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ICD-10-CM 2027

ICD-10 code for atlantoaxial dislocation

S13.121

Dislocation of C1/C2 cervical vertebrae

Header — needs a more specific code

From the official ICD-10-CM alphabetic index entry “Dislocation (articular) › atlantoaxial”. Page updated September 29, 2026.

About coding atlantoaxial dislocation

The ICD-10-CM code for atlantoaxial dislocation is S13.121 (Dislocation of C1/C2 cervical vertebrae).

Within S13.12 (subluxation and dislocation of C1/C2 cervical vertebrae), S13.121 is specifically for dislocation of C1/C2 cervical vertebrae. Related codes cover subluxation of C1/C2 cervical vertebrae (S13.120).

Codes in this range require a 7th character: A for initial encounter, D for subsequent encounter and S for sequela. Use placeholder "X" characters to fill any empty positions before the 7th character.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Common questions about atlantoaxial dislocation ICD-10 codes

What is the ICD-10 code for atlantoaxial dislocation?

S13.121 — Dislocation of C1/C2 cervical vertebrae (a header code; report a more specific subcode).

Is S13.121 billable?

No. S13.121 is a header code. Report one of its more specific subcodes instead.