M87.378 ICD-10-CM Code: Other secondary osteonecrosis, left toe(s)
M87.378 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 · HCC Buddy coding tools
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FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Other osteopathies (M86-M90)
M87.378
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceOther secondary osteonecrosis, left toe(s)
Death of bone tissue in the left toe(s) caused by an underlying condition or treatment such as corticosteroid use or radiation therapy.
Buddy Insight
This diagnosis represents secondary osteonecrosis of the left toe bones caused by underlying conditions such as corticosteroid use or radiation therapy, which can affect toe function and potentially impact walking.
CMS-HCC V28
MappedHCC 92
Coefficient HCC 92: 0.479 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 055
Code-level coefficient reference
ESRD/PACE
MappedHCC 39
Code-level coefficient reference
RXHCC
MappedHCC 80
Code-level coefficient reference
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for M87.378. 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
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
OfficialNo Code First sequencing instructions are included in this display for M87.378. 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
OfficialNo Code Also instructions are included in this display for M87.378. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
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 M87.378 an HCC code?
Yes. M87.378 (Other secondary 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: M87.378 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
- M87.378
- Description
- Other secondary 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
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 M87.378 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for M87.378
For M87.378, 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
M87.378 is the ICD-10-CM diagnosis code for other secondary osteonecrosis, left toe(s). Death of bone tissue in the left toe(s) caused by an underlying condition or treatment such as corticosteroid use or radiation therapy. M87.378 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, M87.378 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. 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.
Specify which toe(s) are involved and whether one or multiple toes are affected. For M87.378, 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 M87.378 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Specify which toe(s) are involved and whether one or multiple toes are affected
- •Document the underlying etiology and any functional impairment related to the osteonecrosis
Clinical Significance
This diagnosis represents secondary osteonecrosis of the left toe bones caused by underlying conditions such as corticosteroid use or radiation therapy, which can affect toe function and potentially impact walking. It requires management of the underlying cause and monitoring for progression.
Documentation Requirements
- ✓Documentation of osteonecrosis affecting left toe(s)
- ✓Identification of underlying cause (e.g., corticosteroid use, radiation therapy, vascular disease)
- ✓Imaging findings confirming toe bone necrosis (MRI, X-ray, CT)
- ✓Clinical symptoms such as toe pain, swelling, or deformity
- ✓Specific toe(s) affected if documented
- ✓Functional impact on walking or footwear
- ✓Duration and progression of condition
- ✓Treatment history and response to interventions
Commonly Confused Codes
- •M87.377: Other secondary osteonecrosis, right toe(s) (different laterality)
- •M87.379: Other secondary osteonecrosis, unspecified toe(s) (laterality not specified)
- •M86.172: Chronic osteomyelitis of left toe (infection vs necrosis)
- •S92.502A: Fracture of unspecified phalanx of left great toe (acute fracture vs necrosis)
- •M87.375: Other secondary osteonecrosis, left foot (foot vs toe specificity)