Forefoot Equinus aka Psuedoequinus, Anterior Cavus, Plantarflexed Forefoot

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I have my thoughts on this, would love to hear others experience/articles on the prevalence, treatment, lack of literature. The only thing I've found written is by Howard Dananberg on the Vasyli website "Thinking Straight."

Please share your experience and/or literature you are aware of.

Thanks,
Ted

 

A thread from back in 2009 where we discussed it:

http://www.podiatry-arena.com/podiatry-forum/showthread.php?t=32635

 

It is discussed in this old (and very outdated) paper also:

http://m.ptjournal.apta.org/content/68/12/1840.short

 

Thanks Griff, I did a search but didn't find that discussion.

Keep em comin!

 

wow nearly 6 years ago and many a post later

Time flys

 

I'll stir the pot a little.:hammer:In my clinical experience, I find this foot structure very common, especially in women. I have had many patients improve simply by putting them in a wedge shoe that has around 3/4" heel to ball drop. Before someone jumps the gun, I check every one of my patients for ankle equinus. Many times all previous treatments had failed to relieve their symptoms.

 

Don Green wrote about this in the late 70's early 80's. It does make perfect sense. If you have two feet that are equal in the rearfoot and one has its forefoot more plantar flexed on the rearfoot you will see this condition. The forefoot can't plantar flex into the ground, so the "compensation" is to dorsiflex the ankle.

I don't know if I would call this common. My off the cuff sense is that it is less than 1 in 10.

I agree, that a heel lift of some kind will often help this foot.

An ankle equinus does not necessarily cause STJ pronation.

Eric

 

Alan Whitney and Don Green coined the term "pseudoequinus" (as far as I know) and coauthored the first paper on the subject (Whitney AK, Green DR: Pseudoequinus. J Am Podiatry Assoc 1982; 72:365-371). I remember reading when it first came out during my 3rd year of podiatry school.

Even though I greatly respect Don Green (who is also a great personal friend of mine) and Alan Whitney, I have some real problems with the term "pseudoequinus".

For instance, please tell me when does a foot with an "equinus deformity" become a foot with a "psudoequinus deformity"? In other words, at what level of forefoot plantarflexion to the rearfoot does an equinus deformity stop becoming an "equinus deformity" and start becoming a "pseudoequinus deformity"?

Also, when we have an flatfoot deformity that has 10 degrees of "ankle joint dorsiflexion" when the subtalar joint (STJ) is pronated, which is the STJ rotational position that this foot is most comfortable functioning in, and we then supinate that foot into the STJ neutral position and find that this foot now has only 2 degrees of "ankle joint dorsiflexion", have we created a "pseudoequinus deformity" by putting that flatfoot into an unnatural functioning position for it?

It has been a very long time that anything of academic substance like this has come up on Podiatry Arena for us to chew upon...looks like "Newsbot" is the only one that has been posting recently....and Podiatry Arena used to be such a fun place to visit.....not so recently............

 

I should refine my statement about common. How about common in symptomatic feet.
Eric, thinking this way does it change your thoughts on prevalence?
Kevin- I do have a question for you, but it has to wait as it's late. I will respond tomorrow.

 

Similar is idea I guess is there a Supinatus Forefoot or Valgus Forefoot, The Valgus forefoot will generally appear to have a Plantarflexed Forefoot on the Rearfoot

I don?t like the pseudoequinus term either, Forefoot Equinus makes sense and then degrees of stiffness might be a way of describing it ?

 

Doesn't look like anyone who supports using the term "pseudoequinus" wanted to answer my questions.

Here are the problems with the term "pseudoequinus".

When podiatrists measure "ankle joint dorsiflexion", they are not, in fact, measuring only motion at the tibio-talar joint (i.e. ankle joint). Since the distal reference segment for the measurement of "ankle joint dorsiflexion" is the forefoot, then "ankle joint dorsiflexion" is not only a measure of tibio-talar joint dorsiflexion, but also of subtalar joint dorsiflexion, midtarsal joint dorsiflexion, midfoot joint dorsiflexion and even plantar forefoot soft tissue compression.

With that fact in mind, we, as podiatrists, by definition, have chosen to use the plantar forefoot relative to the tibia to be our measure of "ankle joint dorsiflexion" when, in fact, we are measuring the motions of at least three other joints other than the "ankle joint" when we measure "ankle joint dorsiflexion" on our patients. Therefore, as long as we choose to say that an "equinus deformity" is when there is less than 10 degrees of dorsiflexion of the plantar forefoot relative to the tibia, then there should be no "pseudoequinus" deformity since the forefoot is always the distal reference segment used to measure "ankle joint dorsiflexion".

