Infections of the Hand
Jose Ma D Bautista, MD
Associate Professor in Orthopedics
College of Manila
University of the Philippines - Manila
Infections of the hand are common and may cause significant morbidity. Most if not all of us have had some form of infection involving the hand, whether it be from a nail fold or an abscess. This module provides an overview of the common infectious conditions involving the hand and the principles of treatment. After going through this module, the student should be able to:
Define the different types of infection.
Discuss the pathogenesis of infections of the hand.
Describe the anatomic features of the hand that differentiate infections of the hand from other parts of the body.
Discuss the principles of treatment of these infections.
Infections involving the hand may cause significant morbidity, including loss of work, dysfunction and even loss of the hand or a part of it. Treatment should be prompt and properly guided by an understanding of the principles of treatment. Knowledge of the peculiarities of the anatomy of the hand is a minimum if adequate management is to be provided. An awareness of the prevailing microbiologic landscape is important in choosing the appropriate antibiotic. Management usually (but not always) requires some form of incision and drainage. In sum, the general principles of treatment of these infections involve prompt recognition, appropriate antimicrobial coverage, prompt and adequate surgical intervention when warranted, elevation and edema control and prompt mobilization as soon as tolerated.
GENERAL TYPES OF INFECTION
Cellulitis can occur anywhere there is skin and is defined as an infection of the subcutaneous tissue. It is often diffuse and presents with all the signs of symptoms of inflammation – calor, dolor, rubor, tumor and functio laesa. Lymphangitis or an inflammation of the lymphatic channels may accompany this type of infection and is seen as red streaks travelling proximally from the area of infection, following the course of the lymphatic channels.
What characterizes this type of infection is the absence of a collection of purulent material or pus. The most common causative agent is Staphylococcus aureus followed by b-hemolytic Streptococcus, the latter being associated with the more severe forms with lymphangitis. There is however a rise in the incidence of infections caused by Methicillin-resistant Staphylococcus aureus (MRSA) worldwide. As there is no collection of pus, treatment is nonsurgical, ideally with intravenous antimicrobials. However, a failure of the infection to subside after 48 hours of IV therapy may signal a progression involving formation of a collection of pus and a more serious infection.
Failure to respond to first line treatment may also signal more serious conditions such as staphylococcal scalded skin syndrome, a condition more common in children, or necrotizing fasciitis. The former is characterized by exfoliation of the skin and signs of sepsis while the latter is characterized by a watery discharge often described a “dish-water like.” Both these conditions are grave and the latter is often life-threatening. A high index of suspicion for these infections are important when initial IV therapy is not working.
Signs of cellulitis may overlie a deeper infection such as an abscess or septic arthritis. It is very important that underlying infections be ruled out before a diagnosis of cellulitis be made. The choice of antibiotic is usually a broad spectrum antibiotic or in areas with high incidence of MRSA, vancomycin or clindamycin.
An abscess is an infection where there is purulent discharge which may or may not be enclosed in a well-defined cavity. It is usually caused by a puncture or other break in the skin that allows inoculation of the causative agent. While it is tempting to start empiric antibiotics immediately, it is important that a specimen be collected for cultures prior to the initiation of IV therapy. This can be done by an aspiration of the abscess to obtain material to be sent to the laboratory. Incision and drainage is a mainstay of treatment for this infection, together with an empiric antibiotic, usually broad spectrum and covering most common organisms, to be later shifted to culture-guided therapy. Multi-organism infections are common among diabetics and anaerobic agents should be considered in diabetics and IV drug users.
Paronychia is an infection of the nail fold. A disruption of the seal between the nail plate and the nail fold allows entry of bacteria beneath the eponychial fold. Common causes of bacterial seeding are manicures, nail biting and forceful removal of hang nails. The most common infecting organism is S. aureus.
Acute paronychia presents as redness, swelling and tenderness of the nail fold, later on progressing to abscess formation which may spread from the nail fold to underneath the nail plate. The abscess may spread to include the entire nail fold (runaround abscess). Most paronychias present when there is already an abscess and the mainstay of treatment is surgical decompression. The eponychium is released and lifted from the nail and the space underneath washed out. If the perionychium is involved the incision should extend to where the abscess on the lateral aspect of the nail is. If the infection involves the undersurface of the nail plate, part of or the entire nail should be removed to prevent inadequate decompression and ischemia of the germinal matrix. The latter could affect growth of the nail.
When the eponychium is chronically rounded and indurated, it is most likely because of a chronic paronychia and brings with it a different set of clinical challenges.
Acute paronychia with infection involving the perionychium and part of the eponychium.
- from Green’s Operative Hand Surgery, 6th ed.
