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.

Foot type and plantar pressures

Discussion in 'Biomechanics, Sports and Foot orthoses' started by NewsBot, Mar 14, 2008.

  1. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1

    Members do not see these Ads. Sign Up.
    The effect of foot type on in-shoe plantar pressure during walking and running.
    Chuckpaiwong B, Nunley JA, Mall NA, Queen RM.
    Gait Posture. 2008 Mar 10 [Epub ahead of print]
     
  2. DaVinci

    DaVinci Well-Known Member

    Why do journal editors let authors get away with such statements. All this study was about was plantar pressures and NOT stress fractures. Surely before such a statement can be made if its known that this foot type increases the risk for stress fractures. Since when did plantar pressures have any link to stress fracture risk? Am I missing something here?
     
  3. Admin2

    Admin2 Administrator Staff Member

    Foot pronation protective for stress fractures
     
  4. It is ground reaction force (GRF) plantar to the metatarsal heads that causes metatarsal stress fractures. Without any GRF or plantar pressure under the metatarsal heads, then no metatarsal stress fracture would occur. Therefore, I don't think that the author's statement, "Therefore, individuals with a flat foot could be at a lower risk for lateral column metatarsal stress fractures, indicating that foot type should be assessed when determining an individual's risk for metatarsal stress fractures.", is incorrect. However, if I was reviewing this paper, I would have had the authors move this statement on stress fractures from the abstract to the discussion of the paper.
     
  5. DaVinci

    DaVinci Well-Known Member

    The point I was trying to make is that there NO data that has linked high GRF or plantar pressures to stress fractures.

    Beno Nigg made this assertion very strongly at a conference here in Australia last year and I was surprised to find that there was no evidence for the link (I think most of the audience was also surprised). I did some digging around after the conference and he was right. I could find nothing.

    From what I can read of the above study is that they justified the study under the pretence of screening for a stress fracture risk factor, when the risk factor they are screening for has not been established as being a risk factor.
     
  6. I agree with Benno. Do you really need to have a published scientific study to have good confidence in stating that increased force/pressure on the metatarsal head will lead to increase risk of stress fracture in the metatarsal? Biomechanical modelling will prove this to be a fact. In fact, biomechanical modelling will also predict that the stress fracture will most commonly occur at that area of the metatarsal where there is the least area moment of inertia, i.e. at the metatarsal neck.

    Would you need to also have a published scientific study to believe that hitting someone on top of the foot with a hammer may result in a metatarsal fracture? I'll bet there haven't been any papers published on hammer-induced fractures to the forefoot just as there have been no papers published on metatarsal head plantar pressure causing stress fracture. Why, because it is common sense mechanics.

    Stress fractures don't occur in a nonweighbearing situation, they occur in situations with weightbearing forces (i.e. pressures) acting on the metatarsal head that are either increased in magnitude or increased in frequency. Have you ever seen a metatarsal stress fracture in someone that was non-weightbearing? Non-weightbearing means zero plantar pressure at the metatarsal head.

    Let me put it into different terms. Under which circumstances would you expect a wooden beam to more likely develop a crack or failure: one where there is greater bending loads or one where there is lesser bending loads?
     
  7. Mart

    Mart Well-Known Member

    Just wanted to add a bit of detail to this thread, it reiterates and lends support to Kevins comments and looks at a parallel issue.

    I am trying to improve my interpretive reasoning of in shoe and pressure mat data currently and reading around the subject with reference to gaining a deeper understanding of the tissue material characteristics, the mechanical responses of our anatomy to stress during stance and gait and how the measurements we can take can be informative or misleading.

    One thing I have noticed using in shoe pressure measurement (ISPM) for evaluating foot orthoses design for DM related metatarsal head overload is that effective reduction of ground reaction force by foot orthoses does not necessarily eliminate damage to associated skin which commonly is attributed compression stress.

    I am curious to know if others have noticed this. For example I did ISPM study last week on a patient with loss of protective sensation, and prior history of neuropathic ulceration. The comparative IPSM data showed a reduction of ground reaction force at the lesion site from 2X normal values unprotected to zero in terms of peak pressures and force/time integrals with foot orthoses use. In terms of design goals the foot orthoses worked perfectly however using these foot orthoses with appropriate foot-wear he develops significant keratoma and pre-ulcerative changes which to date are only managed with debridement at two weeks interval.

