M23
ICD-10Non-billable categoryInternal derangement of knee
Official ICD-10-CM descriptor (FY2026)
Internal derangement of knee
M23 is a category heading, not a billable code. CMS does not accept it on a claim; report one of the more specific codes beneath it.
Excludes1
Not coded here. An Excludes1 code should never be reported at the same time as the code above it.
- ankylosis (M24.66)
- deformity of knee (M21.-)
- osteochondritis dissecans (M93.2)
Excludes2
Not included here. The condition is not part of this code, but a patient may have both, and both codes may be reported together.
- 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)
More specific codes under M23
- M23.0Cystic meniscuscategory
- M23.2Derangement of meniscus due to old tear or injurycategory
- M23.3Other meniscus derangementscategory
- M23.4Loose body in kneecategory
- M23.5Chronic instability of kneecategory
- M23.6Other spontaneous disruption of ligament(s) of kneecategory
- M23.8Other internal derangements of kneecategory
- M23.9Unspecified internal derangement of kneecategory
Where this code sits
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ICD-10-CM FY2026. Centers for Medicare & Medicaid Services (CMS) / National Center for Health Statistics (NCHS), “2026 ICD-10-CM Code Descriptions in Tabular Order” (icd10cm_order_2026.txt). Download the original file from cms.gov. Public domain (US Government work). Descriptors, billable flags and instructional notes on this page are reproduced from that file without modification. Krasyn adds no clinical guidance.