Effect of type II odontoid fracture nonunion on outcome among elderly patients treated without surgery: Based on the AOSpine north america geriatric odontoid fracture study

STUDY DESIGN.: Subgroup analysis of a prospective multicenter study. OBJECTIVE.: Outcome analysis of nonoperatively treated elderly patients with type II odontoid fractures, including assessment of consequence of a fracture nonunion. SUMMARY OF BACKGROUND DATA.: Odontoid fractures are among the most common fractures in the elderly, and controversy exists regarding treatment. METHODS.: Subgroup analysis of a prospective multicenter study of elderly patients (≥65 yr) with type II odontoid fracture. Neck Disability Index and Short-Form 36 (SF-36) version 2 were collected at baseline and 6 and 12 months. Fifty-eight (36.5%) of the 159 patients were treated nonoperatively. RESULTS.: Of the 58 patients initially treated nonoperatively, 8 died within 90 days and were excluded. Of the remaining 50 patients, 11 (22.0%) developed nonunion, with 7 (63.6%) requiring surgery. Four of the 39 (10.3%) patients classified as having "successful union" required surgery due to late fracture displacement. Thus, 15 (30.0%) patients developed primary or secondary nonunion and 11 (22.0%) required surgery. The overall 12-month mortality was 14.0% (nonunion = 2, union = 5; P= 0.6407). For union and nonunion groups, Neck Disability Index and SF-36 version 2 declined significantly at 12 months compared with preinjury values (P< 0.05), except for SF-36 version 2 Physical Functioning (P= 0.1370). There were no significant differences in outcome parameters based on union status at 12 months (P> 0.05); however, it is important to emphasize that the 12-month outcomes for the nonunion patients reflect the status of the patient after delayed surgical treatment in the majority of these cases. CONCLUSION.: Nonoperative treatment for type II odontoid fracture in the elderly has high rates of nonunion and mortality. Patients with nonunion did not report worse outcomes compared with those who achieved union at 12 months; however, the majority of patients with nonunion required delayed surgical treatment. These findings may prove useful for patients who are not surgical candidates or elect for nonoperative treatment.