2027 ICD-10-CM Diagnosis Code M22.40Chondromalacia patellae, unspecified knee

ICD-10-CM Codes›M00–M99›M20-M25›M22

ICD-10-CM M22.40
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

M22.40 is a billable ICD-10-CM diagnosis code for chondromalacia patellae, unspecified knee. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 562 through 563. Coders also document this condition as chondromalacia of patella. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified joint disorders.

Code Identity

ICD-10-CM Code
M22.40
Billable Status
Yes — Valid for Submission
Code Describes
Chondromalacia patellae, unspecified knee
Short Description
Chondromalacia patellae, unspecified 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 CodeM22.40Chondromalacia patellae, unspecified knee

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Chondromalacia of patella
  • Familial chondromalacia of patella

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to M22.40: its own notes plus those printed at M22, block M00-M25, block M20-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

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 M22 Disorder of patella applies to 21 codes
  • traumatic dislocation of patella (S83.0-)
From Block M20-M25 Other joint disorders applies to 719 codes
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 M22.40, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming M22.40: they are not reported together with it, unless the two conditions are unrelated.

  • M94.2 Chondromalacia
    chondromalacia patellae (M22.4) names M22.4, which includes this code

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 M22.40 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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About M22.40Overview

What is the ICD-10 code for chondromalacia patellae, unspecified knee?

The ICD-10-CM code for chondromalacia patellae, unspecified knee is M22.40 (sometimes written as M2240). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is M22.40 (Chondromalacia patellae) a billable code?

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

What MS-DRG does M22.40 group to?

When chondromalacia patellae, unspecified knee is the principal diagnosis on an inpatient stay, it groups to MS-DRG 563, 562, with relative weights from 0.8982 to 1.3981 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M22.40?

Under the General Equivalence Mappings, chondromalacia patellae, unspecified knee converts to ICD-9-CM 717.7 (chondromalacia patellae). The mapping is approximate, so confirm the match fits the documentation.