1. ESS 303 – Biomechanics
Hip Joint

3. ♀/♂ 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

5. (With Trunk Extension)
Sacral Positions
Sacral Flexion
(With Trunk Extension)
Neutral
Sacral Extension
(With Trunk Flexion)

6. 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)

8. 4 Femur Neck Angles Angle of inclination Angle of torsion
=125º is normal
>125º is coxa valga
<125º 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)

9. 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°

10. 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

11. 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