M45.9 — Ankylosing spondylitis of unspecified sites in spine
M45.9 is a billable, specific ICD-10-CM code for ankylosing spondylitis of unspecified sites in spine. It is valid for submission on a claim.
Risk adjustment
M45.9 risk-adjusts. Under the CMS-HCC V28 model it maps to this category:
- HCC 93 Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders0.617 RAF
Coefficient shown for the Community Non-dual Aged segment. A higher HCC in the same hierarchy will suppress this one, so capturing it does not always add score.
Medicare coverage
M45.9 is named in 12 Medicare coverage policies — 6 listing it as supporting medical necessity, and 6 listing it as NOT covered. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A58865Billing and Coding: Amniotic and Placental-Derived Product Injections and/or Applications for Musculoskeletal Indications, Non-Woundnot covered
- A58893Billing and Coding: Amniotic and Placental-Derived Product Injections and/or Applications for Musculoskeletal Indications, Non-Woundnot covered
- A59374Billing and Coding: Amniotic and Placental-Derived Product Injections and/or Applications for Musculoskeletal Indications, Non-Woundnot covered
- A59434Billing and Coding: Amniotic and Placental-Derived Product Injections and/or Applications for Musculoskeletal Indications, Non-Woundnot covered
How M45.9 is indexed
Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to M45.9.
- Spondylitis›ankylosing(chronic)
- Iridocyclitis›in›ankylosing spondylitis
- Spondylitis›ankylosing›with lung involvement
Related codes at this level
Codes that share M45. If M45.9 is not quite right, the correct code is usually one of these.
- M45.0Ankylosing spondylitis of multiple sites in spine
- M45.1Ankylosing spondylitis of occipito-atlanto-axial region
- M45.2Ankylosing spondylitis of cervical region
- M45.3Ankylosing spondylitis of cervicothoracic region
- M45.4Ankylosing spondylitis of thoracic region
- M45.5Ankylosing spondylitis of thoracolumbar region
- M45.6Ankylosing spondylitis lumbar region
- M45.7Ankylosing spondylitis of lumbosacral region
- M45.8Ankylosing spondylitis sacral and sacrococcygeal region
- M45.ANon-radiographic axial spondyloarthritis
Questions about M45.9
- Is M45.9 a billable ICD-10-CM code?
- Yes. M45.9 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does M45.9 sit in the tabular list?
- Diseases of the musculoskeletal system and connective tissue (M00-M99), in the block Spondylopathies (M45-M49).