Evaluation and Management of Monteggia Fractures

The Problem

The Monteggia fracture, or fracture of the proximal third ulna with associated subluxation or dislocation of the radial head, in fact includes a wide variety of injuries to the proximal articulations between the humerus, radius, ulna, and the forearm axis of rotation. Improperly treated, these lead to severe disability related to loss of elbow and forearm range of motion. Achieving good results when treating these injuries depends on timely identification, understanding of the pathoanatomy, and appreciating the differences between the “personalities” of different injury patterns in adults and children.

Clinical Presentation

The pediatric Monteggia fracture typically affects children between the ages of 4 and 10 years of age. They present in very much the same way as other pediatric upper extremity fractures do, with pain, deformity and limited use after fall onto an outstretched arm. The most common fracture pattern involves an ulna with apex anterior deformity with a corresponding anteriorly dislocated radial head, consistent with a hyperextension mechanism.

In adults, the most common presentation involves an axial force resulting in apex posterior deformity of the ulna and a posterior dislocation of the radial head. An accompanying radial head fracture is common. It should be noted that injury patterns vary with mechanism vector and energy as well as patient bone quality. While rare in children, global elbow instability in adult Monteggia injuries is not uncommon due to concomitant disruption of ligamentous structures and fractures of the radial head, capitellum or coronoid. A thorough inventory of all injured structures will be critical in formulating an appropriate treatment plan.

The Bado classification is a commonly used scheme that describes the direction of the radial head dislocation and the apex of the ulnar deformity. Type I and II are ulnar diaphysis fractures with apex anterior and posterior, respectively. Type III is an ulnar metaphysis fracture with apex lateral. A type IV indicates a radial shaft fracture accompanies the ulna fracture. Jupiter sub-classified the type II fracture based on the pattern of the ulna fracture.

Diagnostic Workup

History and physical exam begins any assessment. In all patients, mechanism should be elicited, as this may inform the surgeon as to the involved force vectors and likely involved structures. In the pediatric patient, history of preceding injury, or pre-injury lack of full range of motion will alert the surgeon to a chronic or previously under-treated Monteggia variant, or to a history of congenital radial head dislocation.

A full neurologic, vascular and compartment exam should be performed before and after reduction. Dislocations of the radial head may stretch and injure the posterior interosseous nerve.

Any radiographic series for forearm fracture must include quality AP and lateral views of the elbow, which are necessary and usually sufficient to identify radiocapitellar incongruity. In the normal elbow, the central axis of the radius should pass through the center of the capitellum. This holds true for all projections, and whether the radial head is ossified or not. The ulna should be scrutinized for plastic deformity or “bow sign”, with apex in the direction of radial head dislocation. The posterior ulnar cortex should be straight. Injury films should be followed with post reduction X-rays to confirm concentric reduction of the ulnohumeral and radiocapitellar joints (Figure 1).

Figure 1.

Radiographs should also include the wrist, as there may be a concomitant fracture of the distal radius, which indicates higher energy and should raise suspicion for compartment syndrome, or disruption of the interosseous membrane and longitudinal forearm instability.

Associated fractures around the elbow should be characterized to determine treatment plan, as these frequently impact elbow stability. Plain X-rays are usually sufficient, but CT can be of value in preoperative planning.

The use of MRI and ultrasound is not usually indicated, though these modalities may be used when fracture of a non-ossified radial head is suspected (in a child less than 4 years of age). Intra-operative fluoroscopic arthrogram may be the more expedient choice in this scenario.

Non–Operative Management

Because Monteggia fractures all involve disruption of the radiocapitellar joint, these injuries all require some form of intervention. In adults, obtaining and maintaining ulnar fracture and radiocapitellar reduction via closed means is not usually possible. Additionally, the prolonged immobilization of the elbow required for closed treatment typically leads to unacceptable elbow stiffness.

In the pediatric population (with open physes), however, closed reduction and cast immobilization should be the treatment of choice in the vast majority of these injuries. Under appropriate sedation, the ulnar shaft is manually reduced, which in most cases will lead to reduction of the radiocapitellar joint. If this is not the case, residual deformity of the ulna is the typical culprit. Interposed annular ligament or occasionally occult radial head fracture may be responsible.

In the typical apex volar ulna deformity with anterior radius dislocation, the forearm should be placed in supination with the elbow flexed to 90 degrees. Hyperflexion of the elbow to maintain reduction should be avoided, as the swollen tissues may compromise the traversing brachial artery and lead to decreased perfusion pressure.

Vigilant weekly radiographic follow-up after reduction is required for early identification of a redislocated radial head. This indicates a need for operative correction.

