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Functional Equinus

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Romeu Araujo, Oct 22, 2007.

  1. Romeu Araujo

    Romeu Araujo Active Member

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    Hi all,

    I want to do a scientific research study about the prevalence of Functional Equinus. I ask for your opinions regarding the test(s) I should use to achieve it. The test should allow to identify the presence of a Functional Equinus.

    Sometimes I think for myself if I’m not “seeing” too much functional equinus – I commonly observe it (related with compensations) in patients who do sports…

    I have read several articles and opinions about several tests, e.g. Lunge Test, and I quote Kevin Kirby on the thread regarding Lunge test- Please explain... “The lunge test, even though I have no problems with practitioners using it to evaluate patients, does not test for gastrocnemius equinus, does not test for strength of the ankle joint plantarflexors, or for internal derangements of the ankle joint.”

    Thanks a million.
  2. Admin2

    Admin2 Administrator Staff Member

  3. Craig Payne

    Craig Payne Moderator

    The only problem I see is that no matter what test you use the range of motion is very specific to the individual and that varies across individuals. We so over the 10 degree myth.

    Some people only need 0 degrees and function adequately; some need 15 degrees to function adequately; what is needed also varies with speed (some actually need less with a greater speed and some need more); and there is no relationship between what is measured clinically and what is used dynamically (see this from this morning on exactly this in a diabetes population: Passive and active ankle ROM in diabetes)

    Probably does not matter which technique you use, it all depends on what number you use as the cut off point - this will determine the prevalance!

    Also when you ask about functional equinus, what do you mean by the functional? - its just that different people tend to use that term differently? Some people use it to mean the good old fashioned Root defined <10 degree equinus; others use the term to refer to the presence of conditions that put a greater demand on the ROM at the ankle (eg genu recurvatum; plantarflexed forefoot; etc)

    Another question - if you want to do research on this, what exactly is the research question? If it is "what is the prevalance?", then I suggest that you don't do it for the reasons I suggested above. There are plenty of more clinically relevant research questions to do than this. For eg; ankle joint stiffness is becoming the more sexier topic to research than range of motion. Stiffness is essentially a measure of how much force is required to produce a specific range; a pure range of motion test is old news (for eg; I reckon I can get 10 degrees in everyone if I push hard enough)
  4. Romeu Araujo

    Romeu Araujo Active Member

    I use the term functional to refer the presence of such compensations you gave examples of – the typical one is SAG compensatory pronation.

    What kind of device do you use for it?

    I get the stiffness values – ok – but how will I then identify it as pathologic? I mean, how can I know that a X value of stiffness indicates that I’m in presence of someone who has a functional equinus?

    English is my second language – please insist if I did not make myself clear.

    Best regards

    (Please send my compliments to Adam Bird)
  5. Craig Payne

    Craig Payne Moderator

    There are many simple and complicated ways of measuring joint stiffness as opposed to joint range of motion (here is one eg: Decreased stiffness at the ankle joint in patients with long-term Type 1 diabetes .

    I working on a more sophisticated device than a very simple proptotype in the attachment below. You simly use a force guage to push with 10 newtons and measure ankle dorsiflexion; then 20 newtons and measure angle etc etc --- you end up with a force/degree curve --- everyone is very different...... think about this and the standard ways of measuring ankle joint dorsiflexion --> it all down to the force applied!
    No idea!! Its still early days in the research and understanding of stiffness vs range of motion. I know of one project that is looking at this in achilles tendonitis.

    Attached Files:

  6. Atlas

    Atlas Well-Known Member

    Kevin's right in that it does not specifically test for gastroc equinus; as this is done with the knee in extension. Kevin is also right in that it does not test for strength of ankle joint plantarflexion...in fact not many ROM tests assess strength. However, internal derangements of the ankle joint will influence the lunge test adversely. Not only will range be reduced, but the 'normal' physiological achilles stretch will rarely accompany the lunge of a deranged ankle.

    Looking at Craig's device, it looks like it is testing stiffness with the knee in extension; hence the gastrocs are likely to come into play as a passive restraint. With the knee in flexion, this will obviously reduce.
  7. Craig and I first spoke of this problem with measuring ankle joint dorsiflexion and the concept of ankle joint dorsiflexion stiffness at the Melbourne sports seminar in 2005. Using the term "ankle joint dorsiflexion stiffness" ties in quite nicely with my recommendation to eliminate the term "first ray hypermobility" and replace it with the more scientific term "reduced first ray dorsiflexion stiffness".

