Automated radiography assessment of ankle joint instability using deep learning

This study developed and evaluated a deep learning (DL)-based system for automatically measuring talar tilt and anterior talar translation on weight-bearing ankle radiographs, which are key parameters in diagnosing ankle joint instability. The system was trained and tested using a dataset comprising of 1,452 anteroposterior radiographs (mean age ± standard deviation [SD]: 43.70 ± 22.60 years; age range: 6-87 years; males: 733, females: 719) and 2,984 lateral radiographs (mean age ± SD: 44.37 ± 22.72 years; age range: 6-92 years; male: 1,533, female: 1,451) from a total of 4,000 patients, provided by the National Information Society Agency. Patients who underwent joint fusion, bone grafting, or joint replacement were excluded. Statistical analyses, including correlation coefficient analysis and Bland-Altman plots, were conducted to assess the agreement and consistency between the DL-calculated and clinician-assessed measurements. The system demonstrated high accuracy, with strong correlations for talar tilt (Pearson correlation coefficient [r] = 0.798 (p < .001); intraclass correlation coefficient [ICC] = 0.797 [95% CI 0.74, 0.82]; concordance correlation coefficient [CCC] = 0.796 [95% CI 0.69, 0.85]; mean absolute error [MAE] = 1.088° [95% CI 0.06°, 1.14°]; mean square error [MSE] = 1.780° [95% CI 1.69°, 2.73°]; root mean square error [RMSE] = 1.374° [95% CI 1.31°, 1.44°]; 95% limit of agreement [LoA], 2.0° to - 2.3°) and anterior talar translation (r = .862 (p < .001); ICC = 0.861 [95% CI 0.84, 0.89]; CCC = 0.861 [95% CI 0.86, 0.89]; MAE = 0.468 mm [95% CI 0.42 mm, 0.51 mm]; MSE = 0.551 mm [95% CI 0.49 mm, 0.61 mm]; RMSE = 0.742 mm [95% CI 0.69 mm, 0.79 mm]; 95% LoA, 1.5 mm to - 1.3 mm). These results demonstrate the system's capability to provide objective and reproducible measurements, supporting clinical interpretation of ankle instability in routine radiographic practice.