Imaging in Arthritis

Question 1

Describe distribution of OA?

Answer 1

Joint inv. is often ASYMMETRICAL

Usually affects weight-bearing or active joints, e.g: spine, hip, knee, base of the thumb, DIPs

Question 2

Causes of secondary OA?

Answer 2

Overuse

Previous injury

Previous arthritis

Question 3

Radiographic features of OA?

Answer 3

Loss of joint space (due to asymmetric cartilage wear)

Osteophytes (periosteal stimulation leads to MARGINAL osteophyte formation, which tend to be pointy)

Subchondral sclerosis (increase in white areas, as bone responds to trauma by laying down new bone)

Subchondral cysts (synovial fluid dissects into bone)

Joint deformity (weakened bone caves in)

Question 4

Disease distribution of RA?

Answer 4

Joint inv. is usually SYMMETRICAL

It can affect any synovial joint, commonly:
• MCP, MTP 
• PIP (but NOT DIPs)
• Wrists, hips, knees and shoulders
• Atlanto-axial joint (C1/2)

Question 5

Radiographic features of RA?

Answer 5

Synovial proliferation and reactive joint effusion cause SOFT TISSUE SWELLING

Hyperaemia causes bone demineralisation, resulting in PERIARTICULAR OSTEOPOROSIS (increased blackness)

Inflammatory pannus destroys bone, initially at joint MARGINS but this progresses to THROUGHOUT the joint

Capsular and ligamentous softening allow joint SUBLUXATION and DEFORMITY

Exposed eroded bone ends may FUSE (alkylosis)

Question 6

Radiographic features of seronegative arthritis?

Answer 6

Sacro-iliac joint and spine inv.

Ill-defined peri-articular bone formation

Joint ALKYLOSIS (fusion and bamboo spine)

Question 7

Disease distribution of psoriatic arthritis?

Answer 7

Small joints of the hands and feet

DIP JOINTS ARE AFFECTED as are the IP joints of the hallux

Question 8

Disease distribution of ankylosing spondylitis?

Answer 8

Scattered lower limb large joints

Question 9

Disease distribution of Reiter’s syndrome?

Answer 9

Scattered lower limb large joints

Lower limb entheses

Question 10

Use of an isotope bone scan in arthritis?

Answer 10

Can show increased vascularity around joints, which accompanies synovitis

Question 11

Use of a colour Doppler ultrasound?

Answer 11

Can show thickening of the synovium and increased blood flow

Question 12

Use of MRI in arthritis?

Answer 12

Can show periarticular bone marrow oedema that often precedes significant joint erosion/damage, providing early evidence of inflammatory disease (allowing treatment that prevents worsening of the disease)

Can show anatomy in all planes

Question 13

Aims of imaging in arthritis?

Answer 13

Diagnosis

Monitoring of disease progression and treatment