M02.859
BillableOther reactive arthropathies, unspecified hip
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M02.859 an HCC code?
Yes. M02.859 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 M02.859
For M02.859to 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 M02.859 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M02.859 is the ICD-10-CM diagnosis code for other reactive arthropathies, unspecified hip. Joint inflammation in the hip (side not specified) that develops as a reaction to an infection or other trigger elsewhere in the body. M02.859 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, M02.859 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, M02.859 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.
This unspecified code should only be used when laterality truly cannot be determined from the record. Because M02.859 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 M02.859 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This unspecified code should only be used when laterality truly cannot be determined from the record
- •Request clarification from the provider regarding which hip is affected to assign the appropriate specific code
Clinical Significance
This diagnosis represents reactive arthropathy affecting the hip when laterality is not specified in documentation. The unspecified nature may indicate bilateral hip involvement or incomplete clinical documentation, potentially affecting treatment planning and risk stratification.
Documentation Requirements
- ✓Clinical evidence of hip joint inflammation (pain, stiffness, reduced range of motion)
- ✓Documentation of reactive nature - inflammation secondary to remote infection
- ✓Confirmation that hip laterality is truly unspecified or bilateral involvement
- ✓Evidence ruling out direct septic arthritis or other infectious arthropathies
- ✓Documentation of triggering infection or infectious process (if identified)
- ✓Physical examination findings consistent with hip arthritis
- ✓Exclusion of other arthropathy types (rheumatoid, osteoarthritis, crystal arthropathy)
- ✓Assessment of functional impact on mobility and ambulation
Commonly Confused Codes
- •M02.851 — Other reactive arthropathies, right hip (when laterality is documented)
- •M02.852 — Other reactive arthropathies, left hip (when laterality is documented)
- •M00.059 — Staphylococcal arthritis, unspecified hip (infectious vs reactive)
- •M06.059 — Rheumatoid arthritis, unspecified hip (autoimmune vs reactive)
- •M25.559 — Pain in unspecified hip (symptom vs specific arthropathy diagnosis)