Peroneal Artery Danger Zone With Syndesmotic Screw Fixation: A Computed Tomography Angiography Study

Additional trans-syndesmotic screws (TSS) are used in "fibula pro-tibia" approach for unstable ankle fractures applied to high-risk patients (diabetes, smoking, osteoporosis, obesity). These patients are at higher risk of complications. The peroneal artery (PA) may be at risk with additional TSS fixation. Iatrogenic vascular compromise may explain these postoperative complications. Therefore, this study investigates the range in which the PA and its deep perforating branch (dPA) are at risk with TSS fixation and identifies safe zones to avoid iatrogenic injury in this vulnerable population.

A retrospective analysis of lower extremity computed tomography angiograms (CTAs) was performed (2021-2022) in specified patients with comorbidities who might benefit from multiple syndesmotic screw fixation. CTAs were reformatted in the syndesmotic plane, and the PA was deemed at risk if a templated 3.5-mm syndesmotic screw intersected its course. Measurements were taken from both the tibial plafond and fibular tip and included the level where the PA and dPA branch entered and exited this danger zone.

Ninety-eight CTAs (196 limbs) were analyzed. Seventy-two patients were age ≥ 65 (mean 75, SD 8), 52 had diabetes, 16 were active nicotine users, and 16 had BMI ≥35. The PA was at risk in 98.5% (n = 195) limbs. The danger zone began 7.5 cm (SD 1.5 cm) proximal to the tibial plafond and 10 cm (SD 1.5 cm) proximal to the fibular tip. The dPA branch perforated the syndesmotic plane at 3.6 cm (SD 0.8 cm) proximal from the plafond and 6 cm (SD 0.9 cm) from the fibular tip. Finally, the PA and dPA were out of the danger zone at 2.5 cm (SD 0.4 cm) proximal from the tibial plafond and 5 cm (SD 0.6 cm) from the fibular tip. No difference was found between inclusion subgroups nor between individual patients' contralateral legs.

PA and dPA are at risk with TSS, notably in the distal fifth of the limb, ending ~2.5 cm proximal to the plafond. Knowledge of this zone aids in planning for TSS fixation, especially for high-risk patients.