2027 ICD-10-CM Diagnosis Code M23.012Cystic meniscus, anterior horn of medial meniscus, left knee

ICD-10-CM Codes›M00–M99›M20-M25›M23

ICD-10-CM M23.012
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

M23.012 is a billable ICD-10-CM diagnosis code for cystic meniscus, anterior horn of medial meniscus, left 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified joint disorders.

Code Identity

ICD-10-CM Code
M23.012
Billable Status
Yes — Valid for Submission
Code Describes
Cystic meniscus, anterior horn of medial meniscus, left knee
Short Description
Cystic meniscus, anterior horn of medial meniscus, left knee
Same as the full description in the CMS dataset.
Parent Code
M23.01
Cystic meniscus, anterior horn of medial meniscus

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM20-M25Other joint disorders
CategoryM23Internal derangement of knee
This CodeM23.012Cystic meniscus, anterior horn of medial meniscus, left knee

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral cyst of meniscus of knees
  • Bilateral medial meniscus cysts
  • Cyst of anterior horn of left medial meniscus
  • Cyst of anterior horn of medial meniscus of bilateral knees
  • Cyst of anterior horn of medial meniscus of knee
  • Cyst of anterior horn of right medial meniscus
  • Cyst of medial meniscus of left knee
  • Cyst of medial meniscus of right knee
  • Cyst of meniscus of left knee
  • Cyst of meniscus of right knee
  • Mass of bilateral knee joints

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to M23.012: its own notes plus those printed at M23, 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

Excludes1

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

From M23 Internal derangement of knee applies to 111 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 M23 Internal derangement of knee applies to 111 codes
  • current injury - see injury of knee and lower leg (S80-S89)
  • recurrent dislocation or subluxation of joints (M24.4)
  • recurrent dislocation or subluxation of patella (M22.0-M22.1)
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 M23.012, its category, or a range that includes it.

Excludes2 2

These codes carry an Excludes2 note naming M23.012: its condition is not part of those codes, and both may be reported when the patient has both.

  • M24.1 Other articular cartilage disorders
    internal derangement of knee (M23.-) names M23.-, which includes this code
  • S83 Dislocation and sprain of joints and ligaments of knee
    internal derangement of knee (M23.-) names M23.-, 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

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 M23.012 to ICD-9-CMHistory

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

ICD-9-CM
717.1 Derang ant med meniscus
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 M23.012Overview

What is the ICD-10 code for cystic meniscus, anterior horn of medial meniscus, left knee?

The ICD-10-CM code for cystic meniscus, anterior horn of medial meniscus, left knee is M23.012 (sometimes written as M23012). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is M23.012 (Cystic meniscus, anterior horn of medial meniscus) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report cystic meniscus, anterior horn of medial meniscus, left knee on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does M23.012 group to?

When cystic meniscus, anterior horn of medial meniscus, left 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.

Can M23.012 be reported with M24.66?

Not as a rule. The Excludes1 note at M23, which applies to M23.012, lists "ankylosis (M24.66)". 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 M23.012?

Under the General Equivalence Mappings, cystic meniscus, anterior horn of medial meniscus, left knee converts to ICD-9-CM 717.1 (derang ant med meniscus). The mapping is approximate, so confirm the match fits the documentation.