BASIC SCIENCE OF TENDON

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BASIC SCIENCE OF TENDON

• Richard E. Hughes, Ph.D.
• Orthopaedic Surgery

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OUTLINE

• Structure
• Function
• Attachments
• Measurement
• Effect of exercise
• Conclusions

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TENDON SHEATH
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TENDON STRUCTURE
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FIBER SIZE
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FIBER ORGANIZATION
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COLLAGEN FIBRIL
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TENDON BIOCHEMISTRY

• 65-75 collagen
• 98 of this is Type I
• 2 elastin
• Remainder is proteoglycans, glycosaminoglycans,
  and structural glycoproteins

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OUTLINE

• Structure
• Function
• Attachments
• Measurement
• Effect of exercise
• Conclusions

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TENDON FUNCTION

• Transmit tensile force from muscle to bone
• Store energy
• Allows muscle to be placed proximally reduces
  limb moment of inertia

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SPRING MODEL OF TENDON
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LOAD-DISPLACEMENT CURVE
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STRESS AND STRAIN

• StressForce/Area
• Strain(L-Lo)/Lo
• Logage length

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STRESS-STRAIN CURVE
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VISCOELASTIC MATERIAL
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TENDON FUNCTION

• Transmit tensile force from muscle to bone
• Store energy
• Allows muscle to be placed proximally reduces
  limb moment of inertia

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ELASTIC ENERGY STORAGE
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HUMAN RUNNING

• Runner loses and regains 100 Joules per stride at
  4.5 m/s pace
• 35 Joules stored in Achilles tendon
• 17 Joules in arch of foot
• Remainder in muscle

Alexander, R. M. (1988) Elastic mechanisms in
animal movement
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ELASTIC ENERGY STORAGE
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TENDON FUNCTION

• Transmit tensile force from muscle to bone
• Store energy
• Allows muscle to be placed proximally reduces
  limb moment of inertia

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MOMENT OF INERTIA
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OUTLINE

• Structure
• Function
• Attachments
• Measurement
• Effect of exercise
• Conclusions

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ATTACHMENT TO MUSCLE
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ATTACHMENT TO BONE
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OUTLINE

• Structure
• Function
• Attachments
• Measurement
• Effect of exercise
• Conclusions

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LONG HEAD OF BICEPS

• Hypothesis Rotator cuff tear causes hypertrophy
  of long head of biceps

Carpenter, J.E. et al. (2005) Clin. Biomech.
20162-165
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LONG HEAD OF BICEPS
Derwin, K.A. et al. (1994) J. Biomech. 27
1277-1285
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LONG HEAD OF BICEPS
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LONG HEAD OF BICEPS
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LOAD-DISPLACEMENT CURVE
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LOAD-DISPLACEMENT
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LHB RESULTS

• Cross sectional area .15 cm2
• Modulus 629 Mpa
• Ultimate load 305 N
• Ultimate stress 45.1 Mpa
• Ultimate strain .18

Carpenter, J.E. (2005) Clin. Biomech. 20162-165
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OUTLINE

• Structure
• Function
• Attachments
• Measurement
• Effect of exercise
• Conclusions

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EFFECT OF TRAINING
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OUTLINE

• Structure
• Function
• Attachments
• Measurement
• Effect of exercise
• Conclusions

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CONCLUSIONS

• Structure mostly collagen aligned
  longitudinally organized into fiber, fibril,
  subfascicle, fascicle, fiber bundle, and tendon
• Function transmit forces from muscle to bone
  store and release energy allow proximal muscle
  placement

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THANK YOU
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LONG HEAD OF BICEPS

• Hypothesis Rotator cuff tear causes hypertrophy
  of long head of biceps

Carpenter, J.E. et al. (2005) Clin. Biomech.
20162-165
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THINGS I NEED

• Hand weight
• Rubber band

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ENERGY STORAGE IN FOOT
Alexander, R. M. (1988) Elastic mechanisms in
animal movement
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TENDON CRIMP
UNLOADED
LOADED
SEM OF UNLOADED TENDON