Orthopaedic Knowledge Update®: Musculoskeletal Infection 2 Print + Ebook (AAOS - American Academy of Orthopaedic Surgeons)

Section 6: Bone, Joint, and Soft-Tissue Infections

proposed classification of SSTIs was created and divided by severity into three classes, of which classes 2B and 3 often require surgery. 2 A study from 2020 reported that certain noninfectious dermatologic diseases, including pyoderma gangrenosum and desomorphine-induced deep ulceration, can mimic infections and should be included in the differential diagnosis. 3 A 2022 nonsystematic review reported that in addition to a course of antimi crobial therapy, surgical management includes incision and drainage and débridement for source control. 4 NECROTIZING SOFT-TISSUE INFECTIONS Risk Factors Although healthy individuals of any age without a clear portal of entry can be affected, there are several risk fac tors associated with NSTIs. 5-11 A 2022 study reported that patients presenting with SSTIs and any of these risk factors ( Table 1 ) should be assessed to confirm or exclude NSTI. Diabetes mellitus, in particular, increases the risk of NSTIs, regardless of anatomic location. 12 A retrospective study from 2019 reported that necrotizing ulcers can be observed when people who inject drugs practice skin popping and use drugs and adulterants with irritant or toxic properties. 13 Risk Factors Associated With Mortality in Patients With NSTIs NSTIs may lead to limb loss and in-hospital mortality in up to 25% of patients. 11 Mortality in patients with NSTIs increases with age (especially those older than 60 years), having multiple comorbidities, chronic liver disease, coro nary artery disease, chronic kidney disease, delayed sur gery (longer than 24 hours), intensive care unit admission, transfer from an outside hospital, bacteremia at initial presentation, clostridial infection, monomicrobial NSTI (versus polymicrobial), streptococcal toxic shock syndrome, elevated peripheral white blood cell count (>30,000/µL), thrombocytopenia, lactic acidosis, and elevated serum creatinine (greater than 2.0 mg/dL). 14-17 Histopathologic findings in determining risk of mortality (the fewer the neu trophils and the more the bacteria, the higher the mortality) may be used to predict outcomes; however, cohort size used in this single-center study was relatively small. 18 Of note, during the COVID-19 pandemic, a significant increase in complicated dental infections and related mortality was described in patients presenting with NSTIs, possibly due to the hypercoagulable state associated with COVID-19 pandemic and delay in seeking medical care. 13,19 Medicolegal Implications of NSTIs NSTIs are implicated in an array of medical malpractice lawsuits, including six reported on in 2020, involving finan cial compensation and even homicide. 20 A 2020 report found

Table 1

Risk Factors Associated With Necrotizing Soft-Tissue Infections Major penetrating trauma Gunshot wounds a , knife wounds a , as a result of natural disasters (earthquake a , hurricane b , tsunami b ) Blunt trauma Compound fractures a , crush injuries a , muscle contu sion, muscle sprain, muscle strain Skin breach Animal bite, insect bite, intramuscular injection a , minor laceration (including in seawater c or freshwater set tings b ), varicella lesion Genitointestinal mucosal breach Episiotomy, hemorrhoids, rectal fissures Recent surgery Gastrointestinal tract (including biliary tract) a , genito urinary tract, hip arthroplasty, liposuction d , neonatal circumcision Behavioral Alcohol use disorder, heavy exercise, ingestion of con taminated oysters c , injection drug use (especially use of black tar heroin and skin popping) a , malnutrition, poor hygiene, tobacco use Cardiovascular disease Chronic kidney disease, diabetes mellitus, gout, hyper tension, ischemic heart disease, obesity, peripheral vascular disease, stroke Colonic diseases Diverticulitis, inflammatory bowel disease, malignancy e Immunocompromising conditions Advanced HIV infection, chemotherapy, cirrhosis c , leukemia, lymphoproliferative disorders, neutropenia (including cyclic neutropenia e ), radiation therapy Peripartum conditions Childbirth, extremely low gestational age, gestational diabetes, pregnancy loss a , preterm delivery, retained placenta a , prolonged rupture of membranes a , intra uterine fetal demise a a These risk factors are associated with necrotizing soft-tissue infec tions (NSTIs) due to Clostridium perfringens . These can occur in victims of natural disasters (such as earthquakes) where there might be a delay in evacuation and treatment. b This risk factor is associated with NSTIs due to Aeromonas hydrophila . c These risk factors associated with NSTIs due to Vibrio vulnificus . d Not limited to abdominal liposuction. e These are risk factors associated with NSTIs due to Clostridium septicum .

Section 6: Bone, Joint, and Soft-Tissue Infections

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Orthopaedic Knowledge Update ® : Musculoskeletal Infection 2