Hand infections, which include cellulitis, paronychia and felons, flexor tenosynovitis, and deep palmar space infections, are frequently encountered by primary care and emergency physicians in addition to orthopedic surgeons. Early diagnosis and treatment is key to optimal outcomes.
Epidemiology
Occur from direct inoculation from penetrating trauma, or from untreated infections elsewhere in the hand that spread contiguously into the deep spaces of the hand.1
Pathoanatomy
Deep spaces of the hand include the thenar, midpalmar, Parona’s quadrilateral, dorsal subaponeurotic, and interdigital subfascial web space (Figure 47.1 and Table 47.1)1,3,4,5,6
Mechanism of injury
Infection can occur from inoculation such as penetrating trauma or bites.1
Untreated infections in surrounding regions may spread through adjacent spread.
More rarely hematogenous spread may occur to any of the palmar spaces.7 Knowledge of anatomy of these regions and their boundaries can help identify and predict spread of deep infection.
Untreated flexor tenosynovitis can cause infection within the palmar spaces
The radial bursa is contiguous with the flexor pollicis longus (FPL) tendon sheath while the ulnar bursa communicates with the small finger flexor tendon sheath.
Approximately 50% to 80% of people have communicating radial and ulnar bursae. This occurs via multiple variations of connections
between the index, middle, ring, and small finger tendon sheaths, as well as the FPL tendon sheath with the ulnar and radial bursa.7,8 Infections involving the thumb flexor tendon or small finger flexor tendon can thus result in a “horseshoe abscess.”7,8
Infection of the index finger flexor tendon sheath can spread to the thenar space, as this sheath is the volar boundary of the thenar space.7
Infection involving the thenar space in the interval between the adductor pollicis and first dorsal interossei muscles can cause a “pantaloon” effect.7
Contiguous spread of flexor tenosynovitis can continue proximally to involve Parona’s space. The communication that can exist between the radial and ulnar bursa occurs via Parona’s space, and thus can extend to the carpal tunnel.9
Controversy exists whether involvement of the carpal tunnel is from communicating spread or through rupture of the bursa.9
Parona’s space can also be involved through spread from an infection within the radiocarpal joint and invasion through the volar joint capsule.6
Penetrating trauma
Infected palmar blisters or skin fissures
Collar button abscesses occur in the interdigital subfascial space, typically from spread from an infected palmar blister or skin fissure (see Chapter 46).7 Adherent fascia and palmar skin force the
abscess to extend dorsally into the web space.7 Additionally, the interdigital web space is contiguous with the dorsal subcutaneous tissue between fingers.3
Microbiology
Over 90% of infections are bacterial in origin.11
Staphylococcus aureus and Streptococcus species are the most commonly implicated bacteria, with Staphylococcus the principal organism in 50% to 80% of infections.7,12
S. aureus tends to cause a suppurative infection that peaks in 3 to 6 days.12
Staphylococcus epidermidis infections tend to be more superficial.12
Methicillin-resistant S. aureus (MRSA) infections are becoming increasingly frequent, with an incidence of 34% to 73% in all hand infections.5,13
Risk factors for MRSA infections include patients with diabetes or an immunocompromised state, as well as a history of prior antibiotic use. Additionally, risk factors include those patients living in close spaces such as contact sports, military recruits, day cares, prisoners, or homeless patients.
Nosocomial MRSA acquisition can occur from prolonged hospital stays, in particular in an intensive care unit.1
Depending on the mechanism of injury, different bacteria may be present (Table 47.2).
Trauma is the most common etiology of hand infections followed by a laceration or puncture wound.14
Industrial injuries or those within the home typically are a single microbial infection with a Gram-positive organism.7
Bite wounds, farm injuries, and infections in IV drug users as well as diabetics are often polymicrobial and involve Gram-negative and anaerobic species in addition to Gram-positive organisms.1
 FIGURE 47.1 Anatomy of deep palmar spaces. Cross-section of hand demonstrates thenar, midpalmar, and hypothenar spaces. From Abrams RA, Botte MJ. Hand infections : treatment recommendations for specific types. J Am Acad Orthop Surg. 1996;4(4):219-230. |
TABLE 47.1 Anatomy of Deep Palmar Spaces | ||||||||||||||||
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TABLE 47.2 Antibiotic Recommendations for Specific Clinical Scenario | |||||||||||||||||||||||
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Inquire about a history of trauma or inoculating injury.
May have history of other hand infections that have spread to involve the deep spaces including antecedent cellulitis, felon, paronychia, flexor tenosynovitis, septic arthritis, or osteomyelitis
Inquire about recent surgery or IV drug use.
May present with fever, pain, malaise
Risk factors for the development of hand infections include diabetes mellitus and patients who are immunocompromised or on immunosuppressant drugs.7
The classic signs of flexor tenosynovitis may be present if the deep space infection results from spread from advanced flexor tenosynovitis (see Chapter 44).
Kanavel signs—fusiform swelling, tenderness over the flexor tendon sheath, finger resting in a flexed position, and pain with passive extension of the finger16Related posts:
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