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M23

Non-billable

Internal derangement of knee

M23 is the ICD-10-CM code for Internal derangement of knee. It is a non-billable category code — use a more specific child code such as M23.0 for billing.

Status
Header (non-billable)
Chapter
M00-M99
Subcodes
8
Edition
FY2026

M00-M99 Diseases of the musculoskeletal system and connective tissue

What this means — in plain language

MedlinePlus · NIH

Your knee joint is made up of bone, cartilage, ligaments and fluid. Muscles and tendons help the knee joint move. When any of these structures is hurt or diseased, you have knee problems. Knee problems can cause pain and difficulty walking. Knee problems are very common, and they occur in people of all ages. Knee problems can interfere with many things, from participation in sports to simply getting up from a chair…

Read more about Knee Injuries and Disorders at MedlinePlus ↗

Source: U.S. National Library of Medicine (MedlinePlus). Informational only — not medical advice.

Excludes1 — not coded here

  • •ankylosis (M24.66)
  • •deformity of knee (M21.-)
  • •osteochondritis dissecans (M93.2)

Excludes2 — not included here

  • •current injury - see injury of knee and lower leg (S80-S89)
  • •recurrent dislocation or subluxation of joints (M24.4)
  • •recurrent dislocation or subluxation of patella (M22.0-M22.1)

Frequently asked questions

What is ICD-10 code M23?
M23 is the ICD-10-CM code for "Internal derangement of knee". It falls under M00-M99 Diseases of the musculoskeletal system and connective tissue.
Is M23 a billable code?
No — M23 is a non-billable header code. Use a more specific child code (such as M23.0) for billing.
What are the subcodes of M23?
M23 has 8 more specific child codes, including M23.0, M23.2, M23.3.
What is excluded from M23?
Excludes1 (not coded here): ankylosis (M24.66); deformity of knee (M21.-); osteochondritis dissecans (M93.2).

Source: CMS ICD-10-CM FY2026. For informational purposes only — not medical advice. See our medical disclaimer.

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