ICD-10 Code M36.2: Hemophilic arthropathy

Key takeaways

M36.2 is the billable ICD-10-CM code for hemophilic arthropathy, valid for the 2026 code year (effective October 1, 2025)

M36.2 carries a Code first note, so the underlying hemophilia code (D66, D67, D68.0-, or D68.1) is always sequenced ahead of it

As a manifestation code in the M36 category, M36.2 can never be the principal or first-listed diagnosis

M36.2 has no Excludes note of its own. It inherits the M36 category Excludes2 for arthropathies in diseases classified elsewhere (M14.-)

Practice management software like Pabau keeps the Code first sequence and its supporting documentation intact across every encounter

ICD-10 Code M36.2 is the billable diagnosis code for hemophilic arthropathy, the joint disease caused by repeated bleeding in hemophilia. It carries a Code first note, which makes the underlying hemophilia code mandatory and puts it ahead of M36.2 on the claim.

Coders who treat that order as flexible, or who reach for M36.3 instead, produce avoidable denials. This reference covers what coders and clinicians treating hemophilia patients need to document and bill M36.2 accurately.

The 2026 edition of ICD-10-CM became effective October 1, 2025. It is maintained jointly by the Centers for Medicare and Medicaid Services (CMS) and the National Center for Health Statistics (NCHS). M36.2 is confirmed billable in that edition, and unchanged from the prior code year.

ICD-10 Code M36.2: definition and billable status

ICD-10 Code M36.2 describes hemophilic arthropathy. It is a billable and specific ICD-10-CM diagnosis code, meaning it carries sufficient clinical detail to be used directly on a claim without further specification. Coders can verify the current status using the CDC/NCHS official ICD-10-CM web tool.

The tabular list prints a single inclusion term under M36.2, and it reads hemarthrosis in hemophilic arthropathy. A joint bleed in a patient with established hemophilic arthropathy therefore belongs at M36.2. That is also why M25.0, the code for hemarthrosis, carries an Excludes1 note pointing at M36.2.

The code is not new to the 2026 edition. It has been a stable, billable code across multiple code years. Coders should confirm billable status annually against the current CMS tabular list, as status can change between code years.

Clinical description: what is hemophilic arthropathy?

Hemophilic arthropathy is a progressive joint disease caused by repeated hemarthrosis (bleeding into joints) in patients with hemophilia. Each bleeding episode triggers an inflammatory cascade that, over time, degrades cartilage, thickens synovium, and erodes subchondral bone.

Clinicians treating these patients in physical therapy and occupational therapy see a consistent pattern. It runs from chronic synovitis to loss of range of motion, and then to joint contracture.

The knee, elbow, and ankle are the joints most commonly affected, though any joint can be involved in severe hemophilia.

For documentation purposes, the clinical record should reflect the specific joint or joints affected. It should also name the hemophilia type and the evidence of the underlying coagulation disorder. This documentation underpins correct sequencing and supports medical necessity when a payer reviews the claim.

• Primary mechanism: Repeated hemarthrosis leads to iron deposition in synovial tissue, synovial hypertrophy, and cartilage destruction
• Most affected joints: Knee (most common), elbow, ankle, hip, and shoulder
• Underlying disorders: Hemophilia A (factor VIII deficiency), Hemophilia B (factor IX deficiency), Hemophilia C (factor XI deficiency, less common)
• Clinical stages: Acute hemarthrosis, chronic synovitis, established arthropathy with joint destruction

Code first instructions for ICD-10 Code M36.2

M36.2 carries a Code first note. It does not carry a Code also note, and that distinction changes how the claim is built. A Code first note dictates sequencing, so the underlying disease is always reported before M36.2. A Code also note carries no sequencing direction at all.

The note printed under M36.2 in the FY2026 tabular list names the qualifying underlying diseases:

• Factor VIII deficiency (D66)
• With vascular defect (D68.0-)
• Factor IX deficiency (D67)
• Hemophilia, classical (D66)
• Hemophilia B (D67)
• Hemophilia C (D68.1)

Reporting the underlying disease is mandatory, and so is the order. Official Guideline I.A.13 sets out the etiology and manifestation convention, where the underlying condition is sequenced first and the manifestation code follows.

