Diagnosing and Treating Clavicle Injuries
Mark R. Hutchinson, MD; Gurminder S. Ahuja, MDTHE PHYSICIAN AND SPORTSMEDICINE - VOL 24 - NO. 3 - MARCH 96
In Brief: The most common injuries to the clavicle and its associated articulations are acromioclavicular and sternoclavicular dislocations, clavicle fractures, and osteolysis and degeneration of the clavicle. Physicians need to be familiar with the anatomy of the region and the most common mechanisms of injury to be able to expediently diagnose and treat such injuries. Diagnosis is often straightforward, and conservative measures such as a figure-of-eight harness, icing, and nonsteroidal anti-inflammatory drugs usually produce satisfactory results.
The clavicle and its articulations, forming the clavicular complex, are commonly injured in sports. The number of clavicle injuries ranges from 0 to 0.23 per 1,000 athletic exposures, depending on the sport (1) (see "Clavicle Injury Risk"). (An athletic exposure is an event, game, or practice in which the athlete participates.) Sports that place participants at greater risk of clavicular complex injury include ice hockey, football, martial arts, lacrosse, gymnastics, weight lifting, wrestling, racquetball, and squash. Fortunately, most injuries can be treated symptomatically and conservatively with rest, ice, nonsteroidal anti-inflammatory drugs (NSAIDs), and a sling.
Understanding the Anatomy
Physicians need to understand the anatomy of the injured region and the mechanics of the injury to make the proper diagnosis and suggest appropriate treatment. The clavicle is an S-shaped bone that connects the shoulder girdle to the trunk. It is a rigid strut that maintains the shoulder in a functional position in relationship to the axial skeleton and allows varied hand positions in sports. The deltoid, pectoralis major, trapezius, sternocleidomastoid, and subclavius all insert or originate on the clavicle and can cause deforming forces after an injury.
In addition to its structural function, the clavicle protects major underlying neurovascular structures as they pass from the neck to the axilla. This fact is especially important because clavicle fractures—especially of the medial aspect—can compromise the costoclavicular space and injure neurovascular structures (2,3). Fortunately, clavicle injuries with associated significant neurovascular injuries are quite rare.
The clavicle articulates with the acromion to form the acromioclavicular (AC) joint and with the sternum to form the sternoclavicular (SC) joint (figure 1: not shown). The AC joint is a diarthrodial joint between the lateral end of the clavicle and the medial margin of the acromion. Several ligaments reinforce the joint capsule to maintain stability. The AC ligament and the capsule provide anterior-posterior and medial-lateral stability, while the coracoclavicular ligaments provide vertical stability. Only when the coracoclavicular ligaments are completely torn is the distal clavicle prominent in a shoulder separation.
The SC joint depends on the surrounding capsule and ligaments for stability. Ligamentous structures include the SC ligament (or capsular ligament), an intra-articular disk ligament, an interclavicular ligament, and an extra-articular costoclavicular ligament (rhomboid). The SC ligament is the strongest and most important structure preventing upward displacement of the medial clavicle (4). The costoclavicular ligament is an important stabilizer if a proximal resection is necessary.
Of particular interest is the close proximity of the great vessels and pericardial contents just posterior to the SC joint. These vessels can be compromised by a posterior SC dislocation. Also, the proximal clavicular epiphysis is the last growth plate in the body to fuse (at approximately 22 years). Therefore, many SC injuries in young athletes are probably physeal injuries.
Mechanism of Clavicle Injury
The mechanism of injury can be particularly helpful in diagnosing clavicle injuries. Any significant trauma causing elevation, depression, retraction, or anterior or posterior translation of the shoulder will transmit forces to the axial skeleton via the clavicular complex anteriorly or the periscapular muscles posteriorly. Since the clavicular complex is the more rigid of the two, failure along the clavicular complex is much more common than injury to the periscapulars.
