Acromio-clavicular (AC) separation is an injury to the ligamentous structures of the AC joint. On AP radiographs of the shoulder, the inferior aspect of the distal clavicle should align with the inferior aspect of the acromion. In type I injuries, there is a sprain or partial tear to the AC ligament and imaging will appear normal. In type II injuries, the AC ligament is torn and the space between the distal clavicle and acromion may appear wider (as compared to the other shoulder) and the distal clavicle may be slightly superiorly displaced in relation to the acromion, but less than 100%. Type III injuries involve a tear of the AC and coraco-clavicular (CC) ligaments and the distal clavicle is 100% displaced superiorly in relation to the acromion. Type IV injuries are rare and occur when the distal clavicle is displaced posteriorly. Type V injuries are severe type III injuries; in these, the distal clavicle punctures the trapezius muscle. Type VI injuries occur when the distal clavicle is inferiorly displaced below the coracoid.
AC separation injuries occur when patients fall or sustain a blow to the top of the shoulder. Physical findings include swelling and pain on palpation of the AC joint. Patients will have pain with cross arm testing (reaching from the affected arm to the opposite shoulder). Radiographs can help determine the severity and type of the injury. Type I, II, and III injuries are treated conservatively with a sling for comfort and activity as tolerated. Type IV, V, and VI injuries are rare, and treated surgically on an outpatient basis. Patients with symptomatic arthritis as a result of these injuries may ultimately be treated with a distal clavicle excision (Mumford procedure).
AP chest radiographs can be helpful in providing a comparative view of the unaffected AC joint.
Weighted arm views can aid in the diagnosis but do not change overall management and are not routinely recommended.
Figure 9.1 Grade 2 Acromio-Clavicular Separation.
AP view of the left shoulder demonstrates mild widening of the left acromio-clavicular joint (it measured 12 mm; the upper limit of normal is 8 mm). The distance between the coracoid process and undersurface of the clavicle remains normal (upper normal is 13 mm). The findings are consistent with grade 2 acromio-clavicular separation. Grade 1 A-C separation is radiographically occult.
Figure 9.3 Remote Right Acromio-Clavicular Separation.
An AP view of the upper chest shows linear mature heterotopic ossification between the right coracoid and clavicle (arrow) and an abnormal, foreshortened and mildly irregular appearance of the distal end of the right clavicle. These findings indicate that the patient has had a high grade A-C separation in the past (months or years ago).
Figure 9.4 Mumford Procedure.
An AP view of the left shoulder shows prior resection of the distal left clavicle (Mumford procedure). This is done to alleviate or prevent further supraspinatus tendinopathy. Notice the rounded, well-corticated edge of the resected distal left clavicle. This should not be confused with acromio-clavicular separation.
Acromion fractures typically result from direct trauma to the superior shoulder. These fractures are often subtle and are best seen on the axillary and/or scapular Y views of the shoulder. Acromial fractures may be confused with os acromionale. Os acromionale occurs when the ossification center at the tip of the acromion fails to fuse with the rest of the acromion. Os acromionale may be symptomatic and cause pain. An os acromiale can be differentiated from an acute fracture by its sclerotic and rounded edges. CT and MRI can often better illustrate the diagnosis.
Figure 9.6 Right Acromial Fracture.
A, B: A scapular Y view of the right shoulder (A) shows a fracture of the right acromial process (arrow). Because of the orientation of the fracture plane, the fracture is invisible on the AP view (B). Acromial fractures (and fractures of the scapula in general) can be very subtle and may only be visible on a single view of a radiographic study.
Acromion fractures typically result from a direct downward blow to the shoulder, but may also occur in superiorly dislocated gleno-humeral joint injuries. Patients will be point tender over the acromion. Symptomatic os acrominale may present with impingement and rotator cuff pain. MRI will often show bony edema surrounding the unfused synchondrosis of the os indicative of shear forces across the region. Hypertrophic changes (osteophytosis, subchondral sclerosis) are frequently seen as well if the os is unstable. Symptomatic patients may require operative treatment if conservative measures fail. Most acromion fractures can be treated conservatively, though displaced fractures may require operative fixation.
