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ACL prevention rev

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Female ACL injuries can be prevented by strengthening /balancing muscles.

Female ACL injuries can be prevented by strengthening /balancing muscles.

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  • When knee joint is placed under a shear load, load-sharing between the ligaments and muscles crossing the knee is GENERALLY in proportion to the relative stiffness that develops in the direction of loading.
  • 24 NCAA Athletes (12 men, 12 women) compared w/28 collegiate endurance (14 men, 14 women). (High Risk: B-ball, V-ball, Soccer) (Low Risk: Bicycling, Crew, Running) Matched for age, height, weight, Body Mass Index, shoe size and activity level. Tested on seated weighted pendulum that applied medially directed force to lateral aspect of leg. Internal Rotation measured optically to nearest .25 o at 30 and 60 deg knee flexion both w/and without maximal activation of knee muscles. Conclusion: Maximal rotations of the leg in women than in men in both the passive and active muscle state (16% and 27% greater respectively) Additionally, overall torsional stiffness on the knee between genders showed a 42% difference. Effects of knee flexion: Tibial rotation significantly decreased as knee flexion increased from 30 – 60 deg in both passive and active muscle state.
  • Eccentric quadriceps forces on anterior tibia have been demonstrated to reach 500N when knee is flexed 10-20 deg (relatively extended position).
  • Muscle activity that occurs following perturbation or stimulus is termed Reactive Muscle Activity (RMD)l
  • If loads become too great for the body to accommodate or if impact absorption fails, an injury will occur.
  • Malinzak et al presented the following data American Orthopaedic Society for Sports Medicine Specialty Day, 1999.
  • Both proprioceptive and hamstring exercises have shown considerable
  • Both proprioceptive and hamstring exercises have shown considerable
  • Transcript

