M23.4 – Loose body in knee

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

Non-billable header

ICD-10-CM code M23.4

Code: M23.4 (claims format: M234)
Description: Loose body in knee
Billable: No – use a more specific code below
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

Billable codes under M23.4

M23.4 is a header code and cannot be used on claims. Choose the most specific code:

M23.40 – Loose body in knee, unspecified kneeBillable
M23.41 – Loose body in knee, right kneeBillable
M23.42 – Loose body in knee, left kneeBillable

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):

joints of the spine (M40-M54)

Index terms for M23.4

Entries in the ICD-10-CM alphabetic index that lead to this code:

Related codes in M23

Frequently asked questions

What is ICD-10 code M23.4?

M23.4 is the ICD-10-CM code for loose body in knee, in the block M20-M25 (Other joint disorders).

Is M23.4 a billable code?

No. M23.4 is a header code with more specific child codes; report one of the billable codes listed above.

What category does M23.4 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.