2026 ICD-10-CM Diagnosis Code M65.871Other synovitis and tenosynovitis, right ankle and foot

ICD-10-CM Codes›M00–M99›M65-M67›M65

ICD-10-CM M65.871
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M65.871 is a billable ICD-10-CM diagnosis code for other synovitis and tenosynovitis, right ankle and foot. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 557 through 558. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Tendon and synovial disorders.

Code Identity

ICD-10-CM Code
M65.871
Billable Status
Yes — Valid for Submission
Code Describes
Other synovitis and tenosynovitis, right ankle and foot
Short Description
Other synovitis and tenosynovitis, right ankle and foot
Same as the full description in the CMS dataset.
Parent Code
M65.87
Other synovitis and tenosynovitis, ankle and foot

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM65-M67Disorders of synovium and tendon
CategoryM65Synovitis and tenosynovitis
This CodeM65.871Other synovitis and tenosynovitis, right ankle and foot

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Bilateral synovitis of joint of ankles
  • Bilateral synovitis of joint of feet
  • Bilateral tenosynovitis of ankles
  • Bilateral tenosynovitis of feet
  • Capsulitis of left ankle
  • Capsulitis of right ankle
  • Chronic synovitis of bilateral ankle joints due to hemarthrosis
  • Chronic synovitis of left ankle joint due to hemarthrosis
  • Chronic synovitis of right ankle joint due to hemarthrosis
  • Synovitis of ankle joint
  • Synovitis of joint of foot
  • Synovitis of joint of left foot
  • Synovitis of joint of right foot
  • Synovitis of left ankle joint
  • Synovitis of right ankle joint
  • Tenosynovitis of ankle
  • Tenosynovitis of foot
  • Tenosynovitis of left ankle
  • Tenosynovitis of left foot
  • Tenosynovitis of right ankle
  • Tenosynovitis of right foot

Clinical ClassificationClinical

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

CCSR MUS009
Tendon and synovial disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Joint Disorders

Your joints are places where two or more bones come together. Your shoulders, elbows, hips, knees, and knuckles are all joints. Your spine has joints, too.

The full article covers:

  • What are joints?
  • What are joint disorders?
  • What diseases can affect the joints?
  • What types of joint disorders happen from sudden injuries?
  • What types of joint disorders happen from overuse?
  • How can I keep my joints healthy?

Read the full article at MedlinePlus

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

Convert M65.871 to ICD-9-CMHistory

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

ICD-9-CM
727.06 Tenosynovitis foot/ankle
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 M65.871Overview

Is M65.871 (Other synovitis and tenosynovitis, ankle and foot) a billable code?

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

What MS-DRG does M65.871 group to?

When other synovitis and tenosynovitis, right ankle and foot is the principal diagnosis on an inpatient stay, it groups to MS-DRG 557, 558, with relative weights from 0.8932 to 1.4869 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M65.871?

Under the General Equivalence Mappings, other synovitis and tenosynovitis, right ankle and foot converts to ICD-9-CM 727.06 (tenosynovitis foot/ankle). 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.