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M17.1 ICD-10-CM Code: Unilateral primary osteoarthritis of knee

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Billing Status: NO. This is a non-billable ICD-10-CM code: report a more specific billable code beneath it.

Coding at a Glance

Tabular directives
1 inclusion term · 1 Excludes2

Not billable · FY2027A non-billable heading in the tabular list: report a more specific code beneath it.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too; the Instructions section marks which is which.

Excludes2Not included here; may be reported together
  • osteoarthritis of spine (M47.-)
IncludesWhat this code covers
  • Primary osteoarthritis of knee NOS

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

CompareCheck ClaimView Related Codes

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for M17.1 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on M17.1 itself; “inherited from” names the category or block whose note applies here.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Primary osteoarthritis of knee NOS

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Source: inherited from M15-M19

Coder workflow for M17.1

MedCoder structured workflow — derived from this code’s own official record

Before you code M17.1

  1. M17.1 is not reportable as written. Select the more specific code beneath it that the documentation supports. Codes are reported to the highest level of specificity the classification provides (Guidelines I.B.2).

    ReviewM17.10, M17.11, M17.12

    See the relationships section · Guide: How to choose an ICD-10-CM code →

Choose the right path

  1. Does the documentation support one of the more specific codes beneath M17.1?
    Yes → Select that code and continue the checks below on its own page.
    No → M17.1 cannot be reported as written; query for the specificity its subcategory needs.

    ReviewM17.10, M17.11, M17.12

Consider M17.1. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Official instructions as workflow

  • Excludes2 — not part of M17.1(1 note)

    Coding workflow: The conditions named in this note are not included in M17.1. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareM47

    See the official tabular notes · Guidelines I.A.12.b

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse M17.1 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of M17.1 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • M17.9— Specificity relationship (Review)

    Overlapping diagnoses in the same category.

    Overlapping codes in the same category — the documentation decides which is the more specific fit.

    What moves you there: A record that documents no more than “Osteoarthritis of knee, unspecified” takes M17.9; specificity in the record moves it back here.

    Full comparison: M17.1 vs M17.9 →

  • M47— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of osteoarthritis of spine adds M47; it is not part of this code and both may be reported when both are documented.

    Full comparison: M17.1 vs M47 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Unilateral primary osteoarthritis of knee is a non-billable ICD-10-CM category code (M17.1). A more specific billable subcode must be selected for claims submission.

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Verify Before Coding

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name M17.1 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 3 Excludes1 notes: M12 — Other and unspecified arthropathy (via M17.-), M13 — Other arthritis (via M17.-), M15 — Polyosteoarthritis (via M17.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Related Codes

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Osteoarthritis”; these codes share that main term but sit in a different category of the Tabular List.

M15.9 — Polyosteoarthritis, unspecified (generalized), M16.0 — Bilateral primary osteoarthritis of hip (hip, bilateral), M16.1 — Unilateral primary osteoarthritis of hip (primary, hip), M16.2 — Bilateral osteoarthritis resulting from hip dysplasia (hip, bilateral, due to hip dysplasia), M16.3 — Unilateral osteoarthritis resulting from hip dysplasia (hip, due to hip dysplasia), M16.4 — Bilateral post-traumatic osteoarthritis of hip (hip, bilateral, post-traumatic), M16.5 — Unilateral post-traumatic osteoarthritis of hip (post-traumatic NEC, hip), M16.6 — Other bilateral secondary osteoarthritis of hip (secondary, hip, bilateral), M16.7 — Other unilateral secondary osteoarthritis of hip (secondary, hip), M16.9 — Osteoarthritis of hip, unspecified (hip), M18.0 — Bilateral primary osteoarthritis of first carpometacarpal joints (primary, hand joint, first carpometacarpal joint, bilateral), M18.1 — Unilateral primary osteoarthritis of first carpometacarpal joint (primary, hand joint, first carpometacarpal joint), M18.2 — Bilateral post-traumatic osteoarthritis of first carpometacarpal joints (post-traumatic NEC, hand joint, first carpometacarpal joint, bilateral), M18.3 — Unilateral post-traumatic osteoarthritis of first carpometacarpal joint (post-traumatic NEC, hand joint, first carpometacarpal joint), M18.4 — Other bilateral secondary osteoarthritis of first carpometacarpal joints (secondary, hand joint, first carpometacarpal joint, bilateral), M18.5 — Other unilateral secondary osteoarthritis of first carpometacarpal joint (secondary, hand joint, first carpometacarpal joint), M18.9 — Osteoarthritis of first carpometacarpal joint, unspecified (hand joint, first carpometacarpal joint), M19.01 — Primary osteoarthritis, shoulder (shoulder), M19.02 — Primary osteoarthritis, elbow (elbow), M19.03 — Primary osteoarthritis, wrist (wrist), +25 more

Contextual Map

Every relationship of M17.1 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run M17.1 with these 3 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

  • M12 — Other and unspecified arthropathy[Excludes1](via M17.-): “arthrosis (M15-M19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2027
  • M13 — Other arthritis[Excludes1](via M17.-): “arthrosis (M15-M19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2027
  • M15 — Polyosteoarthritis[Excludes1](via M17.-): “bilateral involvement of single joint (M16-M19)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2027

Nearest codes (13)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Relevant guides

Reference

Index terms and tables, published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

Common coding questions

MedCoder editorial

Can M17.1 be billed directly?

No. M17.1 (Unilateral primary osteoarthritis of knee) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder-derived relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder editorial explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 28, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "M17.1 — Unilateral primary osteoarthritis of knee." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/m17.1-unilateral-primary-osteoarthritis-of-knee

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Unilateral primary osteoarthritis of knee

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to M17.1 in its code family, with their registry titles.

View all codes in the M17 family