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Posterior talar morphology as a risk factor for bony posterior ankle impingement syndrome: A propensity score-matched cohort study

Year: 2026

Type: article

Abstract: Background: Bony posterior ankle impingement syndrome (PAIS) is associated with posterior talar morphology, including os trigonum and Stieda's process. However, whether these anatomical variations independently contribute to PAIS development remains unclear. This study aimed to investigate the independent association between posterior talar morphology and bony PAIS development using a propensity score-matched cohort design. Methods: This retrospective cohort study included 752 lateral ankle radiographs of patients aged 13-65 years between April 2018 and April 2021. Posterior talar morphology was classified as Group Ⅰ (os trigonum), Group II (isolated Stieda's process), Group III (large Stieda's process without separation from the talus), and Group IV (no posterior deformity). To control for confounding by age and sex, 1:4 propensity score matching was performed. The association between posterior talar morphology and bony PAIS was evaluated using conditional logistic regression adjusted for sports participation. Interrater reliability was assessed using Cohen's kappa coefficient. Results: Eighteen bony PAIS cases were matched to 72 controls. Adequate balance was achieved for age and sex (SMD<0.1). Interrater reliability was substantial (kappa = 0.633, p < 0.001). Os trigonum and isolated Stieda's process (Groups I and II) were significantly associated with bony PAIS (OR = 10.49, 95% CI 2.76-39.81, p < 0.001). Sports participation was not independently associated with bony PAIS (OR = 1.18, 95% CI 0.13-10.73, p = 0.884). Conclusions: Os trigonum and isolated Stieda's process were independently associated with an approximately 10-fold increased risk of bony PAIS, though these findings should be interpreted with caution given the limited number of cases. Patients with these morphological variants engaging in repetitive plantar flexion activities should be carefully monitored.

Source: Asia-Pacific Journal of Sports Medicine Arthroscopy Rehabilitation and Technology

DOI: 10.1016/j.asmart.2026.10.005