2027 ICD-10-CM Diagnosis Code M20.22Hallux rigidus, left foot

ICD-10-CM Codes›M00–M99›M20-M25›M20

ICD-10-CM M20.22
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

M20.22 is a billable ICD-10-CM diagnosis code for hallux rigidus, left foot. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 564 through 566. Coders also document this condition as acquired hallux rigidus. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acquired foot deformities.

Code Identity

ICD-10-CM Code
M20.22
Billable Status
Yes — Valid for Submission
Code Describes
Hallux rigidus, left foot
Short Description
Hallux rigidus, left foot
Same as the full description in the CMS dataset.
Parent Code
M20.2
Hallux rigidus

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM20-M25Other joint disorders
CategoryM20Acquired deformities of fingers and toes
This CodeM20.22Hallux rigidus, left foot

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acquired hallux rigidus
  • Acquired left hallux rigidus
  • Acquired right hallux rigidus
  • Bilateral acquired hallux limitus of great toes
  • Bilateral acquired hallux rigidus of bilateral feet

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to M20.22: its own notes plus those printed at M20, 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 M20 Acquired deformities of fingers and toes applies to 33 codes
  • acquired absence of fingers and toes (Z89.-)
  • congenital absence of fingers and toes (Q71.3-, Q72.3-)
  • congenital deformities and malformations of fingers and toes (Q66.-, Q68-Q70, Q74.-)

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 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 M20.22, its category, or a range that includes it.

Excludes2 3

These codes carry an Excludes2 note naming M20.22: its condition is not part of those codes, and both may be reported when the patient has both.

  • M19 Other and unspecified osteoarthritis
    hallux rigidus (M20.2) names M20.2, which includes this code
  • M21 Other acquired deformities of limbs
    acquired deformities of fingers or toes (M20.-) names M20.-, which includes this code
  • M21.6 Other acquired deformities of foot
    deformities of toe (acquired) (M20.1-M20.6-) names M20.1-M20.6, which includes this code

Clinical ClassificationClinical

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

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

Clinical InformationClinical

  • Hallux Rigidus

    a condition caused by degenerative arthritis (see osteoarthritis) of the metatarsophalangeal joint of the great toe and characterized by pain and limited dorsiflexion, but relatively unrestricted plantar flexion.

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 M20.22 to ICD-9-CMHistory

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

ICD-9-CM
735.2 Hallux rigidus
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 M20.22Overview

What is the ICD-10 code for hallux rigidus, left foot?

The ICD-10-CM code for hallux rigidus, left foot is M20.22 (sometimes written as M2022). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is M20.22 (Hallux rigidus) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report hallux rigidus, left foot on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does M20.22 group to?

When hallux rigidus, left foot is the principal diagnosis on an inpatient stay, it groups to MS-DRG 564, 566, 565, with relative weights from 0.7374 to 1.4909 depending on complications. Higher weights mean higher Medicare reimbursement.

Can M20.22 be reported with a code from Z89?

Not as a rule. The Excludes1 note at M20, which applies to M20.22, lists "acquired absence of fingers and toes (Z89.-)". 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 M20.22?

Under the General Equivalence Mappings, hallux rigidus, left foot converts to ICD-9-CM 735.2 (hallux rigidus). The mapping is approximate, so confirm the match fits the documentation.