Shoulder/Arm

Francesca D. Beaman

Jeffrey J. Peterson

Thomas H. Berquist

▪ FRACTURES/DISLOCATIONS: PROXIMAL HUMERAL FRACTURES

KEY FACTS

Fractures of the proximal humerus usually occur in the elderly.
Proximal humeral fractures account for 5% of all skeletal fractures.
Fractures in the elderly are usually caused by a fall.
Fractures tend to follow the physeal lines dividing the humerus into four parts: humeral head, greater tuberosity, lesser tuberosity, and humeral shaft.
Fragments are considered displaced if separated by 1 cm or angulated 45 degrees or greater (Table 6-1).
The majority of fractures (85%) are undisplaced.
Undisplaced fractures are treated conservatively. Displaced, especially comminuted or four-part fractures, require surgery or arthroplasty.
Complications:
- Adhesive capsulitis
- Neurovascular injury
- Malunion, nonunion
- Avascular necrosis

Table 6-1 NEER CLASSIFICATION

Fracture Type	Description
One-part (80% of cases)	No fragment displacement >1 cm or angulated >45 degrees
Two-part (13% of cases)	One fragment displaced >1 cm or angulated >45 degrees
Three-part (3% of cases)	Two fragments displaced or angulated as in “two part”
Four-part (4% of cases)	Three fragments displaced or angulated as above

FIGURE 6-1. The four parts of proximal humeral fractures.

FIGURE 6-2. Proximal humeral fracture. Grashey views of a four-part proximal humeral fracture in two different patients with (A) minimal and (B) moderate displacement of the fragments.

SUGGESTED READING

Berquist TH. MRI of the Musculoskeletal System. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2012.

Lin DJ, Wong TT, Kazam JM. Shoulder arthroplasty, from indications to complications: what the radiologist needs to know. Radiographics. 2016;36(1):192-208.

Sandstrom CK, Kennedy SA, Gross JA. Acute shoulder trauma: what the surgeon wants to know. Radiographics. 2015;35(2):475-492.

▪ FRACTURES/DISLOCATIONS: GLENOHUMERAL DISLOCATIONS

KEY FACTS

Dislocations of the glenohumeral joint are the most common dislocation (50% of all dislocations).
Dislocations may be anterior (96%), posterior (2% to 4%), or, less frequently, superior or inferior.
Anterior dislocations are usually the result of falls with the arm abducted and externally rotated.
- The humeral head is frequently impacted against the labrum, resulting in a posterolateral impaction fracture (67% to 76%) or Hill-Sachs lesion.
- The anterior inferior labrum or glenoid may also be injured (50%), and such an injury is referred to as a Bankart lesion (may be cartilaginous or osseous).
- Most anterior dislocations are obvious on routine radiographs.
Posterior dislocations occur with seizures, shock therapy, or falls with the arm abducted and internally rotated. The patient’s arm is internally rotated, and external rotation is blocked.
- Radiographic features may be subtle.
  - Humeral head fixed in internal rotation (100%)
  - Joint may appear widened
  - Overlap of humeral head and glenoid absent or distorted
  - “Trough line” oriented vertically in the humeral head, caused by impaction fracture of the anteromedial humeral head resulting from contact with the posterior glenoid
  - Lesser tuberosity fracture (25%)
- Scapular “Y” view makes diagnosis most obvious.
- Treatment of dislocations is closed reduction unless there are significant associated fractures.
Complications of dislocations:
- Associated fractures: lesser tuberosity, coracoid, greater tuberosity, subscapularis avulsion
- Recurrent dislocation
- Degenerative arthritis
- Neurovascular injury

FIGURE 6-3. Anterior dislocation. Anteroposterior (AP) (A) and axillary (B) radiographs show an anterior dislocation of the humeral head. (C) AP radiograph in another patient shows an anterior dislocation with fracture fragments laterally. (D) Axial T2 fat-saturated magnetic resonance (MR) image shows a Hill-Sachs lesion (arrow) in the posterior humeral head.

