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M86.242 ICD-10-CM Code: Subacute osteomyelitis, left hand

M86.242 maps to CMS-HCC V28 92 (RAF 0.479). Documentation must support MEAT. MEAT criteria · RAF calculator · HCC coding software

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

M86.242

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

Subacute osteomyelitis, left hand

A bone infection in the left hand that develops over weeks to months, causing inflammation and potential bone damage.

Buddy the Bee presenting code insight

Buddy Insight

Subacute osteomyelitis of the left hand represents a bone infection with gradual onset affecting the complex hand anatomy over weeks to months.

CMS-HCC V28

HCC 92

RAF 0.479

CMS-HCC V24

HCC 39

RAF 0.401

ACA/HHS

HCC 55

Varies by metal level

ESRD/PACE

HCC 39

RAF 0.092

RXHCC

N/A

—

Not mapped

Code Book Path

Official
M86.2Subacute osteomyelitis
M86.24Subacute osteomyelitis, hand
M86.242Subacute osteomyelitis, left hand

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for M86.242 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for M86.242 in this effective period.

Related Child Codes

Official
M86.241Subacute osteomyelitis, right hand
M86.249Subacute osteomyelitis, unspecified hand

Includes

Official

ICD-10-CM does not list Includes notes for M86.242 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for M86.242 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for M86.242 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for M86.242 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for M86.242 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Specific identification of left hand bone involvement
Documentation of subacute infection timeline
Clinical evidence of hand bone infection
Imaging confirmation of osteomyelitis in hand bones

MEAT Support

HCC Buddy guidance
Specific identification of left hand bone involvement
Documentation of subacute infection timeline
Clinical evidence of hand bone infection
Imaging confirmation of osteomyelitis in hand bones

Audit Caution

HCC Buddy guidance
Confusing bone infection with soft tissue cellulitis
Missing subacute timeline significance
Not documenting functional impact on hand use
Confusing with traumatic hand injuries

Common Mistakes

HCC Buddy guidance
M86142 — Other acute osteomyelitis of left hand
M86642 — Chronic osteomyelitis with draining sinus of left hand
L03.112 — Cellulitis of left finger (soft tissue)
M86342 — Chronic multifocal osteomyelitis of left hand

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 M86.242 an HCC code?

Yes. M86.242 (Subacute osteomyelitis, left hand) maps to Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis under the CMS-HCC V28 risk adjustment model (and Bone/Joint/Muscle Infections/Necrosis under V24), with a community non-dual aged RAF of 0.479. It is billable for payment year 2026.

Coder answer: M86.242 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
M86.242
Description
Subacute osteomyelitis, left hand
HCC (V28)
HCC 92 — Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis
RAF
0.479
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 92, Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis
0.479
V24HCC 39, Bone/Joint/Muscle Infections/Necrosis
0.401
ESRDHCC 39, Bone/Joint/Muscle Infections/Necrosis
0.092

Each model's RAF is its CMS base weight for that model's standard population, so 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 segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

Work M86.242 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for M86.242

For M86.242 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 M86.242 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

M86.242 is the ICD-10-CM diagnosis code for subacute osteomyelitis, left hand. A bone infection in the left hand that develops over weeks to months, causing inflammation and potential bone damage. M86.242 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, M86.242 maps to Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis (HCC 92) with a community, non-dual, aged base RAF weight of 0.479. Under the older CMS-HCC V24 model, M86.242 maps to Bone/Joint/Muscle Infections/Necrosis (HCC 39) with a community, non-dual, aged base RAF weight of 0.401. 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.

Verify laterality is documented as 'left hand' in the clinical record before assigning this code. Because M86.242 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. 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, RAF weights, and MEAT documentation criteria for M86.242 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Verify laterality is documented as 'left hand' in the clinical record before assigning this code
  • •Confirm the infection is subacute (not acute or chronic) and document the specific bone affected when possible

Clinical Significance

Subacute osteomyelitis of the left hand represents a bone infection with gradual onset affecting the complex hand anatomy over weeks to months. This condition threatens fine motor function and grip strength, requiring careful treatment to preserve hand dexterity and prevent chronic disability.

Documentation Requirements

  • ✓Specific identification of left hand bone involvement
  • ✓Documentation of subacute infection timeline
  • ✓Clinical evidence of hand bone infection
  • ✓Imaging confirmation of osteomyelitis in hand bones
  • ✓Laboratory evidence of ongoing infection
  • ✓Assessment of hand function and grip strength
  • ✓Documentation of fine motor impact
  • ✓Treatment plan preserving hand mobility

Commonly Confused Codes

  • •M86142: Other acute osteomyelitis of left hand
  • •M86642: Chronic osteomyelitis with draining sinus of left hand
  • •L03.112: Cellulitis of left finger (soft tissue)
  • •M86342: Chronic multifocal osteomyelitis of left hand
  • •S62.92XA: Unspecified fracture of left wrist and hand

Child Codes

M86.241Subacute osteomyelitis, right hand
HCC 92
M86.242Subacute osteomyelitis, left hand
HCC 92
M86.249Subacute osteomyelitis, unspecified hand
HCC 92

Code Hierarchy

└M86Osteomyelitis└M86.2Subacute osteomyelitis└M86.24Subacute osteomyelitis, hand└M86.242Subacute osteomyelitis, left hand
└M86.242Subacute osteomyelitis, left hand

Because M86.242 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

M86.242 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. Because M86.242 carries a payment HCC, you can see what it adds to a RAF score and check the documentation the chart needs before it is submitted.

Work M86.242 in HCC Buddy

Open M86.242 in the Code Book for the full Index-to-Tabular path, MEAT checklist, and V28 HCC mapping, or in the Encoder to code from a keyword search. Pro includes 7 days to try everything, no card required.

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