M45 – Ankylosing spondylitis

ICD-10-CM 2027 diagnosis code · Spondylopathies

Non-billable header

ICD-10-CM code M45

Code: M45 (claims format: M45)
Description: Ankylosing spondylitis
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 13. Diseases of the musculoskeletal system and connective tissue (M00-M99)
Block: M45-M49 Spondylopathies

Billable codes under M45

M45 is a header code and cannot be used on claims. Choose the most specific code:

M45.0 – Ankylosing spondylitis of multiple sites in spineBillable
M45.1 – Ankylosing spondylitis of occipito-atlanto-axial regionBillable
M45.2 – Ankylosing spondylitis of cervical regionBillable
M45.3 – Ankylosing spondylitis of cervicothoracic regionBillable
M45.4 – Ankylosing spondylitis of thoracic regionBillable
M45.5 – Ankylosing spondylitis of thoracolumbar regionBillable
M45.6 – Ankylosing spondylitis lumbar regionBillable
M45.7 – Ankylosing spondylitis of lumbosacral regionBillable
M45.8 – Ankylosing spondylitis sacral and sacrococcygeal regionBillable
M45.9 – Ankylosing spondylitis of unspecified sites in spineBillable
M45.A – Non-radiographic axial spondyloarthritisHeader (more codes below)

Notes for M45

Applicable to:

Rheumatoid arthritis of spine

Excludes1 (not coded here):

arthropathy in Reiter's disease (M02.3-)
juvenile (ankylosing) spondylitis (M08.1)

Excludes2 (not included here):

Behçet's disease (M35.2)

Frequently asked questions

What is ICD-10 code M45?

M45 is the ICD-10-CM code for ankylosing spondylitis, in the block M45-M49 (Spondylopathies).

Is M45 a billable code?

No. M45 is a header code with more specific child codes; report one of the billable codes listed above.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.