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Clavicular shaft fractures

Description

Clavicular shaft fracture commonly occur in young adults due to falls with the arm at the side or direct blow to the shoulder, and the majority can be treated non-operatively with a sling.

Structure and function

The clavicle is an S-shaped bone with a cephalad caudad curvature.  Its integrity effects the entire shoulder girdle because it acts as a strut which stabilizes the scapula and glenoid and allows  transfer of power from the trunk to the arm (7). The clavicle is involved in 2 (sternoclavicular and acromioclavicular) out of the 4 joints (scapulothoraric and glenohumeral) that make up the closed chain mechanism of the shoulder(5).

The midshaft is the thinnest segment of the clavicle with no stabilization from ligaments, thus making it most vulnearable to fracture.

Muscle attachments on the medial side include the sternocleidomastoid while the deltoid and pectoralis major muscle attach on the later side (5).  These muscle attachments are important for midshaft fractures because they produce the opposing forces pulling on the clavicle to cause displacement. |
PMID: 18236824

Epidemiology

Clavicle fractures represent up to 4% of all adult fractures (1).  More specifically, they also are 35% of the injuries to the shoulder girdle.  In the clavicle, shaft fractures are the most common type of injury occurring about 80% of the time compared to lateral-end and medial-end injuries (1). 

The largest peak incidence for these fractures is in males <30 years of age as a result of direct forces from various sporting activities.  The second incidence peak occurs in elderly female population due to osteoporosis and low-energy domestic falls.  In these cases, the incidence of lateral and medial-end fractures is increases (1) |


Clinical presentation

The most common mechanism is a fall or direct blow to the shoulder resulting in axial compression force on the clavicle to cause a fracture.  The patient often hold the affected arm adducted close to the body and supported by the opposite hand (8). 

On exam, a defect or visible deformity might be visible.  In addition, ecchymosis, edema, focal tenderness, or crepitation on palpation can be present (8).

A visible deformity might suggest a displacement of lateral fragment downward under the weight of the shoulder and rotated by the pull of the pectoral major and trapezius muscles (7). The unopposed medial fragment gets pulls upward and posteriorly by the sternocleidomastoid muscle (1).


Red flags

In cases of high-velocity trauma, suggested by clinical history or evidence of multiple rib fracture, make sure to evaluate for chest injury like pneumothorax or hemothorax.

In the instance of medial-end fractures, be sure to evaluate for posterior displacement. This can result in compression of mediastinum and major vessels to the heart thus requiring urgent operative intervention.

In children or adults with clavicle fractures, if no history of trauma is reported then be sure to consider physical abuse, malignancy or rickets (8).


Differential diagnosis

A clavicular shaft fracture must be suspected in all individuals that sustained trauma to the shoulder.  Usually a visible deformity and pain with palpation is present.  It is important to examine the skin to exclude open fracture since there is little soft tissue between the skin and the bone.

It is important to also consider the neurovascular status of the effected arm.  Injuries to the brachial plexus or the subclavian vessels can occur due to their proximity.  Superficially, difference in blood pressure between the arms can suggest vascular injury but duplex scanning or arteriography is needed to confirm the high suspicion.

Lastly, the lung examination is important in the assessment because posterior displacement of the fracture fragments can cause injury to the lung apex resulting in a pneumothorax or hemothorax.


Objective evidence

If a clavicle fracture is suspected based on history and physical exam, then a single anteroposterior (AP) plain film view is needed initially. It is also possible to get a 15 degree PA view to assess for shortening.  Furthermore, more detail can be obtain with a apical oblique image (10).  For best assessment of displacement, a spiral CT w/ 3D reformatted views is helpful.  CT is rarely indicated for midshaft fractures but is especially critical for medial-end fractures to determine any injury to vascular structures.

Examination of the x-rays for location relative to the coracoclavicular ligament is important.   Stress views to assess its integrity  are helpful if there is concern for injury to the AC joint but are painful for the patient and rarely affect management.

Evaluation of the x-ray will help classify the fracture based on the Edinburgh classification system, which is most commonly used as it considers the presence of displacement and degree of comminution to help aid treatment decisions and prognosis (2).  Fractures of the shaft are type 2, with an A or B designation to represent absence or presence of displacement, respectively.  Type 1 fractures are of the medial fifth and type 3 are of the lateral fifth clavicle segment.

Prognostically, evidence of shortening of >15 mm has been associated with increased incidence of pain after osseous healing (8).

If a vascular injury is suspected by noting difference in blood pressure between the two upper extremities, a duplex scan or arteriography is indicated.


Risk factors and prevention

Since clavicular shaft fractures most commonly occur due to falls or direct trauma, there is no specific way to prevent them.  Caution is advices along with protective padding when involved in contact sports. 




