M23.91 – Unspecified internal derangement of right knee

ICD-10-CM 2027 diagnosis code · Other joint disorders

Billable code

ICD-10-CM code M23.91
Code
M23.91 (claims format: M2391)
Description
Unspecified internal derangement of right knee
Billable
Yes – valid for HIPAA-covered transactions
Valid for
Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter
13. Diseases of the musculoskeletal system and connective tissue (M00-M99)
Block
M20-M25 Other joint disorders
Parent codes
M23 › M23.9

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

M23 – Internal derangement of knee

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)

Block M20-M25

Excludes2 (not included here):

Related codes in M23.9

Frequently asked questions

What is ICD-10 code M23.91?

M23.91 is the ICD-10-CM code for unspecified internal derangement of right knee, in the block M20-M25 (Other joint disorders).

Is M23.91 a billable code?

Yes. M23.91 is a billable/specific code that can be used to indicate a diagnosis for reimbursement purposes.

What category does M23.91 belong to?

It belongs to category M23 – Internal derangement of knee.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.