In this study, clinical and radiological results after lateral column lengthening by calcaneocuboid distraction arthrodesis and calcaneus osteotomy were compared. Thirty-three patients (35 feet) treated with lateral column lengthening by distraction arthrodesis (14 patients, 16 feet; group I) or by calcaneus osteotomy (19 patients, 19 feet; group II) for adult-acquired flatfoot deformity caused by stage II posterior tibial tendon dysfunction were compared retrospectively. Mean follow-up was 42.4 months (range, 6-78 months) for group I and 15.8 months (range, 6-32 months) for group II (P < .001). The American Orthopaedic Foot & Ankle Society ankle-hindfoot score was determined, 4 variables were measured on preoperative and postoperative weight-bearing radiographs, and a number of independent and outcome variables, including patient satisfaction, were recorded. Group 2 had a significantly higher American Orthopaedic Foot & Ankle Society score compared with group I (mean, 85 vs. 72, respectively; P < .02) at time of last follow-up, and there were no dissatisfied patients in group I, whereas 2 patients in group II were dissatisfied with the result of the operation. All radiological results were significantly better at time of follow-up in both groups (except for talocalcaneal angle in group I), although no significant differences were noted in the amount of change in radiographic measurements between the groups. No significant correlation was found between follow-up time and radiographic improvement, indicating stable radiographic measurements over time. In group II, 13 mild calcaneocuboid subluxations were observed. In both groups, 1 nonunion and 1 wound complication occurred. Based on our experience with the patients described in this report, we recommend lateral column lengthening by means of calcaneus osteotomy rather than distraction arthrodesis of the calcaneocuboid joint, for correction of stage II posterior tibial tendon dysfunction. (C) 2010 by the American College of Foot and Ankle Surgeons. All rights reserved.