Table 3 In- and exclusion criteria for the randomization procedure of the delphi trial.

• Rheumatoid Arthritis patients

• Ranawat IIIA and IIIB: neurological impairment

• Age 18–70

• Severe comorbidity

• Ranawat I and II: no neurological impairment

• Previous cervical surgery

• C1–C2 subluxation:

• C1–C2 subluxation: AADI smaller or larger than the randomization range

   AADI: 5–8 mm

   AADI: 5–12 mm

   AADI: 8–12 mm

• C1–C2 subluxation reducible or irreducible

• MRI incompatibility

• Informed consent