Association between distal tibial slope and posterior talar variations (Stieda process and os trigonum): A...

Posterior talar variations, including the Stieda process (SP) and os trigonum (OT), are anatomic variants commonly associated with posterior ankle impingement, but their relationship with sagittal plane ankle morphology, particularly the distal tibial slope (DTS), remains poorly investigated.

To evaluate the association between posterior talar variations and DTS from a morphologic perspective.

Retrospective comparative study.

Weight-bearing lateral ankle radiographs of 259 patients with ankle pain (2018-2023) were retrospectively reviewed, including 129 with posterior talar variations and 130 controls. DTS was pre-specified as the primary outcome and other radiographic foot morphology variables as exploratory secondary outcomes.

DTS was significantly lower in patients with posterior talar variations than in controls (median, 5.30° vs 7.35°; p < .001). Each 1° decrease in DTS was associated with increased odds of posterior talar variation (OR, 1.40; 95% CI, 1.25-1.57). Subgroup analysis showed significantly lower DTS in both the SP and OT groups, and the Gissane angle was higher only in the SP group. The absolute between-group difference was numerically modest and should be regarded as descriptive.

DTS was significantly lower in individuals with posterior talar variations, with a cutoff value of ≤ 6.9° (sensitivity 79.8%, specificity 57.7%) showing moderate discriminatory ability. As the difference was modest and clinical outcomes were not assessed, the findings are exploratory and hypothesis-generating, suggesting that posterior talar variations may be considered within sagittal plane ankle morphology rather than as isolated structures. Prospective clinical and biomechanical studies are needed.