Diagnostic Imaging: Musculoskeletal Imaging: Imaging in Lameness Flashcards
What are the indications for lameness radiographs?
- Acute or chronic lameness
- Skeletal or joint pain
- Fracture confirmation/characterisation
- Swelling centered on bones/joints
- Monitoring/screening for inherited musculoskeletal disease
- Metabolic bone disease
- Evaluation of systemic disease
How is the correct region to image determined?
- Thorough clinical exam and history
- Comprehensive orthopadeic exam
- Examination under GA/Sedation
What is geometric distortion?
- Occurs if structure is towards edge of collimated area
- Or not truly parallel to the film/detector
- Tight collimation can help
What are the limitations to lameness radiographs?
- Oblique projections can create apparent artefactual lesions
- Poor soft tissue contrast resolution
What is serial radiography used for?
- Monitor progression of disease
- Show diseases radiographically occult in their early stages
- Assess dynamic component of disease
- Can be useful if diagnosis is uncertain
What are the radiographic rontgen signs?
- Number
- Size
- Shape
- Location
- Opacity
Consider that the lesions is possibly: artefact, normal, superimposed shadow
What should be specifically assessed about bones and joints in musculoskeletal cases?
Bones
* Alignment, shape, length
* Periosteal reaction/cortical lysis/defects
* Endosteal/medullary changes
* Physes
Joints
* Swelling/effusion
* Subchondral bone
* Periarticular changes
Soft tissue
* Swelling/loss
What can cause reduced size of soft tissues?
Atrophy
* Chronic lameness
* Neurogenic
* Fibrosis/scarring
Weight loss
What can cause increased size of soft tissues?
Focally
* Trauma
* Abscess/seroma
* Granuloma
* Neoplasia
Diffuse
* Oedema
* Cellulitis/vasculitis
* Diffuse neoplasia
What can a reduction in opacity of bones mean?
- May be artefactual
- 30-60% mineral loss is required to be appreciated
- Minimum 7 days to be apparent
- Focal loss easier to detect
How can focal bone loss (lysis) be described?
- Geographic
- Moth-eaten
- Permeative
Periosteal reaction can be inactive/benign to active/aggressive
How can it be described from benign to active?
- Smooth
- Rough
- Brush border
- Pallisading
- Spicular
- Sunburst
- Amorphous
What are these different arrows labelling?
Top- Bottom
* Transition zone- long
* Periosteal reaction- active
* Cortical integrity- destruction/expansion
* Soft tissues- swelling/mass
How can distribution of skeletal lesions be categorised?
- Monostotic- one bone
- Polyostotic- multiple bones
- Focal
- Generalised
- Symmetrical
- Asymmetrical
What is critical to assess about joints?
- Soft tissue swelling
- Joint ‘space’ width
- Subchondral bone opacity
- Osteophyte/enthesophytes
- Periarticular mineralisation
What may a joint effusion not be indistinguishable from?
Joint effusion may not be distinguishable from periarticular swelling
Other then stifle- adjacent fat
What are the differentials for subchondral defects at joints?
- Osteochondrosis
- Aseptic necrosis (femoral head)
- Septic arthritis
- Erosive arthritis (carpus/tarsus)
- Soft tissue neoplasia
- Trauma (avulsions)
- Osseous cyst like lesions
- Osteoarthritis (only very severe)
What are the two following subchondral defects?
Left- erosive arthritis
Right- Avulsion fracture- pulled of origin of Cranual cruciate ligament
What presents on a radiograph with osteoarthritis?
- Soft tissue swelling/effusion
- Periarticular new bone at predictable sites
- Subchondal sclerosis
- Narrowed joint space
- Look for the primary disease process
What is the difference between an osteophyte and an enthesophyte?
Both are types of periarticular bone
* Osteophyte is in the joint capsule
* Enthesophyte is in the ligament
What do these images show?
Mineralised bodies
* Commonly seen
* Normal- sesamoids, accessory centres of ossification
What are the predilection sites for osteochondrosis?
- Caudal aspect humeral head
- Medial part humeral condyle
- Lateral femoral condyle
- Medial trochlear ridge talus
What are the predilection sites for osteosarcomas?
- Proximal humerus
- Distal radius/ulna
- Distal femur
- Proximal tibia
How can ultrasound be used to image and help diagnosis of lameness?
- Use linear (high frequency) probe
- Muscles, tendons and ligaments can be visualised clearly
- Bone surface is well depicted
What are the key soft tissue structures surrounding the shoulder that can be visualised?
- Biceps tendon and sheath (craniomedial)
- Supraspinatus and infraspinatus muscles and tendons (lateral/craniolateral)
What can be ultrasound imaged at the tarsus?
Calcaneal tendon
* Gastrocnemius
* Superficial digital flexor
* Conjoined/common calcaneal (bicep femoris, semintendinosus and gracilis)
How is the right imaging modality selected?
- Radiographs usually initially
How is an image examined?
- Correct region radiographed
- Well-positioned, reproducible
- Adequate number/orthogonal
- Free from significant artefacts
- Awareness of limitations
Label the epiphysis, diaphysis and metaphysis
Top- epiphysis
Middle- diaphysis
Bottom- metaphysis