The actual mechanism of injury can be direct or indirect (figure 2: not shown). Direct injuries are associated with contact sports and stick sports (such as football, hockey, or lacrosse) in which the athlete sustains a direct below to the clavicle (5). Fractures are the common result of direct injuries. Blows that direct a downward force at the superior aspect of the acromion may lead to AC injury or a shoulder separation.
Indirect injuries are due to falls onto the outstretched arm or onto the lateral border of the shoulder. Fractures of the middle third of the clavicle are most frequently seen in falls onto outstretched arms, while fractures of the distal third are most often associated with loads transmitted to the lateral border of the shoulder (6). If an athlete falls or is hit on the lateral border of the acromion, the force is transmitted first to the site of impact, then to the AC joint, then to the clavicle, and then to the SC joint. Failure can occur at any one of these sites.
Making the Diagnosis
Most clavicular complex injuries are readily apparent, and making the diagnosis in an athlete is much the same as in nonathletes. Since the clavicle is just under the skin, the patient typically can identify the site of pain easily, and the deformity is usually easily seen. Patients often hold the injured shoulder and arm close to the body and support the arm.
A thorough history and physical examination can help rule out any associated injuries, such as rib and other fractures, pulmonary contusion or pneumothorax, brachial plexus injuries, vascular injuries, and compromise of the great vessels caused by posterior SC dislocation (3).
Ideally, the physical exam begins with both of the patient's shoulders exposed; however, a cursory examination and palpation can be performed on the field even underneath a football player's shoulder pads. Careful palpation along the entire clavicular complex can identify focal tenderness at the AC joint, SC joint, or fracture site. Pressure along the clavicle may reveal fracture motion or crepitus at a fracture site.
Because of pain, a patient's range of motion and strength are usually guarded with any injury to the clavicular complex. Careful, passive range-of-motion maneuvers should, however, reveal full range of motion, and motor strength should be intact to resistance. If motion or motor strength is limited, a humeral fracture, shoulder dislocation, or muscle tear might be present.
Crossing the arm on the injured side over the chest is particularly likely to exacerbate pain caused by an injury in the clavicular complex. Caudad traction of the extremity will also exacerbate pain stemming from a clavicle fracture or AC separation. Such traction can also magnify an AC separation and make it easier to visualize. Finally, no shoulder examination is complete without assessing the athlete's neurovascular status and cervical spine.
Radiographic studies confirm the diagnosis. For clavicle fractures, an anteroposterior (AP) view of the shoulder, including the entire clavicle, is usually adequate to assess angulation and displacement. An axillary view or oblique views should always be obtained to offer a second view as well as to assess for associated injuries. For AC injuries, comparison views of the opposite side are indicated. If the disruption of the AC joint is not visualized on the standard AP views, an AP stress view can be taken after suspending weights from the patient's wrists (figure 3: not shown).
SC injuries are difficult to discern with standard radiographs. Careful evaluation of the AP view may show bone asymmetry or overlap of the proximal clavicle compared with the opposite side. However, a "serendipity" view (40° cephalad) can help in visualizing anterior or posterior displacement of the proximal clavicle (6). Computed tomography, though, is perhaps the best technique to evaluate the SC joint as well as associated fractures and mediastinal involvement, and should be ordered if an acute fracture or dislocation is suspected.
Common Injuries and Treatment
Clavicle fractures. Clavicle fractures are classified by the location of the fracture (middle, distal, or proximal thirds) and further described by the amount of angulation, comminution, and displacement at the fracture site. Most clavicle fractures associated with athletic activities are caused by relatively low-energy impact and have little comminution (figure 4). During clavicle displacement, the proximal segment is drawn superiorly by the sternocleidomastoid muscle, while the distal segment droops inferiorly from the force of gravity and the pull of the pectoralis major. Occasionally, the fracture may be significantly angulated, thereby tenting the skin superiorly, compromising the neurovascular structures inferiorly, or even puncturing a lung.
Nondisplaced or minimally displaced fractures of the medial clavicle or midclavicle can be treated symptomatically with a sling or a figure-of-eight harness for 4 to 6 weeks in young adults and 6 weeks or longer in adults. Andersen et al (7) found no difference in healing, functional, or cosmetic results whether a sling or figure-of-eight harness was used.
