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Before the introduction of antibiotics, infections of the hand often led to prolonged morbidity, severe deformity, amputation, and even death. Kanavel’s classic article in 1939 on the pathways of purulent infection within the anatomic compartments of the hand opened the modern era of treatment for these problems. Although injuries in the industrial workplace are less prevalent than in Kanavel’s time, wounds of the hand still account for a large percentage of hand infections. A high incidence of hand infections is also associated with societal problems, such as intravenous injection of drugs with contaminated needles, wounds inflicted with various weapons in gang-related incidents, and complications of treatment with immunosuppressive agents. Human and animal bites may also have severe consequences.

The evaluation of a hand wound must include the duration of time since the injury, the contamination likely at the site of injury, and the severity of the wound. After the initial evaluation of the patient’s neurovascular and musculoskeletal status, the examiner must make a decision about further evaluation and treatment. It is generally better to err on the side of caution and thoroughly inspect the wound under surgical control in the operating room. Regional, intravenous, or general anesthesia is induced. In a fresh wound, exsanguination is performed with an elastic bandage; if the wound is already infected, elevating the limb for 2 minutes reduces the risk of forcing the inflammation deeper into normal tissue. Hemostasis is obtained with an upper arm pneumatic or an Esmarch forearm tourniquet.

Foreign material and devitalized tissue are debrided, and the wound is thoroughly irrigated. Pulsed lavage with 3 L or more of saline solution significantly reduces bacterial contamination. Reducing the bacterial population below 1 million organisms/mm3 allows the normal immune defenses to control contaminants. After debridement, exposed tendons, vessels, nerves, and joints should be protected, but wound closure should be delayed. Fine-meshed gauze impregnated with petroleum and 3% bismuth tribromophenate and then gauze dampened with saline solution provides a non- stick, antibacterial, and moist dressing to protect the exposed tissues. The hand is overwrapped in gauze and immobilized with a splint and elevated, which is extremely effective in halting infection. This open treatment followed by repeat debridement at 3 to 5 days and with delayed primary closure produces excellent results. Some smaller wounds are left open and treated by whirlpool baths daily with damp to dry dressings changed twice daily until granulation and epithelialization gradually closes the wound from the inside out preventing anaerobic bacteria from being trapped in a prematurely closed, subsequently anoxic wound.
The same approach to postoperative care is appropriate after incision and drainage of abscesses. In the immediate postoperative period, the wrist is generally immobilized in dorsiflexion, the metacarpophalangeal joints in 30 to 40 degrees of flexion, and the proximal interphalangeal joints in relative extension. A bulky dressing provides pressure to reduce edema and capillary drainage to extract exudate. These measures minimize the likelihood of joint contractures due to immobility.

Cellulitis And Epidermal Abscess
If possible, cultures should be obtained before beginning antibiotic therapy for any hand infection. Gram- positive cocci are responsible for most abscesses, particularly those resulting from infections incurred around the home or in the industrial workplace. Wounds due to agricultural or garden accidents are more likely to be contaminated with gram-negative or mixed organisms.

A felon, or whitlow, may begin as a subepidermal abscess that penetrates a pulp space of the finger. Further extension into adjacent fibrofatty spaces causes distention with severe pain and throbbing. If the spread continues, osteomyelitis of the distal phalanx may result in loss of the tuft, septic arthritis of the distal interphalangeal joint, or infective tenosynovitis of the flexor tendon sheath.
In the earliest phase, release of the subepidermal abscess and antibiotic treatment may abort the infection. However, when the felon is well established, incision and drainage are imperative. A longitudinal incision is made directly over the site of drainage or necrosis to minimize the chance of injuring a digital nerve. Blunt breakdown of septa with a hemostat allows for thorough drainage. A fishmouth incision or through- and-through incision is seldom necessary. A wick of gauze is left in the wound for 1 or 2 days, after which irrigation or soaks may be started.

