Grading an Open Fracture With Gustilo-Anderson
The Gustilo-Anderson grade predicts how likely an open fracture is to become infected or end in amputation, and it sets which antibiotics and soft-tissue surgery the patient receives.
Key terminology
- Open fracture
- This fracture has a skin wound that connects the broken bone to the outside. Any wound near a fracture is treated as open until proven otherwise.
- Gustilo-Anderson
- This system grades open fractures from type I to type IIIC. It rates the soft-tissue injury and energy around the fracture.
- Zone of injury
- This region of damaged skin, muscle and periosteum surrounds a fracture. It is often far larger than the visible skin wound.
- Debridement
- This operation cuts away dead and contaminated tissue and washes out the wound. It is the step that reveals the true extent of an open fracture.
- Flap
- This operation moves living tissue with its own blood supply over exposed bone. Bone left bare without periosteum cannot heal or resist infection uncovered.
- Interobserver agreement
- This measures how often different examiners assign the same grade to the same case. Kappa (κ) corrects that agreement for chance.
Takeaways
- An open fracture is any fracture that communicates with the outside through a break in the skin. The tibia is the long bone most often fractured open because its anteromedial surface sits just under the skin. In a review of 39 studies, the tibia led with 1504 open fractures, far ahead of the femur at 347 (Zubair et al, Cureus 2024;16:e68925, PMID 39381475).
- Gustilo-Anderson grades the soft-tissue injury around the fracture. Type I is a clean wound under 1 cm. Type II is a wound over 1 cm without extensive soft-tissue damage. Type III is severe soft-tissue injury, a segmental fracture (bone broken in 2 places) or a traumatic amputation (Gustilo and Anderson, J Bone Joint Surg Am 1976;58:453-458, PMID 773941; Hammond et al, Bone Jt Open 2025;6:905-914, PMID 40774660).
- Type III splits into A, B and C by soft-tissue coverage and blood supply. IIIA still has adequate soft tissue to cover the bone despite extensive laceration. IIIB has periosteal stripping and exposed bone, usually with massive contamination, and typically needs a flap. IIIC is any open fracture with an arterial injury requiring repair (Gustilo et al, J Trauma 1984;24:742-746, PMID 6471139).
- Energy and mechanism outrank wound size when grading an open fracture. Gustilo placed high-energy trauma in type III irrespective of the size of the wound. A small puncture over a comminuted or segmental fracture from a crash is a type III injury. The zone of injury and periosteal stripping found at debridement matter far more than wound length (Gustilo et al, J Trauma 1984;24:742-746, PMID 6471139; Hammond et al, Bone Jt Open 2025;6:905-914, PMID 40774660).
- The final Gustilo-Anderson grade is assigned in the OR after debridement. The system was designed to be applied after irrigation and debridement, yet a grade is commonly given in the ED. Up to 12% of injuries may be misclassified at first look, particularly those with bone loss, and the error usually under-grades the injury (Hammond et al, Bone Jt Open 2025;6:905-914, PMID 40774660).
- Every open fracture gets early IV antibiotics, and type III adds gram-negative coverage. Early antibiotics were the strongest factor against infection in 1104 open fracture wounds. Gustilo found 77% of type III infections were gram-negative and advised adding an aminoglycoside to cefazolin (a first-generation cephalosporin). Some Danish regions give gram-negative coverage for every grade (Patzakis and Wilkins, Clin Orthop Relat Res 1989;243:36-40, PMID 2721073; Gustilo et al, J Trauma 1984;24:742-746, PMID 6471139; Krakau et al, Injury 2026;57:113415, PMID 42250466).
- Type IIIB and IIIC injuries have far higher infection and amputation rates than IIIA. In Gustilo's series of 87 type III fractures, infection ran 4% in IIIA, 52% in IIIB and 42% in IIIC. Amputation ran 0%, 16% and 42%. These are 1970s single-center figures, and modern rates are lower (Gustilo et al, J Trauma 1984;24:742-746, PMID 6471139).
- Surgeons agree on the Gustilo-Anderson grade only about 60% of the time. When 245 orthopedic surgeons graded 12 open tibia fractures from video, average agreement was 60% (range 42-94%), and residents and fellows matched at 59%. A separate kappa study found only moderate agreement, so treat outcome data reported by grade with caution (Brumback and Jones, J Bone Joint Surg Am 1994;76:1162-1166, PMID 8056796; Horn and Rettig, J Orthop Trauma 1993;7:357-360, PMID 8377047).