2027 ICD-10-CM Diagnosis Code M17.9Osteoarthritis of knee, unspecified

ICD-10-CM Codes›M00–M99›M15-M19›M17

ICD-10-CM M17.9
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

M17.9 is a billable ICD-10-CM diagnosis code for osteoarthritis of knee, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 553 through 554. Coders also document this condition as osteoarthritis of knee. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Osteoarthritis.

This medical diagnosis code is frequently used in Orthopedics medical specialties to designate conditions such osteoarthritis of the knee.

Code Identity

ICD-10-CM Code
M17.9
Billable Status
Yes — Valid for Submission
Code Describes
Osteoarthritis of knee, unspecified
Short Description
Osteoarthritis of knee, unspecified
Same as the full description in the CMS dataset.
Parent Code
M17
Osteoarthritis of knee

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM15-M19Osteoarthritis
CategoryM17Osteoarthritis of knee
This CodeM17.9Osteoarthritis of knee, unspecified

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Osteoarthritis of knee

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to M17.9: its own notes plus those printed at block M00-M25, block M15-M19, and Chapter 13. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From Block M00-M25 applies to 2,249 codes
  • Disorders affecting predominantly peripheral (limb) joints

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Block M15-M19 Osteoarthritis applies to 98 codes
  • osteoarthritis of spine (M47.-)
From Chapter 13 (M00-M99) Diseases of the musculoskeletal system and connective tissue applies to 6,687 codes
  • arthropathic psoriasis (L40.5-)
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • compartment syndrome (traumatic) (T79.A-)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Notes

General instructions on how these codes are used.

From Chapter 13 (M00-M99) Diseases of the musculoskeletal system and connective tissue applies to 6,687 codes
  • Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name M17.9, its category, or a range that includes it.

Excludes1 5

These codes carry an Excludes1 note naming M17.9: they are not reported together with it, unless the two conditions are unrelated.

  • M12 Other and unspecified arthropathy
    arthrosis (M15-M19) names M15-M19, which includes this code
  • M13 Other arthritis
    arthrosis (M15-M19) names M15-M19, which includes this code
  • M13 Other arthritis
    osteoarthritis (M15-M19) names M15-M19, which includes this code
  • M13.8 Other specified arthritis
    osteoarthritis (M15-M19) names M15-M19, which includes this code
  • M15 Polyosteoarthritis
    bilateral involvement of single joint (M16-M19) names M16-M19, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MUS006
Osteoarthritis
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Osteoarthritis, Knee

    noninflammatory degenerative disease of the knee joint consisting of three large categories: conditions that block normal synchronous movement, conditions that produce abnormal pathways of motion, and conditions that cause stress concentration resulting in changes to articular cartilage. (crenshaw, campbell's operative orthopaedics, 8th ed, p2019)

Patient EducationClinical

Osteoarthritis

Osteoarthritis, sometimes called OA, is a type of arthritis that only affects the joints, usually in the hands, knees, hips, neck, and lower back. It's the most common type of arthritis.

The full article covers:

  • What is osteoarthritis?
  • What are the symptoms of osteoarthritis?
  • What causes osteoarthritis?
  • Who is more likely to develop osteoarthritis?
  • How is osteoarthritis diagnosed?
  • What are the treatments for osteoarthritis?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert M17.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
715.36 Loc osteoarth NOS-l/leg
Approximate The match is approximate rather than exact.
ICD-9-CM
715.96 Osteoarthros NOS-l/leg
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About M17.9Overview

What is the ICD-10 code for osteoarthritis of knee, unspecified?

The ICD-10-CM code for osteoarthritis of knee, unspecified is M17.9 (sometimes written as M179). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is M17.9 (Osteoarthritis of knee) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report osteoarthritis of knee, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does M17.9 group to?

When osteoarthritis of knee, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 554, 553, with relative weights from 0.8328 to 1.2492 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M17.9?

Under the General Equivalence Mappings, osteoarthritis of knee, unspecified converts to ICD-9-CM 715.36 (loc osteoarth NOS-l/leg) and 715.96 (osteoarthros NOS-l/leg). The mapping is approximate, so confirm the match fits the documentation.