Clavicle
Relevant Anatomy
The clavicle, or collar bone, is an S -shaped bone anterior to the base of the neck. Through articulations with the sternum medially and with the scapula at the acromion process laterally, it serves as an osseous connection between the axial skeleton and the upper extremity. In cross section, the medial portion of the clavicle is rounded or prismatic, and the lateral third is flattened. The entire anterosuperior aspect of the clavicle is subcutaneous without significant muscular coverage.
The clavicle acts as an origin for the pectoralis major on the medial two thirds of its anterior surface and for the deltoid on the lateral third of its anterior surface. Inferiorly, through its middle third, it affords an attachment for the subclavius muscle and its enveloping clavipectoral fascia while providing an attachment for both portions of the coracoclavicular ligament and the acromioclavicular ligament laterally and for the costoclavicular ligament medially. Posteriorly, the clavicle provides an attachment in its lateral third for the trapezius and for the clavicular head of the sternocleidomastoid muscle medially. The subclavian vessels and brachial plexus lie posterior to the junction of the medial two thirds and the lateral one third of the bone.
Developmental Anatomy
The clavicle is the first bone to begin ossification, which occurs from two primary centers that appear during the fifth or sixth week of fetal life. In contradistinction, it is one of the last to completely ossify because its medial physis does not close completely until 24 to 26 years of age in many men.
Medial Clavicular Fractures and Pseudosternoclavicular Joint Dislocations
Incidence
A fracture of the medial portion of the clavicle occurs infrequently in children and accounts for only about 5% of all pediatric clavicular fractures. Medial physeal fractures are more common than medial shaft fractures, and the former can mimic sternoclavicular joint dislocations.
Mechanism
The capsule of the sternoclavicular joint is more resistant to injury than is the physis of the medial portion of the clavicle. Because the physeal plate remains open until well into the young adult years, forces in children and adolescents usually produce a physeal injury rather than an actual dislocation of the sternoclavicular joint. The most common mechanism of injury is axial compression of the shoulder toward the midline. Whether displacement of the lateral fragment occurs anterior or posterior to the sternum is determined by the secondary force vectors of this axial compression. A direct anterior-to-posterior force can generate a fracture or dislocation of the medial segment of the clavicle; in such a case, displacement is always posterior.
Diagnosis
The patient usually is seen with a history of either a blow to the medial part of the clavicle or the sternal area or, more commonly, after a direct axial compression through the shoulder. Physical examination reveals local swelling and tenderness about the medial part of the clavicle ( Fig. 11-1 ). Anterior displacement presents with an obvious prominence in this area. When the displacement is posterior, symptoms of respiratory embarrassment, dysphagia, dysphonia, or distended neck veins from compression of the neighboring trachea, esophagus, recurrent laryngeal nerve, or great vessels may be present, although in some cases no secondary problems or symptoms exist. Radiographs angled to minimize the effect of obscuring overlying tissues—for example, the “serendipity” view of Rockwood ( Fig. 11-2 ) or the Hobbs view, with the medial part of the clavicle and the sternoclavicular joints visualized bilaterally for comparison—usually confirm the diagnosis. However, computed tomography (CT) of the sternoclavicular joint is the most useful imaging modality because it clearly delineates the direction and extent of displacement, as well as the relationship of the displaced clavicular fragment to neighboring structures ( Fig. 11-3 ). Ultrasound has also been used to assess this fracture.
Treatment
Nonoperative
Nondisplaced fractures of the medial portion of the clavicle can be managed symptomatically and have a good prognosis. A “bump” secondary to new callus should be expected and remodels to some extent with time, especially in a younger child. In many cases, anteriorly displaced fractures require little treatment. Closed reduction can be attempted with longitudinal traction and direct pressure over the fracture. Usually, reduction is easily obtained but difficult to maintain, and redisplacement is a common result. If reduction fails or redisplacement occurs, further intervention is rarely indicated. Some remodeling may be expected, and little, if any, morbidity is noted beyond a minor cosmetic defect from the residual prominence. However, some patients may be seen with persistent pain and instability after an anterior fracture or dislocation. In these cases, surgical management may be required. Respiratory distress secondary to a posteriorly displaced medial clavicular fracture may be life-threatening, and an adequate airway should be secured as part of the patient’s initial treatment. A posteriorly displaced medial clavicular fracture can sometimes be reduced by drawing the patient’s shoulder posteriorly and into abduction; this maneuver is facilitated by placing the patient supine with a folded towel or another type of bump placed between the scapulae to abduct the shoulder girdles. In addition, longitudinal traction on the involved upper extremity may assist in the reduction. Posteriorly displaced fractures that fail to reduce with closed techniques may be amenable to percutaneous reduction. After suitable anesthesia and skin preparation, a sterile towel clip is used to control the medial part of the clavicular shaft and manipulate it to its reduced position. A thoracic or cardiac surgeon should be available for potential assistance when such a reduction maneuver is undertaken, particularly in those cases with evidence of preoperative respiratory or vascular compromise.
