Complex Monteggia Fractures in the Adult Cohort: Injury and Management

Definitive Management

Older studies, including a high proportion of patients that received non-operative management, reported inconsistent and unsatisfactory outcomes in treating Monteggia fractures.^[17–19] The current treatment of choice is operative unless contraindicated by poor health. We routinely perform surgeries for complex elbow injuries, including Monteggia fractures, in the octogenarian and nonagenarian cohort with regional anesthesia and minimal sedation. The outcomes of surgical fixation are superior and more reliable than non-operative treatment.^[20–22] If a patient must be treated conservatively, then they require splint or cast immobilization for 6 to 8 weeks with frequent skin assessments. Nonunion and persistent joint dislocation are common outcomes for widely displaced fractures treated non-operatively.

For surgical management of these injuries patients are positioned supine on the operating room table with concomitant use of the Articulated Sterile Intraoperative Positioning System (McConnell Orthopaedic Manufacturing), which allows the operative arm to be draped across the chest. A lateral decubitus position with the operative arm across the chest resting on a bump is also popular. In this latter position a sterile padded Mayo stand can aid in positioning the limb in extension.

There is a wide spectrum of injury patterns that can considerably complicate surgical reconstruction. A simple pattern with a proximal ulna fracture and radial head dislocation is straightforward utilizing the posterior approach and fracture fixation using a modern contoured plate (Figure 2). The anatomic reduction of the ulna is critical since it indirectly reduces the radiocapitellar joint. If there is a concern for a tear of the lateral collateral ligament complex off the lateral epicondyle, then a large fasciocutaneous flap can be raised laterally for clinical assessment. The lateral collateral ligament complex repair can be expeditiously performed using suture anchors (2.5 to 3.0 mm or #2 nonabsorbable suture) to the lateral epicondyle or using a bone tunnel technique to the isocentric origin. Patients can initiate early motion with therapy, usually within 2 weeks.

The complexity of the Monteggia reconstruction escalates with coronoid comminution (Jupiter IIA and IID). Unlike radial head fractures, there is no reliable or accepted "back-up" reconstructive option for the coronoid. The surgeon must restore the anatomy of the coronoid to maintain sigmoid-trochlear congruency. Segmental fracture instability with deforming forces makes maintaining the reduction challenging while simultaneous applying the dorsal plate. Although not mutually exclusive, we favor additional soft tissue stripping to achieve anatomic reduction rather than settling for poor reduction at the expense of soft tissue preservation (Figure 3).

The extensor and flexor musculatures are elevated off the lateral and medial border of the ulnar crest. The reflection of the flexor/pronator muscles from the medial border of the ulna allows the exposure of the triangular coronoid fragment. The surgeon must identify and protect the ulnar nerve and the anterior bundle of the medial collateral ligament, which are the only critical structures at risk through this exposure. This approach can be implemented without the need for a separate medial or anterior incision.

While direct visualization of the coronoid is still challenging, the fracture pattern is visible, and the reduction is possible through the cortical read. Sharp reduction forceps can access the anterior coronoid fragment, which can be reduced to the posterior cortex. Occasionally, multiple large fragments have to be reduced simultaneously to restore stability. This reduction maneuvering can be quite frustrating and adds considerable operative time. Once the reduction is achieved, multiple K-wires are placed medially and laterally to maintain the reduction (Figure 3). Extra operative time and dissection is well worth the investment to achieve near anatomic alignment, and may be less destructive overall.

For coronoid fractures that are not amenable to fixation with a plate-screw construct, a suture-lasso technique can be considered.^[23] Non-absorbable suture is passed through two drill holes placed through the coronoid fragment and proximal ulna. The suture can then be tied over the proximal ulna or the posterior plate. With medial sided dissection, coronoid specific plates can be applied, although this can be challenging from the posterior approach. For large bone defects or unreconstructable coronoid fragments, various bone grafts have been used including iliac crest bone graft and radial head osteochondral graft.^[24–26] The results are considered unpredictable due to heterotopic ossification (HO) and bone resorption.^[26]

The coronoid fracture with an associated ligamentous avulsion can lead to ulnohumeral instability with injury patterns still consistent with a Monteggia fracture.^[11] In a small case series of six patients with instability, the functional outcomes were indicative of greater disability and reduced range of motion compared to patients with Monteggia fractures with stable ulnohumeral joints. Fifty percent of the unstable patients required additional procedures, including nonunion fixation of the ulna and external fixation for persistent instability.^[11] Stable fixation of comminuted coronoid fragments is challenging, but the exposure is feasible through the posterior approach. Limited salvage options exist if the fragmentation of the bone occurs.