FIGURE 6-3. (continued)

FIGURE 6-4. Posterior dislocation. (A) Anteroposterior (AP) view shows overlap of the glenoid and humeral head with an anteromedial impaction fracture (arrow). (B) Axillary view shows the humeral head fracture impacted into the posterior glenoid locking the shoulder in internal rotation.

FIGURE 6-4. (continued)

SUGGESTED READING

Atef A, El-Tantawy A, Gad H, Hefeda M. Prevalence of associated injuries after anterior shoulder dislocation: a prospective study. Int Orthop. 2016;40(3):519-524.

Gyftopoulos S, Wang A, Babb J. Hill-Sachs lesion location: does it play a role in engagement? Skeletal Radiol. 2015;44(8):1129-1134.

Sebro R, Oliveira A, Palmer WE. MR arthrography of the shoulder: technical update and clinical applications. Semin Musculoskelet Radiol. 2014;18(4):352-364.

▪ FRACTURES/DISLOCATIONS: ACROMIOCLAVICULAR DISLOCATION

KEY FACTS

Dislocations of the acromioclavicular (AC) joint (12%) are less common than glenohumeral (85%) shoulder dislocations.
Most commonly results from a fall striking the point (AC joint region) of the shoulder.
Injuries may be partial or complete (Table 6-2).
Routine clavicle radiographs may be normal with incomplete ligament injury. Weight-bearing views are useful to classify injuries (Types I and II).
Closed reduction is usually used for Types I and II injuries. Internal fixation is frequently required for Types III to VI lesions.

Table 6-2 ACROMIOCLAVICULAR DISLOCATIONS

Classification	Radiographic Features
Type I, few fibers torn	Normal
Type II, rupture of the capsule and AC ligaments	Joint widened, clavicle may be slightly subluxed
Type III, same as Type II, but coracoclavicular ligaments also disrupted	Elevated clavicle, coracoclavicular space ↑
Types III and V, same as Type III	Same as Type III, but posterior clavicular displacement with Type IV and superior with Type V
Type VI, disruption of all ligaments with anterior entrapment	Clavicle trapped below coracoid
AC, acromioclavicular.

FIGURE 6-5. Acromioclavicular (AC) joint injuries. Type I: AC sprain, few fibers torn. Type II: disruption of the AC ligaments with coracoclavicular ligaments intact. Type III: disruption of the AC and coracoclavicular ligaments. Type IV: disruption of both ligament complexes with posterior clavicular displacement. Type V: disruption of both ligament complexes with marked superior clavicular displacement. Type VI: disruption of both ligament complexes with anterior entrapment beneath the coracoid.

FIGURE 6-6. Acromioclavicular (AC) separation. (A) Anteroposterior (AP) radiograph shows a normal AC joint space. (B) Grashey and scapular-Y (C) views show marked superior displacement of the clavicle (Type V).

FIGURE 6-6. (continued)

SUGGESTED READING

Kim AC, Matcuk G, Patel D, et al. Acromioclavicular joint injuries and reconstructions: a review of expected imaging findings and potential complications. Emerg Radiol. 2012;19(5):399-413.

Loriaut P, Casabianca L, Alkhaili J, et al. Arthroscopic treatment of acute acromioclavicular dislocations using a double button device: clinical and MRI results. Orthop Traumatol Surg Res. 2015;101(8):895-901.

Nemec U, Oberleitner G, Nemec SF, et al. MRI versus radiography of acromioclavicular joint dislocation. Am J Roentgenol. 2011;197(4):968-973.

▪ FRACTURES/DISLOCATIONS: STERNOCLAVICULAR DISLOCATIONS

KEY FACTS

Dislocations of the sternoclavicular joint are uncommon (3% of shoulder dislocations).
Usually occurs with indirect shoulder trauma. Anterior dislocation is the result of posterolateral forces transmitted medially. Posterior dislocation is the result of direct anterior trauma. A majority of dislocations are anterior (>90%).
Radiographic evaluation is difficult with routine views because of bone overlap. Computed tomography (CT) is the technique of choice to evaluate the sternoclavicular joint.
Treatment is usually conservative.
Complications are most common with posterior dislocations: tracheal rupture, arch vessel laceration, and neural injury.

