*The views expressed in this chapter are those of the author(s) and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense or the United States Government. Nicholas J. Erdle, Dominic L. Van Nielen, and Christopher S. Smith are military service members and this work was prepared as part of their official duties. Title 17 U.S.C. 105 provides that ‘Copyright protection under this title is not available for any work of the United States Government.’ Title 17 U.S.C. 101 defines a United States Government work as a work prepared by a military service member or employee of the United States Government as part of that person’s official duties.
- The humerus is a tubular-shaped long bone whose shaft is defined from the proximal border of the pectoralis major insertion to the supracondylar ridge distally.1
- Proximally, the diaphysis is uniformly cylindrical changing to a conical shape in the midshaft and then more flattened distally in the coronal plane.
- Typically, the anterior and posterior cortices represent the flatter sides of the bone for plating, but any surface is amenable to plate fixation assuming adequate protection of the neurovascular structures.
- The deltoid tuberosity is located laterally at the junction of the proximal and middle thirds of the diaphysis and represents a potential director of deforming varus forces.
- The spiral groove is a posterior bony landmark on the humerus corresponding to the path of the radial nerve and deep brachial artery. Proximally, the medial aspect of the spiral groove is approximately 10 to 14 cm distal to the acromion with the lateral edge at 14 to 21 cm. From the distal landmark of the lateral epicondyle, it can be found medially at 16 to 20 cm and laterally around 10 to 15 cm.2
- Proximally, the axillary nerve is encountered 5 to 7 cm distal to the lateral edge of the acromion.2
- Manipulation of the fractured humerus preoperatively and intraoperatively may have clinically important neurovascular implications.
Radiographic Anatomy/Preoperative Imaging
Typically, two orthogonal views are sufficient for imaging fractures of the humeral diaphysis. Fracture patterns that extend into the proximal or distal thirds may also benefit from dedicated views of the shoulder and elbow. Advanced CT imaging is rarely necessary unless pathological fracture or intra-articular extension is suspected.
Anteroposterior (AP) View
- The AP view is performed with the greater tuberosity and medial epicondyle oriented 180 degrees to each other in the coronal view such that an AP of the distal humerus serves as a reference for rotation of the unstable distal fragment.
- In cases of humeral shaft fracture, the proximal lateral view is performed with an “on face” view of the glenoid and a lateral of the distal humerus demonstrating overlap of the capitellar and trochlear cortices forming a “teardrop” (cortical overlap of the coronoid and olecranon fossae).
- In order to prevent rotation through the fracture site, a transthoracic view should be obtained with the arm held at against the chest wall. Alternatively, with adequate anesthesia, the arm can be abducted over a cassette for lateral imaging (Fig. 5-1A and B).
In patients with a fracture of the humeral shaft, additional considerations must be taken while obtaining orthogonal views to avoid rotation through the fracture site. (A) Note that rotation of the brachium to obtain a lateral of the distal humerus results in rotation through the fracture site in close proximity to the radial nerve and deep brachial artery, with the humeral head maintaining the same orientation at the glenohumeral joint. (B) With supported abduction of the extremity, both AP and lateral views of the humerus can be obtained with less theoretical risk of insult to the structures in the spiral groove.
Although important in the decision-making process, the radiographic appearance of a displaced humerus fracture is not an indication for operative treatment. With coronal angulation <30 degrees, sagittal angulation <20 degrees, and shortening <3 cm, a majority of humeral shaft fractures are amenable to conservative treatment and bony union. Relative indications for operative treatment include open fractures, associated articular fractures, neurovascular injury, “floating elbow” injuries, polytrauma, pathologic fractures, and failure of closed management to achieve alignment within the tolerances (Fig. 5-2A–C).1
Intraoperative fluoroscopic images demonstrate the utility of obtaining orthogonal views to ensure angular alignment of humeral shaft fracture. A lag screw placed in the butterfly fragment and a smaller compression plate assist in obtaining reduction and provisional stabilization prior to placement of the larger plate (Fig. 5-3A and B).