Which type of supra-syndesmal fractures Weber C or Equivalent Weber C have the best reduction of the distal tibio-fibular syndesmosis? A prospective CT-scan investigation on 60 ankles.

Introduction: The reduction of the distal tibiofibular syndesmosis (SyTFd) is a crucial factor in the functional prognosis following a suprasyndesmotic ankle fracture. Few studies have compared, using computed tomography (CT), the quality of SyTFd reduction in Weber C ankle fractures (WebC) and Equivalent Weber C (EqWebC) fractures, where there is a medial ligament injury instead of a bony malleolar lesion. This CT-based study aimed to answer the following questions: (1) Do Weber C fractures allow for better reduction of the distal tibiofibular syndesmosis compared to Equivalent Weber C fractures? (2) Are the functional outcomes one year postoperatively better for Weber C fractures compared to Equivalent Weber C fractures?

Hypothesis: The hypothesis was that WebC fractures would present better reduction of the SyTFd than EqWebC fractures due to the restoration of bone anatomy, considering the bony nature of the medial ligament involvement.

Materials and methods: Since December 2021, all patients presenting with an ankle fracture were included in a database. Suprasyndesmotic fractures were extracted, and between December 2021 and February 2022, 60 patients underwent surgery for a suprasyndesmotic fracture (28 WebC - 32 EqWebC). All patients were operated on using the same technique and underwent a postoperative bilateral CT scan in axial slices with both ankles in a neutral position (foot at 90 ° to the leg). An analysis of 8 measurements was performed under the same conditions. Each fractured ankle was compared to the healthy contralateral ankle, and a delta was obtained for each measurement. The follow-up was standardized. At one year, an AOFAS Score and a Maryland Foot Score (MFS) were recorded. Statistical differences between the two groups were measured using the Student's t-test and Chi-square test.

Results: There was a significant difference between the WebC and EqWebC groups for clinical scores at one year postoperatively: AOFAS: 92.0 ± 6.3 [78-100] vs. 80.1 ± 5.4 [62-100], p < 0.05; MFS: 90.9 ± 6.4 [78-100] vs. 81.6 ± 5.2 [64-100], p < 0.05. CT scan analysis of the SyTFd reduction found significantly better reduction in the WebC group.

Discussion: WebC fractures showed better clinical scores associated with better SyTFd reduction on postoperative CT scans. The anatomical reduction related to the bone reduction criteria during surgery could explain our findings.

Level of evidence: III; Case-Control Comparative Study.