With an annual incidence of

Review Article Management of Complex Elbow Dislocations: A Mechanistic Approach John D. Wyrick, MD Steven K. Dailey, MD Jacob M. Gunzenhaeuser, MD E. Christopher Casstevens, MD Abstract Complex elbow dislocations (ie, fracture-dislocations) are challenging injuries to treat and may result in significant patient morbidity. Chronic instability, posttraumatic arthrosis, and poor functional outcomes are frequent. Orthopaedic surgeons should strive to optimize elbow function through restoration of articular congruity and stability coupled with early rehabilitation. Although most of these injuries require surgical management, not all complex elbow dislocations are equivalent. Understanding elbow biomechanics and the injury mechanism provides valuable insight into the variations of pathology that may be observed. Identifying the particular fracture pattern, such as an axial loading, valgus posterolateral rotatory, or varus posteromedial rotatory injury mechanism, helps guide appropriate treatment. From the University of Cincinnati, Cincinnati, Ohio. Accompanying videos are available by accessing this article online at www.jaaos.org. Dr. Wyrick or an immediate family member serves as a paid consultant to or is an employee of Stryker. None of the following authors or any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this article: Dr. Dailey, Dr. Gunzenhaeuser, and Dr. Casstevens. J Am Acad Orthop Surg 2015;23: 297-306 http://dx.doi.org/10.5435/ JAAOS-D-14-00023 Copyright 2015 by the American Academy of Orthopaedic Surgeons. With an annual incidence of approximately 5.2 cases per 100,000 person-years, dislocations of the elbow represent the second most common dislocation of the upper extremity. Approximately 26% of elbow dislocations occur with a concomitant elbow fracture. 1,2 These complex elbow dislocations may result in significant morbidity for the patient and are associated with an increased risk of chronic instability, posttraumatic arthrosis, and poor functional outcomes compared with simple dislocations. Although complex elbow dislocations are difficult problems to address, orthopaedic surgeons should strive to optimize elbow function through restoration of articular congruity and stability. Appropriate fixation maximizes functional outcomes through increased strength and range of motion (ROM) while simultaneously minimizing pain. 3 Here, we analyze three patterns of complex elbow dislocations. Axial loading, valgus posterolateral rotatory, and varus posteromedial rotatory injury mechanisms are described with particular emphasis placed on the resultant pathology, surgical management, and functional outcomes. Initial Evaluation A thorough history and physical examination guide the treatment of complex elbow dislocations. The mechanism of injury should be obtained because it can elucidate the pathology likely to be encountered and provide insight into treatment strategy. The neurovascular structures should be thoroughly evaluated. An examination of the shoulder and distal radioulnar joint should be conducted because these structures may have been injured concomitantly. AP and lateral radiographs of the elbow joint are obtained in all cases. May 2015, Vol 23, No 5 297

Management of Complex Elbow Dislocations: A Mechanistic Approach Figure 1 Illustration demonstrating that a direct, high-energy axial loading force to the olecranon can result in a transolecranon fracturedislocation. Closed reduction of the fracturedislocation should be attempted. Sedation helps achieve muscle relaxation and minimize patient discomfort. Generally, in-line traction followed by elbow flexion reduces most dislocations. Postreduction neurovascular status should be evaluated, and postreduction radiographs should be obtained. Nonconcentric reduction or widening of the joint space may indicate trapped osteochondral fragments or significant elbow instability. Preoperative CT scans are valuable for both injury evaluation and surgical planning, especially when significant comminution is present. Axial Loading Injury Mechanism An axial loading mechanism occurs when the dorsal aspect of the proximal forearm sustains a high-energy direct blow while the elbow is flexed (Figure 1). The resultant force causes the distal humerus to impact the greater sigmoid notch of the olecranon. 4 The proximal ulna fractures as the forearm is displaced anteriorly relative to the distal humerus. 5,6 This can be conceptualized as a pilon fracture of the elbow. Comminuted fractures are most common. 6 This injury pattern has been described as a transolecranon fracture-dislocation and can be subdivided into anterior or posterior, depending on the relationship of the forearm and radial head to the distal humerus. There is no consensus on the true incidence of transolecranon fracture-dislocations because the injury is often mistaken for a Bado type I Monteggia lesion, which involves disruption of the proximal radioulnar joint. Contrastingly, the proximal radioulnar joint remains intact following transolecranon fracture-dislocations; furthermore, typically both the lateral collateral ligament (LCL) and medial collateral ligament (MCL) complexes remain attached to the distal fragment. 