Problem: Hand infections include superficial infections, infections of the nail, infections of the tendon and tendon sheath, infections of the deep spaces of the hand, septic arthritis and osteomyelitis.

Etiology: Hand infections usually result from some sort of injury, most commonly a laceration or an animal bite. Most patients recall an inciting event that resulted in the inoculation of bacteria into the hand. Infections of the nail and of the nail folds can result from a nail deformity.

Clinical: A thorough history of an infection includes determination of onset, duration, recent trauma, and systemic symptoms (eg, fever, chills, diaphoresis). Most patients present with a 2- to 3-day history of cellulitis; swelling; and occasionally, drainage.

Review of past medical history is important, because patients with diabetes or an immunocompromised status require more aggressive treatment and closer observation. Obtaining the patient's immunization history is also important. If the patient's tetanus status is unknown or out of date, administer tetanus prophylaxis.

Some early infections can be managed with antibiotics. Antibiotic treatment is appropriate for cellulitis. Oral antibiotics are usually the appropriate first line of treatment. However, persistent cellulitis or infections in immunocompromised patients should be treated with intravenous antibiotics until the cellulitis resolves. Then, completion of a course of oral antibiotics is appropriate.

If any signs of fluctuance or purulent wound drainage are present, incision and drainage is necessary. Furthermore, cellulitic infections that are unresponsive to antibiotics may require surgical exploration. Surgeons undertaking incision and drainage should be familiar with the anatomy of the hand, including the anatomy of the nail, the course of digital neurovascular bundles, and the deep spaces of the palm. Furthermore, appropriate management requires close postoperative monitoring.

Relevant Anatomy: A brief review of the most common hand infections by anatomic location follows.

Acute paronychia involves the soft tissue around the fingernail and usually results from the inoculation of bacteria (most commonly Staphylococcus aureus) into the paronychia tissue from nail trauma or nail manipulation. Drain superficial abscesses with limited incision and drainage. Obtain cultures if possible. If the infection resulted from an ingrown nail, excision of the radial or ulnar one fourth to one half should be performed at the time of incision and drainage. Infections involving the eponychial fold can be drained by elevating the eponychium, either sharply or with a freer or elevator. The patient should receive a course of oral antibiotics with good staphylococcal coverage (eg, Cefazolin intravenously or cephalexin orally). In addition, the patient should soak the finger in antiseptic solution 2-3 times a day.

Chronic paronychia usually is caused by Candida albicans and occurs most commonly from chronic immersion in water (as in dishwashers), prior trauma, or nail defects. Treatment with topical antifungal agents and behavior modification is occasionally successful. Excision of a portion of the nail or removal of the entire nail may be necessary.

A felon is a subcutaneous abscess over the distal pulp of a digit or thumb. Felons usually result from a penetrating injury. The pulp contains multiple compartments separated by fibrous septa that make infections in this area complex. Surgical drainage is necessary when an area of palpable fluctuance is present. Use of several incisions has been described for drainage. However, the preferred incision is radial or ulnar longitudinal. Incisions directly over the finger pad or tip are avoided. Also, subcutaneous septa should be broken up to drain all areas of infection, and the wound is left open. After drainage, warm antiseptic soaks and oral antibiotics are administered. The antibiotic is based on the nature of the infection. Parenteral antibiotics should be considered in patients with diabetes or immunocompromise. Persistent chronic paronychial infections may also require intravenous antibiotics.

Deep space infections are possible. The 2 deep spaces in the palm are the midpalmar space and the thenar space. Infections in these areas usually result from injuries such as bites or puncture wounds. These infections may cause cellulitis, fluctuance, or pain. In addition, the second, third, and fourth web spaces are potential sites for infection. Web space infections can spread from the palmar subfascial space in a dorsal direction, forming what is commonly referred to as a collar button abscess. On examination, patients typically have pain, swelling and fluctuance on the palmar or dorsal web-space surface.

Lab Studies:

• CBC: An elevated white blood cell count can indicate the presence of infection. In the case of particularly severe infections, it may provide a measure of the patient's progress.

• Prothrombin time (PT) and activated partial thromboplastin time (aPTT): Obtain these results prior to surgical treatment in patients who are receiving long-term anticoagulant therapy.

• Glucose level: Check glucose levels in all patients with a history of diabetes. In active infections, blood glucose levels are often elevated and difficult to control. Furthermore, blood sugar control is important for wound healing. In addition, check glucose levels in any patient with a history of frequent or particularly severe infections to rule out occult diabetes.

• Chemistry panel: In general, check the chemistry panel of patients who give a history of dehydration (secondary to vomiting or sepsis). Check the chemistry panel of elderly patients prior to surgery.

• Erythrocyte sedimentation rate (ESR): The ESR is elevated in cases of septic arthritis and osteomyelitis. However, patients with inflammatory arthritis may have elevated ESRs without infection.

• If septic arthritis is in question, a joint aspirate should be sent for Gram staining, culturing, and sensitivity testing. In addition, cell count assessment, glucose and protein level determination, and crystal analysis help in distinguishing between an infected joint and a joint with inflammatory arthritis or gout/pseudogout.

Imaging Studies:

• Plain radiographs (3 views of the hand) are important to rule out foreign bodies; fractures; and subcutaneous air, which could indicate gas gangrene or acute or chronic osteomyelitis.

• MRI may be helpful in assessing soft tissue abscess and osteomyelitis.

• Ultrasonography may reveal soft tissue abscess.

