Introduction
Traumatic injuries of the scapula have received little attention in the literature because they are uncommon. Scapula fractures account for approximately 1% of all fractures. Most scapula fractures can be managed effectively with closed treatment. Some injuries with significant displacement have poor long-term outcomes for the shoulder and the upper extremity as a whole if treated with closed techniques. This article reviews closed management of scapula fractures, discusses open treatment, and provides guidelines for injuries that require operative intervention.
Fixation of acromion fractures. (A) tension band construct; and (B) plate-screw fixation (most appropriate for proximal fractures).
Illustrations showing techniques for managing coracoid fractures. (A) interfragmentary screw fixation (if the fragment is sufficiently large and noncomminuted), and (B) excision of the distal fragment (if small and/or comminuted) and suture fixation of the conjoined tendon to the remaining coracoid process.
History of the Procedure
Historically, scapula fractures have been treated by closed means. One of the earliest descriptions of treating scapula fractures was published in 1805 in Desault's treatise on fractures.
Hardegger et al reported that if significant displacement occurs, conservative treatment alone cannot restore congruence, and stiffness and pain may result, thereby indicating open reduction and stabilization.1
Problem
As previously mentioned, scapula fractures are relatively uncommon. However, they do have a high association with other injuries.2,3 Research shows that 80-95% of scapula fractures have associated injuries. The associated injuries may be multiple and/or life-threatening. As a result, diagnosis and treatment of scapular injuries may be delayed or suboptimal. Long-term functional impairment may occur. As more focus is placed on the proper management of scapular injuries, functional outcomes should improve.
Associated injury patterns commonly involve the ipsilateral upper extremity and thorax.
- Frequencies of associated injuries are as follows:
- Rib fractures - 25-45%
- Pulmonary injury (eg, hemopneumothorax, pulmonary contusion) - 15-55%
- Humeral fractures - 12% (5-10% sustain a brachial plexus injury)
- Skull fractures - 25%
- Central neurologic deficits 5%
- Major vascular injury - 11%
- Splenic injury requiring splenectomy - 8%
Related eMedicine topics:
Proximal Humerus Fractures
Brachial Plexus Injuries, Traumatic
Skull Fracture
Closed Head Trauma
Frequency
Scapula fractures account for 1% of all fractures, 3% of shoulder girdle injuries, and 5% of all shoulder fractures. Approximately 50% of scapula fractures involve the body and spine. Fractures of the glenoid neck constitute about 25% of all scapula fractures, whereas fractures of the glenoid cavity (glenoid rim and fossa) make up approximately 10% of scapula fractures. The acromial and coracoid processes account for 8% and 7%, respectively.
Etiology
Typically, scapula fractures result from high-energy trauma. Direct forces are most common, but indirect mechanisms can also be responsible. An example of an indirect force is a fall on an outstretched arm that causes the humeral head to impact on the glenoid cavity.
Presentation
Most patients with scapula fractures present after high-energy trauma. Associated injuries are common and may delay the diagnosis. Typically, physical examination reveals swelling, tenderness, crepitus, and ecchymosis over the scapular region. Perform a careful neurovascular examination to rule out arterial injury or brachial plexopathy.
Indications
While most scapula fractures can be managed with closed treatment, consider surgical management for significantly displaced fractures.4,5 The following injuries occur with enough frequency to merit discussion of operative treatment:
- Significantly displaced fractures of the glenoid cavity (glenoid rim and fossa)
- Significantly displaced fractures of the glenoid neck
- Double disruptions of the superior shoulder suspensory complex (SSSC) in which 1 or more elements of the scapula are significantly displaced
Approximately 50% of scapula fractures involve the scapular body and spine. Avulsion fractures caused by indirect forces and injuries caused by direct trauma have been described. The latter may be severely comminuted and displaced. Despite sporadic reports describing operative management, there seems to be little enthusiasm for surgical treatment. The 2 reasons for this reluctance are that (1) there is little substantial bone stock for internal fixation, aside from the scapular spine and lateral scapular border; and (2) these fractures seem to heal reliably with a good functional result without surgical treatment. If painful scapulothoracic impingement occurs at a later date, bone prominences over the ventral scapular surface can be removed surgically.