    In an article published just before the Melbourne seminar on first ray dorsiflexion stiffness, along with my series of Precision Intricast newsletters on the same subject, the idea of using force vs deformation characteristics to describe the mechanics of the lower extremity joints seemed quite obvious to me and, I believe, there will be a growing trend among more enlightened podiatrists and biomechanists to use this same terminology.

    In fact, at the PFOLA seminar in San Diego next month, I will be using the idea of force vs deformation mechanical characteristics to describe the kinetics of the midtarsal joint vs the ankle joint in the measurement of "ankle joint" dorsiflexion and in describing the effects of equinus. After seeing Craig's nicely done and interesting photos, I thought it would be nice to show you all one of my illustrations from my upcoming lecture at the PFOLA seminar on "Rotational Equilibrium Across the Midtarsal Joint: A Kinetic Explanation for Longitudinal Arch Stability".

    Attached Files:

  8. Atlas

    Atlas Well-Known Member

    To get an adequate feel or measurement of forefoot dorsi-flexion stiffness, the more proximal ankle joint needs to be stabilised:confused:
  9. Iain Johnston

    Iain Johnston Active Member

    If I may, add my bit

    I like to beleive that perhaps modern lifestyle ie. sitting watching the telly, driving in traffic, desk jobs, etc have contributed to 'tightening up' of the gastrocnemius. which leads to varying degrees of stiffness or resistance to adequate dorsiflexion for normal gait. Therfore individual compensatory mechanisms depending on STJ ROM, MTJ and 1st MPT motion, will manifest at its weakest link 1st.
    I like to test the patient prone, in 'neutral' and out, leg straight and bent, in order to establish degrees of motion (however after listening to Craig Payne a t a recent conference, I need to factor the new information into my psyche) Negative angles bring up the question of - where do they compensate.
    Perhaps a small test is to get the patient to stand in NCSP. Draw a dot on the tibia whilst holding the pen over the dot let the patient relax the foor, and draw another dot. This will show the extent of internal tib rotation. The do the same with a 5mm heel raise factoring out the potential equinus - the tibia should rotate less, coz of less compensatory demand.

    suck it and see

    Iain Johnston
    Private practitioner
    The Surgery
  10. Iain:

    Is this phrase a mispelling or is this just a phrase that I have never heard before? What does it mean??? Is this a phrase that is said often in mixed company??
  11. admin

    admin Administrator Staff Member

    From Cambridge Advanced Learner's Dictionary:
    "to try something to find out if it will be successful"
    Its a UK thing :rolleyes:
  12. Thanks for that, Craig. It sounded somewhat like an x-rated phrase to me since I've never heard that one before.

    However, this phrase is probably no worse than when I've visited Australia, New Zealand and the UK, and spoke about the little bag that I like to carry around my waist while sightseeing that is called a "f***y pack" in the USA but is otherwise known as a "bum bag" in the UK, Australia and New Zealand.:rolleyes:
    Last edited: Oct 25, 2007
  13. admin

    admin Administrator Staff Member

  14. Romeu Araujo

    Romeu Araujo Active Member

    I appreciated all your comments and agreed with them.:)

    However, my inicial doubt persists – regarding a scientific research study – what test(s) should I use to identify a functional equinus? Or do you think I should drop it off?:confused:
    Should I focus on stiffness?
    But isn’t the clinical consequence of increased stiffness the functional equinus findings?

    Shouldn't we first establish a way of classifying a functional equinus as being so, and then try to understand how much stiffness is needed to implicate a functional pathology as equinus?

    What's your thoughts?

    Best regards,
  15. Atlas

    Atlas Well-Known Member

    Read Danenburg's article on (for memory) mobilising to increase ankle dorsiflexion. I didn't like it at all. It assumed (for memory) that tibio-fibular joint pathology was related to every ankle dorsi-flexion limitation.

