Infection

Signs include redness, tenderness, swelling (often more appar­ent on the back of the hand), lymphangitis — streaks of red running up the arm — and lymphadenopathy (epitrochlear or axillary). Many hand infections will settle within 24—48 hours if elevated, splinted and treated with a best-guess antibiotic. As soon as the signs of inflammation have settled, the hand must be diligently mobilised. If pus appears, it must be drained; the wound should be left open, antibiotics changed according to microbiological advice, and the hand splinted in the Edinburgh position and then mobilised as soon as the inflammation settles.

Acute paronychia

This is the most common infection of the hand, often caused by careless nail trimming or picking the skin around the nail fold (Fig. 30.12). After an initial inflammatory phase, pus is trapped beside the nail. The pus is released by incision on to the nail fold and excision of the outer quarter of the nail.

Chronic paronychia

This appears over several weeks (Fig. 30.13). Rather than a consequence of an acute paronychia, it is usually a chronic fungal infection in those with their hands constantly immersed. Microscopical examination of the scrapings and special fungal cultures will confirm the diagnosis. It may resolve if the hands are kept dry and the nail fold is regularly dressed with antifungal ointment. If this fails, the nail fold is laid open.

Pulp space

Otherwise known as a ‘felon’, this causes severe pain in the finger pulp. Pus is trapped between the fibrous septae which bind the specialised fingertip skin to the underlying bone; the bone of the terminal phalanx can also become infected leading to a sequestrum. An abcess should be drained through an oblique incision over the point of greatest tender­ness. The differential diagnosis is a herpetic whitlow. This is caused by herpes simplex virus and may be found, for example, in dental workers. Small vesicles appear which then become crusty. Surgery should not be performed; it resolves itself over a few weeks.

Flexor tendon sheath infection

There is little spare space within the tendon sheath; an untreated infection rapidly causes adhesions and even tendon necrosis, leading to a stiffs useless finger. The classic signs, described by Kanavel, are a swollen finger held in flexion, with exquisite pain on passive extension and tenderness pre­cisely over the flexor sheath. The usual organism is a Staphy­lococcus or a Streptococcus. The tendon sheath should be promptly irrigated with normal saline through a fine catheter passed into small incisions over the distal and proximal ends of the sheath. The finger must be moved as soon as the signs of inflammation begin to resolve.

  Bites

Serious infection and subsequent loss of function can result from animal or human bites. Human organisms include Eikenella corridens; animal bites include Pasteurella multicodens. Staphylococci are common in both. These organisms are usually sensitive to broad-spectrum antibiotics such as Augmentin. Wounds should be explored under adequate analgesia and a tourniquet. A common injury is over the knuckle when the opponent’s tooth penetrates the metacarpophalangeal joint. The penetration may not be apparent because the four layers (skin, tendon and capsule and synovium) which are injured in flexion close over when the knuckle is examined in extension. The wound must be excised, the joint thoroughly washed out, and the extensor tendon repaired and splinted.

Other infections

Mycobacterial infections

Tuberculosis in the hand may involve the tenosynovium, joints or bone. The most dramatic is a so-called compound palmar ganglion, with synovial swelling both proximal and distal to the transverse carpal ligament. The diagnosis is confirmed by biopsy. Treatment is by synovectomy and prolonged drug treatment.

Pilonidal sinus

A hair implanted in the palm or web space can cause a cyst with recurrent infection (Fig. 30.14). The cyst should be excised.

Orf

Transmitted by sheep, this virus causes red papules which become reddish blue and then grey nodules. The condition resolves after a few weeks.

Palmar space infections

Pus can collect deep to the palmar fascia either side of the septum running down to the third metacarpal. The whole hand is swollen and the palm intensely tender. The infection is drained through a longitudinal incision, great care being taken to avoid damage to the tendons, nerves and blood vessels.

Web space infections

Pus can collect in the potential space surrounding the lumbrical muscles as they pass from the palm, across the deep transverse metacarpal ligament into the extensor mechanism. The swelling in the web space tends to spread the adjacent fingers apart. The pus is drained through a longitudinal incision over the web space, taking care not to damage the nearby neurovascular bundles.