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HAV pathomechanics

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Nikki10, Apr 17, 2010.

  1. Nikki10

    Nikki10 Active Member


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    Dear all,

    I am preparing for my final Podiatry exams and am struggling with applying pathomechanics to HAV deformity,in terms of how gait may be altered and the effect of HAV on 1st MTPJ.

    Would appreciate any suggestions on good resources or clarification.

    Thank you
     
  2. Griff

    Griff Moderator

    Nikki,

    Here's a few to start you off

    IG
     

    Attached Files:

  3. efuller

    efuller MVP

    Nikki?,

    Are you asking what effects gait has on HAV or are you asking what effects HAV has on gait? Are you asking about what causes HAV? (There are many theories.)

    Eric
     
  4. efuller

    efuller MVP

    Maybe you should skip
    Hallux Valgus and the First Metatarsal
    Arch Segment: A Theoretical
    Biomechanical Perspective Physical Therapy Volume 90 Number 1 January 2010

    I would recommend
    Snijder CJ, Snijder JG, Philippens MM. Biomechanics
    of hallux valgus and spread
    foot. Foot Ankle. 1986;7:26 –39.
    Sanders AP, Snijders CJ, van Linge B. Medial
    deviation of the first metatarsal head
    as a result of flexion forces in hallux valgus.
    Foot Ankle. 1992;13:515–522.


    Some quotes from the paper that you should skip.
    and then a contradiction


    The part about "likened to a pin about which a hinge rotates" is grossly misleading. A joint axis is an imaginary line that describes the motion that has occurred and is not a fixed part of the anatomy of the joint. Think about the metatarsal phalangeal joint. Its "published" axis is one that allows dorsiflexion and plantar flexion. Now grab a hallux and try abduction and adduction. You have just created an axis of motion that is vertical which is impossible if you subscribe to the "pin of hinge" characterization.

    Further quotes
    (sites 28 and 29 are the Snijders papers sited above)

    In the very next paragraph
    Etiology

    They site the cochrane database
    http://www.ncbi.nlm.nih.gov/pubmed/14973960
    Which makes no mention about etiology whether known or unknown in its abstract. There may be some quotes in a full article, but can you really make a quote that something is unknown. After reading those two papers you can make a pretty good case that internal moments at the 1st MPJ are what causes HAV.


    The rest of the article continues around the premise that bones must move about their joint axes. As my example above shows, you can create an infinite number of joint axes for many joints.
    Collapse, or pronation of the STJ, will also tend to evert the foot and this will tend to increase load on the medial forefoot. This will increase the internal moments which is a much better explanation than the one proposed in the paper.

    Nikki,
    I hope your examiners aren't adherents of the "joint axis" theory of bunion development. Hopefully, you will be able to cite literature to back up your case.

    By the way I wrote a paper that theoretically extended Snijder's work to include the Windlass mechanism as part of the cause of HAV. The windlass mechanism of the foot. A mechanical model to explain pathology.

    Fuller EA.

    J Am Podiatr Med Assoc. 2000 Jan;90(1):35-46.

    Regards,

    Eric
     
    Last edited: Apr 18, 2010
  5. Nikki10

    Nikki10 Active Member

    Dear Eric,

    Thank you very much for all the useful information and in-depth explanation.
    To answer your previous question,for the purpose of the exam the main area of focus is the impact HAV may have on gait and the 1st ray biomechanics but I think the papers that you have suggested will hopefully cover this.
     
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