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HAV Aetiology - Current theories

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Sammo, Mar 18, 2009.

  1. Sammo

    Sammo Active Member

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    Hi All,

    I was wondering what is the current theories on aetiology of HAV.

    At uni we were taught that a combination of inappropriate footwear, family Hx, poor biomechanics, e.g short/long first met, primus metatarsus elevatus, excessive pronation, FnHL, angle of gait, foot hypermobility and ankle equinus (increase forefoot loading) were all in part responsible.

    I also remember reading in a text book that increased GRF under the 1st MJP may cause FnHL and therefore either an abducted angle of gait and/or an abductory twitch to allow the foot to toe off through an oblique line through the hallux and 1st MPJ. That the ongoing force applies to the side of the hallux in time causes the abduction in the hallux, retro grade trauma then causes an adducted 1st Met.

    This information is what I recall being taught.. it is not me suggesting that this is the mechanism. Is this mechanism still regarded as a possibilty, or has it been consigned to the theory graveyard??

    Does anyone have any information that would help???

    Kindest Regards,

  2. efuller

    efuller MVP

    To explain bunion formation you have to explain a change in position. It takes a force to change a position. So each of the above should be looked at in terms of its ability to create a force in the correct direction to cause a bunion. A shoe can push from medial to lateral on the hallux to create a bunion. I don't know how family history can cause a bunion. However, certain biomechanical characteristics can be inheirited, but it might be better to focus on those characteristics than on the general category of heredity.

    I have proposed a mechanism that goes a bit farther than McGlamry's reverse buckling concept. 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.

    In that model high forces under the first met head and hallux caise the internal forces that bring about reverse buckling. A longer first metatarsal has been shown to be correlated with increased forces under the first metatarsal.

    A high pronation moment will tend to increase forces in the windlass and increase the forces in reverse buckling. High pronation moment is easier to understand than excessive pronation, because it specifies what aspect of pronation to measure. (pronation can be measured with maximum eversoin speed of pronation, most inverted position to most everted position etc.)

    Foot hypermobility is an undefined term.


  3. Sammo

    Sammo Active Member

    Thank you Eric, I appreciate the reply. I have just downloaded that paper from Japma and will look over it closely.

    Do you think that a patient with ligamentous laxity as verified by the Beighton or brighton criteria would be at risk of greater deformity than someone with a very similar foot type and no hypermobility. Working with the assumption that thier foot may be more easily deformable due to the ligamentous laxity?

    Many thanks,

  4. Here is some more reading, not on the stuff i e mailed you...

    A controlled prospective trial of a foot orthosis in the treatment of juvenile hallux valgus.
    J.Bone Joint Surgery 1994: 76B:210-214

    Showed, alarmingly, that there was a GREATER incidence of HAV in the group treated with orthotics.

    The significance of pes planus in juvenile hallux valgus.
    TE Kilmartin, WA Wallace - Foot Ankle, 1992

    Showed NO CORRELATION between Arch height and HAV in juveniles.

    Relationship between adolescent bunions and flatfeet.
    V Kalen, A Brecher - Foot Ankle, 1988

    Also failed to show a link.

    Hope this is useful.

  5. efuller

    efuller MVP

    Yes. If the deforming force is equal and the resistance to the deforming force is less, I would expect more deformity. I haven't read up on ligamentous laxity recently. Is the collagen different in tensile strength, or more likely to exhibit plastic deformation.


  6. Sam:

    In order to develop an abducted hallux (i.e. more deviated toward 2nd digit) there must be either increased external hallux abduction moment (e.g. medial toe box of shoe pushing on medial hallux), increased internal hallux abduction moment (e.g. tensile force from plantar fascia, flexor hallucis brevis, adductor hallucis, flexor hallucis longus is more lateral to vertical 1st MPJ axis than normal), or a decreased internal hallux adduction moment (e.g. loss of tibial sesamoid, transection of abductor hallucis muscle).

    The physics concept of rotational equilibrium can be easily applied to the vertical axis of the 1st MPJ to model how tension and compression forces acting from external or internal on the hallux and 1st MPJ complex can cause the gradual progression of hallux abducto valgus and eventual bunion deformity. Root et al's "Normal and Abnormal Function of the Foot" goes through the process in more detail than any source that I know, and even though I don't agree with all they say, I think the photos and drawings in the book are the best at describing how hallux abducto valgus and bunion deformity develops over time.

    Hope this helps.
  7. drsarbes

    drsarbes Well-Known Member

    My local news paper had an article last fall and it said tight and or high heeled shoes caused bunions.

    Case solved.
    Now we can move on.

