The Crispin Colloquy

Brooding further...one other thing that bothers me about this "twist" business is that in some cases it actually is a twist. The forepart of a perfectly good last will be cut and rotated vis-a-vis the backpart...or vice versa.

Which means that the Achilles tendon area of the last will be rotated out of alignment relative to the Achilles tendon of the foot.

Are we "following the foot?"

The other thing...and perhaps someone can help me come to terms with all this...is that we can ameliorate pronation in a finished shoe or boot by adding a medial wedge to the heel stack. Granted, it's rough and ready but it will shift the foot laterally so that the shoe doesn't walk (or continue to walk) out of shape. We can do something similar on the lateral side/heel stack.

Effectively, we are forcing the vector of the line of muscular action to shift in opposition to the wedge and similarly shifting weight concentrations/distributions.

So what happens when we take a normal foot that neither walks to the medial or to the lateral side and add a medial wedge...even if it is in the form of a twist? Don't we force that foot to walk/tread abnormally ("abnormal" for that particular foot)?

My foot naturally pronates. I have no pain nor any trouble walking. And the line along the medial side of the foot is like "a baby's foot"--straight. My line of muscular action probably is just about where it should be--between the 1st and 2nd metatarsal heads. What is to be gained by shifting that line laterally?

I apologizes for asking all these troubling questions...I am perhaps significantly more than several steps behind you, Al...but hurrying to catch up.

Tight Stitches
DWFII--HCC Member

Now we're talkin'!

But, Hey you two,

These posts are so filled with info from both of you, it's hard to keep up. But I'm workin' it.

The discussion of swing has been one I was waiting for. I can see twist is involved. I will be reading carefully.

If I may, I'd like to ask for careful editing, so that each sentence makes grammatical sence. It's all I can do with the concepts, w/o having to make sence of a sentence.

Marlietta, my apologies for my attitude toward you, and the vexation it has caused. You have many good points in your post. I'd like some visuals (from both of you,really), but I don't want to get started on that again.

Peace,
Paul

Hey paul,

I always had faith that you were a good person, we just got started out on the wrong foot. Sorry about that... Peace too..


-Marlietta

Al,

To reply to your post:

===========================================================

"let's take "swing"--tracings, ink imprints,even plaster casts are usually made with the foot flat on the ground; however, as the heel height is raised the great toe moves laterally, incrementally "X" degrees for every "Y" (Korn ave 1/8" increments I recall) of heel height towards the 2nd toe, decreasing the "swing" becoming a more"neutral" shape. If I make or fit-up a last to agree with the customer's foot's "swing" when flat, then add a heel, there's now too much "swing". Thoughts?"

===================================================================

1)casting truly is a matter of preferance. I belive and it was the way I was taught:Casting is only to capture the foot and it's archetecture and a shaping reference not the last. You carve a last from that point forward. If you have a real question as to how the foot will behave in a load and unload position, cast them both ways unloaded and fully loaded at a 90 degree angle to the tibia. However, As I said last time, I disagree with casting in the position of heel hieght with toe spring involved and I said why. To be allowed by your customer to cast in load and unload in one sitting, depends on how you explain it to your customer as to why you need this information. Make them feel special, like you are taking extra care to make sure their footwear fits, and they will be more than willing to be cast twice.

Think of it this way. Some of those on this forum take a foot impression and tracing in a load baring position and others with the foot hanging in the air. Casting is similar. There are casting techniques that an orthopedic, podiatrist, and ped orthist will tell you how to do,as to the proper casting techniques that have more to do with making orthotics than shoes. To long to explaiin here. However, unlike taking a foot impression, Many of these medical casting techniques require an understanding of the biomechanics of the lower extremeities and proper training. This can take about a year or two to fully understand the rippling effect that the mechanics of the feet do to the rest of the body. It is part of pediatry training. If you do not cast properly, you could hinder the person when forming an appliance or footwear from such a casting instead of help them. Once you understand these techniques, than one can learn casting for a last. It's basis is similar but it vears from such to understanding the shaping of a last instead of an orthotic, LLD or any other appliance. One could say it is specialized casting.

However, to try to explain to an ped orthic or pediatrist that you need them to cast for a last, and you do not want to cast ona board with a toe spring on it and they will look at you like HUH???? and they won't understand what you want and will do a slipper cast instead.