Maintenance of closed reduction is more common if the initial displacement is posterior. The displacing forces can be minimized successfully with a figure-of-8 strap and an arm sling. Such immobilization should be maintained for approximately 4 weeks. The medial clavicular physis has great remodeling capacity, and late pain and deformity are rarely seen after displaced medial clavicular fractures.
Operative
Primary open reduction should be reserved for open injuries requiring débridement, for posteriorly displaced fractures that adversely affect neighboring vital structures and that have failed to be reduced by percutaneous methods, and for significant anterior displacements that cannot be reduced (and maintained) by closed techniques. Internal fixation with Kirschner wires or smooth pins is inadvisable and has been associated with potentially grave complications. Alternatively, sutures placed strategically through drill holes in the outer portion of the neighboring sternum or sternoclavicular ligament and the medial section of the clavicle should suffice to stabilize the reduction. Waters and colleagues demonstrated good results with a suturing technique using nonabsorbable suture, and Goldfarb and colleagues reported success with a figure-of-8 sternal wire after open reduction of posterior dislocations that had failed closed manipulation. Delayed operative reconstruction may be necessary in patients with pain and instability secondary to a residual anteriorly displaced injury. Fixation methods, including reduction and suture techniques, are similar to those used in primary procedures. One additional, albeit rare, indication for open reduction is scapulothoracic dissociation. In this situation, anatomic reduction with soft tissue direct repair helps “set” the scapula and clavicle in the correct position on the thoracic wall and facilitates healing of the torn scapular suspensory musculature approximating correct resting length.
Perinatal Clavicular Shaft Fractures
Incidence
The clavicle is the most commonly fractured bone in the newborn. The incidence of birth fractures involving the clavicle ranges from 2.8 to 7.2 per 1000 term deliveries, and clavicular fractures account for 84% to 92% of all obstetric fractures. ∗
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Mechanism and Diagnosis
Clavicular injury at birth has been shown to correlate with increased birth weight of the infant, lower head-to-abdominal circumference ratio of the infant, inexperience of the delivering physician, and forceps delivery. In the vast majority of cases, the mechanism of fracture production is indirect due to axial compression of the shoulder girdle during passage through the birth canal. The most common fracture site is at the junction of the lateral and middle thirds of the bone. The fracture is usually nondisplaced or only minimally displaced; often, it is unappreciated clinically and then discovered as a prominence over the shaft of the clavicle 7 to 10 days after birth. Plain radiographic results may be negative initially but generally demonstrate periosteal reaction 7 to 14 days later. Kayser and associates described using ultrasound to image suspected neonatal clavicular fractures with excellent success. Occasionally, the fracture is manifested by pseudoparalysis of the arm ( Fig. 11-4 ). In this instance, the differential diagnosis includes fracture of the proximal end of the humerus, brachial plexus palsy, and sepsis of the shoulder joint. It should be kept in mind that multiple diagnoses can coexist (e.g., fracture with brachial plexus palsy or fracture with infection). The presence of an asymmetric Moro reflex is useful for differentiating a true paralysis (brachial plexus injury) from other causes of diminished spontaneous shoulder motion (pseudoparalysis).
Treatment
In a patient in whom upper extremity movements elicit tenderness or in those with pseudoparalysis most likely secondary to a clavicular fracture, splinting the upper extremity to the chest wall with a stockinette stretch bandage or a similar soft, expandable bandage for approximately 10 days is appropriate. Anecdotally, it may be easier and safer to clip the sleeve of the affected limb to the front of the infant’s shirt or gown to avoid the potential problems of loose and shifting bandages. Clavicular fractures in this age group heal extremely quickly without long-term sequelae. Congenital pseudarthrosis of the clavicle should not be confused with an acute fracture and usually can be differentiated easily by physical examination and radiographic appearance.