Acromial fractures are often subtle and seen frequently on only one radiographic view.
Most patients with os acrominale are asymptomatic. If present, symptoms attributable to an unstable os acromiale are generally mild and can be treated conservatively.
An unstable os acromiale can contribute to supraspinatus tendinopathy and tears. These complications are best imaged with shoulder MRI.
Figure 9.8 Os Acromiale.
A-C: AP, scapular Y and axillary views of the right shoulder show the typical appearance of an os acromiale. This is a normal variant and is caused by failure of fusion of the ossification center of the acromion to the scapular spine. Notice the sclerotic and somewhat rounded edges of the os acromiale (arrow) and compare that to the jagged or straight lines of the fracture planes seen in the acromial fractures. It is important to be able to differentiate between an os acromiale and acromial fractures. An os acromiale may be a cause of pain: motion at the synchondrosis can lead to degenerative and hypertrophic changes about the synchondrosis. This, in turn, can contribute to supraspinatus tendinopathy and tears.
Anterior glenohumeral dislocations typically occur with forced abduction and external rotation to the arm. Anterior dislocations account for 90% of glenohumeral dislocations and can be identified by the humeral head displaced anterior and inferior to the glenoid. Axillary and/or scapular Y views can confirm the direction of the dislocation. Hill–Sachs lesions can be seen as deformation of the humeral head and occur as a result of the humeral head colliding against the anteroinferior rim of the glenoid. A bony Bankhart lesion is a fracture of the anteroinferior glenoid rim caused by the dislocating humeral head. A labroligamentous Bankart lesion results more frequently than a bony Bankart lesion; the former can be detected with MRI.
Anterior glenohumeral dislocations are the most common joint dislocations presenting to the emergency department. Radiographs should be obtained when the diagnosis is in question and post reduction radiographs are mandatory to confirm reduction and assess for the presence of fractures. Hill–Sachs and bony Bankart fractures are easier to appreciate on the post reduction radiographs. Pre and post reduction neurovascular exams should be performed as axillary nerve and artery injuries can occur. Patients should be placed in a sling and swathe post reduction and orthopedic follow-up is necessary. Repeat dislocation risk is highest in young athletes. Patients over age 40 are at risk for concomitant rotator cuff injuries associated with their dislocation.
Reduction may be performed without radiographs when the diagnosis is strongly suspected. A successful reduction becomes more difficult the longer the joint remains dislocated.
Patients with Bankart fractures are at higher risk for joint instability and recurrent dislocation.
Intraarticular lidocaine injections can often be administered instead of procedural sedation for analgesia during reduction. Injections of 20 cc of 1% lidocaine or marcaine into the joint after sterile preparation have been shown to be as effective as procedural sedation and can reduce the cost and the total time spent in the ED by several hours.
Reduction can be confirmed clinically by ranging the patient’s humerus through full external and internal rotation and flexion/abduction of the glenohumeral joint to 90°.
Figure 9.12 Hill–Sachs and Bankart Fractures.
A, B: Axial fat saturated T1-weighted images at the level of the superior aspect of the humeral head (A) and mid glenoid (B) demonstrate a hatchet-like deformity in the postero-lateral aspect of the humeral head consistent with a Hill–Sachs fracture (arrow) and a bony Bankart fracture (arrowhead). These are consistent with a prior anterior shoulder dislocation event. At this time, the humeral head is located within the glenoid.
Posterior glenohumeral dislocations occur as a result of forced posterior and internal rotation of the shoulder, often as a result of seizures, electrocutions, falls, and automobile accidents. The diagnosis should be suspected when the humeral head is internally rotated and the greater tuberosity is not seen on the AP view (light bulb sign). Axillary or Y scapular views must be obtained to confirm the diagnosis as posterior glenohumeral dislocations can be extremely subtle on the anterior–posterior views and are the most frequently missed joint dislocations. CT-scan imaging can be helpful to confirm the diagnosis when in doubt.
