Acute Infections of the Hand

Methicillin-Resistant Staphylococcus aureus Infections

The increasing incidence of infection with methicillin-resistant S. aureus (MRSA) has been recognized throughout the surgical and infectious disease literature. A strain of S. aureus resistant to methicillin was mentioned in reports from the United Kingdom in 1961. This strain was soon identified worldwide and was associated with hospital-acquired infections (HA-MRSA). Only a handful of successful HA-MRSA clones are responsible for the majority of infections, and different clones dominate in different geographic locations. However, MRSA infections have been increasingly identified as community-acquired infections (CA-MRSA). There are unique microbiologic and genetic properties distinguishing the hospital-acquired and community-acquired strains. A community-acquired infection is defined as occurring in patients with MRSA identified by culture who have no history of a hospital or medical facility stay within the past year, who have no history of dialysis or surgery occurring within the past year, and in whom no indwelling catheters are present.

CA-MRSA is now the predominant strain in hand infections, found in up to 40% to 60% of S. aureus infections. The majority of CA-MRSA infections in the United States have been caused by a single clone (USA300). One of the distinguishing features in CA-MRSA is the frequent gene sequence encoding for Panton-Valentine leukocidin (PVL), a potent toxin that leads to the characteristic tissue necrosis commonly seen in the clinical setting. Of recent concern is the increased incidence of multidrug-resistant MRSA, with resistance to clindamycin and levofloxacin. Kistler et al. reported on the patient factors associated with specific drug resistance. Risk factors for clindamycin resistance included nosocomial infections, a history of intravenous drug use, and hepatitis C. Risk factors for levofloxacin resistance included a history of diabetes and a fever upon initial presentation. ^{, ,}

MRSA infections frequently have a characteristic appearance of a dermonecrotic skin lesion ( Fig. 2.1 ). They are often mislabeled by patients as “spider bites” due to their appearance. Recently, we have not seen the extensive tissue necrosis with MRSA infections that we have in the past. Empirical treatment of hand infections has also changed to address potential MRSA infections. ^{, , ,} Successful treatment requires surgical debridement with excision of necrotic tissue in conjunction with appropriate antibiotic therapy.

Nosocomial Infections

The hand is a very well-vascularized region, making it less vulnerable to postoperative infection than other anatomic sites, with an incidence of deep postoperative infection of less than 1%. S. aureus is the most common pathogen in clean surgical procedures. The use of perioperative intravenous antibiotics within 1 hour preceding surgery has greatly reduced the incidence of postsurgical infections in general orthopedic practice. The benefit of perioperative intravenous antibiotics in the total joint population was generalized to all orthopedic procedures, leading to antibiotic overuse for clean soft tissue procedures. In particular, the use of perioperative antibiotics in elective hand surgery has been overused despite strong support that it does not decrease the incidence of surgical site infections in elective soft tissue procedures of the hand. ^, The use of antibiotics may be related in part to institutional policies rather than to surgeon preference. Ultimately, the whole patient and any underlying comorbidities must be considered. Prophylactic antibiotics in patients with joint arthroplasties have been recommended to protect the prosthesis more than to prevent surgical site infection, although one recent study has demonstrated no difference in prosthetic joint infection with or without prophylactic antibiotic therapy. Patients with an altered immune response may have a potentially greater benefit from prophylactic antibiotics than an immunocompetent host. For surgical procedures that involve exposure of the bone or joint or those involving implants, we routinely administer intravenous prophylaxis.

Surgical site preparation has transitioned predominantly to the use of prep sticks to clean the surgical site. Recent studies suggest that the use of DuraPrep and Betadine were better than ChloraPrep for skin decontamination in the hand, with the majority of pre and post-prep colonies consisting of Bacillus species. Beredjiklian and colleagues showed a five times greater area of unprepped skin surface when comparing a prep stick to soaked 4 × 4 gauze sponges. However, both methods demonstrated <1% unprepped skin surface area. Given the low rate of infection following clean surgery of the hand, the clinical implications remain unknown.

Clinical Presentation and Preoperative Evaluation

Erythema, swelling, and tenderness immediately adjacent to the nail are the hallmarks of the early clinical presentation. If left untreated, an abscess may form along the nail fold. The abscess may extend below the nail plate, either partially or completely, or it can track in a volar direction into the pulp space. Because of the continuity of the nail fold with the eponychial tissue overlying the base of the nail, the infection can extend into this region and may continue around to the fold on the opposite side of the fingernail. This unusual occurrence is called a “runaround infection.” Infection involving the entire eponychium, as well as one lateral fold, is known as an eponychia. An eponychia is usually manifested as a collection of pus beneath the proximal portion of the nail in the region of the lunula. It is rare to see both lateral folds and the dorsal tissue infected in the same digit.

