Hip Disorders

Question 1

Osteoarthritis pathology

Answer 1

Excessive loading of joint
= Breakdown of articular cartilage
Increased proteoglycan from chondrocytes to try and repair
Flaking and fibrillation of cartilage (replaced by fibro)
Erosion of cartilage

Question 2

Primary osteoarthritis causes and risk factors

Answer 2

Cause unknown
Risk factors:
Age
sex (female > male)
Ethnicity 
Nutrition
Genetics

Question 3

Secondary osteoarthritis causes (8)

Answer 3

Causes:
Obesity 
Trauma (sports)
Malalignment - developmental dysplasia 
Infection
Inflammatory conditions
Metabolic disorders (gout)
Haematological disorders 
Endocrine abnormalities

Question 4

What does osteoarthritis lead to?

Answer 4

Question 5

Symptoms of osteoarthritis in any joint (3)

Answer 5

• A deep aching joint pain, exacerbated by use
• Reduced range of motion and crepitus (grinding)
• Stiffness during rest (morning stiffness, usually lasting < 1 hour)

Question 6

How is OA diagnosed?

Answer 6

Clinical signs and symptoms + Xray to confirm

Question 7

Management osteoarthritis (no op)

Answer 7

Activity modification
Weight loss
Walking stick/frame
Physiotherapy/muscule-strenthening exercises
Orthotic footwear

Question 8

Medications for OA

Answer 8

• Analgesia (e.g. paracetamol)
• Anti-inflammatories (NSAIDs, COX-2 inhibitors)
• Nutritional supplements e.g. glucosamine and chondroitin sulfate.

Injections:
- Steroid injections can be performed into the joint to reduce swelling and thereby alleviate shoulder stiffness and pain.
- Hyaluronic acid injections into the joint (viscosupplementation) may increase lubrication and possibly promote cartilage repair, although the evidence for this is limited.

Question 9

Surgical procedures for OA
What does it do?

Answer 9

Total Hip replacement -replaces the damaged surfaces with implants and helps to relieve pain and restore mobility.

(metal ball and socket joint down femur)

Question 10

Types of femoral fractures

Answer 10

Intracapsular - neck of femur (above intertrochanteric line)

Extracapsular - below intertrochanteric line

Question 11

Blood supply effects femoral fractures

Answer 11

• In intracapsullar fractures, there is a high risk of avascular necrosis of the bone.
• This is because intracapsular fractures are likely to disrupt the ascending cervical (retinacular) branches of the medial femoral circumflex artery (MFCA).
• Due to the inability of the Artery of the Ligamentum Teres to sustain the metabolic demand of the femoral head, there is a high risk of avascular necrosis of the bone.
• This risk is increased if the fracture is displaced.
• With extracapsular fractures, the retinacular arterial supply to the femoral head is likely to remain intact.

Question 12

Symptoms/signs of femoral fracture

What are the symptoms of Fractured neck of femur? (2)

What does the doctor find on examination if the fracture is displaced?

Answer 12

• Reduced mobility / sudden inability to bear weight on the limb
• Pain which may be felt in the hip, groin and/or knee
• On examination, if the fracture is displaced, the affected leg is usually shortened, abducted, and externally rotated. There is exacerbation of pain on palpation of the greater trochanter and pain is exacerbated by rotation of the hip.

Question 13

Why do legs externally rotate in NOF fracture?

Answer 13

• The axis of rotation of the femur that normally passes obliquely through the head and down the neck of the femur, shifts to pass through the greater trochanter and vertically down the long axis of the femoral shaft.
• The short lateral rotators of the hip (piriformis, obturator internus, superior and inferior gemelli and quadratus femoris) contract and laterally (externally) rotate the femoral shaft.
• The iliopsoas also now acts as a lateral rotator of the femur as it pulls the lesser trochanter anteriorly about the new axis of rotation, so the femoral shaft rotates externally.

Question 14

Types of Surgery for hip fracture

Answer 14

Hemiarthroplasty (femoral head replaced)

Total hip replacement (femoral head and acetabulum replaced)

Question 15

Causes of avascular necrosis (6)

Answer 15

Mechanical disruption (fracture)
Alcoholism
Steroid use
Post trauma
Thrombosis 
Hypertension

Question 16

Most common type of hip dislocation

Answer 16

90% posterior

Question 17

Types of people intracapsular and extracapsular occur in

Answer 17

Intracapsular - mostly elderly, post menopausal women with osteoporotic bone after a minor fall

Extracapsular - young/middle aged after a significant trauma force (road traffic accident/rugby)

Question 18

Signs of posterior hip dislocation (5)

Answer 18

Shortening
Flexion
Adduction 
Internal (medial) rotation 
Sciatic nerve palsy (foot drop) can occur

Question 19

Why does shortening and internal rotation occur after posterior dislocation?

Answer 19

• The femoral head is pushed backwards over the posterior margin of the acetabulum and comes to lie on the lateral surface of the ilium.
• The head of the femur is then pulled upwards by the strong extensors (gluteus maximus and hamstrings) and adductors of the hip, causing limb shortening.
• The anterior fibres of the gluteus medius and minimus pull on the posteriorly- displaced greater trochanter and cause the femur to rotate internally.

Question 20

Anterior hip dislocation (4)

Answer 20

• External rotation
• Abduction
• Slight flexion

Femoral nerve palsy can be present but uncommon

Question 21

Central dislocation

Answer 21

• In central dislocation, the head of the femur is driven into the pelvis through the acetabulum. It is always a fracture-dislocation.
• The femoral head is palpable on rectal examination and there is a high risk of intrapelvic haemorrhage due to disruption of the pelvic venous plexuses.
• This can be a life-threatening injury.