Upper extremity lecture 2 Flashcards
What is a good “first line test” if you suspect pathology?
Radiograph
If an XR comes back negative, but you suspect fracture, what would be a good next step, and why?
CT: high spatial resolution, better for evaluating and characterizing bone
What imaging modality would be best for soft tissue injury, such as tendon or ligament pathology?
MRI: high contrast resolution
What imaging modality is best for finding abnormal edema?
MRI
MRI Standard Planes
axial, sagittal, coronal
MRI UE planes to optimize rotator cuff tears
coronal oblique (parallel to long axis of supraspinatus), sagittal oblique (perpendicular to long axis of supraspinatus), axial
XR standard view for long bones
2 views: AP and lateral (orthogonal planes)
XR standard view for joints
3 views: AP, lateral, oblique
XR standard view for shoulder
Trauma series: AP, Y-scapular (oblique), axillary
Nontrauma series: AP views in ER and IR
XR standard view for pelvis and hips
AP and frog leg lateral view
8 steps for how to read an X-ray
- Identify normal bones (what lives there?)
- Look for cortical continuity
- Look at alignment
- Look for any extra densities or lucencies within or outside bone
- Look at soft tissues (swelling, effusion)
- Look at adjacent joints
- Compare with prior studies, if any
- If there is still clinical concern for pathology, order CT or MRI
Wrist: Describe 3 arcs used to view X-ray
Arc I: proximal articular surface of scaphoid, lunate, triquetrum
Arc II: distal articular surface of scaphoid, lunate, triquetrum
Arc III: proximal articular surface of capitate and hamate
If there is no arc: dislocation
Wrist lateral view: what 4 structures should line up?
Radius, lunate, capitate, 3rd metacarpal
How to identify a fracture on an X-ray: 6 signs
- cortical discontinuity or deformity
- radiolucent fracture lines
- abnormally white or dense areas, representing overlapping bony fragments or impaction of bone
- extra or unexplained bony fragments
- soft tissue swelling or joint effusion
- callus formation in healing fractures (look fuzzy)
Gamekeeper’s Thumb
disruption of ulnar collateral ligament of first MCP joint, may be avulsion fracture of proximal phalanx at UCL
Stener Lesion
Gamekeeper’s thumb; displacement of UCL superficial to adductor pollicis aponeurosis; surgery required to heal avulsion fracture (adductor pollicis in the way)
Avascular necrosis of scaphoid: etiology
blood supply (from carpal branch of radial artery) to scaphoid bone begins distally and runs proximally, poor blood supply to proximal pole leads to AVN
If a patient has pain over the snuffbox of the wrist and X-ray is negative, what should be done?
if you have a high clinical suspicion of fracture, the wrist should be casted and pt. should get an MRI or repeat radiographs
posterior fat pad sign
abnormal radiolucency of posterior fat pad in elbow flexion; fat pad normally pressed into deep olecranon fossa by triceps tendon and anconeus (normally invisible on XR); visible when joint effusion present
give 1 pro and 1 con for the axillary view in a shoulder XP
Pro: better view than Y-scapular and more consistent
Con: can be a difficult/painful position for a person with a shoulder injury
Hill Sachs lesion: best view for XR
AP internal rotation
Hill Sachs lesion: what is it?
a cortical depression in the posterolateral head of the humerus, resulting from forceful impaction of the humeral head against the anteroinferior glenoid rim when the shoulder is dislocated anteriorly.
posterior shoulder dislocation: mechanism, etiology
humerus forced posteriorly in internal rotation; usually caused by convulsions, rarely by trauma
posterior shoulder dislocation: best imaging to diagnose, other pathology with similar presentation?
can “mimic” adhesive capsulitis; CT or MR best for viewing, often difficult to diagnose with XR
most common type of shoulder dislocation
anterior (95-97%)
posterior shoulder dislocation: what %?
2-4%
inferior (luxation) dislocation: what %?
0.5%
best imaging mode to view supraspinatus? best plane?
MRI (good for soft tissue); oblique coronal proton density or oblique sagittal fat sat proton density
Radiographic findings: chronic rotator cuff tears (3)
- high riding humerus (<7mm acromiohumeral distance)
- faceting and sclerosis in inferolateral acromion and superior aspect of greater tuberosity
- secondary osteophytosis in GH joint to maintain joint congruity
clinical findings: rotator cuff tears (signs and symtpoms-5)
- weak supraspinatus
- weak GH external rotation
- impingement
- age >/= 60 (>60%)
- night pain
full thickness tear-supraspinatus: imaging characteristics (what is visualized on MR?) (3)
- fully extends from bursal to articular surface
- nonvisualization of tendon
- fluid in expected location of tendon
calcific tendinosis
deposition of calcium hydroxyapatite at the insertion of the supraspinatus tendon
biceps tenosynovitis
biceps tendon sheath thickened with surrounding edema; visible on MR
subacromial subdeltoid bursitis
nonspecific effusion in subdeltoid bursa, not involving biceps tendon
