What is ICD-10 code M01.X49?

M01.X49 is the ICD-10-CM diagnosis code for Direct infection of unspecified hand in infectious and parasitic diseases classified elsewhere. An infection in the hand joint (side not specified) caused by a disease classified elsewhere, such as tuberculosis or a parasitic infection. M01.X49 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. M01.X49 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. M01.X49 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. M01.X49 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 M01.X49 map to under V28?

M01.X49 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 M01.X49: Direct infection

M01.X49 maps to CMS-HCC V28 92. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · HCC Buddy coding tools

ICD-10-CM Code View

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Code lookupM01.X49Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the musculoskeletal system and connective tissue (M00-M99) / Infectious arthropathies (M00-M02)

M01.X49

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

Direct infection of unspecified hand in infectious and parasitic diseases classified elsewhere

An infection in the hand joint (side not specified) caused by a disease classified elsewhere, such as tuberculosis or a parasitic infection.

Buddy Insight

This code represents direct hand joint infection secondary to classified infectious or parasitic diseases when laterality is not specified, indicating incomplete documentation.

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

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

M01.XDirect infection of joint in infectious and parasitic diseases classified elsewhere

M01.X4Direct infection of hand in infectious and parasitic diseases classified elsewhere

M01.X49Direct infection of unspecified hand in infectious and parasitic diseases classified elsewhere

Inclusion Terms

Official

Direct infection of metacarpus and phalanges in infectious and parasitic diseases classified elsewhere

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for M01.X49 in this effective period.

Related Child Codes

Official

M01.X41Direct infection of right hand in infectious and parasitic diseases classified elsewhere

M01.X42Direct infection of left hand in infectious and parasitic diseases classified elsewhere

Includes

Official

ICD-10-CM does not list Includes notes for M01.X49 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for M01.X49 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for M01.X49 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for M01.X49 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for M01.X49 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation of hand joint infection without laterality specification

Required primary code for underlying infectious or parasitic disease

Evidence that hand infection results from direct extension of classified disease

Physical examination findings consistent with infectious hand arthropathy

MEAT Support

HCC Buddy guidance

Documentation of hand joint infection without laterality specification

Required primary code for underlying infectious or parasitic disease

Evidence that hand infection results from direct extension of classified disease

Physical examination findings consistent with infectious hand arthropathy

Audit Caution

HCC Buddy guidance

Using unspecified laterality when side is documented in medical record

Failing to assign primary code for underlying infectious disease

Misapplying to secondary bacterial infections rather than direct extension

Not confirming that hand involvement is infectious rather than reactive

Common Mistakes

HCC Buddy guidance

M00.949 — Pyogenic arthritis, unspecified hand (bacterial infection not from classified disease)

M25.549 — Pain in unspecified hand (joint symptoms without infectious cause)

M01.X41 — Direct infection of right hand (when laterality is actually documented)

M01.X42 — Direct infection of left hand (when laterality is actually documented)

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 M01.X49 an HCC code?

Yes. M01.X49 (Direct infection of unspecified hand in infectious and parasitic diseases classified elsewhere) 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: M01.X49 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: M01.X49
Description: Direct infection of unspecified hand in infectious and parasitic diseases classified elsewhere
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

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 M01.X49 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for M01.X49

For M01.X49 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 M01.X49 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

M01.X49 is the ICD-10-CM diagnosis code for direct infection of unspecified hand in infectious and parasitic diseases classified elsewhere. An infection in the hand joint (side not specified) caused by a disease classified elsewhere, such as tuberculosis or a parasitic infection. M01.X49 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering infectious arthropathies (m00-m02).

Under the CMS-HCC V28 risk adjustment model, M01.X49 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 M01.X49; 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.

Use when the laterality of hand involvement is not documented or when both hands are affected. Because M01.X49 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 M01.X49 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Use when the laterality of hand involvement is not documented or when both hands are affected
•Must be accompanied by a secondary code identifying the underlying infectious or parasitic disease

Clinical Significance

This code represents direct hand joint infection secondary to classified infectious or parasitic diseases when laterality is not specified, indicating incomplete documentation. The condition poses significant risk for loss of essential hand function and requires comprehensive treatment to preserve manual dexterity and grip strength.

Documentation Requirements

✓Documentation of hand joint infection without laterality specification
✓Required primary code for underlying infectious or parasitic disease
✓Evidence that hand infection results from direct extension of classified disease
✓Physical examination findings consistent with infectious hand arthropathy
✓Laboratory studies indicating systemic infection and inflammation
✓Imaging confirmation of hand joint involvement
✓Microbiological data from joint samples when available
✓Treatment protocol addressing both underlying condition and hand infection

Commonly Confused Codes

•M00.949: Pyogenic arthritis, unspecified hand (bacterial infection not from classified disease)
•M25.549: Pain in unspecified hand (joint symptoms without infectious cause)
•M01.X41: Direct infection of right hand (when laterality is actually documented)
•M01.X42: Direct infection of left hand (when laterality is actually documented)