Scapula fracture is an uncommon injury. The scapula is a bone that sits congruently against the ribs and stabilizes the upper extremity against the thorax. It links the upper extremity to the axial skeleton through the glenoid, the acromioclavicular joint, clavicle, and sternoclavicular joint.
Scapula fractures are associated with high-energy trauma. Therefore, associated pulmonary or head injury may be present.
Scapula fractures contribute to less than 1% of fractures. The body of the scapula and the spine of the scapula together contribute to more than 50% of scapula fractures.
The low incidence of scapula fracture has been attributed to
- Thickened edges of the scapula
- Mobility and recoil of the bone
- great mobility with recoil, and its layers of muscle around it. Scapula fracture generally occurs in young patients.
Mechanisms of Injury of Scapula Fracture
- Indirect injury
- Load is transmitted axially through the arm on the outstretched arm
- Direct Injury
- Direct trauma from a blow or fall
- Traction Injury
- Pull by muscles or ligaments may cause avulsion fractures.
Injuries often Associated with Scapula Fractures
Scapula fractures especially the ones in high energy injury setting are associated with many other injuries, some of which could be critical. According to estimate 80-90% of scapula fractures have associated injuries
- Injury to other bones
- Rib fractures – About half the cases
- Ipsilateral clavicle – 25%
- Spine fracture- about 30%
- Brachial plexus injury
- Pulmonary injury
- Pneumothorax- In about 30%
- pulmonary contusion – in about 40%
- Head injury in a third of cases
- Vascular injury in about 10%
Relevant Anatomy of Scapula
The scapula connects trunk with upper limb. It is also called shoulder blade.
The scapula is a triangular flat bone of the shoulder girdle that articulates with the head of the humerus at the glenohumeral joint, and with the lateral end of the clavicle at the acromioclavicular joint. In doing so, it connects the upper limb to the trunk.
The scapula provides attachment for a number of muscles of the arm and shoulder.
The scapula has got two surfaces, three borders, three angles, and three processes.
Surfaces of Scapula
The scapula has got two surfaces – costal surface that abuts the thorax and dorsal surface which can be felt when we palpate the bone from behind.
The Costal surface
The costal surface of the scapula is concave and is directed medially and forwards.
The coracoid process is a hook-like projection originating from the superolateral surface of the costal scapula which lies just underneath the clavicle.
The Dorsal Surface
This surface gives attachment to the spine of the scapula which divides the surface into a smaller supraspinous fossa and a larger infraspinous fossa. The two fossae are connected by the spinoglenoid notch, situated lateral to the root of the spine.
Acromion is the projection of the spine that arches over the glenohumeral joint and articulates with the clavicle.
Borders, Angles, and Processes
The scapula has three borders, three angles and three processes.
- Superior border
- Lateral border
- Medial border
- The superior angle is covered by the trapezius.
- The inferior angle is covered by the latissimus dorsi
- The lateral angle is broad and bears the glenoid cavity
- The spinous process or spine of scapula
- The acromion process
- Coracoid process
For more details on Anatomy, visit Anatomy of Scapula
Types of Scapula Fracture
For ease of classification and discussion, scapular fractures are broadly classified based on their anatomical location.
- Coracoid fractures
- Acromion fractures
- Glenoid fractures
- Neck fractures
- Scapular body fractures
- Scapulothoracic dissociation
Coracoid and Acromion Fractures
Fracture of Acromion
- Type I are minimally displaced and can be treated nonoperatively.
- Type II fractures are displaced but do not cause a reduction in the subacromial space. Can be treated non operatively.
- Displaced type III fractures with reduction of the subacromial space. These fractures would need surgical intervention
- Proximal to coracoclavicular ligaments
- Distal to the coracoclavicular ligaments
The former type is more severe and may require surgical fixation.
Glenoid and Neck
Extraarticular Glenoid neck Fractures
These might be associated with acromioclavicular separation or clavicular fracture.
Intraarticular Glenoid Neck Fractures
They are further classified into six subtypes
- Type I – Fractures of the glenoid rim
- type IA- Anterior rim fracture
- type IB- Posterior rim fracture
- Type II – Fracture line through the glenoid fossa exiting at the lateral border of the scapula
- Type III – Fracture line through the glenoid fossa exiting at the superior border of the scapula
- Type IV – Fracture line through the glenoid fossa exiting at the medial border of the scapula
- Type IV fracture in combination with other fracture patterns
- Type V
- A – Combination of types II and IV
- B – Combination of types III and IV
- C – Combination of types II, III, and IV
- Type VI – Comminuted fracture
Presentation of Scapula Fracture
There is often a history of trauma due to a motor vehicle accident or a fall. There is a complaint of pain in the shoulder region and movements of the arm are painful. Swelling and bruises may be evident.
Associated injuries to other points in the shoulder girdle, the thoracic cage, and soft tissues are common and the patient should be evaluated for these associated injuries.
The following views are helpful for scapula fractures.
- A true anteroposterior view of the scapula
- True scapular lateral view
- The axillary lateral view
Because of their unique location and bony overlap, some scapular fractures may be difficult to visualize. X-ryas help to define the type and extent of the fracture.
The computed tomographic scan is important in evaluating glenoid or coracoid fractures.
3D CT reconstruction helps to assess the displacement of glenoid intraarticular fractures.
Treatment of Scapula Fracture
Mostly, the scapular fracture can be treated nonoperatively. Results have in general been satisfactory with conservative treatment. Nonoperative treatment generally consists of sling support for 3-4 weeks and early rehabilitation.
However few might require surgical treatment.
Operative treatment aims at the reduction and fixation of the fracture fragments.
Open reduction and internal fixation is the treatment of choice when indicated.
Operative treatment is indicated in
- Glenohumeral instability
- > 25% glenoid involvement with subluxation of humerus
- > 5mm of articular surface step off or major gap
- Excessive medialization of glenoid
- Displaced fractures of the neck of scapula
- Angulation more than 40 degrees
- Translation of more than 1 cm
- Open fracture
- Injury to rotator cuff with loss of function
- Displaced coracoid fractures [More than 1cm of displacement]
- Double disruption of the superior shoulder suspensory complex
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- Brown C, Elmobdy K, Raja AS, Rodriguez RM. Scapular Fractures in the Pan-scan Era. Acad Emerg Med. 2018 Jul. 25 (7):738-743.
- Bartonicek J, Tucek M, Fric V, Obruba P. Fractures of the scapular neck: diagnosis, classifications and treatment. Int Orthop. 2014 Oct. 38 (10):2163-73.