Advanced Casting Technology™ Foot Impression Techniques for Custom Foot Orthotics

While our lab can fabricate custom foot orthotics from a slipper cast or a foam impression, we prefer to use a weightbearing impression method to capture the plantar shape of the foot. The reason for this is as follows: In casting the foot with plaster, the lateral column is loaded to lock the foot and approximate weight bearing. The technician’s technique can have a great effect on the amount of load applied in this area and consequently can alter the foot shape dramatically. Additionally, the mold must be interpreted in the lab to further reduce the arch height and to allow for foot elongation and splay otherwise the finished device will not be tolerable to the patient. This lab interpretation along with the diversity of casting technique makes the final version of the foot non-reproducible. The same thing can be said of foam impression boxes.

The Advanced Casting Technology™ Impression Method we use captures the uncompensated plantar foot topography in weight bearing. This is done by having the patient stand on the impression pillows with knees flexed. This represents the position of the feet just before ‘toe-off’ during the gait cycle when the foot is in motion towards supination. Once the subtalar joint is aligned, the impression is made using heat-moldable cork. The use of this technique (given the patient’s weight remains constant, pillow density is constant, and proper alignment is achieved), produces a foot shape that will be reliable each time the impression is taken. Consequently the foot model is consistent and reproducible regardless of who takes the impressions and results in a plantar profile very natural to the foot. Our direct experience with over 10,000 patients has demonstrated this consistency. (see results)

The orthotics made from the A.C.T.™ impressions are proven very comfortable and provide excellent control. If patient compliance becomes a problem it can be a sign the arch profile may still be too high. However this rarely happens with the weight bearing model. More often a patient’s whose orthotics had been made from a neutral cast will complain about being uncomfortable with the arch profile (Click here to view "A.C.T.™ Technical Information").