M86.629
BillableOther chronic osteomyelitis, unspecified humerus
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M86.629 an HCC code?
Yes. M86.629 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 M86.629
For M86.629 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 M86.629 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M86.629 is the ICD-10-CM diagnosis code for other chronic osteomyelitis, unspecified humerus. A chronic bone infection in the upper arm bone (humerus) where the specific side (left or right) is not specified or documented. M86.629 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering other osteopathies (m86-m90).
Under the CMS-HCC V28 risk adjustment model, M86.629 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, M86.629 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 laterality cannot be determined from the medical record. Because M86.629 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 M86.629 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when laterality cannot be determined from the medical record
- •Query the provider if possible to obtain laterality information for more specific coding
Clinical Significance
This code represents chronic osteomyelitis of the humerus when laterality is not specified. Despite the unspecified laterality, this condition represents a serious bone infection affecting upper arm function that requires intensive management and may result in significant functional impairment and disability.
Documentation Requirements
- ✓Documentation of chronic osteomyelitis duration (>6 weeks or recurrent)
- ✓Humerus bone involvement without laterality specification
- ✓Non-hematogenous etiology (contiguous or direct inoculation)
- ✓Imaging studies confirming bone infection in humerus
- ✓Laboratory evidence of infection or inflammatory response
- ✓Assessment of upper arm function and mobility
- ✓Treatment documentation including antibiotic therapy
- ✓Justification for unspecified laterality (bilateral involvement or unclear documentation)
Commonly Confused Codes
- •M86.621 — Other chronic osteomyelitis, right humerus (specific laterality)
- •M86.622 — Other chronic osteomyelitis, left humerus (specific laterality)
- •M86.529 — Other chronic hematogenous osteomyelitis, unspecified humerus (hematogenous)
- •M86.429 — Chronic osteomyelitis with draining sinus, unspecified humerus (has sinus)
- •M86.129 — Other acute osteomyelitis, unspecified humerus (acute phase)