Proximal humerus fractures occur most commonly in the elderly and their incidence is increasing steadily. Fractures of the humerus can occur proximally, in the shaft (diaphysis), or distally. The majority of both proximal and midshaft humerus fractures are nondisplaced and can be treated conservatively (nonsurgically).
Proximal fractures of the humerus will be reviewed here. Nonstress and stress fractures of the shaft of the humerus are discussed separately. (See "Midshaft humeral fractures in adults" and "Stress fractures of the humeral shaft".)
The humerus is the largest bone in the upper extremity. The proximal humerus articulates with the glenoid of the scapula to form the glenohumeral (shoulder) joint (figure 1 and figure 2 and figure 3). The muscles and tendons of the rotator cuff, the acromion, and ligamentous attachments, such as those between the coracoid process of the scapula and the acromion, both stabilize the glenohumeral articulation and provide for the shoulder’s wide range of motion. The distal humerus articulates with the radius and ulna at the elbow.
According to the Neer classification, the proximal humerus is divided into four sections: the anatomical neck, the surgical neck, the greater tuberosity, and the lesser tuberosity (figure 4) . (See 'Neer classification' below.)
- The anatomical neck consists of the widened articular surface of the humeral head.
- The surgical neck is located at the constriction distal to the humeral head and tuberosities. The surgical neck is where the articular capsule attaches and several penetrating arteries enter to provide part of the vascular supply to the humeral head.
- The greater and lesser tuberosities are the sites of attachment for the tendons of the rotator cuff muscles (figure 5). The greater tuberosity is located lateral to the humeral head on the superior aspect of the humerus. It provides the attachment for three of the rotator cuff muscles: supraspinatus, infraspinatus, and teres minor. The lesser tuberosity is located on the anterior surface of the humerus and provides the attachment for the subscapularis muscle.