Non-rigid immobilisation of odontoid fractures

Despite various reports on the management of odontoid fractures, there is no consensus on the subject, and the appropriate treatment still remains controversial. While untreated fractures or fractures treated only with a cervical orthosis seem to have the highest rate of non-union, the need for rigid external stabilisation has never been substantiated. In a retrospective analysis we reviewed 26 patients with acute type II and III fractures of the odontoid, treated with a cervical orthosis only. Study inclusion was limited to fractures that had a fracture gap of less than 2 mm, an initial antero-posterior displacement of less than 5 mm and angulation of less than 11 degrees, less than 2 mm displacement on lateral flexion/extension views, and were without neurological deficits. These fractures were defined as stable. There were 19 (73.1%) type II and 7 (26.9%) type III fractures; in 10 (38.5%) of these fractures the odontoid was displaced and/or angulated. The overall complication rate was 11.4% ( n=3). One patient suffered from pulmonary embolism, in two patients (7.7%) with initially minimally displaced fractures, secondary internal stabilisation had to be performed because of persistent instability. In 20 (77%) of the remaining fractures healing was uneventful. In 4 nondisplaced fractures (15%) fibrous union was documented. Three of these patients were over 65 years old. The overall fusion rate was 73.7% for type II and 85.7% for type III fractures. At follow-up 39% of the patients were free of symptoms; however, the clinical outcome did not correlate with the radiological findings. According to our findings, stable type II and type III fractures of the odontoid can be successfully treated with non-rigid immobilisation, even if they are displaced. A thorough assessment of the stability of the odontoid with lateral flexion/extension views or dynamic fluoroscopy is recommended to evaluate the appropriate treatment. Non-rigid immobilisation may be an option in selected cases with stable injuries.