By now you have input your patient details and foot model information into the Foot ID Pro when placing a new order, and figured out which foot model design you wish to have your orthotic created from. Now we move down the “Congruency” column to “Fat Pad Expansion-widen heel cup”, then “Orthosis Contour”, “Arch Height”, ”Fat Pad Expansion-widen lateral heel cup” and “Widen Entire Foot Model”. All of these options are intended to create a functional and comfortable full weight bearing orthotic device which was created from a non-full weight bearing model, preferably a sub-talar neutral position impression which captures rearfoot and forefoot deformities, if present. What is not present in the impressions in many cases, is the effect of ground reactive force on the configuration of the foot during standing and walking, usually some flattening and widening, and this must be evaluated, estimated and simulated within the final product.
There are two options here for widening the inner circumference of the heel cup of the orthotic device, namely “fat pad expansion-widen heel cup” and “fat pad expansion-widen lateral heel cup”. The human heel has a special dense layer of fibro-adipose tissue beneath the Calcaneus which absorbs the shock of heel strike during gait, and cushions the heels in a static stance. The reactive force from the ground upward against this fat pad will cause flattening and widening of the fat pad, much like radial tires on a sports car. The amount and thickness of this fat pad varies considerably from one person to the next, and if not accounted for with the shape of the heel cup of the orthotic will cause undue pain and pressure along the rim of the patient's heel and may even prevent the patient from wearing the orthotic device comfortably. Usually we want to expand the heel cup on both the medial and lateral sides, however, sometimes maintaining the non weight bearing shape of the medial side of the heel will allow the shock absorbing quality of the lateral heel to be maintained, yet allow pronation resistance control of the medial side to also be maintained. Heel pad expansion can be varied from 1.5 mm per side up to 3 mm per side (6 mm total), with 3 mm total being most common. Patients with less natural fat pad should have less expansion in the orthotic to maintain the padding under the heel bone, correspondingly, people with more natural fat pad may require increased heel cup expansion incorporated into the orthotic device.
“Orthosis Contour” refers to the prescriber’s preference to the shape of the orthotic frame compared to the foot model. 95% of the time "Symmetrical Orthoses with Lab Discretion” will be the best choice here. However, special cases do arise, especially when the left and right foot are distinctly different from one another, or only a single side foot impression is available and must be mirrored to complete the pair of orthotic devices. If you wish to have a different configuration for the left versus right foot, click the little chain link icon at the top middle of this field and you will be able to alter your prescription differently for each foot, such as in the case of amputation, congenital deformity, post trauma or surgery.
The next option is “Arch Height”. Several options are here, which allow you to raise or lower the medial arch of the orthotic from 0 to 6 mm incrementally from the arch height captured within the impression. So, if you are confronted with a flexible flatfoot, then lowering the medial arch somewhat may alleviate arch discomfort from the orthotic device,conversely if you are a proponent of the MASS theory, then raising the arch somewhat will encourage a somewhat supinated position of the foot during weight bearing. “Lower Proximal Medial Arch” is intended for those patients who experience pain or pressure in the transition area between the concave surface of the medial heel cup to the convex surface of the medial arch.
“Widen Entire Foot Model” is intended to allow for the splay type foot that expands transversely more than normal upon weight bearing versus non weight bearing.
Many of these concepts are incorporated into the various models of orthotic devices, and the default configuration for each model is designated within the app. Be mindful to change any of these defaults if needed, to truly customize your orthotic device prescription.
