M25.66 – Stiffness of knee, not elsewhere classified

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

Non-billable header

ICD-10-CM code M25.66
Code
M25.66 (claims format: M2566)
Description
Stiffness of knee, not elsewhere classified
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
M25 › M25.6

Billable codes under M25.66

M25.66 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.

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-)

M25.6 – Stiffness of joint, not elsewhere classified

Excludes1 (not coded here):
  • ankylosis of joint (M24.6-)
  • contracture of joint (M24.5-)

Block M20-M25

Excludes2 (not included here):

Index terms for M25.66

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

Related codes in M25.6

Frequently asked questions

What is ICD-10 code M25.66?

M25.66 is the ICD-10-CM code for stiffness of knee, not elsewhere classified, in the block M20-M25 (Other joint disorders).

Is M25.66 a billable code?

No. M25.66 is a header code with more specific child codes; report one of the billable codes listed above.

What category does M25.66 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.