Question 2: Outcomes of treatment in patients with symptomatic os odontoideum.

Outcomes	Strength of evidence	Conclusions/comments
1. Symptoms		Symptoms were relieved in the majority of cases after fusion. Symptoms were also seen to improve in the majority of nonoperative patients.
2. Fusion success		Fusion was successful in most cases.

Details about the determination of strength of evidence can be found in the web appendix at www.aospine.org/ebsj