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KINESIOLOGY FOR ORTHOPEDICS (PowerPoint)

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KINESIOLOGY FOR ORTHOPEDICS (PowerPoint) Powered By Docstoc
					 JOINT LOADING

Richard E. Hughes, Ph.D.
 Orthopaedic Research
      Laboratories
 University of Michigan
                OUTLINE
• Biomechanical principles
• Methods for measuring/estimating loads
• Examples
  – Spine
  – Knee
  – Hip
  – Shoulder
• Conclusions
Force Components

     F
         • direction
         • magnitude
         • point of action
Force Components

y                 • direction
    Fx   F
                  • magnitude
                  • point of action
         Fy

              x      F = ( Fx , Fy )
      Ax = CCW moment
      By = CW moment
  A                         B




       x                y
x, y are moment arms
LIFTING A LEVER
MECHANICS OF LEVER



                 3F = 30FHAND

                      30
                 F=         FHAND
                       3
         FHAND
                 F = 10 FHAND
 F
MECHANICAL ANALYSIS




        FHAND

 F
NEWTON’S THIRD LAW




        FHAND



                FHAND
MECHANICS OF SPINE

                  2FMUSCLE = 12FHAND

                              12
                  FMUSCLE =        FHAND
                              2

                  FMUSCLE = 6 FHAND




FHAND   FMUSCLE
SEGMENTAL ANALYSIS
        DYNAMIC LIFTING
• Extra force required
  to accelerate box in
  hands
• Extra force required
  to accelerate body
  segments
• Extra moment
  required to rotate
  body segments
                OUTLINE
• Biomechanical principles
• Methods for measuring/estimating loads
• Examples
  – Spine
  – Knee
  – Hip
  – Shoulder
• Conclusions
  MEASURING/ESTIMATING
     JOINT LOADING

• Mathematical model
• Electromyographic (EMG) based
  methods
• Direct measurement with instrumented
  prosthesis
BIOMECHANICAL ANALYSIS
  MEASURING/ESTIMATING
     JOINT LOADING

• Mathematical model
• Electromyographic (EMG) based
  methods
• Direct measurement with instrumented
  prosthesis
ELECTROMYOGRAPHY
EMG ELECTRODES
  MEASURING/ESTIMATING
     JOINT LOADING

• Mathematical model
• Electromyographic (EMG) based
  methods
• Direct measurement with instrumented
  prosthesis
     INSTRUMENTED
       PROSTHESIS




Bergmann, G. et al. (2001) J. Biomech. 34:859-871
                OUTLINE
• Biomechanical principles
• Methods for measuring/estimating loads
• Examples
  – Spine
  – Knee
  – Hip
  – Shoulder
• Conclusions
INTER-DISCAL PRESSURE
          HEAVY LIFTING
• Lifting carbon pieces
  out of smelter
  electrochemical cell
• Pieces weigh 890 N
  (200 lbs)
• 3327 N (748 lbs)
  lumbar compression




     Hughes, R.E. (1995) Ergonomics 38:2476-2484
         LIGHT DUTY JOB
• Workers
  compensation LBP
  claimants return to
  this job
• No lifting
• 100% repeat claim
  rate
• Why?



     Hughes, R.E. (1995) Ergonomics 38:2476-2484
BIOMECHANICAL ANALYSIS




  LUMBAR SPINE COMPRESSION = 1372 lbs
MUSCLE ORIENTATION
                OUTLINE
• Biomechanical principles
• Methods for measuring/estimating loads
• Examples
  – Spine
  – Knee
  – Hip
  – Shoulder
• Conclusions
DYNAMIC ANALYSIS
         JOINT LOADING
• Methods
  – Moments measured from gait analysis
  – Muscle forces estimated from moments
  – Mathematical model
• Results
  – 3 x BW peak compression force
  – 1 x BW peak AP force
  – Minimal medial-lateral force

    Mikosz,R.P. et al. (1988) JOR 6:205-214.
                OUTLINE
• Biomechanical principles
• Methods for measuring/estimating loads
• Examples
  – Spine
  – Knee
  – Hip
  – Shoulder
• Conclusions
     INSTRUMENTED
       PROSTHESIS




Bergmann, G. et al. (2001) J. Biomech. 34:859-871
HIP ABDUCTION/ADDUCTION MOMENT
RESULTANT FORCES
              HIP LOADS




Bergmann, G. et al. (2001) J. Biomech. 34:859-871
    RESULTANT FORCE
  DURING STANCE PHASE
      OF WALKING
• 2.6-2.8 x BW (Davy et al., 1988, JBJS)
• 2.8 x BW (Bergmann et al., 1993, JB)
• 2.4 x BW (Bergmann et al., 2001, JB)
                OUTLINE
• Biomechanical principles
• Methods for measuring/estimating loads
• Examples
  – Spine
  – Knee
  – Hip
  – Shoulder
• Conclusions
  GLENOHUMERAL LOADING
• Method
  – Isometric arm
    abduction
  – Muscle force
    proportional to EMG
• Results
  – Max = 0.89 x BW
  – Max at 90o abduction


 Poppen, N.K. and Walker, P.S. (1978) CORR 135:165-170.
                OUTLINE
• Biomechanical principles
• Methods for measuring/estimating loads
• Examples
  – Spine
  – Knee
  – Hip
  – Shoulder
• Conclusions
Which of the following is the most likely contributory
           factor to joint reactive force?


        1.   Body and limb gravity
        2.   Joint deformity
        3.   Joint contact area
        4.   Ligamentous tension about the joint
        5.   Muscle contraction about the joint
Which of the following is the most likely contributory
           factor to joint reactive force?


        1.   Body and limb gravity
        2.   Joint deformity
        3.   Joint contact area
        4.   Ligamentous tension about the joint
        5.   Muscle contraction about the joint
          IMPLICATIONS
• Weight reduction reduces joint loading
  by multiples
• Interventions that reduce muscle
  moment arms may increase joint
  loading
THANK YOU