• Bone scanning, indium-111 studies, or CT scan may be useful in evaluating osteomyelitis.

Medical therapy: A few important guidelines assist in the management of hand infections. First, cellulitis must be treated with antibiotics. Most hand infections are caused by S aureus, and therefore, a first-generation cephalosporin (eg, cephalexin) is usually the first drug of choice. However, the potential exists for infections with different organisms. In fact, several community-acquired methicillin-resistant staphylococcal infections have been reported recently.

Animal bites require bacterial coverage particular to the offending animal. Human bites require coverage for Eikenella corrodens. Penicillin and a first-generation cephalosporin are appropriate choices. Cat bites require coverage for Pasteurella multocida. Appropriate antibiotics include ampicillin/sulbactam administered intravenously or Augmentin given orally. Usually, oral antibiotics are sufficient as initial treatment. Many medical professionals recommend initial limited wound irrigation in the emergency department or in the clinic. Consider intravenous antibiotics in patients in whom cellulitis fails to resolve with oral antibiotics. In all cases, final antibiotic coverage should be guided by culture and sensitivity results. Initially treat patients with a history of immunocompromise (including those with diabetes) with intravenous antibiotics.

Fungal infections can occur in or underneath the skin. Cutaneous fungal infections, or tinea, are treated with topical agents such as miconazole or clotrimazole. The most common subcutaneous infection is sporotrichosis. Sporotrichosis can appear with an ulcerative lesion, along with lymphadenopathy. Gardeners are most commonly infected. Oral itraconazole for 3-6 months is the current recommended course of treatment. Fungal abscesses or disseminated fungal infections can occur and are usually found in immunocompromised patients.

Preoperative details: Prior to surgery, obtain a thorough history, and perform a thorough physical examination. The operating surgeon must counsel each patient about the appropriate risks and benefits of each procedure. Furthermore, consent for sufficient latitude in performing the procedure (eg, possible amputation) is necessary. Patients should always be preoperatively informed that further operations may be necessary.

Intraoperative details: In the operating room, perform all explorations and debridements under tourniquet control. The extremity should be exsanguinated by gravity. Administer a dose of perioperative antibiotics because of the likelihood of a transient bacteremia after debridement. Obtain cultures prior to the administration of antibiotics.

Intraoperative cultures should include tests for aerobic and anaerobic, fungal, mycobacterial, and atypical mycobacterial organisms. Debride all devitalized tissue, and thoroughly irrigate all wounds. Treat larger wounds with pulse lavage and antibiotic irrigation. Repeat exploration and a second operative irrigation and debridement are necessary for certain wounds.

Flexor tenosynovitis

At the time of the operation, an incision is made in the distal area of the palm over the proximal end of the flexor sheath. The sheath is incised, and the presence of cloudy fluid or pus in the sheath is a clear indication of tenosynovitis. A second midaxial incision is made distally in the digit to provide access to the distal end of the tendon sheath. An irrigation catheter is placed through the sheath, and continuous irrigation of the sheath (usually with saline or antibiotic solution) is performed for 48 hours.

Be cognizant of digital swelling due to overly aggressive irrigation. It is possible to cause digital necrosis. If signs of infection have improved, the drainage system can be removed, and the patient should receive a course of antibiotics with elevation of the affected area.

Deep palm and web space infections

The incision should be centered over the area of fluctuance. Incisions can be made along palmar creases when possible. In the case of deep space infections, wide exposure is important. The palmar fascia is incised, and the common digital nerves and vessels should be identified and protected when possible. A palmar and dorsal incision may be necessary, particularly in the case of collar-button abscesses.

Septic arthritis

Arthrotomy is necessary to adequately treat septic arthritis. For the MCP joint, a dorsal incision can be used. The extensor mechanism is split in the midline, and the joint capsule is incised. In the case of proximal IP joint infections, a dorsal incision can be used, but when dividing the extensor tendon one must be careful to preserve the central slip when dividing the extensor tendon. Alternatively, a midaxial incision can be made. The joint is entered by incision of the accessory collateral ligament.

The joint space must be copiously irrigated, and the fibrinous and synovial debris is debrided. The wound can be packed to allow for continuous bedside irrigation, or, if joint debridement has been adequate, the wound can be loosely closed.

Osteomyelitis

In cases of chronic osteomyelitis, surgical debridement is required. The sequestrum or devitalized bone must be removed. Similarly, in cases of acute osteomyelitis, debridement of the denuded bone is important for obtaining microbiologic cultures and for treatment. Once acute and chronic infections have been resolved, bony reconstruction may be necessary.

Postoperative details: Immobilization, with splinting of the hand in the position of safety (wrist extension of 15-30°, MCP flexion of 70-90°, and IP extension), is important in reducing joint contractures. Furthermore, elevation is a critical aspect of hand infection management. Often, adequate elevation and immobilization require the patient's hospitalization. Once the infection resolves, patients should begin early mobilization therapy. The patient should begin range of motion exercises and be seen by a hand therapist as soon as possible to minimize postinfection stiffness.

Follow-up care: Patients require close follow-up for the first several weeks after the infection. The surgeon should remain vigilant for any recurrence of infection and for appropriate compliance with wound care and hand therapy.

Most complications from hand infections result from inadequate treatment. Inadequacies in treatment can be life-threatening in patients who are immunocompromised. Joint contracture from prolonged immobilization can be functionally devastating.

Recurrent infections or polymicrobial infection of the hand frequently complicates the care of the immunocompromised patient.