- The hip joint is a synovial joint of the ball and socket variety.
- It is a very strong and stable joint due to its structure and supporting ligaments.
- Homologous to the shoulder joint of the upper limb but more stable.
- Allows a wide range of movements similar to the shoulder.
Articular Surface:
- Proximally: The acetabulum of the hip bone (horse-shoe-shaped cavity on the lateral side).
- Distally: The head of the femur, which forms more than half of a sphere.
- The head of the femur is covered with hyaline cartilage.
- The acetabular labrum (fibrocartilaginous rim) deepens the cavity for stability.
Mnemonic for Stability: "CATS"
- Capsular Ligament
- Acromioclavicular Pressure
- Tension of Ligaments
- Strength of Muscles
Ligaments:
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Capsular Ligament:
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Surrounds the joint, attached to the acetabular margin and intertrochanteric line (anteriorly) and intertrochanteric crest (posteriorly).
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Thick and strong anterosuperiorly, thin posteroinferiorly.
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Iliofemoral Ligament:
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"Y" shaped and one of the strongest ligaments.
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Lies anteriorly, from the anterior inferior iliac spine to the intertrochanteric line.
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Pubofemoral Ligament:
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Triangular in shape, supports inferomedially.
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Attached from the ilio-pubic eminence to the femur.
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Ischiofemoral Ligament:
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Comparatively weak, supports posteriorly.
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Extends from the ischium to the acetabulum.
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Ligament of the Head of Femur:
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Flat and triangular, apex at fovea capitis, base at transverse ligament.
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Transverse Ligament of the Acetabulum:
- Bridges the acetabular notch.
Relations:
- Anterior: Tendon of iliopsoas.
- Posterior: Tendon of obturator externus.
- Superior: Gluteus maximus, gluteus minimus, and gluteus medius muscles.
- Inferior: Adductor longus, adductor brevis, and adductor magnus muscles.
- Laterally: Tensor fasciae latae and gluteus medius.
- Medially: Obturator internus and adductor muscles.
Blood Supply:
- Obturator artery.
- Medial and lateral circumflex femoral arteries.
Nerve Supply:
- Obturator nerve.
- Femoral nerve.
- Superior gluteal nerve.
Movements:
- Flexion: Performed by iliopsoas, rectus femoris.
- Extension: Performed by gluteus maximus.
- Abduction: Performed by gluteus medius and minimus.
- Adduction: Performed by adductor longus, brevis, magnus.
- Medial Rotation: Performed by gluteus medius and minimus.
- Lateral Rotation: Performed by piriformis, obturator internus.
- Circumduction: Combination of flexion, extension, abduction, and adduction.
Mnemonic for Movements: "FAME LABC"
- Flexion
- Abduction
- Medial rotation
- Extension
- Lateral rotation
- Adduction
- Body movement (Circumduction)
- Complex motion
Clinical Anatomy:
- Congenital Dislocation: Due to shallow acetabulum.
- Tuberculosis of Hip Joint: More common in children under 5 years.
- Perthe's Disease: Affects children aged 5-10 years.
- Coxa Vera: Common between 10-20 years.
- Osteoarthritis: Typically after 40 years.
- Fracture of Neck of Femur: Common in elderly due to osteoporosis.
- Hip Joint Injuries:
- In children: Displacement or greenstick fractures.
- In elderly: Fracture of the neck of femur.
