Sat., 10/18/08 Foot & Ankle/Pediatrics, Paper #58, 11:26 am OTA-2008
Radiographic Outcomes of Syndesmotic Stabilization via Posterior Malleolar Fixation
Anna N. Miller, MD (n); Eben A. Carroll, MD (n); Robert J. Parker, BS (n);
David L. Helfet, MD (n); Dean G. Lorich, MD (n);
Hospital for Special Surgery, New York, New York, USA
Purpose: Ankle fractures with syndesmosis instability treated with traditional trans-syndesmotic fixation methods have a high percentage of syndesmotic malreduction in our previous study (Gardner et al, 2006). Subsequent to these results, we established a protocol involving a more anatomic reconstruction of the incisura when indicated. This involves direct visualization of the syndesmosis and fixation concentrated on centering the fibula (in the sagittal plane) within the tibial incisura. We compared this group with our historic control, using postoperative ankle CT to determine if a more aggressive and direct means of reconstruction of the syndesmosis resulted in more accurate reduction.
Methods: 149 patients over 4 years with ankle fractures and syndesmotic instability were evaluated. Patients with a posterior malleolar fracture were treated prospectively with meticulous reconstruction of the tibial incisura, regardless of posterior malleolar fragment size. The syndesmosis was opened and débrided before reduction and, under direct visualization, reduced using a pelvic clamp; syndesmotic screws were placed through a one-third tubular plate in a locked fashion, in order to avoid a malreduction force vector with more traditional compression screws. Only patients with a higher-energy soft-tissue injury (ie, fracture-dislocation) had both posterior malleolar and syndesmotic fixation. All patients had postoperative bilateral CT. Axial CT images assessed for syndesmotic reduction by measuring the distance between the fibula and the anterior and posterior facets of the incisura. Differences between anterior and posterior measurements over 2 mm were considered incongruous. These “anatomic” reduction patients were compared with 25 patients fixed prior (“control”), with syndesmotic reduction performed via intraoperative fluoroscopy (no direct visualization).
Results: In the anatomic reduction group, 24 ankles (16.0%) had incongruity of the fibula on CT (average 2.75 mm). In 75% of the malreductions, the posterior measurement was greater, indicating that internal rotation or anterior translation of the fibula may have occurred. In the control group (fluoroscopic reduction), 13 patients (52%) had incongruity (average 3.6 mm). In 77% of the malreductions, the posterior measurement was greater. Patients were divided into three groups based on type of fixation: posterior malleolus (PM), syndesmosis (S), and combination syndesmosis with posterior malleolus fixation (C). The average difference between anterior and posterior colliculi measurements for each group were as follows: PM, 0.82 mm; S, 1.13 mm; and C, 1.42 mm. The C and PM groups were statistically significantly different, and S and PM trended toward significance. In addition, only one of the PM group was incongruous (2.7%), compared to 18.8% incongruence of the S group, and 31.3% of C.
Conclusion and Significance: In our cohort, malreductions were significantly decreased in the anatomic incisura re-creation and direct syndesmotic visualization group compared with our historic controls. In addition, this technique is more accurate than syndesmotic screw fixation alone. We also found a high tendency to internally rotate the fibula, especially in the syndesmotic screw fixation group. Open anatomic reconstruction of the posterior malleolus and posteroinferior tibiofibular ligament for syndesmosis injury is a significant improvement over syndesmotic screw fixation and indirect reduction.
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• The FDA has not cleared this drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed for an “off label” use). ◆FDA information not available at time of printing. Δ OTA Grant.