Nondisplaced fractures of the distal clavicle are best treated with a sling and early rehabilitation. A standard figure-of-eight harness often lies directly over the distal fracture and thus exacerbates the pain. A modified figure-of-eight harness with increased padding in conjunction with a sling may be effective, but if significant displacement persists, open reduction and internal fixation may be indicated.
For moderately displaced midshaft fractures with no neurovascular compromise and no violation of skin, a figure-of-eight harness serves to reduce the fracture by longitudinal traction.
Young and Rockwood (8) recommend open reduction for any fracture site if complete displacement persists for longer than 3 weeks of figure-of-eight splinting. They further recommend primary open reduction and fixation if the patient has severe skin tenting, a failed closed reduction, or neurovascular injury. However, nonunion of fractures is significantly more common with open than with closed treatment (6).
Athletes should not be allowed to return to play until the fracture is clinically and radiographically healed. Noncontact and throwing athletes should have a full, painless range of motion and at least 90% strength compared with the uninvolved arm. Contact sports should be avoided for 4 to 6 months.
Acromioclavicular injuries. AC injuries are classified by the severity of ligament injury. Type 1 injuries consist of a mild sprain of the AC ligament and are treated conservatively with ice, a sling for comfort, early motion, and NSAIDs. Athletes can return to play when they have no pain and a full range of motion (2 to 3 weeks).
Type 2 injuries involve a complete tear of the AC ligament and a mild sprain of the costoclavicular ligament. Radiographic evaluation will show minimal displacement at the AC joint and no separation of the costoclavicular space. Since the AC joint remains stable, treatment is conservative, the same as for type 1 injuries.
Type 3 injuries consist of a complete AC dislocation with complete tears of the costoclavicular and AC ligaments (figure 3b: not shown). Treatment is based on the severity of associated injury. If the distal clavicle is completely displaced superiorly, the deltoid and trapezoid insertions may be avulsed and require surgical repair. If the distal clavicle is dislocated inferiorly below the coracoid, surgical repair is also indicated. Fortunately, these injury types are rare, and most type 3 AC injuries can be treated conservatively with 90% to 100% satisfactory results (9). Return to sports, however, may take as long as 10 to 12 weeks.
Sternoclavicular injuries. SC injuries occur once for every five AC injuries reported (10). Like AC injuries, SC injuries can be classified into three types, with type 1 being a mild sprain, type 2 a moderate sprain, and type 3 a complete dislocation. Dislocations are classified as anterior or posterior, depending on whether the medial clavicle is anterior or posterior to the sternum. Anterior dislocations are much more common. Associated injuries must be ruled out.
For type 1 and 2 injuries, treatment is symptomatic and conservative. A sling or figure-of-eight harness can reduce stresses on the SC joint and prevent subluxation. After 7 to 10 days, range-of-motion exercise is initiated (10). Return to sport is allowed when the athlete has no pain and full range of motion and can perform sport-specific movements without limitation.
Type 3 injuries warrant closed reduction. Anterior dislocations can be easily reduced with the patient supine and a rolled towel placed between the scapulae. Traction and abduction on the arm with direct pressure on the clavicle will generally reduce the dislocation. The reduction is often unstable, but an anterior dislocation can be left unreduced after an initial attempt with little functional deficit.
Posterior dislocations are worrisome because they can cause shortness of breath, dysphagia, and pressure on the great vessels. If the patient is skeletally mature, closed reduction should be attempted in the operating room under regional or general anesthesia. Occasionally, conversion to an anterior dislocation is the treatment of choice. If that fails, open reduction may be indicated. In patients who have an open proximal physis (those younger than 22 years), surgery may not be needed because of bony remodeling potential. Following reduction, a figure-of-eight splint is used to allow healing of the ligaments.
