Ranawat criterion
The Ranawat Criterion is the distance between the center of the C2 pedicle and the transverse axis of C1 measured along the axis of the odontoid process. 1).
Cervical spine is the third most common location of lesions in the course of rheumatoid arthritis. Pathological lesions in cervical spine structure are observed in 44–86% of patients with RA
1)
Ranawat CS, O'Leary P, Pellicci P, et al. Cervical Spine Fusion in Rheumatoid Arthritis. J Bone Joint Surg. 1979; 61A:1003–1010