The effect of cervical spine flexion-extension motion on odontoid parameters

OI is a stable and reliable anatomic parameter, not affected by cervical spine flexion-extension motion. OI can serve as a supplementary parameter for evaluating cervical sagittal balance and compensatory ability. The formula CL = 0.36×OI - 0.67×OT - 0.69×T1S provides the best predictions for physiological CL in the neutral position.