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Measuring LLD

Discussion in 'Biomechanics, Sports and Foot orthoses' started by DrLCT2, Aug 19, 2005.

  1. DrLCT2

    DrLCT2 Member

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    <>Admin Note: This message has been copied of the Normal Foot thread as it worthy of its own topic </>

    Quote Ian:
    "In terms of Leg Length Difference (LLD). My experiences of working with physios suggests there are a number of ways of assessing this but that real accuracy requires X-ray (please correct me if I'm wrong) and that anything short of this has, as you say 'errors'."

    In our Clinic and Laboratory, we use many clinical ways of assessing limb lengths:

    1. With the patient sitting (legs extended and supported, feet dorsiflexed) we compare the relative lengths of the legs by checking how the plantar aspects of the heels and the medial malleoli relate.

    2. With the patient lying supine, we do the same as above.

    3. With the patient lying prone, we do the same.

    If we suspect a Leg Length Discrepency (LLD), we'll then measure the limbs doing:

    4. Apparent leg length measurements with a Tailor's tape measure - measuring from the umbilicus to the same point on each of the medial malleoli.


    5. True leg length measurements with a Tailor's tape measure - measuring from the anterior superior illiac spines of the pelvis to similar points on the medial malleoli.

    6. Check posture (front and back); i.e., for shoulder droop/drop (often on the long side), hip elevatus, etc. .

    7. Checking gait for limp, unsteady gait, more pronation one side vs. the other, etc. .

    To confirm our suspicion of a LLD, (and you're right, it's the most definitive way) we'll then order scannograms (sometimes spelled scanograms). In the good old days, these were flat plate X-ray studies done with the patient lying supine with a metal tape measure placed beneath their leg from pelvis to heel. Spot X-rays were then taken of the hip, (of the knee if you'd like to know at what level the shortage occurs), and of the ankle. The radiologist would then calculate the leg lengths on X-ray; however, for some of them, their math (adding and subtracting) was terrible - so it was always best to check the films yourself and do your own math! ;)

    Nowdays, the radiologists use CT and let the computer measure the leg lengths for them. I still prefer the older method (but have gone along with the times) but think the results/answers I got were much better using the old X-ray method.

    In any event, checking for LLD, in my opiinion, is one of the most important exams/evaluations I do as a practitioner (it's where I start actually); and I wish more folks in ALL of the disciplines (especially orthopedics and chiropractics) would pay more attention to LLD's!

    Oh yes, I failed to mention that we also have the Radiogogy Department take an upright scoliosis view at the time of the scanogram study. A repeat upright scoliosis view with an appropriate amount of elevation/lift beneath the heel on the short side will often show immediate reversal of a pelvic tilt and/or amounts of any scoliosis that might be due to the LLD. Sometimes, what looks like a LLD, clinically, is actually primary scoliosis causing a functional LLD - so the upright scoliosis view is also helpful in these regards.

    There may be nothing new to you here, but thought I'd share my ideas on LLD for those who haven't paid that much attention to this entity in the past! ;)
    Last edited by a moderator: Aug 19, 2005
  2. John Spina

    John Spina Active Member


    You are so correct! I havepts with LLD and I find thatLLD can cause A LOT oforthopedic problems.A heel lift usually helps.Checking for gait problems is a good idea. :D
  3. EdYip

    EdYip Active Member

    Great overview, DrLCT2.

    It's also worth mentioning that we be careful when relating LLD's to overpronation: In structural LLD's, it's common to see the longer limb overpronate more to shorten itself. However we must also be able to determine when a unilaterally overpronated foot induces a functional LLD.

    (The same also applies to differing degrees of tibial varum or genu varum/valgum from right side to left).

    I'm probably stating the obvious here, but DrLCT2 is right about how many clinicians overlook it.
  4. Ian Linane

    Ian Linane Well-Known Member

    Michaud in his book talks about assymetric overpronation and its affects upon the lumbar spine. Correct me if I have remembered this wrong but he suggested that the result of the above was that L5 rotates towards the functionally shorter leg and that the rest of the spine flexes towards the apparent longer leg.

