Background: Opening wedge osteotomy of the medial cuneiform has become an established intervention for correction of forefoot varus in relation to a flatfoot deformity. The purpose of this study was to use a newly described radiographic measurement to determine the effectiveness and durability of the medial column correction with a plantarflexion opening wedge osteotomy of the medial cuneiform without internal fixation using an allograft. Methods: Twenty-three feet underwent medial cuneiform opening wedge osteotomies for correction of forefoot varus associated with flatfoot deformity. The angle between the proximal and distal articular surfaces was measured on lateral radiographs preoperatively, postoperatively prior to weightbearing and at final followup visit. Results: The average angle between the proximal and distal articular surfaces of the medial cuneiform on lateral foot radiographs was 1.0 degree preoperatively (±0.8 degrees). The average angle postosteotomy, pre-weightbearing, was 8.4 degrees (±3.6 degrees) and at final followup was 7.5 degrees (±2.9 degrees). All patients achieved bony union. Conclusion: We describe a new radiographic measurement to focus on the correction achieved by a plantarflexion osteotomy of the medial cuneiform. It was found to be stable without internal fixation and reliably proceeded to union without significant loss of correction. Level of Evidence: IV, Retrospective Case Series