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Joint Axis Location and Rotational Equilibrium Theory

Discussion in 'Biomechanics, Sports and Foot orthoses' started by mike weber, Feb 28, 2011.

  1. Members do not see these Ads. Sign Up.
    This started out of a caption competition thread - Here

    We have discussed the midtarsal joint here Midtarsal joint Equilibrium theory here

    and there is a ton of Subtalat joint axis related threads here - http://www.podiatry-arena.com/podiatry-forum/tags/index.php?tag=/subtalar-joint-axis/

    The point to this thread Comes back to this question Why do we focus on the Subtalar joint axis location and rotation Equilibrium .

    Sorry for the cut and paste - I seem to have lost some of my powers.
  2. End of a long day whats STALARE stand for.

    SALRE = Subtalar Joint Axis Location and Rotational Equilibrium
  3. Should have been Sub Talar Joint Axis Location And Rotational Equilibrium Theory Of Foot Function. Which would be STJALARET OFF. Which sounds like the sort of curse I apply to the cat when he jumps on my face when I'm asleep.

    I'd knocked off the OFF. But the point is that the AND is significant. The theory teaches both SAL AND RE. Thus I was crediting the paper in its entirity for the way of thinking which led to that definition of FnHL. As I've been trying to get Ed to understand, SALRE is about more than SAL. Its about RE as well!

    If you go back to Rotational Equilibrium Across the Subtalar Joint Axis (REASJA), the 1989 paper, and look to Figure 1 you will see a Rotational equilibrium diagram for the Talo crural joint. So there.
  4. If the cat jumped on my face it would be called F.O.C , and were Ill leave it before i have to edit myself.

    While great to credit SALRE in changing your thinking, every joint will have it's own rotation and equilibrium theory. I think this is another important issue SALRE is the subtalar joint .MALRE maybe the midtarsal joint etc. While related understanding foot function means more than the subtalar joint.

    So what I Don't get it Robert your discussing FnHL and moments about that joint why not be specific about that joint ?
  5. efuller

    efuller MVP

    There is an interrealationship between the STJ and the MPJ. When the STJ pronates the tension in the plantar fascia increases. Increased tension in the fascia will create a plantar flexion moment at the MPJ. Additionally, in reverese a dorsiflexion moment at the MPJ will increase tension in the plantar fascia and will usually create a supination moment at the STJ. They are interrelated.

  6. Medial STJ axis location>>increased GRF plantar to medial column>>increased tensile force within medial bands of plantar fascia>>increased internal hallux plantarflexion moment>>increased tendency for external hallux dorsiflexion moment from GRF during propulsion to not cause hallux dorsiflexion acceleration during propulsion>>increased tendency of functional hallux limitus.

    Therefore, STJ spatial location and MPJ mechanics are mechanically very closely related to each other.
  7. Eric and Kevin I did say that they are related.

    So to make it clear my point when discussing a joint other than the subtalar joint say Roberts example of dorsiflexion and plantarflexion moments occuring at the 1st mtpj

    Is the theory
    1 axis and rotational equilibrium at the 1st MTP joint


    2 Subtalar Axis and Rotational Equilibrium (SALRE)

    Ofcourse I agree that the mechanics of the subtalar and midtarsal joint effect the 1st MTPJ , what I saying is each joint will have its own axis and rotational equilibrium and we sould be specific about the joint.
  8. Who knew a fraction of a slide could cause so much controversy?

    You are right Mike, it's the 1st mpj I'm looking at. I was merely using SALRE as shorthand for the "fissics approach". Is that so wrong?
  9. Not wrong and I´m not trying to get up your goat. Just saw this as a interesting point.

    And discussing plantarflexion and dorsiflexion moments at the 1st MTP joint using the physics approach is the only way forward.

    If the slide had of said 1st MTPJ (Rotational equilibrium ) is that not more specific ?and get people thinking about moments across all joints ?

    I know someone who like to be specific in their terminology ;)

    PS are you collecting on your beers in April ?:drinks
  10. Touche ;)

    Possibly. Maybe. Depends how quickly I heal. Where are you flying in to?
  11. efuller

    efuller MVP

    Rotational equilibrium at joints is important to look at for examining tissue stress. You examine the joint that is / are relevant to the anatomical structure that you are interested in.

    Remember Ed's straw man argument opposing SALRE. He said it was bad because it didn't look at all joints. SALRE is an important part of examining all joints.

  12. Or Perhaps Mike is coming out in sympathy with Ed...:rolleyes::D;):pigs:
  13. Not a chance.:deadhorse:

    For the record

    1 SALRE is an important concept when looking at all joints of the foot in relation to foot function

    2. Each joint will have it´s own Rotational Equilibrium theory and when discussing a joint in isolation we are looking at the axis and rotation equilibrium of that joint.

    Points 1 and 2 are interrelated where SALRE will effect other joints of the foot and the axial position and rotational equilibrium of other joints in the foot will effect SALRE.
  14. Mike:

    I understand where you are coming from and I totally agree. Each joint of the foot and lower extremity can be better understood by understanding the rotational forces that act across it during normal and abnormal foot function.

    From my perspective, if I can back far enough away from this topic to be objective, what the subtalar joint axis location and rotational equilibrium (SALRE) theory of foot function represents is a basic change in emphasis within podiatric biomechanics from trying to understand foot mechanics from a kinematics aspect and toward a direction of tryingto understand foot mechanics from a kinetics aspect.

    I believe, SALRE represents one of the first departures within the podiatric literature at analyzing the balancing of rotational forces across a joint of the foot in order to explain foot and orthosis function and foot pathology. No longer are we now concerned with heel bisections, forefoot to rearfoot relationship, subtalar neutral position, or position of the calcaneal bisection during relaxed bipedal stance.

    With SALRE we are now trying to simplify the kinetic analysis of a very important joint of the human foot to only analyzing the STJ spatial location, locations of external forces from GRF and locations of internal forces from the tensile forces from muscles and ligaments and the interossous compression forces in the joints of the foot. I believe this is a crucial first step for the international podiatry profession to understand the pathological internal forces that cause the pathologies we see in the human foot, and, as such, is a crucial first step toward evaluating our mechanically-based treatment methods, such as foot orthoses, and toward developing better mechanically-based treatment methods in the future.

    As Michael has suggested, the kinetics of all the other joints of the foot should be evaluated and analyzed as I have done for the subtalar joint in order to understand what makes these joints function in both normal and pathological conditions. This will involve making free-body diagrams, analyzing external and internal forces and discussing rotational equilibrium in both static and quasi-static situations and should include the ankle joints, midtarsal joints, midfoot joints, metatarsophalangeal joints and the digital interphalangeal joints. In addition, the mechanical interrelationships between these joints need to be analyzed from a kinetics aspect in order to better understand how each joint and how each structural component of the foot and lower extremity affects the other.

    This is too much work for me for a lifetime. However, I am pleased to be working with a few of you on tackling these projects for the future of the podiatric profession.:drinks
  15. drsha

    drsha Banned

    My question is why the STJ Axis and Not the 1st MP Joint Axis (1MPJELRE) or another?

    Dr Sha
  16. Franklin

    Franklin Active Member



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