Question 1

What is ICD-10 code M13.871?

Accepted Answer

M13.871 is the ICD-10-CM diagnosis code for other specified arthritis, right ankle and foot. A type of arthritis affecting the right ankle and foot that doesn't fit into other specific arthritis categories. M13.871 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering inflammatory polyarthropathies (m05-m14).

M13.871 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

This code specifies the right side; do not use if left ankle/foot or bilateral involvement is documented.

Question 2

Is M13.871 an HCC code?

Accepted Answer

No. M13.871 is a billable ICD-10-CM code but does not map to any payment HCC category under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can still be reported on Medicare Advantage encounter data submissions, but it does not contribute to the beneficiary's Risk Adjustment Factor (RAF) score and therefore does not affect the risk-adjusted capitation payment to the plan. V28 reached 100% phase-in for payment year 2026.

Question 3

Is M13.871 billable?

Accepted Answer

Yes. M13.871 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. M13.871 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Question 4

What is the V28 vs V24 difference for M13.871?

Accepted Answer

M13.871 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards M13.871 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

Question 5

What should coders know when reporting M13.871?

Accepted Answer

This code specifies the right side; do not use if left ankle/foot or bilateral involvement is documented Document which specific joints in the ankle/foot are affected for clinical clarity, though this code captures the general area

M13.871

Is M13.871 an HCC code?

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