M21.861 — Other specified acquired deformities of right lower leg
Is M21.861 billable?
Yes, but M21.861 is an unspecified code. M21.861 is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, M21.861 is an unspecified or catch-all code. Payers apply additional scrutiny to unspecified codes and many deny them when the medical record supports a more specific option, so check the documentation before selecting M21.861 — the more specific alternatives are listed below.
M21.861 at a glance
| Code | M21.861 |
|---|---|
| Description | Other specified acquired deformities of right lower leg |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
Which MS-DRGs does M21.861 group to?
M21.861 sits in MDC 08 and helps define the logic of 3 MS-DRGs (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 564Other Musculoskeletal System and Connective Tissue Diagnoses with MCCmedical
- 565Other Musculoskeletal System and Connective Tissue Diagnoses with CCmedical
- 566Other Musculoskeletal System and Connective Tissue Diagnoses without CC/MCCmedical
How is M21.861 listed in the Alphabetic Index?
The Alphabetic Index lists these routes under M21.86, the nearest indexed parent of M21.861. Use them to find the family, then select the specific code.
- Deformity › limb › specified type NEC › lower leg
Excludes1 — never code together — inherited from M21
The conditions below can never be reported together with M21.861 on the same claim. An Excludes1 note means the two conditions cannot occur in the same patient, so reporting both is a coding error.
Excludes2 — not included here — inherited from Chapter 13
The conditions below are not part of M21.861, but a patient may have both at the same time. When documentation supports it, M21.861 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)
Excludes2 — not included here — inherited from M20-M25
The conditions below are not part of M21.861, but a patient may have both at the same time. When documentation supports it, M21.861 and the excluded code may both be reported.
- joints of the spine (M40-M54)
Excludes2 — not included here — inherited from M21
The conditions below are not part of M21.861, but a patient may have both at the same time. When documentation supports it, M21.861 and the excluded code may both be reported.
Excludes2 — not included here — inherited from M21.8
The conditions below are not part of M21.861, but a patient may have both at the same time. When documentation supports it, M21.861 and the excluded code may both be reported.
- coxa plana (M91.2)
How long has M21.861 existed?
M21.861 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.