Radiographs and laboratory examination are not necessary in uncomplicated cases with early clinical findings. However, patients who have not responded to initial treatment, have recurrent infection, or who present with considerable swelling or abscess should be evaluated for underlying systemic diseases such as diabetes. The patient’s history and examination will direct the need for wound cultures for atypical organisms, radiographs to evaluate for a foreign body or osteomyelitis, and laboratory evaluation. Empirical therapy usually is a first-generation cephalosporin. For patients who are noted to be nail biters, a penicillin with a beta lactamase inhibitor may be a better antibacterial agent to cover E. corrodens. Patients who do not respond to empirical therapy with a first-generation cephalosporin may also have CA-MRSA infection and may respond to a change in antibiotic therapy.

Treatment Options

In the very early stages, this infection can be treated by soaks in a warm solution, systemic oral antibiotics, and rest of the affected part. If there is a superficial abscess, treatment can be carried out with local anesthesia and should consist of elevation of the cuticle away from the nail plate in the area of erythema and opening the thin layer of tissue over the abscess with a sharp blade directed away from the nail bed and matrix. Drainage of the abscess is performed where the abscess most nearly approaches the surface ( Fig. 2.4 ). The patient is counseled regarding high-risk activities, such as nail biting and manicures.

More extensive infection requires individualized treatment based on the extent of the lesion. Surgical decompression is best carried out under digital block anesthesia at the level of the metacarpal head with plain lidocaine. If the perionychial fold and the adjacent part of the eponychium are involved, the perionychium and skin adjacent to the nail fold are released. If the perionychial infection tracks in a volar direction and involves the pulp, the incision should be deep enough to fully drain the abscess and allow evaluation of bone involvement of the distal phalanx. Infection that travels below the nail plate requires removal of a portion of the nail. If the entire nail matrix is involved, then the entire nail is removed. Purulence below the nail plate can cause pressure on the germinal matrix, resulting in ischemia of the germinal matrix and temporary or permanent arrest of nail growth.

Operative methods

The paronychial sulcus is elevated from the nail gently by a flat, blunt instrument, such as the flat portion of a small malleable or metal probe or a Freer elevator. Sharp incision may be used as well. The incision is directed away from the nail bed to avoid injury to the nail bed and subsequent growth abnormality. The incision may be extended proximally along the nail fold, as far proximally as is necessary ( Fig. 2.5A and B). It is generally sufficient to carry the incision only to the proximal edge of the nail, but it may extend as far proximally as the distal interphalangeal (DIP) joint.

When abscess or fluctuance is found below the eponychium and a single incision does not adequately expose or decompress the involved tissues, a parallel incision along the opposite nail fold is made, allowing the eponychium and nail fold to be elevated and reflected above the nail plate (see Fig. 2.5C to E).

When the abscess extends below the nail plate, a portion of the nail plate should be removed. The amount and location of nail removal depend on the location and extent of involvement below the nail. If the area of fluctuance lies adjacent to the perionychium, a flat blunt probe or Freer elevator is used to separate the affected portion of the nail plate from the nail bed. The nail plate is then cut with a small scissors and removed. In the rare case where the eponychium is infected and pus is present only below the proximal portion of the nail, the eponychium and nail plate are elevated through a single or double incision. The proximal third of the nail plate is carefully removed. Only when the nail is entirely separated from the underlying matrix is it necessary to remove the entire nail plate. After decompression, the area of abscess is irrigated. The wound is left open with a small thin piece of gauze that allows the wound to stay open and drain.

Postoperative Management and Expectations

Postoperatively, the patient is given oral antibiotics for 7 to 10 days, depending on the severity of the infection. Dressings are changed two to three times per day, coinciding with soaking of the affected finger for 5 to 10 minutes. We discontinue packing or wicking the wound at 3 to 4 days, or when the infection has resolved and the wound is healing. Occlusive dressings can lead to skin maceration and should be avoided. Early motion is emphasized to prevent stiffness.

Improvement is noted in most acute cases of paronychia in 3 to 4 days with appropriate management; however, some tenderness and hypersensitivity around the surgical scars can be expected for several months. Nail deformity can occur either as a result of the infection or after iatrogenic injury to the nail matrix. Patients with an underlying medical illness may require a longer time for healing, recover more slowly, require additional surgery, and have a higher risk of recurrent infection.