FIGURE 6-7. Sternoclavicular fracture dislocation. (A) Coronal reformatted computed tomography (CT) image shows a fracture (arrow) of the right clavicular head with disruption of the sternoclavicular joint. (B) Axial and sagittal-reformatted (C) CT images in another patient show posterior dislocation of the right clavicular head (arrow). Note normal alignment of the left sternoclavicular joint in (B).

FIGURE 6-7. (continued)

SUGGESTED READING

Khorashadi L, Burns EM, Heaston DR, et al. Posterior dislocation of the sternoclavicular joint. Radiol Case Rep. 2015;6(3):439.

Morell DJ, Thyagarajan DS. Sternoclavicular joint dislocation and its management: a review of the literature. World J Orthop. 2016;7(4):244-250.

Restrepo CS, Martinez S, Lemos DF, et al. Imaging appearances of the sternum and sternoclavicular joints. Radiographics. 2009;29(3):839-859.

▪ FRACTURES/DISLOCATIONS: CLAVICLE FRACTURES

KEY FACTS

Clavicle fractures are especially common in children.
Injury occurs after a fall on the outstretched hand.
Fractures most commonly involve the middle third (80%). The distal clavicle is involved in 15%, and medial clavicle in 5%.
Routine anteroposterior (AP) radiographs are usually adequate for diagnosis.
Most clavicle fractures can be treated with closed reduction. Distal fractures involving the AC joint and ligaments may require internal fixation.
Complications include malunion, nonunion (1% to 2%), and degenerative arthritis when there is joint involvement.

FIGURE 6-8. Clavicle fractures. Anteroposterior (AP) radiographs show mildly displaced mid (A) and distal (B) clavicular fractures (arrow) without widening of the acromioclavicular (AC) joint. (C) AP radiograph in another patient shows a midclavicular fracture with override of the fracture fragments, which was treated with hardware fixation (D).

FIGURE 6-8. (continued)

SUGGESTED READING

Melenevsky Y, Yablon CM, Ramappa A, et al. Clavicle and acromioclavicular joint injuries: a review of imaging, treatment, and complications. Skeletal Radiol. 2011;40(7):831-842.

Suppan CA, Bae DS, Donohue KS, et al. Trends in the volume of operative treatment of midshaft clavicle fractures in children and adolescents: a retrospective, 12-year, single-institution analysis. J Pediatr Orthop B. 2016;25(4):305-309.

▪ FRACTURES/DISLOCATIONS: POSTTRAUMATIC OSTEOLYSIS

KEY FACTS

Posttraumatic osteolysis occurs in the distal clavicle.
Patients present with pain and weakness.
Differential diagnosis includes rotator cuff tear and AC separation.
Routine radiographs may be normal early, but later erosive changes occur in the distal clavicle. Magnetic resonance imaging (MRI) shows edema (increased signal on T2-weighted images) in the distal clavicle and joint.
When conservative therapy fails, the distal clavicle can be resected.

FIGURE 6-9. Posttraumatic osteolysis. Anteroposterior (AP) radiographs of the same patient show widening (arrow) of the right acromioclavicular (AC) joint (A) and a normal left (B) joint. (C) AP radiograph in another patient shows irregularity of the distal clavicle (arrow). Coronal T2 fat-saturated (D) and axial proton density fat-saturated (E) magnetic resonance (MR) images in the same patient as (C) show irregularity of the distal clavicle with joint inflammation (arrow). A = acromion.

FIGURE 6-9. (continued)

SUGGESTED READING

Kassarjian A, Llopis E, Palmer WE. Distal clavicular osteolysis: MR evidence for subchondral fracture. Skeletal Radiol. 2007;36(1):17-22.

Rios CG, Mazzocca AD. Acromioclavicular joint problems in athletes and new methods of management. Clin Sports Med. 2008;27(4):763-788.

▪ FRACTURES/DISLOCATIONS: SCAPULAR FRACTURES

KEY FACTS

Fractures of the scapula are uncommon (1% of all skeletal fractures).
Injury is the result of direct trauma.
Scapular fractures can be overlooked on AP and lateral radiographs.
Associated fractures of the clavicle and ribs occur in 88%.
Articular involvement is best evaluated with CT.
Conservative therapy is usually preferred unless there is significant articular deformity or displacement.

