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Jacks Test and failure of STJ supination with ext tibia rotation

Discussion in 'Biomechanics, Sports and Foot orthoses' started by pkt_diamonds, May 27, 2008.

  1. pkt_diamonds

    pkt_diamonds Member

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    I am a podiatry student and have a few questions re: a 10 y.o male patient I had.

    He visited the clinic with his mother because she had noticed that lately he was walking flat footed and seemed a little more uncoordinated than othe kids in his sporting teams. He also seemed to tire more after activity than others although the child himself hadn't noticed this.

    Measurements showed his Rfoot was pronated beyond normal values (RCSP= 8ev in the left and 2ev in the right) but my tutor thought the excessive pronation was coming from else where.

    She performed a Jacks test (Hubscher maneuver) and found his arch height did not increase in either foot.
    She also placed her hands on the childs hips and roted him to the right and then left while he kept his feet planted on the ground. She instructed me to check his MLA while she did this. The arch barely increased in height.
    My tutor seemed to expect this and told me that the pronation was coming from post tib. and tib ant. insufficiency.

    *** Is there anyone who can explain to me the mechanics of how these tests helped her come to this diagnosis?? ***

    - Is it becasue by externally rotating the femur (and hence tibia) this should engage tib ant and post tib to pull the put up off the ground and into supination?

    - Also, does peroneus longus play a part in any of this? Perhaps this may be overpowering tib ant.??

    Thanks for any help!
  2. Donna

    Donna Active Member

    Hi there,

    I've never seen the test that your tutor did with rotating the hips, so I don't know what it's all about, someone else might be able to enlighten you there...

    A very valuable test that you might like to try with this patient next time you see him is the "Supination Resistance Test"... have a search thru Podiatry Arena, there's heaps of info on this test here, and also have a look at Kevin Kirby's "Thought Experiments" (also here on Podiatry Arena) to help you to visualise how the STJ axis functions and how STJ axis location can influence function of the posterior tibialis muscle... :cool: I use this test to help determine what type of treatment each patient requires, including the density of material used to manufacture the orthotic and the level of medial skive required to help control foot motion...


    Donna ;)
  3. pkt_diamonds

    pkt_diamonds Member

    Thanks for the reply Donna,

    Haha, I have just been reading the thought experiments which I see you were involved in!
    Yes, I know of the supination resistance test and performed this the last time I saw the patient. He was difficult to pick up off the ground indicating a laterally deviated STJ axis. I understand that the force that Tib post must now exert in order to sup. the foot is greater.

    ***What I guess I am struggling with is: Would externally rotating the tibia "engage" the post tib and tib ant muscles? Or does roatation of the tiba simply transfer supinatory force and thus motion into the STJ via the bony structure of the joint? Is it a combination of both?

    Im also unsure about the use of Jacks test here. Does this simply show that the Windlass mech. is not functioning correctly??

    She explained this to me right at the end of clinic when we were rushed and thus I didnt get the chance to ask further questions.
  4. markjohconley

    markjohconley Well-Known Member

    typo? should be 'medially'
  5. pkt_diamonds

    pkt_diamonds Member

    Yes... pardon me. Medially deviated. :wacko:
  6. markjohconley

    markjohconley Well-Known Member

    Easy, even Prof. Kirby has "typo"ed.
    Oh, if only this forum was up when I was a student. I highly recommend you keep accessing it, some gems of threads / posts / posters ( biomechanically: Payne, Kirby, Spooner, .... )
    All the best, mark c
  7. Donna

    Donna Active Member

    Hi there Diamonds,

    Again, I'm not sure exactly how this test works, as it's one I have never seen before... Perhaps it has something to do with the weight shifting more laterally and possibly making it mechanically "easier" for the post tib to function. I don't know if it would be lateral rotation causing this though, as we generally see the tibia become less laterally rotated when we use an orthotic to supinate the STJ into a more neutral alignment...

    Do you recall what the test was called, perhaps someone else is familiar with this test and can shed some light?


    Donna :eek:
  8. efuller

    efuller MVP

    The hip rotation test was described in Normal and Abnormal function of the foot by Root, Orien, and Weed. I can't remember if it was in vol 1 or vol2. When you observe people doing this you can see the muscles of the lower leg contract, so I don't think that it is a pure mechanical twist of the femur and then the tibia and fibula then twisting the talus. You have to remember when you do these tests there is a brain attached to the foot and transverse plane twist of the knee is not that comfortable. So, the patient will contract their muscles to decrease stress on the knee.

    The same thing can be seen with Jack's test. When you lift the hallux up and let go it will stay up in the air with the EHL tendon visible. You didn't ask them to help you, but they do.

    Although there are some cadaver studies that fix the foot to the "ground" and twist the foot to cause supination. So, a supination or pronatoin moment can come from above. However, in a living person I would bet that most often it comes from muscle activity.

    For the mechanics of Jack's test see.

    Fuller, E.A. The Windlass Mechanism Of The Foot: A Mechanical Model To Explain Pathology J Am Podiatr Med Assoc 2000 Jan; 90(1) p 35-46

    For sources of pronation see:

    Fuller, E.A. Center of pressure and its theoretical relationship to foot pathology.
    J Am Podiatr Med Assoc. 1999 Jun;89(6):278-91.

  9. LuckyLisfranc

    LuckyLisfranc Well-Known Member

    Please tell me you and your tutor have assessed this child for tarsal coalition...?

    Your final comment on peroneal strength should alert you to this, particularly in a 10yo boy.

    Weight-bearing angle and base of gait views (AP,Lat,MO + Harris/Beath 35/40/45deg).

    Rigid flatfoot in a young person is a coalition until proven otherwise.

  10. Bruce Williams

    Bruce Williams Well-Known Member


    had to LOL when i read your post as I thought exactly the same thing!

    great job!

  11. pkt_diamonds

    pkt_diamonds Member

    Thanks for your advice although I don’t think your condescending tone is necessary.

    I did consider a tarsal coalition but thought it unlikely given the pt. had full ROM at the STJ: 24:10 and 23:9
    He also had excessive motion at the MTJ.

    Does this along with the fact that no pain is being experienced and jno history of ankle sprains not make a tarsal coalition unlikely? (yes I realise that coalitions are often not symptomatic in terms of pain).
    Also there was no tenderness on palpation of peroneus long. tendon / muscle.

    I will be sure to discuss the possibility of a coalition with my tutor.

  12. Two Shoes

    Two Shoes Member


    Is it possible you could provide a pdf link of your 2 papers for wider use.

    I notice Kevin Kirby has provided copies of his papers, and others, in the past and it has been very good. Would you consider doing the same because I would like to read them.

  13. admin

    admin Administrator Staff Member

    Its not that easy. There are copyright considerations and authors do not that own copyright (the journal does). We have gone pretty close here on a number of occasions to breaching the principles and the laws by providing what we do.
  14. Two Shoes

    Two Shoes Member

    It's a shame, but I understand. Thanks, Admin.

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