Second, to know how much the toe spreds is quite simple, Record by impression how much the foot flairs when placed in it's targeted positiion by making a foot impression in that posiiton fully loaded and simi-loaded. Use lastmakers ink which is a graphite ink. or utilize foot impression paper. The solutions for both are the same. It is just that the foot impression paper is less messy. However I do not like it's information as much as good ol fashioned ink up the foot. You can attain these items here: http://lastmakingschool.com/lastmaking-supplies-for-sale-main-page.htm alternitivly, one can use childrens finger paint and roll it onto the bottom of the foot. The most important thing in taking a foot impression is to have a substance that will mark onto a paper the details down to the swirl pattern of the skin. That is what graphite ink does. This will give you the roll information you desire. these swirl pattern will give you information no other method will. You can see the roll of the toe and smuge mark how much it is rolling out and the like.

Third, the spread of the os backwards will encourage spread of the ball and elongate the arch. cup the os when making an impression unless you don't plan on not having a radiazed featherliine.

Fourth, Mathmatically speaking the great toe supposedly spreads 1 to 2 degrees for every half inch or 1/16th of an inch for every ½ inch of heel hight. However, it is better to get this information from the foot instead of mathmatically trying to attain it. If you forgot to get a foot impresion in it's desired position, than to cover your butt, you use mathmatics. Or that is the way I was taught. Be true to the foot!! was impressed upon me greatly, "after all it is that foot pair that is going to wear the footwear". I buy it.
=================================================

====================
quote:

"In any mildly bunionized feet (so-called "neutral" or "outflare" shapes), IOW c.85+% of feet--if we agree that the 1st met group ought to be a straight line that continues straight through the great toe, with no deflection at the joint, like a baby's foot--the old school approach was to just build the last up/out at the swollen joint. To me this seemed bass-ackward, as by creating a bulging pocket in the vamp for the enlarged joint to settle into would allow the joint to move medially, clipping the great toe more with the upper, and exacerbating the problem. In all events I want to give the great toe room to move back to its natural position without further clipping it. If the great toe has any strength, and forces its own way, either the vamp deforms into a bulge made by the toe (spoiling design/shape), or the wearer's heel tries to walk-over the heel medially, deforming the stiffener/counter trying to escape the straightness of the last/footwear (again spoiling the design/shape).

Thanks for sharing your "secret" too, definitely food for thought."

======================================================

First of all What is IOW???

1) it is now known ( unlike a 100 years ago) that a bunion is not always caused by shoes. I think Fred can go into more detail about this. However, bunion can also be cased by pronation, pronation caused by a faling arch or flexible feet or many other ailments. THE OLD BOOKS WERE OLD SCIENCE. They honestly belived that crimping the big toe caused bunions. It is now known that although tight shoes can be a cause of this, there is other factors.

2) A bunion can not correct it's self on it's own! As a shoe maker one should not agitate the problem, but, if a toe is already almost crossing the second toe, making more room in the toe box near the toe isn't going to correct the toe or give it more power................

Major manipulation and elongation of the ligments or surgery is required.......................

So you shouldn't clip the joint but, if you follow the position of the toe, you arn't going to damage it or limit it's power. Trying to naturally correct a bunion by allowing the first toe extra room is old Meyer's thinking, old science................

When a major bunion has already occured,, the ligiments are actually not helping the bunion but causing further tightend bow string effect down the center of the area inbetween the first and second toe pulling the toe into that position. The joint if inflamed will be painful and the little pea size bones are moved over to the medial side will add extra width. Then you have a further problem if you have a hallux rigidus which is when the the large toe joint is stiff.

So my point is.....A shoe that follows the line of the bunionated large toe as it vears towards the second with normal sole shape clearance and not clipping it, will not hurt the foot any further nor will it render it powerless. It already is limited by it's position and the tightend ligiments.

====================================================================
Quote:

"OK, now to"twist"--as the heel of the foot is raised (in gait or by an elevated heel), flexing across the angle (variable) of the met heads/joints, the medial side of the heel raises higher "faster" than the lateral side. Some really good lasts reflect this by mimicking
this "twist". But a tilted heel-seat plane is hell in machine lasting to build a shoe on, and even bespoke makers whine and moan because it
necessitates added care in making the heel-seat, and then the heel, to avoid the cosmetic "problem" of a finished heel that's higher medially than it is laterally. Factory lasts often have insufficient "twist", or none at all, so when the shoe is on it effectively thrusts upward under the lateral side of the heel, inducing the foot to pronate, dumping all its weight onto the medial side. Again, this bugs me because we know the lateral side is the "stronger" weight-bearing side
of the foot, and flat un-twisted lasts (and footwear made on them)shoves everything onto the weaker medial side, overloading the 1st met
head/joint and other evils. Again, it's a ontrol-factor that must be adjusted, and IMO no last's heel-seat transverse plane ought to be dead flat, in the same plane as the transverse plane in the forepart. (Ouuu, rough sentence, but I hope you get what I meant).

