Welcome to the Podiatry Arena forums

You are currently viewing our podiatry forum as a guest which gives you limited access to view all podiatry discussions and access our other features. By joining our free global community of Podiatrists and other interested foot health care professionals you will have access to post podiatry topics (answer and ask questions), communicate privately with other members, upload content, view attachments, receive a weekly email update of new discussions, access other special features. Registered users do not get displayed the advertisements in posted messages. Registration is fast, simple and absolutely free so please, join our global Podiatry community today!

  1. Everything that you are ever going to want to know about running shoes: Running Shoes Boot Camp Online, for taking it to the next level? See here for more.
    Dismiss Notice
  2. Have you considered the Critical Thinking and Skeptical Boot Camp, for taking it to the next level? See here for more.
    Dismiss Notice
  3. Have you considered the Clinical Biomechanics Boot Camp Online, for taking it to the next level? See here for more.
    Dismiss Notice
Dismiss Notice
Have you considered the Clinical Biomechanics Boot Camp Online, for taking it to the next level? See here for more.
Dismiss Notice
Have you liked us on Facebook to get our updates? Please do. Click here for our Facebook page.
Dismiss Notice
Do you get the weekly newsletter that Podiatry Arena sends out to update everybody? If not, click here to organise this.

Biomechanics of Hyprocure Arthroesis

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Robertisaacs, Jan 4, 2010.

  1. Members do not see these Ads. Sign Up.
    This is an interesting topic which came up in another thread. I thought it deserved its own.

    It started with this article in the daily mail

    Simon Said

    And Dave Said

    What say you?

  2. Re: Hyprocure Arthroesis

    I don't know enough about this operation to make definitive comment. I can see the sense in limiting the range of the STJ to limit the medial excursion of the ST Axis and thus make orthotics more effective.

    That said, like Dave, I worry about the bone the stent is put into. We know the problems we get with bone on bone compression. Will bone on bolt compression cause problems also?

    And can a stent inserted in a child's foot really "last for life?". And will the bone in which it is embedded?

    Another concern for me is this bit

    Is a "low arch" in static WB really "flat feet"? Is it abnormal?

    Informed minds want to know!

  3. Griff

    Griff Moderator

    Re: Hyprocure Arthroesis

    Previous threads on Hyprocure
  4. Re: Hyprocure Arthroesis

    Does anyone know if the Stent allows for any STJ pronation or not ? Is the STJ fixed in terms of pronation? If it does allow some pronation how much. Is this adjustable from patient to patient ? It brings up lots of questions

    I have a feeling that this is another one of those looks great in the xrays so it must be great.
  5. Re: Hyprocure Arthroesis

    I went looking at the other threads and here whats Steve wrote to , see in red it kind of goes against the whole paper peice about Hypocure being a cure for "flat feet"

  6. Re: Hyprocure Arthroesis

    Here's how I see it: we have pronation moment about the STJ axis which, among other things determines the position of rotational equilibrium at the STJ. We don't like the position of rotational equilibrium that the STJ adopts as it's too pronated so we insert a bolt into the sinus tarsi. We now have a different equilibrium position but moments may have changed little; it depends how much the axis would have shifted from initial position of rotational equilibrium to new position of rotational equilibrium. So if the STJ was maximally pronated before and now the patient functions at a new end of range created by the bolt, then the residual pronation moment may have been slightly reduced but, there may still be residual moment = bone on bolt compression. And the patient is still max pronated.

    Personally, I would not be going in the national press advocating this for 8 year-olds, but each to their own.
  7. bob

    bob Active Member

    Re: Hyprocure Arthroesis

    Very interesting stuff all round. I'm not going to claim to be a biomechanics guru or talk in moments or about rotational equilibrium. Bringing this back to very basic terms - which would I prefer - an insole or an arthroeresis? Insole for me, but that's personal preference to a point.

    If I had thoroughly exhausted all conservative treatments such as orthoses and ankle supports, I may then consider this type of surgery. I adopt a similar decision making process for my patients. With any arthroeresis procedure there are potential complications. If a patient refuses conservative treatment, they are made aware of these potential complications prior to considering any surgery so they may make an informed choice (although I recognise issues around consent and practitioner/patient understanding of any procedure) whether they then consider the procedure to be appropriate.