Complications are rare but do occur. Nail deformity can occur either from the infection itself or from iatrogenic injury to the nail matrix during decompression. The risk of injury is minimized by gently separating the nail plate from the underlying matrix and by directing the scalpel blade away from the matrix when incising around the nail bed. Persistent infection despite appropriate treatment may be due to insufficient surgical decompression and drainage or inadequate antibiotic coverage. If the infection is not resolving at 1 week, radiographs to evaluate for osteomyelitis, cultures with antibiotic sensitivities, and repeat surgical debridement are necessary. Robbins, in his series from the 1950s, found that the most frequent complication of a paronychia was extension to the pulp space through a sinus at the side of the nail. This complication occurred in 13.5% of his patients. Today, the spread to the pulp space is rare owing to improved antibiotic therapy and more aggressive surgical treatment. In children with long-standing paronychia, infection can lead to bone involvement (osteomyelitis) and epiphyseal separation.

Misdiagnosis of a paronychia can occur, particularly confusion with herpetic whitlow. Distinguishing herpetic whitlow from a bacterial infection is important. Incision and drainage of herpetic whitlow are contraindicated and can result in systemic viral infection and/or bacterial suprainfection.

Clinical Presentation and Preoperative Evaluation

Chronic paronychia is characterized by indurated and rounded eponychium and is a distinct problem from acute paronychia. Chronic paronychia was once felt to be a result of repeated bacterial and fungal infections; however, the current view suggests that chronic paronychia represents a eczematous condition with multifactorial etiology. ^, This problem is more common in middle-aged women, with a female-to-male ratio of 4:1. Frequent water immersion, particularly in detergents and alkali solutions, is a predisposing factor. Housewives, bartenders, dishwashers, nurses, swimmers, and children who suck their fingers are often affected. Chronic paronychia also more commonly affects patients with diabetes and psoriasis. Cultured organisms include gram-positive cocci, gram-negative rods, Candida, and mycobacterial species. Preoperative evaluation includes a thorough history for contributing environmental factors and laboratory evaluation for underlying systemic diseases such as diabetes or immunosuppression. Radiographic evaluation is also indicated assessing for a foreign body, osteomyelitis, or a bony lytic or blastic process that could indicate a tumor (primary or metastatic). If the lesion is suspicious for a tumor, an MRI study may be tumor required.

Treatment

Conservative therapies for chronic paronychial infection have included topical corticosteroids, topical tacrolimus, oral and topical antibiotics, and oral and topical antifungal agents. Although reducing exposure to moist environments and chemical irritants may be helpful, these treatments alone have been uniformly unsuccessful. ^, Studies from the dermatologic literature found that topical corticosteroids and even topical tacrolimus are more effective than topical antifungals, implicating the relative importance inflammatory element over the mycological component. ^,

Operative treatment

Eponychial marsupialization is the most common surgical treatment for the chronic paronychium. Under digital block anesthesia and tourniquet control, a crescent-shaped incision is made beginning 1 mm proximal to the distal edge of the eponychial nail fold and extending proximally for 3 to 5 mm. Some authors recommend removal of all thickened tissue. Others have found a 3-mm margin adequate to achieve equal results. The crescent should be symmetrically shaped and extend to the edge of the nail fold on each side ( Fig. 2.6 ). The crescent of tissue is removed down to but not including the germinal matrix. The wound is left open and allowed to drain. If nail deformity is present, removal of the nail has been reported to improve the cure rate and reduce the risk of recurrence. Pabari and colleagues have described elevation of the nail fold, inverting and folding this tissue over a nonadherent gauze, and anchoring the inverted skin proximally with a nonabsorbable suture. Anchoring sutures are removed between 2 and 7 days, and the nail fold is allowed to return to its original position ( Fig. 2.7 ).

Postoperative Management and Expectations

The postoperative dressing is removed at 48 to 72 hours by soaking in 3% hydrogen peroxide solution. The patient is instructed to soak the area three times per day in dilute povidone-iodine solution. This continues until 2 days after all drainage has stopped. Oral antibiotics are given for 2 weeks. If cultures are negative or the organism is not sensitive, the antibiotic therapy is discontinued at 3 to 5 days.

Most chronic paronychial infections resolve with marsupialization. Systemic or topical antibiotics or antifungal agents are often not required. Wound healing by secondary intention occurs over 3 to 4 weeks. Scar sensitivity is more common than in acute paronychia and may persist for several months. Nail deformity is also more common than in treatment of acute paronychia. Six to 12 months of nail growth is necessary before an accurate assessment of residual deformity can be performed. Recurrence rates are higher if the patient does not correct environmental factors or if systemic diseases are not medically controlled. In the event of recurrence, remarsupialization and nail removal should be done.

