M02.379 Reiter's disease, unspecified ankle and foot

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applies from M02 Postinfective and reactive arthropathies

Excludes1 (never code together)

• Behçet's disease (M35.2)
• direct infections of joint in infectious and parasitic diseases classified elsewhere (M01.-)
• postmeningococcal arthritis (A39.84)
• mumps arthritis (B26.85)
• rubella arthritis (B06.82)
• syphilis arthritis (late) (A52.77)
• rheumatic fever (I00)
• tabetic arthropathy [Charcôt's] (A52.16)

Code first

• underlying disease, such as:
• congenital syphilis [Clutton's joints] (A50.5)
• enteritis due to Yersinia enterocolitica (A04.6)
• infective endocarditis (I33.0)
• viral hepatitis (B15-B19)

Applies from M02.3 Reiter's disease

Applicable to

• Reactive arthritis

Applies from M02.37 Reiter's disease, ankle and foot

Applicable to

• Reiter's disease, tarsus, metatarsus and phalanges

Risk adjustment (HCC)

• CMS-HCC V28: HCC 94 — Systemic Lupus Erythematosus and Other Specified Systemic Connective Tissue Disorders
• CMS-HCC V22: HCC 40 — Rheumatoid Arthritis and Inflammatory Connective Tissue Disease
• RxHCC V08: HCC 83 — Rheumatoid Arthritis and Other Inflammatory Polyarthropathy
• ESRD V24: HCC 40

MS-DRG index

Defines the logic of DRG(s) 545-547 in MDC 08.

Approximate ICD-9-CM (GEMs)

• 099.3 Reiter's disease (approximate)
• 711.17 Arthropathy associated with Reiter's disease and nonspecific urethritis, ankle and foot (approximate)

Medicare Code Edits (MCE v43.1 (April 2026))

• Unspecified code (laterality): Unspecified codes for which a more specific code identifying laterality (right, left, bilateral) exists within the same code family.

Code annotations containing back-references to M02.379

Back-references to M02.3

• Type 1 Excludes: A74 Other diseases caused by chlamydiae ("Reiter's disease (M02.3-)")
• Code First: L86 Keratoderma in diseases classified elsewhere ("Reiter's disease (M02.3-)")
• Type 1 Excludes: M01 Direct infections of joint in infectious and parasitic diseases classified elsewhere ("reactive arthritis (M02.3)")
• Type 1 Excludes: M45 Ankylosing spondylitis ("arthropathy in Reiter's disease (M02.3-)")
• Type 2 Excludes: N34 Urethritis and urethral syndrome ("Reiter's disease (M02.3-)")

Back-references to M02

• Type 1 Excludes: M01 Direct infections of joint in infectious and parasitic diseases classified elsewhere ("postinfective arthropathy (M02.-)")

Nearby codes

• M02.362 Reiter's disease, left knee
• M02.369 Reiter's disease, unspecified knee
• M02.37 Reiter's disease, ankle and foot
• M02.371 Reiter's disease, right ankle and foot
• M02.372 Reiter's disease, left ankle and foot
• M02.379 Reiter's disease, unspecified ankle and foot (this code)
• M02.38 Reiter's disease, vertebrae
• M02.39 Reiter's disease, multiple sites
• M02.8 Other reactive arthropathies
• M02.80 Other reactive arthropathies, unspecified site
• M02.81 Other reactive arthropathies, shoulder