Joints - Hip

Question 1

What type of joint is the hip joint?

Answer 1

Ball and socket

Question 2

Articulating surfaces?

Capsule?

Answer 2

Head of femur and acetabulum of the pelvis.

The acetabulum is deepened by a fibrocartilaginous ring, called the acetabulur labrum.

The capsule is attaches to the edge of the acetbulum proximally and the intertrochanteric line, distally.

Question 3

Ligaments?

Answer 3

Intracapsular

1) Ligament of the head of femur - acetabular fossa to the fovea of the femur.

It encloses a branch of the obturator artery (minor arterial supply to the hip joint).

Extracapsular

1) Iliofemoral ligament - AIIS and then bifurcates, inserting into the intertrochanteric line.
2) Pubofemoral ligament - superior pubic rami and intertrochanteric line.
3) Ischiofemoral ligament - body of ishcium and greater trochanter of femur.

Question 4

Neurovascular supply?

Answer 4

Arterial supply

1) Medial circumflex artery (profunda femoris) - main supply
2) Lateral circumflex (branch of profunda femoris)

Innervation

1) Sciatic nerve
2) Femoral nerve
3) Obturator nerve

Question 5

Movements?

Answer 5

1) Flexion - iliopsoas, rectus femoris, sartorius, pectineus
2) Extension - gluteus maximus, semimembranous, semitendinosus, biceps femoris (hamstrings)
3) Abduction - gluteus medius, gluteus minimus, piriformis, tensor fascia latae
4) Adduction - adductors longus, brevis and magnus, pectineus and gracilis
5) Lateral rotation - biceps femoris, gluteus maximus, piriformis, assisted by obturators, gemilli and quadratus femoris
6) Medial rotation - anterior fibres of gluteus medius and minimus and tensor fascia latae

Question 6

Clinical relevance: dislocation of the hip joint

Answer 6

1) Congenital dislocation - occurs as a result of the development dysplasia of the hip (DDH). Occurs when the acetabulum is shallow and as a result of failure in development in utero.
- Limited abduction at the hip
- Limb length discrepancy
- Assymetrical gluteal or thigh skin folds

DDH is treated with a Pavlik harness - it holds the femoral head in the acetabulum. Otherwise, it is indicated by surgery.

2) Acquired dislocation - relatively uncommon due to the strength and stability of the joint. Occurs as a result of trauma or as a complication of surgery.

Types of dislocation

i) Posterior - head is forced posteriorly and tears the inferior and posterior capsule. Limb becomes shortened and medially rotated. Sciatic nerve is at risk of injury (10-20%) - this is often associated in anterior femoral head and posterior wall fractures.
ii) Anterior - occurs as a result of traumatic extension, abduction and lateral rotation. The femoral head is displaced anteriorly.