Fracture of the Clavicular Shaft in Childhood
Incidence
Fracture of the clavicle is one of the most frequent childhood fractures. The most common portion of the bone to fracture is the shaft, and such fractures account for approximately 85% of all childhood clavicular fractures.
Mechanism
The most common mechanism of a clavicular shaft fracture is a fall onto the shoulder. This mechanism accounted for 87% of the 150 prospectively studied cases carefully documented in the report by Stanley and colleagues. Usually, the bone breaks where it changes shape (concave to convex and cross-sectionally from round to flat) within the middle third of the shaft. Less commonly, the bone is fractured by a direct blow; this mechanism accounted for 7% of Stanley and colleagues’ cases. The remaining 6% of patients sustained fractures secondary to a fall on their outstretched hands.
Associated Injuries
High-energy trauma is associated with a larger number of fragments and greater fragment displacement and with a consequently higher likelihood of injury to surrounding nonosseous structures such as the brachial plexus, neighboring vessels, or apex of the lung.
Diagnosis
Characteristically, the child with an acute clavicular fracture holds the elbow of the affected limb with the opposite hand and tilts the head toward the affected side to minimize the displacing pull by the sternocleidomastoid and trapezius muscles. Radiographs are confirmatory, although for nondisplaced fractures, their results may initially be negative. The use of good soft tissue radiographic technique and careful attention to the periclavicular soft tissue shadow may detect subtle nondisplaced fractures. Overlying structures may obscure a medial physeal injury, and a Rockwood serendipity view (40° cephalad-directed tube angle) or Hobbs projection may be helpful. Children with appropriate histories and point tenderness over the clavicle but with negative primary radiographic results usually have callus at the site of injury on follow-up radiographs obtained 10 to 14 days later.
Treatment
Nonoperative
More than 200 methods of nonoperative management of a clavicular shaft fracture have been described. Most commonly, these fractures are managed with an apparatus that draws the shoulder backward (e.g., a figure-of-8 plaster wrap or a figure-of-8 bandage or strap) or a simple sling. Generally, total time of immobilization is about 3 to 4 weeks, and a gradual increase in activities is allowed as discomfort lessens. Contact sports are not recommended for approximately 6 to 8 weeks.
A common residuum of the injury is a knot or bump at the site of the fracture due to prominent healing callus. The child and parents should be made aware of this possibility at the initial visit. Characteristically, the knot or bump becomes less distinct as the bone remodels over the next 6 to 9 months. A rare finding of duplication of the clavicle due to ossification of the periosteal sleeve has been reported but was of no functional consequence. Long-term impairment as a consequence of a closed clavicular fracture managed by closed methods in childhood is rare.
Operative
Débridement followed by open reduction is indicated for the rare open clavicular shaft fracture. Internal fixation may be necessary to prevent impingement of displaced sharp bone ends on neighboring vital structures or to prevent them from protruding through the wound. A 3.5-mm or 2.7-mm reconstruction plate is appropriate internal fixation; one should avoid using smooth pins because of concern regarding migration. Delayed wound closure and support in a figure-of-8 bandage and a sling are appropriate.
Open reduction may also be indicated for significantly displaced, irreducible fractures (e.g., those that have buttonholed through the trapezius or the fascia, with tenting and potential compromise of the skin). Management of displaced clavicular fractures in adolescents without significant skin or soft tissue compromise has become more controversial, as surgeons have attempted to extend indications and results reported for adult patients to this younger population. Multiple authors have reported successful treatment of displaced fractures in adolescents. Kubiak and Slongo reported good success using intramedullary titanium elastic nails in pediatric and adolescent patients requiring internal fixation of clavicular shaft fractures. Vander Have and associates compared operative versus nonoperative treatment in adolescent patients and found a statistically significant improvement in time to radiographic union in those treated surgically. Five patients developed symptomatic malunions in the nonoperative group, but no nonunions or malunions occurred in the surgical cohort. However, current opinion continues to favor nonoperative treatment of closed pediatric clavicular fractures. A survey of the Pediatric Orthopaedic Society of North America membership presented four different case scenarios. In all situations, the majority of respondents preferred nonoperative treatment for closed fractures.
