Current Insights On Custom And Prefabricated Foot Orthoses

Author(s): 
Guest Clinical Editor: Scott Spencer, DPM

“Unfortunately, I have seen patients go to ‘national chain foot stores’ that are owned by either an orthotist or pedorthotist, stand on a pedigraph and come out with a supposed ‘custom’ made device,” recalls Dr. Kimmel. “These devices are expensive and sometimes hinder our ability to make a custom-made device because of patient misconceptions.”

Q: Is there an area of the foot that you feel requires more influence from a foot orthotic device than perhaps other areas?
A:
Dr. Volpe notes the importance of all components of a custom foot orthosis. That said, he notes that in motion-controlling devices, critical components are the conformity of the shell to the heel, arch and midfoot. The heel cup, especially with added intrinsic plaster modifications, is a key component that aids the device’s ability to control or modify subtalar joint function, according to Dr. Volpe. He says these features will contribute to a shell that will produce a more medial orthotic reaction force (ORF) to the subtalar joint axis, which leads to a net supinatory effect. Furthermore, he says an extrinsic rearfoot post can be an important addition to the device. Dr. Volpe adds that this can help stabilize the device in the shoe and help decelerate pronation after heel contact when necessary.

As Dr. Volpe says, the stage for midfoot and forefoot pathology, including metatarsophalangeal (MPJ) deformities, is often set by rearfoot dysfunction. He notes one of the keys to improving the function of the distal segments of the foot is adequate influence on the proximal segment.

Dr. Kimmel feels if one does not control the motion in the rearfoot (subtalar) joint, the device is nothing more than an accommodative device as opposed to a functional device. He explains that controlling any excess motion in the rearfoot will influence the midfoot and the rest of the foot. He likes to have his patients wear a device that is extrinsically posted in the rearfoot with a little deeper heel cup.

Unfortunately, Dr. Kimmel says most patients cannot get these orthotics in traditional dress shoes like loafers or wingtips. Although intrinsically posted orthotics are easier to fit in most shoes and have a better compliance, Dr. Kimmel notes a loss of functionality.

Dr. Spencer does not believe that he must focus on one specific area to create a foot orthotic that will properly serve the patient. He stresses the importance of getting a clear idea of what all the areas of the foot are doing during function, and addressing those areas with the orthosis.

Dr. Spencer also emphasizes having a strong understanding of the implications that the rearfoot, midtarsal joint, lesser tarsus, lesser metatarsals, the first ray and the lesser digits will have on overall foot function. After getting an idea of what these areas are capable of and seeing what they are actually doing during gait, he says one can successfully prescribe a foot orthotic to address these areas.

Q: How do you see foot orthotic therapy evolving in the next five to 10 years?
A:
Dr. Kimmel recalls starting his practice at the tail end of the Rohadur era and the beginning of the graphite era. He thinks new materials are going to come out that allow clinicians easy adjustment of devices in the office and still provide some of the benefits of Rohadur. Polydur, a material that is similar to Rohadur, does not have the same number of benefits, according to Dr. Kimmel. Dr. Kimmel also feels new computerized casting techniques might allow a practitioner to cast and make an orthotic in the office in a short period of time.

Dr. Spencer sees more use of pressure measurement systems in the prescribing and adjusting of orthotic devices. He employs the F-Scan system (F-Scan) to assess plantar foot pressure and the timing of pressure distribution, and equalizing this pressure pattern and timing between both feet. As Dr. Spencer points out, this is one area that DPMs cannot analyze via measurements or watching the patient walk.

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