Knee Ligament Function 3 properties allow ligaments mechanical functions to limit motion: Attachment Location

Transcription

1 29 muscles attach Lumbar Spine Muscles Transversospinalis group Rotatores Interspinales Intertransversarii Semispinalis Multifidus Erector spinae Iliocostalis Longissimus Spinalis Quadratus lumborum Latissimus Dorsi Abdominal Muscles Rectus abdominus External obliques Internal obliques Transverse abdominus Core Functional Anatomy Work to optimize spinal mechanics Provide sagittal, frontal & transverse plane stabilization Knee Biomechanics: Stability of the Knee Geometry of the knee provides little stability. Therefore, the stability of the knee depends on static (passive) and dynamic (active) restraints. Compromised Passive Knee Restraints: Functional Consequences Knee Anatomy The knee provides the movements necessary for locomotion and allows for the support of large loads. The knee is the largest and one of the most complex joints in the body. tibiofemoral and patellofemoral Knee Stability: Passive Restraints Ligaments have 2 mechanical functions: Limit (gross) motion between bones tibia and femur Limit (micro) motion between articular cartilage surfaces tibia plateaus and femoral condyles Knee Ligament Function 3 properties allow ligaments mechanical functions to limit motion: Attachment Location

2 tibia and femur Just-taut length Controls motion before ligament provides resisting force Stiffness Controls movement after ligament taut Structure of the Knee: Static Restraints Collateral ligaments-major ligaments that cross the medial and lateral aspects of the knee Cruciate ligaments-major ligaments that cross each other in connecting the anterior and posterior aspects of the knee Motion of the Knee Joint: 6 Degrees of Freedom 3 Rotations: Flexion/Extension Abduction/Adduction InternalRotation/ External Rotation Motion of the Knee Joint: 6 Degrees of Freedom 3 Translations: Anterior/Posterior Medial/Lateral Compression/ Distraction Clinical tests at appropriate knee flexion angles: Contributions of primary and secondary restraints Knee Stability: Dynamic Restraints Kinematic and Kinetic Models from Markers & Ground Reaction Force Kinetics Newton (linear): F = m.a (Force = mass x linear acceleration) Euler (angular): M = I.a (Moment = mass moment of inertia x angular acceleration) ACL Failure Strength Load Curve for Ligament The ACL as a Sensor of Force and Torque Rich Innervation/Specific Mechanoreceptors

3 Kennedy, 1982 Schultz, 1984 Johansson, 1991 The ACL is: Sensitive Vulnerable Female Athletes suffer knee injuries at a rate 4-6 times greater than males playing same sport Chandy & Grana High School Sports 4.6 X Phys Sportsmed, 1985 Gray et al. Semi-Pro Basketball 5.0 X Phys Sportsmed, 1987 Ferreti et al. Pro Volleyball 4.0 X AJSM, 1992 Malone et al. Collegiate Sports 6.2 X J. S. Orth. Assoc, 1993 Arendt and Dick Collegiate Sports 2-4 X AJSM, 1995 Why is the Female ACL MORE Vulnerable? Examine the Injury Mechanism: Knee Abduction Low flexion Single leg COM away from foot base What Makes the Female ACL MORE Vulnerable? Identify Parallel Neuromuscular Imbalances: Knee Abduction Ligament Dominance Low flexion Quadriceps Dominance Single leg Leg Dominance COM Away from foot base Trunk Dominance

4 How to Make the Female ACL LESS Vulnerable Address the Mechanism: Knee Abduction Biomechanics/Technique Low flexion Power- H/Q recruit Single leg Balance/Symmetry COM Away from foot base Core Stability Potential Neuromuscular Imbalances Coronal Plane Mechanism: Dynamic Valgus =Decreased Coronal Plane Control 3-D Biomechanical Study High Force and Torque on Landing Sagittal Plane: increased subluxations reproduce the injury mechanism Quadriceps Dominance: Relative Flexor-Extensor Activation Side-to-Side Differences Mechanisms for ACL Injury Rate Disparity: Our Multi-Directional Approach Pubertal Growth and Development: Female-Male Divergence r s to Injury Risk Divergence in ACL injury rates between male and female athletes begin around age 12 - majority of females begun puberty. Shea et al ACL injuries peak in females at age 16. (AAOS) Garrett et al. 2003

