A recent report from the Lower Extremity Assessment Project (LEAP), a multi-institutional prospective observational study of 545 patients with limb-threatening lower extremity trauma with 2-year follow-up at eight Level-1 trauma centers, documented that wound infection (34 %) was the most common complication in the primary amputation group, and that nonunion (31.5 %) and wound infection (23.2 %) were the most common complications in the limb salvage group. Furthermore, the late amputation group had the highest complication rate (68 %), mostly due to wound infection [10]. When traumatic wound infections occur, it is recommended to initiate early empiric broad-spectrum antibiotic therapy to cover methicillin-resistant S. aureus (MRSA) and all other potential pathogens, obtain wound cultures, and then tailor definitive antimicrobial therapy once the culture results return. In addition, the wound may require surgical debridement to provide adequate source control.

SSIs are one of the most common SSTIs that occur in orthopedic and trauma care. SSIs are defined as “superficial incisional” or “deep incisional” SSI based on the depth of the infection as defined by the Centers for Disease Control (CDC) and the National Healthcare Safety Network (NHSN) (Table 25.3).

It has recently been determined that scores commonly used to predict SSI in other types of surgery [National Nosocomial Infection Surveillance System (NNIS) and Study on the Efficacy of Nosocomial Infection Control (SENIC) scores] are not predictive of SSI after orthopedic fracture surgery [11]. A new score [RIOTS Composite Score includes fractures classification AO type C3 or Sanders type 4, 2 points; BMI < 30 kg/m², 1 point; ASA class ≥ 3, 1 point] was proposed for SSI prediction in orthopedic fracture surgery that incorporates fracture classification, American Society of Anesthesiologists classification, and body mass index with area under the ROC curve of 0.75, significantly higher than NNIS and SENIC scores.

A Cochrane Database systematic review of patients undergoing surgery for proximal femoral and other closed long bone fractures (data from 8447 participants in 23 studies) documented that single dose antibiotic prophylaxis significantly reduced deep incisional SSI (risk ratio 0.40, 95 % CI 0.24–0.67), superficial incisional SSI, urinary infections, and respiratory tract infections. Multiple dose antibiotic prophylaxis had an effect of similar size on deep incisional SSI. Therefore, appropriate antibiotic prophylaxis should be used in all patients undergoing surgical management of hip or other closed long bone fractures [20].

The recent publication of the “Clinical practice guidelines for antimicrobial prophylaxis in surgery” by the American Society of Health-System Pharmacists (ASHP), Infectious Diseases Society of America (IDSA), Surgical Infection Society (SIS), and Society for Healthcare Epidemiology of America (SHEA) provides evidence-based national recommendations [21].

Antibiotics reduce the incidence of early infections in open fractures of the limbs, confirmed by a Cochrane Database systematic review of 913 participants in 7 studies. The use of antibiotics had a protective effect against early infection compared with no antibiotics or placebo (relative risk 0.41 [95 % confidence interval (CI) 0.27–0.63]; absolute risk reduction 0.08 (95 % CI 0.04–0.12); number needed to treat (NNT) 13 (95 % CI 8–25). There were insufficient data in the included studies to evaluate other outcomes [22]. The Surgical Infection Society evidence-based guidelines for prophylactic antibiotic use in open fractures recommend the use of a short course of first-generation cephalosporins, begun as soon as possible after injury, in addition to modern orthopedic fracture wound management (Table 25.6) [23]. Open fracture grade (Gustilo) and the degree of associated soft-tissue injury are independent determinants of infection risk. A recent single-institution review of patients with Gustilo IIIB tibial fractures (n = 52) determined that nosocomial bacterial pathogens (Enterococci, Pseudomonas, Enterobacter, and MRSA) were responsible for deep tissue infections, and advocated for tailoring antimicrobial prophylaxis against nosocomial organisms at the time of definitive wound closure [24].

NSTIs are aggressive soft tissue infections that cause widespread necrosis, and can include necrotizing cellulitis, fasciitis, and myositis/myonecrosis [25, 26]. Establishing the diagnosis of NSTI can be the main challenge in treating patients with NSTI, and knowledge of all available tools is the key for early and accurate diagnosis (Table 25.7) [27]. There have been a number of recent advances in the definition, pathogenesis, diagnostic criteria, and treatment of necrotizing soft tissue infections [28, 29].

Patients with NSTIs require prompt aggressive surgical debridement, appropriate intravenous antibiotics, and intensive support. Despite aggressive treatment, their mortality and morbidity rates remain high, with some series reporting mortality rates of 25–35 % [30]. A high index of suspicion should be used in conjunction with laboratory and imaging studies to establish the diagnosis as rapidly as possible. Successful treatment requires early, aggressive surgical debridement of all necrotic tissue, appropriate broad-spectrum systemic antibiotic therapy, and supportive care (fluid resuscitation, organ and critical care support) to maintain oxygenation and tissue perfusion. Delayed definitive debridement remains the single most important risk factor for death.

A recent single-institution series of 166 patients documented that the overall mortality rate was 16.9 % and limb loss occurred in 26 % of patients with extremity involvement [31]. Independent predictors of mortality included white blood cell count greater than 30,000 × 10³/μL, creatinine level greater than 2 mg/dL (176.8 μmol/L), and heart disease at hospital admission. Independent predictors of limb loss included heart disease and shock (systolic blood pressure <90 mmHg) at hospital admission. Clostridial infection was an independent predictor for both limb loss (odds ratio, 3.9 [95 % confidence interval, 1.1–12.8]) and mortality (odds ratio, 4.1 [95 % confidence interval, 1.3–12.3]) and was highly associated with intravenous drug use and a high rate of leukocytosis on hospital admission.

A 30-day postoperative mortality risk calculator for NSTI was recently developed using the National Surgery Quality Improvement Project (NSQIP) which identified seven independent variables that correlated with mortality: age older than 60 years (odds ratio [OR] = 2.5; 95 % CI 1.7–3.6), functional status (partially dependent: OR = 1.6; 95 % CI 1.0–2.7; totally dependent: OR = 2.3; 95 % CI 1.4–3.8), requiring dialysis (OR = 1.9; 95 % CI 1.2–3.1), American Society of Anesthesiologists class 4 or higher (OR = 3.6; 95 % CI 2.3–5.6), emergent surgery (OR = 1.6; 95 % CI 1.0–2.3), septic shock (OR = 2.4; 95 % CI 1.6–3.6), and low platelet count (<50 K/μL: OR = 3.5; 95 % CI 1.6–7.4; <150 K/μL but >50 K/μL: OR = 1.9; 95 % CI 1.2–2.9). The receiver operating characteristic area was 0.85 (95 % CI 0.82–0.87), which indicated a strong predictive model that can aid physicians in the decision-making process [32].