There are some splendid old lasts out there, designed by folks who knew their trade and who controlled all of these factors like we adjust the vol., bass, treble, on a hi-fi. I'm just afraid it's a matter of "lost" skills that we have to recreate, first by being able
to "read" the old lasts, then by systematic analysis of which "knob" affects what sound coloration, and then how to dial-in the knobs to
get the sound just right."
=======================================================================


1) This is a good time to refer to a post Bill Tippit did on the raidiazed ball. http://www.thehcc.org/forum/viewtopic.php?t=7338

He was discussing why the ball of a last is rounded a the bottom. I was taught that
1) it is because the relaxed foot is rounded too.
2) nature intended this for flexation but also for propultion and twist. The amount of roundness balanced with the heel creates the twist. this round ness is important to make sure is balanced with the arch of the metatarsals. So you don't encourage the failing of the met arch but encourage perpultion in gait.

If you cast a foot load baring, alot of this roundess disapears. and thus the information disapears unless it is a very young foot.

To really sight this, see three foot models all non load baring at different ages and you will note how this roundess goes away. many twist issues as i was taught is actually age related, or mechanics of the person relation or both. You can find a lot of your twist answers in what makes a forfoot varium or valguas. Additionally, I get your complaint and understand it. However, I think you might find further answers in biomechanics of the lower extemities. You have studied lasts already and obviosly know your stuff!!!!! . Now if you balance the study of last with what biomechanics tells you, I am pretty sure you will find your answer there and then the mystery of the "old timer knows all" might be revieled to you. I guess my thought is, think of it this way, for the foot pair in question, how much forfoot varium or valgus do you need to create a balanced last?????? Do you need the twist????
=======================================================================

give me a hunk of wood, a sharp rasp, and sit
me in the corner......Maybe if I got into CAD
I'd be half-dangerous in the last world *Bwahahahaha* ?????

-----------------------

me too....


Marlietta
Lastmakingschool.com

D.W

I truely belive that twist and the question of twist, as i said earlier to Al, the answers lie heavily in " how a balanced orthotic is achieved. You can balance a last like the ped orthist balance an orthitic. Think of it this way, many production lasts do not have twist, but then an custom orthotic introduces twist to the shoe. this becomes an issue if the foot is already twisted and then a custom shoe is made on a none twisted last. The foot wil eventually twist the shoe in the desired position. with out the orthotic. however, with the addition of the orthotic, the shoe becomes to deep. and vamp lines and seams do not line up.

I'll see if I can find a twisted shoe to show you an example of what I mean.

Thus, if you introduce a twist "correction" into the last, you can have a balanced footwear.

If the foot creates a for foot varum or valgum IN ANY POSITION than the last will need to be twisted to assist in correcting this for a balanced gait.

I belive Fred, if willing, can elabrate on this further.

-Marlietta
Lastmakingschool.com

P.S. Further About twist.

For a healthy foot that shows no biomechanical issues such as forefoot valgum or verum, but you want to introduce twist for functional control when forming a new last 1.5 inches-2.25" you begin the twist at the instep ever so slightly not at the forefoot! If you only twist at the forefoot, for these heel hights by the time the foot falls on the forefoot, it will introduce to much suprise to the foot and could cause the ankle to twist and sprain. OOOOOPPPPS!!! then again...if you don't like your customer...... Seriously, done on purpose would be mean.

This is not to say that you cut a last at the instep and turn to introduce twist...... for that will introduce to much twist! You introduce is ever so slight while shaping. It is a very easy and slight encouragement of the foot towards the lateral side to hit the center of the lateral little toe and then for the radiazed ball to tip it further towards the inside for toe off, but again, this must be in balance with the natural long arch. Further,the curvature of the fat pad area which will assist in the natural function of the foot for it's natural cycle of pronating before it toes off. This is a design control area.


I was taught that the footwear is a covering to work with the foot not work against it. It should behave like a glove on a hand and a person should forget they have shoes on. 2.25 inches and you are walking on fat pads... so help the person do so, 6" and who cares about twist!! your walking on your toes.

Some times the elevation of the roundness of the fat pads at the bottom is mistaken as twist. If you site a last down center and you see a twist only at the fore foot and it begins to rise at the little toe and decends past the center of the large toe, this is not twist, this is a radiazed ball. Again, one would need to observe non load castings of different feet and compare to current lasts to get this visual.

