ESS 303 – Biomechanics Hip Joint
Jan 29, 2016
ESS 303 – Biomechanics
Hip Joint
♀/♂ Differences (Women)
Entire pelvic girdle tilted forwardBones thinner and lighterGreater distance between greater-
superior iliac spines (wider greater or false pelvis)
Wider and more spherical true pelvisMore triangular obturator foramenShallower symphasis pubisWider & more rounded pubic angle
Sacral Positions
NeutralSacral Flexion(With Trunk Extension)
Sacral Extension(With Trunk Flexion)
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)
4 Femur Neck Angles
1. Angle of inclination=125º is normal>125º is coxa valga<125º is coxa vara
2. Angle of torsion12 to 14º is normalHead forward is anteversion or internal femoral
torsion (toeing in) – common & usually outgrown in children
Head back is retroversion (toeing out)
4 Femur Neck Angles
3. Angle of Wiberg
Increases with age
Male: about 38°
Female: about 35°
4. Acetabular anteversion
Male: about 18.5°
Female: about 21°
Some Final Notes
Roundness of acetabulum decreases with age
Transmision of forces between upper and lower extremities
Acetabular labrum (fibro-cartilage lip)Adds stabilityDeepens socketIncreases concavityGrasps head
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