  8. Not strictly true, as both groups had juvenile hallux valgus at the start. What the study showed was that the group treated with modified Root devices deteriorated more than the control group during the study period.
  9. Admin2

    Admin2 Administrator Staff Member

  10. Sammo

    Sammo Active Member

    Hi Eric, Been ploughing through as much literature as I can find but not getting a definitive answer on this question (probably looking in the wrong places, and i am sure someone will correct me on this shortly.. but i'll stick my neck way way out with a hair brained, crazy-as-a-box-of-frogs theory and say...).

    Could it depend on the reason for the hypermobility, whether it is someone at the end of a normal range of distribution, or whether they have a collagen disorder such as Marfan syndrome or ehlers-danlos... (working under the assumption that benign joint hypermobility syndrome and the various collagen disorders are distinct entities and not different ends on a single spectrum).

    With the former perhaps there is a greater degree of plastic deformation, which through time and continued injury begins to lose it's integrity.

    With the latter it depends on how the collagen gene's are wrongly expressed as to whether they exhibit a lower tensile strength or whether the are more plastic?

    Or is this all just: :pigs:

    Kind regards,

    (a slightly cowering) Sam
  11. tarik amir

    tarik amir Active Member

    We have been observing that patients undergoing HAV surgery, who have ligamentous laxity have tended to exhibit no or significantly less osteochondral defects of the 1st met head. Possibly the collagen make-up of these patients resists cartilage breakdown.

    Most of the surgical text I believe would suport the idea that HAV is an inherited condition. Inheriting an unstable foot type.
  12. Chris Kemp

    Chris Kemp Member

    Dear Eric,

    This paper may be of interest:

    Mafart, B. (2007) Hallux Valgus in a Historical French Population: Paleopathological Study of 605 First Metatarsal Bones. Joint Bone Spine. 74(2) pp. 166-170 Edinburgh: Elsevier Ltd.

    Mafart tracked the historical correlation between footwear and HAV, suggesting that in the 17th Century when wearing high heels was a manly pastime, more men than women exhibited HAV. This would lend weight to the hypothesis that footwear is one contributing factor.

    Kind regards,

  13. efuller

    efuller MVP

    Hi Chris,

    Yes I agree that shoes can be a contributing factor. For me the question is why are shoes a contributing factor.

    I don't have the original article, but in Daryl Phillips chapter on HAV in Heatherington's textbook of surgery he sited an article that was pretty convincing to me that showed shoes were a factor. The story was that this a reproductively isolated population where a large percentage of the people did not wear shoes. The incidence of HAV was higher in the shod population, but people who went barefoot did get HAV. So yes, shoes are a factor, but not the only factor.


  14. "Maclennan (1966) studied 1,256 barefooted subjects in New Guinea (665 males, 691 females). The author reports a prevalence of hallux valgus of the order of 1% in males and 4% in females. Clearly, this prevalence is lower than has commonly been reported for shod populations. However, shoes could have played no role in the development of the deformity within this population and cannot, therefore, explain the gender difference in the prevalence of hallux valgus within this population" Spooner S.K.: Predictors of Hallux valgus: a study of heritability. PhD thesis. University of Leicester 1998

    Maclennan, R.: Prevalence of hallux valgus in a neolithic New Guinea population. The Lancet 1966: June: 1398-1400

    See also:
    Meyer, M.: A comparison of hallux abducto valgus in two ancient populations. JAPA 1960; 50:388-389

    Gottshalk et al.: The prevalence of hallux valgus in three South African populations. SA medical journal 1981; 60: 655-656

    From my PhD conclusion:
    "Common to all of the predictors of hallux valgus identified in this study is that they appear to affect the degree of hypermobility within the foot and/ or the direction and magnitude of the forces acting on the foot. These two factors would seem, then, to be the key determinants of whether or not the first metatarsophalangeal joint angle remains within the normal limits or progresses beyond the abnormal threshold to become hallux valgus as clinically defined." Spooner S.K.: Predictors of Hallux valgus: a study of heritability. PhD thesis. University of Leicester 1998

    For a nice biomechanical analysis see:
    Snijders, C.J. et al.: Biomechanics of hallux valgus and spread foot. Foot and Ankle 1986; 7: 26-35
  15. Agreed
  16. Sam,

    Look up: relaxin
  17. Pod on sea

    Pod on sea Active Member

    Orthoses give relief from hallux valgus pain according to this quote from a 2008 Cochrane review ''This review shows that for people younger than 60 years of age with painful hallux valgus (a condition where the base of the big toe bulges out sideways, away from the foot) custom-made foot orthoses:

    Reduce foot pain after 6 months compared to no treatment, but may not reduce foot pain after 6 or 12 months compared to surgery".

    Does anyone know what the longer term outcomes are for orthoses vs no treatment?
    Are there any in-shoe pressure scan studies that show if 1st mtpj/overall foot function is improved in HAV when wearing an orthotic?
    On what do you base the decision to prescribe an orthotic for HAV vs refer for surgery?

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