Dear All,
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I have a question to ask that (I'm sure) there is a very simple answer to. As ever, my embarassment at asking such a simple question is only countered by my certainty that I will come out of it being wiser.
Hypothetical patient (I saw a few patients over the course of a week or so with very similar presentations and don't want to present them all)who has pain in the metatarsophalangeal joints(MPJs) from 2-4. There is marked callus on the aforementioned MPJs. Static sub talar joint(STJ) axis is medially deviated. Weight bearing there is greatly increased 1st MPJ dorsiflexion stiffness and normal (possibly slightly high)supination resistance. Low arch position with more navicular drop than drift.
I'm not one for looking at FF to RF relationship much but the relationship was "neutral" other than the 1st MPJ being superiorly positioned relative to the 2-4 MPJs and the 5th MPJ being similarly so. i.e. dorsiflexed 1st and 5th MPJs. Possibly slightly short 1st metatarsal shafts?
2D shows late heel rise and considerable navicular drop/mid tarsal joint"break" at late stance. There is lack of Winlass function and abductory twist presumably to overcome the 1st MPJ stiffness.
I was somewhat torn in treating these cases. There was no obvious cause of the metatarsal pain other than transfer of pressure from the 1st MPJ laterally as the medial column became more dorsiflexed and the foot pronated more. Obviously the abductory twist increases the shear force.
Here is my question - if you have waded through the waffle to get to this point:
My goal is to reduce the forces on the metatarsals - compression and shear. Should I be trying to encourage more plantarflexion of the 1st ray in mid to terminal stance? If I laterally post the forefoot, I can shift the centre of pressure(COP) laterally and encourage that plantarflexion. THis will partially redistribute the load across the forefoot and should reduce 1st MPJ dorsiflexion stiffness.
i.e. reduce compression and shear.
However, in order to do so, do I not risk actually increasing the pressure on the 2-4 MPJs with the lateral posting? Obviously a device wedged at the rear foot with a medial longitudinal arch support will reduce some of the pronation moments that are forcing the medial column into dorsiflexion.
The easiest thing would be to create a device that has FF extension(or a full length EVA device) with a 2-4 MPJ cut out and a mortons extension. This will reduce the compression on the 2-4 MPJs. However, I am never comfortable increasing the dorsiflexion stiffness at the 1st MPJ and this device will almost certainly have that effect.
Does anyone have any thoughts? Does anyone else see people that present in a simlar way or am I unique?
Thanks for reading my ramblings
Robin
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Put your head in the furnace Robin and ask the great questions only you feel are silly, I do it all the time :eek:
Assuming your hypothetical patient has non-painful ROM of 30 degrees or more dorsiflexion at the 1st MPJ I would consider a 2-5 bar and first ray cutout or possibly casting the 1st more plantarflexed and adding a medial skive. I think it really depends on the patient, their activity, your goals and especially the STJ axis, midtarsal joint compliance and any potential forefoot compensation to begin.
Rigid deformities of the first I would agree with your suggestion of a Morton's extension but I would try to use a stiffer device than EVA IF possible.
Regards. -
They all had sufficient 1st MPJ ROM
Yes, it is almost certainly FnHL but my goal is to offload the mets 2-4. 2-5 bar post will increase the force under the 2-4 mets, albeit that it will probably create a more evenly distributed load across the whole forefoot.
I'm suppose what I am trying to ask is which is the lesser of the 2 evils. In fairness, I think I am doing a poor job of getting my question across
Robin -
Hi Robin,
some reading of course
The influence of metatarsal support height and longitudinal axis position on plantar foot loading
If you are trying to reduce the plantar loading on the 2nd and 3rd mets and reduce dorsiflexion stiffness at the same time - I think that what your asking.
Device to reduce the pronation moments, deal with the midtarsal joint , with a metatarsal pad behind the 2nd -3rd met heads , it will reduce the plantar loading at the 2nd and 3rd MTPJs- which should reduce the shear and compression forces at the met heads and as an added bonus at the same time increasing the GRF distailly to the 1st MTPJ, which all things being equal help dorsiflex the 1st MTPJ or at least help over come the increased dorsiflxion stiffness. You could also add a Cluffy wedge as well which would preload the Hallux in a dorsiflexed position.
so device may look like
medial skive
higher arch
metatarsal pad behind 2nd and 3rd MTPJs
cluffy wedge
Hope that helpsand what you were asking. -
In one sentence, you have concisely put what took me a virtual essay to get across - many thanks
It does - it was what I was expecting.
