What is ICD-10 code M01.X31?

M01.X31 is the ICD-10-CM diagnosis code for Direct infection of right wrist in infectious and parasitic diseases classified elsewhere. Direct infection of the right wrist joint resulting from an infectious or parasitic disease classified elsewhere. M01.X31 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. M01.X31 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.X31 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.X31 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.X31 map to under V28?

M01.X31 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.X31: Direct infection of right

M01.X31 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

ICD-10-CM Code View

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Code lookupM01.X31

Effective 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.X31

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

Direct infection of right wrist in infectious and parasitic diseases classified elsewhere

Direct infection of the right wrist joint resulting from an infectious or parasitic disease classified elsewhere.

Buddy Insight

Direct infection of the right wrist joint secondary to classified infectious or parasitic diseases represents a complex condition affecting fine motor function and hand dexterity.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

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.X3Direct infection of wrist in infectious and parasitic diseases classified elsewhere M01.X31Direct infection of right wrist in infectious and parasitic diseases classified elsewhere

Inclusion Terms

Official

Direct infection of carpal bones in infectious and parasitic diseases classified elsewhereInherited from M01.X3

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

M01.X32Direct infection of left wrist in infectious and parasitic diseases classified elsewhere M01.X39Direct infection of unspecified wrist in infectious and parasitic diseases classified elsewhere

Includes

Official

No Includes notes are included in this display for M01.X31. Check the code and parent instructions in the Code Book.

Excludes 1

Official

arthropathy in Lyme disease (A69.23)Inherited from M01
gonococcal arthritis (A54.42)Inherited from M01
meningococcal arthritis (A39.83)Inherited from M01
mumps arthritis (B26.85)Inherited from M01
postinfective arthropathy (M02.-)Inherited from M01
postmeningococcal arthritis (A39.84)Inherited from M01
reactive arthritis (M02.3)Inherited from M01
rubella arthritis (B06.82)Inherited from M01
sarcoidosis arthritis (D86.86)Inherited from M01
typhoid fever arthritis (A01.04)Inherited from M01
tuberculosis arthritis (A18.01-A18.02)Inherited from M01

Code First

Official

underlying disease, such as:Inherited from M01
leprosy [Hansen's disease] (A30.-)Inherited from M01
mycoses (B35-B49)Inherited from M01
O'nyong-nyong fever (A92.1)Inherited from M01
paratyphoid fever (A01.1-A01.4)Inherited from M01

Use Additional

Official

No Use Additional Code instructions are included in this display for M01.X31. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for M01.X31. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Clear documentation of right wrist joint infection

Primary diagnosis of underlying infectious or parasitic disease (A00-B99)

Evidence of direct causal relationship between systemic disease and joint infection

Physical examination documenting wrist joint inflammation and functional limitation

MEAT Support

HCC Buddy guidance

Clear documentation of right wrist joint infection

Primary diagnosis of underlying infectious or parasitic disease (A00-B99)

Evidence of direct causal relationship between systemic disease and joint infection

Physical examination documenting wrist joint inflammation and functional limitation

Audit Caution

HCC Buddy guidance

Incorrect laterality specification (confusing right and left wrist)

Omitting the required underlying infectious disease code as primary diagnosis

Using for secondary bacterial superinfection rather than direct extension

Misapplying when wrist involvement is inflammatory rather than directly infectious

Common Mistakes

HCC Buddy guidance

M00.931 — Pyogenic arthritis, right wrist (bacterial infection not from classified disease)

M25.531 — Pain in right wrist (joint pain without infectious etiology)

M01.X32 — Direct infection of left wrist in infectious diseases classified elsewhere

A18.02 — Tuberculous arthritis (when tuberculosis is the specific underlying cause)

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.X31 an HCC code?

Yes. M01.X31 (Direct infection of right wrist 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.X31 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.X31
Description: Direct infection of right wrist 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.X31 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for M01.X31

For M01.X31, 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

M01.X31 is the ICD-10-CM diagnosis code for direct infection of right wrist in infectious and parasitic diseases classified elsewhere. Direct infection of the right wrist joint resulting from an infectious or parasitic disease classified elsewhere. M01.X31 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.X31 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.X31; 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.

Requires a primary code from Chapter 1 (A00-B99) for the underlying infectious disease. For M01.X31, 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 M01.X31 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Requires a primary code from Chapter 1 (A00-B99) for the underlying infectious disease
•The 'X' placeholder indicates this describes a manifestation of another condition

Clinical Significance

Direct infection of the right wrist joint secondary to classified infectious or parasitic diseases represents a complex condition affecting fine motor function and hand dexterity. This diagnosis requires comprehensive management addressing both the underlying systemic infection and preservation of wrist joint function.

Documentation Requirements

✓Clear documentation of right wrist joint infection
✓Primary diagnosis of underlying infectious or parasitic disease (A00-B99)
✓Evidence of direct causal relationship between systemic disease and joint infection
✓Physical examination documenting wrist joint inflammation and functional limitation
✓Laboratory evidence of infection (elevated white count, inflammatory markers)
✓Imaging studies confirming wrist joint involvement (X-ray, MRI, ultrasound)
✓Joint aspiration and synovial fluid analysis when performed
✓Treatment plan for both systemic infection and joint-specific interventions

Commonly Confused Codes

•M00.931: Pyogenic arthritis, right wrist (bacterial infection not from classified disease)
•M25.531: Pain in right wrist (joint pain without infectious etiology)
•M01.X32: Direct infection of left wrist in infectious diseases classified elsewhere
•A18.02: Tuberculous arthritis (when tuberculosis is the specific underlying cause)