M36.2 sits in category M36, which covers connective tissue disorders in diseases classified elsewhere. No code in that category is ever reported as the principal or first-listed diagnosis.

The table below maps each Code first option to the clinical picture behind it.

The order does not depend on the reason for the encounter. That is the practical difference between the two conventions, since a Code also note leaves sequencing to the circumstances of the visit.

The Alphabetic Index makes the same point in shorthand, listing the hemophilia entry as D66 [M36.2]. A code in brackets is a manifestation code, and it is always sequenced second.

Incorrect sequencing is a leading cause of denials for this code pair. Practices using claims management software that validates code order at the point of entry can catch the error before submission.

Excludes notes that apply to M36.2

M36.2 has no Excludes1 or Excludes2 note of its own. The only Excludes2 note in play sits on the parent category M36, and every code in that category inherits it. It excludes arthropathies in diseases classified elsewhere (M14.-).

Two further notes name M36.2 from the outside, and both are Excludes1. Good clinical documentation practices at the point of care keep these boundaries clear.

The two note types are not interchangeable. Excludes1 means the conditions are mutually exclusive and cannot be reported together for the same encounter. Excludes2 means the excluded condition is not part of the code, but a patient may have both, so both codes are reportable when documented.

How M36.2 differs from M36.3

Nothing in the tabular list places an Excludes relationship between M36.2 and M36.3. They are adjacent codes in the same category, and each carries its own Code first list. M36.3 covers arthropathy in other blood disorders, and its note points to blood disorder unspecified (D75.9), other hemoglobinopathies (D58.2), and thalassemia (D56.-).

The choice between them turns on documented etiology, not on severity or on which joint is involved. Hemophilia named as the cause sends you to M36.2. Another blood disorder, such as sickle cell disease or thalassemia, sends you to M36.3. Both codes can appear on one claim when a patient genuinely has two distinct arthropathies.

Approximate synonyms and alternate descriptions

Provider documentation does not always use the precise ICD-10-CM language. Coders encountering any of these terms in a clinical note can map them to M36.2, provided the hemophilia connection is established in the record. The AAPC Codify ICD-10-CM lookup tool lists these synonyms alongside the code for quick reference.

• Arthropathy in hemophilia
• Hemophilia joint disease
• Arthropathy due to factor VIII deficiency
• Arthropathy due to factor IX deficiency
• Arthropathy in factor deficiency
• Hemophilic joint disease
• Joint disease in hemophilia
• Hemarthrosis-related arthropathy (when chronic and classified as established arthropathy)

Keep the official inclusion term separate from these approximate synonyms. Hemarthrosis in hemophilic arthropathy is an inclusion term at M36.2, so a joint bleed in a patient with established arthropathy is coded here.

An isolated acute bleed in a patient with no documented arthropathy is a different clinical picture. Once hemophilic arthropathy is on the record, M25.0 cannot carry the hemarthrosis, because M25.0 excludes M36.2.

M36.2 in the M36 code category: related codes

M36.2 sits within the M36 category, which groups systemic disorders of connective tissue that are manifestations of diseases classified elsewhere. Reviewing the full M36 group helps coders select the correct subcategory when a patient’s arthropathy has a different systemic origin.

Neighboring categories in the same block cover other systemic connective tissue disorders, such as M32.9. The CDC ICD-10-CM tool provides hierarchical navigation by chapter and block.

Every code in this category is a manifestation code with its own Code first note, and none of them can be first-listed. The differentiator is the systemic cause the provider documents. A neoplasm-related arthropathy goes to M36.1, and an arthropathy from a hypersensitivity reaction goes to M36.4. Clear documentation of the underlying disease is what makes the selection defensible.

Coding guidelines and documentation for M36.2

Accurate documentation for ICD-10 Code M36.2 requires the clinical record to establish three things. The first is the presence of hemophilia, with the type and factor deficiency named. The second is evidence of joint disease resulting from hemarthrosis. The third is the joint or joints affected.

