Onychocryptosis (ingrown nail) is a condition that can affect one or both borders of any nail. Typically it involves the big toe. The condition can result from trauma to the nail plate or matrix (nail root cells), fungal infection (onychomycosis,), or over-zealous or improper trimming of the toenail. It may lead to severe pain, swelling, or infection (paronychia). Pain is caused by the nail growing either medially or laterally (depending on which nail border is involved) into the periungual soft tissue, acting like a foreign body. Secondary dermatologic changes may also occur, such as a pyogenic granuloma or chronic granulation tissue (“proud flesh”).
The condition can be treated by wedge resection (under anesthetic block) of the offending border or total nail avulsion if both borders are involved. A new nail will return after six to nine months. If the condition is chronic by history, or if recurrence takes place, wedge resection with matrixectomy should be considered. A matrixectomy (destruction of nail root cells) can be performed either by chemical (phenol) or surgical methods. Patient factors combined with the history and physical help determine the appropriate method for each patient.