Only issue with it was that, looking at the tissue steress model, there are other ways of giving the same offload to the mets(if pressure was the factor to be treated). Unfortunately, my fear of using any other method would be the long term consequences at the 1st MPJ
Cheers
Robin
PS Does anyone else see this regularly? -
Hi Robin,
When you place the subtalar joint in its neutral position (joint congruity, by my definition), what is the position of the 1st metatarsal and hallux relative to the second metatarsal? Is the first metatarsal elevated relative to the lesser metatarsals? If so, you may be dealing with a Primus Metatarsus Supinatus Foot structure.
You can read more about this foot structure on my research site: www. RothbartsFoot.es
with regards,
Professor Rothbart -
Also, there is more than one way to decrease dorsiflex stiffness of the 1st MPJ with an orthosis. A medial heel skive will decrease pronation moment from the ground so that the windlass can supinate the foot easier.
Eric -
Greisberg, J., Prince, D. & Sperber, L. (2010) ‘First ray Mobility Increase in Patients with Metatarsalgia’ Foot & Ankle International Vol. 31, No. 11: 954 - 958
thought you might like this paper , it discusses pain of the metatarsas 2-4 resulting from weight transfer with a dosriflexed first ray, Its a level 3 case control study , scores ok with the mcmaster critiical appraisal , except low sample numbers.
doesn't discuss treatment. -
How about mobilising the 1st met ie it could be jammed in a dorsiflexed position on the medial cuneiform move it thru its range of motion and see if its dorsiflexed position is reduced then post the rear foot or am i being naive?
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I would tend to use the following type of orthosis (see attached illustration):
-medial heel skive
-2-3 degree inverted balancing position and minimal medial expansion to increase arch height
-rearfoot post
-relatively rigid plate material
-make the orthosis 3 mm longer than normal at the anterior edge
-make anterior edge of the orthosis 4-5 mm thick with abrupt drop-off at anterior edge
-make heel contact points 3 mm thick
-use full length topcover, Spenco (i.e. neoprene) preferred
-use 3 mm korex forefoot extension plantar to metatarsal heads 1, 4, and 5 with possible Cluffy wedge
-use soft metatarsal pad posterior to 2nd and 3rd metatarsal heads sandwiched between topcover and orthosis plate
If the Morton's extension is not used plantar to the first metatarsal head, then the pain will not be relieved as well in the plantar 2nd and 3rd metatarsal heads as when the Morton's extension is used. You must try to establish more normal weightbearing function to the first metatarsal head and transfer some of the ground reaction force in the forefoot to the first metatarsal head if you want to get people with this pathology to function more normally, with less pain in the forefoot.
Hope this helps.Attached Files:
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-use 3 mm korex forefoot extension plantar to metatarsal heads 1, 4, and 5 with possible Cluffy wedge
Kevin, Robin wants to off-load 2,3 and 4 not just 2 and 3 that your orthotic design suggests unless I am missing something. Seems like you want the met pad to be centered behind the third met to help dorsiflex the shafts of 2, 3 and 4. Korex under first and 5th only to help off-load 2, 3 and 4th mets. Very nice picture.
Steven -
Nearly always, these patients with a metatarsus primus elevatus will have much worse pain plantar to the 2nd and 3rd MPJs. If pain is significant plantar to the 4th MPJ, which is less likely, then the korex under the 4th MPJ could easily be thinned or eliminated in this type of orthosis. That's why we call them custom foot orthoses!:drinks -
Makes good sense, thanks Kevin.
Steven -
Thanks to all who replied to this post.
My concern as Mike rightly stated was that I wanted to relieve 2-4 MPJ pressure and reduce dorsiflexion stiffness.
As Eric correctly pointed out, there is more than one way of reducing 1st MPJ stiffness than cutting out the 1st met. As such, a medial heel skive and Cluffy wedge will definately form part of the prescription. This will allow me to load the unaffected metatarsals without fear of increasing the internal compression force at the 1st MPJ.
I haven't done any manipulation courses yet so I can't do any manipulations but will definately look out for that.
As I said in the original post, I will probably end up being wiser for having asked the question. I think that I am and I thank you all for your input.
