4&5 - trauma imaging of upper & lower limb Flashcards
what are some good basic principles for trauma imaging?
- more than 2 views needed
- check bony alignment
- check for soft tissue abnormality
- don’t stop if see 1 fracture (can be more)
what are some types of fractures?
- lucency crossing bone
- cortical extension
- spiral/transverse
- comminution
- joint involvement
- angulation
- displacement
- impaction
- avulsion
what are some acute avulsion mimics?
- sesamoid bones = multiple sites of foot, medial & lateral aspects of 1st metatarsal heads
- accessory ossification centres = seen at 5th metatarsal head or posterior calcaneus or talus in kids
- old injuries
what is posterior fat pad sign?
it’s when in elbow fracture fat pad is pushed posteriorly - it’s a sign of effusion and can be easily missed
what is view of buckle fracture?
little bump along bone - usually bone is smooth curve
what foreign body material can you see and not see?
can see metal & glass but not plastic & wood
what is pathological fracture?
fracture on weakened skeleton (usually when something normal that shouldn’t break bone breaks bone)
what are 4 easily missed fractures?
- posterior shoulder dislocation →on AP x-ray tricky to see
- supracondylar fracture →very common
- scaphoid fracture →common, x-ray, subtle loosening, blood supply can be disrupted
- Bennett’s fracture →articular surface of 1st metacarpal base, tendons pulling on thumb distal to fracture cause displacement, if missed arthritis
what are some x-ray limitations and what scan used to overcome?
- overlapping complexes hard to identify as 2D = overcome with CT
- some views can’t be seen depending on plane = overcome with CT
- sometimes can see fracture because blood or oedema fills space so see as different colour but some fractures are undisplaced →can be picked up on MRI
- soft tissue structures invisible to x-rays →overcome by ultrasound or MRI
what can indicate soft tissue fracture of knee on xray?
small avulsed bone fragments
what scans can be used to diagnose knee soft tissue injuries?
- x-ray for extensor mechanism injuries like quads or patellar tendon tears (tricky to examine cos pain)
- acute intra-articular soft tissue also might be sore = MRI (too deep for US)
what is common fracture of midfoot?
tarsal metatarsal (TMT) joint fracture subtle but can cause long term disability, Lisfranc injuries involve several TMT joints with multiple ligamentous avulsion fractures, best shown CT. looking for alignment is key
what is lipohaemarthrosis?
fat floating on blood in the suprapatellar recess, a specific sign of an intra-articular fracture
