Table 3.
Sensitivity and specificity of posterior malleolus displacement and magnetic resonance imaging (MRI) deep deltoid findings in detecting trimalleolar equivalent injury patterns
| Sensitivity (%) | Specificity (%) | Positive predictive value (%) | Negative predictive value (%) | |
|---|---|---|---|---|
| Displacement on lateral X-ray | ||||
| ≥ 1 mm | 84.6 | 40.0 | 47.8 | 80.0 |
| ≥ 1.5 mm | 76.9 | 65.0 | 58.8 | 81.3 |
| ≥ 2 mm | 76.9 | 70.0 | 62.5 | 82.4 |
| Partial or complete deep deltoid tear on MRI | ||||
| Entire cohort (n = 33) | 69.2 | 70.0 | 60.0 | 77.8 |
| Subgroupa (n = 17) | 69.2 | 25.0 | 75.0 | 20.0 |
| Complete deep deltoid tear on MRI | ||||
| Entire cohort (n = 33) | 46.2 | 90.0 | 75.0 | 72.0 |
| Subgroup† (n = 17) | 46.2 | 75.0 | 85.7 | 30.0 |
aSubgroup of fractures undergoing direct deltoid ligament visualization