Clinical Presentation and Evaluation

Felons account for 15% to 20% of all hand infections. A felon is characterized by severe throbbing pain, tension, and swelling of the entire distal phalangeal pulp. The pulp space is exquisitely tender, but the associated swelling does not extend proximal to the DIP flexion crease, unless the joint or tendon sheath is involved. With the progression of swelling and tension, there is compromised venous return, leading to microvascular injury and development of necrosis and abscess formation. There is often a preceding history of penetrating injury, such as a wood splinter, glass sliver, or minor cut. “Finger-stick felons” can be seen in diabetics, who repeatedly traumatize the fingertip for blood tests. Once the felon has developed, the patient may attempt a decompression with a knife or needle. The pain and swelling usually develop rapidly. The expanding abscess breaks down the septa and can extend toward the phalanx and produce osteitis or osteomyelitis, or it can extend toward the skin and cause necrosis and a sinus somewhere on the palmar surface of the digital pulp. If adequate decompression does not occur, the digital vessels will thrombose with resultant sloughing of the tactile pulp ( Fig. 2.9 ; Case Study 2.2 ). Other complications of an untreated felon include sequestration of the diaphysis of the distal phalanx, pyogenic arthritis of the DIP joint, and flexor tenosynovitis, although the last is quite rare.

FLOAT NOT FOUND

Treatment

Treatment of the felon should be directed toward preserving the function of the finger pulp. These functions include fine tactile sensibility and a stable durable pad for pinch. In the early cellulitic phase, it may be possible to treat the felon with elevation, antibiotics, and soaks. Short-term immobilization provides comfort. Some authors recommend surgical drainage only in the presence of abscess. In our hands, surgical drainage is indicated when the pulp is very tender, tense, or fluctuant. The basic tenets of all approaches are to avoid injury to the digital nerve and vessels. The incision should avoid leaving a disabling scar, provide adequate drainage, and elude inadvertent violation of the flexor tendon sheath, which could lead to an iatrogenic flexor tenosynovitis.

Operative treatment

Several surgical incisions have been described ( Table 2.2 ; Fig. 2.10 ); some of these are of historic interest only and are no longer recommended. Surgery may be performed under digital block anesthesia or under general anesthesia. A tourniquet is helpful for visualization. Regardless of the type of incision, surgical decompression requires release of all of the septa, debridement of necrotic tissue, irrigation, and wound management to allow continued drainage of the abscess cavity. To keep the wound open and draining, a gauze wick is placed in the wound. The first dressing change is done at 24 to 48 hours. Authors’ opinions vary as to how long to keep the wound open with a wick drainage. Depending on the severity of infection, 2 to 5 days should be adequate for most cases. Soaking in dilute povidone-iodine solution, as described earlier, is initiated after the first dressing change and continued until wound healing by secondary intention.

TABLE 2.2

Surgical Incisions for the Treatment of Felon

Incision	Advantages	Disadvantages	Comments and Technical Points
A: Fish-mouth incision ( Fig. 2.10A )	None	Risks circulation leading to skin slough; unstable pulp; unsightly scar	No place in treatment
B: “J” or hockey-stick incision ( Fig. 2.10B )	Good for extensive or severe abscess	Incision coming distally into the fingertip can cause painful scar	Adequate debridement and release of septa can be performed without crossing the fingertip (see F)
C: Through-and-through incision ( Fig. 2.10C )	Wide access to all involved septal compartments	Additional wound; superfluous incision that can compromise circulation to the pulp	Initially described with a “J” incision on the ulnar side with a longitudinal counterincision; extension across the fingertip is not necessary; two dorsolateral incisions
D: Volar incision (transverse) ( Fig. 2.10D )	Most direct access to area of abscess; easy to perform; better maintains structural integrity of palmar pad	Palmar scar; higher risk of digital nerve and vessel injury	Incision 4–5 mm made at site of maximal fluctuance; sharp dissection through skin and dermis only, followed by blunt dissection through the pulp; elliptical excision of sinus tract and necrotic tissue (if present)
E: Volar (longitudinal) incision ( Fig. 2.10E )	Same as above; lower risk of digital neurovascular injury	Palmar scar	Same as above; incision should not cross DIP flexion crease
F: Unilateral longitudinal incision ( Fig. 2.10F )			Preferred placement on the ulnar side of the index, middle, and ring fingers and on the radial side of the thumb and small fingers