Background The coronoid process of the ulna is an important structure for the overall stability of the elbow, because it provides resistance against anterior subluxation of the ulna on the trochlea as well as resistance against varus stress. For anteromedial facet fractures of the coronoid, surgical treatment involves a mix of techniques, including medial buttress plate, screw fixation, suture fixation, and isolated lateral collateral ligament repair. Purpose This video and case presentation demonstrate the technique for surgical repair of anteromedial facet fractures of the coronoid process by using buttress plate fixation. Methods The anatomy of the coronoid process and the classification of coronoid fractures are reviewed. The mechanism of anteromedial facet fractures is detailed, and the resulting posteromedial rotatory elbow instability is described. The case of a 54-year-old man with an anteromedial coronoid facet fracture is used to demonstrate the typical presentation, characteristic imaging findings, preoperative decision-making process, and surgical technique to fix this fracture pattern. Results Access to the coronoid is obtained by using an interval through a split in the flexor pronator mass, termed the over-the-top exposure. A miniature fragment plate is contoured and applied as a buttress anteriorly with reapproximation of the anteromedial facet fragment to the intact portion of the coronoid. Alignment was maintained postoperatively with good functional outcomes. Conclusion Buttress plate fixation of anteromedial facet fractures of the coronoid process restores stability to the elbow and provides good functional outcomes.