This is the commonest hand infection[md]pus more often gathers in the finger tips than anywhere else in the hand.
The pulp of a finger is divided into many small fatty compartments by strands of fibrous tissue which run from the skin to the periosteum of the terminal phalanx. A sheet of fibrous tissue runs from the distal flexor crease to the periosteum, and so separates the pulp space from the rest of the finger. There is little room for swelling, so that infection causes a throbbing pain early. Pus from a patient's pulp can track: (1) through to the skin outside, or (2) through the periosteum, causing osteomyelitis of his distal phalanx. Its epiphysis is supplied by a separate artery, so this usually survives the infection.
PULP INFECTION For the general method for hand infections, see Section 8.1. Tenderness is maximal over the ball of the patient's pulp.
If the abscess is in his distal pulp, and is already pointing to its centre, drain it by making a cross-shaped incision, or by removing a small circular or elliptical segment of skin over the abscess, as in B, to E, Fig. 8-3. The incision will heal to leave a small punctate scar.
If the abscess is deep, is not pointing, and appears to extend into several compartments, make a J-shaped lateral longitudinal incision close to the bone, and not more than 3 mm in a palmar direction from the free edge of his nail. Keep your knife away from his palmar skin, as in N, and O, Fig. 8-2, and avoid the tip of his finger. Remove pus and slough, and lightly pack the wound with gauze. Don't suture the incision. Change the dressing after two days.
If the infection has been neglected, so that the whole terminal segment of his finger is swollen, continue the incision over the end of his finger and round to the other side. Divide the vertical septa and let the wound gape open. Dress it as above.
CAUTION ! (1) Don't incise the tips of his fingers, or the palmar surfaces of his distal phalanges, unless pus is already pointing there, because pressure on the scar may be painful. (2) Any incision, other than those described, is likely to be painful, especially if you carry it towards the palmar surface. (3) Don't damage his periosteum. (4) Check for a collar-stud abscess (easily seen if you have used a tourniquet to give you a bloodless field).
DIFFICULTIES. [f41]If his infected FINGER CONTINUES TO DISCHARGE for some weeks, suspect osteomyelitis (8.16D). X- ray it. When X-rays show that the sequestrum has separated, remove it. If he is a child, his distal phalanx will regenerate under its periosteum. If he is an adult, he will be left with an ugly curved nail and a short terminal phalanx.
Fig. 8-3 PULP INFECTIONS. A, a neglected pulp infection. Much of the patient's finger tip is already destroyed, and pus is starting to discharge spontaneously. B, [f10]if pus is already pointing, [f11]make a cross-shaped incision. C, swab away the pus. D, remove any dead skin. E, open up the infected pulp compartment. If it is not pointing and several spaces are infected, open up his finger tip from the side as in N in the previous figure.