2026 ICD-10-CM Diagnosis Code M20.099Other deformity of finger(s), unspecified finger(s)

ICD-10-CM Codes›M00–M99›M20-M25›M20

ICD-10-CM M20.099
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M20.099 is a billable ICD-10-CM diagnosis code for other deformity of finger(s), unspecified finger(s). 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 deformities (excluding foot).

Code Identity

ICD-10-CM Code
M20.099
Billable Status
Yes — Valid for Submission
Code Describes
Other deformity of finger(s), unspecified finger(s)
Short Description
Other deformity of finger(s), unspecified finger(s)
Same as the full description in the CMS dataset.
Parent Code
M20.09
Other deformity of finger(s)

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM20-M25Other joint disorders
CategoryM20Acquired deformities of fingers and toes
This CodeM20.099Other deformity of finger(s), unspecified finger(s)

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Abduction deformity of finger
  • Abnormal curvature of distal phalanx of hand
  • Abnormal curvature of distal phalanx of index finger
  • Abnormal curvature of distal phalanx of little finger
  • Abnormal curvature of distal phalanx of middle finger
  • Abnormal curvature of distal phalanx of ring finger
  • Abnormal curvature of distal phalanx of thumb
  • Abnormal curvature of middle phalanx of finger
  • Abnormal curvature of middle phalanx of index finger
  • Abnormal curvature of middle phalanx of little finger
  • Abnormal curvature of middle phalanx of middle finger
  • Abnormal curvature of middle phalanx of ring finger
  • Abnormal curvature of phalanx of hand
  • Abnormal curvature of phalanx of index finger
  • Abnormal curvature of phalanx of little finger
  • Abnormal curvature of phalanx of middle finger
  • Abnormal curvature of phalanx of ring finger
  • Abnormal curvature of phalanx of thumb
  • Abnormal curvature of proximal phalanx of index finger
  • Abnormal curvature of proximal phalanx of little finger
  • Abnormal curvature of proximal phalanx of middle finger
  • Abnormal curvature of proximal phalanx of ring finger
  • Abnormal curvature of proximal phalanx of thumb
  • Acquired deformity of the thumb
  • Acquired fixed flexion deformity of joint of upper limb
  • Acquired fixed flexion deformity of thumb
  • Adduction deformity of finger
  • Deviation of finger
  • Dropped finger
  • Extension deformity of finger
  • Fixed extension deformity of the thumb
  • Fixed flexion deformity of the thumb
  • Overriding fingers
  • Rotational deformity of finger
  • Rotational deformity of thumb
  • Short finger
  • Spindling of finger
  • Tapering fingers
  • Thumb joint deformity
  • Ulnar deviation of hand
  • Ulnar deviation of the thumb
  • Ulnar drift
  • Z deformity of thumb

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

Finger Injuries and Disorders

You use your fingers and thumbs to do everything from grasping objects to playing musical instruments to typing. When there is something wrong with them, it can make life difficult. Common problems include:

Read the full article at MedlinePlus

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

Convert M20.099 to ICD-9-CMHistory

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

ICD-9-CM
736.29 Acq finger deformity 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 M20.099Overview

Is M20.099 (Other deformity of finger(s)) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other deformity of finger(s), unspecified finger(s) on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M20.099 group to?

When other deformity of finger(s), unspecified finger(s) 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 M20.099?

Under the General Equivalence Mappings, other deformity of finger(s), unspecified finger(s) converts to ICD-9-CM 736.29 (acq finger deformity 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.