Inadequate reduction of the coronoid fragment directly affects the achievable outcome. The triangular coronoid fragment is often "elevated" off the proximal ulna anteriorly. If the ulnohumeral joint is stable, the malreduction of the coronoid will limit elbow motion in multiple directions. In the most severe spectrum of injury, which presents with ulnohumeral instability, the coronoid fragment is critical to maintaining the reduction of the joint. Elbow subluxation, sometimes subtle, requires additional surgery to restore a congruent joint (Figure 4). Revising prior coronoid fixation is challenging. Furthermore, poor bone stock and delayed treatment often lead to fracture fragmentation and more difficult reduction. Surgeons must explore secondary options to restore ulnohumeral joint congruency in the case of inadequate coronoid fixation.

Dynamic and static external fixators, which traditionally have been a popular, but cumbersome option, can be utilized. The presence of an ulna fracture can limit the area of pin placement, and potentially lengthen the distance between the pin fixation point and the elbow joint. In our institution, we favor the use of an Internal Joint Stabilizer (Skeletal Dynamics) or trans-articular pins with 2 mm wires to maintain a more direct reduction.^[27] The internal joint stabilizer has a baseplate secured to the proximal ulna and an axis pin through the isocentric point of the distal humerus with a hinge construct. This system allows direct ulnohumeral joint stabilization and early motion.^[28] The placement of an internal joint stabilizer on top of an olecranon plate is possible with careful implant selection, but can compromise overlying soft tissue coverage.

A modern contoured ulna plate with a combination of locking and cortical screws provide a stable construct for reliable bone healing.^[9,29] While tension band constructs have been successfully utilized, we agree with Ring et al^[29] that the dorsal contoured plates provide a stiffer construct and a more reliable outcome. The implant is carefully selected to ensure that the coronoid fragment purchase can be achieved with the posterior-to-anterior screw trajectory. Many implants allow variable locking fixation proximally, thereby providing stiff articular fixation and appropriate screw trajectory to capture the coronoid.^[30] While tension band constructs and lateral plating may be feasible in selected cases, high non-union rates have been reported.^[29] Even in cases of segmental fractures and comminution, the posterior cortical read can restore the anatomic alignment with dorsal contour plates in the majority of the cases. With proximal diaphyseal or meta-diaphyseal ulna fractures, where an olecranon fixation point is not needed, we still prefer the use of an extended olecranon plate due to its well-designed anatomic contouring. The fracture can be indirectly reduced to the plate while assessing radial length via the radiocapitellar reduction and the alignment of the distal radius ulnar joint.

When considering plates for ulna fixation, surgeons must also take into account the variations of the ulnar anatomy, especially the lateral and anterior angulations of the middle and proximal thirds. Grechenig et al^[31] found a 17.5° mean varus angulation of the proximal third of the ulna in 83% of their specimens and a mean anterior deviation of 4.5° at the junction of the middle and proximal thirds in 70% of their specimens. Sandman et al^[32] determined biomechanically that the magnitude of angular malalignment at the proximal ulnar impacts the ability of the radial head to maintain a reduction. Specifically, fixing the ulna fracture in extension promotes anterior radial head subluxation and conversely, fixing the ulna fracture in flexion promotes posterior subluxation.

In rare cases when the plate-screw construct does not allow enough screw fixation of the metaphyseal comminution, a secondary plate (around 2.7 mm) can be placed medially or laterally to provide additional fixation (Figure 5). This level of comminution and complexity will likely result in stiffness and HO. The patient should be alerted about the possible need for a contracture release several months later.

