ICD-10-CM 2027 diagnosis code

M17.1Unilateral primary osteoarthritis of knee

Not billable — use a more specific code

M17.1 is a header code, so it can't be reported by itself. Choose one of the 3 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About M17.1

M17.1 is the ICD-10-CM diagnosis code for unilateral primary osteoarthritis of knee. It belongs to category M17 (osteoarthritis of knee), block M15-M19 (osteoarthritis) and chapter 13 (diseases of the musculoskeletal system and connective tissue). It is a header code, so it can't be reported by itself; one of its 3 subcodes must be used instead.

Within M17 (osteoarthritis of knee), M17.1 is specifically for unilateral primary osteoarthritis of knee. Related codes cover bilateral primary osteoarthritis of knee (M17.0), bilateral post-traumatic osteoarthritis of knee (M17.2), unilateral post-traumatic osteoarthritis of knee (M17.3), other bilateral secondary osteoarthritis of knee (M17.4), other unilateral secondary osteoarthritis of knee (M17.5) and unspecified (M17.9).

To report this condition, pick the subcode that matches the documentation: M17.10 (knee), M17.11 (knee) and M17.12 (knee).

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

Specific codes under M17.1

Coding notes

Applicable toConditions and synonyms classified to this code

Primary osteoarthritis of knee NOS

Notes that apply from higher levels

Instructions written at a parent level also apply to M17.1.

Broader instructions also apply from M15-M19 Osteoarthritis and Chapter 13: Diseases of the musculoskeletal system and connective tissue.

Alphabetic index entries

4 entries

Terms in the official ICD-10-CM index that lead to M17.1.

Code history

2016
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2026
2027

FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
No changes since FY2016.

Common questions about M17.1

Is M17.1 billable?: No. M17.1 is a header code. Report one of its more specific subcodes instead.