As you know many patients have inverted forefoot deformities. This is the relationship between the forefoot and rearfoot in neutral subtalar joint positioning. Typically measured with the patient prone, you then place the subtalar joint in its neutral position, and measure the angulation of the first through 5th metatarsal heads to the plantar surface of the heel (or perpendicular to the heel bisection line if drawn). If the first metatarsal is elevated to the fifth, you have an inverted forefoot deformity of some kind. These deformities can be fixed, related to soft tissue contractures, or a combination of these two factors. The fixed inverted deformities are called forefoot varus or plantar flexed 5th rays. Both will produce contact phase pronation where the foot has to overly pronate for forefoot loading to get the first metatarsal on to the ground. Both plantarflexed 4th rays or metatarsus primus elevatus can produce this pronatory force with or without a forefoot varus angulation. The balancing of these deformities with the use of custom made the Root Balanced functional foot orthotic devices revolutionize the orthotic world over 60 years ago thanks to Dr Merton Root and still very practical today. So, you can measure forefoot angulations in subtalar joint neutral and decide how to balance them out.
The inverted forefoot deformities that can change with custom inserts that mimic forefoot varus are forefoot supintus and a dorsiflexed first metatarsal due to functional jamming dorsally. Any patient with inverted forefoot deformities, that are given orthotic devices to achieve forefoot balancing, should be re-evaluated about a year out. If there is more than a 2 degree difference, the difference associated just to measurement inconsistencies, a new impression and orthosis can/should? be made at that time. The classic example is an inverted forefoot with an everted heel in Resting Position. The heel eversion is the driving force to artificially induce an inverted forefoot by soft tissue contractures and joint dysfunctions. I never was able to distinguish them from a forefoot varus initially. I have to wait for them to change. Dr Root said that as the change happened in his Rohadur devices, the patients may break their orthoses since their foot no longer matched. I never witnessed last, but have mainly used polypropylene for the last 39 years! We call this changeable forefoot varus a forefoot supinatus. The same would occur in a dorsiflexed first metatarsal being jammed up by pronatory forces.
This post is meant for concepts and terminology review. The concept of a changeable forefoot to rearfoot relationship also occurs on the everted forefoot deformity side of the equation. I am basically saying that if we can lower ground reactive forces medially, we have a chance to reduce nonfixed deformities like forefoot supinatus or dorsiflexed first rays. Both these deformities increase the pronatory stresses or moments in our feet, both these deformities limit the quality of life of these patients from functional disabilities, so their reduction can only be a good thing for us.
I hope you can see I love foot strengthening exercises as part of my biomechanical approach to patients. What are the 3 most important exercises? The 3 most important foot exercises are: posterior tibial, peroneus longus, and intrinsic muscles. Almost all your patients should be doing these 3-4 times a week. I bring this up now due to the peroneus longus effect on the first ray. And we can also add the flexor hallucis longus as 2nd commander to a powerful push off. Simple to at least encourage Strengthening 101 Active Range of Motion exercises for these 2 tendons.
What will strengthening of the peroneus longus do for you? The peroneus longus has 3 normal functions of lateral foot and ankle stabilization, arch support, and first ray plantarflexion. Strengthening the peroneus longus will develop a more plantarflexed first ray. I am amazed at young athletes and their ability to reduce the forefoot supinatus flat foot nature of their foot into a normal to high arch more normal forefoot to rearfoot relationship. Of course this has to happen when they are young, definitely by 20 their feet are getting more rigid and less moldable.
So, in these inverted forefoot deformities with flat feet, you control the medial column as best as you can, strengthen the peroneus longus and FHL, get them as active as possible, and measure changes to deformity and strength and quality of life on a yearly basis. These patients will be improved incredibly. You have added wonderfully to their life. Job well done!!
