2026 ICD-10-CM Diagnosis Code M12.462Intermittent hydrarthrosis, left knee

ICD-10-CM Codes›M00–M99›M05-M14›M12

ICD-10-CM M12.462
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M12.462 is a billable ICD-10-CM diagnosis code for intermittent hydrarthrosis, left knee. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 553 through 554. Coders also document this condition as effusion of joint of bilateral knees. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified joint disorders.

Code Identity

ICD-10-CM Code
M12.462
Billable Status
Yes — Valid for Submission
Code Describes
Intermittent hydrarthrosis, left knee
Short Description
Intermittent hydrarthrosis, left knee
Same as the full description in the CMS dataset.
Parent Code
M12.46
Intermittent hydrarthrosis, knee

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM05-M14Inflammatory polyarthropathies
CategoryM12Other and unspecified arthropathy
This CodeM12.462Intermittent hydrarthrosis, left knee

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Effusion of joint of bilateral knees
  • Effusion of joint of left knee
  • Effusion of joint of right knee
  • Intermittent effusion of joint of bilateral knees
  • Intermittent hydrarthrosis of left knee
  • Intermittent hydrarthrosis of right knee
  • Knee joint effusion

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

Joint Disorders

Your joints are places where two or more bones come together. Your shoulders, elbows, hips, knees, and knuckles are all joints. Your spine has joints, too.

The full article covers:

  • What are joints?
  • What are joint disorders?
  • What diseases can affect the joints?
  • What types of joint disorders happen from sudden injuries?
  • What types of joint disorders happen from overuse?
  • How can I keep my joints healthy?

Read the full article at MedlinePlus

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

Convert M12.462 to ICD-9-CMHistory

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

ICD-9-CM
719.36 Palindrom rheum-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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M12.462Overview

Is M12.462 (Intermittent hydrarthrosis, knee) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report intermittent hydrarthrosis, left knee on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M12.462 group to?

When intermittent hydrarthrosis, left knee is the principal diagnosis on an inpatient stay, it groups to MS-DRG 553, 554, with relative weights from 0.8301 to 1.2963 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M12.462?

Under the General Equivalence Mappings, intermittent hydrarthrosis, left knee converts to ICD-9-CM 719.36 (palindrom rheum-l/leg). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.