If you have ever been fitted for shoes, you are probably familiar with a Brannock Device. It’s a tool that measures the length and width of your feet and corresponds those dimensions to shoe sizes. As a kid, every year around this time, I would get my feet measured to see what size shoes I needed for the school year.

While the Brannock Device has been around for nearly a century and is still the most commonly used tool for fitting shoes, there is a much simpler and more effective way to ensure proper fit. This technique, called the Insole Test, was developed by an intuitive podiatrist named Dr. Ray McClanahan. He is a proponent of restoring feet to their natural shape, where the tips of the toes are the widest part. He has become dissatisfied with modern footwear, which often constricts the toes rather than allowing them to spread naturally. The Insole Test ensures that the shoe will fit the shape of the foot, especially the toes.

You would perform the Insole Test as follows: Take the insole out of the shoe you want to buy and stand on it in full weight bearing. Splaying your toes while standing on the insole ensures the shoe can accommodate your entire foot in its most functional state. If your foot stays within the confines of the insole, the shoe will support your natural foot shape. If your toes spill over the side of the insole, your foot will be placed in a compromised position inside the shoe. Repeat the test with the opposite shoe and foot.

The Insole Test is especially valuable when considering the long-term effect that shoes can have on our feet. We have known for many years that shoes can change the shape of our feet. Nearly 150 years ago, a German medical doctor named Hermann Meyer published a book called “Why the Shoe Pinches: A Contribution to Applied Anatomy.” In it, he points out that when our feet are cramped for room in the shoe, they gradually take on the shoe’s shape.

The long-term effect of wearing poorly fit shoes is an increased risk of developing foot deformities like bunions. Ideally, your big toe should be aligned with a bone in your foot called the first metatarsal—the long bone that forms the inner aspect of your foot. Bunion formation often occurs when the big toe is pushed toward the smaller toes over time, as is the case with narrow shoes.

When you look at the shape of most shoes, it’s no surprise that bunions and other foot deformities are so prevalent. By using the simple yet powerful Insole Test when selecting shoes, you can be proactive in preventing these deformities and preserving the health of your feet.

Dr. Jordan Duncan is from Kitsap County and writes a monthly online health column for Kitsap News Group. He is the owner of Silverdale Sport & Spine.