Objective: To define the relationship between postoperative congruency of the posterior facet of the subtalar joint based on computed tomography (CT) and clinical results.
Design: Preoperative and postoperative CT scans were taken prospectively and analyzed.
Setting: University medical center.
Patients: Twenty-nine displaced fractures in twenty-five patients.
Intervention: All patients were treated with open reduction and internal fixation without bone graft.
Main outcome measures: Postoperative CT findings were classified into three groups, according to the degree of displacement: anatomic, no displacement; nearly anatomic, displaced less than two millimeters; and approximate, displaced more than two millimeters.
Results: The reduction state after operative treatment for the cases with more comminution showed worse results when analyzed in both preoperative and postoperative CT scans. Fifteen of seventeen fractures (88 percent) with anatomic reduction and seven of eight fractures (87 percent) with nearly anatomic reduction had excellent or good clinical results. In contrast, no fracture with an approximate reduction had an excellent result.
Conclusion: An excellent or good clinical result can be expected when the postoperative displacement of the posterior facet of the subtalar joint is less than two millimeters.