M00.10
BillablePneumococcal arthritis, unspecified joint
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M00.10 an HCC code?
Yes. M00.10 maps to Bone/Joint/Muscle Infections/Necrosis under the CMS-HCC V28 risk adjustment model (and Bone/Joint/Muscle Infections/Necrosis under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. 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.
MEAT Criteria for M00.10
For M00.10to 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 M00.10 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M00.10 is the ICD-10-CM diagnosis code for pneumococcal arthritis, unspecified joint. A bacterial joint infection caused by Pneumococcus bacteria affecting a joint, where the specific joint location is not identified. M00.10 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, M00.10 maps to Bone/Joint/Muscle Infections/Necrosis (HCC 92) with a community, non-dual, aged base RAF weight of 0.209. Under the older V24 model, M00.10 mapped to the same category but with a base RAF weight of 0.482 — V28 recalibrated weights across the entire model. 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 this code only when the joint site is truly unspecified; more specific codes (M00.11-M00.19) should be used if joint location is documented. Because M00.10 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 M00.10 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
Clinical Significance
Septic arthritis caused by Streptococcus pneumoniae (pneumococcal) organisms is a medical emergency requiring urgent joint aspiration, intravenous antibiotics, and often surgical drainage to prevent permanent joint destruction. This unspecified-site code indicates the documentation does not identify which joint is affected, which may limit treatment planning specificity. The diagnosis carries meaningful risk adjustment weight reflecting the high resource utilization associated with managing acute bacterial joint infections.
Documentation Requirements
- ✓Provider documentation explicitly stating pneumococcal septic arthritis or pyogenic arthritis with identified causative organism
- ✓Synovial fluid analysis results (cell count, Gram stain, crystal analysis to rule out gout/pseudogout)
- ✓Culture and sensitivity results identifying the specific pneumococcal organism, or clinical rationale if culture-negative
- ✓Clinical signs and symptoms of joint infection (acute onset joint pain, swelling, warmth, erythema, fever, limited range of motion)
- ✓Query provider to specify the exact anatomical joint site and laterality for more precise code assignment
- ✓Treatment plan including antibiotic regimen, duration, and any surgical intervention (arthrocentesis, irrigation and debridement, arthroscopy)
Commonly Confused Codes
- •M00.2x (Other streptococcal arthritis) — Use M00.2x when the causative streptococcal organism is not Streptococcus pneumoniae; M00.1x is specifically for pneumococcal (Streptococcus pneumoniae) joint infections
- •M00.8x (Arthritis due to other bacteria) — Use M00.8x when the septic arthritis is caused by a non-streptococcal bacterium such as Staphylococcus aureus, Pseudomonas, or gram-negative rods
- •M00.0x (Staphylococcal arthritis) — Use M00.0x when culture identifies Staphylococcus species rather than Streptococcus pneumoniae
- •Site-specific M00 codes — Always assign the site-specific code when the affected joint is documented; unspecified joint codes should only be used when documentation truly lacks anatomical specificity