Figure 9.13 Posterior Shoulder Dislocation.
A-C: Axillary, AP, and scapular Y views of the right shoulder demonstrate posterior dislocation of the right humeral head. There is an impaction fracture on the anterior aspect of the humeral head (“anterior trough impaction fracture” or “reverse Hill–Sachs fracture”).
Axillary or scapular Y views must be obtained in addition to the AP views to evaluate for posterior glenohumeral dislocation. Patients who hold their arm in internal rotation and cannot be externally rotated should be evaluated for posterior dislocation. Fractures of the posterior glenoid rim (reverse Bankart) or anterior humeral head (anterior trough impaction) may make reduction more difficult; posterior glenohumeral dislocations frequently require reduction in the operating room.
Figure 9.14 Posterior Shoulder Dislocation.
A single axial CT image through the left shoulder of a different patient demonstrates a prominent anterior trough impaction fracture on the anterior aspect of the left humeral head (arrowhead). This fracture is obtained when the humeral head impacts against the posterior glenoid rim during a posterior dislocation event. At this time, the left humeral head is located within the glenoid.
Posterior shoulder dislocations are the most frequently missed joint dislocations. Axillary and/or scapular Y view must be obtained on every patient to adequately evaluate for posterior dislocation. The findings on the AP view are extremely subtle (loss of the normal parallelism between the humeral head articular surface and anterior glenoid rim).
The diagnosis can often be excluded clinically if the patient’s shoulder can be fully externally rotated with the elbow at the patient’s side.
Luxatio Erecta occurs when the humeral head is inferiorly dislocated from the glenoid. This can easily be identified on AP shoulder views and frequently on AP chest radiographs obtained during initial trauma evaluations.
Luxatio Erecta is the least common shoulder dislocation representing only 1-3% of all shoulder dislocations. However, it is commonly associated with neurovascular injury to the axillary nerve and/or artery. Diagnosis can be suspected in patients who present with their arm raised over their heads with the shoulder fixed in abduction and forward elevation. Reduction can be difficult as the humeral head can often become “locked” between the glenoid and ribs. Axial traction and often anterior traction on the humeral head may be necessary to free the humerus from the glenoid rim. CT angiograms can help evaluate for axillary artery injuries when suspected. Orthopedic and vascular surgery consultations should be considered.
Luxatio erecta is the least common of the shoulder dislocations, but has the highest association with vascular and nerve injuries.
Diagnosis should be suspected in patients who present with their arm raised over their heads with the inability to adduct or lower their arms.
Figure 9.15 Luxatio Erecta.
A, B: AP and axillary views of a shoulder demonstrate the typical appearance of luxatio erecta: the humeral head is dislocated inferior to the glenoid and the upper extremity is “stuck” in an abducted position. On the axillary view, the humeral head projects over the glenoid and acromion because the humeral head is dislocated inferior to the glenoid fossa.
Calcific tendonitis is caused by deposition of calcium hydroxyapatite within the tendons of the rotator cuff. These deposits are radiographically apparent. The involved tendon is determined by the location of the calcium hydroxyapatite deposit: the supraspinatus, infraspinatus, and teres minor attach to the greater humeral tuberosity from anterior to posterior while the subscapularis attaches primarily to the lesser humeral tuberosity anteriorly.
Calcific tendonitis usually occurs in patients 30-50 years old with a higher incidence in diabetics. While not always painful when seen on radiographs, the calcium deposit can become painful during the resorptive phase. Patients present with acute onset pain that may mimic a rotator cuff tear, gouty attack, or infection. Calcific tendonitis is typically a self-limited condition and resolves on its own with time. Additional treatment options include NSAID, physical therapy, and corticosteroid injections. Image-guided percutaneous aspiration may be performed but does not alter the long-term outcome. Surgical resection is reserved for refractory cases.
Calcific tendonitis is rarely associated with rotator cuff tears.