    • 1. ACL Injuries in the Female Athlete Prevention Strategies • 8th Annual Force Health Protection Conference • 9 August 2005
    • 2. Daniel I Rhon, MPT CPT, United States Army Medical Specialist Corps Physical Therapist William Beaumont Army Medical Center
    • 3. Anterior Cruciate Ligament • One of two internal stabilizers • Crucial ligament for the competitive athlete
    • 4. ACL ANATOMY • Necessary for athletes involved in cutting and jumping sports
    • 5. ACL ANATOMY • Strong ligament – essential for knee stability
    • 6. Tears Common In Contact Sports
    • 7. Incidence of ACL Injuries • Annually ~ 200,000 ACL tears occur in the US • Non-contact ACL injuries occur most commonly in both males & females
    • 8. Noyes et al. • The Cincinnati Sports Medicine Group reported that 78% of ACL injuries result from non-contact mechanisms, most commonly landing from a jump, cutting, or sudden deceleration
    • 9. ACL Deficiency – Often associated with meniscal cartilage damage – And articular cartilage damage – May not be repairable!
    • 10. Sequelae of Meniscal Damage • Experimentally even partial meniscectomy increases contact pressures (up to 350%)! • Degenerative changes on X-rays much more frequent: 75% vs 5% » Fairbanks, JBJS; 1948: 30B;664-670.
    • 11. ACL Deficiency • Isolated Tear: – Relatively easy to reconstruct – BUT: • Season ender • Patient morbidity • Prolonged rehab • Return to form • Loss to team
    • 12. ACL Tear Risk • Increased incidence in female athletes: – Basketball, volleyball and soccer • 4 times greater than in males!
    • 13. ACL Tear Risk • Incidence in General population: – 0.4/1000 • Incidence in high school female athletes: – 1/100 • Incidence in college female athletes: – 1/10 • 200-fold increased risk over general population!
    • 14. Proportional Increase of Injury? • Knee injury highest for spring football followed by: – Women’s gymnastics – Women’s soccer – Men’s wrestling – Men’s soccer – Women’s basketball.
    • 15. Increased Rate of ACL Tears in Female Athletes • WHY? – Complex Interactions – Multifactorial • Intrinsic Factors • Extrinsic Factors
    • 16. Impact of Title IX • Title IX Educational Assistance Act of 1972 – Equal representation of scholastic sports for both men and women • Since inception, female participation in athletics has increased from 300,000 TO 2.37 million
    • 17. Financial Setback • 1997 Costs for ACL repair/reconstruction: - $17,000 (treatment & rehab) • Total cost could exceed $646M / annually for HS/College athletes
    • 18. Intrinsic Factors (Not Controllable) • Smaller size or ACL • Greater rotatory laxity • Valgus mal-alignment • Hyperextension • Diminished proprioception • Hormonal influence (estrogen) • Intercondylar notch shape & width (White KK., 2003) (Flynn JM., 2002)
    • 19. Female Anatomic Alignment
    • 20. Physiological Extrinsic Factors (Modifiable) Knee stiffness Activation Patterns Neuromuscular characteristics of dynamic restraints Landing Differences
    • 21. Knee Stiffness • Knee stiffness is an important component in knee joint stability • External loads applied to knee are resisted by passive (ligament) and active (muscle) restraints • Hence, insufficient muscular stiffness posses increased risk for ligamentous damage
    • 22. Knee Stiffness (40 Female Div I athletes, 60 Male football players, 40 controls; male/female) – Women’s knees looser than men’s – Women’s Quad and HS weaker (even when body corrected by height and weight) – Women more dependent on quad to stabilize knees • Interestingly: Female athletes no better than female controls in activating HS to stabilize knee Huston and Wojtys, Am J Sports, 1996
    • 23. Knee Stiffness (cont) • 24 ‘high risk’ athletes compared with 28 ‘low risk’ athlete – Measured knee stiffness using weighted pendulum (both with and w/o mm activation) • CONCLUSION: Collegiate female ‘high risk’ athletes exhibited less muscular protection of knee ligaments than did size and sport-matched male athletes Wojtys et al, 2003
    • 24. Muscle Activation Patterns FEMALE Quadriceps Dominant: - Increases anterior load seen Anterior Tibial Translation - Places increased stress on ACL (Antagonist) MALE Hamstring Dominant: - Anterior Tibial Translation is Decreased - ACL load is decreased significantly (Agonist) Hewett et al, 1996
    • 25. Preparatory and Reactive Muscle Activity • Effectively coordinate muscle activity to protect a joint requires a quick reaction at the muscle level • The time taken to generate muscle activity and produce an adequate force will determine dynamic stabilization Lephart et al, 2002
    • 26. Force Production w/shorter Electromechanical Delay (EMD) • EMD is the latency period between preparatory and reactive muscle activation • Men have a shorter EMD than women • Thus, men demonstrate a quicker response time for force production than women Hakkinen et al, 1991 Osternig et al, 1983
    • 27. Landing Characteristics • High % of ACL injuries occur when the athlete lands from jump – Ground Reaction Force (GRF) 3-14x body weight • Stiff legged landing increases GRF significantly – Gender differences seen in knee angles when landing from jump
    • 28. Landing Characteristics (cont) • Huston, 2000 – 20 height matched subjects (10 men / 10 women) – Unconstrained jumps at 20, 40, 60 cm – Impact Landing: Women averaged 7° knee flexion compared with Men 16°
    • 29. Land Characteristics (cont)
    • 30. Landing Characteristics (cont) • Malinzak et al, 1999 • Compared kinematic data on young healthy men and women during controlled running and cutting maneuvers • Results from comparison – Less knee flexion (25° vs 29°) – Increased knee valgus (knees pointing inward) – Less hip flexion
    • 31. ACL Tear Prevention Is it Possible? YES!! Several prospective studies have shown an 4 to 8-fold decreased rate on ACL tears in female athletes who are properly trained Hewett TE, Lindenfeld TN, Riccobene JV, Noyes FR. The effect of neuromuscular training on the incidence of knee injury in female athletes. A prospective study. Am J Sports Med. 1999 Nov-Dec;27(6):699-706. Mandelbaum BR, et al. AOSSM Annual Meeting, 2002, Disneyland FL
    • 32. Training Program (Smarter not Harder) • What now?? • An effective jumping and training program has shown significant improvements on all previously highlighted EXTRINSIC FACTORS associated with the increase in ACL injuries • Properly trained female athletes can decrease their ACL tear rate equal to that of males • Studies show that it can also increase your vertical leap by 10%
    • 33. CD-ROM Exercise Program Demonstration
    • 34. Specificity of Training is the Key to Injury Prevention • Still a GREAT program with male population • Preventing musculoskeletal injuries with PROPER exercises should be the backbone of orthopedic medicine • Proper education is the forefront to success
    • 35. QUESTIONS?
    • 36. References • Flynn JM, Lou JE. Ganley TJ. Prevention of sports injuries in children. Current Opinion in Pediatrics. 14(6):719-22, 2002 Dec. • Gollehon DL, Torzilli PA. The role of the posterolateral and cruciate ligaments in the stability of the human knee. A biomechanical study.; Warren-RF J-Bone- Joint-Surg-Am. 1987 Feb; 69(2): 233-42 • Hewett et al, Plyometric Training in Female Athletes. Am J Sports Med. 1996 • Hewett et al, The Effect of Neuromuscular Training on the Incidence of Knee Injury in Female Athletes. Am J Sports Med. 1999. • Huston LJ, Greenfield ML. Wojtys EM. Anterior cruciate ligament injuries in the female athlete. Potential risk factors. Clinical Orthopaedics & Related Research. (372):50-63, 2000 Mar. • Lephart et al, Neuromuscular Contributions to Anterior Cruciate Ligament Injuries in Females. Rheumatology. 2002. • Loud KJ, Micheli LJ. Common athletic injuries in adolescent girls. Current Opinion in Pediatrics. 13(4):317-22, 2001 Aug. • Messina et al, The Incidence of Injury in Texas High School Basketball. Am J Sports Med. 1999.
    • 37. References • Odensten M, Gillquist J. Functional anatomy • Walsh et. al. Sportsmetric: Neuromuscular Training to Prevent Knee Injuries. Cincinnati Sports Medicine Research and Education Foundation. 2002. • White et al, EMG Power Spectra of Intercollegiate Athletes and Anterior Cruciate Ligament Injury in Females. Med and Sci in Sports & Exercise. 2003 • Wojtys et al. Gender Differences in Muscular Protection of the Knee in Torsion in Size-Matched Athletes. J Bone and Joint Surg Am. 2003 • Wojtys et al. Neuromuscular Performance in Normal and Anterior Cruciate Ligament – Deficient Lower Extremities. Am J Sports Med. 1996

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