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M00.869 ICD-10-CM Code: Arthritis due to other bacteria, unspecified knee

M00.869 maps to CMS-HCC V28 92 (RAF 0.479). 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) / Infectious arthropathies (M00-M02)

M00.869

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

Arthritis due to other bacteria, unspecified knee

Bacterial infection causing inflammation and swelling in the knee joint when the specific side (left or right) is not specified or documented.

Buddy the Bee presenting code insight

Buddy Insight

Bacterial arthritis of unspecified knee indicates a serious infection of this critical weight-bearing joint, though documentation lacks laterality specification.

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
M00.8Arthritis and polyarthritis due to other bacteria
M00.86Arthritis due to other bacteria, knee
M00.869Arthritis due to other bacteria, unspecified knee

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for M00.869 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for M00.869 in this effective period.

Related Child Codes

Official
M00.861Arthritis due to other bacteria, right knee
M00.862Arthritis due to other bacteria, left knee

Includes

Official

ICD-10-CM does not list Includes notes for M00.869 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for M00.869 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for M00.869 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for M00.869 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for M00.869 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Evidence of 'other bacteria' causing knee infection
Documentation of knee joint involvement without laterality
Bacterial culture or microbiological confirmation
Signs and symptoms of infectious arthritis

MEAT Support

HCC Buddy guidance
Evidence of 'other bacteria' causing knee infection
Documentation of knee joint involvement without laterality
Bacterial culture or microbiological confirmation
Signs and symptoms of infectious arthritis

Audit Caution

HCC Buddy guidance
Using unspecified when laterality documented elsewhere
Not attempting laterality clarification for this serious condition
Confusing with chronic knee conditions
Coding as non-infectious when bacterial cause present

Common Mistakes

HCC Buddy guidance
M00.861/M00.862 — Same condition with specific laterality
M00069 — Streptococcal arthritis of unspecified knee (different organism)
M00019 — Staphylococcal arthritis of unspecified knee (specific bacteria)
M06.869 — Other rheumatoid arthritis of unspecified knee (autoimmune)

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 M00.869 an HCC code?

Yes. M00.869 (Arthritis due to other bacteria, unspecified knee) 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: M00.869 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
M00.869
Description
Arthritis due to other bacteria, unspecified knee
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 M00.869 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for M00.869

For M00.869 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 M00.869 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

M00.869 is the ICD-10-CM diagnosis code for arthritis due to other bacteria, unspecified knee. Bacterial infection causing inflammation and swelling in the knee joint when the specific side (left or right) is not specified or documented. M00.869 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, M00.869 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, M00.869 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.

Use only when laterality is truly unspecified or bilateral involvement is not separately coded. Because M00.869 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 M00.869 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Use only when laterality is truly unspecified or bilateral involvement is not separately coded
  • •Attempt to clarify laterality with the provider to assign a more specific code

Clinical Significance

Bacterial arthritis of unspecified knee indicates a serious infection of this critical weight-bearing joint, though documentation lacks laterality specification. This condition requires urgent treatment to prevent cartilage destruction and permanent mobility impairment.

Documentation Requirements

  • ✓Evidence of 'other bacteria' causing knee infection
  • ✓Documentation of knee joint involvement without laterality
  • ✓Bacterial culture or microbiological confirmation
  • ✓Signs and symptoms of infectious arthritis
  • ✓Treatment with systemic antibiotics
  • ✓Assessment of knee mobility and weight-bearing status
  • ✓Laboratory evidence of infection and inflammation
  • ✓Attempt to clarify laterality for complete documentation

Commonly Confused Codes

  • •M00.861/M00.862: Same condition with specific laterality
  • •M00069: Streptococcal arthritis of unspecified knee (different organism)
  • •M00019: Staphylococcal arthritis of unspecified knee (specific bacteria)
  • •M06.869: Other rheumatoid arthritis of unspecified knee (autoimmune)
  • •M17.10: Unilateral primary osteoarthritis of unspecified knee (degenerative)

Child Codes

M00.861Arthritis due to other bacteria, right knee
HCC 92
M00.862Arthritis due to other bacteria, left knee
HCC 92
M00.869Arthritis due to other bacteria, unspecified knee
HCC 92

Code Hierarchy

└M00Pyogenic arthritis└M00.8Arthritis and polyarthritis due to other bacteria└M00.86Arthritis due to other bacteria, knee└M00.869Arthritis due to other bacteria, unspecified knee
└M00.869Arthritis due to other bacteria, unspecified knee

Because M00.869 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.

M00.869 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 M00.869 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.

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