Factors Influencing Hand Infections

The clinical course of most hand infections is affected by anatomical, local, and systemic factors, in addition to bacterial virulence and the size of the inoculum. Anatomical factors that to some extent determine the ease of penetration, localization, and spread of infection include (1) the thin layer of skin and subcutaneous tissue over the tendons, bones, and joints; (2) the closed space of the distal digital pulp; (3) the proximity of the flexor tendon sheath to bone and joint; (4) the proximal extent of the flexor sheath into the palm, connecting with the radial and ulnar bursae; and (5) the location of the thenar and midpalmar spaces in the hand and the space of Parona proximal to the wrist near the flexor tendon sheaths.

Local factors predisposing to infection include (1) the extent and nature of soft tissue damage, (2) the amount and virulence of bacterial contamination, and (3) the type and amount of foreign material present and persistent in the wound. Systemic factors generally are considered to be factors that have an effect on the immunocompetence of the patient and include (1) malnutrition, (2) alcoholism, (3) intravenous drug abuse, (4) diabetes mellitus, (5) long-term use of corticosteroids and anti–tumor necrosis factor-α medicines, (6) immunosuppression following solid organ and bone marrow transplant, and (7) infection with human immunodeficiency virus.

Treatment of hand infections depends on the identification of the specific organism, the specific anatomical area involved, the location of the infection in the hand and fingers, and the type of inflammation and areas of tenderness and erythema, as determined by palpation and observation. Identification of organisms with culture and antibiotic sensitivity studies allows proper medical treatment. Surgical procedures, including drainage of abscesses and débridement of necrotic tissues, also may be required.

General Approach to Hand Infections

With a careful history and physical examination, the location of the infection, the extent of spread, and the presence of swelling, lymphangitis, lymphadenitis, and joint involvement can be determined. Consideration should be given to other conditions that can be confused with infections, including gout, acute calcium deposition, pseudogout, pyogenic granuloma, insect bites, pyoderma gangrenosum, foreign bodies, factitious lesions, herpetic lesions, metastatic lesions, silicone synovitis, granuloma annulare, rheumatoid arthritis, nonspecific tenosynovitis, reactions to intravenous medications (e.g., chemotherapeutic agents), and Sweet syndrome, an aseptic neutrophilic dermatosis affecting the hand and resembling an infection. If the likelihood of infection is high, an attempt should be made to determine whether an abscess is present that requires drainage. Fluctuance can be difficult to identify in the hand. Radiographs are helpful in revealing bone injury. Radionuclide scanning may show bone infection, and MRI and ultrasound may localize an abscess. A complete blood cell count is obtained, along with determination of the serum C-reactive protein level and erythrocyte sedimentation rate. If any fluid or tissue is obtained, it is sent to the laboratory for Gram stain, culture, and antibiotic sensitivity determinations. Specific requests usually are made of the laboratory to culture for aerobic and anaerobic bacteria and for mycobacteria and fungi. In some cases, viral testing also can be helpful.

Initial antibiotic therapy traditionally has been empirical, depending on the results of the Gram stain and the most likely organism. Consideration should be given to the possibility of mixed flora as the cause of hand infections. Reviews of surgical infections of the hand and upper extremity have shown an increase in the incidence of gram-negative enteric and anaerobic organisms, even though the most common organisms were gram-positive aerobes (streptococcal species, Staphylococcus aureus, and coagulase-negative Staphylococcus). Generally, the organism most commonly isolated from community-acquired hand infections is S. aureus. Typically, 80% or more of wounds cultured from swabs produce multiple organisms, whereas tissue specimens may produce a single causative organism in about 75%. Other organisms that commonly cause hand infections include streptococci, enterobacteria, Pseudomonas, enterococci, and Bacteroides. Less common causes include the various mycobacteria, gonococcus, Pasteurella multocida (in cat or dog bites), Eikenella corrodens (in human bites), Aeromonas hydrophila from standing fresh water (e.g., ditches, puddles, and ponds), Haemophilus influenzae (in children 2 months to 3 years old), a variety of anaerobic organisms (including clostridia), and other rare bacteria, such as those that cause anthrax, erysipeloid, and brucellosis. Postoperative or surgical site infections of the hand usually are caused by gram-positive organisms, including S. aureus and Staphylococcus epidermidis. Gram-negative organisms also may be isolated from surgical site infections.