4-7 Initial Management Because these fracture-dislocations often result from high-energy mechanisms, open fractures, ipsilateral injuries, and concurrent skeletal trauma must be ruled out. Concomitant radial head fractures are especially common. 7 Reduction should be attempted; however, some highly comminuted fracture-dislocations are very unstable, and reduction can be difficult to maintain with only a splint. Surgical fixation is indicated for these injuries. Because of the presence of intact ligaments, repair of the osseous structures is paramount, with an emphasis toward anatomic reduction of the coronoid fragment. Anatomic restoration of the contour of the greater sigmoid notch and anterior cortex of the coronoid typically results in a stable, and ultimately functional, elbow. 7 Definitive Management Although tension band wiring has been used successfully for olecranon fractures, inconsistent results and higher failure rates have been reported following fixation of transolecranon fracture-dislocations. 5,6,8 If tension band wiring is chosen, it should be used only for a simple transverse or short oblique fracture pattern without comminution. Contrastingly, plate fixation provides excellent stability for all transolecranon fracturedislocations. The patient is positioned lateral, and a posterior incision is used. The triceps insertion is preserved. Comminuted intra-articular fragments can be secured with buried Kirschner wires (K-wires) or resorbable pins. Depending on the fracture pattern, the coronoid is reduced to either the olecranon or the distal fragment. Small mini fragment plates and screws are useful for provisional fixation. Additional medial or lateral exposure of the joint can be gained by subperiosteal elevation (ie, to repair or replace the radial head or fixation of the coronoid). When advancing these skin flaps, care must be taken to identify and preserve the ulnar ligamentous attachments of the posterior band of the LCL at the crista supinatoris and the anterior band of the MCL at the sublime tubercle. Precontoured plates can be used with the option of locking screws proximally, which are placed under the triceps through a split made in the tendon. One or two home run screws provide excellent fixation, especially when a coronoid fracture is present (Figure 2). For highly comminuted fractures, provisionally pinning the olecranon to the distal humerus with K-wires can provide some stability when reducing the ulnar shaft to the olecranon. Postoperative Protocol The operative extremity is supported in a splint for 5 to 7 days. Progressive, active ROM exercises, including flexion, extension, and forearm rotation, are begun following splint removal. A hinged elbow brace can provide protection for the 298 Journal of the American Academy of Orthopaedic Surgeons

John D. Wyrick, MD, et al Figure 2 Figure 3 Preoperative (A) and postoperative (B) lateral radiographs demonstrating a transolecranon fracture-dislocation. repair in the early stages of healing. If there is concern regarding fixation, such as in comminuted fractures or older patients, then full, unprotected motion may be delayed up to 4 weeks. Resistive exercises start at 6 to8weeks. Outcomes Excellent or good outcomes are routinely achieved following management of transolecranon fracturedislocations. 5,6,8 Poor outcomes are often attributable to hardware failure, nonunion, or inadequate postoperative mobilization. In a series of 14 transolecranon fracturedislocations described by Mouhsine et al, 5 7 patients underwent tension band wiring and 7 had plate fixation. Three patients in the tension band wiring group experienced early complications: two developed clinical instability with delayed union, and one experienced implant failure. All three required revision with reconstruction plates supplemented with bone graft. Lindenhovius et al 9 investigated long-term outcomes of surgically treated olecranon fracturedislocations. At an average of 18 years following index injury, elbow arc of motion was 124. Radiographic evidence of arthritis was observed in 70% of patients; however, the Broberg-Morrey Functional Rating Index scores were excellent in five patients, good in three, and poor in only two. Valgus Posterolateral Rotatory Injury Mechanism The most common mechanism of elbow fracture-dislocation is a valgus posterolateral rotatory load. It is the result of an axial load in conjunction with both valgus and supinating forces about the elbow (Figure 3). This most commonly occurs when falling onto an outstretched arm coupled with internal rotation of the body relative to the planted upper extremity. 