Paronychia usually originates with an undetected break in the eponychium (cuticle) or with a hangnail. Dryness of the skin may be a factor, and the infectious organisms are often supplied from the patient’s nasopharynx. The early signs are redness and burning that spread along the nail fold. Pain is often inordinate for the apparent degree of inflammation. At this early stage, gently lifting the eponychium with a No. 11 blade evacuates the pus, allowing the inflammation to resolve without further treatment. A partial finger block suffices for anesthesia.
If untreated, the infection may progress beneath the nail, causing it to loosen. At this stage, excision of the proximal nail produces satisfactory decompression. A radial incision in the nail fold should be avoided. Some- times an incision halfway between the eponychium and the distal interphalangeal skin crease allows for direct drainage, accompanied by nail plate removal. Rarely, a mucous cyst simulates a paronychia or actually becomes infected. The infection may progress up the stalk of the cyst to the joint cavity, resulting in a septic distal interphalangeal joint.

Subcutaneous Abscess
Subcutaneous abscesses may occur anywhere in the fingers or hand and usually result from minute breaks in the skin that becomes infected. These infections present as pain, swelling, redness, and turgor. On the dorsum of the hand, abscesses are likely to originate in a hair follicle, or there may be several drainage sinuses that coalesce into a carbuncle.
Subcutaneous abscesses often have a purulent center, which aids identification. Incision and drainage are performed, with suitable regional anesthesia induced proximal to any obvious inflammation and avoiding areas of lymphangitis. The incision is centered over the fluctuant area, placed in skin creases, or angled at them obliquely. The incision should avoid underlying structures, particularly cutaneous nerves.
Also called subepidermal or vesicular cellulitis, pyoderma is most often seen in children and usually involves the dorsal aspect of the two distal segments of a finger. This infection is often due to Streptococcus from the nasopharynx, although both Staphylococcus and Pseudomonas species may also be present. The blebs may be aspirated and the fluid cultured to obtain definitive diagnosis, but the lesions invariably respond to antibiotics and protection from contact with the mouth. Pyoderma is highly contagious, and precautions should be taken to avoid spreading it to family members or schoolmates.
Herpes Simplex Cellulitis
A vesicular cellulitis of the hand or fingers due to infection with herpes simplex virus occurs most often in dentists and health care workers. Although the infection is contagious and often quite uncomfortable, it tends to run a benign course: several crops of vesicles develop slowly and heal over 2 to 3 weeks. The vesicles may be punctured under sterile conditions. Involved hands must be kept clean and dry, and the patient must be very careful to avoid further self-contamination or cross-contamination.

Tenosynovitis And Infection Of Fascial Space
Purulent tenosynovitis can be a devastating infection because it produces adhesions within the tenosynovial canal that markedly limit finger motion. If the infection affects one of the ulnar three fingers, the quadrigia effect may limit motion of the adjacent fingers as well. Once a granulation response has begun, the ability to restore full function is compromised. If treatment is delayed or the antibiotics used are insufficient or ineffective, the infection may convert to a subacute state that produces progressive destruction.
The infection is usually secondary to a puncture wound, and initial onset is insidious. Infection with a virulent organism such as Staphylococcus, however, can produce severe pain within a few hours. The four cardinal signs of tendon sheath infection (described by Kanavel) are uniform swelling, fixed flexion, pain on attempted passive extension of the finger, and tenderness along the course of the tendon sheath into the distal palm.
In the thumb and little finger, the tendon sheath usually extends into the radial and ulnar bursae, respectively, allowing infection to spread well into the distal forearm (see Plates 4-37 and 4-38). A communication between the two bursae allows the establishment of a horseshoe abscess that affects both the thumb and the little finger, although effective treatment with antibiotics has made this complication rare. By the time the horseshoe abscess occurs, irrevocable damage to the delicate gliding tissues of the tenosynovial sheath may have occurred. Avascular necrosis of the tendons follows quickly from vincular occlusion and intracompartmental pressure. Less virulent organisms cause a less acute infection, but if they are unrecognized and untreated, the residual effect may be no less detrimental.
A subcutaneous abscess directly over the tendon sheath may be confused with true purulent tenosynovitis. Therefore, if the diagnosis is not clear, incision and drainage should be performed. The initial incision is made over the site of maximum tenderness. If a subcutaneous abscess is found and the underlying sheath appears transparent and free of effusion, further dissection is not necessary. However, if there is effusion, purulence, distention, or thickening and opacity of the sheath, the incision should be extended as a Brunner zigzag incision.
To ensure adequate drainage and perfusion of the sheath, one or more flaps are raised at the sites of the cruciate pulleys. Any fluid should be aspirated and cultured immediately. If the tenosynovial sheath is inflamed, tissue samples should be sent for culture, Gram stain, and histologic examination. Determining the causative organism is essential because a number of unusual organisms, including Brucella, Pasteurella multocida, and various Mycobacterium species, may also induce tenosynovitis.
The tendon sheath can be milked by passive movements of the fingers. The sheath may also be irrigated through a small catheter, which is left in place for 1 or 2 days, and the effusion allowed to drain. The skin may be closed loosely to protect the underlying tendon. Active movement of the finger should be started once daily after surgery and continued under supervision but splinted and elevated between treatments. If the ulnar or radial bursa is involved, separate incisions are made at the wrist or the digital incisions extended, with care to preserve the transverse carpal ligament.
Sporotrichum schenckii, a fungus frequently found in soil or on garden plants, produces cutaneous and subcutaneous lesions and inflammation of the lymph vessels (lymphangitis). This indolent infection is characterized by a pilot lesion at the site of inoculation, followed by the appearance of a succession of satellite lesions, which progress proximally along a lymphatic chain. The lesions are raised, red, swollen, and usually about 1 cm in diameter; the center may ulcerate and drain. Pain is minimal. Diagnosis requires isolating the organism from the ulcerations.
The treatment of choice is topical application of potassium iodide, which is effective in the benign form of the disease. Lesions heal in 2 to 3 weeks. Sporotrichosis may remain localized or spread systemically to involve other organ systems.

