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Hi, I'm 2nd year UK pod student, just experienced 4th week of biomechanics, looking at 1st ray, discussed why movement is limited etc... We have been encouraged to always look to getting efficient gait with insoles & orthotics and I understand we don't need to change all the pathologies of the foot, just the compensation mechanisms. I realise I have little experience & a lot of learning to do, but what I'd like to know is when there is a problem with a hip or knee surgeons replace them with artificial joints, and try to get normal use back.... so why do we fuse bones in the foot? permenantly rendering them unable to become the 'loose bag of bones' for shock absorption during gait, and potentially inducing further foot pathologies following surgery. Has anyone tried replacing the met heads/ IPJ's with some sort of artificial joints? Is this a silly idea? My logic is it would possibly resume normal function of 1st ray? ... just one of those thoughts that arrived whilst supposed to be doing something else.....

there is something called The Moje, which is a ceramic implant.

Not sure how successful it is though. The only reason i know about it is because i had a friend who worked for a company that used to sell them.

hope this helps

Sam

There are lots of options other than fusion. There is also lots of reasons to choose other options than joint replacement (esecially at the 1st MTPJ).

PubMed is your friend (so is McGlamry's Comprehensive Textbook of Foot and Ankle Surgery).

Hi Mama:
EXCELLENT QUESTION.

Some joints in the foot (and hand) when they become arthritic are just not conducive to replacement. The sub talar joint is a good example. There is no easy way to produce an artificial STJ because of the patient to patient variations as well as the fact that it's not a simple hinge or ball and socket type joint.

Gliding type joints, when arthritic, are more accessible to fusion than replacement, however, replacing the surfaces of these joints would seem a better treatment (if they were available), such as the CC, TN, intercuneiforms. The fact that these joints do better when LOCKED into place during weightbearing than being unstable is mostly responsible for the popularity of fusing these joint. Plus, what else are you going to do if no artificial joint has been designed? If rigid, non painful weightbearing and propulsion is the main objective then fusion of the midtarsal and or STJ's make sense.

The Ankle is really the last of the large joints to give-in to joint replacement. The anatomy and stress forces have made designing an ankle joint difficult. But even this joint is more commonly replaced and, I would predict, will be much more common than ankle fusions in 5-10 years.

Which brings me to the reason I think this is an excellent question: Given the above reasons for fusions in the foot WHY is 1st MTPJ fusions so common? Why fuse instead of replacing?
A replacement certainly heals much quicker, gives better functional outcome and lasts at least 15 years.



Steve

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DrSArbes
Fellow American College of Foot & Ankle Surgeons
Board Certified Foot & Ankle Surgery, ABPS
Green Bay, Wisconsin, USA

Steve,

Do you have much experience with 1st MTPJ hemi-arthrectomy and capsulorrhaphy where a portion of the capsule is pulled through the joint after the hemi procedure effectively providing a "joint buffer"?

Some of the Pod Surgeons in Australia use this technique and from what I have seen short term results seem favourable. Would be interested in your opinion of it?

By far the most common procedure I see from Orthopods down here is fusion.

The reasons I would imagine?

Cost - Measure twice, cut once. Fuse it and forget it.

Effectiveness - minimal need for revision, even after 15 years.

"Do you have much experience with 1st MTPJ hemi-arthrectomy and capsulorrhaphy where a portion of the capsule is pulled through the joint after the hemi procedure effectively providing a "joint buffer"?"

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Hi Paul:
Yes, pulling the capsule or purse stringing it after a Keller type procedure works rather well. If you have a patient who cannot undergo a replacement or fusion or a geriatric hallux valgus/DJD, this is a successful procedure. You can also place a piece of Graft Jacket in the interspace. THis keeps the resected portion of the base from retracting against the metahead (although in time it's going to anyway)

As for the 15 year thing. I've been doing these so long that I'm actually getting some (at least 6 to date) that have been in for at least 15 years and the patients are starting to get a break down of the implant. I've replaced these replacements and they work just fine. Another 2 weeks in a post op shoe and their good for another 15 years - (assuming the rest of them lasts that long.

Steve

__________________
DrSArbes
Fellow American College of Foot & Ankle Surgeons
Board Certified Foot & Ankle Surgery, ABPS
Green Bay, Wisconsin, USA

Are these hemi replacements or totals? Stainless steel or silastics?

Mammatootsies, I hope you're ready for this, as you are based in the UK and this will be relevant to your question!

