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Pelvic rotation in gaite

Discussion in 'Biomechanics, Sports and Foot orthoses' started by asdf2017, Nov 5, 2017.

  1. asdf2017

    asdf2017 Member


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    Hi, I'm trying to understand the biomechanics of walking. And I have a question.

    Some books say that in the transverse plane the peak internal rotation occurring at foot strike and the maximal external rotation at opposite foot strike. Like this:

    prnt.sc /h6lk84

    Others say: For the initial 15% to 20% of the gait cycle, the pelvis rotates in an internal (counterclock) rotation. Like this:

    prntscr.com /h6lmgv

    Which is correct? Where does the pelvis rotate in Loading Response gait phase, internal or external?

    ps sry cant post normal links
     
  2. asdf2017

    asdf2017 Member

    Omg nobody understands gait biomech?
     
  3. stevewells

    stevewells Active Member

    Hi whatever your name is - are you a student?
    Its complicated to explain just like that but if you can get hold of a copy of Perry's Gait analysis there is a great chapter that explains it. Ib fact, if you are trying to understand the mechanics and pathomechanics of walking its a fantastic resource.
    Hope that helps

    Steve
     
  4. efuller

    efuller MVP


    On the one hand you (nameless one) are bright enough to see a discrepancy in information in textbooks. On the other hand you are inexperienced enough to use counter clockwise in describing this motion. (Which foot, from above, from below) and to say "Omg nobody understands gait biomech?"

    One reason no one answered you might be that the distinction you are asking about is not relevant. Why do you care about this discrepancy? Motion is not as important as the forces that cause the motion. Winter has written many papers looking at gait using inverse dynamics to look at joint power. If you want to understand the biomechanics of gait, you need to understand joint power.

    If you really care about the question, you could look at the citations in the textbook and read the original articles that were used as a source for those statements.
     
  5. asdf2017

    asdf2017 Member

    stevewells,

    I read this book and you are right that this is a good book. But it contains one short chapter about the pelvis. And most graphs depict the movement in the joints in the sagittal plane. As I understand it, Perry describes the rotation of the pelvis in the same way as in the first example "in the transverse plane the peak internal rotation occurring at foot strike and the maximal external rotation at opposite foot strike"
     
  6. asdf2017

    asdf2017 Member

    efuller,

    You also understand, but advise me to read more?:)
    I can not find all the sources freely available. And you are right I'm inexperienced.
     
  7. bobtheweazel

    bobtheweazel Member

    I don't think there's necessarily a discrepancy here. I just wouldn't get bogged down in the exact percentages since those will vary depending on the velocity of gait.

    Let's say, for reference, that pelvic neutral in the transverse plane would be with the long (sideways) axis of the pelvis perpendicular to the forward line of progression, so with no rotation either clockwise or counterclockwise or however you want to say it. The pelvis should reach its maximum rotation away from that neutral position during double limb support.