10 It is classically thought that the resultant force progresses from the lateral to medial structures of the elbow. First, pathologic supination avulses the lateral ulnar collateral ligament (LUCL) from the lateral epicondyle. 11 The radial head, normally a secondary restraint to valgus stress and axial load, then fractures as it subluxates inferiorly relative to the capitellum. The posterior-inferior subluxation of the greater sigmoid notch relative to the distal humerus results in a shearing force that transmits through the tip of the coronoid process. The coronoid fractures as the ulna dislocates posteriorly relative to the humerus. Lastly, extreme Illustration demonstrating that the combination of an axial load with supinating and valgus forces can result in a terrible triad injury. posterolateral displacement may disrupt the MCL complex. 11 This injury pattern often results in elbow dislocation with concomitant radial head and coronoid fractures and is known as the terrible triad (TT) of the elbow. Recent review of video-documented elbow dislocations, however, suggests that the valgus force encountered may cause initial rupture of the MCL, which is a primary restraint to valgus stress. 12 Future studies may substantiate these findings and provide more insight into the sequence of softtissue failure encountered during these injuries. Initial Management Information on the relative degree of injury is obtained; high-energy mechanisms typically cause more structural damage than do falls from a standing height. The dislocated elbow should be reduced under conscious sedation or general anesthesia in an expeditious fashion. Delay can May 2015, Vol 23, No 5 299

Management of Complex Elbow Dislocations: A Mechanistic Approach Figure 4 Postreduction (A) and postfixation (B) lateral radiographs of the elbow demonstrating a terrible triad injury. lead to neurovascular compromise, increased risk of compartment syndrome, and increased reduction difficulty as muscle spasms progress. The elbow is typically reduced by applying traction with the elbow in extension. Once the coronoid has cleared the distal humerus, the elbow is flexed. The elbow should be ranged back into extension with the forearm in pronation to get a sense of the degree of stability (ie, at which degree of flexion the elbow subluxates). If subluxation occurs at.30 of flexion, it is unstable and requires surgical repair. The distal radioulnar joint is examined for tenderness to detect a possible Essex-Lopresti injury. The elbow is splinted at 90 with the forearm in pronation, and postreduction radiographs are examined for fractures and concentric reduction. If a coronoid fracture is present, a CT scan is typically obtained to evaluate the size of the fracture fragment. If more than a coronoid tip fracture (.10%) is present, surgical repair becomes much more likely. 13 Definitive Management It is uncommon to treat TT injuries nonsurgically. To do so, the radial head fracture must be small and minimally displaced, coupled with a small-tip fracture of the coronoid. Most importantly, the elbow must be stable during postreduction ROM. Compared with a simple dislocation in which full ROM can be allowed within a week of injury, the nonsurgical protocol for TT injuries is more conservative. 14 The elbow is immobilized in a 90 splint for 2 weeks, followed by extension-block splinting with increasing terminal extension by 30 every 2 weeks. When surgical intervention is indicated, the protocol proposed by Pugh et al 15 can be implemented: (1) fixation of the coronoid, (2) fixation or replacement of the radial head, (3) repair of the LUCL complex, and (4) possible repair of the MCL (Figure 4). If the elbow remains unstable, an external fixator is applied. The approach can be either lateral, with a supplemental medial incision when indicated, or a global posterior incision. 16 The posterior incision works well but creates large skin flaps with the potential for dead-space hematoma or wound edge necrosis, although these are uncommon complications. Laterally, the extensor digitorum communis splitting approach aiming for the equator of the radial head is used. This interval is slightly anterior to the Kocher interval and minimizes soft-tissue damage while reducing risk of iatrogenic damage to the LUCL complex. 17 In more severe injuries, the extensor origin can avulse, and the tissue planes used are those created by the injury. Most TT injuries are managed through a single lateral approach, especially when the radial head is replaced. 18 The repair proceeds from deep to superficial, with the coronoid repaired first by working through the radial head fracture or following radial head excision. Next, the radial head is repaired, and finally the LCL complex. A supplemental medial approach is used to repair the MCL if residual instability is present and/or if the coronoid was not adequately addressed from the lateral side. Coronoid Process Regan and Morrey first classified fractures of the coronoid; however, the O Driscoll classification is more clinically applicable (Figure 5). A preoperative CT scan is helpful in evaluating the extent of coronoid injury. In TT injuries, a shearing force, rather than an avulsion, produces a coronoid tip fracture, which is usually classified as O Driscoll type I injury. 