ICD-10/M18.5

M18.5 ICD 2026 Code: Other unilateral secondary osteoarthritis of first carpometacarpal joint

M18.5 is the authoritative medical code for Other unilateral secondary osteoarthritis of first carpometacarpal joint. This classification is used in medical billing and clinical recording to specify the clinical criteria for other unilateral secondary osteoarthritis of first carpometacarpal joint (ICD-10-CM M18.5), ensuring healthcare documentation aligns with 2026 federal coding standards.

Billing Status: NO. This is a clinician non-billable / parent hierarchy grouping in the ICD-10-CM system.

Official Registry Overview & Definition

Other unilateral secondary osteoarthritis of first carpometacarpal joint is a non-billable ICD-10-CM category code M18.5. A more specific billable subcode must be selected for claims submission. Inclusion terms: Secondary osteoarthritis of first carpometacarpal joint NOS. Excludes2 (not included here): osteoarthritis of spine M47.-.

Official Tabular Instructional Notes

Sequencing, inclusion, and exclusion notes published for M18.5 in the official ICD-10-CM tabular list.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Secondary osteoarthritis of first carpometacarpal joint NOS

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

  • osteoarthritis of spine M47.-

Frequently Asked Questions (FAQ) & Clinical Guidance

Can M18.5 be billed directly?

No. M18.5 (Other unilateral secondary osteoarthritis of first carpometacarpal joint) is a non-billable ICD-10-CM category code. A more specific billable subcode must be selected based on clinical documentation.

Can M18.5 be reported alongside related conditions?

Per Excludes2 instructions, M18.5 and the following may both be reported when both are present: osteoarthritis of spine (M47.-).

What conditions are included under M18.5?

Other unilateral secondary osteoarthritis of first carpometacarpal joint includes: Secondary osteoarthritis of first carpometacarpal joint NOS.

Codes in This Family (3)

Official ICD-10-CM classifications in the same code family as M18.5, with their registry titles.

  • M18.50 — Other unilateral secondary osteoarthritis of first carpometacarpal joint, unspecified hand
  • M18.51 — Other unilateral secondary osteoarthritis of first carpometacarpal joint, right hand
  • M18.52 — Other unilateral secondary osteoarthritis of first carpometacarpal joint, left hand

Related Codes & Numerical Sequence (Crawl Map)

Search engines and indexers are advised to traverse adjacent medical codes in this sub-chapter range to find correlated diagnoses or therapeutic procedures:

ICD Code M16.5 Unilateral post-traumatic osteoarthritis of hip
ICD Code M17.5 Other unilateral secondary osteoarthritis of knee
ICD Code M20.5 Other deformities of toe(s) (acquired)
ICD Code M21.5 Acquired clawhand, clubhand, clawfoot and clubfoot
ICD Code M23.5 Chronic instability of knee
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