Session 3 ILOs - The Lower Limb 1

Question 1

Describe the factors that stabilise the hip joint

Answer 1

• Labrum (fibrocartilagenous rim)
• Transverse acetabular ligament strengthens inferior portion of acetabulum
• Joint capsule ligaments (iliofemoral, pubofemoral and ischiofemormal)
• Ligamentum teres

Question 2

Describe the blood supply of the head of the femur

Answer 2

Blood supply comes from the deep femoral arteries which split into the lateral and medial circumflex femoral arteries

The medial circumflex femoral artery is the main source of blood supply (with reticular anterior which go back on themselves to supply the femur head)

Minor source of blood supply in the adult comes from artery of the ligaments teres = brach of obturator artery

Question 3

Indicate the safe sites for intramuscular injection in the gluteal region

Answer 3

2 regions for injection site: dorsogluteal and ventrogluteal regions

Dorsogluteal (rarely used, children 3-7):
- Draw 2 lines and inject into right upper quadrant

Ventrogluteal (most common, ages above 7 and adults):

• Make a high 5 hand with last 3 fingers together
• Inject between the index and middle fingers in line with the knuckles

Question 4

Describe the pathology of osteoarthritis

Answer 4

Osteoarthritis is an acquired condition that is correlated with age and is more common in women compared to men (primary OA = idiopathic, secondary OA = obesity, trauma etc.)

• Mechanical wearing down of articular cartilage on surface of articulating joints
• Causes increased proteoglycan synthesis by chondrocytes which is an attempt to repair cartilage
• Flaking of articular cartilage
• Leads to destruction of cartilage between bones and a consequent reduction in joint space

Altered joint mechanics leads to:

• Vascular invasion
• Increased cellularity of bone under cartilage
• Bone cysts under cartilage (from cystic degradation)
• Osteophytes form

Question 5

Describe the risk factors for osteoarthritis of the hip and the symptoms described by patients

Answer 5

Risk factors:

• Obesity
• Trauma
• Infection
• Inflammatory arthritis
• Metabolic disorders affecting the joints
• Malignancies

Patient symptoms:

• Joint stiffness that occurs upon getting out of bed
• Joint stiffness after sitting for a long time
• Pain, swelling or tenderness around the joint
• Crepitus (crunching bone)
• Reduced ROM

Question 6

Describe the features of osteoarthritis of the hip on plain X-rays

Answer 6

• Very reduced joint space
• White areas of sclerosis (hardening of the bone)
• Black areas of bone cysts

Question 7

Describe the common fractures of the hip and femoral shaft, their radiological appearance, and their complications with regard to adjacent anatomical
structures

Answer 7

Most common fracture site are at the trochanteric region and the femoral neck.

Fractures can be intracasular or extra capsular and displaced or non-displaced

Symptoms: reduced mobility, inability to bear weight and pain which may be felt in the hip groin or knee

Affected side leg in shortened and externally rotated - due to the gluteus medius and minimus, piriformis, rectus femoris and adductor magnus

Wait for answer on discussion board!

Question 8

Describe the mechanism underlying avascular necrosis of the hip following an intracapsular fracture of the femoral neck

Answer 8

For a fracture across the intracapsular fracture, the blood supply travels in a retrograde direction via the capsule from the medial circumflex femoral artery.

Any fracture within the capsule could likely damage this blood supply and result in no blood supply to the head of the femur in an adult leading to necrosis

Question 9

Describe the common mechanisms of traumatic dislocation of the hip, and the typical clinical appearance, relating the rotation and shortening of the limb to the function of the muscles

Answer 9

3 types of hip dislocations - anterior, posterior and central

1. Posterior (most common)
   = affected side leg is shortened and internally rotated
   - Can because sciatic nerve palsy in up to 20% of cases
   - Caused by high impact injury
2. Anterior (only 10% of cases)
   = affected side leg is shortened and externally rotated
3. Central (always associated with a fracture)
   - Where the femur is driven into the pelvis
   - High risk of intrapelvic haemorrhage

Wait for answer on discussion board!

Question 10

Describe the consequences of damage to the superior gluteal nerve

Answer 10

Damage to the superior gluteal nerve results in paralysis of the gluteus medius muscle (hip abductor)

Results in a characteristic gait on walking and standing known as the Trendelenburg gait
- Pelvis droops on the undamaged side (i.e. if nerve damaged on the left, the right hip would droop)