2026 ICD-10-CM Diagnosis Code M23.251Derangement of posterior horn of lateral meniscus due to old tear or injury, right knee

ICD-10-CM Codes›M00–M99›M20-M25›M23

ICD-10-CM M23.251
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M23.251 is a billable ICD-10-CM diagnosis code for derangement of posterior horn of lateral meniscus due to old tear or injury, 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified joint disorders.

Code Identity

ICD-10-CM Code
M23.251
Billable Status
Yes — Valid for Submission
Code Describes
Derangement of posterior horn of lateral meniscus due to old tear or injury, right knee
Short Description
Derang of post horn of lat mensc due to old tear/inj, r knee
Parent Code
M23.25
Derangement of posterior horn of lateral meniscus due to old tear or injury

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM20-M25Other joint disorders
CategoryM23Internal derangement of knee
This CodeM23.251Derangement of posterior horn of lateral meniscus due to old tear or injury, 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

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 M23.251 to ICD-9-CMHistory

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

ICD-9-CM
717.43 Derang post lat 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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M23.251Overview

Is M23.251 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report derangement of posterior horn of lateral meniscus due to old tear or injury, right knee on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M23.251 group to?

When derangement of posterior horn of lateral meniscus due to old tear or injury, 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 M23.251?

Under the General Equivalence Mappings, derangement of posterior horn of lateral meniscus due to old tear or injury, right knee converts to ICD-9-CM 717.43 (derang post lat meniscus). 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.