Antibiotics traditionally recommended for hand infections include a penicillinase-resistant penicillin or cephalosporin. When selecting antibiotics, it is important to be aware of the prevalence of antibiotic-resistant bacteria, such as methicillin-resistant S. aureus (MRSA), which is growing in prevalence in hand infections. Antibiotic resistance is seen in up to 65% of Staphylococcus cultures. Vancomycin is effective against the gram-positive organisms, whereas ciprofloxacin is most effective against the gram-negative organisms. The addition of antibiotics effective against gram-negative organisms has been recommended for high-risk situations, such as infections in intravenous drug users and contaminated outdoor or farm injuries. In Tables 78-1 and 78-2 a summary is provided of the appropriate use of antibiotics, antifungal agents, and antiviral agents. Because of the constantly changing inventory of antibiotics and the variations in patient populations and wound flora, antibiotic selection should be based on a variety of considerations and include the assistance of an infectious disease specialist when needed.

TABLE 78-1 Selected Antibacterial Agents

TABLE 78-2 Selected Antifungal and Antiviral Agents

A protocol of early, aggressive surgical incision and drainage combined with intravenous antibiotic therapy should result in a shorter hospital stay, faster healing, and fewer complications. Current recommendations for outpatient antibiotic treatment include amoxicillin and clavulanate plus trimethoprim and sulfamethoxazole. Failure to recognize the polymicrobial nature of hand infections and inadequate surgical débridement are frequent causes of poor results. The importance of adequate surgical treatment cannot be overemphasized because antibiotics alone may be insufficient to control the infection.

Paronychia

A paronychia (“runaround”) infection usually is caused by the introduction of S. aureus into the soft tissue fold around the fingernail (eponychium) associated with a hangnail or poor nail hygiene (Fig. 78-1). When an abscess forms in the eponychial or paronychial fold, it is known as a paronychia. It usually begins at one corner of the horny nail and travels under either the eponychium or the nail toward the opposite side. If an abscess is on one side only, it should be incised, angling the knife away from the nail to avoid cutting the nail bed, which would cause a ridge later. If the abscess is under one corner of the nail root, this corner should be removed. If it has already migrated to the opposite side and under the nail, a second incision should be made there, the skin folded back proximally, and the proximal one third of the nail excised. The wound is loosely packed with iodoform gauze for 48 hours for drainage (Fig. 78-2).

FIGURE 78-1 Diagram of nail and nail bed. A, Nail. B, Eponychium. C, Dorsal roof of nail fold. D, Ventral floor of nail fold (germinal matrix). E, Nail bed (sterile matrix).

(From Bednar MS, Lane LB: Eponychial marsupialization and nail removal for surgical treatment of paronychia, J Hand Surg 16A:314, 1991.)

FIGURE 78-2 Incision and drainage of paronychia (see text).

Infections caused by herpes simplex virus type 1 or 2 may be confused with bacterial paronychia. The “herpetic whitlow” is seen more often in health care workers and in immunocompromised patients and begins as a localized area of swelling with clear vesicle formation. Lymphangitis and lymphadenopathy may be present. The diagnosis can be confirmed with viral cultures of fluid from the vesicles, a Tzanck smear, and serum antibody titers. The condition is self-limited, usually resolving over 3 to 4 weeks, and does not require surgical treatment.

Chronic Paronychia

Chronic paronychia typically occurs in patients whose activities require prolonged exposure to water. With chronic inflammation and recurring infection, the eponychium appears thickened and prominent. Organisms obtained from the cultures of these lesions include Staphylococcus pyogenes, S. epidermidis, Candida albicans, colonic gram-negative bacteria, or a mixture of these. Tosti et al. compared topical methylprednisolone with two oral antifungal medicines in the treatment of chronic paronychia of 45 patients with multiple nail involvement. Methylprednisolone cured or improved 85% of the nails. Of the oral antifungal medications, terbinafine was effective in 52% and itraconazole was effective in 45%, suggesting the possibility that a chronic paronychia is more likely a dermatitis related to environmental exposure.

Eponychial Marsupialization

Bednar and Lane found the eponychial marsupialization technique of Keyser and Eaton to be effective in curing patients of chronic paronychia. They further noted that if nail irregularities are present, removing the nail leads to healing without recurrence.

Technique 78-2

(BEDNAR AND LANE; KEYSER AND EATON)

After administering a digital block anesthetic, cleanse the finger with antiseptic and drape it appropriately.

Excise a crescent of skin 3 mm wide parallel to the eponychium and extending from the radial to the ulnar borders (Fig. 78-3).

When using the Keyser and Eaton technique, remove all thickened tissue from the skin. Bednar and Lane leave the subcutaneous fat intact.

If nail irregularities are present, remove the nail.

