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Sub 1st MPJ pain - help with diagnosis

Discussion in 'General Issues and Discussion Forum' started by TDC, Oct 15, 2014.

  1. TDC

    TDC Member

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    Hi there,

    I would love some input from the arena brains trust on a case of mine.

    38 year old female in good general health. Relatively sedentary - works an office job sitting most of the day, 4days a week and works retail standing up in flat, hard ballet flat style shoes 2days per week. This has been the work situation for over a year. No previous foot pain or trauma is reported.

    Presenting complaint:
    Sudden and severe onset of sub right 1st MPJ pain 10 days ago - Woke up in the evening with pain and swelling. 3 days prior to seeing me her General Practitioner sent for x-rays and ultrasound (no diagnosis was made as yet). Pt cannot recall any incident of trauma or unaccustomed activity that would cause such pain. Pt asked to point to most focal point of pain - corresponds to lateral sesamoid region.
    Antalgic gait - Pt chooses low gear propulsion to avoid pain.
    Pt has not been taking any pain meds consistently since it happened. No treatment thus far.

    On assessment:
    Pain to palpate anywhere sub Right 1st MPJ -especially lateral sesamoid.
    Pain sub 1st mpj and associated shooting nerve pain into MLA when dorsiflexing hallux. Mild swelling still present. No abnormal plantar HK patterns seen (no HK at all really). Mild forefoot valgus with 1st MPJ in line weth lesser MPJs. Without seeing normal weight baring (WB) foot posture due to pain cannot tell the functional foot posture. However, non-WB pedal joint ROM all seem WNL. Very weak eversion strength and mild weakness of inversion strength on Right vs Left.

    X-ray: I have attached an AP view. No sesamoid axial was taken unfortunately.

    Ultrasound showed irregularity of lateral sesamoid, soft tissue thickening and increased vascularity around the sesamoid indicating a current inflammatory process.

    There is clearly fragmentation of both sesamoids on x-ray with the lateral also very opaque indicating poor bone health/density. I also query the eroded appearance of the lateral aspect of the distal metatarsal head which looks eroded and sclerotic.

    Current diagnosis: Lateral sesamoid stress fracture with possible AVN. I think the medial sesamoid may have a fracture at proximal medial aspect also.

    Anyone see anything tell tail in this image to aid in diagnosis or prognosis? This amount of damage seen on x-ray obviously didn't happen 'overnight'.

    Currently I have her in a rocker sole CAM boot with felt deflective padding to reduce plantar pressure sub 1st MPJ. She has been advised on a course of oral anti-inflammatories, iceing 2x15min daily and a compression sleeve to help settle the acute pain and inflammation also.

    In others experience is this just an atypical presentation of a sesamoid stress fracture or am I missing something? If there is avascular necrosis will this generally change the management plan. I'm considering sending for MRI.

    Any input greatly appreciated.

    Tom do Canto

    Attached Files:

  2. EJRJ

    EJRJ Member

    It is possible a bipartite sesamoid? It´s a other option.
  3. W J Liggins

    W J Liggins Well-Known Member


    Interesting case. From the X-ray I think you are correct. Probably the medial sesamoid is 'just' bi-partite - the edges are smooth and there does not appear to be any reactive soft tissue effect. The lateral sesamoid seems to be fractured and, as you say, there is reactive bone involvement of the metatarsal head consistent with AVN. Some degree of metadductus is demonstrated. The second met. demonstrates cortical thickening suggestive of excessive weight bearing which is frequently noted in feet with dorsiflexion of the 1st ray. Again, the radiograph shows a notable gap between the 1st and 2nd cuneiforms which tends to confirm this.

    I will stand corrected by my 'biomechanical colleagues' but I would guess that prior to the alteration in gait caused by the pain, this patient was pronating excessively (sorry Robert et al.) at the STJ in mid stance and at toe-off, and this is the source of the pathology. I agree that an MRI will be definitive, although there is little other than unloading and anti-inflammatories that will help.

    Please let us know what the MRI shows.

