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Effect by custom-made foot orthoses with added support under the first metatarsophalangeal joint

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Petcu Daniel, Jul 15, 2021.

  1. Petcu Daniel

    Petcu Daniel Well-Known Member


    Members do not see these Ads. Sign Up.
    This doesn't seem to be logical to me!

    Effect by custom-made foot orthoses with added support under the first metatarso-phalangeal joint in hallux limitus patients: Improving on first metatarso-phalangeal joint extension

    Abstract
    Background:
    Hallux limitus is one of the most common disorders affecting foot biomechanics. Custom-made foot orthoses can improve the function of the first metatarso-phalangeal joint.
    Objectives:
    The objective underlying this study was to test whether custom-made foot orthoses increased the range of mobility of metatarso-phalangeal joint in patients with hallux limitus.
    Study design:
    Randomized, double-blinded, and clinical trial.
    Methods:
    The study consisted of 20 participants (40 feet) diagnosed with hallux limitus. A control group and an experimental group both wore the same custom-made foot orthoses and, in the experimental group, a support element under the first metatarso-phalangeal joint was added to the orthoses. Two measurements were made with both groups: the relaxed position of the first metatarso-phalangeal joint and the maximum extension of the hallux. These measurements were made before first placing the foot orthoses and 6 months after application of the treatment.
    Results:
    In the experimental group, the results showed an improvement of 4.5° in the relaxed position and 22.2° in the maximum extension being statistically significant (p < 0.001) for both measurements.
    Conclusion:
    Custom-made foot orthoses with added support under the first metatarso-phalangeal joint were proved to be an effective treatment to restore functionality of this joint in hallux limitus patients.
    Clinical relevance
    Limitation of hallux movement in the joints propulsive phase of gait negatively affects the biomechanics of the lower extremity, causing changes in the rest of the joins. The use of foot orthoses designed in this study restores range of motion of the first metatarso-phalangeal joint.
     
  2. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    In 2001 I obtained a US Patent incorporating a proprioceptive signal under the 1st metatarsal and hallux.

    What you call a hallux limitus is a misnomer for a genetic foot type - the Primus Metatarsus Supinatus foot structure.

    Nice to see my research being investigated.
     
  3. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Hallux Limitus is a condition in which the 1st metatarsal phalangeal articulation is inflamed, stiff and sore. It is a symptom that occurs when this articulation functions around a position outside its’ anatomical neutral position. The further the 1st metatarsal phalangeal articulation functions outside its anatomical neutral position (defined as joint congruity) the greater are the chances of developing a Hallux Limitus.

    In the Primus Metatarsus Supinatus foot structure or the PreClinical Clubfoot Deformity, the 1st metatarsal phalangeal articulation is forced to function significantly outside its anatomical neutral position, hence it is a fairly common symptom in either of these two genetic foot abnormalities.

    By placing a wedge underneath the 1st MPJ, you are repositioning this joint towards its' anatomical neutral position (ANP). Hence, the expected outcome would be exactly what was reported in the double blind study authored by Gordillo-Fernandez, Benhamu, Salomon et al. (increased ROM in the 1st MPJ when using the wedge underneath the joint)

    Axiomatically:
    • The closer a weight bearing joint functions around its' ANP, the greater its' range of motion (which was reported in the above paper) and less chance of inflammation from overuse.
    • The further a weight bearing joint functions from its' ANP, the less its' range of motion and greater chance of inflammation from overuse.
    Just food for thought.

    ANP defined as joint congruity
     
  4. scotfoot

    scotfoot Well-Known Member

    "By placing a wedge underneath the 1st MPJ, you are repositioning this joint towards its' anatomical neutral position (ANP). Hence, the expected outcome would be exactly what was reported in the double blind study authored by Gordillo-Fernandez, Benhamu, Salomon et al. (increased ROM in the 1st MPJ when using the wedge underneath the joint)"

    So primarily a mechanical intervention not "proprioceptive" ?
     
  5. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    The dimension of the wedge (underneath the 1st MPJ) determines how it acts, mechanically or proprioceptively. In general, as the dimension of the wedge increases, the propensity, to act as a mechanical support, also increases. But there are other considerations at work here.

