M00.012
BillableStaphylococcal arthritis, left shoulder
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M00.012 an HCC code?
Yes. M00.012 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 M00.012
For M00.012to 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 M00.012 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M00.012 is the ICD-10-CM diagnosis code for staphylococcal arthritis, left shoulder. A bacterial infection of the left shoulder joint caused by Staphylococcus bacteria. M00.012 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, M00.012 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, M00.012 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.
Confirm left shoulder is documented as the infection site. Because M00.012 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 M00.012 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
Clinical Significance
Staphylococcal arthritis of the left shoulder is a serious bacterial joint infection (septic arthritis) requiring emergency treatment to prevent permanent joint damage. Staphylococcus is the most common causative organism in septic arthritis, and infection of the shoulder joint carries risks of cartilage destruction, osteomyelitis, and systemic sepsis. Accurate site-specific coding is essential for risk adjustment and reflects the high acuity and resource needs of this condition.
Documentation Requirements
- ✓Provider documentation identifying Staphylococcus as the causative organism (culture results, clinical diagnosis, or documented species)
- ✓Documentation of the affected joint with specific anatomical site
- ✓Laterality documented as left side
- ✓Clinical findings supporting joint infection (joint effusion, warmth, erythema, limited range of motion, fever)
- ✓Synovial fluid analysis results or culture and sensitivity reports when available
- ✓Treatment documentation (antibiotics, joint aspiration, surgical drainage/washout)
- ✓Assessment of whether the infection is acute or chronic, and whether it is a primary infection or secondary to another source
Commonly Confused Codes
- •M00.11x — Pneumococcal arthritis of same joint site; differs by causative organism (Pneumococcus vs. Staphylococcus)
- •M00.21x — Streptococcal arthritis of same joint site; differs by causative organism (Streptococcus vs. Staphylococcus)
- •M00.81x — Arthritis due to other bacteria at same joint site; use when organism is identified but not Staphylococcus
- •M00.9 — Pyogenic arthritis, unspecified; use only when causative organism cannot be identified