Toe biomechanics; too complicated to be understood or understudied?

[Gerrard Farrell]

Toe deformities, and in particular lesser toe deformities like hammer and claw toes, are extremely common in modern Western societies and can contribute to a whole range of debilitating conditions like metatarsalgia, Morton's neuroma and a much greater risk of falls especially in the elderly.

There is a lot going on in the forefoot during balance and gait but it surely not beyond the world of science to figure things out at least a little bit better than our present level of understanding.

Based on the personal observation of quite a lot of peoples feet, both pre and post intervention with an exercise device, I have come to the fairly strong conclusion that some of the smallest muscles in the body may be among the most influential in terms of gait and overall mechanics.

These muscles are the lumbricals and interossei of the foot and looking at them more closely has led me towards the idea of "functional lesser toe deformity", which is basically where the toes are in a normal alignment when not under high load but adopt hammer or claw toe configuration during manoeuvres such as Vele's forward lean.

I have found that "functional lesser toe deformity" can often be corrected with foot strengthening that targets the lumbricals and interossei.

I believe that function lesser toe deformity may lead to flexible toe deformity and on to fixed toe deformity that may require surgery.

feet-70573_1280 (2).jpg

[Gerrard Farrell]

Can "functional lesser toe deformity" contribute to the risk of plantar plate tears?

Well, flexible lesser toe deformities, like hammer and claw toes, are thought to contribute to the risk of tears and these deformities can be caused by weak intrinsic foot musculature. Plantar plate tears are common in runners and athletes, especially athletes involved in sports involving impact or high speed cutting manoeuvres. Forefoot injuries like plantar plate tears or damage to the transverse ligament can mean months out of the game.

If flexible toe deformities can increase the risk of plantar plate tears during activities like sports, then it seems logical to me to conclude that "functional lesser toe deformities" will increase the risk by the same mechanisms. Remember that I am postulating that the hammer toe configuration show in the image in the previous post constitutes a functional deformity that will impact mechanics.

It is important to remember that the majority of the intrinsic muscles of the foot insert onto the bases of the proximal phalanxes of the lesser toes. These muscles seem to be largely ignored by some clinicians ,which is extraordinary give their importance to foot mechanics.

If functional lesser toe deformities increase the risk of plantar plate tears, wouldn't it be wise to reverse these deformities, where present, by strengthening the lumbricals and interossei ?

Clarification ;

1 Toes which are held more or less straight during quite standing but which buckle under the load produced by Vele's forward lean >"functional lesser toe deformity"

2 Toes held in a hammer toe/claw toe configuration during quite standing and when not heavily loaded but which can be manually straightened > flexible toe deformity

So functional toe deformity and flexible toe deformity are separate but very closely related beasts which might carry comparable injury risk for athletes.

I have included a link to a youtube video of my foot under load during a single leg raise . As my heel lifts the toes remain straight. My foot is strengthened . I have found others with strong feet who's toes remain straight under load include judo layers and a few avid hillwalkers.

https://youtu.be/TssDyMtb0sA?si=qWOUYAX8Ek2X3rI-

[Gerrard Farrell]

Some might say, "if lesser toe deformity can be reversed or prevented by strengthening exercises, then where is the evidence?"

That would be a fair question. In my view, which I believe is supported by the evidence, you need to strengthen the lumbricals ,interossei and FDB if you want to prevent functional lesser toe deformity or prevent it getting worse. Toe curling exercises will get you nowhere since these involve turning the lumbricals and interossei "off" to allow flexion of the IP joints (these muscles straighten the IP joints) .

Functional foot strengthening exercises like hopping or calf raises may also fail if loading the toes during such exercises causes a collapse of the toes into a hammer toe configuration from the start . The very muscles you are trying to target are not in use during the exercises if the toes display functional lesser toe deformity. You might even be strengthening the flexor digitorum longus which might cause weakening of the lesser toe intrinsics.

Previous research has shown extrinsic foot muscle strengthening done before intrinsic strengthening can cause significant intrinsic foot muscle weakening.
Ketachi et al Differential effects of intrinsic- versus extrinsic-first corrective exercise programs on morphometric outcomes and navicular drop in pediatric flatfoot

If you come across a subject who's toes collapse under load, I believe it may be wise to address this at once, or certainly before embarking on functional exercises based around collapsing toes. A foot may need to function properly before it can be strengthened uniformly.

If anyone is working on research concerning functional exercises and the intrinsic foot muscles, they could do worse than take cognisance of this thread.

Get the foot working properly, with toes staying straight and flexing around the MTPJs ,then strengthen the whole.