So twist is a wieght distribution mechanizem for control of footwear function.It is not a radiazed ball. However, it isn't always required for a healthy foot either. It can be "a matter of design" for control and function.


Think of the healthy gait cycle of: heel strick, supinating roll out, roll in and toe off.... When designing and forming a new last you repeat to one self"heel strick, supinating roll out, roll in and toe off" as you are shaping. How is your footwear you are desinging going to achieve this end in it's current position????? Do I need to introduce twist, forfoot roundness or will it behave the way I want just as it is???

Just a thought.


-Marlietta
Lastmakingschool.com

(Message edited by Last_maker on November 18, 2010)

(Message edited by Last_maker on November 18, 2010)

/image{picture} Well Paul, I followed the directions. I tried to post a pic, sorry, It just didn't work. I guess I was not ment to post pics. I give up!!

I am using internet explorer

I wanted to post a pic of an an example of a bunion that can not be corrected through a loose shoe. But as I said eariler, a last, thus a B/S sahpe should not agtitate it either. This bunion deformity has already dislocated and the ligiments are now to strong in thier position to be effected by a B/S toe box shape.

Therefore, a custom lastmaker, or a B/S maker they may follow a toe box outline as desired clearing the joint and toe.

I Love Bernard's example drawing that states, if we were ment to have our shoes shaped like a "tailors swing" our feet would look like his drawing!

Marlietta
Lastmakingschool.com

(Message edited by Last_maker on November 20, 2010)

I think one must be extremely careful and knowledgeable when introducing twist to the last. (which subsequently the foot will follow in the shoe). There has been no mention about "fixed" rearfoot(rf), forefoot(ff) deformities nor flexible rf or ff compensation. Not to mention position and gait issues higher up the kenetic chain. Without thorough understanding of these aspects of the foot in gait, one is better to create a neutral last with room to use medial or lateral posting within the finished shoe, which is more readily adjustable to the client's condition.
Varus, valgus foot positions may be patholigical and best addressed with medical advice.
Just a humble cped's opinion.
David

Well Said David! I totally agree!

I honestly belive that todays lasts which are mainly neutral and are with out twist are a safer last in this regard and are more user friendly for boot and shoe makers.

------------------------
quote:

" neutral last with room to use medial or lateral posting within the finished shoe, which is more readily adjustable to the client's condition."

++++++++++++++++++++

I totally agree.

Marlietta
Lastmakingschool.com

It was not my intention to dampen the zeel in this most interesting thread, but just to point out to those of us who may be practiced shoe, boot, or last makers -to some degree, that there may also be serious orthopedic biomechanical consequence to manipulating gait through our last making.
Observing what appears to be a varus or valgus relationship of the plantar surfaces of the feet does not necessarily tell the whole story of a client's gait, and may not dictate the need for twist in the last.
I do not feel qualified to determine how many degrees of twist may be appropriate. But do not doubt other's abilities to do so. And am fascinated in thinking out the process of working with and making footwear on twisted lasts. So I hope this discussion continues and points up a few more gems that may have been lost with our trade's predecessors.
David

Marietta,
You almost got it right. Just use the back slash, instead of the forward slash.
as in, .
Don't give up now.
Paul

Well...just use a bacl slash instead.

DW,

Cotes du Rhone perhaps?

"Hide the Decline"--from the insole up to the top-piece of the heel, make your entire heel-seat with an eye towards minimizing the higher medial heel height cosmetically. If you last the quarters (stiffeners, etc.) under, when you skive or pound them to settle, go heavier on the lateral side. When you fill the seat, cover the shank-piece, etc, "level" the new bottom. When you lay-on your outsole, split-lift, and each successive lift, "level" each with your big bench rasp as you go. By the time the top-piece goes on it should be nigh unto level in appearance, even though the insole is "twisted" to the last inside.

-----------------------------------------------------
"but I haven't seen tilted heel seats even on the exemplars of bespoke shoemaking."
-----------------------------------------------------

Exactly, you shouldn't "see" it. You know the trick though from bootmaking and shoe repair--if a fellow walks a boot over to the inside (pronates), you grind the 2nd-to-top-piece lift off sloping on the sander then pop on the top-piece. In shoe repair, you add a slight wedge of leather to the heel on the medial side to "twist" the rear foot up. All a "twisted" last does is achieve the same result, only from inside the boot or shoe with less of the effect showing in the finished heel. Make sense now?

Like I said earlier, the "twist" of the foot is exaggerated in higher heel footwear. Men's bespoke shoes with their 5/8" heels need less twist than, say, an 1 1/2" heel or more. Also, for some feet the angle across the joints is smaller, so the rear foot raises closer to (but never completely) in the same plane as the joints. In all events, inside the footwear the medial insole surface could generally be 1/8" + higher than the lateral surface to great effect.