    A couple of extracts from studies below explore possible explanations for this and the link between ISPM values and bone stress/strain using finite element modeling which seems to give us best available picture currently.



    1 FROM

    Three-dimensional finite element analysis of the foot during standing--a material sensitivity study.
    Source:
    Journal of Biomechanics [0021-9290] Cheung yr:2005 vol:38 iss:5 pg:1045 -54


    Knowledge on the effect of soft tissue compliance or
    other structural characteristics on the stress distribution
    of the plantar foot surface and bony structures is
    essential to achieve an appropriate individualised treatment
    strategy such as an orthotic design.

    The pressure distributions between the foot and
    different supports were measured experimentally with
    the use of in-shoe pressure sensors and pedobarograph
    (Cavanagh et al., 1987; Lavery et al., 1997; Patil et al.,
    2002; Raspovic et al., 2000; Lord and Hosein, 2000;
    Lord et al., 1986). Due to the difficulties and lack of
    better technology for the experimental measurement, the
    load transfer mechanism and internal stress states within
    the soft tissues and the bony structures were not well
    addressed.

    In order to supplement these experiments, researchers
    have turned to computational methods. The finite
    element (FE) analysis has been an adjunct to experimental
    approach to predict the load distribution
    between the foot and different supports, which offer
    additional information such as the internal stresses/
    strains of the ankle–foot complex.

    A number of foot models have been developed based on certain assumptions
    such as simplified geometry, limited relative joint
    movement, ignorance of certain ligamentous structures
    and simplified material properties (Chen et al., 2001;
    Gefen, 2000; Gefen, 2003; Jacob and Patil, 1999;
    Kitagawa et al., 2000; Nakamura et al., 1981). The
    models developed by Jacob and Patil (1999) and Gefen
    (2003) have been employed to investigate the biomechanical
    effects of soft tissue stiffeningin the diabetic feet.

    Their models predicted that the peak plantar pressure
    was found to increase with soft tissue stiffness but with
    minimal effect on the bony structures. Gefen (2003)
    further speculated that the development of diabeticfoot-
    related infection and injury was more likely
    initiated by micro-damage of tissue from intensified
    stress in the deeper subcutaneous layers rather than the
    skin surface.

    It has been shown in the literature that FE models can
    contribute in familiarizing the effects of thickness and
    stiffness of plantar soft tissue on plantar pressure
    distribution (Gefen, 2003; Jacob and Patil, 1999;
    Lemmon et al., 1997). A detailed model of the human
    foot and ankle, incorporating realist ic geometrical
    properties of both bony and soft tissue components is
    needed to provide a more realistic representation of the
    foot and the supporting condition s, in order to enhance
    the understandingof the ankle–foot biomechanics
    (Camacho et al., 2002; Kirby, 2001).

    For the sake of convergence of solution and
    Minimizing computational efforts, most of the linearly
    elastic FE foot models reported so far (Chen et al., 2001;
    Chu et al., 1995; Jacob and Patil, 1999) assigned
    relatively stiff mechanical properties for soft tissue,
    where the Young’s moduli were selected as being 1MPa
    or larger. These values of Young’s moduli are much
    larger than those obtained from in vivo experimental
    measurements of plantar soft tissue, ranging from 0.05
    to 0.3MPa under strains of 10–35% (Gefen et al.,
    2001b; Zhenget al., 2000). For FE models usinga
    nonlinear material model for plantar soft tissue (Gefen
    et al., 2000; Gefen, 2003; Nakamura et al., 1981;
    Lemmon et al., 1997), the adopted stress–strain behaviour
    varied as a result of the intrinsic variation of
    individual tissue, measurement techniques and environment.
    The stress–strain response of plantar soft tissue
    was often obtained from either indentation or compression
    test of in vivo or cadaveric specimens (Gefen et al.,
    2001a; Klaesner et al., 2002; Lemmon et al., 1997;
    Nakamura et al., 1981; Miller-Younget al., 2002).

    In the literature, there is still a lack of material sensitivity study
    to quantify the effects of soft tissue stiffening on plantar
    pressure distribution usinga geometrical accurate threedimensional
    (3D) foot model.