Treatment options

The decision for treatment options is based on the type of clavicular fracture based on the Edinburgh classification system.  The focus will be on the most common clavicular fracture, an Edinburgh type 2 shaft fracture.  Treatment options differ for type 1 medial end and type 3 lateral end fractures.

Type 2A are undisplaced midshaft clavicular fractures. These are treated non-operatively in either a sling or figure-of-eight bandage.  The sling is the preferred treatment option because recent studies have shown that the figure-of-eight bandage has increased risk of axillary pressure sores, compression of neurovascular bundle and non-union (3).

Type 2B are displaced midshaft clavicular fractures. There treatment is more controversial. Early studies suggested that non-operative treatment was also indicated as non-union rates were <1% (1). However, patient selection in those studies included pediatric patients; thus newer studies looking at displaced midshaft fractures in adults site show about 15 to 20% of non-union and 25% of symptomatic malunion with non-operative treatment (6). As a result, it has been suggested that these fractures benefit from operative treatment, especially if shortening of <15 mm is present (12).  There is still much debate about the standard of care for type 2B fractures, and it is important to discuss the risk of either treatment with the patient.

Surgical options for type 2B include most commonly plate and screw fixation, and less used intramedullary fixation and external fixation (11).  Platting has been shown to provide better functional outcomes and lower rates of malunion/ non-union but high complication and reoperation rate of about 18% (6).

Open fractures and any neurovascular compromise are indications for surgery and open reduction and internal fixation (12).

Physical therapy plays an important role as early range of motion exercise as pain decreases improve patient outcomes.

Salvage treatment for symptomatic malunions after non-operative treatment would require a correction osteotomy (5).

Return to contact activities is usually allowed by 3 months if satisfactory healing is visible on radiographs (11).


Figure 2. Edinburgh Classification System
PMID: 9619941

Outcomes

For the nondisplaced clavicular shaft fractures, the non-union rate is <1%.  However, new studies show that for adults with displaced shaft fractures, the non-union is higher up to 20%.  The risk for non-union is increased with increasing age, female gender, degree of displacement and comminution.

It is important to note that some degree of malunion is expected with all displaced clavicular fractures treated non-operatively.  This may be asymptomatic or can result in pain and  clicking sensation with movement.

In children, most shaft fractures heal well non-operatively, but it is important that parents are not alarmed as kids can form significant callus during the healing process (8).

For refractures, non-union is relatively common and internal fixation is required.

Surgical approach requires caution to avoid intraoperative injury to the subclavian artery or vein at the time of fracture mobilization due to their proximity to the clavicle.

Holistic medicine

Because clavicular injuries effect the shoulder mechanism, they can impact functional activities of daily living like dressing and cleaning.


Miscellany

Other used classifications include the Allman and Neer systems.

A unique entity related to clavicular fractures is a floating shoulder.  This involves an ipsilateral scapular neck and clavicular shaft fractures that disrupt the shoulder girdle mechanism. This is very rare and usually results from high energy trauma (4). It is important to suspect brachial plexus injury in these patients.

Surgical treatment of the clavicle requires careful soft tissue management to avoid supraclavicular nerve damage that gives sensitivity to the overlying skin (7).

Future studies on clavicular shaft fractures will require randomized control trials to settle the debate if operative treatment is the standard of care for displaced shaft fracture in adults. 

The clavicle is a unique bone that ossifies first in the human body after the 5th month of fetal development (7).  This ossification also occurs by intramembranous ossification in contrast to most other process of endochondral ossification for long bones (7). Also, it is one of the last bones to fuse as fusion of the sternal or medial end occurs in the early third decade (9).

Perinatal fracture of the clavicle from birth trauma have an incidence of 3-7 per 1000 births and most often heal spontaneously and require to surgery (12). This most commonly is related to shoulder dystocia.
 
In birds, the clavicles are called the “wishbone”.



Key terms

Clavicle, Midshaft, Diaphyseal, Fracture, Collar bone


Skills

Recognize on upper extremity neurovascular exam, injuries to brachial plexus, peripheral nerves, and major blood vessels.

Be able to correctly interpret chest plain films and dedicated clavicle films for fracture pattern and relation to medial and lateral ends.

Be able to apply a shoulder sling for temporary or definitive treatment for isolated clavicular fractures.Appreciate that surgical treatment requires understanding and incision along the Langer lines of skin across the clavicle.

Ref:

1) PMID: 19181992

2) PMID: 9619941

3) PMID: 3554886

4) PMID: 15964570

5) PMID: 20367423

6) PMID: 20399361

7) PMID: 18989685

8) PMID: 18236824

9) PMID: 19302058

10) PMID: 3495969

11) PMID: 19302058

12) PMID: 21888838

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