FIGURE 6-10. Scapular fracture. Anteroposterior (AP) radiograph (A) and axial computed tomography (CT) image (B) show a displaced fracture of the scapular neck (arrow). Note, a midclavicular fracture and rib fractures can also be seen on the radiograph. (C) Lateral radiograph in another patient shows a fracture (arrow) of the inferior scapular body.

SUGGESTED READING

Armitage BM, Wijdicks CA, Tarkin IS, et al. Mapping of scapular fractures with three-dimensional computed tomography. J Bone Joint Surg Am. 2009;91(9):2222-2228.

Lewis S, Argintar E, Jahn R, et al. Intra-articular scapular fractures: outcomes after internal fixation. J Orthop. 2013;10(4):188-192.

Ropp AM, Davis DL. Scapular fractures: what radiologists need to know. Am J Roentgenol. 2015;205(3):491-501.

▪ FRACTURE/DISLOCATIONS: HUMERAL SHAFT FRACTURES

KEY FACTS

Humeral shaft fractures account for 1% of all fractures.
Location of the fracture in relation to muscle attachments affects the direction of displacement. Proximal third fractures displace medially because of pectoral muscle forces. Fractures distal to the deltoid insertion are abducted by the deltoid muscle.
69% of fractures involve the midshaft.
Fractures at the mid/distal third junction are difficult to manage. Radial nerve and nutrient artery injury may occur.
Complication of humeral shaft fractures includes nonunion, malunion, infection, radial nerve injury (5% to 10%), and compartment syndrome.

FIGURE 6-11. Fractures of the humerus are described by location as upper, middle, or lower third.

FIGURE 6-12. Anteroposterior (AP) radiographs show a four-part proximal humeral fracture extending into the proximal diaphysis (A) treated with shoulder prosthesis (B). C) AP radiograph in another patient shows a midhumeral shaft fracture with separation and angulation of the fragments. This can result in soft tissue interposition and nonunion and was treated with open reduction and internal fixation using a compression plate (D).

SUGGESTED READING

Ricci FP, Barbosa RI, Elui VM, et al. Radial nerve injury associated with humeral shaft fracture: a retrospective study. Acta Ortop Bras. 2015;23(1):19-21.

Walker M, Palumbo B, Badman B, et al. Humeral shaft fractures: a review. J Shoulder Elbow Surg. 2011;20(5):833-844.

▪ ROTATOR CUFF DISEASE: BASIC CONCEPTS

KEY FACTS

The rotator cuff is composed of the supraspinatus, infraspinatus, teres minor, and subscapularis tendons.
The rotator cuff is responsible for up to 50% of muscle effort for abduction and 80% for external rotation.
Rotator cuff tear (Table 6-3) most commonly results from impingement of the cuff between the coracoacromial arch and the humeral head. Vascular insufficiency may play a role. Chronic sports trauma and occupational overuse may result in cuff tears. Acute trauma is an infrequent cause of isolated rotator cuff tears.
Imaging of rotator cuff disease can be accomplished with routine radiographs, ultrasound, CT arthrography, and conventional MRI or magnetic resonance (MR) arthrography. MRI is the technique of choice at most institutions.

Table 6-3 ETIOLOGY OF ROTATOR CUFF TEARS

Primary Impingement

Abnormal acromial configuration

Acromioclavicular osteophytes

Os Acromiale

Thickened coracoacromial ligament

Secondary extrinsic impingement

Ischemia

Trauma

FIGURE 6-13. (A) Normal Grashey view of the shoulder shows a preserved humeroacromial distance, normal greater tuberosity (thin arrow), and no abnormality of the acromioclavicular (AC) joint (thick arrow). (B) Grashey view radiograph in a patient with chronic rotator cuff disease shows a narrowed humeroacromial distance, prominent subacromial osteophyte (white arrow) causing impingement, significant AC joint degenerative hypertrophy and bony irregularity of the greater tuberosity (black arrow).

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