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Menopause? muscle changes? Effect on biomechanics?

Discussion in 'General Issues and Discussion Forum' started by kerstin, Jan 17, 2008.

  1. kerstin

    kerstin Active Member


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    I am torturing my brain by the question what the menopause do or better what the hormones are doing in that stage of life on muscles and if there are biomechanical changes??
    Notting to do with me but I can better be prepared ;-)

    best regards,
    Kerstin
     
  2. kerstin

    kerstin Active Member

    hey nobody who has experience or has a clou?? Or is it just a stupid thought that it would have an effect on muscles and on the biomechanics?? I just have some women patients who have developed an extreme MTJ collaps (coalition navicular/calcaneal, so rigid) around the age of 45 or older. So I just thought it had something to do with there menopause. I don't know. I don't know if there are others who have seen that fenomen?

    regards,
    Kerstin
     
  3. Admin2

    Admin2 Administrator Staff Member

  4. Craig Payne

    Craig Payne Moderator

    That may be due to bone remodelling from the osteoporosis that generally starts setting in around then.
     
  5. Kerstin:

    My thoughts are that the elastic modulus of the ligaments of the post-menopausal woman are reduced when compared to their pre-menopausal state. This would certainly make sense from a mechanical standpoint, especially considering the high percentage of patients with posterior tibial dysfunction being post-menopausal women. However, to this date, I don't know of any research that has studied the mechanical properties of the plantar ligaments of pre- and post-menopausal women. I do remember from years back a study that measured the mechanical properties of the iliotibial band and found that it had a decreased elastic modulus in older women than in younger women. But I haven't seen it for years and don't have a reference for it. I wouldn't think that the changes in bone density would have enough effect on foot mechanics to cause the increased flattening of the medial longitudinal arch seen in post-menopausal women, but I could be wrong on that one.

    Excellent research project for a smart Belgian female podiatrist, if you ask me!:rolleyes:
     
  6. jos

    jos Active Member

    No experience with muscle tone, but a couple of patients of mine insist that their hyperidrosis/bromidrosis started with menopause................??
     
  7. kerstin

    kerstin Active Member

    Thanks, I am sure that the tibialis posterior is a main factor in the developing proces but why it gives a solid region around navicular/talus/calcaneal? there is no reconstruction possible and there is lots of force in that region too.
    Yes, a research on that topic would be nice, so I know a very good clinical researcher who lives in sacramento and listens to the name Kevin, so I challenging you ;-)).

    Best regards,
    Kerstin
     

  8. It would not take much change in the elastic modulus of the plantar ligaments in a woman with a medially deviated subtalar joint (STJ) axis to start the cascade of events that cause posterior tibial dysfunction after menopause.

    First of all, a reduction in elastic modulus in all the ligaments of the foot would tend to cause increased STJ pronation moment since the medial longitudinal arch has 50% more plantar ligaments than does the lateral longitudinal arch. This increase in number of ligaments means that any increase in elongation of the plantar ligaments for a given force being applied will cause more flattening in the height of the medial arch than it will cause a flattening in the height of the lateral arch which, in effect, produces an increase in forefoot varus (or a decrease in forefoot valgus) deformity.

    Secondly, with the dorsiflexion of the medial metatarsal rays relative to the lateral metatarsal rays, there will be increased ground reaction force (GRF) on the lateral metatarsal heads which will increase the STJ pronation moment which will, in turn, cause increased STJ pronation motion and increased internal rotation, plantarflexion and medial translation of the STJ axis relative to the plantar foot (Kirby KA: Subtalar joint axis location and rotational equilibrium theory of foot function. JAPMA, 91:465-488, 2001.) This medial deviation of the STJ axis will not only shorten the supination moment arm for the posterior tibial tendon but will also lengthen the pronation moment arm for GRF, both of which will cause a demand for the posterior tibial tendon to have increased tensile force within it in order to produce the same supination effect on the foot when compared the tensile force required within the tendon when the STJ axis is less medially deviated (Kirby KA: Conservative treatment of posterior tibial dysfunction. Podiatry Management, 19:73-82, 2000.)

    The more internally rotated STJ axis will have its greatest effects on increasing the magnitudes of STJ pronation moment during the late midstance phase of gait when the GRF has moved towards the forefoot and the moment arms for GRF to cause STJ pronation moments become larger. Late midstance is also the time of gait when the dorsiflexion moments on the medial metatarsal rays are the greatest which will also tend to progressively cause more medial metatarsal ray dorsiflexion during late midstance over time, especially if the STJ axis deviates further medially and the posterior tibial muscle/tendon complex and spring ligament complex becomes weaker and/or becomes plastically elongated.

    Therefore, theoretically, in a woman that already possesses a medially deviated STJ axis in her pre-menopausal years, the following cascade of events may occur, simply due to the initiating event of a reduction in elastic modulus of all her plantar ligaments after menopause:

    1. Increased elongation of plantar ligaments of medial longitudinal arch.

    2. Increased dorsiflexion of medial metatarsal rays, increased STJ pronation moment and increased STJ pronation motion.

    3. Increased medial deviation of STJ axis.

    4. Decreased supination moment arm for posterior tibial tendon and increased pronation moment arm for GRF in late midstance phase of gait.

    5. Increase tensile stress on posterior tibial tendon and spring ligament complex.

    6. Plastic elongation/tearing of posterior tibial tendon and/or spring ligament complex.

    7. Processes #1-7 continue until some source for STJ supination moment prevents further STJ pronation motion and stops the deformation of the foot architecture.
     
  9. kerstin

    kerstin Active Member

    So we can only prevent further deformation by giving supination moment?
    Is there someone who knows if there are hormons who gives muscle weakness?? Are is it just an age thing? that the abilty to retain tendon loading decrease with age.

    best regards,
    Kerstin
     
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