Fractures of the Shoulder

Chapter 102 Fractures of the Shoulder

Recognition of shoulder fractures is important to allow acute lameness diagnosis and treatment and to protect normal shoulder joint mobility and function. Fractures of the shoulder are often associated with concurrent thoracic trauma and may be associated with ipsilateral brachial plexus injuries or trauma to the overlying soft tissues.

ANATOMY

The shoulder is a diarthrodial joint with a shallow ball-and-socket configuration. Major support structures of the shoulder are the loosely defined medial and lateral glenohumeral ligaments and the joint capsule. Stability is also provided by a number of muscles and tendons that cross the joint to insert on the humerus, including the supraspinatus tendon, acromial and spinous heads of the deltoideus muscle, infraspinatus tendon, coracobrachialis tendon, and teres minor tendon. The biceps brachii tendon provides minimal cranial support to the normal shoulder but is commonly transposed to provide medial or lateral support after traumatic joint luxation.

The scapula is a broad, flat bone with a prominent spine and numerous muscle origins and insertions. It is loosely attached to the chest wall through the insertions of a number of muscles, including the rhomboideus, subscapularis, and trapezius. Scapular areas can be anatomically divided into the body, spine, neck, and glenoid cavity, with differing surgical approaches and treatments recommended for fractures in each area (Fig. 102-1). In immature animals, the dorsal border of the scapula serves as a physis for long bone growth. The distal scapula has no physis for long bone growth, but the supraglenoid tubercle is a secondary center of ossification in the immature dog and this apophysis is often misdiagnosed as a fracture in dogs until radiographic closure from 6 to 7 months of age.

The proximal humerus has a number of defined tubercles with important muscle insertions. The greater tubercle provides insertions for the supraspinatus tendon cranially and the infraspinatus and teres minor tendons laterally. The deltoid tuberosity is a linear protuberence on the lateral aspect of the humerus serving as the insertion for the acromial and spinous heads of the deltoid muscle. The coracobrachialis tendon inserts on the medially located coracoid process of the proximal humerus. There is a proximal humeral physis that closes functionally at approximately 8 months and radiographically at 10 months of age in the dog, and a secondary ossification center composing the greater tubercle is visible in dogs under 5 months of age.

Important soft tissue structures that may be affected by trauma or that are important during surgical approaches include the suprascapular nerve, which crosses the scapular neck from cranial to caudal beneath the acromion; the circumflex humeral vessels, which lie just distal to the teres minor muscle beneath the spinous head of the deltoideus muscle; and the cephalic vein, which lies superficially on the craniolateral aspect of the greater tubercle.

DIAGNOSIS

FRACTURES OF THE SCAPULA

Preoperative Considerations

Aug 27, 2016 | Posted by in SMALL ANIMAL | Comments Off on Fractures of the Shoulder

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