Flatfoot could cause problems in the feet because it makes the foot more flexible.  Conditions such as bunions and hammertoes, as well as plantar fasciitis, ankle, leg and knee pain can develop as a result.  Muscles are imbalanced and some have to work harder than others.  Rigid orthotic support works to put joints in better position, and decrease the stress on certain tendons and ligaments.  For more information, please click this link.