M25.661 ICD-10-CM Code: Stiffness of right knee, not elsewhere classified
Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.
Inpatient Payment Groups (MS-DRG)
MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43.0 (FY2026), Appendix B.
- MS-DRG 555 — SIGNS AND SYMPTOMS OF MUSCULOSKELETAL SYSTEM AND CONNECTIVE TISSUE WITH MCC (MDC 08)
- MS-DRG 556 — SIGNS AND SYMPTOMS OF MUSCULOSKELETAL SYSTEM AND CONNECTIVE TISSUE WITHOUT MCC (MDC 08)
A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.
Code Set: Valid FY2026 and FY2027. FY2026 took effect October 1, 2025.
Official Registry Overview & Definition
Official Tabular Instructional Notes
Sequencing, inclusion, and exclusion notes published for M25.661 in the official ICD-10-CM tabular list.
Excludes1 — Not Coded Here
Conditions that can never be reported with this code; the two are mutually exclusive.
- ankylosis of joint (M24.6-)
- contracture of joint (M24.5-)
Excludes2 — Not Included Here
Conditions not covered by this code, but which may be reported alongside it when both are present.
- 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-)
- joints of the spine (M40-M54)
Nearest Codes in This Family
Official ICD-10-CM classifications closest to M25.661 in its code family, with their registry titles.
- M25.65 — Stiffness of hip, not elsewhere classified
- M25.651 — Stiffness of right hip, not elsewhere classified
- M25.652 — Stiffness of left hip, not elsewhere classified
- M25.659 — Stiffness of unspecified hip, not elsewhere classified
- M25.66 — Stiffness of knee, not elsewhere classified
- M25.662 — Stiffness of left knee, not elsewhere classified
- M25.669 — Stiffness of unspecified knee, not elsewhere classified
- M25.67 — Stiffness of ankle and foot, not elsewhere classified
- M25.671 — Stiffness of right ankle, not elsewhere classified
- M25.672 — Stiffness of left ankle, not elsewhere classified