Radiology Flashcards
signs suggesting OA
asymmetrical joint involvement
weight bearing/active joints
what is seen on an x-ray in OA
Loss of joint space
Osteophytes
Subchondral cysts
Subchondral sclerosis
what causes a loss of joint space in OA
asymmetric cartilage wear
weakened bones caves
what causes subchondral sclerosis in OA
increased subchondral bone cellularity and vascularity excites bone turnover
what causes subchondral cysts in OA
synovial fluid dissects into bone
what causes osteophyte formation in OA
periosteal stimulation
signs suggesting RA
symmetrical joint involvement
affects synovial joints
commonly - MCP, MTP, PIP, C1/2 (atlantoaxial joint), wrist/hip/knee/shoulder
what joint in the hands are not affected by RA
DIP
radiographic features of RA
LESS Lost of joint space (joint subluxation) Erosions (Destruction of bone at joint margins) Soft tissue swelling Soft bones (osteopenia)
what causes soft tissue in RA
synovial proliferation and reactive joint effusion
what cause periarticular osteoporosis in RA
Hyperaemia causing bone demineralisation resulting
what causes destruction of bone in RA
inflammatory pannus
what causes joint subluxation/deformity
capsular and ligamentous softening
what fuses in RA
Exposed eroded bone ends may fuse (ankylosis)
features of seronegative arthritis
Sacroiliac joint and spine involvement
Ill-defined periarticular bone formation
Tendency to joint ankylosis
psoriatic arthritis joint distribution
small joints of hands and feet
DIP joints, IP joint great toe
AS joint distribution
scattered lower limb large joints
reactive arthritis distribution
scattered lower limb large joints
lower limb entheses
why are x-rays not often used to diagnose arthritis
can only see late stage damage
should be prevented
other lab tests first line
how can increased vascularity around joints be seen
isotope bone scan
what can a Doppler US show in arthritis
Thickening of synovium and increased blood flow
what do each Ix show
x-ray - bone but no soft tissues
CT - bone in more detail and some soft tissue
MRI - bone in less detail and all soft tissues
which vertebra has no body and what is it called
C1
Atlas
when is CT used to image spinal trauma
X-ray shows # but
- more detail required
- any more fractures present ?
X-ray normal but
high clinical suspicion of #
what tether vertebrae together are are responsible for spinal stability
intervertebral ligaments
are ligaments seen on x-ray or CT
no
but seeing normal alignment on test test implies intact ligaments and a stable spine
how do ligaments appear on MRI
normal - black
damaged - light
when is MRI used in spinal trauma
To provide detail of the spinal ligaments
In patients with neurological deficit, which is not explained by x-ray or CT, to show soft tissue abnormality, such as:
acute prolapsed intervertebral disc
epidural haematoma
spinal cord damage
pathogenesis of intervertebral disc disease
- discs dehydrated as a prelude to disease
- disc material herniates through disc lining into spinal canal
- press on spinal nerve
- sciatica
what imaging is used for intervertebral disc disease
CT and MRI
MRI is best showing early disc dehydration preceding herniation
what Ix is used to see spinal cord
MRI
principles of imagine
- Clinical features are there to help you
- One view is rarely enough
- Fracture appearance is variable
- Always assess bony alignment
- Check for soft tissue abnormality
- Children can sustain a unique set of injuries
- Don’t switch off after finding one abnormality
- Only dense foreign bodies are shown by x-rays
features of Hx/Ex that help guide x-ray interpretation
- MOI
- site of bone tenderness
- presence of deformity
- patient age
** views for cervical spine
AP
Lateral
Odontoid peg
** views for scaphoid
AP
Lateral
Two obliques
what are avulsion fracture mimics
sesamoid bone
accessory ossification centres
old non-united fracture
what is the posterior fat pad sign
elbow effusion most commonly caused by trauma
displaced fat pad visible posterior to distal humerus
is seeing the posterior fat pad sign normal
no it is always abnormal
sensitive indicator of elbow trauma
why do children sustain a unique set of injuries
bones are soft
they ‘bend or bow’ rather than ‘snap and splinter’
fractures are often incomplete
what is a buckle fracture
incomplete fractures of the shaft of a long bone with a bulging of the cortex
often distal radial metaphysis
what is a greenstick fracture
incomplete fractures of long bones
commonly mid-diaphysial affecting forearm and lower leg
what is common in fractures in children
common for ligaments or tendons to avulse their soft bony attachments.
