2027 ICD-10-CM Diagnosis Code M46.20Osteomyelitis of vertebra, site unspecified
ICD-10-CM Codes›M00–M99›M45-M49›M46
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 92
- Not Chronic
M46.20 is a billable ICD-10-CM diagnosis code for osteomyelitis of vertebra, site 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 221 closely related codes. The code is flagged as an unspecified code, since codes identifying laterality exist in the same family. Coders also document this condition as acute hematogenous osteomyelitis of spine. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Osteomyelitis.
For Medicare Advantage risk adjustment, M46.20 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
Code EditsBilling
Medicare Code Editor checks that affect claim validity for M46.20.
Medicare Risk Adjustment (HCC)Billing
M46.20 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.
- Acute hematogenous osteomyelitis of spine
- Acute osteomyelitis of vertebra
- Chronic osteomyelitis of vertebra
- Infection of vertebra
- Osteomyelitis of vertebra
- Parasitic infection of vertebra
- Vertebral abscess
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to M46.20: its own notes plus those printed at Chapter 13. A note printed at a category, block or chapter applies to every code under it.
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)
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 M46.20, its category, or a range that includes it.
Excludes1 1
These codes carry an Excludes1 note naming M46.20: they are not reported together with it, unless the two conditions are unrelated.
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.
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 M46.20 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M46.20Overview
What is the ICD-10 code for osteomyelitis of vertebra, site unspecified?
The ICD-10-CM code for osteomyelitis of vertebra, site unspecified is M46.20 (sometimes written as M4620). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is M46.20 (Osteomyelitis of vertebra) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report osteomyelitis of vertebra, site unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does M46.20 group to?
When osteomyelitis of vertebra, site 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 M46.20 a CC or MCC?
CMS lists M46.20 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 221 closely related codes in its exclusion list.
What is the ICD-9 equivalent of M46.20?
Under the General Equivalence Mappings, osteomyelitis of vertebra, site unspecified converts to ICD-9-CM 730.28 (osteomyelit NOS-oth site). The mapping is approximate, so confirm the match fits the documentation.
What HCC is M46.20?
M46.20 (osteomyelitis of vertebra, site 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 M46.20 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, M46.20 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.
