M86.40 Chronic osteomyelitis with draining sinus, unspecified site

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) 456-458 in MDC 08.

Approximate ICD-9-CM (GEMs)

• 730.10 Chronic osteomyelitis, site unspecified (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 M86.40

Back-references to M86

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

Diagnosis Index entries for M86.40

• Osteomyelitis (general) (infective) (localized) (neonatal) (purulent) (septic) (staphylococcal) (streptococcal) (suppurative) (with periostitis) › chronic (or old) › with draining sinus

Nearby codes

• M86.372 Chronic multifocal osteomyelitis, left ankle and foot
• M86.379 Chronic multifocal osteomyelitis, unspecified ankle and foot
• M86.38 Chronic multifocal osteomyelitis, other site
• M86.39 Chronic multifocal osteomyelitis, multiple sites
• M86.4 Chronic osteomyelitis with draining sinus
• M86.40 Chronic osteomyelitis with draining sinus, unspecified site (this code)
• M86.41 Chronic osteomyelitis with draining sinus, shoulder
• M86.411 Chronic osteomyelitis with draining sinus, right shoulder
• M86.412 Chronic osteomyelitis with draining sinus, left shoulder
• M86.419 Chronic osteomyelitis with draining sinus, unspecified shoulder
• M86.42 Chronic osteomyelitis with draining sinus, humerus