M01.X51
BillableDirect infection of right hip in infectious and parasitic diseases classified elsewhere
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M01.X51 an HCC code?
Yes. M01.X51 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 M01.X51
For M01.X51to 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 M01.X51 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M01.X51 is the ICD-10-CM diagnosis code for direct infection of right hip in infectious and parasitic diseases classified elsewhere. An infection in the right hip joint caused by a disease classified elsewhere, such as tuberculosis or a parasitic infection. M01.X51 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, M01.X51 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, M01.X51 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 code indicates the hip joint infection is secondary to another infectious or parasitic disease. Because M01.X51 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 M01.X51 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code indicates the hip joint infection is secondary to another infectious or parasitic disease
- •Always include a secondary diagnosis code to identify the underlying infectious condition
Clinical Significance
Direct infection of the right hip joint secondary to classified infectious or parasitic diseases represents a severe condition affecting weight-bearing capacity and mobility. Hip infections carry high risk for osteonecrosis, joint destruction, and permanent disability, requiring aggressive treatment and close monitoring.
Documentation Requirements
- ✓Clear documentation of right hip joint infection
- ✓Primary diagnosis code for underlying infectious or parasitic disease
- ✓Evidence of direct relationship between systemic infection and hip involvement
- ✓Physical examination documenting hip pain, limited range of motion, and functional impairment
- ✓Laboratory studies supporting infectious process (WBC, ESR, CRP, blood cultures)
- ✓Imaging studies confirming hip joint involvement (X-ray, MRI, CT, bone scan)
- ✓Joint aspiration results with synovial fluid analysis when performed
- ✓Treatment plan addressing both underlying disease and hip-specific interventions
Commonly Confused Codes
- •M00.951 — Pyogenic arthritis, right hip (bacterial infection not from classified disease)
- •M25.551 — Pain in right hip (joint pain without infectious etiology)
- •M01.X52 — Direct infection of left hip in infectious diseases classified elsewhere
- •M87.051 — Idiopathic aseptic necrosis of right femoral head (non-infectious hip necrosis)