    Interesting that DrLCT2 starts assessment at the pelvic level. How about others? I have for a number of years begun at the head rather than the feet.

  5. Craig Payne

    Craig Payne Moderator

    Our research has clearly shown that the longer limb does not pronate any more fequently than the shorter limb in those with a structural LLD - --- its another one of those podiatric myths.
  6. Sammy

    Sammy Active Member

    Hi guys, It's a bit late and Californias finest product has flowed copiously, so please excuse me if I've missed something. Re LLD, a Sacro-Iliac lesion (movement by 'notches') will cause a secondary shortening/lengthening of about 6mm per notch, depending on direction of rotation. This is a generalisation of course, but it is so apparent and has such a huge influence on loads of stuff, and, best of all, it is usually relatively quickand easy to correct and then we have a level playing field for anything else we do to work on. Hic, Sammy
  7. Ian Linane

    Ian Linane Well-Known Member

    Hi Craig

    Thanks for that. Could you clarify if there is (or not) a lumbar alteration in those people who present with one foot more markedly inrolling at the MTJ than the other.

    Thanks Ian
    (wishing I was in California by the sounds of Sammy)
  8. Craig Payne

    Craig Payne Moderator

    Just to clarify ..... asymmetrical foot pronation has the potential to create a LLD of up to 1cm (based on Bill Sanner's work), so obviously this will have consequences further up the chain (esp as the pronation is also associated with internal limb rotation).

    What I am talking about is a foot pronately excessively as a compensation for a STRUCTURAL LLD - something that has crept into podiatric folklore over the years.... but its just another one of those myths :rolleyes: (...'religious fanaticisim' also comes to mind, but more on that later).

    I certainly do not see it clinically - I see feet pronate more on the long leg and I see feet pronate more on the short leg --- I just was not seeing the foot pronating with any increased frequency in the longer leg as I was taught and as I read frequently in the podiatric literature (...funny it does not appear in the orthopaedic or physiotherapy literature :confused: ). Invariably, when I did see a more pronated foot on the longer limb, its was often easy to find another reason for it (eg asymmetrical ankle joint ROM).

    I used to get tired of students coming up to me in clinic when doing a gait analysis and saying things like "Craig, the left leg is longer, but I can't see it pronating more :rolleyes: .... "maybe because it wasn't!!!" --- but thats what they got taught and read in the podiatric literature (they don't any more)

    We did 3 studies:
    1. Measured RCSP and navicular height between the short and long limb in those with a structural LLD --> there were no differences
    2. A subsequent study used the FPI --> no differences
    3. A Pedar in-shoe comparison --> there were some functional differences between the long and short limbs, but they were not related to any asymmetries in foot pronation.

    As part of this, I also did an extensive literature review and it was not surprising that there was never any evidence to support this myth in the first place!!!!! :( (it is an interesting case study all this!!!!) ---- in fact the opposite was the case when viewing the literature!! (I will have to add the exact refs later when in office to get them).

    The first was a study published quite some time ago that looked at 3D rearfoot kinematics and found no difference between the short and long limb in those with a structural LLD.

    The other study is good case of .....(I better not say it :rolleyes: ) --- it was published in JAPMA a long time ago, but the abstract, discussion and stated conclusion of this research was clear - that the foot does pronate more on the long side in those with a structural LLD .... BUT, BUT, BUT and very very very big BUT.... the paper looked at both functional and structural LLD and if you go thru the various tables in the publication (fortunately the paper listed the info on each subject) and extract just the data on those with a structural LLD (the tables mixed them all up) and then do a paired t-test (or wilcoxon) on the data, they actually showed the opposite!!! - ie there was no more pronated foot in the long or short limbs despite their claims ---> points to huge hole in peer review process prior to publication!!!

    It just does not figure that the myth continues, when ALL the evidence says it does not happen.

