The previous forum post on this subject discussed the basics of creating an effective and accurate foot orthotic within the confines of busy clinic practice, with limited time and resources with which to properly assess the patient’s condition and then formulate a treatment plan. One way to simplify the process is to break down the orthotic build into three components; rearfoot, midfoot and forefoot, each component to address any corresponding significant findings of the biomechanical exam and gait analysis.
The major components of a custom orthotic in the rearfoot are the heep cup and the rearfoot post. The heel cup is the concave surface of the orthotic in which the patient’s heel will sit. The heel cup can vary by depth, deeper for additional motion control of inversion or eversion of the calcaneus, shallower to allow better fit within low volume shoes. The shape of the heel cup can be altered by the addition of a heel skive, which is a flattening of the dorsal concave surface of the heel cup either medially or laterally. Generally used to provide additional motion control of excessive heel inversion or eversion without changing the actual angular correction of the orthotic device. The amount of heel skive can vary depending upon the prescriber's preference and the patient’s needs.
The rearfoot post can be either extrinsic (a flat surface added to the plantar aspect of the heel cup), or intrinsic (built into the heel cup of the orthotic frame by removing frame material from the plantar surface of the orthotic frame at the desired angle. Extrinsic posts are generally more controlling than intrinsic posts, but intrinsic posts are preferred when space within the shoe is at a premium, providing a lowered seating of the foot within the shoe. Corrections of zero to 8 degrees in either varus or valgus direction can be incorporated into most orthotic devices. Extrinsic rearfoot posts can also be undercut, so as to be narrower at the shoe/orthotic interface than the width of the heel cup. Extrinsic posts can also be made to allow a rocking motion of the orthotic to occur during the heel contact phase of gait.
Additional corrections can be incorporated into most orthotics depending on the individual clinical need. Full heel cushions, horseshoe pads, heel apertures with and without filler can be made on a case by case basis. Heel lifts can be added to the posts as desired, up to 6mm in height. A heel elevator may be used in certain cases particularly when the orthotic needs to be paired with a shoe or boot with a higher than average heel elevation such as a western boot.
This listing of rearfoot orthotic components is not intended to be totally comprehensive, the options available to modify a custom orthotic are only limited by the clinician’s imagination and ingenuity. The next article in this series will be focused on midfoot considerations in building out a highly effective custom foot orthotic.