Indications for Surgery

Essentially all Monteggia fractures in adults will require operative intervention. The goals that must be accomplished are restoration of the length, alignment and rotation of the ulna, reduction of the radial head (which is usually spontaneous), and identification and appropriate treatment of concomitant ligamentous and bony injuries about the elbow in order to ensure ulnohumeral stability.

In the pediatric population, operative indications include an inability to obtain and maintain reduction of the radial head through the healing process. Residual or recurrent deformity of the ulna is the most common cause of this, as it may be difficult to correct and hold via closed means. Long oblique or comminuted fractures lack stability, and loss of ulnar length leads to difficulty keeping the radial head reduced. Additionally very proximal ulnar fractures, as is often seen in the lateral Bado 3, may be very difficult to hold reduced by closed means.

Surgical Technique

Patient set–up

In adults, operative treatment is usually performed under regional blockade and general anesthesia. The patient should be positioned supine with the arm draped over a pillow on the chest. The arm can be extended to the side for fluoroscopy. Large C-arm allows easier imaging than the mini C-arm, and provides a view of a greater proportion of the forearm, which can be helpful in judging ulnar deformity. An upper arm tourniquet should be placed, and the arm should be prepped and draped as high above the elbow as possible.

The ulna should be reduced and fixed first and will typically lead to spontaneous reduction of the radius. Management of the ulna will vary based on the subtype of fracture:

Pediatric diaphyseal ulna fracture, length stable

Most of these fractures will be treatable non-operatively. For those that require operative treatment, what is typically required is fixation that allows maintenance of angular stability. A small incision is made over the olecranon tip in line with the medullary canal. A 2.5 mm drill bit is used to gain access to the medullar canal. A heavy K wire or appropriate elastic nail, just smaller than the isthmus of the ulna is then introduced through the medullary canal in an anterograde fashion to just shy of the fracture. The fracture is then reduced, and the K wire is then advanced to capture the distal fragment. In the case of a difficult reduction, particularly in the subacute situation, a small incision over the subcutaneous border of the ulna at the fracture site will allow callous removal and direct reduction. In most cases, this technique will yield a straight ulna and lead to reduction of the radial head (Figure 2, Figure 3, Figure 4).

Figure 2.

Figure 3.

Figure 4.

Pediatric length unstable ulna fractures

An approach to the subcutaneous border of the ulna between the extensor carpi ulnaris (ECU) and flexor carpi ulnaris (FCU) is made. The fracture is identified, cleaned and anatomically reduced. Great care should be made to achieve anatomic length, alignment and rotation, as residual ulnar deformity may lead to radiocapitellar instability. In children, size-appropriate 2.7 or 3.5 mm plates with four or six cortices engaged on either side of the fracture provide appropriate stability. Plate removal should be considered in the pediatric population once fracture healing is mature.

Adult anterior and lateral fractures

The ulna is approached first through a midline posterior incision extended along its subcutaneous border. The fracture is fixed with AO technique with 3.5 mm screws and six cortices on either side of the fracture. Pre-contoured olecranon plates allow for advantageous screw positioning in more proximal fracture patterns and locking technology for osteopenic bone.

Posterior fractures

These are the most common fracture types in adults, particularly the elderly. They may present as part of a pattern of global elbow instability such as the trans-olecranon elbow fracture-dislocation. Surgical goals include anatomic repair of the ulno-humeral articulation as well as the radiocapitellar joint. An extended midline posterior approach will allow access to all structures. The ulna fracture is addressed first. If there is a coronoid fragment that requires fixation, this can frequently be reduced under direct visualization through the olecranon fracture. A type 1 coronoid fracture may be captured with a #2 non-absorbable suture through the adjacent capsule. The two limbs may be passed through drill holes from the coronoid fracture bed to the dorsal side of the ulna and tied at the end of the procedure. Larger coronoid fragments may be captured with individual appropriately sized screws. A cannulated system may simplify this step. Even larger fractures, or medial coronoid fragments that would benefit from buttressing, may be reduced and plated via an FCU splitting approach. The olecranon fracture is then provisionally reduced and fixed, and length, angular alignment and radiocapitellar congruence is scrutinized fluoroscopically. Definitive fixation with an appropriate plate is then completed.

Management of the radiocapitellar joint

In the vast majority of both pediatric Monteggia variants, reduction of the ulna leads to spontaneous reduction of the radial head. Some authors suggest that open reduction of the radiocapitellar joint allows extrication of the annular ligament that is frequently entrapped despite radiographic reduction. However, the vast majority of pediatric Monteggia fractures are treated closed with good results, and radiocapitellar reduction is usually maintained along with ulnar reduction. For these reasons, it is common practice to forgo open reduction of the radial head or formally addressing the annular ligament provided radiographic alignment is perfect.

