Wound & Hardware Infection - Trauma

Introduction
Overview wound and hardware infection can be a critical development in determining patient outcome Epidemiology incidence up to 16% infection rate following traumatic fracture risk factors host immunodeficiency extremes of age diabetes obesity alcohol or tobacco abuse steroid use malnutrition medications previous radiation vascular insufficiency Pathophysiology mechanisms seeding disruption of soft tissue envelope, blood vessels, and periosteum allow bacteria to avoid host defenses direct seeding of implant and/or anatomical structure hematogenous seeding biofilm formation dependent on exopolysaccharide glycocalyx
Presentation
History history of trauma must be detailed extent of soft tissue injury extent of bony injury previous or current hardware previous or current surgery at the same site history of previous skin or deep infections Symptoms pain at previous fracture site may indicate infected non-union fevers, chills, and night sweats may be present Physical exam inspection erythema, drainage, or purulence tenderness motion gross motion at fracture site is suggestive of non-union
Imaging
Radiographs recommended views biplanar images of afflicted area 45 degree orthogonal views can also be obtained to evaluate for union findings acute infection radiographs may be normal sub-acute and chronic infections peri-implant lucency can be seen involucrum reactive bone surrounding active infection sequestrum retained nidus of infected necrotic bone CT indications pre-operative planning MRI indications useful adjunct for diagnosis and delineating extent of disease to assess soft-tissue masses and fluid collections sensitivity and specificity 98% sensitive 78% specific WBC-labeled scans can help determine infection from other similar appearing etiologies helpful to detect bony infection in the setting of hardware hardware can cause metal artifact in an MRI making it difficult to assess for infection
Studies
Labs WBC may be normal in chronic or indolent infections erythrocyte sedimentation rate (ESR) may remain elevated for months following initial injury or surgery in absence of infection C-reactive protein (CRP) most predictive for postoperative infection in the first week after fracture fixation should decrease from a plateau after postoperative day 2 (after fixation of fractures) will increase further or fail to decrease if a hematoma or infection is present Cultures in-office cultures swabs or aspirations of wounds or sinus tracts are unreliable intraoperative deep cultures are most reliable method of isolated causative organisms multiple specimens from varying locations should be obtained
Treatment
Nonoperative chronic suppression with antibiotics indications risk of surgical treatment outweighs the benefit to the host immunosuppressed, elderly, etc. presence of an infected but incompletely healed fracture following internal fixation technique ESR and CRP levels used to assess adequacy of treatment outcomes 32% rate of chronic infected nonunion persisting or worsening despite suppression Operative surgical debridement indications any active infection technique hardware should be maintained if stability at risk with removal low-pressure irrigation with normal saline may be superior to other methods of irrigation thorough identification and debridement of infection key to success deep bony specimens should be obtained for culture as well as biopsy outcomes 71% success seen with debridement and antibiotics for early acute postoperative infection Risk factors for failure include intramedullary nail and open fracture