A good test is to set your last on a table and depress the toe to bring the back up to heel height and look. The center-line up the back of the last should now be listing ever so slighting to port, and the feather-line of the heel slightly higher medially. Nothing too dramatic. That said, I have several old small runs of factory lasts from Musebeck Shoe Co (courtesy of Walrus Shoe) that have the highest medial twist I've ever seen. In fact I have no idea how their factory made on them the heels are so "twisted"--the guy at the seat-lasting machine must have hated trying to wipe the quarters over them. The dates on these last range from 1939 up into the 1960s, and they were well used, so they were not a one-off freak, but a popular last in production for 30 years.

Let's consider the opposite, no twist, and a heel-seat in the same plane as the joints, like the majority of factory lasts (Dan Freeman calls these "upside down aircraft carriers"], totally dead on the bottom and the definition of center cone. Again, in higher heeled footwear, the effect is the lateral side of the heel and waist will be thrust upward laterally, and there will be nothing inside to support the medial rear foot as the heel is raised, inviting the foot to pronate. Where's the sense in that?

Marlietta,

Wow! Like trying to take a sip of water from a fishing fire hose here. "IOW"=in other words.

I've had limited experience with plaster casting except those foam foot boxes to do plaster casts in for making mild orthotic inserts, and zero pedorthist training. Yes, I miss Fred on this... Fred, you out there?

So far, touch wood, I've not been presented with any extreme textbook bunions, with toes piled-up or huge swollen painful joints. My main concern is just not to clip the great toe inviting them. I had this discussion with an old HCCer orthopedic Dr. from a foot clinic in GA, on whether hanging from a tree limb for a lifetime would bunions even occur? He said yes, which I found troublesome. Some physical force has to open that 1st met joint FIRST, inviting nature too fill the void with calcium deposits, etc. I simply do not want my lasts/footwear to do the inviting is all

So you're saying, "mathematically" the great toe naturally moves laterally, toward the center-line of the foot, 1/16" for every 1/2" of heel height? So in a 1" heel the great toe has moved 1/8" from its flat barefoot position, so a last could theoretically "clip" 1/8" off the barefoot tracing safely? The foot before us naturally is the best guide, but generally speaking.....?

Granted, no bunion is going to go away because of medial toe room in a shoe, but my point there was simply not to exacerbate it. And in certain "mild" cases--my wife's for example--after extended wearing of nicely "swung" shoes, relieving the force, her great toe repositions and her 1st met joint feel much better. Shoes may not be the only culprit in bunions, granted, but toe shapes and uppers that "fight" the great toe cannot be doing it any good. Thoughts?

To quote a grand old man I know: "feet are like water-balloons with a skeleton inside, and never the same exact size twice in the same day." This renders some of this precision futile. What I mean is this, take the natural deep footbed that a foot will make for itself in a good leather insole with cork infill through wear. It is a blur. It's not the same crisp footbed we might create artificially from a static foam box impression, but rather captures the foot in its full range of motion over time--it's more "smeared" than what a plunge into foam might create. All of these methods we use to capture data from the foot, it seems to me, are mere snap shots or "frozen frames" of the static foot, and not fully reflecting the "blur" that is the foot-in-the-footwear. But I digress....

Marlietta & David,

I concur fully; however, when a customer puts on a new B/S and I ask if they feel any more upward thrust under the lateral midfoot and heel than the medial, if they say "yes", I goofed big time IMO.

Just to be clear here, I'm not advocating any dramatic "twist" be introduced without consideration, just that the vast majority of "factory" lasts have zero, ought to have some, and no footwear should throw the foot's weight directly from heel-strike straight to 1st met head, on the "weak" side, because of lack of any "twist".

Al,

I hope you don't mind if I "shmooze" you a little bit and say that when it comes to lasts, I look, and listen, to you as no other.

So I wasn't going to respond to your last couple of posts...I simply don't know enough.

But that doesn't mean I don't know anything and what I do know has me bursting with questions and a bit "a-hoo" as who should say.

TWIST

First, I have always felt that the Line of Muscular Action (LOMA) was probably one of the most useful tools we have in our arsenal. I don't fully understand it in all its ramifications even after all this time, but once upon a time I understood vector mathematics pretty well and the LOMA falls neatly into that category.

Putting aside the fact that we all tend to build shoes/modify lasts as if all feet were like our own feet, I don't see anything in your explanation above that addresses LOMA.

