Fractures in Brief: Olecranon Fractures

Introduction Olecranon fractures are relatively common injuries, accounting for approximately 10% of upper extremity fractures in adults [26]. These fractures may result from a direct blow to the proximal ulna, or indirectly, via the forceful contraction of the triceps against resistance (typically, during a fall onto an outstretched hand). Less commonly, the olecranon may fracture when the elbow is hyperextended, as the bone is impacted against the olecranon fossa of the distal humerus. For unstable injuries, operative fixation typically is required. Even after recovery, loss of ROM is not uncommon. This article provides an overview of olecranon fractures in adults; therefore, discussion of olecranon fractures in skeletally immature patients is beyond the scope of this article. Structure and Function The olecranon is the region of the proximal ulna that extends from the tip of the ulna to the coronoid process. Three main anatomic features must be recalled when treating fractures of the olecranon. First, the olecranon is the site of insertion of the triceps—a muscle whose action would tend to displace a fracture. Second, the trochlear notch of the olecranon forms a cavity in which the distal humerus sits [14], and thus all olecranon fractures, by definition, are intraarticular injuries. Third, the posterior process of the olecranon prevents posterior translation of the humerus (just as the coronoid process prevents anterior translation) and thus displacement can lead to elbow instability. Injury Considerations Olecranon fractures typically are seen in young individuals after high-energy trauma or in the elderly after low-energy falls. Although olecranon fractures most commonly occur as isolated injuries, it is essential to evaluate all patients for other injuries. Specifically, injuries to the ipsilateral extremity must be identified, including elbow fracture-dislocations, as these injuries may alter the treatment plan and result in higher rates of fracture nonunion, pain, and elbow stiffness. Diagnosis and Classification The typical presentation for a patient with an olecranon fracture is with elbow pain and swelling and inability to extend the elbow against gravity. Diagnosis of any upper extremity injury begins with a thorough physical examination of the entire extremity, including observation, palpation, and complete neurovascular examination. A palpable defect can be appreciated if there is substantial displacement of the fracture. It is extremely important to closely examine the skin for any openings given the subcutaneous location of the ulna. Isolated olecranon fractures can be identified appropriately with standard AP and lateral radiographs of the elbow. It is essential to obtain a true lateral radiograph of the elbow to evaluate the extent of the fracture, degree of displacement and comminution, and the degree of articular surface involvement. Radiographs should be examined carefully for evidence of coronoid process fracture, dislocation of the elbow, and radial head injury. More advanced imaging rarely is indicated for isolated olecranon fractures. Several classification systems have been described [4, 28] but neither has been universally accepted. Each classification system is subject to interrater variability, and none has been proven to be more reliable than the other. The challenges of testing the reliability of classification systems have been discussed in the literature [2], and this is reflected in the presence of several classification systems still in use for olecranon fractures as each serves a different purpose. The Mayo classification [4], based on displacement and ulnohumeral joint stability, is our preferred choice as it can be used to guide treatment: Type I, nondisplaced fractures, treated nonoperatively; Type II, displaced, stable fractures that require operative fixation; and Type III, displaced, unstable fractures that require operative fixation. The Schatzker classification [28] subdivides fractures based on their pattern into transverse, transverse-impacted, oblique, comminuted with associated injuries, oblique-distal, and fracture-dislocation. The AO classification [18] of proximal radius and ulna fractures tends to be used more frequently for research purposes. Briefly, Type A fractures are extraarticular metaphyseal fractures, Type B are intraarticular fractures of either the proximal radius or ulna, and Type C are intraarticular fractures of the radial head and olecranon. Treatment The goals of treating olecranon fractures are anatomic restoration of the articular surface, repair of the elbow extensor mechanism, restoration of joint stability and motion, and prevention of stiffness and other complications. Treatment options include immobilization, surgical reduction and fixation with tension-band wiring or plate osteosynthesis, and excision of the proximal fragment with triceps advancement. Nonoperative treatment rarely is indicated, but may be considered for patients with a nondisplaced fracture that does not displace at 90° elbow flexion and has an intact extensor mechanism or for partial avulsions of the triceps insertion with an intact extensor mechanism. It also may be considered for poorly functioning older adults who would not tolerate surgery. Treatment involves immobilization of the elbow in a posterior splint, orthosis, or long-arm cast in approximately 90° flexion for approximately 3 weeks, followed by progressive active elbow ROM and strengthening [24]. Operative fixation should be performed when there is articular incongruity or disruption of the extensor mechanism. Tension-band wiring [20, 32] usually provides stable fixation with a high union rate for simple noncomminuted transverse olecranon fractures [8, 33]. A tension-band construct converts the tensile distraction force of the triceps into a compressive force at the articular surface [17]. This technique involves the insertion of two parallel K wires or an intramedullary cancellous screw from the tip of the olecranon aiming distally across the fracture site, with placement of a metal wire (or heavy suture) in a figure-of-eight pattern (Fig. 1). The K wires typically are inserted in one of two configurations: (1) directed slightly anterior to engage the anterior cortex of the distal fragment of the ulna (transcortical); or (2) parallel to the long axis of the ulna (intramedullary). A recent clinical study showed significantly greater K wire instability in patients treated with intramedullary K wire placement compared with the transcortical position (78% versus 36%, respectively) and a tendency toward more osteoarthritis in patients with K wire instability [30]. Similarly, a biomechanical study showed that transcortical K wire placement has greater pullout strength and therefore less potential for K wire migration compared with intraosseous placement [19]. The use of a single intramedullary cancellous screw is an alternative to K wires for a tension-band construct or use without a tension band [21]. Patients treated with a 6.5-mm cancellous screw with or without tension banding