Spanking the orthotic: The effects of hallux limitus on the foot’s longitudinal arch.

But the issues do not stop at the arch. If you have been with us long enough, you will have read about the effects of the anterior compartment (namely the tibialis anterior, extensor digitorum and hallucis and peroneus tertius muscles) strength and endurance on the arch.

Here we have a very troubled foot. This foot has undergone numerous procedures, sadly. Today we will not talk about the hallux varus you see here, a virtual unicorn in practice  (and acquired in this case) nor do we want to discuss the phalangeal varus drift. We want to draw your attention to the obvious impairment of the 1st MTP (metatarsophalangeal joint) dorsiflexion range.  You can see the large dorsal crown of osteophytes, a dorsal buttress to any hallux dorsiflexion.  There is under 10 degrees of dorsiflexion here, not even enough worth mentioning.  We have said it many times before, if you lose a range at one joint usually that range has to be accommodated for proximal or distal to the impaired joint. This is a compensation pattern and you can see it here in the hallux joints themselves.

Here you can see that some of the dorsiflexion range has been acquired in the proximal phalangeal joint.  We like to call this “banana toe” when explaining it to patients, it is a highly technical term but you are welcome to borrow it. This occurred because the joint was constantly seeing the limitation of dorsiflexion of the 1st MTP joint and seeing, and accommodating to, the demands of the need for more dorsiflexion at toe off. 

But, here is the kicker. You have likely seen this video of ours on Youtube on how to acquire a foot tripod from using the toe extensors to raise the arch.  Video link here  and here.  Well, in his patient’s case today, they have a limitation of 1st MTP dorsiflexion, so the ability to maximally raise the arch is impaired. The Windlass mechanism is broken; “winding” of the plantar fascia around the !st MTP mechanism is not sufficiently present. Any limitations in toe extension (ie dorsiflexion) or ankle dorsiflexion will mean that :

1. compensations will need to occur

2. The Windlass mechanism is insufficient

3. gait is impaired at distal swing phase and toe off phases

4. the anterior compartment competence will drop (Skill, endurance, strength) and thus injury can be more easily brought to the table.

In this patient’s case, they came in complaining of burning at the top of the foot and stiffness in the anterior ankle mortise area.  This would only come on after a long brisk walk.  If the walk was brisk yet short, no problems. If the walk was long and slow, no problems.  They clearly had an endurance problem and an endurance challenge in the office showed an immediate failure in under 30 seconds (we will try to shoot a quick video so show our little assessment so be patient with us). The point here today is that if there is a joint limitation, there will be a limitation in skill, strength or endurance and very likely a combination of the 3. If you cannot get to a range, then any skill, endurance or strength beyond that limitation will be lost and require a compensation pattern to occur.  This patient’s arch cannot be restored via the methods we describe here on our blog and it cannot be restored by an orthotic. The orthotic will likely further change, likely in a negative manner, the already limited function of the 1st MPJ. In other words, if you raise the arch, you will shorten the plantar fascia and draw the 1st MET  head towards the heel (part of the function of the Windlass mechanism) and by doing this you will plantarflex the big toe … .  but weren’t we praying for an increase in dorsiflexion of the limitus big toe ? ……..yes, exactly !  So use your head  (and spank the orthotic when you see it used in this manner.  ”Bad orthotic, bad orthotic !”)

So think of all of this the next time you see a turf toe / hallux rigidus/ hallux limitus. Rattles your brain huh !?

This is not stuff for the feint of heart. You gotta know your biomechanics.

Shawn and Ivo … .the gait guys

Addendum for clarity:

a Facebook reader asked a question:

From your post: “if you raise the arch, you will shorten the plantar fascia and draw the 1st MET head towards the heel (part of the function of the Windlass mechanism) and by doing this you will plantarflex the big toe … . but weren’t we praying for an increase in dorsiflexion of the limitus big toe ? ” I always thought when the plantar fascia is shortened, it plantar flexes the 1st metatarsal (1st ray) and extends (dorsiflexes) the 1st MTP joint….