    We did try and publish our research, but you should have seen the reviewers comments from the journal --- they found nothing wrong with our methods and analysis etc, but spit a whole lot of vitriole with a recommendation to the editor that it not be published - the review was a two page rant paraphrased as "how dare they proove something wrong that every podiatrist knows is right".... they kept refering to all the evidence that supports the concept etc etc, but never mentioned what or where this evidence is. ..... I still have the manuscript (and the reviewers comments), but just have not yet bothered to rewrite it in a format for another journal yet.

    The other amusing thing is, that a couple of years or so ago this topic came up in Barry Block's PM News (Kevin Kirby might remember this), so I posted a message re our research and the lack of evidence etc etc --- needless to say, it did not go down too well (at least I do remember Kevin supporting my observations) - I even got two private abusive emails saying something like "idiot" "moron" "how dare you" etc etc ---- guess which country and 3 letters after their names that these kinds of responses come from :confused: (I wish I kept them as it would be amusing to post them here now....) ..... 'religious fanaticisim' .....

    ....don't you just love this kind of stuff ?
    Last edited by a moderator: Aug 20, 2005
  9. Craig Payne

    Craig Payne Moderator

    BTW, forgot to mention that the most common compensation for a structural LLD is the knee just stays flexed for longer ...
  10. Ian Linane

    Ian Linane Well-Known Member

    Hi Craig

    Thanks for the clarification. My own observations match yours on structural LLD and I was confused for a long time as to why the literature and reality did not seem to marry up. Equally I have felt that something of Michauds comments could readily apply to assymentric MTJ inroll - which I find to be quite common though not always in a marked state.
    Certainly the "what is normal thread" has thrown up some gems.
  11. admin

    admin Administrator Staff Member

    That may point to a greater internal rotation of the lower limb on the side with greater MTJ "inroll" and the proximal effects of that rather than any relation to LLD ???
  12. EdYip

    EdYip Active Member

    Craig, this is all very enlightening and interesting. I always took it as gospel as this was what we were taught.

    One question regarding your LLD studies: How did you establish/determine/measure the presence or absence of a structural LLD? How many mm of difference needed to exist before calling it a structural LLD?
  13. Craig Payne

    Craig Payne Moderator

    We did not have any set mm of LLD for inclusion due to the measurement reliability issues. We used 2 clinician (I was one) who screened a whole group of people using whole range of tests (many of which are mentioned in the first message of this thead) - the criteria for inclusion was an "obvious" structural LLD after other causes ruled out. Both clinicians seperately checked participants and they were only included in studies if both agreed it was an "obvious structural LLD" --- if they did not agree, they were not included - the most likely reason for the disagreement was that the LLD was possibly very small or did not really exist.

    In a perfect world we would have used x-rays but there are ethical issues with using x-ray's (radiation) for research projects.
  14. There is no correlation to limb length differences and amount of foot pronation in what I have seen in biomechanical examination of over 10,000 individuals in the last 20+ years of practice. As Craig clearly states, the supposed association of the "long limb causing pronation" is just another one of those pieces of podiatric folklore that is passed from one instructor to a student then to another podiatrist/student until it becomes "common knowledge". I commonly see feet that are more pronated on the short side and individuals with no LLD that have asymmetrical foot pronation.

    Craig, I do remember this series of postings to PM News on the myth of association of LLD and foot pronation a few years ago and remember that you and I were the only ones to state that an association didn't exist. What else is new, Craig?? Maybe this is somewhat like trying to make the change from the laughable term "first ray hypermobility" to a scientifically definable term "decreased first ray dorsiflexion stiffness"...it is very painful for many podiatrists who are currently "comfortable" with their version of reality to change their "belief system".
  15. efuller

    efuller MVP

    I remember posting to this one two. The rationale for the foot pronating more on the long side was that it hits the ground harder. I asked for the study and then pointed out that the shorter one should hit the ground harder, because it falls farther. :) There are many other factors that go into contact forces.

