Using the Equatorial Talar Line as a Radiographic Predictor of Sanders Type 3 and 4 Calcaneus Fractures and Lateral Wall Blowout.

Objective: To assess the equatorial talar line (ETL) as a sensitive radiographic parameter to predict Sanders type III and IV fractures and the presence of lateral wall blowout.

Methods: Reliability of the ETL was assessed using the intraclass correlation coefficient (ICC) and receiver operating curve (ROC) to predict sensitivity. Using lateral ankle radiographs, raters determined whether the calcaneal tuberosity was "above" (predicting Sanders type I or II) or "below" (predicting Sanders type III or IV and lateral wall blowout).

Results: In determining the "above" or "below" location of the ETL, the calculated ICC was 1.0 for each session. As a predictor of Sanders fracture classification type, the calculated ICC was 0.93 for the first session and 0.89 for the second session for an overall ICC of 0.91. As a predictor of Sanders fracture type, ROC analysis yielded an overall sensitivity of 0.82. As a predictor of lateral wall blowout, ROC analysis yielded an overall sensitivity of 0.81.

Conclusion: The ETL is a reproducible radiographic parameter that can be reliably used to crudely predict between Sanders type I or II (ETL is "above") and Sanders type III or IV (ETL is "below") calcaneus fractures as well as the presence of lateral wall blowout.