ICD-10-CM > S00-T88 > S10-S19 > S13 > S13.1 > S13.12 > S13.121 S13.121 Dislocation of C1/C2 cervical vertebrae Non-Billable/Non-Specific Codes S13.121A..., initial encounterS13.121D..., subsequent encounterS13.121S..., sequela