M05.66 – Rheumatoid arthritis of knee with involvement of other organs and systems
ICD-10-CM 2027 diagnosis code · Inflammatory polyarthropathies
- Code
M05.66(claims format:M0566)- Description
- Rheumatoid arthritis of knee with involvement of other organs and systems
- Short description
- Rheumatoid arthritis of knee w involv of organs and systems
- 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
- M05-M14 Inflammatory polyarthropathies
- Parent codes
- M05 › M05.6
Billable codes under M05.66
M05.66 is a header code and cannot be used on claims. Choose the most specific code:
Notes inherited from parent codes
Instructional notes at a category or block level apply to every code below it.
M05 – Rheumatoid arthritis with rheumatoid factor
Index terms for M05.66
Entries in the ICD-10-CM alphabetic index that lead to this code:
Related codes in M05.6
- M05.60 – Rheumatoid arthritis of unspecified site with involvement of other organs and systemsBillable
- M05.61 – Rheumatoid arthritis of shoulder with involvement of other organs and systemsHeader
- M05.62 – Rheumatoid arthritis of elbow with involvement of other organs and systemsHeader
- M05.63 – Rheumatoid arthritis of wrist with involvement of other organs and systemsHeader
- M05.64 – Rheumatoid arthritis of hand with involvement of other organs and systemsHeader
- M05.65 – Rheumatoid arthritis of hip with involvement of other organs and systemsHeader
- M05.67 – Rheumatoid arthritis of ankle and foot with involvement of other organs and systemsHeader
- M05.69 – Rheumatoid arthritis of multiple sites with involvement of other organs and systemsBillable
Frequently asked questions
What is ICD-10 code M05.66?
M05.66 is the ICD-10-CM code for rheumatoid arthritis of knee with involvement of other organs and systems, in the block M05-M14 (Inflammatory polyarthropathies).
Is M05.66 a billable code?
No. M05.66 is a header code with more specific child codes; report one of the billable codes listed above.
What category does M05.66 belong to?
It belongs to category M05 – Rheumatoid arthritis with rheumatoid factor.
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.