19,20 Most often, fracture fragments are small and/or comminuted and are amenable to repair with the suture lasso technique. Larger fragments can be addressed with small lag screws from anterior to posterior, which may be supplemented with a mini fragment plate. Recently, however, in a review of 40 patients with TT injuries, Garrigues et al 20 found that suture lasso fixation of the coronoid was superior to both lag screws and suture anchors for providing elbow stability, while simultaneously minimizing postoperative implant failure and nonunion. These authors recommend fixing the coronoid fracture in TT injuries using a suture lasso, regardless of the fracture size. 20 If the radial head is to be replaced, one can take advantage of the exposure offered by excising the radial 300 Journal of the American Academy of Orthopaedic Surgeons

John D. Wyrick, MD, et al Figure 5 O Driscoll classification of coronoid fractures. A, Type I, fracture of the tip of the coronoid. B, Type II, fracture of the anteromedial (AM) facet. C, Type III, fracture through the base of the coronoid process.d,am facet subtype 2, fracture of the anteromedial rim and tip. E, AM facet subtype 3, fracture of the anteromedial rim and sublime tubercle. head to address the coronoid. The suture lasso technique is an excellent method of achieving fracture reduction. In this technique, a No. 2 nonabsorbable suture is passed around the coronoid fragment and through the anterior capsule. The suture is then passed through two drill holes in the ulna. An anterior cruciate ligament guide has been recommended by some to aid in this process. 21 The suture is tied over the posterior cortex of the ulna with the elbow reduced and flexed after all lateral work is completed (ie, radial head, LCL complex). Radial Head Above all, the radial head should not be excised without replacement when an elbow dislocation is present. 22 The radial head is an important secondary stabilizer to valgus stress. Cadaver studies have demonstrated radial head excision with a defect $30% of the coronoid height results in complete ulnohumeral dislocation when valgus and supinating forces are applied to a flexed elbow. 13 Partial articular fractures are fixed with small headless compression screws or with standard cortical screws by countersinking the heads below the articular surface. 23,24 Additionally, precontoured radial head and neck plates or mini fragment plates can be used. Plates are placed within the safe zone of the radial head, which refers to the 116 nonarticulating arc directly opposite the proximal radioulnar joint when the forearm is in a neutral position. 25 The safe zone can be identified via palpation of the radial styloid and Lister tubercle; it lies in the plane created between these anatomic landmarks. It is usually best to replace the radial head when it is in three or more fragments. A modular prosthesis allows for a more precise fit of the correct implant height. The prosthesis should be approximately 2 mm distal to the level of the coronoid on AP radiographs. This positioning replicates the native proximal radioulnar joint and creates a parallel medial ulnohumeral joint space, which can be compared with the uninjured elbow. 26 Of note, 18 months after surgical fixation for TT injuries, there was no significant difference in functional outcome scores, ROM, or reoperation rates between patients who underwent open reduction and internal fixation of the radial head and those who underwent radial head arthroplasty. 23,24 Lateral Collateral Ligament Complex The LCL complex is almost always avulsed from its humeral attachment and is amenable to repair. A graspingtype stitch using No. 2 nonabsorbable suture can be placed through drill holes in the distal aspect of the lateral epicondyle to aid in reconstruction of the LCL. Suture anchors placed at the avulsion site are an alternative option. 27 After reduction is verified, the elbow is flexed to 90 and pronated, and the LCL sutures are tied. If a coronoid suture has been passed, it is secured at this time, as well. Elbow stability can then be assessed using the hanging arm test, in which the humerus is supported with a stack of towels while the elbow is placed in full extension with forearm supination, which allows gravity to produce a dislocating force. Concentric reduction in this position is verified with fluoroscopy. The absence of subluxation indicates elbow stability has been restored. 18,20 If the elbow is deemed unstable, the MCL and/or May 2015, Vol 23, No 5 301