Cover the wound with petroleum/bismuth tribromophenate–impregnated gauze (Xeroform). If the nail is removed, place this gauze beneath the nail fold.

FIGURE 78-3 Eponychial marsupialization for treatment of paronychia. Symmetrical, crescent-shaped segment of skin is excised from dorsum of distal phalanx, leaving adequate bridge of skin and cuticle. SEE TECHNIQUE 78-2.

Postoperative Care

Therapy with an oral antibiotic (cephalexin or erythromycin) is begun postoperatively. The patient is instructed to soak the finger in hydrogen peroxide and to wash it with chlorhexidine gluconate skin cleanser (Hibiclens) three times daily, beginning on postoperative day 3. The daily washings are continued until all drainage stops. Antibiotics should be continued for 2 weeks. If the culture results are negative, antibiotics can be discontinued in 3 to 5 days.

Pabari et al. described a “Swiss roll” technique for treatment of both acute and chronic paronychia in which the nail fold is elevated and reflected proximally over a nonadherent dressing and secured to the skin with a nonabsorbable suture (Fig. 78-4). Cited advantages of this technique are retention of the nail plate, rapid healing, and avoidance of a skin defect in the finger.

FIGURE 78-4 “Swiss roll” technique for treatment of paronychia. A, Inflamed germinal matrix is exposed and thoroughly irrigated. B, Elevated nail fold is reflected proximally over a nonadherent dressing, rolled like a Swiss role, and secured to the skin with nonabsorbable suture.

(From Pabari A, Iyer S, Khoo CT: Swiss roll technique for treatment of paronychia, Tech Hand Up Extrem Surg 15:75, 2011.)

Felon

A felon is an abscess in the subcutaneous tissues of distal pulp of a finger or thumb. The distal digital pulp is divided into tiny compartments by strong fibrous septa that traverse it from skin to bone. A transverse fibrous curtain also is present at the distal flexor finger crease. Because of these septa, any swelling causes immediate pain that is intensified because of increased pressure within the pulp. Infection can be caused by a penetrating injury from a foreign body or from “finger sticks” for medical reasons (e.g., hematocrit and blood glucose determinations). S. aureus is the organism most commonly isolated from fingertip infections. Swelling, redness, and pain, typical of cellulitis, initially are present. Abscess formation may follow rapidly. The pulp abscess (felon) can extend into the periosteum, around the nail bed, or proximally through the fibrous curtain into the flexor sheath or through the skin to the exterior over the pulp. Abscesses beginning deep, especially if untreated, penetrate the periosteum and cause osteomyelitis; the more superficial ones cause skin necrosis. Abscesses may form occasionally in the middle and proximal digital pulps.

Treatment consists of antibiotics and incision for drainage. The diagnosis of an abscess in this area is sometimes difficult, but one usually is present if severe pain has lasted for 12 hours or longer.

Incision and Drainage of Felons

Technique 78-3

When the abscess points volarward, causing necrosis of the overlying skin, drain it by excising the necrotic skin.

When the abscess is in the distal pulp area pointing volarward toward the whorl of the fingerprint, it is best drained by a vertical incision begun distal to the skin crease and placed precisely in the midline to avoid the lateral branches of the digital nerve and to allow healing with minimal scar (Fig. 78-5).

If the abscess is deep and is partitioned by the septa, make a longitudinal incision, usually away from the contact area of the finger, cutting through the partitions (Fig. 78-6).

This incision must be accurate. Make the incision dorsal to the tactile surface of the finger and not more than 3 mm from the distal free edge of the nail; otherwise, the ends of the digital nerve would be painfully damaged. Blunt dissection with the tip of a small scissors or a mosquito hemostat avoids sharp injury to nerve endings, allowing disruption of the fibrous septa and adequate drainage. A J-shaped incision is sufficient; a fishmouth incision around the whole fingertip is slow to heal and can result in painful scarring, especially if it is placed too far palmar.

Irrigate the wound copiously, and pack it with iodoform gauze or sterile gauze bandage.

FIGURE 78-5 Midline vertical incision for drainage of abscess pointing volarward in distal pulp of finger. SEE TECHNIQUE 78-3.

FIGURE 78-6 Incision and drainage of felon. SEE TECHNIQUE 78-3.

Postoperative Care

The finger is splinted, and elevation is maintained. The bandage is changed at about 48 hours. Dressing changes are then begun, with soaking the hand in saline solution and allowing secondary healing. Active range-of-motion exercises, edema control, and gradual reincorporation of the finger into activities of daily living are emphasized. Antibiotic treatment with first-generation cephalosporins has usually been sufficient; however, changes in antibiotic therapy should be made on the basis of the results of culture and sensitivity studies. Infections in patients with diabetes or immunosuppression may be difficult to control, and amputation may be the end result.