Infection Of Deep Compartments
The deep compartments of the hand may become infected by direct inoculation via penetrating wounds or by extension of infection in adjacent areas. Such infections are relatively infrequent, but when present they cause rapid deleterious changes and are prone to spreading. Unless treated with incision and drainage, deep infection may cause permanent deformity.
Infection of Midpalmar Space
The midpalmar space lies under the flexor tendons of the ulnar three fingers and over the deep fascia covering the intrinsic muscles. Ulnarly, the hypothenar muscles and, radially, the adductor pollicis muscle define the space, which is partially separated by fibrous septa that attach the palmar floor to the central ridges of the metacarpal shafts. Purulence may enter or extend through the lumbrical canals or break through into the carpal canal or thenar space.
Symptoms such as pain on movement, swelling, and marked tenderness may rapidly increase in severity. The dorsum of the hand swells as the lymphatic drainage becomes involved. Tenosynovitis may also develop. The diagnosis is suggested by exquisite tenderness over the palm.
Treatment is by incision, which follows skin creases and is centered to allow access to the midpalmar space and retraction of the flexor tendons. The neurovascular bundles must be carefully identified and retracted. Usually, the purulence is under pressure when the mid- palmar space is opened and can be aspirated and the space irrigated. Extensions into adjacent spaces can be identified by massaging the palm, starting at the perimeter. Drains are inserted and kept in place for 1 or 2 days.

