M89.771 (Major osseous defect, right ankle and foot) compared with M89.779 (Major osseous defect, unspecified ankle and foot), from the official CMS tabular data. M89.771 and M89.779 code the same condition on opposite sides.
Same condition; these differ only in which side is documented.
These codes share a category and title and differ only in the side affected. The documentation decides which applies, and a bilateral code is reported only where the code set provides one.
Source: ICD-10-CM tabular list (laterality variant derived from the code title)
Same condition, opposite side. M89.771 and M89.779 name the same condition on opposite sides of the body.
Same category and title, differing only in which side is affected — the documentation decides which one applies, and a bilateral code is reported only where the code set provides one.
| M89.771Major osseous defect, right ankle and foot | M89.779Major osseous defect, unspecified ankle and foot | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | M00-M99 — Diseases of the Musculoskeletal System and Connective Tissue (M00-M99) | M00-M99 — Diseases of the Musculoskeletal System and Connective Tissue (M00-M99) |
| Definition | Major osseous defect, right ankle and foot is a billable ICD-10-CM diagnosis code (M89.771). | Major osseous defect, unspecified ankle and foot is a billable ICD-10-CM diagnosis code (M89.779). |
| Code first | underlying disease, if known, such as: aseptic necrosis of bone (M87.-) | underlying disease, if known, such as: aseptic necrosis of bone (M87.-) |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources