Table 3.
AO classification of open fractures
| Affected Tissue | Classification Score | Damage Severity |
|---|---|---|
| Skin | IO 1 | Minimal with skin breakage from inside out |
| IO 2 | Minimal with skin breakage from outside in (<5 cm) | |
| IO 3 | Moderate with skin breakage from outside in (>5 cm) | |
| IO 4 | Extensive with full-thickness contusion, abrasion, open degloving, and skin loss | |
| IO 5 | Extensive with severe degloving | |
| Muscle/Tendon | MT 1 | None |
| MT 2 | Minimal and local | |
| MT 3 | Moderate | |
| MT 4 | Extensive with muscle defect and tendon laceration | |
| MT 5 | Extensive with wide zone of injury and compartment syndrome | |
| Neurovasculature | NV 1 | None |
| NV 2 | Isolated | |
| NV 3 | Local | |
| NV 4 | Extensive with vascular injury | |
| NV 5 | Extensive with subtotal or total amputation |