Figure. Anteroposterior radiograph of the right ankle.
A 48-year-old woman presents for evaluation of her ankle. She had an open reduction and internal fixation of a right ankle fracture 2 months earlier. She has developed significant erythema, swelling, and warmth to the lateral ankle in the weeks leading up to her visit. The skin overlying the lateral plate is intact and no wound drainage is noted. An anteroposterior radiograph of the right ankle (Figure) shows an infected nonunion of the lateral malleolar fracture.
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This patient developed a surgical site infection that quickly spread to the deep hardware in the ankle. Once the subcutaneous layer becomes infected, the spread of infection to the hardware immediately adjacent is nearly unavoidable. Signs of a deep hardware infection include erythema, swelling, and drainage at the incision site along with the absence of radiographic signs of healing 2 months after surgery.1
Infection inhibits bone healing by dysregulating the bone formation (osteoblast) and bone resorbing (osteoclasts) cycle. Bacterial infection causes cell death of osteoblasts while enhancing osteoclastic mediated bone resorption. Radiographic signs of osteomyelitis include cortical thickening, periosteal bone formation, and new bone apposition.2
The most common causative agent of osteomyelitis is Staphylococcus aureus, which has an affinity for binding to hardware and forming a persistent biofilm on the surface of the hardware.3 The definitive treatment of deep hardware infection is removal of hardware and wound debridement. However, removal of hardware before the fracture has healed will likely result in displacement of the unstable fracture.1
In this case, bacterial suppression with oral antibiotics is indicated until the fracture is healed and amenable to removal of hardware. Serial radiographs and wound checks should be performed every 2 to 3 weeks if the wound remains stable and until there is radiographic signs of healing. Antibiotic suppression may not be indicated in cases where the skin over the hardware is compromised or the fracture fixation falls apart.3
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants.
- Steinmetz S, Wernly D, Moerenhout K, Trampuz A, Borens O. Infection after fracture fixation. EFORT Open Rev. 2019;4(7):468-475. doi:10.1302/2058-5241.4.180093
- Croes M, van der Wal BCH, Vogely HC. Impact of bacterial infections on onsteogenesis: evidence from in vivo studies. J Orthop Res. 2019;37(10):2067-2076. doi:10.1002/jor.24422.
- Croes M, van der Wal BCH, Vogely HC. Impact of bacterial infections on osteogenesis: evidence from in vivo studies. J Orthop Res. 2019;37(10):2067-2076. doi:10.1002/jor.24422