Kirschner Wire as a Reference Marker for the Positioning of a Syndesmotic Screw: A Radiological Study and Clinical Evaluation.

Abstract

No consensus has been reached regarding optimal implantation for a syndesmotic screw. Thus, we aimed to explore the feasibility of a reliable and static fibular incisura plane reference for ideal syndesmotic screw placement. A retrospective review of computed tomography (CT) scans of 42 uninjured adult ankles with foot fractures were analyzed to measure the tibiofibular vertical distance (TFVD) at 2.5 cm proximal to the plafond from August 2016 to June 2017 in our hospital. The patients (20 females, 22 males) were divided into four groups according to their TFVD: 0-1, 1-2, 2-3, and 3-4 mm, and patients in each group were counted. We retrospectively assessed 41 patients (15 females, 26 males) who underwent syndesmotic screw fixation for ankle fractures from December 2015 to June 2020. We performed t-testing of two independent samples to determine the differences in the angle between the anatomic axis of the syndesmosis and screw axis (AAS) and ankle function using the American Orthopaedic Foot and Ankle Society (AOFAS) score at 3 and 6 months postoperatively between the conventional (20 patients) and K-wire marker (21 patients) groups. The correlation between the AAS and AOFAS score was analyzed. The TFVD measured 2.23 ± 1.01 mm at 2.5 cm proximal to the plafond, and occurred at 25% of the distance from 2 to 3 mm in 47.6% of the patients. This new technique decreased AAS deformation by 62%, from 13.01° ± 2.84° to 4.89° ± 2.43°, in the conventional group (p<0.001). At 3 months postoperatively, the AOFAS scores of ankle function were similar in both groups, but it was significantly better in the new group than that of conventional group at the 6-month follow-up (p=0.024). There was a moderate negative correlation between AAS and AOFAS score at 6 months postoperatively (R=-0.684). No obvious complications affecting ankle function were observed in either group postoperatively. Surgeons can accurately place a screw trajectory using the fibular incisura plane as a reliable intraoperative reference. A 1.6-mm K-wire placed in the syndesmosis at 2.5 cm proximal to the tibial plafond could act as a static marker of the syndesmotic plane.