Necrotizing Soft-Tissue Infections: An Orthopaedic Emergency

Adam Lee, MD; Addison May, MD, FACS, FCCM; William T. Obremskey, MD, MPH

Disclosures

J Am Acad Orthop Surg. 2019;27(5):e199-e206. 

In This Article

Presentation

Presenting features of necrotizing soft-tissues injuries can be vague and nondescriptive. There may be no features that initially distinguish necrotizing soft-tissue infections from nonnecrotizing soft-tissue infections. Close monitoring with interval examination is necessary because NSTIs can progress quickly, and seemingly benign presentations may become clearly defined over interval examinations (Figure 1, A and B).

Figure 1.

Photographs showing the (A) nonspecific erythema and (B) edema presentation of necrotizing fasciitis in a patient with no erythema or proximal edema on physical examination just 6 hours before.

A thorough history should be performed assessing for risk factors discussed earlier. In addition, potential sources of exposure and sites of inoculation should be elicited. In approximately 50% of cases, no site of entry is found. Exposure to household cohabitants infected with group A Streptococcus raises the risk of infection to 2000 times that of the general public, and such exposures should be determined.[6,22] Healthcare workers caring for patients with these highly virulent infections are at increased risk as well.[14] Pain out of proportion to examination is the most common finding and should raise one's suspicion for a more aggressive process.

Physical examination findings can be initially benign. The most common findings are erythema, edema/swelling/induration, and pain, although skin changes may not be present early.[7,10,18,23] Erythema can progress from red to purple/red as subcutaneous vessels are effaced and then to blue gray as superficial layers begin to necrose. As the disease progresses, the pain may abate because cutaneous nerves are obliterated by the infection resulting in anesthesia of the skin. Bullae may appear signifying tissue loss and are highly specific for an NSTI. (Figure 2) Finally, palpable crepitance in the tissues around the focus of infection, indicative of subcutaneous gas formation, is highly suggestive of an NSTI because of anaerobic bacteria. These so-called hard signs (ie, anesthesia, ecchymosis/bullae, gas in tissue) are present up to 44% of the time.[7,18,24] Importantly, the presence of gas in tissue that is identified with clinical examination or radiograph (Figure 2) is found only in infections from species that can grow under anaerobic conditions producing non–carbon dioxide gases, and these gases are present in less than 50% of cases. Up to 83% of patients present in clinical duress with signs consistent with a systemic inflammatory response syndrome, sepsis, or septic shock.[23]

Figure 2.

Radiograph showing gas in the soft tissue.

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