Our response:  

We should have been more clear, our apologies dear reader.  Here is what we should have said , ” The plantar fascia is non-contractile, so it does not shorten. We meant conceptually shorten. When in late stance phase, particularly at toe off when the heel has raised and forefoot loading is occurring, the Windlass mechanism around the 1st MET head (as the hallux is dorsiflexing) is drawing the foot into supination and thus the heel towards the forefoot (ie passive arch lift). This action is driving the 1st MET into plantarflexion in the NORMAL foot.  This will NORMALLy help with increasing hallux dorsiflexion. In this case above, there is a rigid 1st MTP  joint.  So this mechanism cannot occur at all. In this case the plantar fascia will over time retract to the only length it does experience. So, if an orthotic is used, it will press up into the fascia and also plantarflex the 1st MET, which will carry the rigid toe into plantar flexion with it, IN THIS CASE.”

Hallux Varus: The anti-bunion. Thinking of bunion surgery ? This could be a complication if things go sour.

Hallux varus, when the big toe drifts medially, is a real problem. It is typically an acquired problem from a hallux valgus/bunion surgery gone awry.  (This post will not delve into some of the suspected culprits of this problem including Mc Bride, Scarf, Chevron or Akin osteotomy etc but that would be some of the reader’s next steps into diving deeper into this problem. Surgical procedures to the 1st ray was one of the gait guys senior orthopedic residency thesis topics, hence we now hate this topic !). 

This deformity can be rigid or flexible.  This case seen in the photo walked into our office recently.  These are not all that common and you won’t see many of them, but you do need to know they exist and where they can come from, how to cope with them and what issues you will need to understand (ie. footwear, talked about below) to assist your client. 

Hallux varus can be painful, uncomfortable and even debilitating in some cases.  Sometimes they necessitate fixation to realign the hallux bone along a more reasonable alignment with the shaft of the 1st metatarsal. 

 

Early correction seems critical because the linear and rotational forces at work generating the deformity can eventually lead to a further progressing deformity that can be even more problematic. When left unaddressed more drastic and radical corrective interventions seem necessary, including but not limited to, resection of the base of the proximal phalanx, fusions and tendon transfers. However, newer surgical procedures are coming along proposing things like reconstruction of the lateral stabilising components of the first metatarsophalangeal (MTP) joint. 

 

So here at The Gait Guys we like to ask the big, and sometimes obvious, questions.  What is toe off in walking and running gait going to look like in this hallux varus case ?  Well, one has to consider that the normal linear and rotational forces are now changed.  This means that the normal eccentric axis of the 1st MPT joint involved is going to very likely be changed. This means that the clearance of the base of the phalanx could be impaired and lead to painful binding, grinding or locking of the toe prior to reaching the adequate range of dorsiflexion for normal toe off. Additionally, the toe may act functionally unstable as the rotational forces remain unchecked leading to joint instability. Naturally, the medial foot tripod will be impaired and since the big toe acts in part like a kickstand to help support and fixate the 1st metatarsal (medial tripod), pronation forces can remain unchecked and beyond normal.  Naturally the foot will attempt to shift the tripod stability elsewhere and often this goes to the 2nd metatarsal commonly found with hammering of the digit in an attempt to help with stability through increased long flexor tone (FDL). Pain with a hallux varus can be a bigger complaint than the unsightly surgical outcome.

 

There is so much more to this topic. We could go on for at least another 50 pages on this topic (as our thesis reminds us) but volume is not the point of today’s task. It was to bring something new to light for our brethren here at The Gait Guys.  In the photo above, you see drift of the lesser toes, seemingly to follow the big toe. What you need to know is that this is not typical, however not impossible one could propose. This client had some other forefoot procedures done that were largely, although not exclusively, related to that lesser digit drift. Regardless, this is a client that is in some amount of foot trouble. They had good mobility of the 1st MTP joint, so full toe off was possible but because of the instability and uncontrollable rotational forces the joint was painful. A simple intervention made her life infinitely more comfortable, moving her into rigid rocker bottomed shoes.  Dansko clogs for work, and ROCS shoes for walking.  This left us with a very happy client. Not bad, all things considered.  In the mean time we will watch for deformity progression even though the patient could not be urged to have another surgery probably even if their life depended upon it. 

 

In summary, being a patient can be difficult. These days, more than ever it seems, one needs to do their homework and be their own advocate.  Prior to surgery several consults should have taken place, risk and rewards should have been discussed, realistic outcomes dialogued and perhaps most of all questioning whether surgery needed to be on the table in the first place. Remember, surgery is most wisely selected in cases of neurologic decline and excessively painful and further detrimental biomechanics (ie. unaddressed ACL deficiency eventually promoting secondary instability with time). If there are ways around either, they should be explored. Cosmetic correction should never be on the table, and in the case of the foot, nor should poor shoe choices that promote problems.