Lower Extremity Consequences of  Core Dysfunction

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Lower Extremity Consequences of Core Dysfunction

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1. Lower Extremity Consequences of “Core Dysfunction” Joseph M. Hart, PhD, ATC University of Virginia Orthopaedic Surgery Sports Division

2. Introduction “Core stability may provide several benefits to the musculoskeletal system, from maintaining low back health to preventing knee injury” Willson J D, Dougherty C P, Ireland M L, and Davis I M, Core stability and its relationship to lower extremity function and injury. J Am Acad Orthop Surg, 2005. 13(5): 316-25.

3. What is the “core”? What is “core stability”?

4. Where is the “core” Lumbo-pelvic-hip complex Includes the active & passive structures that either produce or restrict movements of the lumbar, hip or pelvic segments

5. What is the “core”? Movements/ stability occurs in 3 planes Sagittal Plane Frontal Plane Transverse Plane

6. What is the “core”? Sagittal Plane stability Rectus abdominis transverse abdominis erector spinae multifidus gluteus max hamstrings Flexion/ extension Co-contraction causes trunk stiffness and raises intra-abdominal pressure “rigid cylinder”

7. What is the “core”? Movements/ stability occurs in 3 planes Sagittal Plane Frontal Plane Transverse Plane

8. What is the “core”? Frontal Plane Glut med., glut min. (1º lateral hip stabilizers) Quadratus lumborum Unilateral: ipsilateral pelvis elevation Contralateral: spine stiffness Perhaps best suited for spine stability; active during nearly all upright tasks Hip adductors (magnus, longus, brevis, pectineus)

9. What is the “core”? Movements/ stability occurs in 3 planes Sagittal Plane Frontal Plane Transverse Plane

10. What is the “core”? Transverse Plane stability HIP rotation: glut max., glut med. Piriformis superior/inferior gemelli quadratus femoris obterator internus/externus Trunk rotation: internal/external obliques iliocostalis lumborum multifidus

11. What is the “core”? Thoraco-Lumbar Fascia Covers and inter-connects muscles and fascia surrounding the spine Helps create a stabilizing “corset” effect Provides connective support from LE to UE Allows for integrated kinetic chain activities

12. What is “core stability”

13. What is “core stability” “The ability of the Lumbo-pelvic-hip complex to prevent buckling of the vertebral column and to return it to equilibrium following perturbation” Coordination and co-contraction of muscles provides spine stiffness “Rigid Cylinder”

14. What is “core stability” “…the ability to control the position and motion of the trunk over the pelvis and leg to allow optimum production, transfer and control of force and motion to the terminal segment in integrated kinetic chain activities.” Kibler W B, Press J, and Sciascia A, The role of core stability in athletic function. Sports Med, 2006. 36(3): 189-98.

15. What is “core stability” Core stability is “instantaneous” Must continually adapt to changing postures and loading conditions Ensure integrity of spine and provide stable base for movement of extremities. Absorb forces transmitted through the lower extremity during activity

16. Importance of core stability Mechanical base for motion of the distal segments Many extremity prime movers attach to the core Core muscles are active before initiation of extremity movement. “Proximal stability for distal mobility”

17. Importance of Core Stability Motor control Carefully coordinated contractions from antagonistic muscles is necessary to stabilize during posture, activity and to react to perturbations. Muscle activity assists with attenuating forces transmitted through the lower extremity to the spine during activity Neuromuscular training reduced serious knee injury in females by 62% (Hewett, 1999) Included abdominal curls, back extension exercise

18. Importance of Core Stability Muscular capacity( ie: endurance) Trunk muscle endurance is of greater value than the ability to generate force in the prevention of LBP (McGill, 2003)

19. Importance of Core Stability “…the product of motor control and muscular capacity of the lumbo-pelvic-hip complex.” Leetun D T, Ireland M L, Willson J D, Ballantyne B T, and Davis I M, Core stability measures as risk factors for lower extremity injury in athletes. Med Sci Sports Exerc, 2004. 36(6): 926-34.

20. Importance of Core Stability What is needed to achieve optimal stability? Depends on task/ activity Balance/ symmetry for co-contraction Endurance/ motor control during fatiguing tasks Same muscles that stabilize also needed for breathing at times of high O2 demand (fatiguing exercise) Loss of stabilization during high intensity exercise? --(McGill, 1995)

21. “What is: Core Dysfunction”

22. Core Dysfunction Poor/ altered function of muscles that stabilize the lumbar-pelvic-hip complex Causes? Muscle Weakness Poor muscular endurance Fatigue Pain/ injury avoidance The important question: What happens during activity when muscles cannot stabilize the lumbar spine, pelvis and hips?

