FY2027 ICD-10-CM reference
M66: Spontaneous rupture of synovium and tendon
By the HCC Buddy Coding Team
The official ICD-10-CM descriptor is Spontaneous rupture of synovium and tendon. The FY2027 annual edition starts October 1, 2026. Check the edition that applies to the encounter or inpatient discharge, including any April update.
Nonbillable heading. Verified against the official FY2027 order file.
CMS-HCC V28
Not applicable to this nonbillable heading
CMS-HCC V24
Not applicable to this nonbillable heading
ESRD
Not applicable to this nonbillable heading
PACE
Not applicable to this nonbillable heading
RxHCC
Not applicable to this nonbillable heading
HHS-HCC
Not applicable to this nonbillable heading
More specific FY2027 codes
- M66.0: Rupture of popliteal cystBillable code
- M66.1: Rupture of synoviumNonbillable heading
- M66.2: Spontaneous rupture of extensor tendonsNonbillable heading
- M66.3: Spontaneous rupture of flexor tendonsNonbillable heading
- M66.8: Spontaneous rupture of other tendonsNonbillable heading
- M66.9: Spontaneous rupture of unspecified tendonBillable code
FY2027 Tabular instructions
Instructions below include applicable chapter, section and parent-code notes. Each note identifies where it appears in the official source.
Instructional note
Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition
Source: M00-M99 (chapter, inherited).
Excludes2
arthropathic psoriasis (L40.5-)
Source: M00-M99 (chapter, inherited).
Excludes2
certain conditions originating in the perinatal period (P04-P96)
Source: M00-M99 (chapter, inherited).
Excludes2
certain infectious and parasitic diseases (A00-B99)
Source: M00-M99 (chapter, inherited).
Excludes2
compartment syndrome (traumatic) (T79.A-)
Source: M00-M99 (chapter, inherited).
Excludes2
complications of pregnancy, childbirth and the puerperium (O00-O9A)
Source: M00-M99 (chapter, inherited).
Excludes2
congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
Source: M00-M99 (chapter, inherited).
Excludes2
endocrine, nutritional and metabolic diseases (E00-E88)
Source: M00-M99 (chapter, inherited).
Excludes2
injury, poisoning and certain other consequences of external causes (S00-T88)
Source: M00-M99 (chapter, inherited).
Excludes2
neoplasms (C00-D49)
Source: M00-M99 (chapter, inherited).
Excludes2
symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Source: M00-M99 (chapter, inherited).
Includes
rupture that occurs when a normal force is applied to tissues that are inferred to have less than normal strength
Source: M66 (category, direct).
Excludes2
rotator cuff syndrome (M75.1-)
Source: M66 (category, direct).
Excludes2
rupture where an abnormal force is applied to normal tissue - see injury of tendon by body region
Source: M66 (category, direct).
Compare the FY2027 additions, removals and billable-status changes
What does M66 mean in FY2027?
The official ICD-10-CM descriptor is Spontaneous rupture of synovium and tendon. The FY2027 annual edition starts October 1, 2026. Check the edition that applies to the encounter or inpatient discharge, including any April update.
Is M66 billable in FY2027?
The FY2027 order file marks M66 as a nonbillable heading. Select a complete billable child code.
Does M66 map to an HCC?
Risk-model mapping is not applicable to this nonbillable heading. Check a complete billable child code.
Source: CMS FY2027 ICD-10-CM order file. Payment model: CMS CY 2027 Rate Announcement. Read the FY2027 Official Guidelines.
Review the FY2026 April edition