Management of Complex Elbow Dislocations: A Mechanistic Approach Figure 6 Lateral radiographs of the elbow demonstrate a complex elbow dislocation following open reduction and internal fixation (A) and application of an external fixator for residual elbow instability (B). coronoid (if not adequately repaired from the lateral side) can be addressed via a medial approach. Medial Collateral Ligament and Medial Approach The coronoid contributes more to stability in TT injuries than does the MCL. This was shown by Forthman et al, 18 who obtained good or excellent results in 17 of 22 TT injuries (77%) following coronoid fracture repair without treating the MCL. When necessary, a supplemental medial approach allows access to the coronoid and the MCL. The two predominant approaches described are the Hotchkiss over the top and the flexor carpi ulnaris splitting approaches. The Hotchkiss approach uses the interval between the flexor carpi ulnaris and the palmaris longus, which improves access to the tip of the coronoid and can be used to aid coronoid fixation when necessary. Unlike the LCL, which typically avulses from the humerus in TT injuries, the MCL can avulse from the sublime tubercle, tear intrasubstance, or avulse from the humerus. Fixation depends on the location of the tear. Sublime tubercle avulsion can be repaired with No. 2 nonabsorbable suture passed through drill holes at the sublime tubercle. Alternatively, drill holes in the distal anterior surface of the medial epicondyle can be used for humeral avulsions. External Fixator The external fixator is used in salvage situations and can yield acceptable results 28,29 (Figure 6). After all lateral and medial structures have been addressed, the elbow should again be ranged and tested for instability. Residual instability is an indication for an external fixator. The fixator need not be hinged: application of a static fixator can keep the elbow reduced long enough to allow some soft-tissue healing and, thereby, some stability. The advantage of a hinged fixator is that it allows early ROM while simultaneously maintaining reduction, although its application is technically challenging. When placed improperly, the center of rotation of the fixator will not align with that of the joint. This results in a cam effect at the joint, resulting in either compression or distraction during ROM. External fixators are most commonly used for delayed presentations or failed prior surgeries. The hinged fixator is removed approximately 6 weeks postoperatively under anesthesia. The elbow is ranged under fluoroscopy, and a gentle manipulation can be performed at this time, as well. 28,29 Postoperative Protocol In regard to posterolateral rotatory injuries, if a purely lateral repair was performed, the elbow is immobilized in a splint with the forearm in pronation. If a supplemental medial repair was used, the forearm is splinted in neutral. The splint is removed within a week and replaced with a hinged elbow brace in which terminal extension is limited to 30 for 4 weeks postoperatively. Early gentle active ROM is encouraged because muscle contraction provides stabilizing compressive forces across the joint, whereas passive motion risks distraction and subluxation. 30 Forearm rotation exercises are performed concurrently with the elbow at 90 to prevent a rotational contracture. Exercises should be performed with the shoulder adducted because significant varus stress is placed on the elbow during shoulder abduction. 27 Resistive exercises are started and progressed beginning 6 to 8 weeks postoperatively. Outcomes TT injuries are challenging to treat and historically have had poor outcomes; however, better understanding of elbow biomechanics, coupled with modern implants and surgical techniques, has allowed a systematic approach to treatment. A summary of the results from several series show a mean flexion-extension arc range of between 100 to 115, and Disabilities of the Arm, Shoulder and Hand scores range from 16 to 23. 15,20,21,31 Functional outcomes, although not outstanding, should be expected with proper management. 302 Journal of the American Academy of Orthopaedic Surgeons

John D. Wyrick, MD, et al Varus Posteromedial Rotatory Injury Mechanism Varus posteromedial rotatory loading has been described as occurring with a backward fall onto the outstretched arm, but other positions may cause this, as well 12,32 (Figure 7). The primary mechanism is a varus load that ruptures the LCL complex and causes the trochlea to fracture the anteromedial (AM) facet of the coronoid as the deformity progresses. With further internal rotation or pronation of the forearm, the coronoid dislocates posterior to the trochlea. 33 The AM facet is especially prone to injury with varus loading because 60% of the facet is unsupported by the ulnar metaphysis. The radial head typically is not fractured. 