Pus in the foot

Foot infections are common, especially in communities where people don't wear shoes, but they are not as common as hand infections. Fine movements are not so important in the foot as they are in the hand, so that infection of the tendon sheaths of the foot is less of a disaster. You must however drain septic arthritis and osteitis, or persistent sinuses may follow.

Some aspects of foot infections are discussed in other chapters[md]osteomyelitis of the calcaneus and talus (7.13), and mycetoma (31.3). Leprosy patients are particularly liable to foot infections, and have their own special problems (30.6).

PUS IN THE FOOT Manage subcutaneous infections (8.2), apical toe space infections (8.3), paronychia (8.4), pulp infections (8.5) and web space infection (8.7) as in the hand. They are all fairly common

ANAESTHESIA. (1) Intravenous ketamine (A 8.1). (2) General anaesthesia (A 10.1). (3) Local anaesthesia is suitable for very localized infections.

For all but the most superficial infections use a tourniquet (3.9), unless the patient's circulation has been impaired by ischaemic disease.

DEEP INFECTION OF THE PLANTAR SURFACE OF THE FOOT is usually due to an injury, such as a thorn, which has penetrated deeply.

If you suspect a foreign body, incise the abscess, search for it and clean out the cavity thoroughly. Leave the wound open sufficiently for it to heal up from below.

If infection is spreading on to his foot and up his leg, explore and drain the lesion, and give him an antibiotic suitable for the staphylococci in your area. As in the hand, rapidly spreading infections are likely to be due to haemolytic streptococci (8.12).

INFECTIONS OF THE DORSUM OF THE FOOT present early, and can usually be drained through a small incision using local anaesthetic infiltration.

INFECTIONS OF THE TENDON SHEATHS are uncommon except in leprosy, and when there is a foreign body involving the tendon sheath. Incise over the infected part, drain, and leave the wound open. In a late case you may need to remove necrotic tendon.

SEPTIC ARTHRITIS can involve any joint.

If an IP joint is involved, open it widely through a longitudinal incision on the dorsal surface to one side of the extensor tendon. Clean it out and leave it open to drain.

If an MP joint is involved, approach it either from the dorsal surface (open it from just to one side of the extensor tendon), or from the plantar surface. Open the wound widely and let it drain. Wounds in the plantar surface heal well.

If other joints are involved, approach them from the side where the bone is nearest to the surface. Clean the joint out well and leave it open.

OSTEITIS. Give him an antibiotic (2.9) and remove necrotic bone as necessary in chronic cases.

If his phalanges are involved, drain the infection and it will probably settle. Osteitis commonly follows infection in the soft tissues, especially infections of the pulp of the distal phalanx.

If his metacarpals are involved (uncommon), he may have: (1) Osteomyelitis following an injury. Approach the bone through a dorsal incision and reflect his extensor tendons. Drain the wound and remove necrotic tissue. Loss of one or two metacarpals is of little functional importance. (2) Acute haematogenous osteomyelitis. If he is under 10 years, an antibiotic alone may be adequate. If he is over 10, his bone will also need drilling. (3) Chronic haematogenous osteomyelitis. He presents with persistent pain and sinuses. Remove necrotic bone, without waiting for the formation of an involucrum.

CAUTION ! If his foot becomes infected without obvious reason look for: (1) A foreign body. (2) Leprosy (30.5). (3) Diabetes. (4) Ischaemia (uncommon in most of the developing world: feel his dorsalis pedis and his posterior tibial pulses).

POSTOPERATIVELY, stop him bearing weight. If he has a severe infection apply a plaster gutter splint to hold his foot in neutral (69-1). This will reduce pain and ensure that his foot is in the best position if it does becomes stiff.

9 Methods for abdominal surgery