Significantly displaced fractures of the glenoid cavity (rim and fossa)
Less than 10% of glenoid cavity fractures are significantly displaced. Ideberg reviewed over 300 such injuries and proposed the first detailed classification scheme.6 This classification subsequently was expanded by Goss (see Image below and Image 1 in Multimedia).7 Type I injuries involve the glenoid rim (IA = anterior rim, IB = posterior rim). Types II-V include fractures of the glenoid fossa. Type VI fractures include all comminuted injuries (ie, more than 2 glenoid cavity fragments).
(Click Image to enlarge.) Classification of glenoid cavity fractures: IA - Anterior rim fracture; IB - Posterior rim fracture; II - Fracture line through the glenoid fossa exiting at the lateral border of the scapula; III - Fracture line through the glenoid fossa exiting at the superior border of the scapula; IV - Fracture line through the glenoid fossa exiting at the medial border of the scapula; VA - Combination of types II and IV; VB - Combination of types III and IV; VC - Combination of types II, III, and IV; VI - Comminuted fracture
Fractures of the glenoid rim occur when the humeral head is driven against the glenoid margin. Surgical management is indicated if the fracture results in persistent subluxation of the humeral head, defined as failure of the humeral head to lie concentrically within the glenoid fossa, or if the reduction is unstable. DePalma has stated that instability can be anticipated if the fracture is displaced 10 mm or more and if at least one fourth of the anterior aspect of the glenoid cavity or one third of the posterior aspect of the glenoid cavity is involved.8
Fractures of the glenoid fossa occur when a laterally applied force drives the humeral head directly into the glenoid cavity. Soslowsky et al found the maximum depth of glenoid articular cartilage to measure 5 mm.9 Consequently, with displacement more than 5 mm, subchondral bone is exposed, making posttraumatic arthritis more likely. Kavanagh et al reported on open reduction and internal fixation (ORIF) of glenoid fossa fractures in which displacement ranged from 4 to 8 mm.10 They found ORIF to be a useful and safe technique for the treatment of selected displaced fractures of the glenoid fossa. Based on these and other studies, it seems reasonable to conclude that an articular step-off of 5 mm should warrant consideration for ORIF, and a 10-mm step-off is a definite indication for surgery.
Other indications for surgical management include (1) glenoid fossa fractures that result in significant displacement of the humeral head such that it fails to lie in the center of the glenoid cavity, thereby resulting in glenohumeral instability; and (2) fractures of the glenoid fossa with such severe separation of the fracture fragments that nonunion is likely to occur.
Glenoid neck fractures
Glenoid neck fractures that cause significant translational or angulatory displacement of the glenoid fragment can interfere with normal shoulder mechanics and/or cause glenohumeral instability. Nordqvist and Petersson evaluated 37 glenoid neck fractures treated nonoperatively and found the functional results at 10- to 20-year follow-up to be fair or poor in 32% of cases.11 Hardegger et al noted that displaced glenoid neck fractures result in a functional imbalance because the relationship of the glenohumeral joint with the acromion and nearby muscle origins is altered.1
Classification of glenoid neck fractures. Type I includes all minimally displaced fractures. Type II includes all significantly displaced fractures (translational displacement greater than or equal to 1 cm; angulatory displacement greater than or equal to 40°)
Overall, there is literature to suggest that surgery should be considered for fractures with translational displacement greater than or equal to 1 cm and/or angulatory displacement greater than or equal to 40° in either the transverse or coronal plane (see Image above and Image 2 in Multimedia).
Double disruptions of the SSSC
The SSSC is a bone/soft-tissue ring at the end of a superior and inferior bony strut (see Image below and Image 3 in Multimedia). The ring consists of the glenoid process, coracoid process, coracoclavicular ligaments, distal clavicle, acromioclavicular (AC) joint, and acromial process. The superior strut is the middle third of the clavicle. The inferior strut is the lateral scapular body and spine.