Infection of Thenar Space
The thenar space lies under the flexor tendons of the index finger and over the adductor pollicis muscle. The septum to the third metacarpal defines the ulnar border, and the thenar muscles define the radial border. The infection may extend into the lumbrical canal of the index finger and over the distal aspect of the adductor pollicis muscle. A dorsal thenar space infection on the dorsal aspect of the adductor pollicis muscle may dissect under the first dorsal interosseous muscle. An incision along the thenar space must avoid the recurrent motor branch of the median nerve. The nerve is identified by surface anatomic landmarks, using Kaplan’s cardinal line intersection with the thenar crease. The incision can be extended distally as a Z-plasty over the first web space.
Collar Button Abscess
These types of abscesses derive their name from the dumbbell-shaped contour of the abscess around the margin of the superficial transverse metacarpal ligament in one of the web spaces. Thus, they may present on both dorsal and volar aspects of the hand. Drainage is through a zigzag incision over the distal web space.
Infection of Parona Space
The Parona space lies deep to the flexor tendon sheaths in the distal forearm and volar to the pronator quadratus muscle. Infections are usually due to direct inoculation or extension from an infection of the tendon sheaths. An abscess may be drained through a direct palmar incision if the radial and ulnar bursae are involved. The median nerve must be identified and protected. If the tendon sheaths are not involved, an incision between the flexor tendons and ulnar neurovascular bundle allows access to the Parona space, as does a direct ulnar incision sliding along the pronator quadratus muscle.
Infections from Human and Animal Bites
Teeth carry a variety of virulent organisms, and a bite may inoculate these organisms deeply into tissues of the hand. Most dogs and cats are carriers of Pasteurella multocida, an organism that produces a rapidly spreading inflammation that may penetrate subcutaneous and subfascial spaces as well as tendon sheaths and deep compartments. More aggressive and earlier treatment is required for cat bites because delayed surgical treatment leads to very slow resolution of infection. Human bites carry streptococcal, staphylococcal, spirochetal, and gram-negative organisms. Eikenella corrodens is an especially invasive organism that is difficult to eradicate. Penetration of the metacarpophalangeal joint by an incisor may lead to a destructive septic arthritis and dissemination of infection into the adjacent spaces. Treatment of this type of infection requires early recognition, adequate incision, and irrigation.

Lymphangitis often originates from an insignificant break in the skin or a small wound in the hand. Pain and a burning erythema develop at the site of inoculation. Lymphangitic erythematous streaks begin to form over the dorsum of the hand, progressing in just a few hours into the forearm and then into the arm. Pain intensifies and fever and chills develop. The axilla and epitrochlear areas become tender and swollen.
On examination, the patient appears anxious, protects the involved arm, and may shiver with chills. The wound and the lymphangitic streaks are tender to the touch, as are the soft, swollen epitrochlear and axillary nodes. There may be a small serous drainage at the wound site, which should be cultured and Gram stained. Because streptococci are the usual causative organisms, treatment with penicillin or cephalosporin is started immediately. The perimeter of the erythema at the wound site and the lymphangitic streaks can be marked with a pen for later reference, and the size of the nodes is noted. If the infection does not respond to treatment with antibiotics or if the signs worsen in 12 to 24 hours, a culture sample should be obtained by aspiration or incision or the antibiotic regimen should be changed.
Necrotizing Fasciitis
Also called a Meleney ulcer, necrotizing fasciitis is a severe manifestation of lymphangitis that progresses in a frightening manner within a few hours. Anaerobic or microaerophilic streptococci are believed to be the usual cause, but these microorganisms are difficult to culture.  Tissue necrosis develops rapidly behind an advancing wall of inflammation that limits penetration by antibiotics. Desquamation followed by gangrene may be relentless. The clinical signs of pain, hyperpyrexia, and chills are severe.
The skin lesions are incised and drained or aspirated to obtain fluid for culture. Intravenous infusion of aqueous penicillin must be instituted immediately; additional antibiotics may be recommended by an infectious disease specialist. The progress of the inflammation and necrosis must be carefully monitored. Surgical intervention within hours is often required to save life and limb. Even when the necrotizing lymphangitis is controlled early, however, autoamputation may be a sequela and death is an occasional outcome.
Other Hand Infections
The preceding discussion is merely an introduction to the greater scope of infections of the hand. Mycobacterial tenosynovitis and arthritis still occur. Mycobacterium marinum is an organism frequently associated with injuries due to marine activities. Gonococcal septic arthritis rapidly destroys involved joints. Rare invaders of the musculoskeletal system are fungal infections, including coccidioidomycosis and blastomycosis. Clostridium perfringens may colonize crushed muscle in the hand, producing gas gangrene. Rare viral infections transmitted from domestic animals occasionally produce lesions on the hand, and inflammation that mimics infection (e.g., calcium pyrophosphate dihydrate disease) should also be considered in the differential diagnosis.
The introduction of antibiotics has dramatically improved the prognosis for infections of the hand. For optimal treatment, however, the correct diagnosis must be established, the organism identified, the purulence drained, and an appropriate rehabilitation program instituted.