How does a tailor's bunion cause a soft corn?
One of the greatest things about medicine is that you're always learning. This week I saw four different cases of interdigital soft corns called helloma molle. These little areas of callus are often found in the space between the 4th and 5th toes and are often confused with a case of interdigital athlete's foot. But prior to this week, I hadn't realized the relationship between soft corns and a condition of the 5th metatarsal called a tailor's bunion.
Take a peek at our knowledge base article on tailor's bunions and you'll see that the primary contributing cause of a tailor's bunion is the deviation of the 5th metatarsal away from the foot. This bowing of the 5th metatarsal creates the bump we know as a tailor's bunion.
So what's this have to do with soft corns? In each of the four soft corn cases that I saw this week, each had a significant tailor's bunion. As the 5th metatarsal bows away from the foot, the long flexor tendon will begin to pull the toe in an eccentric manner. In fact, in each of these cases, the long flexor tendon was actively pulling the 5th toe against the 4th toe resulting in the recurrent pressure that causes a soft corn.
OK, I realize that this information isn't going to change the world, but honestly, it is a biomechanical characteristic of the foot that contributes to soft corns that I had never considered. 30 years of practice to understand this? I'm still learning.
As a boy I overheard a couple of fellows talking about motorcycles. One said that the day you think you've mastered riding a motorcycle, that's the days you ought to quit riding. And the same holds true for the practice of medicine. I learned something new this week. I guess I'll stick with this for a while.
Jeffrey A. Oster, DPM