    Among them are:
    • The severity of the supinatus (greater in the PreClinical Clubfoot Deformity)
    • Materials used in the wedge
    • Geometric slope angle of the wedge
    • Patient's sensitivity to the wedge (this varies substantially). For example the simplistic statement that a 2mm wedge underneath the 1st MPJ will act as a proprioceptive signal in all patients is not true. In some patients it may act as a proprioceptive signal, in other patients it may function as a mechanical support. This is determined in the assessment of the patient.
    Axiomatically, lower dimensioned wedges edge toward a proprioceptive signal, higher dimensioned wedges edge toward a mechanical support.

    This is not to be confused with the shift in the functional position of the 1st MPJ. A minimal signal underneath the 1st MPJ can result in an exponential shift in the functional position of the joint (this is another variable from patient to patient). And conversely, an aggressive wedge underneath the 1st MPJ may result in a lateral slippage off the orthotic, acting as an irritant and not as a mechanical support (again, another variable from patient to patient).

    The considerations are replete enough to fuel a thread just on this point alone. Maybe someone would like to initiate such a discussion.
     
  6. scotfoot

    scotfoot Well-Known Member

    "Axiomatically, lower dimensioned wedges edge toward a proprioceptive signal, higher dimensioned wedges edge toward a mechanical support."

    A proprioceptive signal sent from exactly where ? What tissue ?
     
  7. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    The theory in Posturology is that the proproprioceptive signal is generated by the activation of the Meissner corpuscles (partially capsulated, coil-like structures) superficially located within the dermal papillae of glabrous skin (plantar surface of the feet).

    The afferent terminals of these mechanoreceptors contain stretch sensitive ion channels that open when the membrane is deformed (e.g., when pressure is placed on the afferent terminal). This leads to membrane depolarization and the generation of an action potentials that travels to the CNS (specifically to the cerebellum).

    You can read more about this by downloading the chapter in my book - Chapter 5, Foot to Brain Connection.

    Still a lot to understand.
     
  8. scotfoot

    scotfoot Well-Known Member

    Meissner corpuscles register light touch .
    Not proprioceptive sense .
     
  9. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Correct, Meissner corpuscles register light touch. And it is the light touch that activates the proprioceptive signal. Read the chapter, it will help explain the theory.

    I used the term proprioceptive to indicate:
    1. A stimuli (light touch stimuli) that is produced and perceived regarding the position and movement of the body
    2. How the patient reacts to that light touch varies from patient to patient. Some patients are insensitive to the light touch and consequently the 2mm wedge acts as a mechanical support. Other patients are very sensitive to light touch, and in those patients the 2mm wedge will act as a proprioceptive signal.
     
  10. scotfoot

    scotfoot Well-Known Member

    I have no idea if your insoles work or not but I can say ,given your explaination , that you are using the term proprioceptive incorrectly.
     
  11. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    You might be correct, but I disagree.
    Regarding my insoles, or any other insoles used in Posturology, that would be another thread.
     
  12. efuller

    efuller MVP

    Was the measurement non weight bearing? Did they do a repeatability study on the measurements? Was there no change in the control group? How was the measurement done?

    There is quite a different result from the Roukis, Sheerer paper that placed things under the first met head when standing.
     
  13. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Where can this paper be downloaded
     
  14. efuller

    efuller MVP

    Hallux limitus is a condition where the first MPJ can't get very far from its neutral position. Brian are you confusing joint axis with neutral position? Your comment above does not make any sense.

    A joint axis is an imaginary line. An imaginary line cannot limit motion. Tension in the platnar fascia and compression at the MP joint surface can limit motion. Those compressive forces can get quite high and those forces can cause pain, stiffness and swelling and cartilage erosion at the joint.
     
  15. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    I am not confusing neutral position with joint axis, which is an imaginary line that projects through the pivot/rotation point in a joint. That is another discussion, and not what I am discussing.

    Basically I am suggesting a reason for the limitation of range of motion (e.g., dorsiflexion) in the 1st MPJ during open chain. And you are right, compression of the MPJ can result in limitation of motion. And that is exactly what occurs when an articulation is forced to function around a position outside of its' joint congruity (I use both terms interchangeably. There is disagreement doing so, again another thread of discussion)

    Many papers have been published on the limitation of ROM seen in HL. (I have cited some publications below just to clarify that we are discussing the same topic). Many publications refer to HL as a diagnosis. I disagree, I see HL as a symptom not a primary pathology.