showed clinical healing at an average of 9 weeks postoperatively and radiographic healing at an average of 13 weeks [12]. A cadaveric study showed tension-band fixation with a cancellous screw provides better fixation than tension-band fixation with K wires or cancellous screw fixation without a tension band for transverse olecranon fractures [10]. Although tension-band fixation reportedly is associated with high rates of union in simple transverse olecranon fractures, we rarely perform tension-band wiring and instead prefer plate fixation.Fig. 1A-D: (A) An AP radiograph shows a transverse noncomminuted displaced olecranon fracture. (B) A lateral radiograph shows the displacement at the articular surface. (C) An AP radiograph shows open reduction and internal fixation using tension-band wiring technique. (D) A lateral radiograph obtained after tension-band wiring shows anatomic reduction of the articular surface.Plate fixation is the best treatment for olecranon fractures that are not amenable to tension-band fixation, specifically comminuted fractures, oblique fractures distal to the midpoint of the trochlear notch, fractures involving the coronoid process, and fractures associated with fracture-dislocations of the elbow. Plate fixation of olecranon fractures provides stable fixation, high union rates, and low rates of elbow stiffness or weakness significant enough to impair daily activities [3, 5, 6, 29]. Specifically, after plate fixation for displaced olecranon fractures, patients reportedly have no difference in elbow strength or ROM except for some loss of supination, high patient satisfaction, low pain rating, and mean DASH score consistent with almost normal upper extremity function [3]. One long-term followup study showed one nonunion, arm function comparable to that of the uninjured arm in 84% of patients, triceps weakness in 7%, and continued pain in 4% [13]. Karlsson et al. also reported loss of elbow flexion and extension compared with the uninjured arm; however, loss of flexion was less than 20° in all but one patient and loss of extension was less than 20° for all but three patients. Some surgeons may elect to perform plate fixation for the majority of olecranon fractures as this provides more stable fixation (especially in rotation), reserving tension-band wiring for simple, transverse, noncomminuted fractures [27]. Plates typically are placed on the dorsal surface of the proximal ulna (Fig. 2). Several different types of plates can be used, including one-third tubular, limited contact dynamic compression, and hook and precontoured locking plates. Specific plate preference and fixation are dictated by the fracture pattern, bone quality, and surgeon preference. Anatomic restoration of the articular surface and stable fixation of olecranon fractures are required to allow early elbow ROM to prevent stiffness and maximize the patient's use of the injured extremity.Fig. 2A-E: (A) An AP radiograph shows a comminuted displaced olecranon fracture. (B) A lateral radiograph shows the articular comminution and displacement of the olecranon fracture. (C) An AP view obtained after open reduction and internal fixation shows plate and screw fixation of the fracture. (D) A lateral radiograph obtained after plate fixation shows anatomic reduction of the articular surface. (E) A radiocapitellar radiograph after plate fixation shows the articular reduction and confirms that the screws are not entering the joint.Excision of the proximal bony fragment and triceps advancement [11] rarely are used in primary treatment of olecranon fractures. The maximum amount of olecranon that can be resected is controversial and has been reported to range from 50% to 80% [15]; however, a biomechanical study suggested that as much as 50% of the articular surface can be excised without compromising elbow stability provided that the coronoid and distal trochlea are intact [1]. Beyond that amount elbow constraint may be compromised, resulting in instability. Typically, excision and triceps advancement are reserved for patients who are elderly and with low demands, patients in whom internal fixation has an unacceptably high risk of failure owing to significant comminution, or as a salvage procedure after failure of internal fixation [24]. Finally, intramedullary nails have been developed and used for the treatment of olecranon fractures with the goals of decreasing rates of symptomatic hardware and preserving vascularity while providing compression at the fracture site [7, 16, 22]. Biomechanical testing comparing intramedullary nail fixation with tension-band wiring of transverse noncomminuted olecranon fractures showed that intramedullary nail fixation was significantly stiffer with greater maximum load to failure compared with tension-band wiring [16]. Future directions include continued development of lower profile and contoured plates and further evaluation and use of intramedullary nails. Outcomes Olecranon fractures heal well in most instances. Function depends on fracture severity, length of immobilization, and host factors. Most patients can expect to have a high chance of healing with approximately 1% chance of nonunion [23], low pain rating [3, 13], and some loss of elbow ROM, most commonly loss of terminal extension [31]. The main complication after surgical treatment of olecranon fractures is symptomatic hardware, with tension-band wiring having a greater incidence than plate fixation [9, 33]. Painful hardware can be removed after fracture healing is complete. Tension-band wiring has a greater reoperation rate owing to the frequent need for hardware removal attributable to subcutaneous placement of K wires and a greater resultant risk of pain, skin breakdown, and infection [25]. Loss of terminal extension frequently is seen, and patients should be advised of this, but it rarely is clinically important with isolated olecranon fractures. Nonunion of olecranon fractures is rare [23]. Additional complications include hardware failure, infection, ulnar neuritis, heterotopic bone formation, and elbow stiffness. Five Pearls A true lateral radiograph of the elbow is the most important imaging study for identification of the extent of articular displacement, comminution, and fracture pattern. Olecranon fractures are, by their nature, intraarticular injuries (which should be reduced anatomically) and require restoration of congruency for proper joint function. Tension-band wiring results in a high rate of fracture union and low rate of triceps weakness and elbow stiffness for simple noncomminuted transverse fracture patterns but often requires hardware removal; plate fixation should be considered for comminuted fractures and injury patterns where greater rotational stability is desired. A patient with an olecranon fracture may seem to be able to actively extend the elbow, by using gravity for this action. Always check extension against gravity or mild resistance. There are soft tissue retinacula on either side of the olecranon, therefore with some nondisplaced fractures the extensor mechanism may be intact and conducive to nonoperative treatment.