what can mimic a fracture in children
the growth plate/physis
where is the weakest part of the bone in children
the growth plate - prone ton injury
what is used to classify growth plate fractures
Salter-Harris
why would injury of femur in a baby be suspicious
isn’t rolling/walking
NAI suspected
where are examples of bony rings in the body
spinal canal
pelvis
forearm and lower leg
what should be suspected in a bony ring with a fracture
that there is more than 1 fracture
what foreign bodies can be seen on x-ray
metal + glass
Plastic and wood cannot be seen
when should a pathological fracture be suspected
when bone abnormality seems out of proportion to the mechanism of injury
Colles fracture
elderly with osteoporosis
dorsal angulation of radius
associated ulnar styloid #
radial buckle fracture
children with soft bones
scaphoid fracture
young males
pain in anatomical snuffbox
commonly mid-scaphoid (waist)
surgical neck humerus fracture
post-menopausal females
sclerosis indicates impaction
often comminuted
can damage axillary nerve
what should be obtain in posterior shoulder dislocation
oblique view
what can supracondylar fractures damage
brachial artery
complications of scaphoid fracture
proximal scaphoid blood supply can be disrupted by a fracture, making it prone to non-union (on right) or avascular necrosis leading to early wrist osteoarthritis
what is Bennett’s fracture
fracture of the base of the first metacarpal bone (thumb) which extends into the carpometacarpal (CMC) joint
why do lower limb fractures have higher morbidity and mortality
Immobility through lower limb injury may lead to:
dehydration and starvation
DVT or pulmonary embolus
pneumonia
pelvic ring fracture - high energy
young people
RTA or fall from height
usually multiple fractures
what is the Ix used in polytrauma patients
CT scan
pelvic ring fracture - low trauma
affect elderly patients with osteoporosis
typically due to a minor fall, may be of insidious onset
MRI test of choice (invisible on x-ray)
what is used to show acute injuries affecting superficial structures
USS
sports related pelvic injuries
acute hamstring tendon avulsion hip dislocation (can also be due to RTA)
hip dislocation
CT - detailes fracture anatomy to assist surgical planning
can have femoral head AVN or early OA
useful fracture classification
intra vs extra capsular
features of intra-capsular fractures
interfere with blood supply to femoral head prone to femoral head AVN or non-union
Tx of intra-capsular fractures
treated by hemiarthroplasty, unless undisplaced or young patient when reduction and screw fixation may be tried
features of extra-capsular fractures
don’t affect blood supply to femoral head
don’t get femoral head AVN or non-union
Tx of extra-capsular fractures
internal fixation using DHS
when should an x-ray be repeated if a fracture is suspected
10 days after
femoral shaft fractures
usually high energy
risk of blood loss, fat embolus
fractures of knee
X-ray initially
CT - clarify fracture anatomy
US + MRI - assess soft tissues
what does significant soft tissue injury in the knee cause
effusion in the supra patellar space
lipohaemarthrosis (blood and fat collecting)
standard trauma imaging of the knee
X-ray - AP, lateral
tibial plateau fracture
lateral condyle
follows valgus force with foot planted ‘bumper injury’
well shown by CT
Ix for extensor mechanism injury
US
common test in acute knee trauma and why
MRI
Can show things hidden by swelling
What is MRI an Ix for
Ligament tear
Hyaline cartilage injury
Meniscal tears
Undisplaced fractures
what does hyaline cartilage damage predisposes to
early OA
what does the tibia and fibula form
bony ring
injuries usually involve > 1 site
Ix for ankle injuries
clinical examination
x-ray - AP and lateral
what is a pilon fracture
fracture of the distal part of the tibia, involving its articular surface at the ankle joint
what are used for complex ankle fractures
CT scan
what is talar dome margin fractures
injury to the cartilage and underlying bone of the talus within the ankle joint
5th metatarsal bone fracture
follows inversion and clinically resembles a lateral malleolar #, so check this area on the lateral x-ray
are transverse
Calcaneal fracture
axial compression (falling from height onto the hell) causes loss of the park and increased bone density
how is the normal calcaneus central peak measured
using Bohler’s angle
where are accessory ossification centres seen
5th metatarsal - in teens
posterior calcaneus - in children
os trigonum
sesamoid bone
fabella - within lateral head of gastrocnemius
rounded sesamoid bone seen in the foot
medial and lateral plantar aspects of 1st metatarsal head
what predispose tendon rupture
diabetes
RA
Steroid use
Ix for tendon rupture
US - allows dynamic assessment
MRI - 2nd line
midfoot fracture views
AP - 1st and 2nd TMT joint
Oblique - 3rd and 5th TMT joint