In other words, "pseudoequinus" is still an "equinus deformity", no matter what we think, as long as we persist to use the forefoot as our distal reference segment when we measure "ankle joint dorsiflexion" since we are not truly measuring only tibio-talar motion (i.e. only ankle joint motion) when we measure "ankle joint dorsiflexion".

The dorsiflexion stiffness of the subtalar, midtarsal and midfoot joints are highly variable from one individual to another so that in one individual a certain magnitude of plantar forefoot force may cause a large degree of motion at these joints whereas in another individual the same magnitude of plantar forefoot force may cause a relatively small range of motion at these joints. We simply don't know how much motion is occurring at these joints since we don't measure these motions when we perform any of the "ankle joint dorsiflexion" tests such as the "lunge test" or the manual non-weightbearing tests with the knee extended or flexed as advocated by Root et al.

For this reason, it is probably best we call the tests that we currently use to measure "ankle joint dorsiflexion" by the more accurate term of foot dorsiflexion, since our current measurements are probably as much a measure of motions at the pedal joints as a measure of motion at the ankle joint.

 

Although when you do see a plantar flexed forefoot on the rearfoot, you should certainly think about anterior ankle impingement and forefoot problems related to an early heel off. The terminology is not very good, but if the research were done, I would bet there would be some correlation with some pathology.

Eric

 

Sorry duplicate

 

I too prefer forefoot equinus. Just seems to be a more accurate terminology of the structure we are discussing. "Plantar flexed forefoot on the rearfoot" is probably the most accurate terminology, but it is kind of wordy.

While I agree with Kevin about "foot dorsiflexion" and the potential effect of multiple joints, when I examine for this condition I do my best isolate the other joints out by fully dorsiflexing the hallux and attempting to keep the subtalar joint in neutral.

This is done with the knee fully extended and then flexed. If they have know ankle dorsi with the knee extended and feel tension in the calf, I refer them to PT/Stretching. If they don't feel tension, the knee is the flexed and if the dorsi doesn't increase and they still don't feel tension they are refereed out for ankle joint mobilization and or xray's.

While this process is going on I look for "plantar flexed forefoot on the rearfoot" when(if) the ankle joint hits 90*, if it's there they get treated for it.

Is my technique perfect? I think it's pretty good, but you may get different impressions than I. Is it useful, I believe very, and have had good clinical success with my evaluations.

I'm looking for a discussion on this as it's seemed to help many of my patient's and seems very under underutilized/documented.

 

Kevin wrote-
"Also, when we have an flatfoot deformity that has 10 degrees of "ankle joint dorsiflexion" when the subtalar joint (STJ) is pronated, which is the STJ rotational position that this foot is most comfortable functioning in, and we then supinate that foot into the STJ neutral position and find that this foot now has only 2 degrees of "ankle joint dorsiflexion", have we created a "pseudoequinus deformity" by putting that flatfoot into an unnatural functioning position for it?"

Kevin- I've seen this condition in some of my patients, but have not seen any literature on it. Can you please explain the biomechanics of this structure?
Also your thoughts on treating it if it is symptomatic?

Thanks,
Ted

 

When you dorsiflex the ankle to resistance, you can pronate and supinate the STJ without moving the talus in the ankle mortise. With STJ supination there will be a relative plantarflexion of the lateral column of the foot relative to the leg. This may be more of an effect of the inversion motion lowering the lateral aspect of the foot. This concept was probably discussed in Root Orien and Weed, but it was so deeply embedded in my learning, I can't tell you where they wrote it. My best guess would be normal and abnormal function of the foot volume 1. Kevin's point was: this measured change in "ankle dorsiflexion" occurs without any ankle motion. Is this really an equinus or a technique error? Or is it a logic error in assuming that STJ should function in neutral position?

If you see something that is symptomatic, by all means treat it. However, lack of ankle joint range of motion, may not be what is causing the symptoms. You should always try to explain why your exam findings are relevant to the pathology. I do this with mechanical modelling of what I think the injured anatomical structure is. Kevin and I wrote a chapter on this concept.

Eric

 

Ted:

I don't treat "foot deformities". Rather, I treat specific pathologies and injuries.

Therefore, unless you can be more specific as to what the exact injury is and how having a foot with an equinus with an increased forefoot plantarflexion angle relative to the rearfoot is the cause of this injury, I don't see how I am going to be able to help you.

Maybe, first ask yourself, Ted, how is a foot that has a forefoot that is more plantarflexed on the rearfoot with an equinus deformity any different than a foot that has a forefoot that is less plantarflexed on the rearfoot that also has an equinus deformity.