Fig. 3

ROC curve of IR angle. The ROC curve analysis suggested the optimum cutoff point for IR angle was 51°, with a sensitivity of 0.5, a specificity of 1.0, a positive likelihood ratio of 9.7, and a negative likelihood ratio of 0.5. The AUC measured 0.8 (p = 0.004, 95%CI 0.6–0.9). When a sensitivity was 0.8, IR angle was 67°, with a specificity of 0.6, a positive likelihood ratio of 2.1, and a negative likelihood ratio of 0.3