    The objective of this study was to develop a
    comprehensive FE model of the foot and ankle, using
    3D actual geometry of both skeletal and soft tissues
    components and to investigate the effect of soft tissue
    stiffness on the plantar pressure distributions and the
    internal load transfer between bony structures.

    2 FROM

    Surg Radiol Anat. 2007 Oct;29(7):561-7. Epub 2007 Jul 10
    Clinical significance of musculoskeletal finite element model of the second and the fifth foot ray with metatarsal cavities and calcaneal sinus.

    Because of high incidence among runners and military personnel,
    plantar fasciitis and metatarsal stress fractures are
    commonly assumed to be caused by repetitive microtrauma
    of the corresponding tissues [1, 16]. The results in microtrauma
    are associated with not only the conditions of
    stresses and strains of plantar longitudinal arch [20, 21], but
    also the distributions of plantar pressures. While techniques
    for plantar pressure measurements are well developed,
    direct measurement of the internal stress/strain is diYcult
    [4]. In the past three decades, two-dimensional (2D) Wnite
    element (FE) models [6, 13, 15] and 3D FE models [4, 7] of
    the foot have been reported to predict stresses/strains of
    metatarsals and plantar fascia. In these models, homogeneous
    medium for foot bones and nonlinear material characteristics
    for plantar soft tissues were assumed; however,
    the architecture of intrinsic muscles, metatarsal cavities and
    calcaneus sinus have almost not accounted for. Therefore,
    an accurate FE model of plantar arches, incorporating more
    realistic geometrical and material properties of musculoskeletal
    components is needed to enhance realistic understanding
    of podiatric biomechanics of metatarsal stress
    fractures and plantar fasciitis [12, 22].

    The goal of this study was to develop anatomically
    detailed FE models of the second and the Wfth foot ray
    using experimental dataset of Virtual Chinese Human
    (VCH) “female No 1”, which incorporated four bone media
    accounting for metatarsal cavities and calcaneal sinus, as
    well as muscles and ligaments in plantar arch. Then, internal
    stresses/strains of the detailed models were compared
    with that of the simpliWed models without metatarsal cavities
    and calcaneal sinus during standing posture.

    Musculoskeletal FE models of the second and Wfth foot ray
    with metatarsal cavities and calcaneal sinus have capability
    to predict stresses/strains concentration on the shaft and
    basis of metatarsals, bone trabecula around metatarsal cavities,
    and plantar fascia insertion of calcaneus during standing
    posture. Moreover, the predicted tension/compression
    stress Xows are geometrically similar with the tension/compression
    trabecular architectures in sagittal sections of
    metatarsal and calcaneus.

    With more accurate and realistic
    FE predictions, podiatric biomechanics will contribute
    more extensive and valuable insight into metatarsal stress
    fractures and plantar fasciitis.

    Hope this adds something helpful


    Cheers

    Martin


    The St. James Foot Clinic
    1749 Portage Ave.
    Winnipeg
    Manitoba
    R3J 0E6
    Phone [204] 837 FOOT (3668)
    Fax [204] 774 9918
    www.winnipegfootclinic.com
     
    Last edited: Mar 18, 2008
  8. Martin:

    Thanks for those (I especially liked the references in the first article). ;)

    Here is another finite element analysis study that concluded that stress fractures will occur at the narrow portion of the second metatarsal due to bending moments. And bending moments, of course, are due to plantar forces/pressures on the metatarsal head.

     
  9. Here's the PDF of one of the papers that Martin posted. It shows how Finite Element Analysis may be used to determine the internal stresses within the structural components of the human foot.

    Cheung JT, Zhang M, Leung AK, Fan Y: Three-dimensional finite element analysis of the foot during standing--a material sensitivity study. J Biomech, 38:1045 -54, 2005.
     
  10. NewsBot

    NewsBot The Admin that posts the news.

    Articles:
    1
    Differences in plantar loading between flat and normal feet during different athletic tasks.
    Queen RM, Mall NA, Nunley JA, Chuckpaiwong B.
    Gait Posture. 2009 Jan 19. [Epub ahead of print]
     
Loading...

Share This Page