    In the day-to-day clinical world, is micro stiffness super-relevant? Is its measurement super-relevant? When considering orthotics, one consideration I have is "Is this mid-foot floppy?". If it is, it is likely to accomodate, handle, and tolerate decent arch height in a device. A rigid midfoot for instance, in a particular type of orthotic, may not allow the 1st MPJ to hit the ground.

    In the day-to-day clinical world, is the quantification of ankle dorsi-flexion stiffness super-relevant? I can't see how it can be more relevant, than "is the ankle dorsiflexion range limited", and "what is limiting it". Are we dealing with a stretch issue (short gastro-soleus and/or posterior capsule) or are we dealing with an impingement/compression or are we dealing with the Danenburg ankle. This Romeu is what needs to be clarified and understood over and above less relevant, but more discussed issues IMO.
  16. Romeu Araujo

    Romeu Araujo Active Member

    Thank you for your reply. What does "IMO" mean?

    Best regards,
  17. admin

    admin Administrator Staff Member

    IMO = my humble opinion
  18. Ankle joint dorsiflexion stiffness is difficult to measure clinically. However, the concept that the foot-ankle complex has a variable dorsiflexion stiffness (i.e. slope of the ankle joint dorsiflexion load vs deformation curve) is critical to better understanding the mechanics of the foot.

    Here are some important points that need to be remembered about ankle joint dorsiflexion/stiffness:

    1. When ankle joint dorsiflexion is being measured in either a non-weightbearing or weightbearing position, not just talo-tibial rotation is being measured but also dorsiflexion of the forefoot relative to the rearfoot is being measured.

    2. Increased ankle joint dorsiflexion stiffness will cause an earlier heel-off during gait and decreased ankle joint dorsiflexion stiffness will cause a later heel-off during gait, all other things being equal.

    3. Increased midtarsal joint dorsiflexion stiffness will cause an earlier heel-off during gait and increased midtarsal joint dorsiflexion stiffness will cause a later heel-off during gait, all other things being equal.

    4. Ankle joint dorsiflexion stiffness will increase with increased ankle dorsiflexion motion due to increased tensile forces in soft tissue structures that resist ankle dorsiflexion (i.e. structures that cause ankle plantarflexion moment) and due to increased tensile forces in soft tissue structures that resist midtarsal dorsiflexion (i.e. structures that cause forefoot plantarflexion moment).

    5. Active contractile activity of plantar intrinsics, gastroc-soleus, FDL, FHL, PT and PL muscles will all increase ankle joint dorsiflexion stiffness. (Plantar intrinsics only increase forefoot dorsiflexion stiffness; FDL, FHL, PT and PL all increase both ankle joint dorsiflexion stiffness and forefoot dorsiflexion stiffness; Gastroc-soleus only increases talo-tibial dorsiflexion stiffness.)

    6. Measurement of "ankle joint dorsiflexion" is highly variable due to varying magnitudes of ankle joint dorsiflexion moment applied during clinical examination by examiner and/or patient.
    Last edited: Oct 30, 2007
  19. Atlas

    Atlas Well-Known Member

    I didn't type IMHO.
  20. admin

    admin Administrator Staff Member

    duh? :bang:

    IMHO - in my humble opinion
    IMO - in my opinion.

    Lots more here
  21. Atlas

    Atlas Well-Known Member

    Good point.

    Don't forget that compressive forces can also impede ankle joint dorsiflexion. Our assessment and understanding of this without radiological confirmation is poor.

    Disagree. This variability of over-stated. The weight-bearing dorsiflexion lunge test, with the foot at 12 o'clock; with STJ coronal plane position given some consideration; with the heel plantargrade; with the subjects' weight in single-leg standing (finger-tip balancing) etc....etc...
  22. What I meant, Ron, was that between one type of ankle dorsiflexion test and another type of ankle joint dorsiflexion test and between examiners performing manual ankle joint dorsiflexion tests, there is considerable variability. However, I would agree with you that a consistently performed lunge test by one examiner is probably fairly consistent.
  23. However, don't also forget there can be no significant anterior talo-tibial compression forces impeding ankle joint dorsiflexion without soft tissue tensile forces resisting ankle joint distraction. Good on ya, Ron!:)
  24. David K Smith

    David K Smith Welcome New Poster

    Dear Romeu Araújo

    When you say functional equinus what do you mean exactly? Restricted ankle RoM or a general restriction of saggital plane progression of the CoM?

