Infection of the hand is frequently limited to one of several well-defined compartments :under the nail fold (paronychia) ;the pulp space (felon) and subcutaneous tissues elsewhere ;tendon sheaths; the deep fascial spaces; and joints. Usually the cause is a staphylococcus which has been implanted by fairly trivial injury. However contaminated cuts, with unusual organisms account for about 10% of cases.
Pyogenic granuloma
Pyogenic granuloma is a misnomer for an exuberant outgrowth of granulation tissue at sites of previous trauma. The lesions are highly vascular with a thin epithelial cover and are friable, bleed easily, and can grow rapidly. They occur most commonly on the fingertips and respond to either curettage or simple excision.
Paronychia
Paronychia refers to infection of the lateral nail folds and usually results from a penetrating injury. The most common causative organism is staphylococcus aureus.
Treatment for early cases is with antibiotics, preferably a penicillin in combination with a beta-lactamase inhibitor such as sulbactam or clavulanic acid. Once an abscess develops, surgical drainage is required ,by making a longitudinal incision just lateral and parallel to the nail fold; however, recent recommendations are to merely remove the nail and let the pus drain out from under the nail fold.
Felon
A felon is an abscess of the pulp space and usually accompanies paronychia. Because the pulp space contains rigid fibrous septa fixing the skin to the periosteum of the distal phalanx, collections in this region can lead to a build-up of high pressures that can be severely painful. Appropriate treatment is surgical incision and drainage of the abscess followed by appropriate antibiotics. Complications include septic tenosynovitis, skin necrosis, and osteomyelitis of the distal phalanx.
Suppurative tenosynovitis Acute suppufative tenosynovitis most commonly affects the flexor tendon sheaths. They usually arise after penetrating trauma and are caused by Stapbytococcus aureus. four cardinal signs in the digit: a fusiform swelling, a flexed attitude, tenderness over the tendon sheath, and pain on passive extension. Early cases may respond to nonoperative treatment, including elevation, warm soaks, and intravenous antibiotics. Unresponsive or late cases require surgical drainage and the flexor retinaculum is opened through two separate incisions proximally at the level of A1 pulley and distally at the level of A5 pulley.continuously irrigated with isotonic saline or lactated Ringer s solution for 36 to 48 hours. Antibiotics are required for at least I or 2 weeks. More severe
infections or a delay in treatment may lead to necrosis of the tendon sheath, osteomyelitis, and abscesses. These are best treated by thorough d6bridement through an extensive exposure.
Chronic tenosynovitis is usually of a granulomatous type and is caused by Mycobacteriurt tuberculosis, atypical mycobacteria, or fungi. Treatment includes adminiy tration of appropriate antimicrobial agents combined with surgical excision of the involved synovium. Chronic infective synovitis needs to be dffierentiated from other causes of chronic granulomatous synovitis, such as sarcoidosis and amyloidosis.
Deep space infections
Kanavel described fascial spaces in the hand where infec tions tend to localize. There are three palmar spaces lying deep to the palmar aponeurosis, namely, the midpalmar, thenar, and hypothenar spaces. A fourth space, termed Parona s space, is in the distal forearm and ovelies the pronator quadratus muscle. On the dorsal aspect of the hand, the subaponeurotic space lies deep to the extensor tendons over the dorsal interosseous muscles.The large thenar&midpalmar fascial spaces may be infected directly by penetrating injuries or by secondary spread from a web space or an infected tendon sheath .clinical signs may be misleading: the hand is painful but because of the tight deep fascia,there may be little or no swelling in the palm while the dorsum bulges like an inflated glove.there is extensive tenderness and the patient holds the hand as still as possible.As with other infections ,splintage and i.v antibiotics are started as soon as the diagnosis is made.for drainage ,an incision is made directly over the abscess (do not cross flexor creases )and sinus forceps inserted.If the web space is infected,it too should be incised.a thenar space abscesscan be approached through the first (web space)but do not incise in the line of the skin fold) or through separate dorsal and palmar incisions around the thenar eminence .great care must be taken to avoid damage to the tendons, nerves and blood vessels.the deep mid- palmar space(which lie between the flexor tendons and the metacarpals) can be drained through an incision in the web space between the middle and ring fingers, but wider exposure through a transverse or oblique palmar incision is better. above all do not misled by the swelling on the back of the hand into attempting drainage through the dorsal aspect. occasionally deep infection extend proximally across the wrist causing symptom of median nerve compression,pus can be drained by antromedial or anterolateral approaches ; incisions directly over the flexor tendons and median nerve are avoided .operation wounds are either loosely stitched or left open. bulky dressings and saline irrigation are employed more or less as in tendon sheath infection Septic arthritis
pain,swelli ng andredness are localized to a single joint and all movement is restricted.lymphangitis and or systemic features may help to differentiate from gout and joint aspiration may solve the case.if the inflammation does not subside within 24 hrs or there are overt signs of pus open drainage is required.for the interphaangeal and thumb metacarpophalngeal joints , mid- lateral incision is recommended.for the other metacarboph. Jointsand the wrist , dorsal incisions are better.the wounds are left open to heal by secondary intention.copious splinting,the hand in position of safety for 48hrs,then movement is encouraged.
Herpes Infection
Herpetic infection or "whitlow,, of a digit is caused by the herpes simplex virus and is frequently seen in health care personnel in which the source is usually orotracheal secre_ tions of patients. The organism incubates for 2 to 14 days before forming fluid-filled vesicles on the fingertip. Theie lesions can sometimes mimic paronychia or felons. The diagnosis is made from a potassium hydroxide prep and Tzanck smear. Clinically, herpetic infections must be differentiated from bacterial infections. Herpetic infections are self-limiting, and treatment is nonoperative. Surgical incision and drainage can lead to systemic involvement and possible viral encephalitis.
Verruca Vulgaris
Vemrca vulgaris are viral warts and occur usually on the digits especially in the nail bed region. They are treated most effectively by coagulation, curettage, or excision. Recurrence is not uncommon, especially in the region of the nail bed.
Infection of the hand is fairly common and assumes significance because of the severe functional compromise that may result from improper or inadequate treatment.
Bites
Animal and human bites are quite common on the hand. Of them, human bites carry the worst prognosis. Human bites are contaminated by mixed oral flora and if untreated can lead to severe infection with rapid destruction of local tissue. Common organisms infecting human bites
are Stapbylococcus, Streptococcus, Bacteroides, and Eikenella corrodens. Most human bite injuries on the hand occur when an individual strikes another person in the mouth with a clenched fist. A tooth produces a puncture wound that may even penetrate into the MCP joint.
Clinical examination should focus on the possibility of extensor tendon injury and joint penetration. Surgical exploration, debridement, and lavage are mandatory in the treatment of these injuries. Human bite wounds should not be closed primarily and are treated with penicillins or cephalosporins after surgery.