M87.066 — Idiopathic aseptic necrosis of unspecified fibula
Is M87.066 billable?
Yes, but M87.066 will trip a Medicare edit. M87.066 is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, CMS lists M87.066 under Medicare Code Editor edit 20, “Unspecified code” — meaning a code specifying laterality (right, left or bilateral) exists in the same family. On an inpatient claim this triggers the edit, because CMS holds that there are very limited circumstances in which laterality cannot be documented.
M87.066 at a glance
| Code | M87.066 |
|---|---|
| Description | Idiopathic aseptic necrosis of unspecified fibula |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
What Medicare edits apply to M87.066?
The Medicare Code Editor screens inpatient claims before they are grouped. These edits name M87.066 directly.
A code specifying laterality (right, left or bilateral) exists in the same family. CMS holds that there are very limited circumstances in which laterality cannot be documented.
Which MS-DRGs does M87.066 group to?
M87.066 sits in MDC 08 and helps define the logic of 2 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 553Bone Diseases and Arthropathies with MCCmedical
- 554Bone Diseases and Arthropathies without MCCmedical
As a secondary diagnosis, M87.066 is a complication or comorbidity (CC), which can move a stay into a higher-paying DRG.
How is M87.066 listed in the Alphabetic Index?
The Alphabetic Index lists these routes under M87.06, the nearest indexed parent of M87.066. Use them to find the family, then select the specific code.
- Osteonecrosis › idiopathic aseptic › fibula
- Osteonecrosis › idiopathic aseptic › tibia
Excludes1 — never code together — inherited from M86-M90
The conditions below can never be reported together with M87.066 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
- postprocedural osteopathies (M96.-)
Excludes1 — never code together — inherited from M87
The conditions below can never be reported together with M87.066 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Use additional code — inherited from M87
Report an additional code alongside M87.066 to fully describe the condition. M87.066 is sequenced first.
- code to identify major osseous defect, if applicable (M89.7-)
Excludes2 — not included here — inherited from Chapter 13
The conditions below are not part of M87.066, but a patient may have both at the same time. When documentation supports it, M87.066 and the excluded code may both be reported.
- arthropathic psoriasis (L40.5-)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- compartment syndrome (traumatic) (T79.A-)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
How long has M87.066 existed?
M87.066 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.