Principles of MSK Radiology Flashcards
Label regions on Xray of long bone (arm)
Lecture Slide
Ossification centers and sesamoid bones
- Adult vs child carpal bones
With growth bones develop and ossify and become radiopaque. The sequence of appearance of radiopaque ossification centers can be used as a measure of bone age of a child.
What are sesamoid bones and example
Sesamoid bones are bones that are embedded in tendons.
Patella
MSK radiograph:
ABC’S stand for?
A – Alignment
B – Bones
C – Cartilage
S – Soft tissues
Alignment questions
- Are the bones aligned with associated
joints?
2.Are the two (or more) joint surfaces
aligned with each other.
->If only partially aligned the joint is
subluxed.
-> If no alignment joint is dislocated.
When there is trauma whats essential to show full trauma
Long bone X-rays should include what
In trauma it is essential that at least two views are taken at 90 degrees to each other to fully appreciate the displacement.
Also x-rays of the long bones should always include the joint at both ends to assess joint involvement and any rotation.
Bones:
What questions to ask
- Check the shape of the bones, and for local expansion or thinning.
- Check the cortical continuity (appear as line), as a step or break in the cortex could indicate a fracture.
- If there are unfused epiphyses, is the bone development and ossification age appropriate?
- Check the texture of the Bone. Is it sclerotic (MORE DENSE) or lucent (LESS DENSE)?
- Is the texture uniform or are there regions of abnormality that may indicate tumor
or infection?
Cartiliage:
Check the joint space for:
Check the joint space for:
- Increased Joint space – seen in infection, inflammation, trauma, and tumor
- Decreased joint space – seen in degenerative and inflammatory joint disease
- Calcification in joint (chondrocalcinosis) - seen in crystal arthropathies, trauma,
osteoarthritis, hyperparathyroidism, haemochromatosis.
*** CARTILIAGE IS NOT LUCENT, SHOULD BE EVEN COLOURATION)
Soft tissues
Check the surrounding soft tissues for:
- Masses (can be calcified) ,
- Gas seen in infection and trauma
- Foreign body
- Joint effusion with or with out a blood/lipid fluid level as can be found in trauma
- Fat pad sign due to displacement of normal tissues by a fluid distended joint. Useful
at the ankle joint and elbow joint.
Describing a fracture checklist:
- Right or left side
- Bone or bones involved. Is there more than one fracture?
-> For each bone how may bone fragments. If two = simple fracture, if > two = Commminuted - Is the injury open or closed? (Bone sticking out of skin) If it communicates with the outside bacteria can get in.
- Does fracture line involve the joint? In so intra-articular (verses extra articular)
- The position of the fracture diaphyseal, metaphyseal, distal 1/3 etc
- The direction – transverse, oblique, spiral?
- The relationship of the fragments to each other. When this is done the convention is to describe the relationship of the distal bone fragment relative to the proximal fragment.
- Describe how much the distal fragment is displaced ventro-dorsally and side-to-side FROM the proximal fragment (fragment nearer the body core anatomically).
- Describe if there is any overlap of the ends of the fracture and how much by
- Describe if there is any angulation. Again, this will be the degree the distal fragment is displaced relative to the proximal fragment when in the anatomical position (see lecture one). It could be anterior, posterior, lateral or medial displacement.
- Describe if there is any rotation of the distal fragment.
Bone texture:
Describe osteopenia texture on plain film
and causes
Reduced bone density
It can be secondary to hormonal, dietary, biochemical and physical influences such as disuse, diseases such as hyperparathyroidism, rickets, and due to drugs such as Prednisone.
On plain-film radiography the bones appear more lucent, cortex is thinned, and bone trabeculae are sparse.
Focal lucent lesion(s) (osteoblastic) in bone
Cause
crtierira for being detected on xray
often due to bone metastases or a primary bone tumor, inflammatory joint disease, or osteomyelitis.
For a lesion to be detectible on an x-ray ~50% of the bone will need to have been lost. Osteopenic bones are prone to fracture, e,g. neck of femur and vertebrae.
Focal lesions (in a single, localised place) with increase in bone density (osteoblastic) can also be due to metastases.
Generalized increase in bone density usually has specific patterns of changes in bone texture such as in Paget’s disease or osteopetrosis.