    So to walk through the cycle:
    Swing Phase - The swing side pelvis starts to rotate forward as the trailing limb lifts off the supporting surface to swing forward and continues to rotate forward throughout swing phase. During this period the stance (contralateral) limb is in midstance and as the swing side pelvis rotates forward using the stance side hip as a pivot point the pelvis will be relatively externally rotating over the stance limb which will passively externally rotate the stance limb—a component of resupination at the foot. During this period the swing limb passes the stance limb so that the swing limb becomes the leading limb.
    Initial Contact and Loading Response - The swing limb becomes the leading stance limb in the first period of double limb support. The pelvis continues rotating the same way throughout this period which can be seen as an external rotation above the now trailing limb (in preswing) and an internal rotation above the leading limb (in initial contact and loading response) which contributes a passive internal rotary force to the leading stance limb—a component of pronation of the foot. This is the first time in the gait cycle that the pelvis reaches its maximum excursion from neutral in the transverse plane. NOTE: This maximal point of rotation of the pelvis coincides with the point in loading response in which the center of mass has reached its lowest vertical level. However significant/insignificant the determinants of gait may be the pelvic rotation determinant is describing this point, which may help you remember this at least.
    Midstance and Terminal Stance - The trailing limb enters swing phase as the pelvis switches its direction of rotation. So the pelvis now rotates forward with the swing limb which is seen as an external rotation above the stance phase limb throughout midstance and terminal stance. This external rotation of the pelvis above the stance limb contributes an external rotary force to to the stance limb which initiates resupination of the foot and contributes to resupination in an ongoing fashion. During this period the contralateral/swing limb has passed the stance limb so that the stance limb is now the trailing limb. NOTE: If you were talking pathomechanics and there is pathology at the foot then external rotation of the pelvis may not be enough to initiate resupination of the foot which could result in more problems along with the abductory twist that Kirby talks about frequently.
    Preswing - This is the second period of double limb support as the leading limb is in initial contact and loading response and the trailing stance limb is in preswing. The rotation of the pelvis continues which can be seen as an external rotation above the preswing/trailing limb and internal rotation above the leading limb—the opposite of what I said in the "initial contact and loading response" section above. This is the second time in the gait cycle that the pelvis reaches its maximum excursion from neutral in the transverse plane.

    If there's a typo or something that doesn't make sense in what I just said let me know. I didn't do any extensive proof-reading here.
     
  8. asdf2017

    asdf2017 Member


    I.e. at Foot Flat.

    Your description completely coincides with how I understand the second of the examples I have written. If it were not for Kinesiology of the Musculoskeletal System - Neumann, I would still consider that the point of maximum rotation of the pelvis occurs when the heel contacts the floor.

    I still do not understand why you and user efuller think this discrepancy is not important, because it changes the "normal gait" pattern.
     
  9. asdf2017

    asdf2017 Member

    bobtheweazel,

    It is sometimes difficult to understand what the authors mean.
    For example, a screenshot from a Neumann's book about which I wrote above:
    [​IMG]

    http://prntscr.com/hay2fi

    This graph does not coincide with that description by the movement of the pelvis about which we speak. But at the same time he writes: For the initial 15% to 20% of the gait cycle, the pelvis rotates in an internal (counterclockwise) rotation.
     
    Last edited: Nov 15, 2017
  10. bobtheweazel

    bobtheweazel Member

    I would say that your first example simply shows a range of values, within which it is likely that some have peak pelvic rotation at initial contact and some have peak rotation some time early in loading response and some have peak rotation some time late in loading response. Some probably even reach peak rotation at initial contact and maintain that same rotation throughout loading response. But we can't see that from that image because it just shows the full range of values but not individual values from individual trials. There could be a few outliers who peak at very high rotations at initial contact that skew the chart to look that way. There could be only one outlier skewing it that way. You really can't tell from that graph. I would add to this that trying to define "normal" based on position alone is tricky business because everybody has a slightly different normal. As long as there's no pathology, then somebody is probably at their normal. Also, I'm not sure what we're talking about would significantly alter gait anyway. I think you would have to convince me of that.

    In the most recent link that you posted, that looks like a graph of hip rotation relative to the line of progression, which is not the same as pelvic rotation. For instance we can say that perhaps the leading limb side of the pelvis is rotated 3 degrees forward at initial contact while the hip is rotated so as to be externally rotated 2 degrees from the line of progression. Then the total angle between the pelvis and hip is 5 degrees but you would say the pelvis is rotated 3 degrees and in this case in your second example you might say that the hip is externally rotated 2 degrees. Think about it this way, if the hip were actually only externally rotated only two degrees at initial contact and we know that the pelvis is internally rotated maybe 3-7 degrees (using numbers from your graphs) then at initial contact the limb would be internally rotated relative to the line of progression and so would contact at the medial heel when we know that what actually happens is the lower limb is slightly externally rotated relative to the line of progression at initial contact which allows the foot to contact just on the lateral side of the heel.
     