Ok, here goes.......the MOJE joint replacement for the 1st mtpjt was much better than the previous silastic implants, but this has now, largely, been superceeded by metal-on-polyethylene joint replacements, which are better, however, they can still, sometimes, end up stiff, especially if not rehabbed properly, so can sometimes be an 'expensive fusion' - this is a quote from a Pod Surgeon!

Ankle replacements are also done more now by experienced foot and ankle surgeons and the ones that I've seen back have all been really good.

But, here's the rub..........from an NHS point of view (and this is a current situation where I am in the UK), a K-wire / screw is cheaper than a replacement, therefore, REPLACEMENTS WILL NO LONGER BE FUNDED!!!!!!

My opinion would be that were there are limitations in this technology, surely is better to keep trying, rather than to revert back to old technologies? But that is where you have to stop thinking logically in this game, as the NHS is not logical!

__________________
nicpod1

I've used many hemi's but for the past 15 years I use, almost exclusively, total silastic implants - LaPorta and now Lawrence design.

Steve

__________________
DrSArbes
Fellow American College of Foot & Ankle Surgeons
Board Certified Foot & Ankle Surgery, ABPS
Green Bay, Wisconsin, USA

Oh ok wow - I would really like to see your technique Steve, I have seen a ton of these fail. Granted I imagine it all does come down to good technique & correct/appropriate patient choice.

I was just in the US doing some work and I was astounded as to the differences in approach from the patients/practitioners in Aus to the U.S.

In the U.S. patients/practitioners embrace the concept of secondary surgical intervention. In Australia the concept is shunned, and having to cut twice to get it right is looked upon as failure to a large degree I am sure.

Thanks for your input Steve - its invaluable!

Mama:

This is an excellent question, but is a rather complex subject that deserves much discussion. By the way, Mama, if you gave us your real name to go with your excellent question, it would help inspire others to contribute also.

The question of whether to fuse, or arthrodese, a joint of the foot and lower extremity is not just a question of what will produce the least pain and best function for the individual, but also is a question of the particular surrounding anatomy of the joint and whether it is amenable to having an artificial joint placed into it that will not cause long term problems or sequelae.

In the case of the 1st metatarsophalangeal joint (MPJ), many podiatric surgeons here in the US now prefer the arthrodesis due to it's permanence and excellent function, with a minimal of sequelae and ability of the patient to walk and run after the surgery with less pain and minimal loss in function. Dr. Arbes and I have been around this stump before so I will acknowledge there are plenty of podiatric surgeons that still prefer the implant procedures over arthrodesis and I don't have any problem with this approach. However, in my hands, over my last 25 years of performing foot surgery, I have moved toward preferring arthrodesis of the 1st MPJ as the better procedure for most patients.

The joints that are larger in surface area, such as the hip and knee, are quite amenable to joint implants since the implants are subjected to relatively less pressure (force/surface area) than are foot implants. In the ankle, the joint forces are probably about 2x more than in the hip or knee, but the joint surface area and available bone surrounding the joint that can be used as an interface between the implant and the bone is far less in the ankle than in the hip or knee. The combination of increased joint force along with decreased implant-bone surface area in the ankle implants greatly increases the contact pressure at the implant-bone interface which may lead to degradation of the bone at the implant-bone interface over time and which may, in turn, cause loosening of the implant, requiring eventual removal of the implant and a difficult revisional ankle arthrodesis procedure. The newer ankle implants that use a short tibial rod to provide more implant-bone surface area in the tibia to decrease implant-bone interface pressures, will likely be the future of ankle joints implant designs.

Finally, the question of whether a joint should be fused or not should not come down to looking solely at just the function, or lack of function, of that joint itself, but rather should come down to looking at the weightbearing function of the foot and lower extremity complex, as a whole. For example, if there is too much first ray dorsiflexion/adduction compliance (i.e. too little stiffness) in the first ray, the choice for the patient that works best may be a Lapidus procedure (fusion of the 1st metatarsocuneiform joint) since it increases the first ray and medial column dorsiflexion and adduction stiffness, even though the function of the 1st metatarsocuneiform joint (MCJ) has been totally lost. The redundancy of function of the other joints of the foot surrounding the 1st MC joint will allow the whole foot to still function fairly normally after a Lapidus procedure. Therefore, time has taught us that the Lapidus procedure works very well in many cases since the total function of the foot is improved by the stiffening of an overly compliant 1st MC joint with this procedure.

In regard to the decision to either use a joint implant or a joint arthrodesis, maybe it is best said that one must not lose sight of the forest, by paying too much attention to only one of its trees.

Hope this helps.

__________________
Sincerely,

Kevin

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Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
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