There has been some confusion, Davis states, with respect to recognizing what constitutes a true prescription custom foot orthotic as opposed to a prefabricated support. His website was written to help explain the differences between the real thing and and devices which may be marketed with words such as "custom" by retail outlets.
The most important thing to remember is that prescription custom foot orthotics involve several steps:
1) A medical exam, specifically a biomechanical exam to determine foot function.
2) Impressions or molds of the patient's feet made by the doctor who attempts to capture the corrected position of the feet. That cannot be performed by having a patient stand in a foam box but utilizing casting material placed over the feet while the doctor manipulates the feet to the proper position.
3) The doctor sends the foot molds and prescription to an accredited foot orthotic laboratory that creates a model of the feet to which it builds the prescription orthotic.
Davis states that he frequently recommends prefabricated or off the shelf orthotics when patients do not require custom prescription devices but it is important to understand the difference between the two.