M01.X59
BillableDirect infection of unspecified 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.X59 an HCC code?
Yes. M01.X59 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.X59
For M01.X59to 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.X59 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M01.X59 is the ICD-10-CM diagnosis code for direct infection of unspecified hip in infectious and parasitic diseases classified elsewhere. An infection in the hip joint (side not specified) caused by a disease classified elsewhere, such as tuberculosis or a parasitic infection. M01.X59 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.X59 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.X59 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 when hip laterality is not documented or when bilateral hip involvement is present. Because M01.X59 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.X59 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code when hip laterality is not documented or when bilateral hip involvement is present
- •Requires a secondary code to identify the underlying infectious or parasitic disease causing the joint infection
Clinical Significance
This code captures direct hip joint infection secondary to classified infectious or parasitic diseases when laterality is not documented, representing incomplete clinical documentation. Hip infections are particularly serious due to the joint's weight-bearing function and risk for rapid progression to systemic complications.
Documentation Requirements
- ✓Documentation of hip joint infection without laterality specification
- ✓Required underlying infectious or parasitic disease code as primary diagnosis
- ✓Evidence that hip infection is direct extension of classified disease
- ✓Clinical examination findings consistent with infectious hip arthropathy
- ✓Laboratory markers supporting infectious and inflammatory processes
- ✓Imaging studies demonstrating hip joint involvement and complications
- ✓Microbiological studies from joint aspiration when performed
- ✓Treatment protocol addressing both systemic infection and hip joint preservation
Commonly Confused Codes
- •M00.959 — Pyogenic arthritis, unspecified hip (bacterial infection not from classified disease)
- •M25.559 — Pain in unspecified hip (joint symptoms without infectious cause)
- •M01.X51 — Direct infection of right hip (when laterality is actually documented)
- •M01.X52 — Direct infection of left hip (when laterality is actually documented)