We reviewed 364 consecutive cases of operatively treated ankle fractures that included fixation of the syndesmosis. Based on postoperative radiographs and computed tomography (CT) scans (in two patients), we identified three patients with anterior subluxation of the talus after placement of a syndesmotic screw. All three patients had a Weber C/Maisonneuve pattern of injury: two had an associated deltoid ligament rupture and the third patient had a complex medial malleolar fracture. The malreduction was identified on postoperative radiographs, and all patients underwent successful revision surgery. The salient features of each case are summarized in Table I.
Case 1. A twenty-nine-year-old woman sustained an external rotation injury to the left ankle while wrestling. Radiographs demonstrated a Weber C/Maisonneuve injury that included a deltoid ligament rupture, syndesmosis disruption, and fracture of the proximal part of the fibula (Figs. 1-A and 1-B). Intraoperatively, an external rotation stress test demonstrated a grossly unstable ankle with near dislocation of the talus. No reduction of the fracture of the proximal part of the fibula was attempted. With the ankle held in dorsiflexion, a closed reduction of the syndesmosis was performed with use of a large reduction tenaculum to reduce the fibula within the incisura fibularis. Through stab incisions, two quadricortical 3.5-mm fully threaded screws were placed parallel to the ankle joint. Both screws were placed percutaneously in neutralization-position mode.
A postoperative review of the intraoperative fluoroscopic images demonstrated anterior subluxation of the talus relative to the tibia on the lateral view (Fig. 2). The anterior joint space measured 1.8 mm, and the posterior joint space measured 3.6 mm. A postoperative CT scan confirmed anterior subluxation of the talus, and demonstrated malreduction of the syndesmosis with anterior translation of the fibula (Figs. 3-A and 3-B). On postoperative day three, the patient was returned to the operating room for a revision closed reduction of the syndesmosis and a change of the transsyndesmotic screw trajectory.
Case 2. A thirty-six-year-old man was jumping for a basketball when he landed awkwardly, twisting the right ankle. The patient could not remember the exact position of the foot at the time of injury. Radiographs demonstrated a Weber C/Maisonneuve ankle injury with a high fibular fracture and widening of the medial and tibiofibular clear spaces (Figs. 4-A and 4-B).
Under anesthesia, a closed reduction of the syndesmosis was performed with a large reduction tenaculum. No attempt at fibular fracture reduction was made. There was also no attempt to keep the ankle in dorsiflexion when performing the closed reduction. Two 3.5-mm fully threaded cortical screws were placed parallel to the ankle through four cortices.
Postoperative radiographs demonstrated anterior subluxation of the talus (Figs. 5-A and 5-B). On the lateral radiograph, the anterior joint space measured 3.2 mm, while the posterior joint space measured 6.7 mm. These radiographs provided conclusive evidence of malreduction, and, therefore, a CT scan was not obtained. On postoperative day three, the patient was brought back to the operating room for a revision closed reduction of the syndesmosis and a change of trajectory of the transsyndesmotic screws.
Case 3. A twenty-four-year-old man sustained a right ankle injury while playing soccer. The patient presented with a posterior ankle dislocation, and he underwent a closed reduction in the emergency department. The patient was diagnosed with a Weber C/Maisonneuve ankle injury with a complex medial malleolar fracture consisting of a distal anterior collicular fracture with proximal extra-articular comminution (Fig. 6).
Under anesthesia, two large reduction tenaculums were used to perform a closed reduction of the syndesmosis. No fibular fracture reduction was attempted. Two parallel 3.5-mm fully threaded cortical screws were placed across the syndesmosis with purchase in four cortices. The anterior collicular medial malleolar fragment was not felt to provide a substantial contribution to joint stability and was not fixed.
Postoperative radiographs demonstrated mild widening of the medial clear space (Figs. 7-A and 7-B), and anterior subluxation of the talus can be seen on the lateral radiograph. Additionally, anterior placement of the syndesmotic screws was demonstrated on the lateral radiograph. A CT scan was obtained that showed anterior subluxation of the talus on the sagittal images, with an anterior joint space measuring 1.9 mm and a posterior joint space measuring 3.5 mm (Figs. 8-A and 8-B). The CT scan also confirmed that the syndesmotic screws were malpositioned and prominent medially, with an associated anterior translation of the fibula within the syndesmosis. The malreduction of the syndesmosis and tibiotalar joint was discovered on the patient’s follow-up visit at three weeks, and he was returned to the operating room for open reduction of the syndesmosis, debridement of the medial gutter, and placement of two new transsyndesmotic screws.
