2026 ICD-10-CM Diagnosis Code M21.6X1Other acquired deformities of right foot

ICD-10-CM Codes›M00–M99›M20-M25›M21

ICD-10-CM M21.6X1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M21.6X1 is a billable ICD-10-CM diagnosis code for other acquired deformities of right foot. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 564 through 566. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acquired foot deformities.

Code Identity

ICD-10-CM Code
M21.6X1
Billable Status
Yes — Valid for Submission
Code Describes
Other acquired deformities of right foot
Short Description
Other acquired deformities of right foot
Same as the full description in the CMS dataset.
Parent Code
M21.6X
Other acquired deformities of foot

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM20-M25Other joint disorders
CategoryM21Other acquired deformities of limbs
This CodeM21.6X1Other acquired deformities of right foot

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acquired abduction deformity of foot
  • Acquired calcaneovalgus deformity of bilateral feet
  • Acquired calcaneovalgus deformity of left foot
  • Acquired calcaneovalgus deformity of right foot
  • Acquired cavovarus deformity of bilateral feet
  • Acquired cavovarus deformity of foot
  • Acquired cavovarus deformity of left foot
  • Acquired cavovarus deformity of right foot
  • Acquired cavus deformity of left foot
  • Acquired cavus deformity of right foot
  • Acquired forefoot abductus
  • Acquired left metatarsus adductus
  • Acquired metatarsus adductus
  • Acquired metatarsus adductus of bilateral feet
  • Acquired right metatarsus adductus
  • Bilateral acquired calcaneovarus deformity of feet
  • Bilateral acquired cavus deformity of feet
  • Bilateral deformity of feet due to rheumatoid arthritis
  • Bilateral talipes calcaneovalgus
  • Calcaneovalgus deformity of foot
  • Cavovarus deformity of foot
  • Deformity of foot due to rheumatoid arthritis
  • Deformity of right foot co-occurrent and due to rheumatoid arthritis
  • Plantarflexion deformity of bilateral feet
  • Plantarflexion deformity of foot
  • Plantarflexion deformity of left foot
  • Plantarflexion deformity of right foot
  • Varus deformities of feet

Clinical ClassificationClinical

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

CCSR MUS021
Acquired foot deformities
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Foot Injuries and Disorders

Each of your feet has 26 bones, 33 joints, and more than 100 tendons, muscles, and ligaments. No wonder a lot of things can go wrong. Here are a few common problems:

Read the full article at MedlinePlus

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

Convert M21.6X1 to ICD-9-CMHistory

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

ICD-9-CM
736.79 Acq ankle-foot def NEC
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 M21.6X1Overview

Is M21.6X1 (Other acquired deformities of foot) a billable code?

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

What MS-DRG does M21.6X1 group to?

When other acquired deformities of right foot is the principal diagnosis on an inpatient stay, it groups to MS-DRG 564, 565, 566, with relative weights from 0.7493 to 1.5436 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M21.6X1?

Under the General Equivalence Mappings, other acquired deformities of right foot converts to ICD-9-CM 736.79 (acq ankle-foot def NEC). 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.