M86.279 Subacute osteomyelitis, unspecified ankle and foot

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

Applies from M86 Osteomyelitis

Excludes1 (never code together)

• osteomyelitis due to:
• echinococcus (B67.2)
• gonococcus (A54.43)
• salmonella (A02.24)

Excludes2 (not included here)

• ostemyelitis of:
• orbit (H05.0-)
• petrous bone (H70.2-)
• vertebra (M46.2-)

Use additional code

• code (B95-B97) to identify infectious agent
• code to identify major osseous defect, if applicable (M89.7-)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 92 — Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis
• CMS-HCC V22: HCC 39 — Bone/Joint/Muscle Infections/Necrosis
• ESRD V24: HCC 39

MS-DRG index

Defines the logic of DRG(s) 539-541 in MDC 08.

Approximate ICD-9-CM (GEMs)

• 730.07 Acute osteomyelitis, 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 M86.279

Back-references to M86

• Code First: M89.7 Major osseous defect ("osteomyelitis (M86.-)")

Nearby codes

• M86.262 Subacute osteomyelitis, left tibia and fibula
• M86.269 Subacute osteomyelitis, unspecified tibia and fibula
• M86.27 Subacute osteomyelitis, ankle and foot
• M86.271 Subacute osteomyelitis, right ankle and foot
• M86.272 Subacute osteomyelitis, left ankle and foot
• M86.279 Subacute osteomyelitis, unspecified ankle and foot (this code)
• M86.28 Subacute osteomyelitis, other site
• M86.29 Subacute osteomyelitis, multiple sites
• M86.3 Chronic multifocal osteomyelitis
• M86.30 Chronic multifocal osteomyelitis, unspecified site
• M86.31 Chronic multifocal osteomyelitis, shoulder