34 The O Driscoll classification system is useful for the description of coronoid fractures observed with this injury pattern. The AM facet fracture is classified as an O Driscoll type II injury. This type is further divided into three subtypes based on extension of the fracture from the central facet to involve the AM rim (subtype 1), AM rim and tip (subtype 2), or subtype 1 plus the sublime tubercle (subtype 3) (Figure 5). Increasing instability occurs with increasing subtypes. A biomechanical study by Pollock et al 35 investigated the effect of LUCL repair on varus instability following either 2.5-mm or 5-mm AM facet fractures for all O Driscoll type II subtypes. They found that 5-mm fragments of all subtypes resulted in residual instability, even following LUCL repair. With 2.5-mm fragments, severe varus and valgus instability was noted in subtypes 2 and 3 regardless of LUCL repair. 35 This study suggests that surgical fixation is necessary to restore elbow stability in the great majority of AM facet fractures. O Driscoll type III fractures, involving the coronoid base, may also be encountered. These occur with a more posteriorly directed shearing force, are very unstable, and also require surgical fixation. Initial Management One must have a high index of suspicion to accurately diagnose posteromedial rotatory instability because of its often subtle clinical presentation and innocuous radiographic appearance. AP radiographs must be carefully evaluated for a narrowed or incongruent medial joint space coupled with gapping of the radiocapitellar space. Lateral radiographs may show a double crescent sign, indicating a depressed AM facet fracture. 32 Stability should be assessed by reproducing the varus posteromedial load as the elbow is brought from flexion into extension. Subluxation or redislocation of the elbow identifies the injury pattern. Preferably, examination is performed under general anesthesia and not repeated because it could cause further damage to the joint surface. Video 1 (Pivot Shift) is a preoperative demonstration of the lateral pivot shift test under anesthesia. The forearm is supinated while the clinician simultaneously applies a valgus moment and axial compression. The elbow is then brought from full extension into flexion. The elbow is dislocated in extension and subsequently reduces when brought into flexion, which indicates the presence of posterolateral rotatory instability. Video 2 (Valgus Instability) is a preoperative demonstration of a valgus stress test under general anesthesia. A valgus moment is applied to the elbow as it is brought from extension to flexion. Subluxation of the radial head is indicative of posterolateral rotatory instability. Video 3 (Varus Instability) is a preoperative demonstration of a varus stress test under general anesthesia. Figure 7 Illustration demonstrating that the combination of an axial load with pronating and varus forces can result in an anteromedial facet coronoid fracture. A varus moment is applied to the elbow as it is brought from flexion into extension. Posteromedial subluxation of the elbow indicates a positive examination. Three-dimensional CT reconstructions are extremely helpful for preoperative planning (Figure 8). Surgical Management A fluoroscopic evaluation under general anesthesia may reveal varus instability, with a widened lateral joint space and medial joint collapse. This finding suggests that both the LUCL complex and the coronoid require surgical intervention. The incisions can again be a matter of preference, but in this injury, it is likely that both medial and lateral structures will be repaired. The AM facet fracture can be addressed through one of several exposures. Huh et al 36 found that the flexor carpi ulnaris splitting approach provides a more extensive exposure of the AM coronoid, proximal ulna, and medial ligamentous structures than does the Hotchkiss over-the-top approach. The AM facet can also be accessed through a posterior incision following the development of a medial skin flap. 34 Alternatively, AM facet fractures can be approached through the floor of the cubital tunnel following transposition of the ulnar nerve. The AM facet is May 2015, Vol 23, No 5 303

Management of Complex Elbow Dislocations: A Mechanistic Approach Figure 8 Preoperative three-dimensional CT reconstruction (A), intraoperative fluoroscopy image (B), and radiograph after open reduction and internal fixation (C) of the elbow demonstrating an anteromedial facet fracture of the coronoid. Figure 9 Intraoperative photograph demonstrates open reduction and internal fixation of anteromedial facet fracture. C = coronoid, M = medial epicondyle of the humerus. exposed by elevating the flexor carpi ulnaris from the ulna. 16 Fixation of the AM facet fragment is achieved with application of a buttress plate and screws (Figure 9). The MCL attachment to the sublime tubercle is usually intact and should be preserved. Once the coronoid is stabilized, the LUCL complex is repaired like a posterolateral rotatory injury, via nonabsorbable suture passed through drill holes. Most AM facet fractures are amenable to