Excludes1 pair
M43.5- vs M99-
M43.5 and M99 are not coded together. ICD-10-CM declares them mutually exclusive with an Excludes1 note — the two conditions are not expected to occur together, so exactly one of them is normally correct for a given encounter. The Official Guidelines carve out one exception: if the two conditions are clearly unrelated to each other, both may be reported.
The official note, declared on M43.5
biomechanical lesions NEC (M99.-)
M43.5
Other recurrent vertebral dislocation
Not billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M40-M43
Indexed under
- Dislocation › recurrent › vertebra
M99
Biomechanical lesions, not elsewhere classified
Not billable
- Chapter 13
- Diseases of the musculoskeletal system and connective tissue
- Section
- M99
Excludes1 is not always absolute: where two conditions covered by the note are genuinely unrelated, CMS guidance permits reporting both. Document the reasoning rather than assuming it. More on Excludes1 vs Excludes2 · FY2027