Great care should be taken to be sure that the radial head is reduced and stable after ulnar fixation. True AP and lateral fluoroscopic views should confirm an anatomic radiocapitellar line and lack of ulnar deformity. Reduction should be maintained through flexion, extension, pronation and supination. Arthrography can aid in assessing radiocapitellar congruity in cases of non-ossified radial head. 1 mL of half-strength contrast can be injected into the elbow via the lateral approach. The arc of the radial head articular surface will be well visualized and should be concentric with the capitellum.

In the setting of persistent radial head subluxation despite anatomic ulnar reduction, open reduction should be performed. An approach to the joint is made between the anconeus and the ECU. This may require a separate incision from the one used to manage the ulna, but this interval is easily reached through a midline posterior approach. Care should be taken to stay anterior to and preserve the lateral collateral ligament. The annular ligament is frequently interposed between the radial head and capitellum. Reducing it over the radial head with forceps traction or using a Freer elevator as a shoehorn may be successful, but sharp division followed by suture repair in a reduced position is often required.

Radiocapitellar pins should be avoided whenever possible. While this technique may keep this joint reduced, it may mask an underlying deformity of the ulna and lead to repeat dislocation of the radial head once the pin is removed. In the rare setting in which a radiocapitellar pin is indicated, certain precautions should be taken. As breakage is common, the pin should be stout, and protected with a long-arm cast. Additionally, placing it in an antegrade fashion through the capitellum, the joint and out the far radial neck cortex will allow for its removal in the event of breakage.

Radial head fractures

These will not uncommonly accompany posterior fracture configurations seen in adults. Since the radial head provides a degree of stability to the elbow, only very small and undisplaced fractures may be treated closed. Fracture configurations in which there are one or two fragments are generally reconstructable. An approach between the anconeus and the ECU is made, as described above. The fragments are reduced, and fixed with small countersunk or headless screws. When there is no stable fragment attached to the radial neck to build to, a precontoured plate may be used fix the head fragment to the shaft. To avoid proximal radioulnar joint (PRUJ) impingement, screw length should be carefully selected, and plates should be applied in the non-articular safe zone. This consistently corresponds to a 90-degree arc between the radial styloid and Lister’s tubercle.

Reconstruction of radial head fractures become more difficult with increasing age and osteopenia, as well as radial neck involvement and fracture comminution. The threshold for replacement instead of reconstruction should be even lower in the setting of an adult Monteggia fracture dislocation than in an isolated radial head or neck fracture because of the necessity of an intact radial column for stability through early range of motion (Figure 5, Figure 6, Figure 7).

Figure 5.

Figure 6.

Figure 7.

Pearls and Pitfalls of Technique

• Missing the pediatric Monteggia leads to poor results.

  All “isolated ulna fractures” must be scrutinized for radiocapitellar subluxation

  Careful weekly radiographic follow-up, for the first 3 weeks after reduction is important ensure maintenance of reduction throughout treatment.

• Radiographic reading

  Radiocapitellar line: radial neck line should bisect capitellar ossific nucleus.

  Ulnar bow sign: subtle bowing in the direction of the radial head dislocation. The posterior ulnar border should be straight.

• Most pediatric Monteggia fractures can be treated via closed means.

  Comminution, long oblique and very proximal ulna fractures have a higher risk of needing operative fixation.

• Residual radiocapitellar instability is almost always a result of residual ulnar deformity.

• Adult fractures often involve collateral ligament injury and radial head and coronoid fractures.

  The surgeon should be prepared to perform appropriate repairs and replacements.

• Osteoporosis must be taken into account when treating adult fractures.

  The threshold should be low for use of locking plate technology and for replacement instead of repair of radial head.

Potential Complications

Despite increased awareness, pediatric Monteggia fractures are frequently missed upon initial evaluation. They may eventually present as chronic radial head dislocations with ulna malunion and require technically difficult corrective osteotomy and annular ligament reconstruction.

Complications related to adult Monteggia fractures include those so frequently encountered in elbow trauma. Stiffness may result from prolonged immobilization. Fixation methods should allow early ROM, though loss of reduction may occur, with resultant instability, non-union or malunion.