5 Motion patterns in Pre-pubescent Female Pubertal Effects on Dynamic Knee Valgus Changes in Knee Abduction Moment with Maturation Pubertal Effects on Growth & GRF Absence of A Neuromuscular Spurt Growth and Development: Working Theory Dynamic Neuromuscular Control: Injury Predictor? Female - Lateral Trunk Lean to Knee Trunk to Knee Female - Lateral Trunk Lean Male - No Lateral Trunk Lean Is it possible to identify the high-risk female athlete? Longitudinal Studies of Trunk Growth, COM, Strength & Knee Abduction Load Prospective Biomechanical Core Stability Trunk Proprioception vs. Knee Injury Prospective Trunk Stability vs. Knee Injury Prospective Trunk Stability vs. Knee Injury Prospective Trunk Stability vs. Knee Injury Prospective Trunk Stability vs. Knee Injury 3-D Biomechanical-Epidemiological Coupled Research Hypotheses: Pre-screened females with subsequent ACL injury would demonstrate:

6 decreased neuromuscular control increased joint loading predict ACL injury risk 3-D Biomechanical-Epidemiological Coupled Research Method: 205 female athletes: 9 subsequently suffered confirmed ACL tears Prospectively measured neuromuscular control 3-D kinematics (angles) joint loads using kinetics ( moments) ANOVA, linear and logistic regression isolate predictors of risk athletes who subsequently ruptured their ACL Effects of Valgus Loading on ACL Injury Effects of Knee Angle on ACL Injury Results: Scattergram of Abduction Angle Effects of Valgus Loading on ACL Injury Results: Abduction Torque by Individual Dynamic Valgus Loading and ACL Injury GRF Loading and ACL Injury Components of Dynamic Valgus Predicted ACL Injury Risk KAbM and KAbA correlated to GRF and HAdM KFA did not correlate to GRF and HAdM Coronal Plane >>> Sagittal Plane KAbM predicted ACL injury: 73% specificity and 78% sensitivity Dynamic valgus measures: Predictive r 2 value of 0.88 Leg differences ½ the measures Reverse Elimination analysis Clinical Relevance Increased dynamic valgus and abduction loads = Increased risk of ACL

7 Field Methods (Camcorders, Portable Force Plates) may monitor/develop simpler measures neuromuscular control Direct high-risk female athletes to more effective, targeted interventions Recommendations Females athletes should be trained in pre-season especially those with: 1, 2, 3 or 4 neuromuscular imbalances: Excessive dynamic valgus Low hamstring strength Side-to-side differences in: Strength, Coordination, Balance Poor trunk stability ACL Workshop: Preventive and Rehabilitation Strategies November 6, 2010 Cincinnati Children s MERC Building One day workshop dedicated to the female athlete Always the 1 st Saturday in November Special afternoon session highlighting the prevention and rehabilitation of the ACL For more information call or visit Thank You & The Team! Acknowledgements: Cincinnati Children s Kevin Ford, PhD Mark Paterno, MS, PT Greg Myer, MS Kim Foss, MS Frank Biro, MD Jensen Brent

8 Laura Schmitt, PhD, PT Carmen Quatman, PhD Jon Divine, MD Jeff Robbins, PhD Danny Carson, MS Sam Wordeman Dai Sugimoto, MS Edwin Hewett Thanks to The Hewett Sisters My Inspiration Thank You & The Team! Acknowledgments: Cincinnati Children s Kevin Ford, PhD Mark Paterno, MS, PT Greg Myer, MS Kim Foss, MS Frank Biro, MD Jensen Brent Laura Schmitt, PhD, PT Carmen Quatman, PhD Jon Divine, MD Jeff Robbins, PhD Danny Carson, MS Sam Wordeman Dai Sugimoto, MS Eddie Hewett Thank You! Acknowledgments: Cincinnati Children s Greg Myer, MS, CSCS Kevin Ford, MS Mark Paterno, MS, PT Kim Foss, MS Frank Biro, MD

9 Jensen Brent Laura Schmitt, PhD, PT Carmen Quatman Adam Kiefer Jon Divine, MD Jeff Robbins, PhD ACL Injury Prevention Interventions Unanticipated Hops to Stabilization