MSK 7 - Hip Joint Disorders

Question 1

What are the 2 main blood supplies to the femoral head?

Which of these are more important in children + adults?

Answer 1

1) Artery of ligamentum teres - most important in children, contribution decreases with age.
2) Ascending cervical branches (from deep femoral artery) - Arising from base of the neck - highly susceptible to injury w/hip dislocation.

Question 2

What are the 2 classifications of osteoarthritis and their causes?
What are the common risk factors for OA?

Answer 2

1) Primary = unknown cause
2) Secondary = causes include obesity, trauma, infection, inflammatory arthritis, endocrine abnormalities etc.

Risk factors = Age, sex (female>male), ethnicity, nutrition and genetics (OA can run in families).

Question 3

Describe the pathological process and consequences of OA.

Answer 3

• Precipitating risk factors (e.g.: obesity) leads to excessive loading of joint and damage to articular cartilage.
• Increased proteoglycan synthesis by chondrocytes as an initial attempt to repair cartilage.
• Get flaking/fibrillation of articular cartilage + erosion of cartilage down to subchondral bone and thus a reduced joint space.
• Consequences include roughening of bone, bone spur growth (osteophytes), narrowed joint space, worn cartilage etc.

Question 4

What are the radiological features of hip OA?
What are the symptoms of hip OA?
What is Trendelenburg’s sign?

Answer 4

• No joint space, cysts in bone of femur head, sclerosis/hardening of bone (appearing more white).
• Joint stiffness getting out of bed/sitting for long time. Pain, swelling + tenderness of hip joint, Crepitus (crunching sound of bone against bone), reduced ability to perform routine activities, e.g.: putting socks on.
• Trendelenburg sign - pelvis droops on unaffected side, while standing/weight bearing on affected leg/hip. Due to OA or superior gluteal nerve damage

Question 5

What is the treatment overview of OA increasing from mild to severe symptoms?

Answer 5

Mild = education, exercise adjustment, weight loss, appropriate footwear + other non-pharmacological management, e.g: physiotherapy, walking sticks + braces.

Medium = pharmacological management, e.g.: NSAID’s (ibuprofen), COX-2 inhibitors (celecoxib), corticosteroid injections (reduce inflammation) + supplements (e.g.: hyaluronic acid).

Severe = Surgery, e.g.: osteotomy + total hip joint replacement (to restore mobility + reduce pain)

Question 6

Where do the majority of hip fractures occur?

What is the significance of this?

Answer 6

• In the neck and intertrochanteric region.

- If displacement fractures occur in the neck, blood supply to hip joint is compromised, and management differs.

Question 7

What are the % consequences of hip fractures 1 year after fractures?

Answer 7

• 80% unable to carry out at least 1 independent activity of daily living
• 40% unable to walk independently
• 30% permanent disability
• 20% dead within 1 year

Question 8

What are the symptoms + key clinical signs of a hip fracture?

Answer 8

• Reduced mobility/inability to bear weight on that side. Pain may be felt in hip, groin and/or knee.
• A shortened + externally rotated leg. Shortening due to rectus femoris + adductor magnus, external rotation due to gluteus + piriformis.

Question 9

What are the 2 main types of hip fractures?

What does an intracapsular hip fracture leave a high risk of?

Answer 9

• Intracapsular (through the neck, blood supply likely compromised) + extra-capsular.
• Intracapsular leave high risk of avascular necrosis (AVN), where blood supply to femoral head is compromised, causing necrosis of bone and death of part of the femoral head. (see femoral head is no longer rounded on images).

Question 10

What are some potential other causes (apart from hip fracture) of avascular necrosis?

Answer 10

• Alcoholism, excessive steroid use, thrombosis, hypertension.

Question 11

What are the 3 main types of hip dislocation and the clinical signs of each?
Which types are the most/least common?

Answer 11

1) Posterior (90%) - hip comes out the back - see shortened gluteus maximum + hamstrings + internally rotated leg that is flexed.
2) Anterior - hip comes out the front - see externally rotated, abducted, slightly flexed leg.
3) Central - head of femur pushes through socket - always a fracture dislocation, femoral head palpable per rectum, significant blood loss (intrapelvic haemorrhage)

Question 12

What are the potential complications of hip dislocations?

Answer 12

• Avascular necrosis (1-20%)
• Post-traumatic OA
• Recurrent dislocation
• Sciatic nerve injury/foot drop (20% adults)
• Infection