The authors have plated the clavicle in an older adolescent who had a clavicular fracture associated with multiple rib fractures and a flail chest that needed to be managed by thoracotomy and rib stabilization ( Fig. 11-5 ). In this patient, stabilization of the clavicle contributed to stabilization of the chest wall and set the scapulothoracic articulation at the correct point on the thoracic wall. This indication for clavicular osteosynthesis is seen infrequently, even at major trauma centers.
Distal Clavicular Fracture
Relevant Anatomy
Two anatomic facts greatly enhance our understanding of trauma to the distal end of the clavicle in children. The first is that the secondary ossification center at the distal end of the clavicle remains unossified until shortly before it unites with the diaphysis in the late teenage years. The second is that the thick periosteal sleeve surrounding the distal part of the clavicle and its epiphysis provides a strong attachment for the acromioclavicular and coracoclavicular ligaments. These anatomic relationships make it easier to understand why a physeal fracture in this region is much more common than dislocation of the acromioclavicular joint, similar to the pattern of injury seen at the medial end of the clavicle. When the distal end of the clavicle fractures in a child, it creates a rent in the periosteal sleeve, and with displacement, the ossified metaphysis herniates through the rent while the unossified epiphysis is retained in the sleeve. Because the epiphysis is cartilaginous and radiolucent, it gives the radiographic appearance of what would be, in an adult, an acromioclavicular joint dislocation. However, not all distal clavicular fractures involve the physis. True fractures of the clavicular metaphysis do occur but are relatively infrequent in children ( Fig. 11-6 ).
Incidence
The lateral aspect of the clavicle, including the acromioclavicular joint, accounts for 10% of fractures of the clavicle; these fractures occur with far greater frequency than do fractures at the medial end of the bone.
Mechanism of Injury
This injury is produced by a force on the apex of the shoulder—a fall or a blow. The patient is seen with pain and tenderness over the shoulder in the area of the acromioclavicular joint. If the fracture is displaced, deformity of the shoulder and tenting of the skin may be present. In the case of a displaced physeal fracture, radiographs of the shoulder may demonstrate a high-riding lateral clavicular metaphysis in relation to the neighboring acromion. Occasionally, an associated fracture of the base of the coracoid process may be present.
Classification
Distal clavicular fractures have been classified into three types by Dameron and Rockwood. Type I is a fracture without displacement, type II is a nonarticular displaced fracture, and type III is a fracture involving the acromioclavicular joint ( Fig. 11-7 ). However, it should be noted that these classifications were formulated to describe fractures occurring in adults, and for the reasons discussed previously, fractures involving the joint are a rarity in the skeletally immature patient.
Treatment
In view of the tremendous remodeling potential (i.e., the osteogenic capacity of the retained periosteal sleeve), these injuries should be managed nonoperatively. Treatment usually consists of a simple sling or Velpeau shoulder immobilization for 3 weeks, followed by gentle functional shoulder exercises. Several reports have described Y -shaped distal clavicular anatomy or distal clavicular duplication and ascribed them to developmental causes. Ogden suggested a traumatic cause, in which one limb of the Y is the original, now upwardly displaced, lateral clavicular metaphysis ( Fig. 11-8 ) and the second limb is the bone that forms in the retained (nondisplaced) periosteal sleeve. The condition is asymptomatic and does not require treatment. As a rule, one should expect a normal-appearing and normally functioning shoulder after healing of a distal clavicular fracture in a child.
Acromioclavicular Joint Injury
A true injury to the acromioclavicular joint is rare in children but may be seen in older adolescents. The mechanism of injury is the same as in adults: a blow to or a fall on the point of the shoulder. Allman classified these injuries into three types: type I, a mild sprain of the acromioclavicular ligaments without subluxation of the joint; type II, a sprain of the acromioclavicular ligaments with subluxation of the joint but no disruption of the coracoclavicular ligament; and type III, dislocation of the joint with disruption of both ligaments, which is seen on anteroposterior (AP) radiographs as an increase in the coracoclavicular distance ( Fig. 11-9 ).
