JC Block C - Diagnostic Radiology - Musculoskeletal Flashcards
4 things to check for MSS imaging
Check patient’s demographics (make sure right patient right time), site markers (e.g. R or L)
Two orthogonal views (3D anatomy)
Compare with other side (if applicable)
Compare to old radiographs (if available) – time course hints on etiology
Approach to MSS imaging interpretation
Name of the views
Label all bones **
AP and oblique views
System for assessing alignment of cervical spine on Xray
Lateral view:
Anterior longitudinal line (any steps?)
Posterior longitudinal line (any steps?)
Posterior pillar line
Spinolaminar line
Spinous process line
AP view:
Are the spinal processes joined by a straight line? Any deviation?
Are the spinal processes equidistant from each other? Any widened gap?
Features of cervical spine facet joint dislocation on Xray
Rotated facets on lateral view
Widening of interspinous space on AP view
System for assessing alignment of wrist on Xray
AP view:
proximal and distal row of carpal bones should be aligned.
Curves joining them should be smooth; and
none of them should overlap.
Lateral:
line joining radius to lunate should intersect with capitate
R-L-C form a line
Features of distal radial/ wrist fracture on X-ray
Alignment of carpal bone rows is disrupted on AP view
Capitate is dislocated from “cup” of lunate, Line joining radius to lunate to Capitate is disrupted on Lateral view
Lesion?
Humeral head fracture
fracture complexity better appreciated in CT)
Pelvic X-ray
- How to assess pelvic alignment on X-ray
Assess:
1. Shenton’s line (= continuous line from medial femoral neck to inferior
aspect of superior pubic ramus) – should be smooth
May be disrupted in femur neck fracture
- Iliopectineal line
- Ilioischial line (to the ring)
Features of femur fracture on X-ray
Disruption of Shenton’s line: line from medial femoral neck to inferior aspect of superior pubic ramus
Increase sclerosis due to impaction
Femoral neck fracture
- Most common location of fracture
- Complications
Commonest location = subcapital
Non-displaced vs. displaced (displaced fractures tend to compromise the
blood supply to the femoral head)
Complication: osteonecrosis/ avascular necrosis of femoral head
Displaced fractures
High intracapsular pressure due to fracture, Poor venous return
Low arterial perfusion
Describe picture
Series of plain X-ray showing healing fracture:
Acute fracture line callous formation complete heal of fracture line
Describe picture, identify lesion
Complications?
Fractures of base of metatarsals
Dislocated from the tarsal bones (lateral shift of metatarsal)
Could be Lisfranc fracture dislocation:
- Tarsometatarsal dislocation caused by indirect rotational forces through hyperplantarflexed forefoot
- Can be missed on 1 Xray view
- Can cause progressive foot deformity, chronic pain, dysfunction, litigation
Describe lesion
Low bone density/ Bone Lucency
Causes of bone lucency on X-ray
Causes of bone sclerosis on X-ray
Impacted/ healing fracture (local sclerosis)
Bone tumour (primary vs. metastasis)
Systemic process (diffuse sclerosis):
Myelofibrosis
Sickle cell
Paget’s disease (disorder of bone remodeling)
Features of Enchondroma on X-ray
enchondroma (benign):
Well-defined margin
Central lucency +/- chondroid calcification
Bones are weakened look for pathological fracture
Describe picture
anterior dislocation of shoulder, glenohumeral dislocation:
Fracture of inferior glenoid margin (Bankart fracture)
Cortical impaction of superior posterior aspect of humerus(Hill-Sachs deformity)
Imaging modalities for soft tissue injuries
Soft tissue (e.g. ligamentous injury, haemarthrosis from intraarticular fracture):
USG: superficial structures (e.g. soft tissue tumor, ligaments on shoulder joint)
MRI:
Good delineation of neurovascular bundle - e.g. compress on nerve roots
Good to assess disc space, joint space in spine, paravertebral soft tissue
Good for spinal infections, discitis
Describe picture
discitis:
Enhancement (fluid material)
Central necrosis