Post–operative Rehabilitation

Children should be placed in a well-molded long-arm cast after open or closed reduction. Once clinical and radiographic healing has occurred, generally after 4-6 weeks, the cast is removed and gradual return to activities is encouraged. Formal physiotherapy is rarely needed in the pediatric population, but elbow range of motion may take several months for complete recovery. In operative cases, pins or intramedullary nails should be removed at 4 weeks once early healing is detected radiographically.

In the adult population, rehabilitation will be predicated upon elbow stability. After open reduction and internal fixation (ORIF), the patient should be placed in a long arm splint at 90 degrees with the forearm supinated. Shoulder, hand and wrist mobilization should be encouraged immediately post-operatively. Gentle active-assist elbow range of motion is typically initiated at 7-10 days postoperatively. In the setting of a radial head or coronoid fracture or collateral ligament tear repair, the patient will be fitted with a hinged elbow brace, often with an extension block. If radial head ORIF or replacement is performed, supination / pronation should be initiated based on stability of fracture ORIF but within 2-4 weeks. Caution should be used when progressing motion in the setting of suspect fracture stability due to comminution and osteoporosis.

Outcomes/Evidence in the Literature

Ring, D, Waters, P. “Operative fixation of Monteggia fractures in Children”. JBJS British. vol. 78-B. 1996. (The results of treatment of 36 pediatric Monteggia fractures. Most incomplete ulna fractures were treated closed, while most complete ulna fractures were treated by operative fixation via either IM Kwire or plate fixation. All acute fractures had excellent results. Of eight patients that presented late, two had poor results and secondary procedures. The authors advocate early recognition and low threshold for operative fixation of complete fractures.)

Wilkins, KE. “Changes in the management of monteggia fractures”. J Pediatr Orthop. vol. 22. 2002. pp. 548-554. (The authors provide an in-depth review of the topic based on recent literature. Excellent figures illustrate the article.)

Ring, D, Jupiter, J, Simpson, S. “Monteggia fractures in adults”. JBJS. vol. 80-A. 1998. (Forty-eight adults patients with Monteggia variants were followed for at least 2 years. Results were subdivided based on Bado classification. Bado 2 fractures had poorer results secondary to ulnar malunion, synostosis, and problems related to concomitant coronoid or radial head fractures. The results suggest that when stable anatomic fixation is achieved, results are better than previous reports.)

Konrad, G, Kundel, K, Kreuz, P, Oberst, M, Sudkamp, N. “Monteggia fractures in adults: long-term results and prognostic factors”. JBJS Br. vol. 89. 2007. pp. 354-360. (Forty-seven patients with Monteggia variants were followed for a mean of 8.4 years. Fracture variations were classified both by the Bado and the Jupiter sub-classification scheme for type 2 fractures. Poor outcomes were correlated with Bado type II fracture, Jupiter type IIa fracture (in which the fracture of the ulna involves the distal part of the olecranon and the coronoid process), fracture of the radial head, coronoid fracture, and complications requiring further surgery.)

Jupiter, J, Leibovic, S, Ribbans, W, Wilk, R. “The posterior Monteggia lesion”. J Orthop Trauma. vol. 5. 1991. pp. 395-402. (The authors describe the outcomes of their series of posterior Monteggia fractures. They subdivide the Bado 2 classification into a scheme based on a “compression resistant” anterior cortex, and presence of coronoid fracture.)

McKee, M, Pugh, D, Wild, L, Schemitsch, E, King, G. “Standard surgical protocol to treat elbow dislocations with radial head and coronoid fractures. Surgical technique”. J Bone Joint Surg Am. vol. 87. 2005. pp. 22-32. (A detailed and well-illustrated description of the author’s surgical protocol which included fixation or replacement of the radial head, fixation of the coronoid fracture if possible, repair of associated capsular and lateral ligamentous injuries, and in selected cases repair of the medial collateral ligament and/or hinged external fixation.)

Summary

The Monteggia fracture involves a fracture of the ulna with an associated disruption of the radiocapitellar joint. However, there is a wide range of potentially associated pathology that must be identified, treated, and recognized that has prognostic implications. In children, most of these injuries can have excellent outcomes, provided there is accurate and timely diagnosis, and that radiocapitellar reduction is maintained. Ulnar deformity must be corrected. In adults, treatment and outcomes depend on concomitant injury to stabilizing structures of the elbow. Operative fixation must address ulnar length, alignment and rotation and provide adequate stability for early range of motion. The ulnohumeral, radiocapitellar, proximal radio-ulnar articulations must all be restored, along with supporting ligamentous structures. Treating these difficult injuries requires knowledge of the treatment algorithms, surgical techniques and implants, and appropriate post-operative rehabilitation to treat these individual components in order to achieve the best results.

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