Bones - Hip Bone

Question 1

How many inomminate bones are there?

Answer 1

Two

Question 2

Articulations of the hip bone

Answer 2

Sacrum and ilium - to form sacroiliac joint.

Pubes - to form pubic symphysis

Acetabulum and femur - to form hip joint

Question 3

What three bones make up the hip bone?

Answer 3

1) Ilium - largest bone of the three
2) Ischium - sits inferiorly to the ilium
3) Pubis - inferiormedially to the ilium

These bones join at the tri-radiate cartilage that is found in the acetabulum. This cartilage fuses at around 15-17yo.

Question 4

Ilium

Bony landmarks?

Answer 4

1) Anterior superior iliac spine (ASIS) - anterior termination of iliac crest.
2) Anterior inferior iliac spine (AIIS) - located just inferiorly to the ASIS
3) Iliac crest - superior margin on the hip bone
4) Posterior superior iliac spine (PSIS) - posterior termination of the iliac crest.
5) Posterior inferior iliac spine (PIIS) - located just inferior to the PSIS.
6) Iliac fossa - hollow depression of the hip bone in the anterior view.
7) Greater sciatic notch - located inferior to the PIIS
8) Arcuate line of ilium - contributes to the linea terminalis (pelvic brim)
9) Auricular surface of ilium - articular surface that articulates with the sacrum.
10) Iliac tubercle - prominence found on the iliac crest.
11) Gluteal lines - site of attachment for muscles

Question 5

Clinical relevance: ASIS

Answer 5

1) Midinguinal ligament - halfway between the ASIS and centre of the pubic symphysis.
2) Femoral artery - halfway between ASIS and pubic tubercle.
3) True leg length - ASIS to medial malleolus

This can be a discrepancy in people with hip disorders or hip surgery.

4) Apparent leg length - umbilicus to medial malleolus

Question 6

Pubis

Bony landmarks?

Answer 6

1) Pubic body - located medially and articulates with the other body.
2) Superior aspect of the body is marked by the pubic crest.
3) Extending laterally from the crest is the pubic tubercle.
4) Inferolaterally to the body is the inferior pubic ramus.
5) Extending laterally from the body is the superior pubic ramus.
6) Iliopubic eminence - raised area located between the body of ilium and superior pubic of ramus - provides insertion point for the psoas minor muscle.
7) Obturator groove - located at the inferior aspect of the superior pubic ramus. The upper margin allows for attachment of the obturator membrane.

Question 7

Clinical relevance: pubic ramus fractures

Answer 7

Aetiology - usually low energy falls in the elderly, at standing height.

If isolated, these fractures are treated without surgery.

Healing can be expected in 6-8 weeks. Patients are encouraged to bear weight straight away.

Question 8

Ischium

Bony lands marks?

Answer 8

1) Inferior ischial ramus - combine with the inferior pubic ramus to form the ischiopubic ramus.
2) Ischial tuberosities - posteroinferior aspect of the ischium. When sitting, out these tuberosities support the body’s weight.
3) Ischial spine - sharp posteromedial projection

Question 9

Ligaments associated with the ischium

Answer 9

1) Sacrospinous ligament - ischial spine to the sacrum, creating the greater sciatic foramen. Sciatic nerve enters through here.
2) Sacrotuberous ligament - ischial tuberosity to the sacrum, formin the lesser sciatic foramen.

Question 10

Clinical relevance: pelvic fractures

Answer 10

There are two broad groups of pelvic fractures:

1) Low energy - osteoporotic patients resulting in pubic rami fractures. ‘Stable injuries’ not requiring surgery.
2) High energy - For example RTAs - may include acetabulum and SI joint. These will result in ‘unstable injuries’ and may require surgery. These can associated with soft tissue damage - bladder, urethra, and vascular injury.

Treatment - pelvic binders can be used to stabilise pelvis and minimise bleeding.