Treatment of type I and II injuries consists of a simple form of immobilization such as a sling or shoulder Velpeau dressing for 3 to 4 weeks. The immobilization should be followed by functional shoulder exercises, and gradual progression of movement should be dictated by patient comfort. Type I injuries do well as a rule. Type II injuries are occasionally accompanied by late sequelae such as weakness and pain with shoulder movement. Affected individuals may be candidates for a reconstruction procedure in their early adult years, such as a Weaver–Dunn reconstruction or other acromioclavicular ligament reconstruction. Discussion in the adult literature has been abundant regarding the management of type III injuries; however, because of the rarity of the injury in children, little exists in the literature on this subject in skeletally immature patients.
Indications for open treatment include acromioclavicular joint injuries in conjunction with scapulothoracic dissociation, irreducible and widely displaced injuries in which the clavicle becomes subcutaneous and buttonholed through the fibers of the trapezius, open injuries requiring débridement and irrigation, and patient and parent preference for early stabilization and mobilization. Early operative fixation may be most appropriate in high-level throwing or lifting athletes. These uncommon indications notwithstanding, nonoperative management is the treatment of choice for essentially all types of this injury in children and adolescents.
Scapula
Developmental Anatomy
The scapula begins to ossify from a single center at the eighth week of fetal life. The ossification center for the middle of the coracoid process forms at 1 year of age and that for the base of the coracoid and upper portion of the glenoid at 10 years. At puberty, two to five centers form in the acromion and fuse by 22 years of age; failure of any of these centers to fuse gives rise to the normal variant termed os acromiale ( Fig. 11-10 ). A horseshoe-shaped secondary center at the inferior rim of the glenoid, a center for the medial border, and a center for the inferior angle form and later fuse with the remainder of the bone by 22 years of age.
Anatomy
The scapula is a flat bone richly invested in muscle over the posterosuperolateral aspect of the chest wall; there are multiple sites of muscle attachment (n = 17) on both its superficial and deep aspects, and only the dorsal edge of its spine and acromion are subcutaneous. It articulates with the clavicle at the acromioclavicular joint, with the humerus at the glenohumeral joint, and functionally with the chest wall through the scapulothoracic articulation (not a true joint). The muscles that invest the scapula participate in shoulder movements by rotating, stabilizing, and translating the scapula on the chest wall. The articular surface of the glenoid is pear-shaped; a fibrocartilaginous labrum on its rim helps center the humeral head in the glenoid during function. The bony projections (i.e., the acromion and coracoid process) are oriented at 120° to each other and to the axillary border of the scapula when viewed from the true lateral aspect of the bone (the so-called Y view of the scapula; Fig. 11-11 ).
Incidence and Classification
Fractures of the scapula are rare in children and are classified according to the portion of the bone that is fractured: the body, glenoid, acromion, or coracoid.
Body Fractures
Scapular body fractures occur as a result of direct, significant trauma. With the large amount of surrounding muscle, deformity is rarely evident. Clues on physical examination include abrasions, ecchymoses, neighboring wounds, swelling, and tenderness. True AP and lateral radiographic views are usually diagnostic, but opposite-side comparison views are sometimes necessary to detect subtle injuries in children. CT may be helpful for delineating the extent of the injury ( Fig. 11-12 ).
In general, scapular body fractures, like scapulothoracic dissociations, imply absorption of a large amount of force, and associated injuries may have also occurred to the underlying chest as well as injury to neighboring neurovascular structures (e.g., subclavian and axillary vessels and the brachial plexus). In the vast majority of instances, these fractures are managed by sling immobilization of the shoulder for 2 to 3 weeks. This can be followed by gentle mobilization (e.g., pendulum exercises) and progression over a period of several weeks to full activity in accord with patient comfort and findings on physical and radiographic examinations. Open injuries require operative irrigation and débridement and may require reduction and stabilization in cases of severe displacement.
Scapulothoracic dissociation can be diagnosed on an AP view of the chest ( Fig. 11-13 ). A search for associated injury to the brachial plexus, vascular structures, and chest wall should be conducted. Scapulothoracic dissociation has not been reported in newborns or very young children but has been reported in two older children 8 and 11 years of age. Both children underwent operative repair of the detached suspensory muscles and open restoration and operative stabilization of the scapular articulation with the clavicle.