  11. asdf2017

    asdf2017 Member

    You mean graph for a particular person might look like RED line:
    https://prnt.sc/haze46

    I assumed that the curve for a particular subject can only have as a blue curve. Furthermore, the author gives a comment: peak internal rotation occurring at foot strike and the maximal external rotation at opposite foot strike.


    I cant understand.
    As I think on the graph the pelvic rotation on the femur is depicted, and by this it is understood that if the pelvis moves ASIS forward on the side of the supporting leg in the LR phase, this is the external rotation of the hip joint of the leg. However, on the graph, we see only the internal rotation from the beginning and up to 50% GC.
     

    Attached Files:

  12. bobtheweazel

    bobtheweazel Member

    When I said the most recent one you posted I was talking about this one. It seems to be for hip rotation rather than pelvic rotation, which are two independent measurements. Screenshot_20171115-180827.png
     
  13. asdf2017

    asdf2017 Member

    Yes I understood, and my last comment was about this.
     
  14. stevewells

    stevewells Active Member

    This is worth a read and has some useful references -
     

    Attached Files:

  15. efuller

    efuller MVP

    What do you use a normal gait pattern for? If someone is walking "abnormally", is it better or worse than normal? Better or worse for what? Limping is abnormal, but it is better for reduced pain. Do we just want to say you are walking abnormally, or do we want to figure out why someone is limping.

    "Tis not knowing much, but knowing what is important." Sorry I've forgotten attribution of that quote. I saw it on a title page of a textbook. I can't say that I remember anything else from that textbook, but that quote is worth a lot.
     
  16. stevewells

    stevewells Active Member

    Sounds like something Mark Twain would say
     
  17. efuller

    efuller MVP

    This is why you should go back to the original sources to see what definitions they are using. Are the original sources looking at pelvis relative to leg motion, or pelvis relative to ground, or.....
     
  18. asdf2017

    asdf2017 Member

    Another discrepancy. Why he calls it external rotation?
     

    Attached Files:

  19. stevewells

    stevewells Active Member

    Why he calls what external rotation?
     
  20. asdf2017

    asdf2017 Member

    pelvic rotation...
     
  21. stevewells

    stevewells Active Member

    From the screenshot you put up he appears to be referring to the stance leg - my assumption (perhaps wrongly?) was that he was referring to external rotation of the stance phase leg - which in itself is a poor description as I would take that as meaning the tibia - he seems to be referring to the femur relative to the pelvis which would be external rotation of the hip. If he means the whole leg then i think he is describing hip rotation.
     
  22. asdf2017

    asdf2017 Member

    quote from Thomas C. Michaud - Foot Orthoses and Other Forms of Conservative Foot Care(1987):
    However, as ground reactive forces beneath the heel begin 10 lessen toward the end of midstance, the subtalar joint begins to supinate as the foot attempts to convert itself from the mobile adaptor necessary during the contact period to the rigid lever necessary for the propulsive period. It partially accomplishes this task by taking advantage of the forward momentum of the contralateral lower extremity: the forward momentum of the swing phase leg externally rotates the pelvis (white arrow in Fig. 2-10), which then externally rotates the weight-bearing leg (black arrow in Fig. 2-10).
     
  23. efuller

    efuller MVP

    This picture clearly illustrates why the notion that the rotation of the swing leg does not cause supinatoin of the subtalar joint, contrary to what the caption of the picture claims. The statement could be true if pelvis was applying a moment to the femur that would cause the femur to externally rotate relative to the foot. The problem with this is that the pelvis can rotate over the top of the femur without applying a moment to the femur. In fact if the person was contracting their muslces to rotate the pelvis (looking from above clockwise rotation of pelvis over right femur) this would tend to cause internal femoral rotation relative to the foot.

