Fractures of the Proximal Ulna

Fracture of the Ulna Shaft With Dislocation of the Proximal Radioulnar Joint

The injury originally described by Monteggia is a forearm fracture-dislocation: fracture of the ulnar shaft with dislocation of the proximal radioulnar joint. ^, The angulation of the fracture and displacement of the radial head is anterolateral. The key element of treatment is stable restoration of ulnar alignment with a plate and screws, which nearly always restores alignment and function of the proximal radioulnar joint. ^{, ,}

Fracture of Proximal Ulna With Posterior Subluxation of the Radiocapitellar Joint and Fracture of the Radial Head

Extraarticular fracture of the proximal ulna metaphysis distal to the coronoid, with posterior radiocapitellar subluxation and—in most cases—fracture of the radial head, is sometimes referred to as a posterior Monteggia lesion, ^, but this grouping is confusing because the radioulnar relationship is maintained. As suggested by Jupiter and colleagues, this injury pattern has more in common with posterior olecranon fracture-dislocations ( Fig. 20.4 ). Treatment consists of realignment of the ulna, plate and screw fixation, and selective repair or replacement of the fractured radial head, with occasional reattachment of lateral collateral ligament avulsion from the epicondyle.

Olecranon Fractures and Fracture-Subluxation

The Mayo classification of olecranon fractures distinguishes three factors that have a direct influence on treatment: (1) displacement, (2) fragmentation, and (3) ulnohumeral joint subluxation ( Fig. 20.5 ). Type I fractures are the uncommon nondisplaced or minimally displaced fractures that are treated nonoperatively. Type II fractures are displaced and either simple (IIA) or fragmented (IIB). Nonfragmented fractures can be treated with a screw, wires, or suture. Fragmented fractures are repaired with a plate and screws. Type III fractures are injuries with anterior, posterior, or varus subluxation of the forearm relative to the distal humerus.

Olecranon Fracture-Subluxations

On rare occasions, a simple elbow dislocation or terrible triad injury is associated with a fracture of the olecranon ( Fig. 20.6 and Case Study 20.1 ). The pattern of olecranon fracture may represent a bony alternative to rupture of the medial collateral ligament complex. Most traumatic elbow instability featuring fracture of the olecranon does not involve complete loss of apposition of the articular surfaces (true dislocation), and the ligaments are typically relatively intact. Anterior (transolecranon) olecranon fracture-subluxations are often caused by a high-energy direct blow to the forearm. ^, The proximal ulnar fracture is often fragmented; the coronoid—when fractured—is typically fractured at the base, creating one or perhaps two large fragments ( Case Study 20.2 ). The forearm translates anteriorly with respect to the distal humerus, and the proximal radioulnar relationship is maintained ( Fig. 20.7 ). ^{, ,} Associated collateral ligament injury is unusual, ^, and the elbow is typically rendered stable once the coronoid and olecranon relationships are restored and stabilized with a plate and screws.

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Apex posterior fracture-subluxations of the olecranon are typically associated with a fracture of the base of coronoid process, fracture of the radial head, and—in about 50%—avulsion of the lateral collateral ligament origin ( Fig. 20.8 ). Apex posterior injuries are often associated with osteoporosis, and the coronoid and radial head can be quite fragmented ( Case Studies 20.3, 20.4, 20.5, and 20.6 ).

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Some olecranon fracture-subluxations have varus alignment and result in a larger fracture of the coronoid than the ( Fig. 20.9 ) anteromedial facet of the coronoid process ( Case Study 20.7 ). These are typically associated with varus injuries. The radial head is nearly always intact in varus and anterior olecranon fracture-subluxations.

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Skin Incision

A midline posterior skin incision is routine. Traumatic wounds are incorporated. Some surgeons prefer that the incision not pass directly over the olecranon tip. However, a direct midline incision may cut fewer cutaneous nerves.

Tension Band Fixation

Nonfragmented, transverse olecranon fractures with no elbow subluxation can be treated with a screw, wires, or sutures oriented to convert the tensile forces associated with elbow extension into compressive forces across the fracture—an engineering principle known as the tension band ( Fig. 20.10A and Case Study 20.8 ). These fractures can also be repaired with a plate and screws ( Case Study 20.9 ). The results are comparable. The fixation doesn’t need to be particularly strong, and attention to limiting hardware prominence is helpful. Suture was long discouraged because it tends to slacken more than wires, but more recent suturing techniques may be acceptable, including use of suture anchors.

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The fracture is opened and hematoma removed to be sure that comminution and articular involvement are limited. The periosteum and muscular attachments are elevated slightly to visualize reduction of the fragment. A large tenaculum clamp can be used to maintain reduction of the olecranon. A hole drilled in the dorsal surface of the ulna can provide a good anchor point for the distal tine of the clamp.

Kirschner Wire Technique

Two parallel Kirschner wires are drilled across the fracture site. The majority of surgeons use 0.062-inch wires, but we have used 0.045-inch wires, and our experience and data show comparable results. The wires can be drilled parallel to the ulnar diaphysis or obliquely so that they pass through the anterior ulnar cortex, just distal to the coronoid process, ^, which is thought to limit the potential for wire migration. For the latter technique, after exiting the anterior cortex, the wires are retracted from 5 to 10 mm, anticipating subsequent impaction of the wires into the olecranon process proximally.

Distal to the transition from the flat proximal ulna to the apex posterior triangular shape of the diaphysis, the extensor carpi ulnaris and flexor carpi ulnaris muscles are partly elevated to allow creation of 2.0- or 2.5-mm drill holes to pass suture or wire. Many surgeons use a single 18-gauge stainless steel wire for the tension wire, but we prefer to use two 22-gauge stainless steel wires, each passed through its own drill hole distally. The smaller wires are less prominent. An alternative is a size 5 metric sternal wire of the type used in cardiac surgery, which is approximately the same gauge as a 23-gauge wire and comes swaged to a large cutting needle. This facilitates passage through bone tunnels and through the triceps tendon.