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.

Normal and Abnormal Talo-Tibial Kinematics and Kinetics

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Kevin Kirby, Jun 30, 2013.

  1. Members do not see these Ads. Sign Up.
    I thought it would be best to move this discussion between Simon, Eric and I to a more appropriately titled thread.

  2. Now we are getting into the good stuff.:D:drinks

    The "ball and socket" ankle seems to occur not so much if a talo-navicular joint is fused later in life, in adulthood. Rather, the "ball and socket" ankle seems to occur in adults who have a congenital talo-navicular coalition and then later develop that "ball and socket" ankle during their youth which then is often first seen and diagnosed in adulthood. In adulthood, if the talo-navicular joint is fused, then a more likely scenario is not a "ball and socket" ankle but rather the more likely scenario is a gradual development of ankle arthrosis most likely due to abnormally high compression forces on the articular cartilage and subchondral bone within the ankle mortise. The difference between childhood and adulthood in this "plasticity" of bones and is the most likely explanation of why a talo-navicular fusion at first walking creates a much different morphological and pathological scenario for the adjacent joints than it does for a talo-navicular fusion in adulthood.

    For a 30 mm wide superior talar dome (probably very close to what an average woman's foot would possess), a talar tilt at one of the talar dome edges would be as follows:

    1 mm = 1.9 degrees
    2 mm = 3.8 degrees
    3 mm = 5.7 degrees
    4 mm = 7.6 degrees

    Therefore, one can see that since the ankle mortice is relatively small, there does not need to be that much separation of the talus from the tibia at one of the superior talar dome edges to get fairly substantial talar eversion/inversion relative to the tibia. In addition, I would imagine that there may be considerable transient compression of the joint cartilage at high joint loads that may allow for a physiologic range of at least 1 mm of joint compression at the talar joint edge which would equate to an extra 1.9 degrees of extra talar inversion/eversion in a talar dome of this width.

    These factors may also help explain the findings from the research from Nester and Arndt.

    Great discusson, Simon and Eric!:drinks
  3. Eric:

    I agree. There is likely some frontal plane rocking of the talus relative to the tibia during normal weightbearing activities in all feet. The question is how much and what is the range of interindividual variation. I would image that in some individuals with more joint compliance, 10 degrees of frontal plane rocking may occur between the talus and tibia during walking/running whereas, in individuals with more stiff ankles, only 1-2 degrees of frontal plane rocking occurs between the talus and tibia during walking/running.

    Certainly, however, Simon's point that this can be a significant amount seems even more likely to me, especially after I crunched the numbers on how little frontal plane talar gapping at the edge of the ankle mortise is required to produce significant frontal plane motion of the talus on the tibia. The superior surface of the talar dome is quite narrow so even 2-3 mm of gapping of the medial or lateral edge of the superior talar dome away from the inferior tibia will cause 4-6 degrees of frontal plane rearfoot motion relative to the tibia.

    In other words, we must reasonably account for "joint slop" in our descriptions of foot and lower extremity biomechanics in order to produce more accurate models of the kinetics and kinematics of the foot and lower extremity during weightbearing activities.
  4. We appear to be on the same page now, Prof. Kirby. :drinks
  5. efuller

    efuller MVP

    I wouldn't be so hasty in saying that there is some rocking in all feet. To create a 1mm gap on either side of the joint there would have to be significant frontal plane moment when the foot is fully weight bearing. If there was no moment then the center of pressure from the tibia applied to the talus would have to be directly in line from the center of pressure from ground reaction force from the bottom of the foot. I'm still trying to wrap my head around that to make sure that it's correct. Another issue is that if there was separation of one side of the joint then all the force going through the joint would be concentrated at a single point or line along the joint surface. If that happened a lot of the time there should be a whole lot more ankle arthritis. It's not the number of degrees, or mm of gapping, its the moments involved in maintaining the gapping in the pressence of compressive forces.

    Another consideration is timing of the motion. During swing, gravity, and or muscle action could create an eccentric load that would cause rocking, but when ground reaction force and the weight of the body become involved this would tend to close any gapping on either side of the joint. It's fine to say that there is rocking, but we still need to be able to explain how that gapping occurs. There is an alternative to the gapping explanation of the data and that is the frontal plane motion is occuring because the instant centers of rotation are not perfectly aligned with the cardinal body planes.


