A colleague recently asked whether prefabricated orthoses for plantar fasciitis require a plantar fascia groove.
A plantar fascia groove is used to decrease pressure on a very prominent plantar fascia. I find this accommodation is rarely needed, even when making a custom orthosis. In fact, there are some inherent problems with using a plantar fascia groove because it can cause the orthosis to gap excessively from the arch of the foot.
My preference is that if a plantar fascia groove is necessary, the clinician should add it after the patient receives the orthosis.