Clavicular osteolysis or degeneration. Long-term, repetitive, medial forces can lead to chronic changes at the AC or SC joint. The most common changes are degenerative. The athlete will usually complain of pain at the AC joint or distal clavicle but may not remember a specific traumatic event. The pain is usually exacerbated by crossing the upper extremity over the chest, overhead activities, or "locking out" a bench press when the arms are fully extended over the body. Radiographic studies show joint-space narrowing, sclerosis, degenerative cysts, and osteophyte formation. AC involvement is much more common than SC involvement.
Osteolysis is characterized by symptomatic resorption of bone over weeks to many months. A single traumatic event or repeated microtrauma may precipitate the condition (11). It seems to be linked with sports that require repeated shoulder-to-shoulder or shoulder-to-wall impact, such as rugby, hockey, football, ice hockey, racquetball, or handball. Cyclists who have fallen onto the point of the shoulder and have developed osteolysis have also been reported. Cahill (12) noted that most of his cases were associated with weight lifting.
Initial treatment is conservative, consisting of rest, ice, and NSAIDs. Steroid injections are of debatable benefit. Ultimately, after 3 to 4 months of failed conservative treatment, resistant cases may require excision of the proximal or distal clavicle.
Optimal treatment of clavicle injuries stems from accurate diagnosis based on knowledge of the anatomy of the region and the biomechanics of injury. Fortunately, conservative treatment of these injuries usually leads to an excellent prognosis and ultimately a full return to sports.
Clavicle Injury Risk
Most sports place high demands on the upper extremity, but some place the upper extremity and the clavicular complex at greater risk through contact or overuse. While the most common cause of sternoclavicular (SC) injury is automobile accidents (47%), athletic injuries account for a sizable portion (31%) (1).
The intensity of the activity may also play a role. Acromioclavicular (AC) injuries are commonly associated with athletic activity and are about 5 times more common in males than females (2,3). This propensity could be due to personal intensity or to the type of sport. In the only four dual-gender sports in the National Collegiate Athletic Association (NCAA) Surveillance System, men have a higher incidence of clavicle injuries than women in basketball, gymnastics, lacrosse, and soccer (4). Men and boys under 25 sustain most clavicle fractures, which occur in about 1 of every 1,000 people in the general population per year (4). The higher rate among young males is probably due to more exposure to high-risk activities.
Of the 14 sports surveyed by the NCAA, the stick sports of ice hockey and men's lacrosse have the greatest risk of clavicle injury (table A). The contact sports of football, spring football, ice hockey, and wrestling are among the six sports with the highest rates of clavicle injuries.
Ice hockey—with its repeated checking and shoulder impact into the boards—has a relatively high rate of clavicular complex injuries. Osteolysis of the distal clavicle is common in hockey players: 46% of professional athletes have radiographic abnormalities of the clavicle (5). "Gymnast's shoulder" is a degenerative process associated with prolonged participation in gymnastics and includes components of AC degenerative disease and osteochondral loose bodies.
Other sports that are not surveyed by the NCAA also place participants at increased risk of clavicular complex injury. Weight lifters have an increased incidence of both proximal and distal clavicle osteolysis. This is probably due to the repetitive stresses of "locking out" weights anteriorly in the bench press as the arms are fully extended over the body, which causes impaction forces at the AC and SC joints. Some martial arts also have high incidence of clavicular complex injury: 44% of injuries in judo are to the shoulder, and the shoulder roll in aikido is associated with AC joint separations (2).
Dr Hutchinson is an assistant professor of orthopedics, the director of sports medicine services, and the team physician at the University of Illinois at Chicago. He is also a team physician for the Chicago Cheetahs professional roller hockey team and president of the Chicago Sports Medicine Society. Dr Ahuja is a fellow in sports medicine at the Kentucky Sports Medicine Clinic in Lexington. Address correspondence to Mark R. Hutchinson, MD, College of Medicine, Dept of Orthopaedics (M/C 844), 209 Medical Sciences South, 901 S Wolcott Ave, Chicago, IL 60612-7342.