2026 ICD-10-CM Diagnosis Code M08.079Unspecified juvenile rheumatoid arthritis, unspecified ankle and foot
ICD-10-CM Codes›M00–M99›M05-M14›M08
- Billable — Valid for Submission
- Risk Adjusts — HCC 93
- Chronic Condition
M08.079 is a billable ICD-10-CM diagnosis code for unspecified juvenile rheumatoid arthritis, unspecified 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 545 through 547. Coders also document this condition as inflammation of interphalangeal joint of toe. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Juvenile arthritis.
For Medicare Advantage risk adjustment, M08.079 maps to CMS-HCC Category 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders) under the V28 model, adding a risk factor of about 0.617 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
M08.079 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Inflammation of interphalangeal joint of toe
- Rheumatoid arthritis - ankle and/or foot
- Rheumatoid arthritis of ankle
- Rheumatoid arthritis of first metatarsophalangeal joint
- Rheumatoid arthritis of foot
- Rheumatoid arthritis of interphalangeal joint of toe
- Rheumatoid arthritis of lesser metatarsophalangeal joint
- Rheumatoid arthritis of subtalar joint
- Rheumatoid arthritis of talonavicular joint
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Juvenile Arthritis
Juvenile arthritis (JA) is arthritis that happens in children. It causes joint inflammation (swelling), pain, stiffness, and loss of motion. Joints are places where two bones meet, such as your elbow or knee. It can affect any joint, but it is more common in the knees, hands, and feet.
The full article covers:
- What is juvenile arthritis?
- Who is more likely to get juvenile arthritis?
- What causes juvenile arthritis?
- What are the symptoms of juvenile arthritis?
- How is juvenile arthritis diagnosed?
- What are the treatments for juvenile arthritis?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert M08.079 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M08.079Overview
What is the ICD-10 code for unspecified juvenile rheumatoid arthritis, unspecified ankle and foot?
The ICD-10-CM code for unspecified juvenile rheumatoid arthritis, unspecified ankle and foot is M08.079 (sometimes written as M08079). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is M08.079 (Unspecified juvenile rheumatoid arthritis, ankle and foot) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report unspecified juvenile rheumatoid arthritis, unspecified ankle and foot on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does M08.079 group to?
When unspecified juvenile rheumatoid arthritis, unspecified ankle and foot is the principal diagnosis on an inpatient stay, it groups to MS-DRG 545, 546, 547, with relative weights from 0.8362 to 2.4817 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of M08.079?
Under the General Equivalence Mappings, unspecified juvenile rheumatoid arthritis, unspecified ankle and foot converts to ICD-9-CM 714.30 (juv rheum arthritis NOS). The mapping is approximate, so confirm the match fits the documentation.
What HCC is M08.079?
M08.079 (unspecified juvenile rheumatoid arthritis, unspecified ankle and foot) maps to CMS-HCC Category 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders), commonly written as HCC 93, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 40 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 83.
Does M08.079 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, M08.079 adds a risk adjustment factor of about 0.617 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.288 to 0.617 depending on the payment segment). HCC 93 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 93 category page.
