Failure of Miniplate Fixation in a Fracture of the Mandibular Coronoid Process

Mandibular coronoid fractures are mainly the result of motor vehicle accidents, followed by assaults and falls. We report a case of failure of miniplate fixation in a coronoid fracture. A 57-year-old man fell onto his face from a 3-m height. Panoramic radiography and computed tomography confirmed a right tripod fracture, a LeFort I fracture, and a right coronoid process fracture. On day 6 posttrauma, open reduction and miniplate fixation were performed. Instead of performing intermaxillary fixation, we recommended consumption of a soft diet for at least 1 month. On postoperative day 30, while opening his mouth to eat, the patient felt a strange sensation in his right cheek and heard a clicking sound. He then began to feel pain and had difficulty chewing. On postoperative day 40, follow-up panoramic radiography revealed breakdown of the previously fixed miniplate. Pain and difficulty chewing continued, and coronoidectomy and plate removal were performed at 18 months postoperatively. It is thought that a miniplate large enough to withstand the pull of the temporalis muscle should not be applied to a fractured coronoid process due to the shallow anterior border of the coronoid process. Although the patient’s quality of life, feeding and oral hygiene care are a big burden of care in postoperative intermaxillary fixation, rigid internal fixation and intermaxillary fixation for at least 1 month are recommended in patients with significant displacement of a fractured coronoid process or limited mouth opening.