Subfascial Space Infections

The potential spaces in the subfascial and deeper layers of the hand are infrequently infected. A high level of suspicion should lead to their detection and treatment. The recognized deep spaces of the hand include the interdigital web spaces, the midpalmar space, the thenar space, a less well-defined hypothenar space, the Parona space, and the dorsal subaponeurotic space (Fig. 78-7).

FIGURE 78-7 Cross-sectional anatomy of hand showing thenar, midpalmar, hypothenar, interdigital (web), and dorsal subaponeurotic spaces.

(Redrawn from Jebson PJ: Deep subfascial space infections, Hand Clin 14:557, 1998.)

Web Space Infection (Collar Button Abscess)

Web space infection usually localizes in one of the three fat-filled interdigital spaces just proximal to the superficial transverse ligament at the level of the metacarpophalangeal joints. Typically, the infection begins beneath palmar calluses in laborers. It may begin near the palmar surface, but because the skin and fascia here are less yielding, it may localize to drain dorsally. Here the tissue becomes obviously swollen, but the significant amount of the abscess remains nearer the palm. This may be the more dangerous part because, unless drained, it may spread through the lumbrical canal into the middle palmar space. Two longitudinal incisions usually are necessary for drainage: one on the dorsal surface between the metacarpal heads and the other on the palm, beginning distal to the distal palmar crease and curving proximally. Crossing the palmar creases at right angles to the crease should be avoided (Fig. 78-8). The web should not be incised.

FIGURE 78-8 A, Lines show palmar incisions for web abscess drainage. B, Dorsal incision.

Deep Fascial Space Infections

The palmar fascial space lies between the fascia covering the metacarpals and their contiguous muscles and the fascia dorsal to the flexor tendons. Its ulnar border is the fascia of the hypothenar muscles, and its radial border is the fascia of the adductor and other thenar muscles. This space is divided into a middle palmar space and a thenar space by a fascial membrane that passes obliquely from the third metacarpal shaft to the fascia dorsal to the flexor tendons of the index finger (Fig. 78-9). The hypothenar space has as its boundaries: the hypothenar septum laterally, the fifth metacarpal dorsally, and the hypothenar muscle fascia medially and palmar. The space of Parona is bordered by the pronator quadratus dorsally, the flexor pollicis longus laterally, the flexor carpi ulnaris medially, and the flexor tendons on the palmar aspect; it rarely is the site of abscess formation. Infections in these spaces are now rare because less extensive infections nearby usually are controlled by antibiotics before they spread. Abscesses in these spaces usually result from the spread of infection from other parts of the hand, typically from purulent flexor tenosynovial infections.

FIGURE 78-9 Boundaries of deep palmar space, which is divided into thenar space and middle palmar space (see text). A, Abscess in thenar space. B, Abscess in middle palmar space. C, Relationships of spaces when not distended by pus.

A middle palmar abscess can cause a severe systemic reaction, local pain and tenderness, inability to move the long and ring fingers actively because of pain, and generalized swelling of the hand and fingers, which resembles an inflated rubber glove. A thenar abscess causes similar symptoms, but the thumb web is more swollen, the index finger is held flexed, and active motion of the index finger and the thumb is impaired because of pain.

Incision and Drainage of Deep Fascial Space Infection

Technique 78-4

Drain the middle palmar space through a curved incision beginning at the level of the distal palmar crease, in line with the long finger and extending ulnarward to just inside the hypothenar eminence (Fig. 78-10). Other options include the longitudinal distal palm incision and the transverse palm incision.

Enter the space on either side of the long flexor tendon of the ring finger with a blunt instrument, such as a hemostat, to avoid injury to neurovascular structures. Leave a drain in place if needed.

Drain the thenar space through a curved incision in the thumb web parallel to the border of the first dorsal interosseous muscle or along the medial side of the thenar crease (Fig. 78-11). Avoid the recurrent branch of the median nerve at the proximal end of this crease. Avoid sharp, deep dissection, using blunt dissection to delineate the extent of the abscess.

Drain Parona space infections through a straight or curved incision on the palmar forearm. Begin the incision just proximal to the wrist flexion crease, slightly medial to the midaxial line. Extend the incision proximally sufficiently to allow exposure of the flexor tendons and median nerve that lie immediately beneath the fascia.

Retract the flexor tendons and median nerve, protecting them.

Drain the abscess, and irrigate the wound. If needed, place a Penrose drain or tube for irrigation in the wound.