Calcific tendonitis goes through four clinical stages: The formative stage presents with an unknown trigger and the calcium deposit resembles chalk. The resting phase occurs once the calcific deposit is solidified and typically is not painful. The resorptive phase is painful due to an associated inflammatory reaction caused by the calcium breaking down. The material at this phase resembles toothpaste. The tendon returns to normal in the postcalcific phase.
Figure 9.16 Calcific Tendonitis.
An AP view of the right shoulder obtained with external rotation of the humerus shows an amorphous globular calcification within the expected position of the distal supraspinatus tendon (arrow). The calcification is a focus of calcium hydroxyapatite and this patient has calcific tendinitis.
Scapular fractures may be difficult to identify on conventional radiographs. Suspected fractures should be evaluated with AP shoulder radiographs as well as a scapular Y view. Fractures of the scapula are much easier to identify on CT imaging.
Scapular fractures can be seen following traumatic injuries such as falls and motor vehicle accidents. When identified, clinicians should have a high index of suspicion for additional thoracic injuries (rib fractures, pneumothorax, lung contusion). A CT scan of the shoulder should be performed if a scapular fracture involves the glenoid. Fractures involving the articular surface of the glenoid may need surgical fixation and orthopedic consultation should be obtained. Most fractures of the scapular spine and body without glenoid involvement can be managed non-operatively with a sling with outpatient orthopedic evaluation.
Figure 9.18 Scapular Fracture.
A: An AP view of the right shoulder demonstrates a fracture extending along the superior scapula border (arrow). There is an additional fracture through the acromion as well (arrowhead). There is extensive regional soft tissue edema. B, C: An AP view of the right scapula of a different patient (B) shows subtle step-off and disruption of the “scapular X”: this may be the only sign of a nondisplaced scapular fracture extending though the scapular spine. An attempted scapular Y view (C) shows the fracture better.
Scapular fractures may be difficult to diagnose on conventional radiographs.
Non-contrasted CT imaging of the shoulder should be performed if a scapular fracture involves the articular portion of the glenoid. Factures that extend through the articular surface of the glenoid may require operative fixation.
Figure 9.19 Glenoid Neck Fracture.
AP view of the chest shows a fracture extending through the left glenoid neck. The glenoid is severed from the rest of the scapula and mildly displaced. The fracture does not extend through the glenoid articular surface, however, and the glenohumeral joint alignment is maintained. Left clavicular and left rib fractures are present as well.
Clavicle fractures can typically be identified on AP radiographs of the shoulder. Clavicle fractures can be classified as proximal, middle third, or distal. When AP radiographs do not reveal a clavicular fracture but clinical suspicion remains high, a 45° AP cepahalad view can be helpful. CT imaging may be necessary to further evaluate proximal third fractures, particularly when the sternoclavicular (SC) joint is involved.
Clavicle fractures are common and can result from direct and indirect forces applied to the shoulder. Most patients will describe point tenderness at the fracture site and will clinically have bruising and a palpable deformity. Open clavicle fractures are rare, but severe tenting of the skin can be seen in severely angulated and displaced fractures and requires emergent orthopedic evaluation. Most clavicle fractures occur in the middle third of the clavicle. Nondisplaced fractures can be treated conservatively in a sling for comfort. Communited fractures, fractures with foreshortening, and severely displaced or angulated fractures may require surgical fixation. Displaced distal clavicle fractures may indicate injury to the CC and AC ligaments and requires orthopedic follow-up. Proximal third fractures are the least common. They are often associated with severe trauma to the mediastinum and their presence should alert the physician for potential internal injury. CT imaging is usually necessary to fully evaluate the fracture pattern and SC joint involvement, as well as assess for additional trauma to the chest.
Figure 9.23 Left Clavicular Head Fracture.
A single axial CT image at the level of the clavicular heads shows a mildly comminuted fracture of the left clavicular head (arrowhead). Medial clavicular fractures are very subtle. This fracture was not visible on the conventional radiographs of the chest, even in retrospect. Look for subtle malalignment of the clavicular heads on AP views of the chest.
Clavicle fractures with associated tenting of the skin require emergent orthopedic evaluation.
