2026 ICD-10-CM Diagnosis Code M22.42Chondromalacia patellae, left knee

ICD-10-CM Codes›M00–M99›M20-M25›M22

ICD-10-CM M22.42
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M22.42 is a billable ICD-10-CM diagnosis code for chondromalacia patellae, left 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified joint disorders.

Code Identity

ICD-10-CM Code
M22.42
Billable Status
Yes — Valid for Submission
Code Describes
Chondromalacia patellae, left knee
Short Description
Chondromalacia patellae, left knee
Same as the full description in the CMS dataset.
Parent Code
M22.4
Chondromalacia patellae

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM20-M25Other joint disorders
CategoryM22Disorder of patella
This CodeM22.42Chondromalacia patellae, left knee

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Chondromalacia of bilateral patellas
  • Chondromalacia of joint of left knee
  • Chondromalacia of joint of right knee
  • Chondromalacia of left patella
  • Chondromalacia of patella
  • Chondromalacia of right patella
  • Degenerative disorder of articular cartilage of left knee
  • Degenerative disorder of articular cartilage of right knee

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

Clinical InformationClinical

  • Chondromalacia Patellae

    a degeneration of the articular cartilage of the patella, caused by a decrease in sulfated mucopolysaccharides in the ground substance. when accompanied by pain, it is sometimes considered part of or confused with patellofemoral pain syndrome.

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 M22.42 to ICD-9-CMHistory

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

ICD-9-CM
717.7 Chondromalacia patellae
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 M22.42Overview

Is M22.42 (Chondromalacia patellae) a billable code?

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

What MS-DRG does M22.42 group to?

When chondromalacia patellae, left 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 M22.42?

Under the General Equivalence Mappings, chondromalacia patellae, left knee converts to ICD-9-CM 717.7 (chondromalacia patellae). 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.