Apply a nonadherent gauze and bulky absorbent dressing. Splint the wrist in a position to allow functional motion of the fingers.

Change the bandage frequently, irrigating as needed. Usually, healing by secondary intention is satisfactory. If the infection and drainage can be controlled rapidly, secondary closure or skin grafting may be appropriate.

If the infection and drainage cannot be controlled rapidly, healing by secondary intention is preferred.

FIGURE 78-10 A, Distal longitudinal palmar incision. B, Transverse palmar incision. C, Extended longitudinal palmar incision. SEE TECHNIQUE 78-4.

FIGURE 78-11 A, Thenar crease incision (palmar). B, Dorsal longitudinal incision. SEE TECHNIQUE 78-4.

Tenosynovitis

An infection within the flexor tendon sheath may be the result of the spread of adjacent pulp infections or puncture wounds in the flexor creases. Although the flexor sheath usually is involved, the radial and ulnar bursae may be involved as well. Kanavel considered tenderness over the involved sheath, rigid positioning of the finger in flexion, pain on attempts to hyperextend the fingers, and swelling of the involved part to be the four cardinal signs of suppurative tenosynovitis. Of these, tenderness over the flexor sheath is considered the most significant. When early tenosynovitis is suspected, immediate treatment with antibiotics and splinting may abort spread of the infection if the patient’s symptoms have been present for less than 48 hours. If nonsurgical treatment is selected, these patients should be followed closely, because the consequences of noncompliance can be devastating to the digit and hand. Good results have been reported in patients with pyogenic flexor tenosynovitis treated with surgical drainage, followed by outpatient management of intravenous antibiotics, wound care, and rehabilitation. Patients with infection after penetrating injuries usually are infected with S. aureus; however, Streptococcus also may be found. Under ideal circumstances, fluid should be obtained from the sheath for Gram stain, culture, and antibiotic sensitivity testing. If gross pus is obtained from aspiration of the digital flexor sheath, surgical drainage usually is indicated. Purulent fluid might not be present in the flexor sheath with overlying cellulitis; however, needle aspiration of the sheath through cellulitic tissue creates the risk of inoculating the uninfected sheath with bacteria. An increasing frequency of MRSA hand infections has been documented in clinical studies. Vancomycin was effective for infections caused by gram-positive bacteria, whereas ciprofloxacin was most effective for gram-negative organisms, including Pseudomonas. With persistent tenosynovial infection, pressures within the flexor sheath can exceed 30 mm Hg, rendering the tendons ischemic in the presence of infection. Delay in treatment may lead to damage to the flexor tendon and sheath, with resulting adhesion, loss of excursion, finger stiffness, and impaired function. The prognosis for function is poor if an infection here produces pus that must be drained. If drainage is required, an open or closed irrigation technique can be used. If an open technique is used, healing and rehabilitation are prolonged and full motion may not be regained.

Postoperative Closed Irrigation

Closed postoperative irrigation is appropriate and effective for infections that yield serous exudate or purulent fluid on opening the flexor sheath and for infections that are relatively acute. Some have found that closed catheter irrigation was as effective as open drainage of pyogenic flexor tenosynovitis. If the infection is chronic, or if the flexor tendon is grossly necrotic, open drainage may be necessary.

Technique 78-5

(NEVIASER, MODIFIED)

With the patient under suitable anesthesia and after appropriately preparing and draping the hand and arm, inflate a pneumatic tourniquet; however, to reduce the risk of spreading the infection, do not wrap the limb.

Expose the proximal end of the flexor sheath in the region of the A1 pulley by a straight transverse incision parallel to the distal palmar crease or by a zigzag incision in this area (Fig. 78-12). Expect to see serosanguineous or purulent fluid in the sheath.

Open the sheath proximal to the A1 pulley, and swab the fluid to send for cultures.

Make a second incision in the midaxial line on either side of the finger in the distal portion of the middle segment of the digit.

As an alternative, carefully make a transverse incision over the distal flexion crease.

Open the flexor sheath distal to the A4 pulley.

Using smooth forceps or hemostats, pass a 16-gauge or 18-gauge polyethylene catheter beneath the A1 pulley from proximal to distal in the flexor sheath for 1.5 to 2 cm. Distally place a small piece of rubber drain beneath the A4 pulley, and bring it out through the skin incision. Irrigate the sheath from proximal to distal with saline.

Close the wounds around the catheter and the rubber drain, leaving the distal wound sufficiently loose to allow fluid to drain. Suture the catheter to the palmar skin. Test the system for patency by irrigating freely with saline.

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