Top 100 Biomechanical Guidelines #38: Evaluate Negative Casts for Inverted or Everted Forefoot Deformities

     The negative impression cast of the foot is the foundation of all Root-based Biomechanic/Orthotic treatment. It is an extremely important technique that the biomechanics industry is trying to replace with laser impressions, foam box impressions, and other variations of arch supports. Now that we are entering the age of CAD-CAM systems of manufacturing, it is up to the biomechanics industry to do the appropriate studies to decide when another technique will treat the problem as well as the classic Root Balance techniques based on the impression cast. For the appropriate patient, the power of the impression cast vs other techniques can be equivalent to treating a 1 inch short leg with a 1/4 inch heel lift. In the right direction, yes, helpful at resolving the abnormal forces producing symptoms, maybe not. From the patient standpoint, a significant dilemma exists. Are my symptoms not improving because I am in the wrong orthotic device, or because I need surgery, etc? For many years, the Root Device has been a tried and true method used by thousands of podiatrists/some physical therapists/some chiropractors/some orthopedists on millions of happy patients. When patients came into my office with orthotic devices 10 years ago, 90% of those orthotic devices were stable and reducing symptoms. Presently that number is diminishing. Patients need to expect more out of the orthotic devices if they do not feel stable, and they are not helping symptoms. Technology is a strong force to influence, but let us try.

     This Guideline #38 deals with understanding what they negative impression cast shows us. Below is the impression cast for a patient with forefoot valgus. This is the type of foot that the Root Balancing Technique shines and has no equal. If you have foot and ankle symptoms, and you have this type of foot, you should have a pair of these orthotic devices made.

The photo below is of a patient (Carina) with the forefoot valgus foot type where the first metatarsal is lower than the fifth metatarsal on observation. You can see if the cast captures this deformity by laying it on a flat surface. The cast will lean to the outside if the deformity is captured like the photo above.

Forefoot Varus is the opposite tilt seen where the first metatarsal is above the 5th metatarsal in this evaluation. The casts for a forefoot varus will lean inward like below.

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These casts only represent the relationship of the front of the foot to the back of the foot. They do not represent the foot to ground relationship ( a common misconception). I will have so much more on this concept. For biomechanics experts, I am intentionally not separating forefoot valgus from forefoot pronatus, plantar flexed first rays, and dorsiflexed lateral columns including dorsiflexed fifth metatarsals, for ease of this discussion.

In conclusion, I love when I find a forefoot valgus to support when I am dealing with many, if not most, foot and ankle problems. Forefoot valgus occurs in 40 to 60% of all patients. More on the more complex forefoot varus later.