The document discusses the biomechanics of the hip complex, including its articulations, angles, ligaments, musculature, and kinematics. Key points include descriptions of the proximal and distal articular surfaces, angles of inclination and torsion, capsular ligaments, weight bearing structures, and osteokinematics of the femur and pelvis during motions like flexion, extension, abduction, and rotation. Gait and stance mechanics are analyzed, such as bilateral stance, unilateral stance, and trunk listing with calculations of joint torques and forces.

1. THE HIP COMPLEX
BIOMECHANICS
Sreeraj S R

2. Articulations of the Hip and Pelvis
Sreeraj S R

3. PROXIMAL ARTICULAR SURFACE
• Faces laterally
• Faces anteriorly
– 18.5o males
– 21.5o women
• Faces inferiorly
– 22o - 42o range
– 38o in males
– 35o in females
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4. Proximal articular surface…
• Center Edge angle
• Acetabular Anteversion
• Acetabular Labrum
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5. DISTAL ARTICULAR SURFACE
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6. ANGLE OF INCLINATION
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7. ANGLE OF TORSION
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8. Angle of torsion…..abnormal
• Anteversion
• Retroversion
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9. ARTICULAR CONGRUENCE
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10. CAPSULE
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11. LIGAMENTS
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12. WEIGHT BEARING STRUCTURE
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13. ARTHROKINEMATICS
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14. OSTEOKINEMATICS
Sagittal plane motions of the femur at the hip joint
• Flexion: 90o-135o
• Extension: 0o-30o
• Role of 2 joint muscles?
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15. OSTEOKINEMATICS
Frontal plane motions of the femur at the hip joint
• Abduction: 30o-50o
• Adduction: 10o-30o
• Role of 2 joint muscles?
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16. OSTEOKINEMATICS
Frontal plane motions of the femur at the hip joint
• IR (extension*) : 35o-45o
• IR (flexion**) : 30o-45o
• ER (extension*) : 45o-50o
• ER (flexion**) : 45o-60o
*Extension = Neutral –Terminal
**Flexion = 900
Sreeraj S R

17. OSTEOKINEMATICS
motions of the femur at the hip joint during functional activities
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18. OSTEOKINEMATICS
Sagittal plane Motions of the Pelvis at the Hip Joint
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19. OSTEOKINEMATICS
Frontal plane Motions of the Pelvis at the Hip Joint
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20. OSTEOKINEMATICS
Transverse Plane Motions of the Pelvis at the Hip Joint
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21. Open Kinematic Chain Motions:
Lumbo Pelvic Rhythm
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22. Closed Kinematic Chain Motions
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23. MUSCULATURE
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24. FLEXORS
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25. ADDUCTORS
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26. EXTENSORS
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27. ABDUCTORS
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28. LATERAL ROTATORS
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29. MEDIAL ROTATORS
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30. BILATERAL STANCE
• DR & DL : joint axis
• WR & WL : body weight
• Magnitude of
gravitational torque
around hip is : WR X DR
= WL X DL
• Total hip joint
Compression = 2/3 X
body weight
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31. Unilateral Stance
• Rt. hip joint compression = 2/3 X
W + 1/6 X W or 5/6 X W
• Magnitude of gravitational
adduction torque at Rt. hip i.e.
HATLL torque add = Rt. hip jt.
compression X 4”
• Magnitude of muscle
contraction or
Torque abd or Fms = Magnitude
of gravitational adduction torque
at Rt. hip ÷ 2”
• Total joint compression or joint
reaction force = Magnitude of
muscle contraction + Rt. hip
joint compression Sreeraj S R

32. Ipsilateral Trunk List
• Gravitational adduction
torque i.e.
HATLL Torque add = Rt. hip
joint compression X 1
• The abduction force needed
would be ,
Torque abd or Fms = HATLL
Torque add ÷ 2”
• Total joint compression or
joint reaction force =
Magnitude of muscle
contraction + Rt. hip joint
compression
Sreeraj S R

33. Ipsilateral Cane • Inman et al suggested that a
person can push down on a
cane with 15% of his body
weight.( body wt. X 0.15)
• Magnitude of HATLL = hip
jt. compression – body wt. X
0.15
• Torque add = Magnitude of
HATLL X 4”
• Torque abd = Torque add ÷
2”
• Total joint compression or
joint reaction force =
Magnitude of muscle
contraction + Rt. hip joint
compression Sreeraj S R

34. Contralateral Cane
• Magnitude of HATLL = hip jt.
Compression – body wt. X 0.15
• Torque add = Magnitude of HATLL
X 4”
• Counter torque by Latissimus
dorsi :
Torque Latissimus = body wt.
thrugh cane X 8”
• Unopposed adduction torque =
Torque add – Torque Latissimus
• Torque abd or Fms = Unopposed
Torque add ÷ 2”
• Total joint compression or joint
reaction force = Magnitude of
muscle contraction + hip joint
compression
Sreeraj S R