internal fixation; however, if the fracture fragments are prohibitively small, a suture lasso technique can be applied. Postoperative Protocol The elbow is placed in a posterior splint in 90 of flexion with the forearm in neutral rotation. Active ROM begins within 1 week postoperatively in a hinged elbow brace. Again, varus stress to the elbow should be minimized by having the patient perform therapy with the humerus adducted. These injuries can range aggressively depending on the stability of coronoid fixation. If there are concerns over the quality of bony fixation, the terminal 30 of extension can be blocked for the first 4 weeks postoperatively. Resistive strengthening exercises are initiated 6 to 8 weeks postoperatively. Outcomes Because of the recent recognition of this injury, very little data are available on outcomes following AM coronoid facet fixation. Doornberg et al 34 reviewed 18 patients at an average follow-up of 26 months. Various treatment strategies were implemented, including seven patients who were treated nonsurgically. Nine patients were thought to have inadequate treatment (seven nonsurgical, one lag screw, one plate) and had an average flexion extension arc of 99 and an average Broberg-Morrey rating of 83. Seven of these patients experienced residual instability or dislocation. The other nine patients were felt to have secure fixation (eight plate, one suture); their average ROM was 131 and average Broberg- Morrey rating, 97. The authors concluded that most patients would benefit from stable repair of their AM facet fractures. 34 Summary Complex elbow dislocations are complicated injuries that are challenging to treat; however, not all of these injuries are equivalent. Understanding elbow biomechanics and mechanism of injury provides valuable insight into the variations of pathology that may be observed. Identification of the particular fracture pattern encountered helps guide appropriate treatment. Systematic protocols to address these 304 Journal of the American Academy of Orthopaedic Surgeons

John D. Wyrick, MD, et al injuries have resulted in improved functional outcomes through the optimization of elbow stability and articular congruency. Although results are often acceptable, complex elbow dislocations still frequently result in residual elbow stiffness and arthrosis. Further investigation into methods of fixation following complex elbow dislocations should continue the trend of improved patient outcomes. Acknowledgment Special thanks to Alex Bubb, BA, for the art illustrating mechanisms of injury. References Evidence-based Medicine: Levels of evidence are described in the table of contents. In this article, reference 1 is a level II study. References 2, 7, 9, 14, 20, 23, 24, 29, and 34 are level III studies. References 3-6, 8, 12, 15, 18, 19, 21, 22, 26-28, 31, and 32 are level IV studies. References 16 and 33 are level V expert opinion. References printed in bold type are those published within the past 5 years. 1. 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Doornberg J, Ring D, Jupiter JB: Effective treatment of fracture-dislocations of the olecranon requires a stable trochlear notch. Clin Orthop Relat Res 2004;429(429): 292-300. 8. Mortazavi SM, Asadollahi S, Tahririan MA: Functional outcome following treatment of transolecranon fracture-dislocation of the elbow. Injury 2006;37(3):284-288. 9. Lindenhovius AL, Brouwer KM, Doornberg JN, Ring DC, Kloen P: Longterm outcome of operatively treated fracture-dislocations of the olecranon. J Orthop Trauma 2008;22(5):325-331. 10. Wake H, Hashizume H, Nishida K, Inoue H, Nagayama N: Biomechanical analysis of the mechanism of elbow fracture-dislocations by compression force. J Orthop Sci 2004;9(1):44-50. 11. Deutch SR, Jensen SL, Tyrdal S, Olsen BS, Sneppen O: Elbow joint stability following experimental osteoligamentous injury and reconstruction. J Shoulder Elbow Surg 2003;12(5):466-471. 12. Schreiber JJ, Warren RF, Hotchkiss RN, Daluiski A: An online video investigation into the mechanism of elbow dislocation. J Hand Surg Am 2013;38(3):488-494. 13. Schneeberger AG, Sadowski MM, Jacob HA: Coronoid process and radial head as posterolateral rotatory stabilizers of the elbow. J Bone Joint Surg Am 2004;86 (5):975-982. 14. Anakwe RE, Middleton SD, Jenkins PJ, McQueen MM, Court-Brown CM: Patientreported outcomes after simple dislocation of the elbow. J Bone Joint Surg Am 2011;93 (13):1220-1226. 15. Pugh DM, Wild LM, Schemitsch EH, King GJ, McKee MD: Standard surgical protocol to treat elbow dislocations with radial head and coronoid fractures. J Bone Joint Surg Am 2004;86(6):1122-1130. 16. Cheung EV, Steinmann SP: Surgical approaches to the elbow. J Am Acad Orthop Surg 2009;17(5):325-333. 17. Desloges W, Louati H, Papp SR, Pollock JW: Objective analysis of lateral elbow exposure with the extensor digitorum communis split compared with the Kocher interval. 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