ESS 303

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ESS 303 Biomechanics

• Hip Joint

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?/? Differences (Women)

• Entire pelvic girdle tilted forward
• Bones thinner and lighter
• Greater distance between greater-superior iliac
  spines (wider greater or false pelvis)
• Wider and more spherical true pelvis
• More triangular obturator foramen
• Shallower symphasis pubis
• Wider more rounded pubic angle

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Sacral Positions
Neutral
Sacral Flexion (With Trunk Extension)
Sacral Extension (With Trunk Flexion)
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6 Pelvic Positions

• Anterior tilt (with trunk flexion or thigh
  extension)
• Posterior tilt (with trunk extension or thigh
  flexion)
• Left lateral tilt (left side drops)
• Right lateral tilt (right side drops)
• Left rotation (left back/right forward)
• Right rotation (right back/left forward)

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4 Femur Neck Angles

• Angle of inclination
• 125º is normal
• gt125º is coxa valga
• lt125º is coxa vara
• Angle of torsion
• 12 to 14º is normal
• Head forward is anteversion or internal femoral
  torsion (toeing in) common usually outgrown
  in children
• Head back is retroversion (toeing out)

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4 Femur Neck Angles

• Angle of Wiberg
• Increases with age
• Male about 38
• Female about 35
• Acetabular anteversion
• Male about 18.5
• Female about 21

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Some Final Notes

• Roundness of acetabulum decreases with age
• Transmision of forces between upper and lower
  extremities
• Acetabular labrum (fibro-cartilage lip)
• Adds stability
• Deepens socket
• Increases concavity
• Grasps head

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Movements and Major Muscles

• Adduction Gracilis adductors (longus, brevis
  magnus)
• Abduction Gluteus medius gluteus minimus
• Flexion Iliopsoas (iliacus psoas major)
  rectus femoris
• Extension Gluteus maximus hamstrings
  (semitendinosus, semimembranosus biceps
  femoris)
• Internal (medial) rotation Gluteus medius,
  gluteus minimus
• External (lateral) rotation Gluteus maximus,
  adductor brevis aductor magnus
• Circumduction, horizontal (transverse) abduction,
  horizontal (transverse) adduction,
  hyperabduction, hyperadduction Hyperextension
  Combinations or exaggerations of above