2027 ICD-10-CM Diagnosis Code M12.861Other specific arthropathies, not elsewhere classified, right knee

ICD-10-CM Codes›M00–M99›M05-M14›M12

ICD-10-CM M12.861
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

M12.861 is a billable ICD-10-CM diagnosis code for other specific arthropathies, not elsewhere classified, right knee. 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 arthropathy of right knee joint. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified joint disorders.

Code Identity

ICD-10-CM Code
M12.861
Billable Status
Yes — Valid for Submission
Code Describes
Other specific arthropathies, not elsewhere classified, right knee
Short Description
Oth specific arthropathies, NEC, right knee
Parent Code
M12.86
Other specific arthropathies, not elsewhere classified, knee

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM05-M14Inflammatory polyarthropathies
CategoryM12Other and unspecified arthropathy
This CodeM12.861Other specific arthropathies, not elsewhere classified, right knee

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Arthropathy of right knee joint
  • Bilateral arthropathy of knee joints
  • Hemophilic arthropathy of right knee

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to M12.861: its own notes plus those printed at M12, block M00-M25, 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

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From M12 Other and unspecified arthropathy applies to 169 codes

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 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.

Clinical ClassificationClinical

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

CCSR MUS007
Other specified joint disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Knee Injuries and Disorders

Your knee joint is made up of bone, cartilage, ligaments and fluid. Muscles and tendons help the knee joint move. When any of these structures is hurt or diseased, you have knee problems. Knee problems can cause pain and difficulty walking.

Read the full article at MedlinePlus

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

Convert M12.861 to ICD-9-CMHistory

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

ICD-9-CM
716.46 Trans arthropathy-l/leg
Approximate The match is approximate rather than exact.
ICD-9-CM
716.86 Arthropathy NEC-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 M12.861Overview

What is the ICD-10 code for other specific arthropathies, not elsewhere classified, right knee?

The ICD-10-CM code for other specific arthropathies, not elsewhere classified, right knee is M12.861 (sometimes written as M12861). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is M12.861 (Other specific arthropathies, not elsewhere classified, knee) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other specific arthropathies, not elsewhere classified, right knee on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does M12.861 group to?

When other specific arthropathies, not elsewhere classified, right knee 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.

Can M12.861 be reported with J38.7?

Not as a rule. The Excludes1 note at M12, which applies to M12.861, lists "cricoarytenoid arthropathy (J38.7)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

What is the ICD-9 equivalent of M12.861?

Under the General Equivalence Mappings, other specific arthropathies, not elsewhere classified, right knee converts to ICD-9-CM 716.46 (trans arthropathy-l/leg) and 716.86 (arthropathy NEC-l/leg). The mapping is approximate, so confirm the match fits the documentation.