Shoulder Imaging Flashcards
What body structures/functions are most injured in the shoulder
- Humerus anatomy & fractures
- RTC (rotator cuff) tear
- Subacrominal pain syndromes
- Dislocation
- AC joint separation
Differential diagnosis for shoulder imaging
- Radiograph = initial study, acute pain, fx, dislocation, calorific tendonitis, arthritides
- MRI = MRA (arthrogram) = most frequently performed MRI study, glenoid labrum, RTC tear, tendon & bursa pathology, impingement in older adult
- CT = complex fractures, scapular fx, osseous glenoid fossa, humeral head
- Ultrasound = equivalent to MRI, bursitis, long head biceps tendinopathy or displacement, impingement in older adult, AC joint integrity, RTC re-tear, tendinopathy of RTC with/out arthroplasty
Shoulder radiograph basic projections
- GH joint (routine series): AP with IR (able to see lesser tuberosity); AP with ER (able to see greater tuberosity), Axillary view, Scapular Y view (anterior oblique view)
- AC joint: Ap with and w/o weights
- Scapula: AP, lateral, Y view
- Trauma series: Axillary view of GH, anterior oblique view
Describe acromiohumeral intervals
- AP view
- > 12 mm: shoulder dislocation, inferior subluxation
- 9-10 mm or 8-12 mm = normal
- 6-7 mm = thinning of supraspinatus tendon
- <6 mm = supraspinatus tear
What part of the clavicle is the most commonly fractured
- middle 1/3
- this is due to it being the thinnest part of the bone & it’s the only part of the bone not reinforced by attached musculature & ligaments
What is the typical MOI of an acromion fracture
- result from a downward blow to the shoulder
- superiorly displaced fractures may occur as a result of a superior dislocation of the shoulder
How are humerus fractures typically treated
- treated with supportive/hanging cast followed by a supportive splint & infrequently require open reduction
Describe the different fracture types of the scapula in an AP view
- Body or spine fracture (40-75%): usually result from a severe direct blow, as in a fall or MVA
- Coracoid fx (3-13%): coracoid process fractures usually result from a direct blow to the superior point of the shoulder or humeral head in an anterior shoulder dislocation or an avulsion fracture
MOI of a scapula fracture
- requires high energy trauma
- direct trauma to the shoulder region
- indirect trauma through falling on outstretched hand (FOOSH)
Describe a Bankart lesion
- fracture of the adjacent anteroinferior glenoid
- injury commonly occurs in the setting of an anterior glenohumeral dislocation
Describe a Hill-Sachs lesion
- posterolateral humeral head compression fracture
- typically secondary to recurrent anterior shoulder dislocations, as the humeral head comes to rest against the anteroinferior part of the glenoid
CT scans is diagnosing shoulder injries
- CT is comparable to MR in diagnosing Bankart lesions, Hill-sachs deformities, superior labral anterior to posterior (SLAP) tears, & full thickness RTC tears but is inferior to MR for diagnosing partial thickness RTC tears including burial sided tears
CT scan ABCS for shoulder
- Alignment of anatomy: deviations in alignment signal possible fracture, dislocation, or bone destruction
- Bone density: assess for any bone destruction, signifying disease or infection
- Cartilage/joint space: assess the glenohumeral & acronioclavicular joints for smooth chondral surfaces
- Soft tissues: asses the points of attachment of the rotator cuff tendons to bone
Basic shoulder protocol for MRI
- Alignment/anatomy: asses for disruption at points of soft tissue attachment to bone
- Bone signal: assess for marrow edema, stress fx, & osteochondral injuries, or define radiographically ambiguous fractures
- Cartilage: assess for abnormalities at the glenohumeral joint surfaces
- Edema: the “footprint of injury” edema will image as intermediate signal on anatomy, defining sequences & high signal on fluid sensitive sequences
- Soft tissues: assess continuity of rotator cuff muscles & tendons; assess the glens-humeral ligaments, 3 thickenings of the anterior capsule
What imaging modality best identifies & discriminates labral lesions in the shoulder
- MRA (MR arthography)
- Ultrasound and MRI are equivalent in allowing appreciation of focal tendon abnormalities
Appropriate imaging for acute shoulder pain of any etiology
- X-ray
Appropriate imaging for radiographs noncontributory, persistent significant pain, physical exam & Hx nonspecific
- MRI shoulder without contrast
Appropriate imaging for radiographs noncontributory, age less than 35 yrs, suspect labral tear with or w/o instability on physical exam
- MR shoulder without contrast
Appropriate imaging for radiographs noncontributory, questionable bursitis or long head of biceps tenosynovitis based on clinical findings including physical exam
- MRI shoulder without contrast
- Ultrasound shoulder
Appropriate imaging for normal radiograph or radiographs that demonstrate coracoacromial arch osteophytes/syndesmophytes, suspect rotator cuff tear/impingement over age 35 yrs
- MRI shoulder without contrast
- Ultrasound shoulder
- MR arthography shoulder
Appropriate imaging for radiographs noncontributory, previous total shoulder arthroplasty, suspect rotator cuff tear
- Ultrasound shoulder
- X-ray arthrography shoulder
- CT arthrography shoulder
Appropriate imaging for radiographs noncontributory, status post prior rotator cuff repair, suspect re-tear
- MRI shoulder without contrast
- MR arthrography shoulder
- Ultrasound shoulder
Appropriate imaging for radiographs noncontributory, suspect septic arthritis
- Ultrasound arthrocentesis (joint aspiration) shoulder
- X-ray arthrocentesis shoulder
- Aspiration is the procedure of choice
- If clinical concern warrants: MRI shoulder without & with contrast
Describe fracture of the proximal humerus
- Fx of surgical neck common in osteoporotic females & typically nondisplaced
- MOI: ground level falls in elderly, MVA in younger adults
- Imaging: radiographs for diagnosis; CT may be needed to define complex humeral head fractures
Describe a labral tear SLAP lesion
- Due to avulsion, tearing within substance, or tearing in relation to biceps tendon
- Symptoms: pain worse with overhead movements; clicking, catching, a sense of instability
- MOI: injured acutely in a fall or dislocation or from repetitive overhead movements
- Imaging: initial radiographs followed by MR arthrography
Describe impingement syndrome
- Mechanical compression of the rotator cuff tendons &/or posterior capsule in subacromial space
- Symptoms: pain is reproduced with overhead movement
- Imaging: initial radiographs followed by MRI or MSUS
Describe a rotator cuff tear (RTC tear)
- most tears are in the supraspinatus
- MOI: result from an acute trauma (dislocation, fall, or forced abduction of the arm)
- Imaging: radiographs to rule out Fx, MRI or MSUS to define tear