Common joint diseases in NZ
Osteoarthritis
Rheumatoid artiritis
Gout
Osteoarthritis:
Causes
Sites typically found at
Radiology signs
Repetitive trauma or “wear and tear” often results in osteoarthritis. Acute trauma involving a joint also predisposes to osteoarthritis.
This usually affect large joints (eg hip, shoulder), and can involve tendon/ligament failure (e.g. rotator cuff tear ).
Radiologically the joint space is reduced, bone spurs may develop as may soft tissue swelling.
Rheumatoid arthritis:
Where does it start and progress to?
Features on radiograph
This is a systemic disease that primarily manifests in the smaller joints first – fingers, toes, then wrists, knees, ankles, elbows, hips, shoulders. It is usually symmetrical.
The inflammation destroys the cartilage and bone, reducing the joint space and creating typical bone erosions seen on radiographs. The inflammation thickens the synovium.
Tendons and ligaments weaken and stretch, and the joint loses its shape and alignment.
Gout:
Cause
signs of acute gout
chronic gout progression
Radiography features
Deposition of monosodium
urate crystals in and around the joints. In acute gout there
is a monoarticular red, inflamed, swollen joint. It often affects the first
metatarsophalangeal joint. May develop into chronic
tophaceous gout.
Solid urate crystal collections (tophi) and
chronic inflammatory and destructive changes occur in
the joint and surrounding
connective tissue.
Radiologically Punched-out lytic bone lesions with overhanging sclerotic margins. Periarticular soft tissue swelling due to crystal deposition in tophi around the joints. Soft tissue swelling may be hyperdense due to the crystals.
Plain radiographs
Advantages and Disadvantages
Advantages
- Excellent initial for examination of bone and bone texture
- Inexpensive
- Readily available
Disadvantages
- Poor for visualization of soft tissues and non-bony component of joints
- Can use contrast (injected into joint) for arthrography but invasive procedure
- 2D only
– need to take orthogonal views
- Ionizing radiation dose to patient but low (0.1 mSv
– which corresponds to 10 days
‘natural’ background radiation)
CT Scan
Advantages vs Disadvantages
Advantages
- Excellent for examination of bone and bone texture
- 3D reconstruction available
– useful for surgical planning and examination of complex fractures
- Moderate visualization of soft tissues and non-bony component of joints without the use of contrast agent
- Readily available
- Can use with contrast agent to enhance soft tissues
Disadvantages
- Large ionizing radiation dose to patient 10 mSv, or
the equivalent of 3 years ‘background’ radiation
Magnetic resonance imaging (MRI)
Advantages vs Disadvantages
Advantages
- Excellent for examination of soft tissue and joints
- Can be used to identify un-displaced fractures/bone edema - Multiplanar acquisition
– useful for surgical
planning
- Can use with contrast agent to enhance soft tissues
- No ionizing radiation
Disadvantages
- Expensive
- Not readily available
- Some people with metal implants cannot be examined
- Can be claustrophobic
- Long scan time and patient needs to keep still
- Children may require general anesthetic
Ultrasound
Advantages vs Disadvantages
Advantages
- Excellent for examination of soft tissue and some joints (penetration limited)
- Low cost
- No ionizing radiation
- Can use with contrast agent to enhance soft tissues
– sometimes
- Multiplanar acquisition–sometimes
- Inexpensive
- Readily available
- Can be used to guide procedures in real time such as hip aspiration
Disadvantages
- Operator dependent
- Cannot penetrate bone or air
Technetium 99 Bone scan
Advantages (uses) vs Disadvantages
Advantages
- Used to identify metabolically active bone
- occult fractures
- infections
- malignancy
- High sensitivity
Disadvantages
- Ionizing radiation dose between X-ray and CT scan @~
3 mSv (37 mSv for cancer staging)
- Limited use for soft tissues
- 2D
- Poor specificity
- Moderately expensive
- Not readily available
when does visible ossification centres apepar
between 1 month and 12 years
One way to differienate sesamoid bone vs fracture
one way to tell it’s a sesamoid bone is cortex looks complete or round
Describe these fractures:
Smith Fracture:
Colles Fracture
Extra-articular Smith’s fracture with palmar
and radial angulation and displacement.
There is also an avulsion of the ulnar styloid process
Left sided comminuted-intra-articular fracture of distal radial metaphasis with radial shortening and 15 degrees dorsal angulation
When does it become lumbar vertebrae and not thoraic
When it vert doesnt have a rib attached = lumbar