The majority of clavicle fractures can be managed nonoperatively; however, severely comminuted, displaced, and angulated fractures may require surgical management.
Proximal clavicle fractures can be associated with severe intrathoracic injury. When present, clinicians should assess for additional injury by obtaining a contrasted CT scan of the chest.
SC dislocations occur when the proximal clavicle is displaced anteriorly or posteriorly at the SC joint. Sternoclavicular subluxations can be difficult or impossible to appreciate on conventional radiographs. The greater the clavicular displacement, the higher is the sensitivity of radiographs. Frank SC dislocations can be seen on AP chest radiographs by noting asymmetry in the positioning of the clavicular heads. CT imaging is the gold standard and should be performed with CT angiogram of the chest when there is clinical concern for vascular injury.
Figure 9.25 Left Sternoclavicular Dislocation.
An axial CT image at the level of the sternoclavicular joints shows abnormal widening of the left sternoclavicular joint (arrow) consistent with mild dissociation. The density surrounding this abnormal joint and extending into the anterior mediastinum is a hematoma. Notice the normal right sternoclavicular joint.
SC dislocations can occur following blunt trauma to the joint or can be seen following a fall onto the lateral shoulder. Clinically, patients will have pain, swelling, and often palpable deformity to the joint. Anterior dislocations often do not require reduction and can be treated nonoperatively. Posterior dislocations may require reduction due to impingement on the underlying vascular structures.
Reduction should not be performed in the ED due to serious risk of vascular compromise. Reductions should be performed in the operating room with orthopedics and vascular surgery readily available.
A serendipity view radiograph can be taken by directing the beam 40° cephalad on AP view. This view should include both medial clavicular heads and allows the viewer to evaluate the SC joints for subtle asymmetry.
Radial head and neck fractures can usually be seen on standard AP and lateral elbow radiographs. An elbow effusion, best seen on the lateral view (posterior fat pad elevation or anterior sail sign) should alert the clinician to the possibility of an occult fracture, if a fracture is not apparent. Radial head views (45° inferior to superior lateral elbow radiographs) are frequently helpful because the ulna no longer overlies the radius.
Nondisplaced or minimally displaced fractures (<1-2 mm of step off along the articular surface) of the radial head and neck can be placed in a sling for comfort with early active range of motion allowed, as tolerated. Patients will require close orthopedic follow-up in 1 week for repeat radiographs to ensure no additional displacement. Displaced/depressed radial head fractures with >2 mm depression should have close follow-up with orthopedics for probable surgical fixation. These patients can be managed temporarily in a sling or posterior splint.
The most common cause of a traumatic joint effusion seen on adult elbow radiographs is a radial head fracture. Patients with the presence of a posterior fat pad despite no definitive fracture should be treated for an occult radial head fracture.
A radial head view may be helpful in confirming the diagnosis. Minimally displaced fractures are frequently visible only on this view.
CT imaging can aid in assessing the amount of displacement and depression when radiographs are inconclusive.
Olecranon fractures can be identified on AP and lateral radiographs of the elbow. These can be seen in elderly patients as a result of indirect trauma resulting form the sudden pull of the triceps on its insertion, or may be associated in younger patients with blunt direct trauma to the posterior elbow after a fall.
Small avulsion fractures with intact triceps mechanism may be treated conservatively in a sling or with a posterior splint. Fractures extending past the trochlear notch, comminuted fractures, and large or displaced fractures require surgical plate fixation.
Ulnar nerve injuries can occur with olecranon fractures and should be assessed at the time of evaluation.
Open fractures should be suspected with overlying lacerations seen over the olecranon sustained after a fall with direct trauma to the posterior elbow.