  16. Thanks, Eric, for refreshing my memory on your contribution to this discussion on limb length discrepancy. During that discussion I stated that I didn't know any mechanical factor that would tend to make the foot pronate more on the long side. The explanation used by most podiatrists is that the individual will pronate more on the long side to get the pelvis level. However, I don't think that most individuals that have unequal leg length know that their pelvis isn't level. And I know of no subconscious mechanism that would make individuals try to keep their pelvis perfectly horizontal during gait. Therefore, there doesn't seem to be either a mechanical reason or a neurological reason for why the long side should pronate more than the short side. This makes sense to me considering I have found no compelling evidence of long side-more pronation or short side-less pronation in the thousands of patients I have examined.

    It is more likely that increased metatarsus adductus deformity in one foot than another will have more influence in reducing STJ pronation than having a short limb.
  17. Craig Payne

    Craig Payne Moderator

    Welcome aboard Simon -yes we have "been there done that" on the podiatry jiscmail list as well (sorry, I should have mentioned those discussions above - at least the response wasn't hostile like from PM News readers in private emails), yet the myth continues.
  18. Craig,

    Strikes me that you ought to get round to publishing that data to begin dispelling the myth. It was 2001 when we talked about it on the jiscmail podiatry mailbase.

    Perhaps the podiatry reviewers are more ready for hearing the truth now.
  19. Craig Payne

    Craig Payne Moderator

    This thread has motivated me to do it... will try again - when back from these two conferences over the next few weeks, will give it priority.

  20. Simon:

    Good to see you join in our discussions. Things seem somewhat slow on the JISC side of the ocean, maybe it'll pick up.

    BTW, is that picture by your name from your days in the punk rock band??
  21. Kevin,

    This is my alter ego- Dave Angel Eco Warrior.

    I wouldn't say things are slow at the JISCMAIL Server, more that we have already discussed many of these self same topics previously on that forum and there is only so many times you can beat the same people with the same bat. What disappoints me though is that after viewing some of the discussion threads here it seems that there really is little that is new under the sun or in podiatry. Nice to see the perennial "what is normal debate" is still going strong :rolleyes: . But that's cool if that's your bag. ;)

    Best wishes,
  22. Simon:

    You are right. It's like reading the newer issues of Runner's World versus the issues from the mid-70s, they are still talking about the best running shoes, how to get faster and how to avoid injuries. ;)

    Anyway...the JISCMAIL list has certainly had its share of very interesting topics over the years but, as you said, we have beat many topics up pretty well on that list. Here at Podiatry Arena there seem to be more people involved with more topics, but still many of the same discussions as we have had over the years on JISCMAIL.

    Maybe we need to get one of the "STJ neutral disciples" to attempt to give me a good definition for STJ neutral in order to get the sparks flying again on one of these lists. That was one of my favorite debates from years ago on the JISCMAIL list. :D
  23. Stanley

    Stanley Well-Known Member


    I have been measuring leg length for over 20 years. I published a method for measuring leg length back in 1985 (J Am Podiatr Med Assoc 1985 75: 349-354.)
    I agree that either foot may pronate more with a leg length discrepancy. I remember that Dr. Subotnik used to lecture that the short leg pronates more, and Dr. Schuster used to lecture that the long leg pronates more. This bothered me as a student back in 1975, so I tried to figure out why these both well respected podiatrists would say the opposite. What I found out was that Schuster's patients were mostly weekend athletes, and Subotnik treated more collegiate, and world class runners. The faster runners would compensate for their short leg by lengthening the short leg, which would eventually cause pronation. The slower runners would shorten the long leg (pronation, knee flexion, internal rotation of the femur, hip drop, etc.). This is not 100%, but more often than not, it correlates.
  24. casanach

    casanach Welcome New Poster


    Surely the long leg will pronate to the end of its range of motion to compensate. This "may" not have happened if both legs were the same length. I only raise the issue because my observation is that in some patients ++LLD = greater pronation at the sub-talr joint and therefor by my logic, the premise stands scrutiny.

