eMedicine Specialties > Orthopedic Surgery > Elbow

Olecranon Fractures

Author: James W Pritchett, MD, FACS, Clinical Associate Professor of Orthopedic Surgery and Sports Medicine, University of Washington School of Medicine
Coauthor(s): Margaret A Porembski, MD, Research Fellow, Department of Surgery, Massachusetts General Hospital, Shriner's Burns Hospital, Harvard Medical School
Contributor Information and Disclosures

Updated: Dec 29, 2006

Introduction

The human's unique prehensile skill largely depends on the integrity of the bones, ligaments, and muscles around the elbow joint. The elbow not only bends the arm but also permits pronation and supination of the hand. Fractures of the olecranon are common and are usually detected easily.

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History of the Procedure

See Treatment, Intraoperative details.

Problem

The olecranon is the proximal bony projection of the ulna at the elbow. Olecranon fractures are a diverse group of injuries, ranging from simple nondisplaced fractures to complex fracture dislocations of the elbow joint.

Frequency

Despite the fact that the olecranon is a very heavy, strong process of bone, it is fractured rather frequently in adults. This is due partly to its exposed position on the point of the elbow, where most direct injuries to the elbow occur, and partly to the tremendous cross strain put on the olecranon during falls on the flexed forearm. The olecranon process is rarely broken in children, because in early life, it is short, thick, and relatively much stronger than the lower end of the humerus. Usually, children sustain supracondylar fractures of the humerus instead.

Open fractures occur in 2-31% of cases. Neurologic injuries to median, radial, or ulnar nerves may occasionally occur. Ulnar neurapraxia has been reported in 2-5% of cases. Generally, symptoms resolve with conservative treatment, but late neurolysis or transposition may occasionally be required.

Etiology

The most common mechanism of an olecranon fracture is a fall on the semiflexed supinated forearm. As the hand strikes the ground, muscles are tensed to break the fall, and the powerful triceps snaps the olecranon over the lower end of the humerus, which acts as a fulcrum. The next most frequent cause of this injury is direct trauma, as in falls on, or blows to, the point of the elbow. Occasionally, the olecranon may be fractured by hyperextension injuries, such as those resulting in elbow dislocation in adults or supracondylar fractures in children. Very rarely is the olecranon broken by muscular violence, as in throwing.

Presentation

Most olecranon fractures are isolated. However, additional injuries to the same extremity are possible. Careful examination, including that of the shoulder, clavicle, humerus, wrist, hand, and forearm, is essential. Typically, the elbow incurs both soft tissue injury and joint effusion. Examine the skin, radial and ulnar pulses, and function of the ulnar, median, and posterior interosseous nerves. Carefully assess isolated injuries, as fracture of the coronoid process of the radial head and Monteggia fracture dislocations have a significant impact on elbow stability. When a supracondylar humerus fracture occurs in conjunction with an olecranon fracture, exposure of the humerus can be obtained by using the olecranon fracture site. Similarly, when an associated coronoid and/or radial head fracture exists, reduction and fixation can be achieved via a direct posterior approach through the displaced olecranon fragment.

Although olecranon fractures generally are isolated injuries, a high index of suspicion for associated injuries is warranted in the evaluation of patients with multiple trauma. Twenty percent of patients with high-energy trauma have associated injuries (eg, long bone fracture, skull fracture, splenic injury, pulmonary contusion, axillary artery rupture).

A transverse or slightly oblique break near the base of the olecranon is the usual fracture. In oblique fractures, the fracture line tends to slope down and back and emerges on the posterior border of the olecranon. In other instances, a small piece of bone is pulled off of the proximal end of the olecranon.

Indications

Fractures with significant displacement (>2 mm) or comminution may require surgical intervention.

Relevant Anatomy

The elbow is a complex hinge joint. The major stabilizers to valgus stress (ie, bending away from the body) are the medial (ulnar) collateral ligament and the radial head. The major stabilizer to varus stress (ie, toward the body) is the lateral collateral ligament complex. The coronoid process stabilizes the humerus against the distal ulna. The olecranon also prevents anterior translation of the ulna with respect to the distal humerus. The anterior surface of the ulna is covered with articular cartilage. Therefore, all fractures (except the rare tip fractures) are intra-articular fractures. The olecranon articulates with the trochlea of the humerus. The triceps inserts into the posterior third of the olecranon and proximal ulna. The periosteum of the olecranon blends with the triceps.

The ulnar nerve lies on the posterior aspect of the elbow, posterior to the medial collateral ligament. The ulnar nerve sweeps anteriorly to join the ulnar artery. The ulnar neurovascular bundle may be at risk during Kirschner wire (K-wire) fixation.

Fracture displacement is largely due to the pull of the triceps muscle, which tends to pull a separated fragment upward but is resisted by the strong fibrous covering on the olecranon (see Image 1). The blending of fibers in the lateral ligaments, the elbow capsule, and some triceps fibers that blend with the periosteum form this fibrous covering. If the fracture force does not tear this fibrous sheath, little or no tendency toward displacement exists, even in the presence of comminution.

Most olecranon fractures exhibit little or no displacement. Fragment displacement of more than 1.5 cm is uncommon, even with complete bony and soft tissue injury. Usually, wide separation of fragments indicates an old fracture with extensive tearing of the fibrous sheath in which the unopposed triceps is contracted gradually, drawing the separated fragment upward.

Contraindications

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