Medial epicondyle avulsion fractures are a common elbow injury during adolescence occurring before fusion of the medial epicondyle ossification center. Throwing athletes will often report a sudden pop with associated pain along the medial epicondyle due to a bony avulsion injury of the ulnar collateral ligament. AP views of the elbow show displacement of the medial epicondyle ossification center. Knowledge of the expected normal order of appearance and fusion of the ossification centers at the elbow is critical in making the diagnosis (Table 9.1). It is important to realize that while the order of appearance is predictable, the exact age is somewhat variable. The ossification centers appear earlier in girls than in boys. They typically fuse between the ages of 14 and 16, except for the medial epicondyle ossification center that is the last to fuse at age 18-19. Perhaps the single most important relationship at the elbow is the order of appearance of the medial epicondyle and trochlea of the humerus: the medial epicondyle normally appears earlier than the trochlea. Therefore, it is not normal for the medial epicondyle ossification center to be absent while an ossification center is observed near the expected position of the trochlea. If this abnormal relationship is observed, an avulsion fracture of the medial epicondyle is present with the center displaced distally in the region of the trochlea. If the findings are equivocal, a comparative radiograph of the contralateral elbow should be obtained to assess for a subtle abnormality of the medial epicondyle. MRI may be helpful to evaluate injury to the ulnar collateral ligament.
| Ossification Center | Approximate Age at Which the Ossification Center Appears |
|---|---|
| C: capitellum | 1 |
| R: radial head | 3 |
| I: internal (medial) epicondyle | 5 |
| T: trochlea | 7 |
| O: olecranon | 9 |
| E: external (lateral) epicondyle | 11 |
Little league elbow is a spectrum of injuries to the medial elbow ranging from apophysitis to an avulsion fracture of the medial epicondylar ossification center. Patients will have pain on palpation of the medial epicondyle. Valgus loading of the medial elbow will also elicit pain and instability with fractures and injuries to the ulnar collateral ligament. Avulsion fractures with less than 2 mm of displacement can be treated with a sling or splint immobilization and rest for 4-6 weeks. Avulsion fractures with >2 mm of displacement may benefit from surgical fixation and require orthopedic referral.
A comparative AP view of the contralateral normal elbow may be helpful to evaluate for subtle avulsion fractures.
The medial epicondyle is the last ossification center to close (at age 18-19) and is subjected to increased valgus loads with pitching.
Little League baseball has restrictions parents and coaches should be aware of including: total pitches per game, avoidance of breaking pitches until a certain age, and games off between games pitched. Patients and parents should be reminded of these rules when presenting with these injuries.
Supracondylar fractures are the most common elbow fractures in children. They typically result from a fall onto an outstretched hand. AP and lateral radiographs of the elbow should be performed. Forearm radiographs should be obtained as well because associated forearm fractures are common. A lateral elbow radiograph will show a joint effusion presenting as an elevated posterior fat pad or anterior sail sign. Normally, the anterior humeral line (a line drawn down the anterior humerus) bisects the middle third of the capitellum. If, instead, it bisects the anterior third of the capitellum (or projects even further anteriorly), a supracondylar fracture is present. These fractures can be classified as type I, II and III. Type I fractures are nondisplaced with presence of a joint effusion; because they are nondisplaced, the anterior humeral line is normal. Type II injuries involve mild displacement with the anterior humeral line hitting the anterior third or less of the capitellum. Type III fractures are displaced with disruption of the anterior and posterior cortices of the humerus.
Supracondylar fractures are a common fracture pattern seen in younger patients following a fall onto an outstretched hand. There is a high association of brachial artery injury as well as injury to median, ulnar, and radial nerves. A thorough neurovascular exam must be performed to assess for these injuries. Type I fractures may be treated in a double sugar-tong splint or posterior splint with an A-frame with sling and orthopedic follow-up. All open fractures, fractures with neurovascular compromise, and type II and III fractures require operative fixation and emergent orthopedic consultation.
The most common cause of a traumatic effusion without radiographic evidence of fracture in a pediatric patient is an occult supracondylar fracture.
Brachial artery injuries are reported in up to 10-20% of all supracondylar fractures and are most common with type II and III fractures.
Median nerve injuries are most common with posterior and laterally displaced fractures.
Radial nerve injuries are seen in posterior and medially displaced fractures.
Ulnar nerve injuries are associated with supracondylar fractures with flexion angulation.
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