What is the ICD-10 code for osteomyelitis?

The ICD-10-CM code for osteomyelitis is M86.9 when documented without further specification. More specific documentation changes the code — see the scenario table.

Yes — M86.9 is a billable ICD-10-CM code, but payers expect the most specific code the documentation supports.

ICD-10 Code for osteomyelitis

The ICD-10-CM code for osteomyelitis is M86.9 when documented without further specification. HCC Osteomyelitis, unspecified codes to M86.9. Category M86 classifies bone infection by acuity (acute hematogenous, subacute, chronic), by cause, and by site with laterality. M86.9 applies only when neither the type nor the site is documented.

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Symptom code vs. confirmed diagnosis

Osteomyelitis is a provider-established diagnosis of bone infection, not a symptom. Assign M86.- when osteomyelitis is documented, selecting the acuity (acute, subacute, chronic) and the affected bone with laterality when the record specifies them.

Which Code Should You Use?

M86.9 ✓ Billable — Osteomyelitis, unspecified

Osteomyelitis, unspecified — type and site not documented.

M86.00 ✓ Billable — Acute hematogenous osteomyelitis, unspecified site

Acute hematogenous osteomyelitis, unspecified site.

M86.011 ✓ Billable — Acute hematogenous osteomyelitis, right shoulder

Acute hematogenous osteomyelitis, right shoulder.

M86.012 ✓ Billable — Acute hematogenous osteomyelitis, left shoulder

Acute hematogenous osteomyelitis, left shoulder.

M86.019 ✓ Billable — Acute hematogenous osteomyelitis, unspecified shoulder

Acute hematogenous osteomyelitis, unspecified shoulder.

What to Document

Acuity — acute, subacute, or chronic osteomyelitis (drives the 4th character).
The affected bone/site and laterality (5th-6th characters).
Whether the process is hematogenous or from another documented source (e.g., contiguous spread).

Common Documentation Pitfalls

Defaulting to M86.9 when the note documents the acuity or the affected bone.
Coding a soft-tissue infection as osteomyelitis without documented bone involvement.

Also Known As

Official ICD-10-CM Alphabetic Index terms that point to M86.9:

Osteomyelitis (general) (infective) (localized) (neonatal) (purulent) (septic) (staphylococcal) (streptococcal) (suppurative) (with periostitis)

Coding Notes

M86.9 is the unspecified default. When acuity and site are documented, use the specific M86 subcategory (e.g., acute hematogenous M86.0-) with the affected bone and laterality. Reserve M86.9 for records specifying neither type nor site.