    Functional hallux limitus is defined as a functional inability of the proximal phalanx of theI hallux to extend on the first metatarsal head during gait
    Durrant B, Chockalingam N.
    J Am Podiatr Med Assoc. 2009 May-Jun;99(3):236-43. doi: 10.7547/0980236.
    PMID: 1944817
    Functional hallux limitus (FHL) refers to dorsiflexion hallux mobility limitation when the first metatarsal head is under loading conditions but not in the unloaded state
    Reliability Study of Diagnostic Tests for Functional Hallux Limitus.

    Sánchez-Gómez R, Becerro-de-Bengoa-Vallejo R, Losa-Iglesias ME, Calvo-Lobo C, Navarro-Flores E, Palomo-López P, Romero-Morales C, López-López D.
    Foot Ankle Int. 2020 Apr;41(4):457-462. doi: 10.1177/1071100719901116. Epub 2020 Jan 29.
    Functional hallux limitus or rigidus caused by a tenodesis effect at the retrotalar pulley: description of the functional stretch test and the simple hoover cord maneuver that releases this tenodesis.
    Vallotton J, Echeverri S, Dobbelaere-Nicolas V.
    J Am Podiatr Med Assoc. 2010 May-Jun;100(3):220-9. doi: 10.7547/1000220.
    PMID: 20479455
    Restriction of greater toe dorsiflexion without degeneration of the first metatarsophalangeal joint is defined as hallux limitus.
    The Role of Plantar Fascia Tightness in Hallux Limitus: A Biomechanical Analysis.
    Viehöfer AF, Vich M, Wirth SH, Espinosa N, Camenzind RS.
    J Foot Ankle Surg. 2019 May;58(3):465-469. doi: 10.1053/j.jfas.2018.09.019. Epub 2019 Feb 7.
    PMID: 30738612​
     
  16. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    To expand a little more on my proposed pathomechanics seen in HL:
    • Both Primus Metatarsus Supinatus and PreClinical Clubfoot Deformity force the medial column of the foot (which is structurally in supinatus) to roll inward and downward (pronated) in a open kinetic chain (e.g., weight bearing).
    • This automatically places the 1st MPJ in a more or less (depending on the severity of the PMS or RFS) dorsiflexed position.
    • Some or all of the dorsiflexion available to the 1st MPJ in a open kinetic chain is then taken up (reduced) by this repositioning of the medial column of the foot.
    This can easily be demonstrated:

    In close kinetic chain, force the foot into extended pronation (this can be done by rotating the hips). Note what happens to the ROM within the 1st MPJ, compared to the ROM in an open kinetic chain: The ROM is reduced.

    Interesting enough, one of the most common symptoms seen in either the PMS or PCFD is HL.
     
  17. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Your comment resonated to a point that I have spent the last few days rethinking my views on this subject.

    You made a valid point, I was wrong.

    I am shifting the foot's pattern of stimulation (proprioceptive signal to the cerebellum) by placing wedges underneath the feet. So strickly speaking, that is a mechanical device.
    • Succinctly, I am using a mechanical device to adjust the proprioceptive signal to the cerebellum
    Thank you for that epiphany.
     
  18. efuller

    efuller MVP

    Brian, are you confusing joints? Are you talking about the MPJ metatarsal phalangeal joint, or are you talking about the first ray; metatarsal cuneiform and navicular cuneiform joints. I don't see how "roll inward and downward" causes dorsiflexion of the MPJ.


    We agree that with STJ pronation you will tend to see a decrease in MPJ dorsiflexion. Where we are disagreeing is on the explanation of the mechanism. Your explanation is not clear in that you have said it has something to do with joint congruity. Which doesn't make any sense because the MPJ is congruent in the position it is in when it is in stance.

    What I am saying is that with STJ pronation the distance from the first met head to the calcaneal insertion of the plantar fascia increases and this increases the tension in the fascia which increases compression of the mpj and limits the dorsiflexion of the MPJ regardless of the foot type.
     
  19. Brian A. Rothbart

    Brian A. Rothbart Well-Known Member

    Can you expand on that?
     
  20. efuller

    efuller MVP

    Expand on which part?
     
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