Robin -
Eric -
my thinking was the 1st met was dorsiflexed as it had become jammed on the cunieform ,the guy had said the sub talar joint was medial deviated so mobilise the 1st, sort out the force dorsiflexing the 1st with a rear foot post and the return of 1st ray function would take force/pressure off the rest of the forefoot .Is that a flawed view ?
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Tim,
I think it would take a strong twisting injury with disruption of the LisFranc's joint and in that case there would be a history of such an injury along with radiographic findings, swelling and symptoms.
I do foot manipulation but never saw an isolated jammed first met-cuneform joint and I would think there would be pain in the joint or muscle guarding.
Steven -
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I think there might be a communication break down.
I asked Robin if the goal of the device was to reduce the dorsiflexion sstiffness and reduce the plantar loading of the 2 - 4 met heads. He said it was. One of Robin concerns was the dorsiflexion stiffness at the 1st MTPJ.
I gave a suggestion on the device.
We have callous under the met heads but no diagnosis so until we have a diagnosis it would be harder to say what is the best device I beleive.
Robin if Ive missrepresented what you said please say so. -
When evaluating medial column function in our patients' feet, we must be careful not to only consider the load vs deformation characteristics of the first ray and first MPJ, but need to also consider what is the load being borne by the first metatarsal head compared to the lesser metatarsal heads during weightbearing function of the foot. In other words, we should try to be aware of any evidence which provides us with a better idea of how much ground reaction force (GRF) is present under each metatarsal head during weightbearing activities. In addition, if there is abnormal distribution of GRF on any of the individual metatarsal heads of the plantar forefoot, we need to consider, as experts in the biomechanics of the foot and lower extremity, what we can do to reestablish the normal weightbearing function of each metatarsal head so that 1) pain is reduced, 2) gait function is optimized and 3) no other symptoms or pathology is created.
In the example of the patient with a MPE deformity, where either there is pressure insole evidence, or shoe insole indentation evidence or skin thickness evidence of reduced pressures at the plantar 1st MPJ, one needs to consider that the lack of normal GRF plantar to the 1st MPJ may be one of the major contributors to many of the patient's pathologies. This theory goes back to the work of Dudley Morton (Morton DJ: The Human Foot: Its Evolution, Physiology and Functional Disorders. Columbia University Press. Morningside Heights, New York, 1935) from over 75 years ago. Morton's theory was that a first metatarsal segment that is unable to perform its normal load-sharing function as the largest and most medial weightbearing segment of the forefoot, may cause multiple other pathologies to be created.
Morton described very clearly how his "hypermobile first metatarsal segment" could cause the following functional problems:
1. The 2nd metatarsal head/ray will have “increased burden” since the first metatarsal “fails to assume” its normal share of weight.
2. The foot will pronate because the “medial buttress” is ineffective until “slack in its ligaments is taken up” as pronation increases.
3. As pronation advances, “functional stresses are thrown increasingly on muscles on inner side of ankle, imposing them undue strain” (i.e. posterior tibial tendinitis/dysfunction).
Therefore, since normal weigthbearing function of the first ray is critical, the clinician should focus some of their attention, when evaluating patients, as to whether the first metatarsal head is "doing its job" of supporting sufficient loads of the medial column so that 1) the second metatarsal is not overloaded, 2) the first metatarsal head is allowed to support sufficient load so that normal magnitudes of GRF can be reestablished plantar to the 1st MPJ to generate increased external subtalar joint supination moments that will, in turn, 3) reduce the internal STJ supination moments needed to allow more normal weightbearing function of the foot and lower extremity to occur. -
Tissue stress approach would dictate that the design pictured in Kevin's excellent picture(thanks Kevin - used it today to demonstrate to a patient the design characteristics of his device) would be the most effective way to offload.
Lesson learned in not being clear.
Regards,
Robin -
Hi Robin,
I like the way you think.
For years I would increase the thickness of the orthosis under the first metatarsal head and the fifth metatarsal head. I would sometimes add a metatarsal pad, and sometimes a toe crest. I would also add a heel lift for the equinus if necessary.
For the last four years or so, I just add an equal amount of material under the 2-4th metatarsal heads and additional material under the fifth metatarsal. If this is insufficient to eliminate the discomfort, then I will add a toe crest.
Either way works pretty well, but I prefer the latter.
Regards,
Stanley
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