Background
The primary function of the scapula is to attach the upper extremity to the thorax and provide a stabilized platform for upper extremity movement. The scapula is attached to the clavicle by the acromioclavicular and coracoclavicular ligaments and articulates with the humerus. The scapula is protected by its surrounding musculature (supraspinatus, infraspinatus, subscapularis) and its ability to move along the wall of the thorax; the body and spine of the scapula are most protected. Fractures to scapular structures typically require significant force. These factors explain the infrequent occurrence of scapular fractures.
Pathophysiology
The primary anatomic features of the scapula provide insight into the mechanisms of injury and offer a convenient classification system. Injuries to the body or the spine of the scapula typically result from a direct blow with significant force, as depicted in the image below, such as from a motor vehicle accident or a fall.
Scapular anatomy. Muscle origin and insertion. Scapular fractures are caused by different mechanisms. Acromion injuries usually result from a direct downward force to the shoulder. Scapular neck fractures most frequently result from an anterior or posterior force applied to the shoulder. Glenoid rim fractures most often result from force transmitted along the humerus after a fall onto a flexed elbow. Stellate glenoid fractures usually follow a direct blow to the lateral shoulder. Finally, coracoid process fractures may result from either a direct blow to the superior aspect of the shoulder or a forceful muscular contraction that causes an avulsion fracture. Classification of these fractures is depicted below.
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 Epidemiology
Frequency
United States
Scapular fractures occur infrequently and account for approximately 1% of all fractures and fewer than 5% of shoulder girdle injuries.[1]
Mortality/Morbidity
Morbidity and mortality result primarily from associated injuries.
Traditional wisdom holds that scapular fractures serve as markers of increased morbidity and mortality in patients with blunt trauma. One retrospective study comparing patients with scapular fractures due to blunt trauma with control subjects matched for age, sex, and mechanism of injury demonstrated an increase in associated thoracic injuries yet revealed no difference in mortality or neurovascular injury.[2] Another study confirmed an association between scapular fractures and concomitant injuries but noted that most of the association could be explained by differences in injury severity scores.[3]
A large force is usually required to fracture the scapula, particularly the body or the spine; however, suspect scapular fractures and thoroughly search for associated injuries.
Sex
Scapular fractures are more common among men than among women because of their increased incidence of significant blunt trauma.
Age
Scapular fractures predominate in persons aged 25-40 years because of the increased occurrence of significant blunt trauma in this population.
Zlowodzki M, Bhandari M, Zelle BA, Kregor PJ, Cole PA. Treatment of scapula fractures: systematic review of 520 fractures in 22 case series. J Orthop Trauma. Mar 2006;20(3):230-3. [Medline].
Stephens NG, Morgan AS, Corvo P, Bernstein BA. Significance of scapular fracture in the blunt-trauma patient. Ann Emerg Med. Oct 1995;26(4):439-42. [Medline].
Baldwin KD, Ohman-Strickland P, Mehta S, Hume E. Scapula fractures: a marker for concomitant injury? A retrospective review of data in the National Trauma Database. J Trauma. Aug 2008;65(2):430-5. [Medline].
McAdams TR, Blevins FT, Martin TP, DeCoster TA. The role of plain films and computed tomography in the evaluation of scapular neck fractures. J Orthop Trauma. Jan 2002;16(1):7-11. [Medline].
Bartonicek J, Tucek M, Fric V. [Radiographic evaluation of scapula fractures]. Rozhl Chir. Feb 2009;88(2):84-8. [Medline].
Hart RG, Rittenberry TJ, Uehara DT. Handbook of Orthopaedic Emergencies. Lippincott-Raven; 1999:149-55.
Rosen P, Barkin R. Emergency Medicine: Concepts and Clinical Practice. Mosby Year Book; 2002:584-586.
Simon R, Koenigcknecht S. Emergency Orthopedics: The Extremities. Appleton and Lange; 1995:207-15.
Tintinelli J, Ruiz E, Krome R. Emergency Medicine: A Comprehensive Study Guide. McGraw-Hill; 2000:1784-1787.
Veysi VT, Mittal R, Agarwal S, Dosani A, Giannoudis PV. Multiple trauma and scapula fractures: so what?. J Trauma. Dec 2003;55(6):1145-7. [Medline].
Print