23. Core Dysfunction Lumbar spine experiences compressive loads >6000N Passive restraints able to resist only 90N Remaining support provided by active tissue What happens when muscles fatigue quickly or at different rates? COPING MECHANISM…..

24. Low Back Pain Core Dysfunction is common in persons with LBP

25. Low Back Pain Non-specific LBP presents a major clinical problem due to the likelihood of high cost, limited activity levels and recurrence. Back injuries account for 20% of all injuries and illnesses in the workplace 2% of the US workforce are compensated for back injuries each year Enormous economic burden ?$25 billion annually

26. Low Back Pain The likelihood of experiencing LBP increases with age peak prevalence of LBP occurs in persons aged 55-64 years in US 85-90% of the population is likely to experience an episode of low back pain in their lifetime 2-5% of the population at least once every year. LBP causes the greatest level of activity level limitations in persons less than 45 years.

27. Low Back Pain Back pain etiology is multifactorial What do we know about risk for developing LBP? Previous LBP including (frequency and duration of symptoms) Weak, highly fatigable and unbalanced muscles Specifically, poor lumbar paraspinal endurance (Biering-Sorensen) Hamstring tightness Poor spinal flexibility Reduced lumbar lordosis

28. Back to the core…

29. The “core” question… How does fatigue affect muscular stability of the lumbar spine, pelvis and hips? In the presence of Recurrent Low Back Pain? Poor core stability How does this affect Lower Extremity muscle function? Lower extremity injury risk??

30. Research Findings Persons with LBP who fatigue quicker (lumbar extension endurance) tend to have more quadriceps inhibition Suter, 2001 Localized lumbar paraspinal muscle fatigue causes increased quadriceps inhibition Hart, et al, 2005

32. Central Activation Ratio (C.A.R.) CAR = estimate of muscle inhibition FMVIC ? Force of MU voluntarily recruited FSIB ? Force of MU electrically recruited FMVIC + FSIB ? Force of TOTAL MU pool

33. Research Findings Compensation for local lumbar paraspinal fatigue during gait Similar to avoidance strategy observed in persons with injured/ reconstructed knee -Hart et al 2005

34. Research Findings Postural compensation for local lumbar fatigue Forward trunk posture (Madigan, 2006) More anterior COP during stance Redistribution of ankle, knee and low back torques during stance How will this affect Gait?

35. Is trunk forward lean bad?

36. Is trunk forward lean bad? Anteriorly displaced ground reaction force vector during activity/ gait Reduces sagittal plane knee joint moment Indicates quadriceps eccentric control during gait

38. Trunk Forward Lean Alters force attenuation at the knee Etiology or forward lean? Weak Gluteals? Weak Quadriceps? Weak Lumbar paraspinals Poor endurance in muscles that stabilize pelvis, spine, hips? Sequellae? Higher thoraco-lumbar disc loads Quadriceps atrophy/ weakness LE joint surfaces exposed to unusual/ excessive forces

39. Trunk Forward Lean “Flat-back” patients show similar gait adaptations to persons with knee OA Reduced velocity, reduced stride length, increased stance phase duration Note continued high force during mid-stance in persons with forward flexed trunk posture during gait

40. Trunk Forward Lean Compensation for forward flexed position of the trunk is a crouched posture Flexed knee and hip in stance and during gait (also similar to patients with advanced OA) Places weaker gluteals in a mechanically advantaged position Higher demand on quadriceps

41. Core Stability and LE Injury Inappropriate positions of hips and trunk during gait or landing may place LE joints at risk for injury Inability of hip rotators to control femur rotation ? knee valgus/ internal rotation

42. Gait Compensations Persons recurrent LBP exhibit a quadriceps dominant pattern during gait. (Hart, 2005) Adaptation to poor spine, pelvis, hip muscular stability?

43. Gait Compensations What other group exhibits quadriceps dominance, trunk lean, poor control of femur rotation? “position of no return” Body forward flexed Hip adducted Internally rotated Valgus knee Tibia externally rotated Foot pronated

44. Review Persons with poor Lumbo-pelvic-hip stability During exercise Fatigue: Deteriorated postural control Difficult for hip muscles to appropriately position femur during gait, landings, etc Trunk Forward Lean Re-distributing Lower extremity forces during gait Inhibited Quadriceps Reduced knee joint torque during gait Reliance on proximal, postural muscles (which are probably weak, inhibited, poor endurance) What absorbs forces if muscles cannot?

45. Discussion… “Core stability may provide several benefits to the musculoskeletal system, from maintaining low back health to preventing knee injury”

46. Thank you for your attention…

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