    Certainly it seems a less invasive procedure than other flatfoot surgery and offers many potential benefits when compared. I guess Steve has already commented on other factors governing success in flatfoot surgery so I'm not going to get into that other than to say that any one procedure such as this could not answer all flatfoot problems and needs to be taken in context of the individual presenting on the day and their pathology. In addition to this, would I do this procedure on my 8 year old child given that this particular design of arthroeresis has only been around for a couple of years? No. I've read all the 'anatomic design' advertorials from the company that produce the arthroeresis and I am hopeful that their claims ring true in the future, but until then I would be cautious to only use this type of surgery in those patients presenting with indications for having arthroeresis surgery having exhausted conservative treatment.
  8. Re: Hyprocure Arthroesis

    The subtalar arthroereisis procedure has been done for at least the past 35 years here in the States (Subotnick S: The subtalar joint lateral extra-articular arthroereisis: a preliminary report. JAPA, 64:701-711, 1974). I lectured on the biomechanics of the subtalar arthroereisis a few months ago at a surgical seminar in San Diego and it certainly has clinical application in selected patients since it basically "resets" the maximally pronated position of the subtalar joint to a less medially deviated STJ axis position. However it is not without problems. When I have some more time, I will post my lecture notes for those who are still interested.
  9. Re: Hyprocure Arthroesis

    Nicely put, Kevin. That's what I was trying to say above. The issue arises when the tissues resisting the moments acting about the STJ's new axial position at max pronation in association with the stent are still forced to function in their pathological zones of stress, I guess at that point you use stent + orthoses.
  10. David Smith

    David Smith Well-Known Member

    Re: Hyprocure Arthroesis

    I would be

  11. Re: Hyprocure Arthroesis

    Me too
  12. That seems sensible. It strikes me that this, like any surgery, probably has its place, in which it will do much good, and areas where it should NOT be used, where it could do much harm! I'm certain its inventors are acutely aware of such, however it is a sad truth that once something like this is "out there", especially when it receives such glamorous and glowing reviews in the national press, it will eventually fall into the hands of somebody less careful.

    I can think of a few patients in whom I would consider giving it a go. However the suggestion that it be used prophylactically in children with "low arches" chills me to the core! I look forward to a stream of parents with the cutting in their hands asking if THEIR 8 year old can have one.:butcher:

    It is a sad truth, IMO that whilst many surgeons master biomechanics and use it well, not all do and Podiatric and Orthopaedic surgery has its share of "all pronation bad" type folk. How long before surgeons have a crack at solving a problem which they believe to be caused by "overpronation" by whacking a stent in the ankle...

    PS. Me too Kevin.
  13. Already been there.....:bash:
  14. Assuming that there is translation that occurs between the talus and calcaneus, doesn't the bolt wear the bone away with time?
  15. Bob or Steve or anyone else

    Do you have any before and after xrays you can post with the stent and STJ shown from different views? Would be good to get a look at .
  16. drsarbes

    drsarbes Well-Known Member

    Hi Mike:
    I'd be happy to upload some pre and post ops.
    Can you give me a day? I've spend a lot of time uploading pics today - my nurse is about to throw something at me!!!!!!
    I only take APs and Laterals for the implants.



    Apparently they are pushing the HYPOCURE device in various parts of the world, however, in the USA we call it a STJ Arthroereisis procedure, regardless of the make or model implant selected.

    Kevin is correct in that these have been done in one form or another since the #10 blade was invented.
    When I was a student we would fashion cone shaped implants out of blocks of silicone.

  17. Re: Hyprocure Arthroesis

    I have started a new thread [more general in nature than this thread that is focused only on the recently released Hypoprocure Implant] regarding the biomechanics of all subtalar arthroereisis procedures, for those of you who are interested.

    Biomechanics of Subtalar Arthroereisis
  18. No stress on time when ever you can would be great to see, I guess your still a bit slow on your feet after the accident and can´t dodge flying objects as fast as you used too.

    look forward to seeing them
  19. David Smith

    David Smith Well-Known Member

    From a engineering point of view these shock attenuating devices seem like a better idea than a rigid bolt.

