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M87.878 ICD-10-CM Code: Other osteonecrosis, left toe(s)

M87.878 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 lookupM87.878

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

M87.878

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

Other osteonecrosis, left toe(s)

Death of bone tissue in the left toe(s) due to causes other than trauma, infection, or radiation. This can cause pain and difficulty walking or wearing shoes.

Buddy the Bee presenting code insight

Buddy Insight

Left toe osteonecrosis represents avascular bone death in the toe bones, potentially disrupting normal gait mechanics and balance.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 92

Coefficient HCC 92: 0.479 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 055

Code-level coefficient reference

ESRD/PACE

HCC 39

Code-level coefficient reference

RXHCC

HCC 80

Code-level coefficient reference

Code Book Path

Official
M87.8Other osteonecrosisM87.87Other osteonecrosis, ankle, foot and toesM87.878Other osteonecrosis, left toe(s)

Inclusion Terms

Official

No inclusion terms are included in this display for M87.878. 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
M87.871Other osteonecrosis, right ankleM87.872Other osteonecrosis, left ankleM87.873Other osteonecrosis, unspecified ankleM87.874Other osteonecrosis, right footM87.875Other osteonecrosis, left foot

Includes

Official
  • avascular necrosis of boneInherited from M87

Excludes 1

Official
  • postprocedural osteopathies (M96.-)Inherited from M86-M90, M87
  • juvenile osteonecrosis (M91-M92)Inherited from M86-M90, M87
  • osteochondropathies (M90-M93)Inherited from M86-M90, M87

Code First

Official

No Code First sequencing instructions are included in this display for M87.878. Check the code and parent instructions in the Code Book.

Use Additional

Official
  • code to identify major osseous defect, if applicable (M89.7-)Inherited from M87

Code Also

Official

No Code Also instructions are included in this display for M87.878. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance
Clear documentation of left toe(s) involvement
Radiological evidence of bone necrosis in affected toes
Exclusion of traumatic, infectious, or radiation-induced etiology
Gait analysis and balance assessment impact

MEAT Support

HCC Buddy guidance
Clear documentation of left toe(s) involvement
Radiological evidence of bone necrosis in affected toes
Exclusion of traumatic, infectious, or radiation-induced etiology
Gait analysis and balance assessment impact

Audit Caution

HCC Buddy guidance
Confusing left and right toe laterality
Misclassifying acute injuries as chronic osteonecrosis
Missing diabetic or vascular complications
Incorrectly coding structural deformities as osteonecrosis

Common Mistakes

HCC Buddy guidance
M87.378 — Drug-induced osteonecrosis requires specific agent identification
M87.178 — Post-traumatic osteonecrosis needs trauma documentation
M87.078 — Idiopathic osteonecrosis has no identifiable precipitating factors
S92.502A — Left toe fracture is acute injury code

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 M87.878 an HCC code?

Yes. M87.878 (Other osteonecrosis, left toe(s)) 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: M87.878 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
M87.878
Description
Other osteonecrosis, left toe(s)
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 M87.878 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for M87.878

For M87.878, 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

M87.878 is the ICD-10-CM diagnosis code for other osteonecrosis, left toe(s). Death of bone tissue in the left toe(s) due to causes other than trauma, infection, or radiation. This can cause pain and difficulty walking or wearing shoes. M87.878 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, M87.878 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 M87.878; 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.

This code is specific to the left toe(s); use M87.877 for right toe(s) or M87.879 for unspecified. For M87.878, 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 M87.878 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •This code is specific to the left toe(s); use M87.877 for right toe(s) or M87.879 for unspecified
  • •Document which toe(s) are affected if possible, though this code does not differentiate between individual toes

Clinical Significance

Left toe osteonecrosis represents avascular bone death in the toe bones, potentially disrupting normal gait mechanics and balance. This condition requires careful management to prevent complications and preserve foot function, especially in patients with comorbid conditions like diabetes.

Documentation Requirements

  • ✓Clear documentation of left toe(s) involvement
  • ✓Radiological evidence of bone necrosis in affected toes
  • ✓Exclusion of traumatic, infectious, or radiation-induced etiology
  • ✓Gait analysis and balance assessment impact
  • ✓Pain quantification and mobility limitations
  • ✓Screening for underlying vascular or metabolic conditions
  • ✓Specialized footwear and orthotic recommendations
  • ✓Regular monitoring for secondary complications

Commonly Confused Codes

  • •M87.378: Drug-induced osteonecrosis requires specific agent identification
  • •M87.178: Post-traumatic osteonecrosis needs trauma documentation
  • •M87.078: Idiopathic osteonecrosis has no identifiable precipitating factors
  • •S92.502A: Left toe fracture is acute injury code
  • •M20.12: Hallux valgus is structural deformity, not bone death

Child Codes

M87.871Other osteonecrosis, right ankle
HCC 92
M87.872Other osteonecrosis, left ankle
HCC 92
M87.873Other osteonecrosis, unspecified ankle
HCC 92
M87.874Other osteonecrosis, right foot
HCC 92
M87.875Other osteonecrosis, left foot
HCC 92
M87.876Other osteonecrosis, unspecified foot
HCC 92
M87.877Other osteonecrosis, right toe(s)
HCC 92
M87.878Other osteonecrosis, left toe(s)
HCC 92
M87.879Other osteonecrosis, unspecified toe(s)
HCC 92

Code Hierarchy

└M87Osteonecrosis└M87.8Other osteonecrosis└M87.87Other osteonecrosis, ankle, foot and toes└M87.878Other osteonecrosis, left toe(s)
└M87.878Other osteonecrosis, left toe(s)

Also searched as

  • M87 878
  • M87878

For M87.878, 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.

M87.878 maps to CMS-HCC V28 category 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for M87.878. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

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