Background: Without a reliable and static reference, the rate of eccentrically positioned distal syndesmotic screw is very high. This article describes an additional method to improve surgeons’ ability to ideally place this screw. The purposes of our study were (1) to determine if an ideal space at 2.5 cm proximal to the plafond existed between the tibia and fibula for the placement of a Kirschner (K) wire and (2) to detect if it could act as a reliable and static fibular incisura plane reference.
Methods: Computed tomography (CT) scans of 42 uninjured adult ankles with foot fractures were analysed to measure the tibiofibular vertical distance (TFVD) at 2.5 cm proximal to the plafond on transverse images. TFVD was defined as the distance between two lines: Line 1 was tangent to the fibular incisura, and Line 2 was parallel to Line 1 along the medial fibula. Patients were divided into four groups according to our TFVD data: 0–1, 1–2, 2–3, and 3–4 mm, and the number of patients in each group was counted. We assessed 23 patients who underwent syndesmotic screw fixation for ankle fractures. Comparison of the angle between the anatomic axis of the syndesmosis and screw axis (AAS) was performed between patients using conventional method (11 patients) and with K-wire marker (12 patients).
Results: TFVD measured 2.23 ± 1.01 mm at 2.5 cm proximal to the plafond. TFVD occurred at 25% of the distance from 2 to 3 mm in 47.6% of patients. This new technique decreased the deformation of AAS by 75%, from 13.06 ± 2.55° to 4.28 ± 1.72°, in the conventional group.
Conclusions: Placing a 1.6-mm K-wire in the syndesmosis at 2.5 cm proximal to the tibial plafond is easy because of emerging TFVDs. Compared to the conventional method, this new technique increased the accuracy of syndesmotic screw placement by up to 75 percent. Therefore, K-wire could be used as a reliable and static intraoperative reference of the fibular incisura plane through which surgeons can accurately place a screw trajectory.