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ICD-10-CM 2027 diagnosis code

M23Internal derangement of knee

Not billable — use a more specific code

M23 is a header code, so it can't be reported by itself. Choose one of the 8 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About M23

M23 is the ICD-10-CM diagnosis code for internal derangement of knee. It belongs to block M20-M25 (other joint disorders) and chapter 13 (diseases of the musculoskeletal system and connective tissue). It is a header code, so it can't be reported by itself; one of its 8 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: M23.0 (meniscus), M23.2 (injury), M23.3 (derangements), M23.4 (knee), M23.5 (knee), M23.6 (knee), M23.8 (knee) and M23.9 (knee).

Don't report M23 together with the conditions in its Excludes1 note: ankylosis (M24.66), deformity of knee (M21.-) and osteochondritis dissecans (M93.2).

The conditions in its Excludes2 note aren't part of M23, but may be coded alongside it if the patient has both: current injury - see injury of knee and lower leg (S80-S89), recurrent dislocation or subluxation of joints (M24.4) and recurrent dislocation or subluxation of patella (M22.0-M22.1).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under M23

Coding notes

Excludes1Not coded here — never report together with this code
  • ankylosis (M24.66)
  • deformity of knee (M21.-)
  • osteochondritis dissecans (M93.2)
Excludes2Not included here — may be reported together if both conditions exist
  • 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)

Notes that apply from higher levels

Instructions written at a parent level also apply to M23.

Broader instructions also apply from M20-M25 Other joint disorders and Chapter 13: Diseases of the musculoskeletal system and connective tissue.

Codes whose notes reference M23

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about M23

Is M23 billable?

No. M23 is a header code. Report one of its more specific subcodes instead.