2026 ICD-10-CM Diagnosis Code M21.059Valgus deformity, not elsewhere classified, unspecified hip

ICD-10-CM Codes›M00–M99›M20-M25›M21

ICD-10-CM M21.059
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M21.059 is a billable ICD-10-CM diagnosis code for valgus deformity, not elsewhere classified, unspecified hip. 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. Coders also document this condition as coxa valga. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acquired deformities (excluding foot).

Code Identity

ICD-10-CM Code
M21.059
Billable Status
Yes — Valid for Submission
Code Describes
Valgus deformity, not elsewhere classified, unspecified hip
Short Description
Valgus deformity, not elsewhere classified, unspecified hip
Same as the full description in the CMS dataset.
Parent Code
M21.05
Valgus deformity, not elsewhere classified, hip

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM20-M25Other joint disorders
CategoryM21Other acquired deformities of limbs
This CodeM21.059Valgus deformity, not elsewhere classified, unspecified hip

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Coxa valga

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

Clinical InformationClinical

  • Coxa Valga

    hip deformity in which the angle between the femoral neck and its shaft is increased. it may be congenital, acquired, or developmental.

Patient EducationClinical

Hip Injuries and Disorders

Your hip is the joint where your femur (thigh bone) meets your pelvis (hip bone). There are two main parts: a ball at the end of the femur, which fits in a socket in the pelvis. Your hip is known as a ball-and-socket joint. This is because you have a ball at the end of your femur, and it fits into a socket in your pelvis.

Read the full article at MedlinePlus

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

Convert M21.059 to ICD-9-CMHistory

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

ICD-9-CM
736.31 Coxa valga
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 M21.059Overview

Is M21.059 (Valgus deformity, not elsewhere classified, hip) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report valgus deformity, not elsewhere classified, unspecified hip on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M21.059 group to?

When valgus deformity, not elsewhere classified, unspecified hip 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 M21.059?

Under the General Equivalence Mappings, valgus deformity, not elsewhere classified, unspecified hip converts to ICD-9-CM 736.31 (coxa valga). 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.