Raising the medial heel shifts LOMA...we can argue about whether that is good or not, I suspect in some cases it is not only good, it is therapeutically indicated. Lowering the medial heel shifts LOMA.

But the foot tends to have a natural sequence of motion completely divorced from shoes or twists. The foot will want to...try to...follow that sequence no matter what you do to the shoe or last. Eventually, I suppose, we can modify that sequence by alterations to the last or with orthotics, or at least we can correct a faulty sequence. Nevertheless, in every case it is really the LOMA we are affecting.

I see twist as affecting the LOMA even if the twist is slight. Sure, we can force the foot into a slightly unnatural sequence without much in the way of consequence. the foot is a wonderfully adaptable mechanism designed to provide stability and balance in all kinds of variable terrain. But we are still forcing it just as surely as when we put a foot into a shoe that is a half size too short in the shank (heel to ball).

I cannot see the benefit of raising the medial heel if doing so shifts the LOMA laterally from between the first and second metatarsal heads to directly under the second metatarsal head.

I wish that you would address these issues for me...at your convenience, of course.

Tight Stitches
DWFII--HCC Member

David,

I honestly belive that a person just learning last making, should study in depth the biomechanics of the lower extremties and the the ground force reaction to the foot.

Now I am sure that many have successfully made lasts with out such detailed training, but i belive this understanding makes for better last designer and a confident last maker.

Marlietta
http://lastmakingschool.com/classes/LastMaking101course.htm

COSMETICS

Well, here is where things really get dicey for me. I am naturally conservative and tend to hold certain standards of symmetry as nearly sacrosanct. (It compensates for my lack of artistic talents)

It seems to me that any alteration to the heel stack will only compound...or negate...the effect of twist. If we try to reduce thickness on the medial side of the heel stack to bring the heel seat level, it negates any effect that the twist imparts to the foot simply because it will shift the LOMA to a point ,ore nearly under the first metatarsal head.

So, on the shoe, we end up with a heel stack that is level and a forepart that is "twisted"--with the lateral welt riding several degrees/millimeters higher than the medial welt.

It's not a balanced look.

About the only thing that I can see being done that would have any purely cosmetic effect is to skive the split-lift thinner on the very edge of the medial side. Maybe the same could be done on the very edge of the outsole. I say "the very edge" meaning an area where the outsole or splitlift is not directly under the heel seat of the foot.

Either of these raises its own problems--among those getting the split-lift to align with, and be the same thickness as, the welt--but I would accept that someone far better than I could pull it off without trouble. After some experimentation, however, I have come to the conclusion that I would need a full blown seminar to understand, much less become skillful doing that.

So...I come back to wondering if allowing the forepart of the shoe to be twisted out of the natural plane of the last is the correct approach. It seems counter-intuitive to me but one could, I suppose make the case that the foot itself will set the forepart straight.

Am I on the right track or not so much? Barking at shadows?

Tight Stitches
DWFII--HCC Member

DW,

I blushing. I have to say that I have a good grasp of LOMA, from having gone back and forth with you over the years; but to my understanding LOMA has mostly to do with swinging the toe shape of a last medially on an imaginary line that is closer to the lateral side of the great toe than the 2nd toe, like most toe-clipping factory lasts are designed. Following LOMA can eliminate toe-pinching/clipping.

Adding a little "twist" to the rear-foot of the last is all I'm talking about, to counter the footwear forcing pronation.

-------------------------
"I cannot see the benefit of raising the medial heel if doing so shifts the LOMA laterally from between the first and second metatarsal heads to directly under the second metatarsal head."
--------------------------

You are using LOMA as a more rigid guide than I do. When standing "still" weight should be felt evenly distributed on the tripod of heel, 5th, and 1st (and great toe) with no up-thrusting "log" felt under the lateral rear foot. If a boot or shoe presses upward on the lateral side of the rear foot so there's more weight thrown into the 1st and great toe, then we goofed. That's all. In walking, too, if the footwear steers the foot away from the stronger lateral side of the foot, and too hard onto the medial, trouble results. Remember: 1) heel-strike, 2) weight travels down the strong lateral side to the 5th, 3) then rolls across to the 1st 4) and the great toe pushes off. Insufficient "twist" (and other factors) change this from 1) heel-strike, to 2) dumping weight onto the 1st (by-passing the lateral side and 5th, etc.) short-circuiting gait.

