Shoulder Imaging

Question 1

What body structures/functions are most injured in the shoulder

Answer 1

• Humerus anatomy & fractures
• RTC (rotator cuff) tear
• Subacrominal pain syndromes
• Dislocation
• AC joint separation

Question 2

Differential diagnosis for shoulder imaging

Answer 2

• 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

Question 3

Shoulder radiograph basic projections

Answer 3

• 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

Question 4

Describe acromiohumeral intervals

Answer 4

• 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

Question 5

What part of the clavicle is the most commonly fractured

Answer 5

• 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

Question 6

What is the typical MOI of an acromion fracture

Answer 6

• result from a downward blow to the shoulder
• superiorly displaced fractures may occur as a result of a superior dislocation of the shoulder

Question 7

How are humerus fractures typically treated

Answer 7

• treated with supportive/hanging cast followed by a supportive splint & infrequently require open reduction

Question 8

Describe the different fracture types of the scapula in an AP view

Answer 8

• 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

Question 9

MOI of a scapula fracture

Answer 9

• requires high energy trauma
• direct trauma to the shoulder region
• indirect trauma through falling on outstretched hand (FOOSH)

Question 10

Describe a Bankart lesion

Answer 10

• fracture of the adjacent anteroinferior glenoid
• injury commonly occurs in the setting of an anterior glenohumeral dislocation

Question 11

Describe a Hill-Sachs lesion

Answer 11

• 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

Question 12

CT scans is diagnosing shoulder injries

Answer 12

• 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

Question 13

CT scan ABCS for shoulder

Answer 13

• 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

Question 14

Basic shoulder protocol for MRI

Answer 14

• 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

Question 15

What imaging modality best identifies & discriminates labral lesions in the shoulder

Answer 15

• MRA (MR arthography)
• Ultrasound and MRI are equivalent in allowing appreciation of focal tendon abnormalities

Question 16

Appropriate imaging for acute shoulder pain of any etiology

Answer 16

• X-ray

Question 17

Appropriate imaging for radiographs noncontributory, persistent significant pain, physical exam & Hx nonspecific

Answer 17

• MRI shoulder without contrast

Question 18

Appropriate imaging for radiographs noncontributory, age less than 35 yrs, suspect labral tear with or w/o instability on physical exam

Answer 18

• MR shoulder without contrast

Question 19

Appropriate imaging for radiographs noncontributory, questionable bursitis or long head of biceps tenosynovitis based on clinical findings including physical exam

Answer 19

• MRI shoulder without contrast
• Ultrasound shoulder

Question 20

Appropriate imaging for normal radiograph or radiographs that demonstrate coracoacromial arch osteophytes/syndesmophytes, suspect rotator cuff tear/impingement over age 35 yrs

Answer 20

• MRI shoulder without contrast
• Ultrasound shoulder
• MR arthography shoulder

Question 21

Appropriate imaging for radiographs noncontributory, previous total shoulder arthroplasty, suspect rotator cuff tear

Answer 21

• Ultrasound shoulder
• X-ray arthrography shoulder
• CT arthrography shoulder

Question 22

Appropriate imaging for radiographs noncontributory, status post prior rotator cuff repair, suspect re-tear

Answer 22

• MRI shoulder without contrast
• MR arthrography shoulder
• Ultrasound shoulder

Question 23

Appropriate imaging for radiographs noncontributory, suspect septic arthritis

Answer 23

• Ultrasound arthrocentesis (joint aspiration) shoulder
• X-ray arthrocentesis shoulder
• Aspiration is the procedure of choice
• If clinical concern warrants: MRI shoulder without & with contrast

Question 24

Describe fracture of the proximal humerus

Answer 24

• 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

Question 25

Describe a labral tear SLAP lesion

Answer 25

- 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

Question 26

Describe impingement syndrome

Answer 26

- 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

Question 27

Describe a rotator cuff tear (RTC tear)

Answer 27

- 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