    Best Wishes,

  25. Stanley

    Stanley Well-Known Member

    Measuring Leg length

    I think I may not have made my self clear. I gave the reason why the study does not show that the long leg pronates (because there are times that the short leg pronates). This does not mean that a long leg does not cause pronation or does not need to be treated (by raising the opposite side) to stop pronation. Also this does not mean that the equinus on the short side does not cause pronation or does not need to be treated to stop pronation.
  26. Craig Payne

    Craig Payne Moderator

    The point I made earlier - is that this is not the case. All the evidence is that this does not happen. No evidence supports it. The only study that claims to support it analysed the data wrong and actually showed the opposite (see above)
  27. Stanley

    Stanley Well-Known Member

    Leg length Difference


    As a result of the research you mentioned, how will this affect your treatment? :confused:
    Will you now disregard leg length? Will you now prevent pronation of the short side?
  28. Craig Payne

    Craig Payne Moderator

    I NEVER said LLD was not important. All I said is that our research and that of every other researcher that has published data on it has shown that foot pronation is NOT a compensation on the long leg for a structural leg length difference. (A lot of people have written in the podiatric literature that it does, but they presented no data to support the claim)
    I will prevent pronatiopn on any leg if it a contributor to the patients problem.
  29. Stanley

    Stanley Well-Known Member


    Thanks for the reply.

    What is your criterial for correcting for a short leg.

    If foot pronation is NOT a compensation on the long leg for a structural leg length difference, and you will prevent pronation on any leg if it a contributor to the patients problem, then why even look at leg length? :confused:
  30. admin

    admin Administrator Staff Member

  31. Craig Payne

    Craig Payne Moderator

    Stanley....sorry I missed this:

    If its structural and is contributing to the presenting complaint (always debatable), then its a heel raise, generally half the measured size of difference in leg length (bearing in mind the measurement reliability issues) - the raise is either in-shoe, 'out-shoe' or on the orthotic heel post. (Functional LLD is different and can be due to anywhere from the foot to the SI joint to the spine and is treated very differently)

    If the pronation is contributing to the presenting complaint, then its treated, regardless of the leg length. LLD is important, so its always checked for and treated when indicated.
  32. Stanley

    Stanley Well-Known Member


    I am getting closer to understand what you are doing.

    If a leg length is caused by pronation, you correct the pronation.
    If there is pronation and a structural leg length, you correct the pronation.
    As far as treating the leg length you treat it if it is contributing to the chief complaint.
    How do you know if it is contributing to the chief complaint? :confused:

    Do you stand the patient in the orthotic to see what it does to the leg length?

    Do you ever see an unleveling of the pelvis when you stand the patient in the orthotic?
    Last edited by a moderator: Sep 25, 2005
  33. Craig Payne

    Craig Payne Moderator

    Thats the challenge - its a judgement call in each case.
    Not usually - but do eyeball how level ASIC is with foot in NCSP and RCSP (so that is sort of doing the same thing as with an orthotic) and with layers of 3mm polyprop under foot of short leg
    Yes, esp when excessive pronation is asymmetrical . ...thats when I start to worry as what is going to happen further up the kinetic chain, as the body is remarkable at adaptation that we can be "undoing"

    I am on the conservative side when it comes to treating LLD as will only treat if its contributing.

    There is a lot that is going on functionally with the hip/SI joint/pelvis region that I am not begining to understand - clinically leave that to others.

    What I struggle with is trying to come to some sort of coherent understanding of the more proximal effects of LLD and foot function (and the opposite) - the closest I have got is the book by Wolfgang Schamberger on The Malalignment Syndrome: Biomechanical and Clinical Implications for Medicine and Sports ...
    Last edited by a moderator: Sep 25, 2005
  34. Stanley

    Stanley Well-Known Member


    Thanks for the quick reply.

    Do you ever see an unleveling of the pelvis when you stand the patient in the orthotic?
    Yes, esp when excessive pronation is asymmetrical . ...thats when I start to worry as what is going to happen further up the kinetic chain, as the body is remarkable at adaptation that we can be "undoing"
    In the cases that there is an unleveling with the orthotics, wouldn't it make sense to use a heel lift to undo the unleveling that you cause

    There is a lot that is going on functionally with the hip/SI joint/pelvis region that I am not begining to understand - clinically leave that to others.
    May I suggest that you also evaluate the PSIS in neutral and relalxed calcaneal stance position.

