Ankylosing spondylitis (M45) ICD-10-CM
The M45 code range covers ankylosing spondylitis with 22 ICD-10-CM diagnosis codes. 20 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Inclusion Terms
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
- Rheumatoid arthritis of spine
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Type 2 Excludes
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
- Behçet's disease M35.2
Codes in the M45 Range 22 codes · 20 billable
- M45 Ankylosing spondylitisNon-billable
- M45.0 Ankylosing spondylitis of multiple sites in spine
- M45.1 Ankylosing spondylitis of occipito-atlanto-axial region
- M45.2 Ankylosing spondylitis of cervical region
- M45.3 Ankylosing spondylitis of cervicothoracic region
- M45.4 Ankylosing spondylitis of thoracic region
- M45.5 Ankylosing spondylitis of thoracolumbar region
- M45.6 Ankylosing spondylitis lumbar region
- M45.7 Ankylosing spondylitis of lumbosacral region
- M45.8 Ankylosing spondylitis sacral and sacrococcygeal region
- M45.9 Ankylosing spondylitis of unspecified sites in spine
- M45.A Non-radiographic axial spondyloarthritisNon-billable
- M45.A0 Non-radiographic axial spondyloarthritis of unspecified sites in spine
- M45.A1 Non-radiographic axial spondyloarthritis of occipito-atlanto-axial region
- M45.A2 Non-radiographic axial spondyloarthritis of cervical region
- M45.A3 Non-radiographic axial spondyloarthritis of cervicothoracic region
- M45.A4 Non-radiographic axial spondyloarthritis of thoracic region
- M45.A5 Non-radiographic axial spondyloarthritis of thoracolumbar region
- M45.A6 Non-radiographic axial spondyloarthritis of lumbar region
- M45.A7 Non-radiographic axial spondyloarthritis of lumbosacral region
- M45.A8 Non-radiographic axial spondyloarthritis of sacral and sacrococcygeal region
- M45.AB Non-radiographic axial spondyloarthritis of multiple sites in spine
About the M45 Code Range
ICD-10 code M45 covers ankylosing spondylitis, a chronic inflammatory condition affecting the spine. These codes specify which parts of the spine are involved, from multiple spinal sites to precise regions like cervical, thoracic, lumbar, and sacral. There are also codes for non-radiographic axial spondyloarthritis, a related condition without visible spine changes on X-rays.
The ICD-10 code for ankylosing spondylitis (M45) helps identify the extent and location of inflammation along the spine. Subcodes such as M45.2 correspond to ankylosing spondylitis of the cervical region, which may be called rheumatoid arthritis of cervical spine or cervical arthritis by some clinicians. Codes like M45.4 refer to thoracic spinal involvement, sometimes described as chest deformity due to ankylosing spondylitis. The code M45.9 accounts for unspecified spinal sites and covers cases with additional organ involvement or multisystem symptoms. Additionally, the M45.A series covers non-radiographic axial spondyloarthritis, a related condition where standard imaging does not show spine damage but symptoms resemble ankylosing spondylitis. These distinctions support accurate diagnosis, treatment planning, and medical billing focused on specific spine areas affected by inflammatory spondyloarthropathies.
Questions About This Page
How many billable codes are in the M45 range?
Of the 22 codes in this range, 20 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the M45 range classify?
The range classifies ankylosing spondylitis. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
