The effect of primary fracture line location on the pattern and severity of intraarticular calcaneal fractures: a retrospective radiographic study.

This retrospective radiographic study sought to evaluate how primary fracture line location relates to the pattern and severity of intraarticular calcaneal fractures. Preoperative lateral radiographs and semicoronal computed tomography scans of 100 displaced intraarticular calcaneal fractures (89 patients) were evaluated for Bohler's angle, Sanders classification, and calcaneocuboid, anterior, or middle subtalar articular involvement. Primary fracture line location was measured on semicoronal computed tomography views as a ratio of the width of the posterior facet. There were 60 Sanders type II (29 IIA, 29 IIB, 2 IIC), 35 type III (10 IIIAB, 9 IIIAC, 16 IIIBC) and 5 type IV fractures. The mean Bohler's angle was 10.1+/-15.6 degrees. The mean primary fracture line location was calculated to be found at 45.7+/-18.2% of the width of the posterior facet, as measured from lateral to medial. Statistical analysis found a significant association between primary fracture line location and Sanders class (r=.636; P<.001) and Bohler's angle (r=-.287; P=.005); as the fracture line moved medially, comminution increased and Bohler's angle decreased. Forty-eight percent of the fractures involved the calcaneocuboid joint; 39% involved the anterior (n=28) or middle (n=11) subtalar facets, or both. A medial primary fracture line correlated to greater involvement of the calcaneocuboid joint (r=.247; P=.015) and the anterior (r=.241; P<.001) and middle (r=.344; P=.003) facets. These results suggest that intraarticular calcaneal fractures exhibiting a medial primary fracture line are associated with a more severe fracture pattern and an increased incidence of anterior articular extension.