M25.461 – Effusion, right knee

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

Billable code

ICD-10-CM code M25.461

Code: M25.461 (claims format: M25461)
Description: Effusion, 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: M25 › M25.4 › M25.46

Notes inherited from parent codes

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

M25 – Other joint disorder, not elsewhere classified

Excludes2 (not included here):

abnormality of gait and mobility (R26.-)
acquired deformities of limb (M20-M21)
calcification of bursa (M71.4-)
calcification of shoulder (joint) (M75.3)
calcification of tendon (M65.2-)
difficulty in walking (R26.2)
temporomandibular joint disorder (M26.6-)

M25.4 – Effusion of joint

Excludes1 (not coded here):

hydrarthrosis in yaws (A66.6)
intermittent hydrarthrosis (M12.4-)
other infective (teno)synovitis (M65.1-)

Block M20-M25

Excludes2 (not included here):

joints of the spine (M40-M54)

Related codes in M25.46

M25.462 – Effusion, left kneeBillable
M25.469 – Effusion, unspecified kneeBillable

Frequently asked questions

What is ICD-10 code M25.461?

M25.461 is the ICD-10-CM code for effusion, right knee, in the block M20-M25 (Other joint disorders).

Is M25.461 a billable code?

Yes. M25.461 is a billable/specific code that can be used to indicate a diagnosis for reimbursement purposes.

What category does M25.461 belong to?

It belongs to category M25 – Other joint disorder, not elsewhere classified.

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.