A ProLab client asked what type of orthotic should be used for fifth metatarsal head calluses. There are number of pages on this website that deal with the most effective orthotic prescription for metatarsal head calluses, but today I wanted to deal with what cast fill should be used for a fifth metatarsal head callus.
This is somewhat complicated since you want the orthosis to conform close enough to the arch of the foot that you transfer maximum pressure off of the fifth metatarsal head but not so much that the orthosis supinates the foot and pushes the foot onto the lateral column and fifth metatarsal head.
My recommendation is to use a minimal cast fill with one or two degrees of inversion. This device should conform very closely to the arch of the foot and effectively transfer pressure from the fifth metatarsal head onto the arch. You do run the risk that it could push a little bit too far. However, that is an easy adjustment. If that occurs simply grind the arch of polypropylene orthoses a little thinner to make it more flexible. If it is graphite orthoses, you would have to heat adjust the device. Either way, these are fairly easy modifications.