    Maybe you would like to discover how many of the population have reduced ankle
    RoM or increased ankle stiffness during walking and if this contibutes to pathological changes.

    How about this as a design.

    To Evaluate the Correlation Between Sagital Plane RoM of the Ankle thru the Stance Phase of Gait and Progression of the CoM through the Sagital Plane

    Measure and record only (Z axis rotation) sagital plane ankle RoM during stance phase. IE use a method that has no ambigutiy about which motion is being recorded. EG Using 3D video (eg Vicon ) measuring the relative positions of the tibia to the calcaneous. also record the progression of the CoM.

    See if there is any statistical correlation between reduced ankle RoM, acceleration and velocity and COM RoM, acceleration and velocity. Additionally you might study the correlation between these parameters and symptoms of pathology.

    Going further you could use a force plate (not pressure mat) to study the correlation between GRF curves and the previous parameters. Further you may be able to look at the sagital plane variations in proximal dynamic joint positions IE hip and knee.

    Because there are no reliable parameters for choosing 'normal' V's equinus, you would probably need between 30 and 100 randomised cohorts to be able to relate this data in terms of population statistics. An exclusion protocol might be x-rays that show any osseous impedance of akle RoM.

    There is plenty of research to review, here's some ref's.

    Ankle ROM and stiffness measured at rest and during gait in individuals with and without diabetic sensory neuropathy.
    Gait & Posture, Volume 24, Issue 3, Pages 295-301
    S. Rao, C. Saltzman, H. Yack

    The purpose of our study was to examine the relationship between ankle dorsiflexion (DF) range of motion (ROM) and stiffness measured at rest (passively) and plantar loading during gait in individuals with and without diabetes mellitus (DM) and sensory neuropathy. Specifically, we sought to address three questions for this at-risk patient population: (1) Does peak passive DF ROM predict ankle DF ROM used during gait? (2) Does passive ankle stiffness predict ankle stiffness used during gait? (3) Are any of the passive or gait-related ankle measures associated with plantar loading?

    Ten subjects with DM and 10 age and gender matched non-diabetic control subjects participated in this study. Passive ankle DF ROM and stiffness were measured with the Iowa Ankle ROM device. Kinematic, kinetic and plantar pressure data were collected as subjects walked at 0.89 m/s.

    We found that subjects with DM have reduced passive ankle DF ROM and increased stiffness compared to non-diabetic control subjects, however, subjects with DM demonstrated ankle motion, stiffness and plantar pressures, similar to control subjects, while walking at the identical speed, 0.89 m/s (2 mph). These data indicate that clinical measures of heel cord tightness and stiffness do not represent ankle motion or stiffness utilized during gait. Our findings suggest that subjects with DM utilize strategies such as shortening their stride length and reducing their push-off power to modulate plantar loading.

    Balance and Ankle Range of Motion in Community-Dwelling Women Aged
    64 to 87 Years: A Correlational Study Physical Therapy . Volume 80 . Number 10 . October 2000

    A device for the measurement of passive torque versus range-of-motion in the clubfoot deformity. Buford, W.L.; Yngve, D.A.; Omid, M.
    Engineering in Medicine and Biology Society, 1993. Proceedings of the 15th Annual International Conference of the IEEE Volume , Issue , 1993 Page(s):1126 - 1127

    Cheers Dave
    Last edited: Oct 30, 2007
  25. Atlas

    Atlas Well-Known Member

    The inversion tilt traction table might be able to assist more regions than just the lower back. :dizzy:

    DR SHAIK NISAR VH Welcome New Poster

    is there any treatments for CTEV other than Ponsetti?is tenotomy is necessary for all cases? is there any complications for tenotomy?repeated casting cuase any problem
  27. Dananberg

    Dananberg Active Member


    Not sure what article you have read....but the one published in JAPMA in Sept 2000was very clear that ankle manipulation will not work when osseous restrictions exist in the ankle joint (page 396, 1st paragraph, right column).

    So, I have no issue with your not liking this article (for whatever reason), but please make sure that if you can't remember details, that you do a prior review before writing comments which are obviously incorrect.

    That said, I have continued to practice this technique daily (as have colleagues around the world) and find it indespensible for managing a wide array of clinical conditions.


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