1. Confirm the hemophilia diagnosis in the record. The note must specify the type, whether that is hemophilia A (factor VIII deficiency), hemophilia B (factor IX deficiency), or another factor disorder. A vague reference to a bleeding disorder will not support the Code first sequence.
2. Identify the arthropathy as a manifestation of hemophilia. The provider must link the joint disease to repeated hemarthrosis. A general arthritis diagnosis without this connection does not support M36.2.
3. Select the correct underlying code. Map the factor deficiency to D66, D67, D68.0, or D68.1 based on the documented diagnosis.
4. Sequence the underlying disease code first, every time. Official Guideline I.A.13 makes this mandatory rather than situational. Report D66, D67, D68.0-, or D68.1 as the principal or first-listed diagnosis, then M36.2 as the additional code. M36.2 is never first-listed.
5. Document the affected joints. M36.2 does not require a joint-specific sub-code. The clinical record should still name the joints involved, for continuity of care and any surgical coding downstream.

Three pitfalls account for most M36.2 denials. The first is reporting M36.2 with no underlying disease code, which breaks the Code first instruction outright. The second is listing M36.2 as the principal diagnosis, a position no M36 code may occupy. The third is selecting M36.3 when the record names hemophilia as the cause.

Present on admission (POA) and CMS-HCC risk adjustment

POA reporting applies to inpatient admissions. For ICD-10 Code M36.2, the POA indicator reflects whether hemophilic arthropathy was present at the time of admission. Because the condition is chronic and progressive, it will usually carry a POA indicator of Y.

That holds when the patient is admitted for any condition and the arthropathy is documented as a comorbidity. Coders should not default to “U” (unknown) without querying the provider if documentation is unclear. HIPAA-compliant documentation workflows that capture comorbidity history at intake support accurate POA assignment.

CMS-HCC risk adjustment needs a separate check. Whether M36.2 maps to a Hierarchical Condition Category (HCC) affects a patient’s Risk Adjustment Factor (RAF) score. Model assignments are updated annually, so confirm the mapping for the applicable model year with the HCC ICD-10 Crosswalk tool before relying on it.

How Pabau supports diagnostic code management

Practices managing patients with hemophilic conditions face a specific documentation challenge. The Code first sequence for M36.2 has to hold on every encounter, not only on the visit where the diagnosis was made. A missed D66 on a follow-up claim generates the same denial as missing it on the first submission.

Pabau is practice management software with claims management built in. It supports the ICD-10 documentation and billing workflow behind pairings like M36.2 and its underlying disease code.

Structured digital intake forms capture the factor deficiency type at intake and pull it into the clinical record. Coders then have the detail they need at the point of billing, instead of chasing provider documentation afterward.

The patient record management features in Pabau let practices flag chronic conditions like hemophilia at the record level. That surfaces the underlying diagnosis code during billing, so M36.2 does not go out without its Code first partner ahead of it.

Practices comparing broader practice management software features usually want the biggest billing win first. Claims management joined to structured record capture is one of the highest-impact areas of revenue cycle management. That pays off fastest on code pairs where the companion code is mandatory, as it is for M36.2.

Keep the Code first sequence on every claim

Pabau helps practices flag hemophilia at the record level, capture factor deficiency type at intake, and keep the underlying disease code ahead of M36.2. See how Pabau supports billing accuracy across complex specialty workflows.

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Conclusion

ICD-10 Code M36.2 is a billable, specific code for hemophilic arthropathy, and it is a manifestation code. The Code first note under it makes the hemophilia diagnosis (D66, D67, D68.0-, or D68.1) a required companion, sequenced ahead of M36.2.

Submitting M36.2 on its own, or listing it first, is the most common billing error attached to this code. Either version will generate a denial in most payer edits.

Structured patient records and claims management in Pabau help practices hold that sequence on every encounter, turning a manual documentation check into a systematic one. To see how Pabau handles complex diagnostic code documentation, book a demo with the team.

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