Or ask this: what's worse, enforced/exaggerated pronation, or a tad too much supination? To err towards supination avoids overloading the arch preserving natural gait, and if it overloads anything, it's the strong side of the foot--like your old adage, "if you gotta fit wrong, fit long". We don't want people twisting ankles, running vamps over at the outside joints, or falling off heels to the outside either. But, from what I've seen, most lasts and footwear induce over-pronation, rather than over-supination, so they are unbalanced IMO. Maybe, then, what I'm calling "twist" here is really more just a matter of bringing a last back into a "neutral" balance, which usually necessitates a little medial lift.

DW,

Okay, maybe I'm painting poor word pictures. Clean slate, let's try this: I'm a firm believer than any/all anatomical architecture as one might achieve through an excellent orthotic insert device ought better be sculpted directly into the (custom) last itself. With such an overly "lively" anatomical last, building a B/S is going to be complicated, but the trick is to have the foot compartment (container shape), especially the insole, anatomical (as per an orthotic), and the outsides of the B/S "normal" looking. All this requires is care when leveling/filling the bottom, and layering the outsole, and all the subsequent heel lifts, that's all.

Radiused feather-lines, footbeds, "twist", etc. should be in the last. If you make a B/S over-sized, "extra depth", dead container shape, then try to make an appliance to slip inside seems counter intuitive. As B/S makers with a modicum of last-tweaking abilities, we ought to do all that to the last, so these architectural features are integral with the footwear. Slipping in an orthotic is a compromise. The devices slip, slide, are not a rock-solid part of the footwear, etc., etc., etc. Seems to me--and no disrespect is intended to our c-ped/pedorthist pals--but a decent B/S maker ought to be able to create the same "appliance" effect by manipulating the last, so the footwear has these corrections built-in.

If you close your eyes and fondle a nice last, it should feel like you are holding a human foot with a stylized toe shape, IOW very anatomical on the bottom, proto-footbed carved in, and round and radiussed in the back part. Such lasts are harder to built a shoe on, especially in a factory, but by livening-up the last anatomically, the need for inserts to achieve the same results are mitigated. Look at the over-the-counter inserts, most all they do is fake a radiussed feather-line, add a little "twist", and "blind" your propieceptors with too damned much cushioning so folks plod along like pregnant Yaks like they do in modern sneakers IMO

Al,

This is helping...from this most recent post I am understanding that twists are not for every foot...only those that tend to pronate or supinate inordinately or unnaturally, ie. due to an inherent weakness in the foot structure or pain, etc..

Is that right?

Because as I tried to illustrate in my earlier post to the forum, my foot pronates...I have a low arch but my foot is straight like a baby's foot, I have no pain and I tend to walk and balance in the right places underfoot.

I found the West End last with the twist annoying, at least initially. I felt the twist in that last. (My wife who does not pronate felt the twist as well.) It's not painful...I wear it every day and I'm OK with it but it raises the question: if it was annoying at first, was it appropriate? Either the shoe has broke in (my guess) or the foot has broken down. It's interesting to note, that my feet are still comfortable in other shoes/boots that do not have the twist.



Tight Stitches
DWFII--HCC Member

PS...tieing up a few loose ends...

LOMA to me is an averaging out of the sequence of motions--the direction of weight shift--over the course of natural gait. It is not a straight line...it simply says that the end result of that crazy zig-zag of weight shift should be a directional force and weight distribution that ends up being focused between the first and the second metatarsal heads--in a healthy foot.

Also, I am not so sure that the lateral side of the foot is the strongest side. No more than the lateral toes/met heads are the strongest. The bone structure on the medial side is heavier and the most important function of the arch (with its heavier bones) is to further buttress the medial side. Fins and fans and feet all share this characteristic--one side is the buttressing side, the other moves more water, carries more weight etc..

Feet, fins, etc., generally have more bones on one side both for flexibility but also, in conjunction with that, to balance the strength of the buttressing side. Do you follow?

The lateral side might, in aggregate, be as strong as the medial side but if the bones were as heavy and the lateral side as heavily arched we would stump around like pregnant Yaks.

Tight Stitches
DWFII--HCC Member

(Message edited by dw on November 21, 2010)

One other thing...I am in agreement that a good maker ought to be able to do everything that a pedorthist can do in the last rather in a the form of an orthotic. And the result would/should be much superior.

I'm not that good...probably never will be...but in theory that's the way to go, IMO. I like your allusion of holding/fondling a last although this could get X-rated pretty quickly and not suitable for public viewing.



The last is the beginning and end.

Tight Stitches
DWFII--HCC Member

DW and Al:

This is a really interesting topic.

Given the fact that the medial part of the foot is higher when the foot is elevated, it makes sense to me that the heel seat should be twisted as well. Don't we want the foot to be in a neutral position in the shoe? And, if so, it thus makes sense that the medial heel should be a bit higher, since that would seem to support/hold the foot in a neutral position.

