Radiology Of Arthritis Flashcards
List the most common imaging modalities and what are they for?
Radiographs - basic test, trauma, arthritis, congenital, tumour
CT - bone detail, complex fractures
Ultrasound - small superficial lumps, tendons, joints, ligaments and synovitis
Nuclear medicine and PET scanning - cancer staging
MRI - gold standard for assessing diseases of joints, soft tissue and bones
DEXA scanning - osteoporosis
Guided interventional procedures - CT or US guided biopsy, drainage and radio-frequency ablation
Describe the different densities on X-Ray.
Bone - white
Air - black
Fat - dark grey
Water (muscle) - grey
Why is it important to take an X-Ray in more than view?
An injury may be obscured or not visible from a certain angle
- e.g. Patella fracture can not be seen in an AP/PA view, but it can be seen in a lateral view
Name some different fracture descriptions.
Displaced - the two bone edges don’t match up
Angulated - the distal bone isn’t lying flush with the proximal bone
Rotated - the distal bone is twisted
Overriding - the slipping of either part of the fractured bone past the other
Distracted - widening of the gap between the two pieces of fractured bone
Comminuted - a break of splinter in the bone of more than two fragments
Compound - when the broken bone pierces the skin
What is the difference between extra and intra articular fractures?
Intra-articular fractures involve the joint space
- these are more serious as they affect the movement of the joint
Extra-articular fractures occur out of the joint space
What are the complications of a supracondylar fracture?
Malunion results in ‘gunstock’ deformity due to rotation or inadequate correction of medial collapse
Posterolateral displacement of the distal fragment can damage the neurovascular bundle
- results in neuropraxis that resolves after 3-4 months
- vascular injury results in pulssless, pink hand
Why is fracture of the femoral neck serious?
Because the blood supply to the head of the femur, passes through the femoral neck
- can cause an avascular crumbling head
What are the different kind of fractures that can occur around the femoral head?
Subcapital neck fracture Transcervical neck fracture Intertrochanteric fracture Subtrochanteric fracture Fracture of the greater trochanter Fracture of the lesser trochanter
Describe Paget’s disease of the bone.
Increased bone turnover - osteoclastic and osteoblastic activity
Can be monostotic or polyostotic
Raised alkaline phosphatase
Complications include fractures, deformities and (rarely) sarcomas
Describe the blade of grass sign seen in Paget’s disease.
The lucent leading edge of bone seen during the lytic phase of Paget’s disease.
What are the radiological hallmarks of degenerative, inflammatory and depositional arthritis?
Degenerative - bone production (sclerosis)
Inflammatory - periarticular erosions
Depositional - periarticular soft tissue masses (e.g. Gout)
Describe the radiological changes seen in reactive bone formation.
Sub-chondral sclerosis
Osteophytosis
Periostitis - inflammation of the periosteum
Describe the radiological signs of bone erosion.
Location
- peri-articular (occurs at the edge of the joint where the capsule inserts)
- para-articular (near the joint)
Appearance
- if the erosion is ill-defined, the disease is active
- if it is well-defined, the disease is old
Gout erodes further from the joint that RA does
What is the difference in RA and OA regarding the pattern of affected joints?
RA - MCP, wrist and PIP joints mainly
OA - DIP and PIP joints mainly
If an inflammatory cause of arthritis is suspected, how can you tell if it is an infection or not?
Infections typically only affect on joint at a time
- e.g. RA is a symmetrical polyarthropathy
