Chapter 6- Musculoskeletal Imaging

Question 1

What is the rule of twos for X-rays

Answer 1

Two views 
Two sides 
Two joints
Two times 
Two options when in doubt

Question 2

When assessing soft tissue on X-ray- what can you look for

Answer 2

• swelling
• calcification
• opacities
• gas or foreign bodies may be present
• where do they appear to be
• note degree of penetration- dark film is over penetrated and will not show good soft tissue detail

Question 3

When assessing bone on X-ray what are you looking at

Answer 3

• alignment
• structure/ gross anatomy
• radiolucent lines
• bone texture or internal architecture normal?
• cortex
• medulla
• bone density

Question 4

On X-ray of the joints what does the articular space reflect

Answer 4

Reflects the state of the articular cartilage

Question 5

When assessing the joints on X-ray, what should one look for?

Answer 5

• articulation surfaces normal shape
• if deformed are they congruous
• is there dislocation or subluxation
• is the articular space normal
• is the sunchondral bone sclerotic, cystic or porotic
• periarticular erosions or osteophytes

Question 6

Bone lesions can be defined as sclerotic, lytic or cyst like. If cyst like, what may it contain?

Answer 6

Empty- fluid
Amorphous/ ground glass
Calcification- endochondroma

Question 7

How does one describe the margins of bone lesions and what do they imply?

Answer 7

• well defined and demarcated= beneign
• infiltrative and lytic= malignant
• sclerotic = reactive / infective
• confined to bone/ extending to soft tissues
• is there a periosteal reaction

Question 8

What injuries are CTs useful in?

Answer 8

• Spinal and articular pathology and injury
• 3D reconstructions give valuable insight into fracture configurations
• CT guided procedures such as needle biopsies are essential in areas difficult to access/ open procedures hazardous

Question 9

Which injuries are well suited to ultrasound imaging

Answer 9

• tendon ruptures
• chronic overuse type injuries
• fluid collections such as a haematoma can be differentiated from generalized soft tissue oedema

Question 10

How does a bone scan work?

Answer 10

• introduction of radioactive substance, usually technetium 99
• concentrates in areas of increased metabolic activity and blood flow like infection and vascular tumors, causing a hot spot
• may be excluded in areas of decreased blood flow ( cold spot) like avascular necrosis of femur or some tumors

Question 11

When is fluoroscopy used?

Answer 11

• real time screening of bone images useful for accurate placement of internal fixation
• assessing the position of fracture fragments during manipulation
• bone biopsies

Question 12

When is MRI used in orthopaedics

Answer 12

• imaging soft tissues, especially neural tissue (spinal cord and roots) and tumours
• bone bruising or oedema and aseptic bone necrosis can be well demonstrated