Posterior malleolus fractures occur in 7% to 44% of all ankle fractures. These fractures are frequently associated with lateral and medial malleolus fractures but can less commonly occur in isolation.1 They most often occur in female adults via a low energy, twisting injury.2 Ankle fractures with a posterior malleolus component are complex injuries to manage. They carry a poor prognosis and can lead to long-term disability due to posttraumatic arthritis and instability.
Due to the heterogeneous morphology of these fractures and lack of high-quality evidence, methods of operative fixation are controversial and highly variable. Reduction of the fibula can facilitate indirect reduction of the posterior malleolus by ligamentotaxis acting through the posterior inferior tibiofibular ligament (PITFL). Most surgeons recommend fixation of the posterior malleolus when the size of the fracture is greater than 25% to 30% of the articular surface.1 However, this number is based on radiographs, which have been shown to be less accurate than computed tomography (CT) scans when evaluating these fractures.3
One of the common operative methods for fixating posterior malleolus fractures is indirect reduction via fibular fixation with percutaneous screws going from anterior to posterior. Another operative method commonly described is direct reduction and visualization through a posterolateral approach. Direct visualization and reduction of the fracture leads to a more anatomic restoration of the articular surface of the tibial plafond.4
For large posterior malleolus fractures that extend medially, direct reduction via a posteromedial approach is an alternative operative option. Previous case series (range, 7–17 patients) have demonstrated high rates of fracture healing with good short-term clinical outcomes. The purpose of this study was to report on a large series of posterior malleolus fractures treated via a novel posteromedial approach. The authors hypothesized that fixation of large posterior malleolus fractures with medial extension via a posteromedial approach results in anatomic reduction and stable plate fixation.
Materials and Methods
This study received institutional review board approval. A retrospective review of 244 consecutive operative ankle fractures from 2008 to 2015 identified 22 (9.0%) posterior malleolus fractures treated using a posteromedial approach (Figure 1). All 22 cases were performed by the senior author (L.W.) at 2 institutions. All patients had preoperative CT scans to characterize the posterior malleolus fracture (Figures 2–4). Patient charts were retrospectively reviewed for demographics, injury history, operative details, follow-up time, and any postoperative complications. Postoperative radiographs were reviewed to ensure that anatomic reduction and stable fixation were maintained (Figure 5).
Anteroposterior (A) and lateral (B) radiographs of the right ankle of a 39-year-old woman after a slip-and-fall injury showing a trimalleolar ankle fracture and posterior subluxation of the talus.
Preoperative sagittal computed tomography scan showing a large posterior malleolus fracture.
Preoperative axial computed tomography scan showing a large posterior malleolus fracture with medial extension.
Preoperative computed tomography scan with 3-dimensional reconstruction showing a large posterior malleolus fracture along with medial and lateral malleolus fractures.
Anteroposterior (A) and lateral (B) radiographs of the right ankle obtained approximately 4 months postoperatively demonstrating anatomic reduction and stable plate fixation after open reduction and internal fixation via a posteromedial approach. There is a one-third, 5-hole tubular plate on the posteromedial aspect of the tibial plafond with 2 bicortical screws going posterior to anterior.
Regarding operative technique, the patient is positioned supine on the operating room table. A tourniquet is applied to the operative extremity and inflated before skin incision. Prior to fixation of the posterior malleolus, a direct lateral incision is made, and the fibula is reduced and brought out to length. This can indirectly reduce the posterior malleolus via ligamentotaxis and the PITFL. A posterome-dial incision is then made approximately 6 cm above the ankle joint that curves around the posterior aspect of the medial malleolus. Full-thickness skin flaps are elevated, and dissection is carried down to the tibialis posterior tendon. The tibialis posterior tendon is mobilized, retracted posteriorly, and lifted out of the groove in the posteromedial tibia for better exposure. The posterior malleolus is then reduced under direct visualization and fixated with a plate and screws (Figure 6). If there is a medial malleolus fracture, the posteromedial incision is used, and dissection is carried out anteriorly to gain access to the fracture site for fixation. The sheath of the tibialis posterior tendon is reconstituted, and a tensionless closure of the skin is performed. A splint in neutral position is applied, and patients are kept non–weight bearing for 6 weeks.
Intraoperative photographs of open reduction and internal fixation of a posterior malleolus fracture via a posteromedial approach. The patient is supine on the operating room table. A posteromedial incision is made 6 cm above the ankle joint and curves around the posterior aspect of the medial malleolus (A). Dissection is carried down to the interval between the saphenous vein and the tibialis posterior tendon (B). The tendon is released and retracted posteriorly. A plate is then selected and applied on the posteromedial surface of the tibia (C, D). Under direct visualization of the fracture, posterior to anterior screws are implanted through the plate (E, F).
Sixteen (72.7%) of 22 of the patients were female, and the average age at the time of surgery was 54.1 years (range, 26–86 years). There were no open fractures, but 7 (31.8%) of 22 patients required external fixation prior to open reduction and internal fixation (ORIF) for soft tissue management. The average follow-up time was 13.0 months (range, 2.0–41.4 months). Twenty-one (95.5%) of 22 of the patients healed on a radiographic and clinical basis. Anatomic reduction and stable plate fixation were obtained intraoperatively in all patients and maintained at maximal follow-up in all but 1 patient. Eight (36.4%) patients underwent removal of hardware. There was an 18.2% (4 of 22) postoperative complication rate: 1 patient had cellulitis, 1 patient had osteomyelitis involving the fibula, 1 patient had nonunion requiring revision ORIF, and 1 patient had symptomatic heterotopic ossification. All complications resolved with appropriate management.