I would think about it this way: if, instead of wearing shoes, we merely were to stick/glue a heel piece under our foot, then walk around like that, wouldn't we want the heel piece to be higher medially? Otherwise, the foot would either collapse toward the medial side, or alternatively the contact with the ground and hence all the weight would be on the lateral side. Neither outcome seems desirable to me.

DW: how is it that the twist/elevated medial heel seat shifts the LOMA, and assuming that it does so, how do we conclude that it shifts it to an undesirable location? (This is a sincere question -- my understanding of the biomechanics of the foot and walking is woefully lacking.) Might it be the case that the absence of a twist in the last (and consequent shoe/heel seat) actually throws the LOMA too far medially, and the twist actual restores it to the desired vector?

Regarding hiding the twist, Al, your comments are really helpful. I am personally not so bothered by the thicker medial portion of the heel, but in my next pair I will try to do more 'inside' the shoe -- i.e. the counter, insole trimming, etc, to see if I can make the medial/lateral discrepancy less visible.

I think I mentioned to DW at the AGM that Terry Moore told me that he believes what distinguishes his lasts is that he puts more shape into the bottom than the other folks in London. Thus, this discussion is really interesting to me.

Thanks for everyone's input on this topic. It is great.

Lance,

Do you ever do a pedograph? A footprint? I do them for every foot I measure. I don't recall seeing a foot that did not print more or less evenly across the whole of the heel/heel seat area unless the foot exhibits pathological characteristics.

What does that footprint represent? It is a weight-bearing representation of the plantar surface of the foot. Which in turn represents the weight of the body being transmitted down the leg and into the structure of the foot--with the os calcis taking most of the initial load and distributing it through the arch and tarsal to the fore foot.

It is like a bridge or an architectural arch. If weight is not distributed evenly...not balanced...the arch fails. If the medial heel is lifted such that weight is shifted away from the center of that Os Calcis and the Tarsus Seven then the longitudinal arch cannot take its share of the weight, cannot distribute it evenly towards the toes and the foot is not in balance.

Sure we can lift the heel relative to the toes and observe a "twisting of the foot such that the medial heel seems elevated. But this is not a weight bearing observation and really has little significance in my opinion.

LOMA...as mentioned above...is Line of Muscular Action. It is a averaging of vectors. But it is also a recording of weight distribution during gait. Which is why it necessarily comes out between the first and second metatarsal heads--neither overloading the first nor the fifth.

If weight distribution is thrown off to the lateral side initially the foot will not be able to recover in the space and time of a footfall and the LOMA has to shift laterally.

As far as hiding the twist--I have tried...really tried...but my observations and experience, limited as they may be tell me that any modification to the insole, heel stiffener or outsole...any thinning or lowering...that is directly in line with the heel seat, will simply negate any effect that the twist may have imparted. You may end up with a level heel seat but you will end up with a canted forepart.--the LOMA will have shifted medially.

Look at a last that has the medial heel twist...if it is set at heel height with the heel seat level--parallel to ground(as viewed from directly behind the last)...the forepart of the last will be canted medially. If the heel seat of the last is set so that there is more distance from ground to the medial featherline around the heel than there is from the ground to the lateral featherline around the heel, then the forepart of the last will be balanced somewhat medially from dead center.

And if I understand the concept and the objective, it is just this latter configuration that is wanted. The whole point, after all, is to introduce a "lift" under the medial heel of the foot.

If you want to see this in action take a last that you consider "dead," as Al puts it...or "neutral," as I prefer. With a grease pencil draw a line down the center of the heel seat. Draw another line roughly...what?...say 3 mm along the medial side of the heel just above the feather line. Now file or grind a wedge of material off the bottom of the last such that these two lines...one in the center of the heelseat and the other on the medial side of the heel...are connected (clumsy way to say that--just grind a plantar wedge from the bottom of the heel seat.)

Now put it up on an eye-level shelf and consider all that has been said--especially with regard to balancing the shoe.

I am sure that I am preaching to the choir but a last...and necessarily a shoe or boot...must rest at a very specific point on the treadline (that's what a "treadline" is, after all) as the shoe is viewed from the side; and a very specific point as viewed from the front. And while it seems that where that point is relative to the forepart is open to interpretation, at least in the context of this discussion, the pair of shoes should at least match.

Hope that makes sense.

Tight Stitches
DWFII--HCC Member

(Message edited by dw on November 21, 2010)

(Message edited by dw on November 21, 2010)