M87.9 ICD-10-CM Code: Osteonecrosis, unspecified

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for M87.9 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on M87.9 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for M87.9

MedCoder structured workflow — derived from this code’s own official record

Before you code M87.9

1. Unspecified does not mean incorrect. When the record gives no greater specificity, M87.9 may be the appropriate code. Check the record for detail that supports a more specific sibling. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

   See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

2. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with M87.9. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Does the record document the detail a more specific sibling code needs?
   Yes → Review the specific siblings in this subcategory.
   No → Continue — M87.9 is appropriate when the documentation goes no further.
2. Does the documentation support a condition named in M87.9’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

   ReviewM96

Consider M87.9. Then work the Use Additional Code note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

The conditions the Use Additional Code note names

Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Any detail beyond this code’s title

What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

• Excludes1 — check before selecting M87.9(3 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with M87.9: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareM96

  See the official tabular notes · Guidelines I.A.12.a

• Use Additional Code — after identifying M87.9(1 note)

  Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with M87.9 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

  ReviewM89.7

  See the official tabular notes · Guidelines I.A.13

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (2)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• Necrosis, necrotic (ischemic), bone
• Osteonecrosis

Official Coding Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Verbatim excerpts from the ICD-10-CM Official Guidelines for Coding and Reporting (CMS/NCHS) that govern this code.

Don’t confuse M87.9 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of M87.9 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• M91— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of juvenile osteonecrosis moves the case to M91; the two are not reported together unless documented as unrelated.

  Full comparison: M87.9 vs M91 →

• M92— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of juvenile osteonecrosis moves the case to M92; the two are not reported together unless documented as unrelated.

  Full comparison: M87.9 vs M92 →

• M90— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of osteochondropathies moves the case to M90; the two are not reported together unless documented as unrelated.

  Full comparison: M87.9 vs M90 →

• M93— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of osteochondropathies moves the case to M93; the two are not reported together unless documented as unrelated.

  Full comparison: M87.9 vs M93 →

• M96— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of postprocedural osteopathies moves the case to M96; the two are not reported together unless documented as unrelated.

  Full comparison: M87.9 vs M96 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name M87.9 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Code First instruction: M89.7 — Major osseous defect (via M87.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 217 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 553 (MDC 08), DRG 554 (MDC 08).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):MUS030 — Aseptic necrosis and osteonecrosis (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

M87.851 — Other osteonecrosis, right femur, M87.852 — Other osteonecrosis, left femur, M87.859 — Other osteonecrosis, unspecified femur, M87.861 — Other osteonecrosis, right tibia, M87.862 — Other osteonecrosis, left tibia, M87.863 — Other osteonecrosis, unspecified tibia, M87.864 — Other osteonecrosis, right fibula, M87.865 — Other osteonecrosis, left fibula, M87.869 — Other osteonecrosis, unspecified fibula, M87.871 — Other osteonecrosis, right ankle, M87.872 — Other osteonecrosis, left ankle, M87.873 — Other osteonecrosis, unspecified ankle, M87.874 — Other osteonecrosis, right foot, M87.875 — Other osteonecrosis, left foot, M87.876 — Other osteonecrosis, unspecified foot, M87.877 — Other osteonecrosis, right toe(s), M87.878 — Other osteonecrosis, left toe(s), M87.879 — Other osteonecrosis, unspecified toe(s), M87.88 — Other osteonecrosis, other site, M87.89 — Other osteonecrosis, multiple sites, +196 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis) for risk-adjusted payment.

M87.872 — Other osteonecrosis, left ankle, M87.873 — Other osteonecrosis, unspecified ankle, M87.874 — Other osteonecrosis, right foot, M87.875 — Other osteonecrosis, left foot, M87.876 — Other osteonecrosis, unspecified foot, M87.877 — Other osteonecrosis, right toe(s), M87.878 — Other osteonecrosis, left toe(s), M87.879 — Other osteonecrosis, unspecified toe(s), M87.88 — Other osteonecrosis, other site, M87.89 — Other osteonecrosis, multiple sites, M89.60 — Osteopathy after poliomyelitis, unspecified site, M89.611 — Osteopathy after poliomyelitis, right shoulder, M89.612 — Osteopathy after poliomyelitis, left shoulder, M89.619 — Osteopathy after poliomyelitis, unspecified shoulder, M89.621 — Osteopathy after poliomyelitis, right upper arm, M89.622 — Osteopathy after poliomyelitis, left upper arm, M89.629 — Osteopathy after poliomyelitis, unspecified upper arm, M89.631 — Osteopathy after poliomyelitis, right forearm, M89.632 — Osteopathy after poliomyelitis, left forearm, M89.639 — Osteopathy after poliomyelitis, unspecified forearm, +588 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Aseptic necrosis and osteonecrosis).