    All the best

    Bill Liggins
  4. Lab Guy

    Lab Guy Well-Known Member

    I concur with Simon. You can see the radiolucent areas within the fractured fibular sesmoid indicating AVN. I am suspicious of the proximal portion of the tibial bipartite sesmoid and would order a Tc bone scan.

    A biomechanical risk would be a foot with a higher metatarsal declination angle (Forefoot equinus) as the passive tension of the plantarfascia would cause an increased posterior force on the first met head (by way of its attachment to base of proximal phalanx) as the moment arm is longer to the base of the first met generating a higher plantarflexory moment of the first met head resulting in increased dorsiflexion stiffness to GRF acting on the plantar sesmoids. This scenario would then create more compression on the plantar sesmoids. A foot with a medially deviated STJ axis would not be at risk due to the low met inclination angle, proving a poor mechanical advantage for the plantar fascia to passively create a plantarflexory moment against the dorsiflexion moment from ground reactive forces. The second metatarsal would bear more GRF as the first metatarsal would dorsiflex. The fibular sesmoid would also be much less likely to be directly under the first metatarsal head.

    I have treated a number of these cases and never had success with conservative treatment. I would make a plantar incision in the first interspace (to avoid a symptomatic weightbearing scar) and excise the fibular sesmoid which was always extremely successful. Orthotics would be made to off-load the tibial sesmoid as it will be accepting increased compressive forces. If it was my foot, I would elect to have it removed ASAP.

  5. TDC

    TDC Member

    Thanks to all for the input and thanks for the link Simon, it was helpful. I'll continue with recommending cam boot offloading then further assess the foot posture and possible biomechanical aetiologies once no longer so antalgic. I have already suggested surgery may be required if conservative measures fail and she is happy with this plan.
    Anyone have experience with adjunct therapy while in the offloading stage to help facilitate increased blood flow to the likely AVN present? I read on an old thread about tibialis posterior nerve block to aid in 'opening up' collateral arteries to the sesamoids...
    Does anyone actually do this? I have never really heard of this been done for this prior to reading about it on here

    Thanks again for the input.

  6. Craig Payne

    Craig Payne Moderator

    gout ?
  7. TDC

    TDC Member

    Hi Craig,

    Do you have any experience or know of any literature to do with gout of the sesamoids?
    It's a good differential considering the odd onset of severe symptoms during the night.
    Unfortunately I didn't probe any further into history that would give clues as to likelihood of gout. I will keep this in mind at the upcoming review.

  8. Tom:

    Since the lateral sesamoid is the most tender, I would be very concerned about it's radiographic appearance. I suspect avascular necrosis. An MRI scan is the best way to differentiate avascular necrosis from other pathologies in the sesamoids. Eric Heit and Rich Bouche, DPM, wrote an excellent article on sesamoid injuries that you may want to review.

    Here also is an excellent book chapter by Rich Bouche on sesamoid pathologies. I consider Dr. Bouche to be the most knowledgeable podiatrist in the US on this pathology.

    Foot orthoses can be used to effectively off-load sesamoid injuries but I suspect, unless the pain is relatively mild or the patient is willing to stop all athletic activities, a lateral sesamoid excision surgery would be the best option long-term for the patient if, indeed, avascular necrosis of the sesamoid is suspected.
  9. W J Liggins

    W J Liggins Well-Known Member

    From K.K. An MRI scan is the best way to differentiate avascular necrosis from other pathologies in the sesamoids

    Precisely. And the appropriate route before considering surgery.

    Bill Liggins
  10. Lab Guy

    Lab Guy Well-Known Member

    Perhaps, Bill.

    In this case, Even if the MRI was negative for AVN and positive for a comminuted fracture or arthritic condition of the fibular sesmoid, I would still recommend surgical removal.

    I would first discuss the prolonged conservative treatment and let the patient know that my expectations were low due to the extent of damage to the sesmoid. I would highly recommend that the sesmoid be removed and would also encourage her to have a second opinion so she can make her own informed choice.


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