Is the distal tibial slope associated with medial osteochondral lesions of the talus? a radiographic case-control study

Background Medial osteochondral lesions of the talus (OLT) are a recognized cause of chronic ankle pain, yet the morphologic factors associated with them remain incompletely understood. We hypothesized that distal tibial slope measured on weight-bearing lateral ankle radiographs would be lower in patients with medial OLT than in controls. Methods In this retrospective case-control study, 76 patients with medial OLT confirmed on magnetic resonance imaging and 170 control subjects without OLT were included. Distal tibial slope was calculated from the anatomic anterior distal tibial angle on weight-bearing lateral radiographs. Univariable and multivariable (age- and sex-adjusted) logistic regression and receiver operating characteristic (ROC) analyses with bootstrap internal validation were performed. Results Distal tibial slope was lower in the medial OLT group than in controls (median 5.1° [IQR 3.5–6.8] vs. 6.6° [IQR 5.0–8.8], P < .001). After adjustment for age and sex, each 1° decrease in distal tibial slope was associated with higher odds of medial OLT (adjusted OR 1.28; 95% CI 1.14–1.44). The area under the ROC curve was 0.67 (95% CI 0.59–0.74). An exploratory, study-specific cut-off of ≤ 4.6°, derived from the same sample, was associated with higher odds of medial OLT (adjusted OR 3.24; 95% CI 1.80–5.82), with a sensitivity of 47.4% and a specificity of 77.1% (bootstrap-corrected, 43.5% and 76.1%, respectively). Conclusions A lower distal tibial slope on weight-bearing lateral radiographs was associated with the presence of medial OLT. Given its modest discriminatory performance and the exploratory, study-specific nature of the cut-off, distal tibial slope should not be regarded as a diagnostic or screening criterion. Whether this finding represents a predisposing morphology requires confirmation in prospective and biomechanical studies.