Lister corns are found on the inside and outside of the nail bed, typically on the 5th toe. Lister corns are often described by the patient as having a 'second toe nail' on the toe. This 'second toe nail' is actually hard callus that resembles nail. Pain is described with direct pressure to the corn by shoes. Lister corns are named after the father of modern surgery, British surgeon Joseph Lister (1827-1912).
Corns form by direct pressure against the skin. The reaction of the skin is to protect itself by forming more skin. Initially this protective layer of skin is helpful, but as it thickens this protective layer of skin will increase the pressure applied to the underlying soft tissue and bone and become painful. A Lister corn is created by direct pressure to the skin and bone adjacent to the toe nail.
The bone of the toe is partly responsible for the formation of a Lister corn. The bone in the tip of the toe is called the terminal phalanx and is shaped a little like a Mexican sombrero with the tip of the hat pointing to the tip of the toe and the brim of the hat flaring out at the base of the toe nail. The brim of the hat can create a prominent bone spur. When direct pressure is applied to the outside of the toe (lateral aspect) by the shoe, we'll develop a Lister corn on the outside of the toe. When direct pressure is applied to the inside (medial aspect) of the toe by the adjacent toe, we'll develop a Lister on the inside of the toe.
Lister corns are unique in that they can also form in the absence of shoe pressure. Many of us have toes that roll to the side so that the nail doesn't face up, but rather out to the outside of the foot. This digital position is called varus rotation of the toe. Varus rotation of the toe rolls the bone in the tip of the toe so that the brim of the hat is out of the way of the shoe, but now the brim is in direct and constant contact with the floor. Also, in cases of varus rotation of the 5th toe, the 4th toe will tend to rest on top of the 5th toe resulting a medial Lister corn. In cases of fixed varus rotation of the 5th toe, it's not unusual to see a Lister corn on both the outside (lateral aspect) and inside (medial aspect) of the toe.
Causes and contributing factors
Contributing factors to Lister corns include varus rotation of the 5th toe and tight shoes.
The differential diagnosis for Lister corns includes;
Lister corns can be prevented by wearing shoes with a wide, round toe box. A wide toe box will decrease direct pressure to the bone spur on the terminal phalanx. Periodic trimming of the callus is helpful to relieve pain. Callus cream is helpful to soften the corn prior to trimming. Padding of a Lister corn can be accomplished in a number of different ways.
Recurrent Lister corns of the medial aspect of the toe can be treated surgically by filing the spur on the medial aspect of the terminal phalanx. This procedure is called a condylectomy. The incision for a condylectomy is very small and often does not require a suture closure. A condylectomy can be performed in an office or hospital setting. The procedure can be completed in a matter of minutes and requires only mild sedation and the use of a local anesthetic. Following a condylectomy, most patients are able to return to showers and regular shoes within a matter of days.
Lateral Lister corns do not respond as well to a condylectomy. To surgically correct a lateral Lister corn, a terminal Symes procedure is recommended. A terminal Symes procedure involves complete resection of the terminal phalanx and nail. Suture closure is required. A terminal Symes procedure is performed in a hospital or surgery center with sedation and a local anesthetic. Patients are ambulatory immediately following a terminal Symes procedure and may return to regular shoes in 2-3 weeks.
When to contact your doctor
Conservative care that fails to heal Lister corns should be evaluated by your podiatrist.
References are pending.
Author(s) and date
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Cite this article as: Oster, Jeffrey. Lister Corn. http://www.myfootshop.com/article/lister-corn
Most recent article update: December 23, 2015.
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