The CarbonEaze insoles come with two different forefoot designs: one is the full width of the forefoot and the other only goes under the big toe and is called the Morton’s extension design. Both designs serve to stiffen the forefoot to make it more rigid with a slight difference. The full width design has the effect of stiffening the entire forefoot whereas the Morton’s extension design does allow more movement across the lateral side ball of the foot and mostly affects motion at the big toe (hallux) joint.
If the symptoms are mostly in the first metatarsophalangeal joint (big toe joint), then you can use either design, however, the Morton’s extension design will allow more normal movement under the lateral or lessor metatarsophalageal joints than what the full width design allows. This Morton’s extension design is more suitable for conditions like osteoarthritis of the big toe joint (hallux rigidus) or turf toe.
If the symptoms are mostly in the second to fifth metatarsophalangeal joint (lessor toe joints) and dorsiflexion of these joint across the ball of the foot is painful, then you are better off with the full width design. These would include conditions like Freiberg’s disease.