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M91.1 vs M96

M91.1 (Juvenile osteochondrosis of head of femur [Legg-Calvé-Perthes]) compared with M96 (Intraoperative and postprocedural complications and disorders of musculoskeletal system, not elsewhere classified), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.

Relationship

Conflict

Excludes1 conflict

M91.1
Juvenile osteochondrosis of head of femur [Legg-Calvé-Perthes]
↔
M96
Intraoperative and postprocedural complications and disorders of musculoskeletal system, not elsewhere classified

Not coded here — these two are mutually exclusive.

“postprocedural chondropathies (M96.-)”

An Excludes1 note means the two conditions cannot occur together, so the pair should not be reported for the same encounter. The sole exception is when the conditions are documented as unrelated to each other.

Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a

Can these codes be reported together?

No — do not report together. M91.1 carries an Excludes1 note covering M96: “postprocedural chondropathies (M96.-)”

Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Side by side

M91.1Juvenile osteochondrosis of head of femur [Legg-Calvé-Perthes]M96Intraoperative and postprocedural complications and disorders of musculoskeletal system, not elsewhere classified
Billing statusNon-billable header

Report instead: M91.10, M91.11, M91.12

Non-billable header

Report instead: M96.0, M96.1, M96.2, M96.3, M96.4

ClassificationM00-M99 — Diseases of the Musculoskeletal System and Connective Tissue (M00-M99)M00-M99 — Diseases of the Musculoskeletal System and Connective Tissue (M00-M99)
DefinitionJuvenile osteochondrosis of head of femur [Legg-Calvé-Perthes] is a non-billable ICD-10-CM category code (M91.1).Intraoperative and postprocedural complications and disorders of musculoskeletal system, not elsewhere classified is a non-billable ICD-10-CM category code (M96).
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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources