The concept of peroneal muscle inhibition has both intrigued me and confused me, yet I do see it clinically and see the results, but the lack of objective data does trouble me. I started this discussion to get a better understanding of it. I am not sure it did.

The concept is that there is some sort of inhibition of the peroneal muscles, particularly the peroneus longus and the muscle does not work as it should. This “weakness” can lead to a range of symptoms from functional hallux limitus (and its compensations), increased risk for ankle sprains, lateral foot pain and maybe Achilles tendon pain. Muscle testing will show a significantly weaker peroneus longus. Its not clear what it is that leads to this inhibition which without objective data to consider that is a problem.

Typically with a mobilization of the proximal and distal tibiofibular joint, you can see an almost immediate return to the strength of the peroneus longus. I have certainly seen that plenty of times clinically and have no doubt about its clinical usefulness. However, I really struggle to come up with a coherent explanation of how the inhibition was  caused and how the mobilization overcomes it. It you have something to contribute, please head over to Podiatry Arena and contribute your ideas in the thread on this topic.

In my hands peroneal tendinopathy or tendonitis used to be a challenge. In the past I reckon I was close to a 100% failure rate in managing it. In the last 10 or so years I think I am now close to a 100% success in managing it. What changed? It was based on our research evidence. I talked about that in this blog post: Peroneal Tendonitis in Runners on my running research blog. It was pretty clear that almost everyone with peroneal tendinopathy had a lower than average supination resistance. That means the force needed to supinate the foot was low and as a consequence the peroneal tendons have to work harder, increasing the risk for tendinopathy. This also means that those with it need lateral wedging under the heel to decrease the loads in the tendon. That wedging actually leads to a substantial reduction in the forces that the tendon is subjected to, so hence the lateral wedging is a very and often is dramatically effective to manage peroneal tendonitis.

Yes, lateral wedges do try to pronate the foot more, but never had a problem with doing that. It did take a mindset change to get confident to start doing this 10 or more years ago, but I have not looked back. This is a perfect example of research informing and changing clinical practice.

This also means that a typically arch supporting medially wedged foot orthotic is going to increase the load on the peroneal tendon and is not going to be indicated. This also explains why I had almost a 100% failure on managing this in the past.

Also, of course, we do the usual load management approaches to this tendon once that reduction in load on the tendon with the wedge is done.

I am a big fan of teaching people how to measure the navicular drift and drop. However, the evidence is that for clinical use they are not that reliable, so that does limit the usefulness of these clinical tests in clinical practice.

Having said that, I still think we should be teaching how to do it, but in the context of the unreliability of them. The reason for this is that the concept behind navicular drift and drop does have implications for foot orthotic prescribing. What learning how to do the tests gives clinicians is an appreciation of the relative movements of the midfoot in the sagittal and transverse planes. Navicular drop measures the sagittal plane motion of the midfoot and navicular drift measures the transverse plane motion of the midfoot. Learning how to do the measurement of these two gives an appreciation of the relative motion of that midfoot in the sagittal and transverse plane. Once that appreciation and understanding is grasped, then there is probably no need to do the measurements on a routine basis in clinical practice. You can just observe it and note how much drop there is compared to how much drift there is. Are the about the same or is there more of one compared to the other?

My impression is that the amount of navicular drift should be about the same as navicular drop. If drop is greater, then that means that there is more movement in the sagittal place compared to the transverse plane. This means there is more arch collapse, when means that the foot orthotics need to have more support in the midfoot. If the drift is greater, then that means there is more movement in the transverse plane compared to the sagittal plane. This means that there is more movement of the midfoot medially rather than arch collapse. This means that foot orthotics need more medial and lateral support to control that midfoot transverse plane motion.

Functional hallux limitus is a theoretical construct. There is no doubt that the phenomenon that is functional hallux limitus exists, but that can often be as far any any agreement or consensus gets with this. There is no doubt that there are some feet when the foot is up in the air that there is a full range of motion available at the the first metatarsophalangeal joint yet when that foot is weightbearing during gait, that joint just does not want to move. That is the definition of what functional hallux limitus is.

I have written about this a lot, speculating that functional hallux limitus has many possible causes and that it may be better to conceptualize it as a nothing more that each person having a variable stiffness range of motion at the first metatarsophalangeal joint and that this may be related to the windlass mechanism. If this is the case then what we typically considered to be a functional hallux limitus is really the extreme of this variable stiffness and that functional hallux limitus probably exists as a continuum and not as an either/or entity.

The abductory twist is an observation that is frequently made during a gait analysis. Just recently I have started to notice a common terminology issue and I am somewhat confused if they are the same thing or separate things. Most people seem to use the term ‘abductory twist‘ as the same thing as a ‘medial heel whip‘. I believe they are probably different things and they get confused as to what the entity actually is.

I consider an abductory twist to be that sudden medial or abductory movement of the heel just as the heel come off the ground. I wrote here about the possible reasons for this, one being an ‘overpronation’ and the other being a functional hallux limitus. I do not consider that this comes from a more proximal problem like others do. Some people also call this a medial heel whip. They only way to help this is to deal with the ‘overpronation’ or functional hallux limitus. Exercises can not help this.

However, when you listen to or read about what some people consider to be a medial heel whip they are talking about the heel being whipped medially, especially in runners, after the foot has come off the ground. That is something different to the abductory twist that has been previously described. I do consider that this medial heel whip could be due to a proximal problem around the hip and pelvis. The only way to deal with this is deal with the proximal causes and exercises may be very helpful.

If you hear or read someone talking about an abductory twist and/or medial heel whip try to ascertain which one of the two entities they are talking or writing about and just when in the gait cycle that they are observed.