The rigid carbon fibre insoles or inserts serve to make the shoes or footwear more rigid, particularly across the ball of the foot. They are indicated in conditions in which dorsiflexion of the metatarsophalangeal joint in the ball of the foot is painful. By stiffening the shoes or making them more rigid these insoles restrict that motion and reduce the symptoms.
Some of these symptoms include hallux rigidus (osteoarthritis of the big toe joint), osteoarthritis in the midfoot joints, turf toe (traumatic flexion injury of the big toe joint) and Freiberg”s disease (most commonly affects the 2nd joint) as well as a number of others.
One way to tell if you think your problem might benefit from these inserts is how do you feel when you wear a more rigid/inflexible shoe versus one that is less rigid/less flexible? If you feel better in the more rigid shoes, then you will probably benefit from these types of flat rigid inserts.