Consider a felon's origin. If it begins in the subungual space, its initial surgical treatment should include exposing, draining, and cleaning that space. (“Sometimes, It's Subungual,” The Procedural Pause blog by James R. Roberts, MD, and Martha Roberts, ACNP, CEN; http://bit.ly/1cLTbrl.)
The long-held belief is that felons begin in the pad, and its appearance that is responsible for that belief. On examination of the involved digit, the dorsum typically appears normal or nearly so, and the pad is swollen and red. We have accepted Dr. Allen B. Kanavel's speculation for 100 years that the infection is introduced by an unnoticed prick. Let us examine that speculation.
Not only must the prick be unnoticed but any soreness subsequent to the prick must also be unnoticed. In addition, the wound in the skin must be invisible or it too must be unnoticed. The point of this is not to deny the possibility that unnoticed finger pricks may cause some felons, but that accepting unnoticed finger pricks as the primary cause of felons requires a reliance on a unrealistically consistent obliviousness. Another consideration is that no one has any idea which agents so consistently deliver these pricks to leave no trace except for deposits of bacteria. Septic emboli also should be mentioned as a possible cause of felons.
We are left with the dorsum of the digit. Paronychia and eponychia are common manifestations of the digit's susceptibility to infection occurring at the junction of the nail and its soft tissue. Could there be another but far less common manifestation of that same susceptibility? The sequence could begin with bacteria entering the subungual space. (?I suspect the entry site is usually at the hyponychium because nail fold involvement so infrequently accompanies felons.) Infection ensues. Lymphangitis and cellulitis develop and then envelop the pad. The infection progresses.
Still, there is the normal appearance of the dorsum of the digit. Does the adage “appearances can be deceiving” apply to felons? If so, the felon has fooled us for centuries.
Edward G. Rupert, MD
Dr. Roberts responds: Interesting concept on the management of a felon; I had not considered that approach previously nor has it been suggested to my knowledge. The felons I have dealt with don't seem to be drainable simply by removing the nail; they are deep in the fat pad. Do you have other experience?