2026 ICD-10-CM Diagnosis Code M21.331Wrist drop, right wrist

ICD-10-CM Codes›M00–M99›M20-M25›M21

ICD-10-CM M21.331
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M21.331 is a billable ICD-10-CM diagnosis code for wrist drop, right wrist. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). Coders also document this condition as bilateral wrist drop. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acquired deformities (excluding foot).

Code Identity

ICD-10-CM Code
M21.331
Billable Status
Yes — Valid for Submission
Code Describes
Wrist drop, right wrist
Short Description
Wrist drop, right wrist
Same as the full description in the CMS dataset.
Parent Code
M21.33
Wrist drop (acquired)

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM20-M25Other joint disorders
CategoryM21Other acquired deformities of limbs
This CodeM21.331Wrist drop, right wrist

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral wrist drop
  • Left wrist drop
  • Right wrist drop
  • Wristdrop

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MUS023
Acquired deformities (excluding foot)
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Wrist Injuries and Disorders

Your wrist connects your hand to your forearm. It is not one big joint; it has several small joints. This makes it flexible and allows you to move your hand in different ways. The wrist has two big forearm bones and eight small bones known as carpals. It also has tendons and ligaments, which are connective tissues.

The full article covers:

  • What are the types of wrist injuries and disorders?
  • Who is at risk for wrist injuries and disorders?
  • What are the symptoms of wrist injuries and disorders?
  • How are wrist injuries and disorders diagnosed?
  • What are the treatments for wrist injuries and disorders?
  • Can wrist injuries and disorders be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert M21.331 to ICD-9-CMHistory

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

ICD-9-CM
736.05 Wrist drop
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 M21.331Overview

Is M21.331 (Wrist drop (acquired)) a billable code?

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

What is the ICD-9 equivalent of M21.331?

Under the General Equivalence Mappings, wrist drop, right wrist converts to ICD-9-CM 736.05 (wrist drop). 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.