The Deceptive Nature of Clavicle Fractures in Young Patients
Megan Schimpf; Carlos Neira, MD; Edward G. McFarland, MD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 27 - NO. 3 - MARCH 1999
In Brief: A shoulder injury that would cause an acromioclavicular (AC) separation in an adult generally causes a clavicle fracture in a young patient. As illustrated in a case report, the two injuries can look similar on a standard x-ray. Conservative treatment and prognosis for both clavicle fractures and AC separations are similar, but because some AC separations require surgical repair, accurate diagnosis is important. This can be done by obtaining x-rays at one-half of the standard exposure, including AP views with 10° to 15° of cephalic tilt. Spot or cone-down views and comparison views are also helpful.
Although the clavicle is the most frequently broken bone in children and adolescents, these injuries are commonly misdiagnosed as acromioclavicular (AC) dislocations (1,2). Eidman et al (3) demonstrated that of 25 patients under the age of 13 who had fractures of the distal clavicle, 20% (5) were initially diagnosed as having AC joint dislocations. Because of the weakness of the distal (lateral) clavicular physis, complete AC separations are rare in those younger than 16 years old (1,4). In a young patient, like the one described in the following case report, an apparent AC separation is more often a clavicle fracture with intact coracoclavicular ligaments and rupture of the end of the metaphysis through the periosteum (1).
A 14-year-old high-school freshman injured his right (dominant) shoulder during wrestling practice when he was driven to the mat by an opponent and received a blow on the top of his shoulder. He stopped wrestling immediately because of the pain. Later that night he went to the hospital emergency department with a swollen, sore shoulder.
Following physical and radiographic examination, the emergency department physician diagnosed a right AC separation. A radiologist later read the films as normal. The patient was treated with a nonsteroidal anti-inflammatory drug, ice, and a sling and released. He missed 1 day of school.
He saw his primary care physician 9 days after the injury, and was referred to our office. When evaluated by us 13 days after the injury, he reported gradually decreasing pain since the incident.
Physical exam. On physical examination, he had obvious swelling and deformity at the AC joint (figure 1). Tenderness on palpation was centered over the AC joint, and he had resolving ecchymosis about his shoulder and distal clavicle. Active movement beyond 90° of elevation increased his pain.
He was neurologically intact and had normal, congruent glenohumeral joint motion and no abnormalities at the sternoclavicular joint.
Diagnosis and treatment. Radiographs obtained at our office 13 days after the injury showed a fracture of the distal clavicle with possible comminution of the metaphysis (figure 2). Superior translation of the right lateral clavicle compared to the left clavicle was apparent.
The patient was given a sling for comfort but allowed motion as tolerated. He was told to ice the fracture if sore and was urged not to risk reinjuring his shoulder.
Follow-up. Four weeks after the injury he had nearly full range of shoulder motion. By 2 months postinjury he had no pain and had started doing push-ups and some wrestling drills and exercises. On examination he had full range of motion, normal strength, no tenderness at the fracture site, and no pain with a crossed-arm adduction stress test. Radiographs showed blurring of the original fracture line with periosteal elevation and callus formation consistent with new periosteal formation. A bubble-like callus surrounded the entire bone, supporting the diagnosis of sleeve fracture vs a shaft fracture (figure 3). He was cleared for a gradual return to sports, guided by his pain level.
Two days after his visit, the patient was once again thrown to the mat in a wrestling match and immediately felt pain. He stopped wrestling after the incident and did not return for the rest of the season.
When he returned to our office about 4 months after the original injury, he was pain-free and had a normal residual deformity at the AC joint. The physis had reconstituted and the callus was progressing at a rate consistent with healing. He subsequently returned to sports with no limitations.
Mechanisms of Injury
Either a clavicle fracture or an AC joint injury can occur with shoulder trauma in sports such as football, hockey, karate, and lacrosse. Eidman et al (3) reported that of 25 patients who had either problem, 80% (20) were playing a sport at the time of the injury.
Though the usual mechanism of clavicle fracture is thought to be a fall on an outstretched hand (6), Stanley et al (6), in a series of 150 patients who had clavicle fractures, found that almost all of the distal clavicle fractures (34 of 36) resulted from a direct blow to or a fall on the shoulder. AC joint dislocations can also result from falls on the shoulder, which drive the scapula and upper extremity inferiorly (1,2,5,7). AC dislocations are more likely in adults; distal clavicle fractures are more likely in children.
Fracture Patterns in the Young
The clavicle is the first bone to ossify but the last to fuse at its epiphyses. The secondary ossification center in the lateral clavicle (figure 4a), which is responsible for only 20% to 30% of longitudinal growth of the clavicle, remains cartilaginous until age 19 and possibly later (4,5,8).
Because the physeal-metaphyseal junction is the weakest point in the bone, the risk of fracture is higher than the risk of AC separation until the ends completely fuse (3,4). One study (4) found evidence in some patients that distal secondary ossification and fusion never occurred.