  20. Agreed, but if the subject still stands pronated end range motion (SPERM) and there is residual pronation moment, wouldn't the stent just compress and effectively become stiffer? In so doing the STJ will pronate further, leading to increased pronation moment as the axis medially deviates.
  21. True, but the load rate on the bone around the stent would be slower. Kinda the difference between a rubber door stop and a metal one. They both allow the door to reach the same point but one makes a thump and one makes a bang. Silicon sounds a better idea to me, but then what do I know.
  22. Bone is visco-elastic. Faster loading = stiffer = greater capacity to store energy.
  23. David Smith

    David Smith Well-Known Member

    Simon wrote
    The silicon or less stiff stent could be much larger and so attenuate force over a longer period of time and a greater range of motion but still have the same compression stiffness (or similar) at the same STJ rotation position.

    Robert wrote
    Exactly (the former not the latter Robert)

    Intuitively I agree with Robert but there is merit in Simon's argument too and needs thinking about. I would also add that the silicon stent would tend to deform to the shape of the accommodating surface and so potentially the surface pressure would be reduced relative to a more stiff interface. Generally it's the force per unit area that indicates the tendency to pain and abrasive / erosive wear and tear. Engineering types like to avoid spikes in the force/time integral as they tend to cause more damage (e.g. Force-Time Integral Predicts Lesion Size in Contractile Model Simulating Beating Heart - http://www.endosense.com/site/pdf/ClinicalPapers_ 11.pdf) I suppose someone must have design engineered the titanium bolt concept.

  24. Dave, Robert,

    I generally agree with what has been written. However, other factors such as longevity of the implant will also be significant. A nice gradual deceleration toward end of range is a good idea, but if the silicon stent wears out in 10 years and needs to be replaced this is not so clever. Also, lets assume we use a metal bolt to achieve our initial aim, soft tissues should contract over time and thus be able to provide supination moment which will help to decelerate motion as the joint nears it's new end of range.
  25. David Smith

    David Smith Well-Known Member

    Actually that reference might not be the best example
  26. David Smith

    David Smith Well-Known Member

    As always there are so many variables to consider, but considering wear, wouldn't it be better to replace the soft stent in 10 years than to have to remodel the bony surfaces, which might be damaged and worn by the hard stent even more quickly?
    The soft tissues would contract with either type and this might be fine with the hard stent except that the surgeon is not in control of the maximum applied forces. Can the osseous surfaces withstand the force peak when doing high impact activities as well as they can with the soft stent. One would imagine there will always be a higher force peak with the titanium insert V's silicon.

  27. One thing that got me a little worried is would not the harder stent around the softer bone act a bit like a healed fracture, which may flex more outside the healed fracture and be more likely to develop stress at this point due to the difference in hardness. So then overtime the stent may come lose and not much bone left to work with.

    Hope that makes sense.

    Dave just wrote a new post which says almost the same thing but much better said while I was writing mine !!
  28. drsarbes

    drsarbes Well-Known Member

    Hi Mike:
    Here are your pre and post ops on the last pediatric STJ MBA I did.
    The pre op radiographs are about a year apart. THe post op a few months after the last pre op.


    Attached Files:

  29. Thanks for putting the x-rays up Steve, There does seem to be some change in Joint space between to pre and post op. Good see where the stent travels will study them more closely if my eyes allow it.

    Thanks again for taking the time to put them up.
  30. CraigT

    CraigT Well-Known Member

    What I find interesting in this is the concept of preventative surgery for 'hyperpronation'.

    I have one Italian patient here who had one of his asymptomatic flat feet corrected after getting opinions from several surgeons in his home country. They (the family) were hesitant about getting the procedure, and eventually had it done in one foot first (most of the surgeons wanted to do both at the same time).

    Suffice to say he now does have symptoms in the sinus tarsi of the foot he had the procedure done on- or did do until I fitted him with orthoses to balance the forces around the STJA...
    The visiting surgeon here felt that the implant had shifted and wanted it removed.

    His feet did not appear to me to be anything more than classic hypermobile flat feet- ie nothing like tibialis posterior dysfunction or spring ligament rupture.

    And Podiatrists can be criticised for implementing foot orthotic therapy on asymptomatic children...
  31. drsarbes

    drsarbes Well-Known Member

    Hi Mike:
    Thanks for the link, it's a well written article.

