M86.8X3 ICD-10-CM Code: Other osteomyelitis, forearm
M86.8X3 maps to CMS-HCC V28 92. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · free HCC coding tools
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FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Other osteopathies (M86-M90)
M86.8X3
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceOther osteomyelitis, forearm
A bone infection (osteomyelitis) affecting the forearm (radius and/or ulna) that doesn't fit into other specific osteomyelitis categories.
Buddy Insight
Other osteomyelitis of the forearm represents bone infection affecting the radius and/or ulna that doesn't conform to typical acute or chronic patterns.
CMS-HCC V28
MappedHCC 92
Code-level coefficient reference
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
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for M86.8X3 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for M86.8X3 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for M86.8X3 in this effective period.
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for M86.8X3 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for M86.8X3 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for M86.8X3 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for M86.8X3 in this effective period.
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 M86.8X3 an HCC code?
Yes. M86.8X3 (Other osteomyelitis, forearm) 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: M86.8X3 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
- M86.8X3
- Description
- Other osteomyelitis, forearm
- 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 M86.8X3 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT Criteria for M86.8X3
For M86.8X3 to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.
- 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
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed M86.8X3 during that encounter, not just copy-forwarded from a problem list.
Coder workflow notes
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What This Code Means
M86.8X3 is the ICD-10-CM diagnosis code for other osteomyelitis, forearm. A bone infection (osteomyelitis) affecting the forearm (radius and/or ulna) that doesn't fit into other specific osteomyelitis categories. M86.8X3 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, M86.8X3 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 M86.8X3; use the applicable model and payment year when reviewing the V28 mapping. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. 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.
Document which bone(s) of the forearm are affected for clinical clarity, though the code encompasses both radius and ulna. Because M86.8X3 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. 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 M86.8X3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document which bone(s) of the forearm are affected for clinical clarity, though the code encompasses both radius and ulna
- •Ensure this is not acute or chronic osteomyelitis before assigning this 'other' category code
Clinical Significance
Other osteomyelitis of the forearm represents bone infection affecting the radius and/or ulna that doesn't conform to typical acute or chronic patterns. This condition can severely impact hand and wrist function due to the forearm's critical role in rotation and fine motor activities, requiring specialized treatment to preserve upper extremity function.
Documentation Requirements
- ✓Documentation of osteomyelitis affecting forearm bones
- ✓Clinical justification for 'other' classification
- ✓Specification of radius and/or ulna involvement
- ✓Supporting imaging demonstrating bone infection
- ✓Culture results or histopathological confirmation when available
- ✓Comprehensive treatment plan including antimicrobials
- ✓Assessment of forearm rotation and hand function
- ✓Documentation of atypical presentation features