Hip Joint Lecture Notes

Introduction to Hip Joint

• Type of Joint: Ball and socket joint, classified as a synovial joint.
• Function: Connects axial skeleton to lower extremities; supports static (standing) and dynamic (walking, running, weight-bearing) activities.

Joint Capsule

• Structure: Strong and fibrous but loose; accommodates a wide range of movements.
• Attachments: Attaches to acetabular labrum, transverse acetabular ligament, and intertrochanteric line of femur.

Ligaments of the Hip Joint

Outer Ligaments

1. Iliofemoral Ligament

   • Attachment: Anterior inferior iliac spine to acetabulum and intertrochanteric line.
   • Function: Prevents excessive lateral rotation and hyperextension; strongest ligament in the body.

2. Ischiofemoral Ligament

   • Attachment: Originates from acetabulum rim to greater trochanter.
   • Function: Reinforces fibrous capsule, prevents excessive medial rotation and extension of the thigh.

3. Pubofemoral Ligament

   • Attachment: Arises from pubic ramus, merges with iliofemoral ligament.
   • Function: Reinforces capsule inferiorly and limits abduction and extension of the thigh.

Inner Ligaments

1. Transverse Acetabular Ligament

   • Function: Covers acetabular notch, forms acetabular foramen for vessels/nerves.

2. Ligament of the Head of the Femur

   • Attachment: Arises from acetabular notch to fovea of femur.
   • Function: Contains foveolar artery, provides blood supply to femoral head.

Hip Joint Movements and Biomechanics

• Muscles and Movements:

  • Flexion: Psoas major, iliacus, sartorius, rectus femoris, and bacterius.
  • Extension: Gluteus maximus and hamstring muscles (semimembranosus, semitendinosus, biceps femoris).
  • Abduction: Gluteus medius, gluteus minimus, tensor fasciae latae.
  • Adduction: Adductor longus, adductor brevis, adductor magnus, gracilis, pectineus.
  • Internal Rotation: Psoas major, iliacus, sartorius.
  • External Rotation: Obturator muscles, gemelli, quadratus femoris, gluteus maximus, piriformis.

• Range of Movements (with knee flexed):

  • Flexion: 140°
  • Extension: 15°
  • Abduction: 40°
  • Adduction: 25°
  • Internal Rotation: 35°
  • External Rotation: 45°

Blood Supply of the Hip Joint

• Major Contributors: Medial and lateral circumflex arteries (branches of femoral artery).
• Minor Contributor: Artery of the head of the femur.
• Femoral Head Vulnerability: Avascular necrosis risk from lateral and ascending branches due to femoral neck fractures.
• Ligamentum Teres Artery: Main supply to femoral head in children; disrupted in hip dislocations.

Nerve Supply of the Hip Joint

• Innervation Sources:
  • Anteriorly: Femoral nerve (main)
  • Inferiorly: Anterior division of obturator nerve
  • Laterally: Articular branch of sciatic nerve
  • Posteriorly: Nerve to quadratus femoris, superior gluteal nerve

Clinical Anatomy: Hip Dislocation

• Definition: Disruption of joint between femur and pelvis.

• Symptoms: Pain and inability to move hip; complications include avascular necrosis and nerve injuries.

• Types of Dislocations:

  • Posterior Dislocation: Most common (90%). Limb in flexion, adduction, and internal rotation; potential sciatic nerve palsy (8-20%).
  • Anterior Dislocation: Less common; limb held in external rotation and mild flexion/abduction; potential femoral nerve palsy.

• Causes: High degree of force, primarily from motor vehicle collisions (65% of cases).

• Diagnosis:

  • Anterior-posterior X-rays of pelvis and lateral views of femur; CT scan may be used for fracture clarification.
  • Affected femoral head may appear larger (anterior dislocation) or smaller (posterior dislocation).

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These notes summarize the key points discussed in the lecture on the hip joint, focusing on its anatomy, movements, blood supply, nerve supply, and clinical considerations.