    What I struggle with is trying to come to some sort of coherent understanding of the more proximal effects of LLD and foot function (and the opposite)
    I taught this in the early 1980's. If you are interested, I can reduce the 2 hour lecture into a spread sheet.To simplify everything, a joint movement can either lengthen a leg or shorten a leg. Every compensation has an associated overuse injury.
  35. Ian Linane

    Ian Linane Well-Known Member

    Hi Craig / Stanley.

    I am certainly interested in seeing the spread sheet if possible.

    I commonly see what appears to be a LLD in RSCP caused, in my opinion, by an assymetric increased MTJ inroll. My view is to see view them walking RCSP and then see them walking in Orthoses later. When walking RCSP I can see a greater upper body oscilation because the MTJ:

    a. remains unlocked

    and later

    b. allows for an innapropriate momentary increase of internal rotation of the low limb between heel lift and push off

    Admittedly the orthosis will have only a moderate amount of affect in addressing this
    but I have found that intrisinc forefoot balance devices with vertical heels can significantly reduce increased oscillation. Often I am satisfied with this even if there may be some apparent LLD left over. Occassionaly I may apply 1.5mm of cork to the required leg to see if the pt feel this to be more beneficial.

    Can't give research for it but have found the approach to be beneficial.


    The measure for me is whether the pt feels to have and acknowleges:

    a more stable feel in their gait
    a more smoother action in the gait
    a difference in sound in their heel strike in gait
  36. Stanley

    Stanley Well-Known Member

    Hi Ian,

    I'd be more than happy to send you the spread sheet, just need your E-mail address. :) I would've uploaded it, but .xls files are invalid for uploading :( .

    Regarding the patient you are talking about. In this case you have a leg length secondary to pronation. Stop the pronation and you eliminate the leg length. :)
    The key is to figure out why the foot pronates. Is it due to a frontal plane deformity (varus) or is it due to a sagittal plane deformity (equinus)? I imagine a transverse plane deformity can also cause it, but it is not high on my list.
    This is in distinction to pronation as a compensation for a long leg. This would be pronation secondary to a leg length, which is not been shown in the literature to exist. The question is whether this doesn't correlate, or whether the studies can prove whether it does exist. :eek: In other words, there are multiple possible compensations for a leg length, so how can you design a study to show the one factor is signiicantly significant. In fact one of the compensations can result in pronation of a short leg to lengthen a short leg. :confused:
    I know this sounds impossible, but we see it. In some athletes, you will see the a short leg that develops an equinus compensation. The equinus will cause the athlete to both toe out and pronate more. The should cause more unleveling of the pelvis because pronation lowers the arch. In some cases you will find a severe pelvic assymetry and in some cases you won't. The reason that sometimes you won't see the unleveling is an anterior innominate rotation of the iliosacral joint when the femur internally rotates which lengthens the leg. If you do not evaluate the PSIS in neutral and relaxed calcaneal stance position, you would miss this relationship.
    So how would you design a study to show one of these multiple possible relationships are significant? I guess you would have to evaluate the subjects beforehand to see if pronation is causing the shortage, and then you could show the relationship, but it can be said that you haven't proven anything. :eek:
  37. Ian Linane

    Ian Linane Well-Known Member

    Hi Stanley

    I've pm'd you the address.

  38. Craig

    Was looking at this thread Re the three studies which showed no link between the longer leg and the more pronated foot.

    Were they published? If so, would you be kind enough to post the references please? I'd like to read them.
  39. Craig Payne

    Craig Payne Moderator

    Our publication got such a...hole comments from the reviewer I have not got motivated to resubmit for publication after all these yrs. One of the comments from the reviewer was "How dare the authors prove something wrong that we all know is right". They did not want it published!

    The other two publications that show it were: Bloedel & Hauger (1995) and Walsh et al (2000 - they used 3D kinematic to clearly show that there was no more calc eversion in the long leg than the short leg (I will have to look up the full references later as do not have them handy)

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