M87.872 — Other osteonecrosis, left ankle, M87.873 — Other osteonecrosis, unspecified ankle, M87.874 — Other osteonecrosis, right foot, M87.875 — Other osteonecrosis, left foot, M87.876 — Other osteonecrosis, unspecified foot, M87.877 — Other osteonecrosis, right toe(s), M87.878 — Other osteonecrosis, left toe(s), M87.879 — Other osteonecrosis, unspecified toe(s), M87.88 — Other osteonecrosis, other site, M87.89 — Other osteonecrosis, multiple sites, M90.50 — Osteonecrosis in diseases classified elsewhere, unspecified site, M90.511 — Osteonecrosis in diseases classified elsewhere, right shoulder, M90.512 — Osteonecrosis in diseases classified elsewhere, left shoulder, M90.519 — Osteonecrosis in diseases classified elsewhere, unspecified shoulder, M90.521 — Osteonecrosis in diseases classified elsewhere, right upper arm, M90.522 — Osteonecrosis in diseases classified elsewhere, left upper arm, M90.529 — Osteonecrosis in diseases classified elsewhere, unspecified upper arm, M90.531 — Osteonecrosis in diseases classified elsewhere, right forearm, M90.532 — Osteonecrosis in diseases classified elsewhere, left forearm, M90.539 — Osteonecrosis in diseases classified elsewhere, unspecified forearm, +258 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Necrosis, necrotic”, “Osteonecrosis”; these codes share that main term but sit in a different category of the Tabular List.

J98.09 — Other diseases of bronchus, not elsewhere classified (bronchus), K04.1 — Necrosis of pulp (pulp), K22.89 — Other specified disease of esophagus (esophagus), K31.89 — Other diseases of stomach and duodenum (stomach), K55.049 — Acute infarction of large intestine, extent unspecified (colon), K55.069 — Acute infarction of intestine, part and extent unspecified (omentum), K65.4 — Sclerosing mesenteritis (omentum, fat), K76.2 — Central hemorrhagic necrosis of liver (liver, hemorrhagic, central), K86.89 — Other specified diseases of pancreas (pancreas), M27.2 — Inflammatory conditions of jaws (jaw), N17.0 — Acute kidney failure with tubular necrosis (tubular), N17.1 — Acute kidney failure with acute cortical necrosis (cortical), N17.2 — Acute kidney failure with medullary necrosis (papillary), N17.9 — Acute kidney failure, unspecified (kidney, acute), N28.0 — Ischemia and infarction of kidney (kidney), N32.89 — Other specified disorders of bladder (bladder), N50.89 — Other specified disorders of the male genital organs (testis), N64.1 — Fat necrosis of breast (breast), N70.92 — Oophoritis, unspecified (ovary), N89.8 — Other specified noninflammatory disorders of vagina (vagina), +36 more

Contextual Map

Every relationship of M87.9 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run M87.9 with this related code in Claim Check

Hierarchy

• M00-M99 — Chapter 13: Diseases of the Musculoskeletal System and Connective Tissue (M00-M99) (M00-M99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M86-M90 — Other osteopathies[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Referenced by Code First instructions

• M89.7 — Major osseous defect[Code First](via M87.-): “aseptic necrosis of bone (M87.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• MUS030 — Aseptic necrosis and osteonecrosis[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

Risk adjustment (CMS-HCC)

• HCC 92 — Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 553 — BONE DISEASES AND ARTHROPATHIES WITH MCC[MS-DRG]: “BONE DISEASES AND ARTHROPATHIES WITH MCC (MDC 08)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 554 — BONE DISEASES AND ARTHROPATHIES WITHOUT MCC[MS-DRG]: “BONE DISEASES AND ARTHROPATHIES WITHOUT MCC (MDC 08)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 08 — Diseases and Disorders of the Musculoskeletal System and Connective Tissue[MDC crossing]: “Diseases and Disorders of the Musculoskeletal System and Connective Tissue — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 18,508 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Necrosis, necrotic (ischemic), bone[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Osteonecrosis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (40)

• M87 — Osteonecrosis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M87.831 — Other osteonecrosis of right radius[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M87.832 — Other osteonecrosis of left radius[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M87.833 — Other osteonecrosis of unspecified radius[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M87.834 — Other osteonecrosis of right ulna[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M87.835 — Other osteonecrosis of left ulna[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M87.836 — Other osteonecrosis of unspecified ulna[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• M87.837 — Other osteonecrosis of right carpus[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 32 more

Change history

• FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Coding guidelines Official source data

ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Risk adjustment Official source data

2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to M87.9 in its code family, with their registry titles.

• M87.871 — Other osteonecrosis, right ankle
• M87.872 — Other osteonecrosis, left ankle
• M87.873 — Other osteonecrosis, unspecified ankle
• M87.874 — Other osteonecrosis, right foot
• M87.875 — Other osteonecrosis, left foot
• M87.876 — Other osteonecrosis, unspecified foot
• M87.877 — Other osteonecrosis, right toe(s)
• M87.878 — Other osteonecrosis, left toe(s)
• M87.879 — Other osteonecrosis, unspecified toe(s)
• M87.88 — Other osteonecrosis, other site

View all codes in the M87 family