  6. This is interesting http://www.health.uottawa.ca/biomech/csb/Conference Proceedings/NACOB/Abstracts/25.pdf they looked at in-vivo joint contact at the tibiotalar articulation in a "normal" and "flat foot", then looked at the flat foot with an orthotic in-situ. I've copied the image from the paper below. There is clearly a difference in the distribution of loading on the medial and lateral aspect of the the talus in the flat foot, with greater load on the lateral aspect, but this might just be inter-subject variation and have nothing to do with the flat-foot, but it does fit with the observations of other workers regarding contact pattern induced by flat-foot. What's interesting is the within subject change with the foot orthosis in-situ.

    See also: http://www.ncbi.nlm.nih.gov/pubmed/16115417

    And: http://www.ncbi.nlm.nih.gov/pubmed/22608168

    Attached Files:

  7. I think one must consider that the talus could rotate probably at least 1-2 degrees within the frontal plane relative to the tibia and have no gapping of the joint cartilage between the superior aspect of the talar dome and the inferior tibial plafond simply due to transient deformation of the joint cartilage of the talo-tibial joint. That is one of the important functions of the hyaline cartilage of our lower extremity joints: to allow more even distribution of intra-articular compression forces when the joint is subjected to the compression and rotational forces of everyday weightbearing activities.
  8. Yep. This study estimated the cartilage at the tibiotalar articulation (talus + tibia) was about 3mm thick and a peak strain of about 35%

    Anyone have access to a full-text?

    Given that all the studies that have looked at contact characteristics between the talus and tibia report a non-uniform distribution, I should imagine that localised strain within the cartilage may account for some of the frontal plane "rocking".
  9. From my estimate, that would mean that the talus could move in the frontal plane about 1.5- 2 degrees relative to the tibia without any "gapping" at the medial and/or lateral edges of the talo-tibial joint. That's why it's nice to have thicker hyaline cartilage in weightbearing joints: thicker cartilage increases the ability of the bones of a joint to translate and rotate relative to each other while still maintaining joint congruity.
  10. efuller

    efuller MVP

    Ok, I"m starting to buy the argument. However, it's not just position, it is load. Does live cartilage have the ability to deform that much within time frame of a step?

  11. That was an in-vivo study.
  12. Petcu Daniel

    Petcu Daniel Active Member

    The first question that arises in my mind is : comparing with a functional foot orthosis, how much supplementary control ["help" may be a better word !] will offer an action in the frontal plane at the level of ankle joint through an high top boots ? Or which is the efficiency of a sandal having incorporated an FFO compared with a high top boots in influencing the kinematics & kinetics in STJ and ankle joints ?
  13. Daniel:

    The higher and stiffer the boot upper is, the better it can "control" abnormal frontal plane rearfoot motions. In a foot that experiences a large range of medial ankle translation (e.g. posterior tibial tendon dysfunction), then a high, stiff upper boot can probably significantly increase the subtalar joint (STJ) supination moment. However, in a foot with a STJ which is more normally located and has decreased range of motion, then the high, stiff upper boot will provide very little extra STJ supination moment since the ankle simply is not moving much within the frontal plane during gait.

    However, since a boot is not form-fit to the plantar arch of the foot, as is a custom orthosis, the boot will have little mechanical effect on the midtarsal joints and midfoot joints. A sandal with an orthosis and therefore little medial-lateral support to the foot, can still offer significant changes in moments at the midtarsal joint, midfoot joints, some changes in STJ moments and significant changes in plantar pressures versus a sandal without a custom fit orthosis.

    I often find it is best to separate out the functions shoe construction variables from the functions of the foot orthosis in order to try and understand how changes in either the shoe or foot orthosis can help a patient. This does not mean that one should not consider how the combination of a foot orthosis and a shoe may work mechanically together for a patient, but I find it is helpful to separate functions of the shoe and orthosis at times when I am troubleshooting foot orthosis and shoe therapy issues.

    Hope this helps.:drinks

Share This Page