Glenoid Fractures
Generally, fractures of the glenoid most commonly are the result of a direct force on the lateral aspect of the shoulder, and the humeral head is driven into the glenoid surface. Some fractures of the glenoid are caused by forces transmitted by a fall on a flexed elbow. Whether a posterior or an anterior rim fragment is associated with a corresponding subluxation of the humeral head is determined by the position of the arm at the time of injury. CT is especially useful in assessing the size and significance of these intraarticular fractures. If the fragment is large or if a significant amount of the joint surface is involved, the glenohumeral joint may become unstable, causing the humeral head to sublux. In cases with associated glenohumeral dislocation, significant displacement of an associated glenoid rim fragment may occur.
For minimally displaced glenoid fragments not associated with humeral head subluxation or dislocation, the recommended treatment is sling immobilization for 3 weeks, followed by gentle functional shoulder exercises. For the uncommon situation of a large fragment associated with humeral head subluxation or dislocation, operative anatomic reduction with lag screw fixation ( Fig. 11-14 ) or a small “hook” or “spring” plate and repair of associated capsular tears are indicated. Careful preoperative planning is strongly recommended, and the surgical approach is dictated by the location of the fragment to be fixed. Postoperatively, the patient’s arm is immobilized in a sling for 3 weeks, followed by gentle functional exercises. Screws or plates may be removed after 3 months, but most commonly are left in place because no unanimity of opinion exists regarding the issue of implant removal in this setting. The severity of symptoms ascribed to retained implants may warrant their removal, but the symptoms should outweigh the risks associated with additional surgery.
Acromion Fractures
Fractures of the acromion are rare but can result from a direct force on the point of the shoulder. Failure of one of the several acromial epiphyses to fuse (i.e., os acromiale; see Fig. 11-10 ) is a normal developmental variant and should not be mistaken for a fracture. Comparison radiographs of the contralateral extremity may be helpful, as may reference to an appropriate radiographic atlas of normal skeletal variants. The usual treatment consists of sling immobilization for 3 weeks, followed by early functional shoulder exercises.
Coracoid Fractures
Fracture of the coracoid process is uncommon in children. The two fracture patterns seen when the injury does occur appear to represent an avulsion by the pull of either the acromioclavicular ligaments or the conjoined tendon of the coracobrachialis and short head of the biceps brachii. The first type of fracture occurs through the physis at the base of the coracoid and the upper quarter of the glenoid, and the second type occurs through the tip of the coracoid. Coracoid fractures can accompany distal clavicular fractures, apparent acromioclavicular joint injuries, and shoulder dislocations. The injury can be demonstrated by the Stryker notch view or by an axillary lateral view when the gantry is widened to include the coracoid on the film ( Fig. 11-15 ). CT scans provide the most accurate view of a potential coracoid fracture. Treatment usually consists of sling immobilization of the shoulder for 3 weeks, followed by a functional shoulder exercise program.
Glenohumeral Joint Dislocation
Developmental Anatomy
Between 4 and 7 weeks’ gestation, the proximal upper limb bud blastema differentiates into the scapula, the humerus, and an interzone. This interzone and its surrounding mesenchyme give rise to the capsule and intraarticular structures of the glenohumeral joint. Differentiation of these structures is complete by 7 to 8 weeks after fertilization; thereafter, the joint cavity, its surrounding structures, supporting elements such as the rotator cuff muscles, and tendons increase in absolute dimensions while maintaining proportional size.
Anatomy
The glenohumeral articulation is a true synovial joint of the ball-and-socket variety. The joint comprises the shallow, pear-shaped glenoid and the spherical head of the humerus. The closely related capsule, its associated glenohumeral ligaments, and its overlying rotator cuff tendons provide a mobile and dynamic extension of the glenoid cavity that centers and stabilizes the humeral head within that cavity and enables it to pass through a greater arc of motion than any other joint in the body. However, the glenohumeral joint’s major reliance on soft tissue support makes it susceptible to injury with resultant subluxation or dislocation.