    There are joint power studies showing that the supination moment at the STJ does come from above, but the joint power studies can't differentiate the source of that moment. A much more likely culprit is the posterior tibial muscle. This makes sense in that sometimes you see late stance phase pronation and that could be explained by a moment created by the peroneal muscles. Late stance phase pronation exists and this is also contrary to the notion that the swing leg, through the pelivis, causes STJ supination. The pelvis always swings over the stance hip, you don't always see STJ supination.
     
  24. asdf2017

    asdf2017 Member

    quote from Thomas C. Michaud - Foot Orthoses and Other Forms of Conservative Foot Care(1987):
    However, as ground reactive forces beneath the heel begin 10 lessen toward the end of midstance, the subtalar joint begins to supinate as the foot attempts to convert itself from the mobile adaptor necessary during the contact period to the rigid lever necessary for the propulsive period. It partially accomplishes this task by taking advantage of the forward momentum of the contralateral lower extremity: the forward momentum of the swing phase leg externally rotates the pelvis (white arrow in Fig. 2-10), which then externally rotates the weight-bearing leg (black arrow in Fig. 2-10). Since rhe leg and talus behave as a closed kinetic chain during midstance, external rotation of the weight-bearing leg causes the talus to abduct, which in turn supinates the subtalar joint.:)

    efuller, from text of book we see contrary: leg externally rotates the pelvis and which in turn supinates the subtalar joint,
     
  25. efuller

    efuller MVP

    I'm not sure what you are saying. (Which leg?) Are you agreeing with me? Let me know if you want me to explain further why I think the textbook is wrong.
     
  26. asdf2017

    asdf2017 Member

    efuller,
    I want to say that the author of the book does not mean what you are talking about. He gives a description that the momentum of the swing leg causes the pelvis to rotate (for me it is not clear why he calls this the external rotation of the pelvis, if following the terminology this is an internal pelvic rotation) and further supinate STJ. Fig. 2-10 he uses to clarify his point of view, instead of refuting his statement.
     
  27. RobinP

    RobinP Well-Known Member

    asdf2017 - as you can probably see, there is a fundamental issue with the definition of "normal" . I can't speak for Eric, but the description of late stance phase describes what we used to think was a required and "normal" part of the gait cycle. Unfortunately, the time that we spend walking on a flat, non slippy surface in barefoot is probably very limited and therefore, that "normal" gait pattern probably only exists in a fraction of our waking day. The rest of the time, the forces acting upon us (and our feet/hips etc) dictate the motion. So, the validity of that "normal" walking description is debatable from a functional point of view.....unless you are sitting an exam

    Watch the first 20 secs of the video below

    Q: How "normal" is this running pattern?
    A: Normal (for him)
    n=1
     
  28. asdf2017

    asdf2017 Member

    Statistically, "normal" means "average."
    If we take a hundred runners, how many of them will have such pronation?
     
  29. efuller

    efuller MVP

    The author said the swing leg creates external rotation of the stance leg and this causes STJ supination in the stance leg. (First line of caption) That is what I am talking about. And I am saying the author is wrong in making that claim. I stated my reasons for thinking this in post #23. You can use the same diagram to make my point. The author is trying to claim that motions cause motions, when moments (torque) cause rotations.
     
  30. efuller

    efuller MVP

    Unfortunately, you have entered the realm of podiatric normal which has several definitions. One of those definitions is ideal.
     
  31. asdf2017

    asdf2017 Member

    I gave a quote from the text(in post #23) where the author gives a description. The author said:
    1 the forward momentum of the swing phase leg externally rotates the pelvis
    2 the pelvis then externally rotates the weight-bearing leg (black arrow in Fig. 2-10)
    3 the weight-bearing leg in turn supinates the subtalar joint.
     
  32. RobinP

    RobinP Well-Known Member

    No, it doesnt. There is normal distribution which describes a bell curve

    Regarding 100 runners, it doesn't matter how much pronation they have or any other movements. For the purpose of what they are doing, the motion can be considered normal for them. If they remain uninjured, how can we determine that their biomechanics are normal or abnormal?
     
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