Antibiotic prophylaxis is a common practice across multiple surgical specialties; however, no relationship has been found between risk of surgical site infection and antibiotic prophylaxis in soft-tissue hand surgery. In a study of multistate commercial insurance claims, no difference in risk for postoperative surgical site infection was found between patients who had received antibiotic prophylaxis and those who had not.¹ A 2020 study of 312 Veterans Affairs patients undergoing carpal tunnel release also reported no difference in risk for surgical site infections in regard to prophylactic antibiotic use, or an operating room versus procedure room setting.²

Infection rates after soft-tissue hand surgery are consistently less than 1%. Building on previous literature, the authors of one study reported on 454,987 Medicare patients undergoing carpal tunnel release, reporting an infection rate of 0.32%.³ A number of other studies agree with these low infection rates in soft-tissue hand surgery, with or without antibiotic prophylaxis.⁴,⁵,⁶ Even in patients with prosthetic joints, according to a 2020 study there is no known risk of a prosthetic joint infection after clean hand surgery.⁷ It can be concluded that the rate of surgical site infection in soft-tissue hand surgery is low, without evidence to support the routine use of preoperative antibiotics.

Factors associated with an increased risk of surgical site infection after carpal tunnel release include male sex, age younger than 65 years, body mass index higher than 30 kg/m², tobacco and alcohol use, diabetes, inflammatory arthritis, vascular disease, chronic liver
disease, chronic kidney disease, chronic lung disease, and depression.³ In data from a 2019 study looking specifically at hemoglobin A1c levels in patients with diabetes undergoing primary open carpal tunnel release, elevated hemoglobin A1c levels higher than 7.8 were found to be associated with an increased risk of postoperative surgical site infection.⁸

In patients presenting to the emergency department with cellulitis, hand involvement is an independent risk factor for inpatient hospitalization.⁹ Community-acquired methicillin-resistant Staphylococcus aureus remains a common cause of hand soft-tissue infection, although polymicrobial infections are on the rise.¹⁰ One study recommended empiric coverage for community-acquired methicillin-resistant S aureus if local prevalence rates exceed 10% to 15%.¹¹ Unfortunately, multidrug-resistant methicillin-resistant S aureus is also being reported, with young age, intravenous drug use, and nosocomial infection as risk factors.¹²

Drainable fluid collections require intervention. Abscesses may be evaluated with ultrasonography, with a sensitivity as high as 96.7%. MRI may also be used with 89% sensitivity and 80% specificity for a soft-tissue abscess. In cases where ultrasonographic evaluation is difficult or access to MRI is limited, CT can be valuable in evaluating for an abscess.¹³ Early administration of antibiotics should be provided; antibiotics do not need to be held until decompression. Following surgical decompression, no difference has been demonstrated between different soaks or daily dressing change techniques.

The four Kanavel signs are used to clinically diagnose flexor tenosynovitis, but only 54% of patients with pyogenic flexor tenosynovitis may present with all of these signs.¹⁴ There are conflicting studies on which Kanavel signs are most sensitive or specific.¹⁵,¹⁶ Inflammatory markers such as white blood cell count, erythrocyte sedimentation rate, and C-reactive protein are used as adjuncts, but are not sensitive enough to use as a screening tool to rule out flexor tenosynovitis.¹⁷ Kanavel signs are not uniformly present in children and adolescents.

Patients presenting early (less than 24 hours of symptoms) or with mild symptoms may undergo a trial of intravenous antibiotic therapy alone.¹⁸ When nonsurgical management fails or a patient presents late or with significant findings, surgery is indicated. A systematic review reported excellent outcomes in 74% of patients treated with limited incisions and closed catheter irrigation compared with 26% of patients treated with open surgical drainage.¹⁹ Patients must be counseled on the possibility of repeat surgery, with another study showing a 14.2% rate of requiring additional surgical intervention.²⁰

The ideal route and duration of antibiotic administration in flexor tenosynovitis has not been determined.¹⁹ The most common pathogens identified are S aureus and beta-hemolytic Streptococcus.²¹ Worse outcomes are associated with older age, delay in antibiotic treatment, and medical comorbidities.¹⁵

Untreated septic arthritis erodes the articular cartilage. An inflamed joint needs to be evaluated appropriately and treated in a timely manner. Cases of atraumatic, inflamed joints have a wider differential diagnosis that includes crystalline arthropathy or rheumatoid disease. Joint-fluid analysis is helpful for diagnosis, although this can be difficult to obtain. One study reviewed 104 patients with inflamed wrists. Over a 2-year period, five patients had confirmed septic arthritis; of these, only two had undergone successful aspiration.²² According to a 2019 study, if a minimal amount of fluid is aspirated, the greatest diagnostic lead may come from a cell count and the percentage of polymorphonuclear leukocytes.¹⁸ After a septic joint is identified, surgical treatment, which may be open or arthroscopic, with irrigation or débridement is the standard of care. A course of intravenous antibiotics, possibly with a course of oral antibiotics to follow, is pursued. S aureus is the most common organism involved.

There are approximately 600 to 1,200 cases of necrotizing fasciitis yearly in the United States, and the extremities are most commonly affected.¹⁸ Mortality rates can vary from 5.4% to 11.1% and amputation rates are approximately 25% when the infection is based in the extremity.²³,²⁴ Independent risk factors for death include heart disease, white blood cell count greater than 30,000/µL, and creatinine level greater than 2 mg/dL.²³

Young, healthy individuals may have monomicrobial infection with group A beta-hemolytic Streptococcus. Vibrio species are also common. Patients with diabetes or other immunosuppressive conditions are more likely to have polymicrobial infections involving aerobic and anaerobic organisms.¹⁸

The initial diagnosis of necrotizing fasciitis is based on clinical findings in combination with imaging and laboratory results. The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score was developed to
help in diagnosis.²⁵ As shown in Table 1, an LRINEC score higher than 8 indicates greater than 75% chance of a patient having necrotizing fasciitis. In a study of atypical pathogens such as Vibrio, however, all mortality cases had a LRINEC score of less than 6.²⁶ In these cases, a LRINEC score of 2 or higher along with hemorrhagic bullae or blister skin lesions are important predictors of necrotizing fasciitis.²⁷ The most common risk factors for necrotizing fasciitis include intravenous drug use, smoking, trauma, and diabetes.²⁸ CT findings may show the presence of fascial air, edema, fluid tracking, lymphadenopathy, and subcutaneous edema. MRI findings are similar to those of nonnecrotizing soft-tissue infections. A definitive diagnosis can be made in the operating room with a fascial biopsy.