injury Can not reduce parts and retain meaning of the whole Assumes parts are not equal Assumes nonrandom mixing is important Quatman & Hewett, BJSM, 2009 Neuromuscular Factors Anatomic Factors Laxity Factors Hormonal Factors?Sex? Women should be more like men Sports Medicine Institute University of Minnesota