To our knowledge, this is the first description of malreduction of the tibiotalar joint in the sagittal plane as a result of syndesmosis malreduction. Accounting for radiograph magnification, we found that the posterior joint space was at least 1.8 times as wide as the anterior joint space with the ankle in a neutral position in all three patients (Table I).
A common theme was present with regard to the injury pattern as well as the approach to reduction and fixation. In each case, the fibular fracture was not addressed, and a closed reduction of the syndesmosis was performed with use of a large reduction tenaculum. This resulted in the talus subluxating anteriorly, even in the presence of an initial posterior dislocation (Case 3), despite the absence of osseous injury to the anterior column. This complication was observed in Weber C/Maisonneuve injuries, but not in Weber B/supination-external rotation ankle fractures that require syndesmosis stabilization after a positive intraoperative stress test.
It is unclear how malreduction of the syndesmosis leads to subluxation of the tibiotalar joint. The malreduction of the distal tibiofibular joint likely causes a change in morphology of the highly conforming ankle mortise. Since the trapezoidal-shaped talus no longer fits precisely in the mortise, it must translate anteriorly and externally rotate to allow the narrower posterior talar body to reside in the mortise. Additional biomechanical studies are needed to elucidate the exact position of the malreduced talus, as well as the location and magnitude of increased contact pressures.
As a result of these three cases of syndesmosis malreduction following closed reduction, our approach to surgical treatment of injuries to the syndesmosis has evolved. Obtaining an anatomic reduction of the syndesmosis starts with restoration of the length and rotation of the fibula. To achieve these goals, we now reduce and fix any fibular fracture that is in the distal half of the bone. Pelton et al. have extended this indication to fractures of the proximal part of the fibula, and they have reported improved accuracy of the reduction of the syndesmosis9. Given the reported high incidence of malreduction with use of closed means3,4, we also now perform an open reduction of the syndesmosis. If a fracture of the distal part of the fibula is present, then the incision and exposure is moved slightly anterior to allow concomitant visualization of the syndesmosis. When performing open reduction and internal fixation of a midshaft fibular fracture, a small 3-cm separate distal incision is made to facilitate syndesmosis reduction and screw placement. If a fibular neck fracture results in shortening or rotation of the distal part of the fibula, then we utilize indirect reduction techniques to reduce the proximal part of the fracture, combined with an open reduction of the syndesmosis. A small pointed tenaculum is used to grasp the distal part of the fibula to provide traction and rotational control. These indirect reduction methods avoid the risk of peroneal nerve injury with dissection about the fibular neck. In the case of a large posterior malleolar fracture, we use a posterolateral approach to perform an open reduction and internal fixation of the posterior malleolous and use supplementation with a transsyndesmotic screw on an individualized basis. Transsyndesmotic screws are not routinely removed, although patients are counseled about the possibility of screw breakage. If the patient requests screw removal, it is performed more than six months following the initial surgery to allow for full ligamentous healing.
We now rarely use reduction clamps to achieve a closed reduction of the syndesmosis. However, if this method is chosen, then a number of technical modifications may increase the likelihood of an anatomic reduction. First, a towel bump should be placed under the patient’s leg, proximal to the ankle joint to prevent an anterior translational force on the foot. Second, placement of reduction clamps must be meticulous. Adequate exposure of the fibula is required to ensure that the clamp is on the direct lateral border of the fibula. If the clamp is posterior or anterior, then a rotational and/or translational force will be applied to the syndesmosis as it is tightened. Most commonly, the clamp slips posteriorly, resulting in anterior translation and external rotation of the fibula within the syndesmosis. This may result in anterior translation of the talus, as was seen in all three of our patients. Additionally, the clamp must be placed perfectly perpendicular to the syndesmosis. To achieve pure compression of the syndesmosis, the clamp should be placed on the direct lateral surface of the fibula and the direct medial surface of the medial malleolus, resulting in the tines being externally rotated 30° relative to the floor.
In conclusion, we report anterior subluxation of the talus as a newly recognized complication of syndesmosis malreduction. To avoid this complication, the surgeon must restore proper fibular length and rotation and may perform an open reduction of the syndesmosis to facilitate anatomic reduction. Finally, after placement of a transsyndesmotic screw, a perfect lateral radiographic image should be obtained to measure the anterior and posterior joint spaces in order to rule out subtle subluxation of the talus.
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.