  32. No problems Steve good that you think it´s well written, I thought it was good but I really have no idea no surg in my world.
  33. reckles

    reckles Member

    Re: Biomechanics of Hyprocure Arthroereisis

    Good day all:

    If I might comment on Arthroereisis in general, and specifically in regard to Hyprocure. The biomechanics of the procedure is one of my favorite lecture topics here at NYCPM as it seems to fulfill an innate fantasy I've had- that an internal device can replace, safely, what we do externally. The difficulty as I see it, is in the reasonable application of the device. While I may accept that the hyprocure design is a positive evolution over other devices on the market, I remain concerned that its use occurs without appropriate forethought about why the foot is "pronated", (if in fact that's what it is). Clearly, pathology with a multi-faceted etiology cannot have just one- fits all- solution. In my view, any arthroereisis device, when used in the presence of FF varus, intractable equinus, high tibial varum, Met adductus and any internal torsional deformity of the proximal limb, risks creating substantial post surgical deformity. What is troubling is that many of these procedures are performed simply on the basis of arch height and symptomatology and may ultimately pose problems the practitioner and patient have not predicted- for the lack of appropriate pre-operative assessment. I would appreciate any feedback from colleagues outside the US (where a relatively higher number of arthroereisis procedures are performed). Many thanks
  34. Hey Reckles.

    Firstly, :welcome:. Not seen you before around the board.

    Perhaps you've seen this thread where we see and discuss exactly what you describe.

    And here, truly, is the rub. As Mike described on that thread, the normal style is for the bulk of pronation moment to be generated externally (Gravity via GRF) and equilibrium acheived by supination moment internally (Sinus tarsi compression / deltoid ligament / Tibialis contraction / Plantar fascia / windlass function). Most of the problems we see are in or around these structures so our standard conservative response is to spare whichever of these structures is knackered by generating External supination moment to reduce the amount of internal supination moment required.

    The arthroesis, as you say, generates a significant degree of supination moment by bringing the "meeting point" of the sinus tarsi in much sooner, sparing the other supination generating structures.

    My concern, in the medium and long term, is that the supination moment is STILL being generated internally. Ok so its bone on bolt not bone on bone but the compressive force in the Sinus tarsi still has to meet the demands placed on it.

    So I guess the eligability question is, does the limitation of medial axial deviation reduce the pronatory moment to the point where it will not jeapordise the sinus tarsi. In the foot types you describe the answer will be a resounding no, because the COP will travel more medially than the axis.

    Kind Regards
    PS, Might we know your name Reckles? Whilst not compulsary you will find you are better received if you share your secret identity. ;)
  35. reckles

    reckles Member

    Thanks, Robert, for your comment. And you are correct, I don't usually spend alot of time on this site other than as an observer of trends. I am Bob Eckles, Assoc Prof of Ortho at NYCPM and Dean for Clinical Ed here.

    Reason for my recent query is we recently hosted the hyprocure program here and while, as I said in my earlier post, I feel it makes more sense than other devices which exert their influence, with perhaps more impact related sequellae, outside the sinus tarsi, I left the session quite uncomfortable given that the speakers, other than myself, did not, I feel, fully advise against its use in the circumstances I noted. The device was promoted as a near universal solution to "hyper pronation" which is again a term I am uncomfortable with.

    Hyprocure does alot of business outside the US which is why I wanted to post here to see if clinicians in other countries were seeing problems that have not been apparent here.

    Many thanks
  36. Pleased to know you Prof Eckles :drinks

    It sounds to me as if your concerns are indeed mirrored across the globe.
    You and me both my friend.

    By the by, when did the passe old "overpronation" get replaced by the funky new "hyperpronation"? I must have missed the memo. Means the same but sounds much more scientific.

    To reiterate for the record, when hyperpronation gets old, I've already come up with uberpronation, megapronation, macropronation and superpronation so don't anyone think of passing those off as your own idea.

  37. And we are former classmates and running buddies from the CCPM Class of 1983. Good to have you contributing, Bob!:welcome:
  38. reckles

    reckles Member

    And cheers to you too sir. I vote for Uber pronation myself! I think I can find a place for that in a lecture or two.

    And I will credit you, of course.

    Good day!
  39. reckles

    reckles Member

    Kevin! my best regards to you in the hot hot Sacramento valley!
    I'll do my best to chime in here when I can- makes a nice break from the administrative tortures I encounter. Hope all is well.

Share This Page