2027 ICD-10-CM Diagnosis Code M86.9Osteomyelitis, unspecified
ICD-10-CM Codes›M00–M99›M86-M90›M86
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 92
- Not Chronic
M86.9 is a billable ICD-10-CM diagnosis code for osteomyelitis, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 456 through 458, 539 through 541. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 168 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Osteomyelitis.
For Medicare Advantage risk adjustment, M86.9 maps to CMS-HCC Category 92 (Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis) under the V28 model, adding a risk factor of about 0.479 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
M86.9 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 2027.
Source: CMS Payment Year 2027 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.
- Bacterial osteomyelitis
- Bone abscess
- Coccidioidomycosis of bone
- Cranial cerebrospinal fluid leak
- Enthesitis
- Infection by Pasteurella multocida
- Infection due to and following fracture of bone
- Infection of bone
- Infection of bone associated with bone plate
- Infection of bone associated with bone screw
- Infection of bone of ankle and/or foot
- Infection of bone of hand
- Infection of bone of radius and/or ulna
- Infection of bone of tibia and/or fibula
- Infection of calcaneum
- Infection of carpal bone
- Infection of femur
- Infection of fibula
- Infection of humerus
- Infection of metacarpal
- Infection of metatarsal
- Infection of multiple bones
- Infection of patella
- Infection of pelvis
- Infection of phalanx of finger or thumb
- Infection of phalanx of toe
- Infection of radius
- Infection of scapula
- Infection of talus
- Infection of ulna
- Leak of cranial cerebrospinal fluid due to osteomyelitis
- Osteitis
- Osteitis of hand
- Osteitis of left femur
- Osteitis of lower leg
- Osteitis of multiple sites
- Osteitis of pelvis
- Osteitis of right femur
- Osteitis of shoulder region
- Osteomyelitis
- Osteomyelitis caused by Staphylococcus aureus
- Osteomyelitis due to type 1 diabetes mellitus
- Osteomyelitis of ankle
- Osteomyelitis of clavicle
- Osteomyelitis of cranium
- Osteomyelitis of facial bone
- Osteomyelitis of forearm
- Osteomyelitis of forefoot
- Osteomyelitis of frontal bone
- Osteomyelitis of hand
- Osteomyelitis of hindfoot
- Osteomyelitis of left ankle
- Osteomyelitis of left femur
- Osteomyelitis of left foot
- Osteomyelitis of left hand
- Osteomyelitis of left shoulder
- Osteomyelitis of left tibia
- Osteomyelitis of lower leg
- Osteomyelitis of midfoot
- Osteomyelitis of multiple sites
- Osteomyelitis of pelvic region
- Osteomyelitis of right ankle
- Osteomyelitis of right femur
- Osteomyelitis of right foot
- Osteomyelitis of right hand
- Osteomyelitis of right shoulder
- Osteomyelitis of right tibia
- Osteomyelitis of sphenoid bone
- Osteomyelitis of temporal bone
- Osteomyelitis of tibia
- Osteomyelitis of upper arm
- Osteomyelitis of upper limb
- Osteomyelitis of zygomatic bone
- Pasteurella multocida osteomyelitis
- Pedal osteitis
- Periostitis
- Periostitis of forearm
- Periostitis of forearm without osteomyelitis
- Periostitis of hand
- Periostitis of hand without osteomyelitis
- Periostitis without osteomyelitis
- Periostitis without osteomyelitis of cervical spine
- Periostitis without osteomyelitis of coccyx
- Periostitis without osteomyelitis of lumbar spine
- Periostitis without osteomyelitis of sacral vertebra
- Periostitis without osteomyelitis of thoracic spine
- SAPHO syndrome
- Sternal osteomyelitis
- Tenoperiostitis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to M86.9: its own notes plus those printed at M86, block M86-M90, and Chapter 13. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Infection of bone NOS
- Periostitis without osteomyelitis
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- postprocedural osteopathies (M96.-)
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- arthropathic psoriasis (L40.5-)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- compartment syndrome (traumatic) (T79.A-)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
Notes
General instructions on how these codes are used.
- Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name M86.9, its category, or a range that includes it.
Code First 1
These codes say to code first a condition named in the note, and M86.9 is one of the conditions named.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Osteomyelitis
inflammation of the bone as a result of infection. it may be caused by a variety of infectious agents, especially pyogenic (pus - producing) bacteria.
Patient EducationClinical
Bone Infections
Like other parts of the body, bones can get infected. The infections are usually bacterial, but can also be fungal. They may spread to the bone from nearby skin or muscles, or from another part of the body through the bloodstream.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert M86.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M86.9Overview
What is the ICD-10 code for osteomyelitis, unspecified?
The ICD-10-CM code for osteomyelitis, unspecified is M86.9 (sometimes written as M869). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is M86.9 (Osteomyelitis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report osteomyelitis, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does M86.9 group to?
When osteomyelitis, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 541, 456, 457, 539, 540, 458, with relative weights from 0.8293 to 7.6211 depending on complications. Higher weights mean higher Medicare reimbursement.
Is M86.9 a CC or MCC?
CMS lists M86.9 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 168 closely related codes in its exclusion list.
Can M86.9 be reported with B67.2?
Not as a rule. The Excludes1 note at M86, which applies to M86.9, lists "echinococcus (B67.2)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is M86.9?
M86.9 (osteomyelitis, unspecified) maps to CMS-HCC Category 92 (Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis), commonly written as HCC 92, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 39 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does M86.9 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, M86.9 adds a risk adjustment factor of about 0.479 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.471 to 0.632 depending on the payment segment). HCC 92 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 92 category page.
