What is ICD-10 code M90.59?

M90.59 is the ICD-10-CM diagnosis code for Osteonecrosis in diseases classified elsewhere, multiple sites. Bone death (osteonecrosis) affecting multiple bone sites caused by another disease. The bone tissue dies in several locations as a secondary effect of an underlying condition. M90.59 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. M90.59 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. M90.59 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. M90.59 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does M90.59 map to under V28?

M90.59 maps to CMS-HCC V28 HCC 92 (Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM M90.59: Osteonecrosis in diseases

M90.59 maps to CMS-HCC V28 92. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · free HCC coding tools

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Code lookupM90.59

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Other osteopathies (M86-M90)

M90.59

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Osteonecrosis in diseases classified elsewhere, multiple sites

Bone death (osteonecrosis) affecting multiple bone sites caused by another disease. The bone tissue dies in several locations as a secondary effect of an underlying condition.

Buddy Insight

Secondary osteonecrosis affecting multiple anatomical sites represents widespread bone death caused by an underlying systemic disease, indicating severe medical complexity.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 92

Bone/Joint/Muscle/Severe Soft...

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 055

HHS-HCC 055 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 39

Bone/Joint/Muscle Infections/...

Code-level coefficient reference

RXHCC

Mapped

HCC 80

Aseptic Necrosis of Bone

Code-level coefficient reference

Code Book Path

Official

M90Osteopathies in diseases classified elsewhere M90.5Osteonecrosis in diseases classified elsewhere M90.59Osteonecrosis in diseases classified elsewhere, multiple sites

Inclusion Terms

Official

No inclusion terms are included in this display for M90.59. Check the code and parent instructions in the Code Book.

Excludes 2

Official

arthropathic psoriasis (L40.5-)Inherited from M00-M99
certain conditions originating in the perinatal period (P04-P96)Inherited from M00-M99
certain infectious and parasitic diseases (A00-B99)Inherited from M00-M99
compartment syndrome (traumatic) (T79.A-)Inherited from M00-M99
complications of pregnancy, childbirth and the puerperium (O00-O9A)Inherited from M00-M99
congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)Inherited from M00-M99
endocrine, nutritional and metabolic diseases (E00-E88)Inherited from M00-M99
injury, poisoning and certain other consequences of external causes (S00-T88)Inherited from M00-M99
neoplasms (C00-D49)Inherited from M00-M99
symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)Inherited from M00-M99

Related Codes

Official

M90.50Osteonecrosis in diseases classified elsewhere, unspecified site M90.51Osteonecrosis in diseases classified elsewhere, shoulder M90.52Osteonecrosis in diseases classified elsewhere, upper arm M90.53Osteonecrosis in diseases classified elsewhere, forearm M90.54Osteonecrosis in diseases classified elsewhere, hand

Includes

Official

No Includes notes are included in this display for M90.59. Check the code and parent instructions in the Code Book.

Excludes 1

Official

postprocedural osteopathies (M96.-)Inherited from M86-M90, M90
osteochondritis, osteomyelitis, and osteopathy (in):Inherited from M86-M90, M90
cryptococcosis (B45.3)Inherited from M86-M90, M90
diabetes mellitus (E08-E13 with .69-)Inherited from M86-M90, M90
gonococcal (A54.43)Inherited from M86-M90, M90
neurogenic syphilis (A52.11)Inherited from M86-M90, M90
renal osteodystrophy (N25.0)Inherited from M86-M90, M90
salmonellosis (A02.24)Inherited from M86-M90, M90
secondary syphilis (A51.46)Inherited from M86-M90, M90
syphilis (late) (A52.77)Inherited from M86-M90, M90

Code First

Official

underlying disease, such as:Inherited from M90.5
caisson disease (T70.3)Inherited from M90.5
hemoglobinopathy (D50-D64)Inherited from M90.5

Use Additional

Official

No Use Additional Code instructions are included in this display for M90.59. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for M90.59. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Documentation of underlying classified disease causing widespread osteonecrosis

Clear evidence of bone necrosis affecting multiple anatomical sites

Imaging studies confirming osteonecrotic changes in multiple locations

Clinical correlation between systemic disease and multifocal bone death

MEAT Support

HCC Buddy guidance

Documentation of underlying classified disease causing widespread osteonecrosis

Clear evidence of bone necrosis affecting multiple anatomical sites

Imaging studies confirming osteonecrotic changes in multiple locations

Clinical correlation between systemic disease and multifocal bone death

Audit Caution

HCC Buddy guidance

Not documenting and coding the underlying disease causing the osteonecrosis

Using when only single site involvement is documented

Failing to establish causal relationship between primary disease and bone death

Coding when documentation suggests possible rather than confirmed multiple sites

Common Mistakes

HCC Buddy guidance

M87.09 — Primary osteonecrosis of multiple sites, not secondary to disease

M90.58 — Same condition but affecting single other site rather than multiple sites

M86.19 — Chronic osteomyelitis of multiple sites involving infection

M89.09 — Other specified disorders of bone affecting multiple sites

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is M90.59 an HCC code?

Yes. M90.59 (Osteonecrosis in diseases classified elsewhere, multiple sites) maps to HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.479. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: M90.59 is billable and maps to V28 HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: M90.59
Description: Osteonecrosis in diseases classified elsewhere, multiple sites
HCC (V28): HCC 92 — Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis
RAF reference coefficient: 0.479
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis

0.479

ESRDHCC 39, Bone/Joint/Muscle Infections/Necrosis

Not separately weighted

RxHCCHCC 80, Aseptic Necrosis of Bone

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work M90.59 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for M90.59

For M90.59, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Coder workflow notes

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What This Code Means

M90.59 is the ICD-10-CM diagnosis code for osteonecrosis in diseases classified elsewhere, multiple sites. Bone death (osteonecrosis) affecting multiple bone sites caused by another disease. The bone tissue dies in several locations as a secondary effect of an underlying condition. M90.59 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering other osteopathies (m86-m90).

Under the CMS-HCC V28 risk adjustment model, M90.59 maps to Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis (HCC 92) with a source-labeled community, non-dual, aged reference coefficient of 0.479. No V24 mapping is shown for M90.59; use the applicable model and payment year when reviewing the V28 mapping. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Use this code when osteonecrosis is documented in multiple sites rather than a single location. For M90.59, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for M90.59 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Use this code when osteonecrosis is documented in multiple sites rather than a single location
•Always pair with a secondary diagnosis code for the underlying disease causing the osteonecrosis

Clinical Significance

Secondary osteonecrosis affecting multiple anatomical sites represents widespread bone death caused by an underlying systemic disease, indicating severe medical complexity. This diagnosis has major risk adjustment implications due to extensive functional limitations and intensive care coordination requirements.

Documentation Requirements

✓Documentation of underlying classified disease causing widespread osteonecrosis
✓Clear evidence of bone necrosis affecting multiple anatomical sites
✓Imaging studies confirming osteonecrotic changes in multiple locations
✓Clinical correlation between systemic disease and multifocal bone death
✓Comprehensive treatment plan addressing systemic condition and multiple sites
✓Assessment of cumulative functional impact from multiple site involvement
✓Provider documentation confirming secondary nature and multiple site involvement
✓Monitoring plan for progression and treatment response across sites

Commonly Confused Codes

•M87.09: Primary osteonecrosis of multiple sites, not secondary to disease
•M90.58: Same condition but affecting single other site rather than multiple sites
•M86.19: Chronic osteomyelitis of multiple sites involving infection
•M89.09: Other specified disorders of bone affecting multiple sites
•M85.89: Other specified disorders of bone density affecting multiple sites