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Structure

Hip joint

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This is the date the draft was written, not a medical review date.

The hip is a deep synovial ball-and-socket joint between the femoral head and the acetabulum. It combines a wide range of movement with great stability, as required for weight bearing and gait.

Terminologia Anatomica (Latin): Articulatio coxae · Open in the 3D atlas

Location

It lies deep in the groin and gluteal region. The femoral artery, vein and nerve pass anterior to the joint, and the sciatic nerve passes behind it.

Structure

The acetabulum is deepened by the labrum and bridged inferiorly by the transverse acetabular ligament. The strong capsule is reinforced by the iliofemoral (strongest), pubofemoral and ischiofemoral ligaments; the ligament of the head of the femur carries a small artery. The capsule encloses most of the femoral neck.

Blood supply

The medial and lateral circumflex femoral arteries (from the profunda femoris) form a ring around the femoral neck and give retinacular branches to the head. Obturator and gluteal arteries contribute to the acetabulum; the artery of the ligament of the head is of minor importance in adults.

Innervation

Branches of the femoral, obturator, superior gluteal nerves and the nerve to quadratus femoris supply the capsule. Because the obturator nerve also supplies the knee, hip disease can present as knee pain.

Function

Movements are flexion, extension, abduction, adduction, medial and lateral rotation and circumduction. The joint transfers body weight from the pelvis to the femur; during single-leg stance the gluteus medius and minimus keep the pelvis level.

Clinical correlations

Posterior dislocation (for example in road accidents) may injure the sciatic nerve. Femoral neck fractures can compromise the head's blood supply. In developmental dysplasia of the hip, early detection in infants matters. A positive Trendelenburg sign suggests superior gluteal nerve or abductor weakness. Osteoarthritis and slipped capital femoral epiphysis (adolescents) are common.

Common exam points

  • Iliofemoral ligament is the strongest ligament of the body and limits hyperextension.
  • Retinacular branches of the medial circumflex femoral artery supply most of the femoral head.
  • Posterior dislocation: leg shortened, flexed, adducted and medially rotated; sciatic nerve at risk.
  • Trendelenburg sign: pelvis drops on the unsupported side when standing on the affected leg.
  • Hip pathology may be referred to the medial thigh and knee (obturator nerve).

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Netter FH. Atlas of Human Anatomy. Elsevier — Tier 3 (textbook)

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