2026 ICD-10-CM Diagnosis Code M22.91Unspecified disorder of patella, right knee

ICD-10-CM Codes›M00–M99›M20-M25›M22

ICD-10-CM M22.91
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M22.91 is a billable ICD-10-CM diagnosis code for unspecified disorder of patella, right knee. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 562 through 563. Coders also document this condition as bilateral disorder of patella. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified joint disorders.

Code Identity

ICD-10-CM Code
M22.91
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified disorder of patella, right knee
Short Description
Unspecified disorder of patella, right knee
Same as the full description in the CMS dataset.
Parent Code
M22.9
Unspecified disorder of patella

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM20-M25Other joint disorders
CategoryM22Disorder of patella
This CodeM22.91Unspecified disorder of patella, right knee

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral disorder of patella
  • Disorder of left patella
  • Disorder of right patella

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 M22.91 to ICD-9-CMHistory

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

ICD-9-CM
717.9 Int derangement knee NOS
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 M22.91Overview

Is M22.91 (Unspecified disorder of patella) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report unspecified disorder of patella, right knee on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M22.91 group to?

When unspecified disorder of patella, right knee is the principal diagnosis on an inpatient stay, it groups to MS-DRG 562, 563, with relative weights from 0.8955 to 1.4248 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M22.91?

Under the General Equivalence Mappings, unspecified disorder of patella, right knee converts to ICD-9-CM 717.9 (int derangement knee NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.