3/5/2012 11:09 AM
I did a consult with a ProLab client yesterday regarding a patient who was laterally unstable and how best to write the orthotic prescription. He stated that in the biomechanical exam he measured the resting calcaneal stance position as nearly 10 degrees inverted. I then asked if he had performed the Coleman block test to determine whether it was the forefoot that was holding the foot inverted or if this patient had a rigid inverted rearfoot. He had not checked that and did not know the answer. This is a critical question when looking at a patient who has an inverted heel, so he decided to have the patient return to clinic so that he could perform the Coleman block test.
The Coleman block test consists of supporting the lateral forefoot in order to determine if an inverted heel is due to a forefoot issue, such as a plantarflexed first ray. A rigid plantarflexed first ray can result in inversion of the heel in order to bring the lateral forefoot to the ground. If the rearfoot is not otherwise rigidly inverted, and the lateral forefoot is supported, then the heel will evert to perpendicular.
In my office I often use a catalog or a pile of physical therapy prescription forms under the fourth and fifth metatarsal heads to support the lateral forefoot.
Our client did bring the patient back in and found that when he supported the lateral forefoot the heel came to perpendicular. In this situation, we prescribe an orthotic device that is aimed at supporting the lateral forefoot. We do not really need to worry about rearfoot control.
By definition, a properly balanced functional orthotic will balance the forefoot to rearfoot relationship. So, the orthotic plate itself will help support the lateral forefoot. In addition, I suggested adding a valgus forefoot extension to this orthosis. The extension will be started on the device (OD) and extend out under the metatarsal heads. A valgus extension is thicker laterally and thinner medially. We standardly start with the extension about 3 mm thick laterally, but this can be modified depending on how much is required under the forefoot to support it while doing the Coleman block test.
We also recommend gluing the cover of the orthosis posterior only, so it is easy to adjust the valgus extension by either increasing or decreasing its thickness. If the Coleman block test is negative, meaning that when the lateral foot was supported there was no change in the inverted heel position, then it would be contraindicated to add a valgus extension. In that case, the valgus extension would simply increase pressure under the metatarsal heads without changing the rearfoot position.
ProLab takes a scientific approach with our orthoses by integrating evidence-based medicine into orthotic therapy. Our team of Medical Consultants regularly evaluates the medical literature pertaining to orthotic therapy and biomechanics. ProLab clients are encouraged to contact a medical consultant whenever they have questions about an orthotic prescription.
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