The decision to fix posterior malleolus fractures varies greatly among orthopedic surgeons.5 Most surgeons will opt to fix a fragment that is greater than 25% to 30% of the joint surface.1,6 Large posterior malleolus fractures decrease the remaining contact area and increase concentration of loads across the tibiotalar joint, which may result in posttraumatic arthrosis.7 The fibula and anterior inferior tibiofibular ligament are the primary restraints to posterior translation of the talus.8 The loss of ligamentous and bony restraints in trimalleolar fractures can lead to posterior subluxation of the talus and joint instability. If there is still posterior instability after fibula reduction, then fixing the posterior malleolus can help provide a bony restraint against translation. In addition, anatomic reduction of posterior malleolus fractures can restore syndesmotic stability by preventing posterior translation of the fibula through an intact PITFL.9,10 Thus, the primary goals of operative fixation are to restore articular congruity, joint stability, and syndesmotic stability.
The use of CT scans in evaluating trimalleolar fractures has helped to characterize different posterior malleolus fracture patterns.11 The most common type involves the posterolateral corner of the tibial plafond. These fragments can often be reduced indirectly with fibula reduction and ligamentotaxis alone. However, large posterior malleolus fractures that extend medially can present a challenge, especially if they consist of 2 fragments: 1 posteromedial and 1 posterolateral (Figures 2–4). The posteromedial fragment cannot be reduced by fibular reduction because it is not attached to the PITFL. For this reason, providing fixation of the posteromedial fragment in addition to fibular reduction is important in restoring the joint surface and stability.12 Ultimately, the morphology of the fracture determined on CT scan may provide more meaningful information than the size of the fragment alone.
In this series, ORIF of large medial extension–type posterior malleolus fractures via a posteromedial approach achieved anatomic reduction, stable plate fixation, and complete healing in all but 1 patient. The posteromedial approach enables direct visualization and anatomic reduction of large posterior malleolus fractures. In addition, relative to prone patient positioning in the posterolateral approach, supine positioning in the posteromedial approach allows for excellent visualization of the ankle joint, and easy access to the medial malleolus is maintained. Finally, mobilizing the tibialis posterior tendon posteriorly enables retraction of all flexor tendons and the neurovascular bundle as 1 unit to facilitate safe and direct access to the fracture site involving the posteromedial aspect of the distal tibia (Figure 6).
Although problematic, the complications associated with the current series are known risks of orthopedic trauma surgery and not necessarily specific to the authors' fixation technique. The authors believe the high rate of hardware removal (36.4%) in this series was due to their fairly active patient population and geographical tendencies. In this urban environment, patients tend to walk more frequently and are more prone to developing symptomatic hardware. The authors do not think that plating of the posteromedial aspect of the distal tibia generates more painful hardware symptoms than other fixation approaches for ankle fractures.
The current operative technique differs from previously described operative techniques because it involves retracting the tibialis posterior tendon posteriorly instead of anteriorly. In a case series of 17 patients with large posterior malleolus fractures, Bois and Dust13 treated 15 patients with a posteromedial approach and 2 patients with a combined posteromedial and posterolateral approach. Their posteromedial approach was performed with the patient supine and used the interval between the tibialis posterior tendon and flexor digitorum longus. In 12 patients at an average follow-up of 9.4 years, the average global foot and ankle score was 87 points (range, 67–100), and the degree of arthrosis was grade 0 in 3 ankles, grade I in 1 ankle, grade II in 5 ankles, and grade III in 3 ankles. Two patients had peroneal nerve sensory deficits. Bois and Dust13 concluded that a posteromedial operative approach for large posterior malleolus fractures that involved the entire distal tibial plafond could result in good short-and mid-term clinical outcomes.
In contrast, Weber12 used a combined posteromedial and posterolateral approach with the patient in prone position in 9 patients with posterior malleolus fractures involving the entire width of the tibial plafond. They used a standard posterolateral approach between the peroneal tendons and flexor hallucis longus. However, if the fracture was not reducible from their posterolateral approach, a posteromedial incision was made, and the fragment was fixed around its periphery with multiple plates and screws. Weber12 emphasized the importance of not violating the tibialis posterior tendon and groove to avoid devascularizing the fragment. All fractures healed, and 1 patient had moderate loss of joint space.
Interestingly, 1 patient in the series by Weber12 with a posterior malleolus fracture with both medial and lateral fragments only had posterolateral fixation, which resulted in a malunion and posterior instability and subluxation of the talus. This patient eventually required an osteotomy of the posteromedial fragment and revision ORIF. This complication underscores the importance of posteromedial fixation to restore joint congruity and preserve ankle stability.
There were several limitations to this study. Patient outcome scores were not reported. Due to the different morphology of these fractures and the diversity of the patient population, the authors thought that outcome scores would be more dependent on the severity of the trauma rather than the operative technique itself. In addition, the authors cannot definitively state that their posteromedial approach is superior to other posteromedial approaches described in other studies. The authors are also unable to conclude that a posteromedial approach is superior to a posterolateral or anterior approach for treating posterior malleolus fractures. Although they believe that there are several advantages associated with direct reduction and visualization via a posteromedial approach, there is currently insufficient evidence to reach this conclusion.
A randomized, controlled trial comparing anterior, posterolateral, and posteromedial approaches would provide meaningful results. However, this would require a larger number of patients to ensure that the study was well powered. In addition, the variety in posterior malleolus fracture morphology would make it difficult to standardize treatment groups.
In concurrence with previous literature, this study demonstrates that the posteromedial approach is a reasonable alternative to other more commonly used methods for treating these fractures. Posteromedial fixation is especially important in medial extension–type posterior malleolus fractures that cannot be reduced indirectly via fibular reduction and ligamentotaxis.
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