In situations where restoring ulnar length and alignment does not allow for the reduction of the radial head, then entrapment of soft-tissues should be considered. The annular ligament, anterior capsule, biceps tendon, brachial fascia, radial nerve, and median nerve have all been identified as hindrances to reduction.^[33] In these situations, the radiocapitellar joint needs to be opened, via either a Kocher or Kaplan approach, and visually inspected, followed by the resection of any blocking tissue. Recently, Hamaker et al^[34] identified a series of 119 Monteggia fracture patients, in which 17 (14%) failed to reduce after fixation of the ulna fracture. In 16 out of 17 patients, the anterior portion of the annular ligament was found to be incarcerated in the radiocapitellar joint. In another series, Eglseder et al^[33] found nine patients with irreducible radial heads out of 68 patients (13%). Furthermore, more distal injuries, such as to the distal radioulnar joint have also been identified as causes of persistent dislocation.^[35]

For fracture variants with radial head fractures, treatment options include radial head ORIF, radial head arthroplasty, and radial head excision. The Mason^[12] classification of the radial head and the number of fracture fragments is commonly considered by the surgeon to determine treatment. No clear treatment consensus exists, and the choice is often deferred to the surgeon's preference. The outcomes for isolated radial head ORIF and radial head arthroplasty are favorable.^[13,14] The controversy regarding ORIF versus arthroplasty is beyond the scope of this review.

To approach the elbow, the posterior longitudinal incision is extended to raise a large fasciocutaneous flap laterally. To avoid synostosis, the authors prefer a separate lateral extensor split approach (Kaplan) for direct access to the radiocapitellar joint. By maintaining the forearm in full pronation (after ulna fixation), PIN injury can be minimized. For surgical fixation of the radial head, we prefer headless compression screws placed in a conical fashion over plates.^[36] For radial head arthroplasty, a smooth stem arthroplasty is preferred if the radial head and neck comminution are not reconstructable.

The radial head/neck fracture can extend distally down the shaft, and this fracture extension is often nondisplaced and frequently not recognized in preoperative imaging studies. In the authors' experience, a standard radial head arthroplasty with a slightly under-sized smooth stem, thereby requiring minimal broaching, can be safely placed without additional implant fixation of the shaft. Cerclage wiring and circumferential suture can also be placed, but with risks of injuring the PIN and potentially causing synostosis. Radial head arthroplasty with extended stems are available but rarely required.

The diameter of the radial head arthroplasty is generally undersized by 2 mm from the measurement of the native radial head. To avoid over-stuffing of radial head, the lateral ulnohumeral joint space should be assessed radiographically. The gapping or asymmetry of the ulnohumeral joint in the AP view indicates over-lengthening of the radial head and neck construct.^[37] The proximal edge of the radial head is positioned approximately 2 mm distal to the lateral edge of the coronoid with AP view of the proximal ulna.^[38] Assessment of over-stuffing requires critical evaluation, and the combination of the ulna fracture and joint instability can make this determination more challenging.

The authors believe that radial head management in the setting of a complex Monteggia fracture is more fraught with complications. Egol et al^[39] retrospectively reviewed 20 patients with Monteggia variants that included radial head fractures. They found that 70% of their patients developed arthritic changes, While there was no correlation between method of treatment and The Disability of the Arm, Shoulder and Hand (DASH) scores, range of motion was greater in patients that did not require operative fixation of their radial head fracture.

A complex Monteggia reconstruction is demonstrated in Figure 6. Through a posterior approach, the proximal ulna was anatomically aligned and provisionally held with multiple K-wires. A contoured dorsal plate provided secure locking fixation of the comminuted segment including posterior-to-anterior screw fixation of the coronoid fragment. In this case, the coronoid was further augmented with 25-gauge cerclage wire to prevent anterior and distal displacement. The radial head fracture was addressed through a separate extensor split approach over the extensor mass. This allowed good exposure for arthroplasty and subsequent lateral collateral ligament repair with suture anchors.

J Am Acad Orthop Surg. 2020;28(19):e839-e848. © 2020 American Academy of Orthopaedic Surgeons