M66.1
Rupture of synovium
Not billable — category only FY2026 2025-10-01 → 2026-09-30
Exclusions 13 never code together
M66code
Excludes2
- rotator cuff syndrome (M75.1-)M75.1-
- rupture where an abnormal force is applied to normal tissue - see injury of tendon by body region
M00-M99chapter
Excludes2
- arthropathic psoriasis (L40.5-)L40.5-
- certain conditions originating in the perinatal period (P04-P96)P04-P96
- certain infectious and parasitic diseases (A00-B99)A00-B99
- compartment syndrome (traumatic) (T79.A-)T79.A-
- complications of pregnancy, childbirth and the puerperium (O00-O9A)O00-O9A
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)Q00-Q99
- endocrine, nutritional and metabolic diseases (E00-E88)E00-E88
- injury, poisoning and certain other consequences of external causes (S00-T88)S00-T88
- neoplasms (C00-D49)C00-D49
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)R00-R94
Excludes2 — not included here, but the patient may have both. Code both when documented.
Instructional notes 3
M66code
Includes
- rupture that occurs when a normal force is applied to tissues that are inferred to have less than normal strength
M66.1code
Inclusion terms
- Rupture of synovial cyst
M00-M99chapter
Notes
- Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition
Index entries leading here filed at null
No alphabetic index entry points at this code.
Alongside this code 5 same parent — M66
Subordinate codes 8
M66.10 Rupture of synovium, unspecified joint M66.11 Rupture of synovium, shoulder M66.12 Rupture of synovium, elbow M66.13 Rupture of synovium, wrist M66.14 Rupture of synovium, hand and fingers M66.15 Rupture of synovium, hip M66.17 Rupture of synovium, ankle, foot and toes M66.18 Rupture of synovium, other site
Additional references
AHA Coding Clinic® Licence required
Official coding advice for this code. Published by the American Hospital Association. Not included in this installation.