S13.120 ICD-10-CM Code: Subluxation of C1/C2 cervical vertebrae

S13.120 is the ICD-10-CM diagnosis code for subluxation of c1/c2 cervical vertebrae. S13.120 sits in the ICD-10-CM chapter for injury, poisoning and certain other consequences of external causes (s00-t88), within the section covering injuries to the neck (s10-s19).

Header codes like S13.120 cannot be reported on claims directly, they organize child codes that share clinical context but the actual diagnosis must be coded to the highest level of specificity supported by the documentation. Coders should look at S13.120's child codes and select the one that matches the patient's documented presentation, since payers reject header codes submitted as the primary diagnosis. For risk adjustment workflows, header codes never contribute to a Medicare Advantage member's RAF score on their own; only billable child codes that happen to map to a payment HCC affect risk-adjusted plan payments.