The pulp of the finger has a distinctive anatomy. The skin in this region is held firmly via septa to the distal phalanx. This anchorage aids in sensation and pinch. However, the septations also form multiple compartments that are poorly compliant and are prone to increased pressure and subsequent vascular compromise. Felons are infections affecting the pulp and present with intense throbbing pain, swelling and redness of the pulp. A history of trauma is usual and the most common organism is S. aureus. The closed space causes an increase in pressure accounting for the severe pain and the possible necrosis of the pulp from poor blood flow. When seen early, that is before the onset of an abscess, antibiotics are the mainstay of treatment. Once an abscess forms, the treatment should involve an incision over the point of maximal tenderness and a probing to evacuate all pockets of abscess that may be present because of the multiple septa, being careful to avoid the proximal end of the distal phalanx so as not to inoculate the flexor sheath. The wound is then left open with the insertion of a wick to allow drainage. Antibiotics should start empirically and be shifted once culture results are in.
Illustration of felon and pulp anatomy.
Herpetic whitlow is a viral infection which is commonly mistaken for a bacterial one. Depending on where the characteristic lesions are, they are frequently misdiagnosed as felons or paronychias. But if this infection is treated like bacterial ones, the it can result in severe complications. This infection may occur in both children and adults. In children the thumb or finger may become inoculated by sucking if the mouth and the surrounding area have herpetic gingivostomatitis. In adults, it has a decidedly higher prevalence among health professionals who come into contact with saliva from patients who are actively shedding the virus. The causative agent is the herpes simplex virus type 1.
Initial presenting symptoms include a prodrome of pain or tingling and numbness of the finger, followed by erythema and mild swelling and an intense pain that is disproportionate to the appearance of the affected digit. After several days, 1- to 2-mm clear vesicles appear and begin to enlarge and coalesce, eventually forming bullae. The fluid which is initially clear begins to become turbid and seemingly purulent, causing this to be mistaken for bacterial in origin. The lesions eventually resolve but these continue to shedding the virus for around 3 weeks after the onset of the symptoms, until epithelialization of the lesions is complete. Diagnosis is by viral cultures, Tzanck smear or antibody titer testing. As this infection is self-limiting, the crucial step is arriving at a correct diagnosis and avoiding the proliferation and spread of the infection to others. In fact patients are advised to wear gloves until lesions heal. Treatment is mostly symptomatic although antivirals are often prescribed which may decrease pain but does not change the course of the infection significantly. Superimposed bacterial infection may be treated with antibiotics and in select cases, a careful debridement.
Herpetic whitlow in a child.
- from Green’s Operative Hand Surgery, 6th ed.
Pyogenic flexor tenosynovitis
The flexor tendons of the thumb and fingers are enclosed within fibro-osseus tunnels starting at the level of the distal palm to the insertion of the flexor digitorum profundus. The pulleys that make up these tunnels are important in optimizing biomechanical forces that flex the joints of the fingers. Inside the tunnels, the tendons are bathed in synovial fluid secreted by the synovium that lines the inside of the pulleys. The fluid is nutrition-rich and is an excellent medium for bacterial growth. A bacterial infection of the flexor tendons within this sheath is called a pyogenic flexor tenosynovitis.
Acute infections present with Kanavel’s signs: 1. Flexed attitude of the finger, 2. Tenderness over the course of the flexor sheath, 3. Fusiform swelling, and 4. Severe pain on passive extension. Not all signs may be present especially early in the course. There is usually a history of penetrating injury. Aside from the history and physical examination, CBC should be done to check for leukocytosis and to monitor response to treatment; radiographs are also helpful to rule out missed fractures, osteomyelitis and retained foreign bodies. Causative agents are usually S. aureus and Strep. species. Occasionally, mycobacterial infections may occur but the course is more indolent.
Infections of the sheaths of the thumb and the small finger may present with contiguous spread to deep spaces. The sheath of the thumb is continuous with the radial bursa and that of the small finger with the ulnar bursa, both of which communicate proximally with each other through the space of Parona at the level of the wrist and distal forearm, just superficial to the pronator quadratus. This infection that involves both bursae via Parona’s space is called a “horseshoe abscess.”
Although they are rarely seen on the first day of onset, early infections may respond to IV antibiotics, elevation and splinting. If signs and symptoms do not improve after 24 hours, then surgery in necessary. Surgery involves limited incisions at the proximal and distal ends of the sheath and irrigation with saline using a pediatric feeding tube or an angiocatheter inserted into the proximal end and allowing the fluid to flow out the distal incision. Antibiotics should be empiric initially and later on culture-guided. Delays in treatment of this infection are disastrous as tendons are easily denatured by bacterial enzymes and acidic pH, resulting in scar tissue which will not glide within the sheaths even after the infection has been eradicated.