The clavicle's periosteal sleeve provides attachment for the coracoclavicular ligament and the AC ligament. In young patients, as with the wrestler in our case report, a fracture of the lateral metaphysis commonly ruptures the periosteal sleeve surrounding the bone; because the cartilaginous epiphysis is still in place in the sleeve and cannot be seen on a radiograph, it can be mistaken for increased space in the AC joint. These fractures resemble Salter-Harris type 1 injuries (which follow the line of the physis) or type 2 (which run along the physis and through the metaphysis) (2).
The standard classifications of clavicle fractures by Allman group both adults' and children's fractures by location and severity (5). Group 1 fractures involve the bone's middle third and represent 80% of all clavicle fractures. Group 3 includes fractures of the proximal third of the clavicle, which are seen in 5% of cases.
Fractures of the distal third, group 2, constitute the remaining 15% of clavicle fractures, and have been subdivided into five categories by Craig (figures 4b and 4c) (5). Type 1 involves minimal displacement and intact ligament structure. Type 2 involves displacement of the clavicle secondary to a fracture occurring medial to the coracoclavicular ligaments, in which the conoid portion may be attached to the distal bone fragment or torn. Type 3 fractures involve the AC articular surface without further ligament injury. With type 4 fractures, the fracture follows the line of the physis, and the ligaments are intact to the periosteum with displacement of the proximal portion. Type 4 injuries, which our patient had and which are most commonly seen in patients younger than 16, are also called pseudodislocations (1,4) and may mimic an AC separation (figure 4d). Because the periosteum is disrupted, the proximal portion can rupture through it while the coracoclavicular ligaments are still attached to the periosteum (1). Type 5 fractures are comminuted with fragments completely detached from the ligaments (5).
With any clavicle fracture or AC injury, the patient usually presents with the affected arm supported or held straight against the side. Pain and swelling are typically noted over the area of the AC joint and along the distal end of the clavicle. Neurovascular disturbances are rare with these injuries, although brachial plexus or subclavian artery damage should be ruled out (9). Crepitus is frequently noted on movement (5). Patients who have AC joint sprains and dislocations initially present with painful and limited range of motion, especially in horizontal adduction and full elevation. Patients usually have pain on palpation around the AC joint and the distal clavicle region.
Radiographic diagnosis. Because standard radiographs may not show a fracture, one-half of the standard exposure should be used to obtain optimal radiographic films for all views of the AC joint area. An anteroposterior view with 10° to 15° of cephalic tilt should be obtained (1,10). Comparison views of the opposite shoulder are also helpful in evaluating the AC joint. Spot views, or cone-down views, of both AC joints often give more detail and better resolution than standard shoulder views.
Stress views have no place in evaluation of distal clavicle injuries in children and youth because they do not change the management of the fracture.
Since distal clavicle fractures in young patients may be mistaken for AC dislocations, it is fortunate that the management is much the same in either case. However, differentiating the two may be important because, rarely, AC separations require surgical repair.
Nonsurgical treatment for distal clavicle fractures is nearly unanimously indicated in the literature (1,2,8). Eidman et al (3), who performed surgery on some children with distal clavicle fractures, concluded that equivalent results would have been achieved with nonoperative treatment, resulting in less expense, risk, and effort.
Rest, ice, and immobilization in a sling are indicated in almost all distal clavicle fractures, including those requiring reduction (1,2,4,9). Nonunion is rare, even in displaced fractures in adolescents (2,3,8,11). Callus formation, which may cause a palpable or even visible protuberance, usually regresses with maturation (9).
While a figure-eight splint may be used in young children with midshaft or medial clavicle fractures, it is contraindicated for distal clavicle fractures. Because of the difficulty of effectively stabilizing a distal clavicle fracture with a figure-eight splint, a sling is preferable.
Healing for a distal clavicle fracture usually requires about 6 to 8 weeks of immobilization (1,9). Craig (1) recommends rest from sports activity in teenagers for 4 additional weeks until optimal bone strength has been regained, and recommends keeping teens out of competition for 12 to 16 weeks. Compliance questions can arise with a long course of restrictive treatment, especially in this age-group; accordingly, Webb and Mooney (8) recommend a less restrictive course with use of a sling for 3 to 4 weeks followed by a gradual increase of functional exercises as pain allows. As treatment progresses, growth at the lateral clavicular physis should be monitored.
For young patients with distal clavicle fractures, operative treatment is indicated only in the rare case of an open fracture, an unstable fracture with accompanying neurovascular injury, a prominent irreducible subcutaneous fracture, or painful nonunion (2,8).
A Positive Projection
As is the case with many childhood injuries, the prognosis for young patients who have distal clavicle fractures or AC joint injuries is excellent. Most of these patients show no abnormalities in growth or function over time (2,8). A complete return to activity without pain or deformity should be expected in almost all patients, and surgery is rarely indicated.
Ms Schimpf is a medical student at the University of Michigan Medical School in Ann Arbor. Dr Neira is a research fellow and Dr McFarland is director, both in the section of sports medicine and shoulder surgery in the department of orthopedic surgery at the Johns Hopkins School of Medicine in Baltimore. Dr McFarland is a member of the editorial board of The Physician and Sportsmedicine. Address correspondence to Edward G. McFarland, MD, Dept of Orthopaedic Surgery, Section of Sports Medicine, 10753 Falls Rd, Suite 215, Lutherville, MD 21093.