Superior shoulder suspensory complex. (A) anteroposterior view of the bony/soft tissue ring and the superior and inferior bony struts; and (B) lateral view of the bony/soft tissue ring.
Traumatic disruptions of 1 of the components of the SSSC are common. If the force is sufficient, the ring may fail in 2 or more places (double disruption), a situation in which significant displacement at 1 or both of the individual sites and of the SSSC as a whole frequently occurs. Similarly, a disruption of 1 portion of the ring, combined with a fracture of 1 of the struts or fractures of both struts, also creates a potentially unstable anatomic situation. Adverse consequences include delayed union, malunion, and nonunion. Subacromial impingement, decreased strength and muscle fatigue, discomfort due to altered shoulder mechanics, neurovascular compromise due to a drooping shoulder, and glenohumeral degenerative joint disease also can occur. If unacceptable displacement is present, surgical reduction and stabilization at the injury sites is necessary. Frequently, operative management of 1 of the injury sites satisfactorily reduces and stabilizes the second disruption indirectly.12
Herscovici et al reported results in 9 patients with ipsilateral clavicular and glenoid neck fractures.13 Seven patients were treated surgically with plate fixation of the clavicular fracture and achieved excellent results. Two patients were treated without surgery and were found to have decreased range of motion (ROM), as well as drooping of the involved shoulder. The authors strongly recommended ORIF of the clavicle to prevent glenoid neck malunion.
Combined fractures of the distal clavicle and superior aspect of the glenoid cavity is another potentially unstable situation. Each disruption may lead to displacement at the other fracture site. If displacement of the clavicular fracture site is unacceptable, surgical reduction and stabilization is indicated, usually with a Kirschner-wire (K-wire) tension-band fixation construct. Because the proximal clavicular segment is attached to the superior glenoid-coracoid process fragment by means of the coracoclavicular ligaments, this may indirectly reduce and stabilize the glenoid cavity fracture satisfactorily. If not, the glenoid fracture may also require surgical management using the surgical techniques described.
Fixation of acromion fractures. (A) tension band construct; and (B) plate-screw fixation (most appropriate for proximal fractures).
Fracture of the coracoid or acromion process with a second disruption of the SSSC is another potentially unstable situation. If displacement at either or both sites is unacceptable, surgical management is indicated. For double disruptions consisting of both an acromion and a coracoid fracture, ORIF of the acromion may be all that is required (see Image above and Image 4 in Multimedia).
Relevant Anatomy
The scapula serves as the attachment site for 18 muscles, linking it to the thorax, spine, and upper extremity. The subscapularis muscle covers the anterior surface, and the serratus anterior muscle attaches to the inferior angle along the anterior medial border. The supraspinatus and infraspinatus muscles lie on the posterior border of the scapula. Overlying them is the trapezius, which inserts on the spine and the clavicle. The deltoid originates from the scapular spine, acromion, and anterior clavicle. Many other muscles attach to the scapular margins (see Image 5).
(Click Image to enlarge.) Scapular anatomy. Muscle origin and insertion.
The coracoid process projects from the superior border of the scapula. The coracobrachialis and short head of the biceps muscles originate from the coracoid, and the pectoralis minor inserts on the coracoid. The brachial plexus and axillary artery run posterior to the pectoralis minor tendon. The scapular notch lies just medial to the coracoid base and is covered by the transverse scapular ligament. The suprascapular nerve runs under the ligament, and the suprascapular artery passes over it.
The acromion is the lateral projection from the spine of the scapula. The spinoglenoid notch is the gap between the acromion and the glenoid neck of the scapula. The suprascapular nerve and vessels pass through the notch en route to the infraspinatus.
Contraindications
Because scapula fractures often are associated with other, sometimes life-threatening injuries, delay surgery until the patient is medically stabilized. Absolute contraindications for surgery are few. In the case of a major vascular injury, such as an axillary or brachial artery tear, repair the vessel first, then follow with fracture fixation.
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References
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Further Reading
Keywords
scapula fracture, glenoid fracture, acromion fracture, coracoid fracture, scapulothoracic dissociation, double disruption of the superior shoulder suspensory complex