Deep space infections
The hand has three potential spaces bound by unyielding anatomic structures. In the palm the space is divided into three by two septa (midpalmar septum and hypothenar septum), the thenar space, midpalmar space and the hypothenar space. Each of these spaces are distinct from each other and are deep enough that access to them involves potential injury to numerous important structures in the hand. Infections involving these spaces present as pain, fullness and erythema of the hand corresponding to the location of these spaces. While the fullness and swelling are primarily from the palmar side, significant swelling may be present dorsally owing to the more expansile nature of the dorsal skin. A fourth potential space, the Parona’s space was discussed earlier and is usually part of a contiguous infection from the radial and ulnar bursae.
Once diagnosed, treatment is surgical, debridement of the spaces being necessary to avoid complications from scarring such as contractures. A specimen for culture may be aspirated prior to starting antibiotics or collected during surgical decompression. Antibiotics should cover S. aureus and other gram-positive organisms.
Illustration from Green’s Operative Hand Surgery, 6th ed.
An infection of the web space is called a collar-button abscess, so named because its dumbbell shape resembles the collar buttons of the early 20th century. It usually develops from skin fissure in the palmar aspect, a penetrating injury or an extension from the finger. The origin of the infection is volar and the volar pocket of purulent material which is constrained by the tight palmar fascia is unable to expand in this space and consequently forces its way dorsally via the space just distal to the neurovascular bifurcation. The accumulation of a dorsal pocket of purulence and the volar pocket with a narrow connection between them give rise to it name.
This condition presents with pain and fullness of the webspace and the fingers adjacent to the webspace adopt an abducted position away from the involved webspace. Causative agents are similar to other hand infections and treatment involves drainage of both pockets of purulence. The dorsal swelling is commonly more prominent than the volar fullness and this may cause some surgeons to overlook the primary source of the infection. Once both pockets are evacuated and irrigated, they are left open with a wick, to heal by secondary intention.
Human bite injuries of the hand may be truly bite-induced or may be from so-called clenched fist injuries. Bite-induced injuries are obvious in terms of history and presentation and may occur anywhere in the hand that is accessible to the human mouth. Clenched fist injuries however, are commonly missed injuries. They are breaks in the skin over the metacarpophalangeal joint sustained when a clenched fist strikes a tooth or several teeth in the course of a fistfight. The wound may be very small causing the both patient and attending doctor to miss or dismiss it. These latter injuries are prone to serious complications because of the delay in recognition and management.
In clenched fist injuries, the injury is sustained with the metacarpophalangeal joint in flexion and the tooth may penetrate not just the skin but also the extensor tendon and the dorsal joint capsule. This wound may appear trivial and superficial if it is examined with the joint in extension, where the extensor tendon retracts proximally and the injury is no longer visible through the wound, causing the examiner to miss both the tendon injury and the possible penetration into the joint. Because of this, it is important to examine these wounds with the hand clenched in a fist.
Workups should include CBC, baseline CRP and ESR and radiographs. Clenched fist injuries may have concomitant fractures (so-called divot type) of the metacarpal head or may have a retained foreign body such as a tooth.
Both types of human bites invariable develop infections if left untreated. These wounds require surgical debridement and irrigation; arthrotomy should be performed if the injury has penetrated into the joint. Because of the flora of the mouth, a broad spectrum antibiotic to cover the most common skin pathogens should be started. In addition, anaerobic coverage should also be started for Eikenella corrodens, a facultative anaerobe and gram negative rod that is frequently associated with these wounds, usually a high dose penicillin.
An example of a clenched fist injury or “fight bite” at left. Center and right pictures are those of the surgical incisions necessary to adequately explore and debride clenched fist injuries.
- pictures from Green’s Operative Hand Surgery, 6th ed.
Animal bites are common causes of infections of the hand although this is not exclusive to the hand. Dogs, cats and rodents are usual culprits. Tetanus immunization status of the patient and rabies immunization of the animal should be ascertained when possible. Wounds need thorough washing during the acute phase and if infection ensues, surgery and IV antibiotics. Any wound that from an animal bite that presents as puncture wounds together with intense pain needs to be surgically enlarged under local anesthesia to enable adequate irrigation. All wounds regardless of size should be left open. Antibiotics should cover the usual S. aureus and Streptococcus and anaerobes. Pasteurella multocida is a common pathogen isolated in dogs’ and cats’ mouths and need to be covered for.
Septic arthritis, osteomyelitis and gas gangrene may occur in the hand just like elsewhere in the body. Diagnosis and management of these conditions are similar to when they occur elsewhere, taking into consideration the anatomy of the hand.
General Antibiotic Recommendations for Common Infections.
Adapted from Green’s Operative Hand Surgery, 7th ed.
1. Wolfe, SW, et al. Green’s Operative Hand Surgery, 6th ed.
2. Wolfe, SW, et al. Green’s Operative Hand Surgery, 7th ed.
3. Abrams RA & Botte MJ. Hand Infections: Treatment Recommendations for Specific Types. J Amer Acad Orthop Surg, 4(4), 1996.