Incidence
During childhood, because of the relative strength of the surrounding soft tissue structures, the growing proximal humeral physis is mechanically the weakest link in the glenohumeral articulation. Thus traumatic force to the area is most often manifested as a proximal humeral physeal fracture. During the adolescent years, as the proximal humeral growth plate begins to close and strengthen, the incidence of glenohumeral dislocation and associated capsular injuries rises. In the series reported by Rowe and colleagues of some 500 glenohumeral dislocations seen over a 20-year period, only 8 (1.6%) occurred in children younger than 10 years, whereas 99 (19.8%) occurred in patients ages 10 through 20 years. Approximately half the injuries in the 10- to 20-year-old group (48 of 99) were recurrent dislocations. Recurrence rates ranged from 20% to 100% in children younger than 10 years and from 48% to 90% in patients between the ages of 10 and 20 years. Dislocation of the shoulder during infancy is very rare but has been reported in association with brachial plexus palsy, sepsis, and congenital deformity.
Classification
Glenohumeral dislocations may be classified according to the direction of the dislocation: anterior, posterior, or inferior (the latter two are much less common). In addition, they may be classified according to cause, as shown in Figure 11-16 .
Mechanism of Injury
Anterior glenohumeral dislocation is usually produced by a force on the outstretched hand with the shoulder in abduction, external rotation, and elevation—a position that causes anterior levering of the humeral head and secondary stretching of the anterior and inferior capsular tissues. Up to 85% of patients with an anterior dislocation demonstrate evidence of anterior and inferior capsular detachment from the glenoid neck—the so-called Bankart lesion. Posterior dislocations are relatively uncommon but may be seen in patients after epileptic seizures or spasmodic muscle contractions. The mechanism of these injuries is explained by the powerful activity of the internal rotators, which act to lever the humeral head posteriorly.
Many patients with a history of atraumatic dislocation can voluntarily sublux or dislocate their shoulders. Those who perform this atraumatic, voluntary type of dislocation are more likely to be children or adolescents than adults. In the initial report by Rowe and colleagues, 20 of 26 patients with voluntary dislocations (77%) were 16 years or younger; psychiatric factors were found to play an important role in these voluntary dislocations. Whether this ability is spontaneous or acquired after an initial minimally traumatic injury is unclear. In Rowe’s series, 11 patients could recall no specific episode of initial trauma; the remaining 15 could recall a minor injury or a fall.
Diagnosis
Traumatic dislocation causes pain and swelling about the shoulder. In contradistinction, atraumatic dislocation causes little or minimal pain or swelling. The attitude of the arm at presentation is dependent on the direction of the dislocation. With an anterior dislocation, the arm is held abducted and usually slightly externally rotated; with a posterior dislocation, it is fixed in adduction and internal rotation; and with an inferior dislocation, it is held in abduction with the forearm lying on or behind the patient’s head (the so-called luxatio erecta position).
A careful neurovascular examination should be performed in all patients with a traumatic dislocation. Injury to the axillary nerve and tears of the rotator cuff tendons are sometimes seen in association with glenohumeral dislocation and should be assessed and documented. In their series of 226 anterior dislocations, Pasila and associates reported an 11% incidence of brachial plexus injuries, 8% incidence of axillary nerve injuries, and 11% incidence of rotator cuff tears. The neighboring axillary artery and vein are also at risk of injury, usually secondary to excessively forceful attempts at reduction. Radiographic evaluation should include a “trauma series” consisting of an AP and lateral view in the plane of the scapula. Because the overlying humeral head and chest wall can obscure subtle rim fractures (as well as a fracture of the lesser humeral tuberosity), an axillary lateral view or a modified axillary lateral view should also be obtained.
Treatment
Reduction of an acute, traumatic dislocation can usually be accomplished safely by any of several classic methods. For immediate reduction of an acute dislocation (as in those witnessed and clinically apparent as dislocations and treated on an athletic field), slight abduction and derotation of the affected arm with minimal traction can be attempted as described by O’Brien and associates. The Hippocratic method consists of slow and gentle traction on the affected arm with gentle internal and external rotation to disengage the humeral head. With this technique, the physician applies countertraction by placing a stockinged foot on the patient’s chest wall ( Fig. 11-17 , A ) but not in the axilla. Alternatively, one can use a modification of this technique by placing a twisted sheet around the upper part of the patient’s chest and having an assistant pull on the sheet to provide the desired countertraction ( Fig. 11-17 , B ).
