Ever wondered which is the best method for casting orthotics?
This is a question that plagues many. Weight bearing casts done in foam boxes has always made us wonder; how on earth can you get a corrective cast if you are actually taking a pathologic imprint of the foot? Don’t you want it to be cast in a position of subtalar neutral so that the foot is corrected in its position when weight bearing? Many know little about the scientific basis for casting methods. If you have some good articles, please send them to us.
From the Foot And Ankle Center of Washington, USA:
“The most important criteria is the experience and skill of the medical practitioner, but regardless, there are some techniques that have been shown to be much more effective than others. The only method that has been shown in the medical literature to be effective in producing a quality functional custom foot orthotics is a three-dimensional non-weightbearing cast or image of the foot. In this technique the foot is held in a precise position – essentially the position in which it should function. The image of the foot can be taken using plaster, fiberglass, or a laser scan….
Are There Other Methods to Take a Cast of the Foot for Orthotics?
There are 3 other methods used for making custom orthotics, but they have been shown to be ineffective for making orthotics that improve function of the foot (although they can be used to make simple arch supports). The three techniques are:
- Plaster or foam box casting where the patient sits and the foot is placed down on the floor to produce the cast.
- Walking across a force plate
- Standing on a digital imager of the foot.
Several studies have shown all of these methods to be less effective at producing well-functioning orthotics.
A 1989 Northern Arizona University study showed that having any weight on the foot during the casting or imaging process resulted in an orthotic shape that has been shown to cause pain in the big toe joint and tension on the plantar fascia.1, 2
A 2002 study from the Joiner Center for Sports Medicine at the University of Delaware showed that weight-bearing casting resulted in abnormal force under the big toe joint.3 This has been shown to result in the production of an orthotic that does not work well at reducing the forces that lead to common foot problems such as bunions, big toe joint pain, heel pain, arch pain, plantar fasciitis and other conditions.1 Non-weightbearing casting was recommended as the most reliable and valid method for making custom foot orthotics.3 .
Summary of Information about Casting for Custom Foot Orthotics
- Only a non-weightbearing cast should be used (see figure 1)
- Weight-bearing casts and images of the foot have been shown in the medical literature to be ineffective methods for producing functional foot orthotics.
- Whether you are sitting or standing does not matter. If your foot is on the floor during the casting process, you are not likely to get an orthotic that provides optimum function.
The medical literature indicates that walking across a pressure mat cannot provide enough information to make a quality functional orthotic.
- The doctor, and not an assistant, should take the cast of your foot.References
1 Forefoot to Rearfoot Angle – A Comparison of Orthotic Casting Techniques. McPoil, TG; Schmit, D. Phys Ther. 1989 Jun;69(6):448-52
2 Position of the First ray and Motion of the First MTP. Roukis, et. al 1996 JAPMA. Vol. 86:11
3 A comparison of four methods of obtaining a negative impression of the foot. McClay-Davis I, Laughton C, Williams, DS. J Am Podiatr Med Assoc. 2002 May;92(5):261-8
Custom-made foot orthoses for the treatment of foot pain:http://www.ncbi.nlm.nih.gov/pubmed/18646168
Evolution of foot orthotics–part 2: research reshapes long-standing theory:http://www.ncbi.nlm.nih.gov/pubmed/11896382
Listed on the Foot and Ankle Center of Washington: http://www.footankle.com/Orthotic-Research.htm