Hi all Simon wrote:
:
>I am seeking a biomechanical opinion on a rather complex case.
>
>I have seen a 27 year old lady who has a polio affected right lower limb
>due to adverse reaction to polio vaccination.
>
>She has no active muscle power below the knee, grade 2 quadriceps and
>grade 3 hamstrings.  She also has reduced muscle poweraround the hip.
>
>On examination she has tight hamstrings (popliteal angle 40 degrees),
>reduced ankle range (5 degrees dorsiflexion at ankle with knee extended)
>and a laterally displaced STJ axis. MTJ and forefoot ROM's are not
>alarming.  The right leg is short 20mm.
>
>This young lady has presented with severe medial midfoot pain which is
>intermittent.  The pain is induced normally on uneven ground with
>increased walking speed ( hobby is hill walking).  The result of this
>short sharp pain is increased swelling around her navicular,/medial cuneiform.

Normally, you would think of PT muscle problem with that kind of symptom,
but if there is no muscle power then muscle or tendon problems are less likely.


>She currently walks in a carbon fibre knee ankle foot orthosis with high
>medial midfoot flange,lateral forefoot flange and a 6mm lateral heel skive
>holding her foot in a supinated positon.  Her lack of ankle ROM is
>accomodated with an extrinsic heel  raise and external heel raise fo leg
>length discrepancy.  Fine tuning has been performed with GRF data and 2-D
>video analysis.

Do you mean medial heel skive?  I would assume there are no marks on the
skin from irritation from the device.  High medial flanges can cause
discomfort.


>Despite this she continues to intermittently suffer this "midfoot collapse".
>
>Passively it is possible to mobilise her navicular medially 12mm in
>relation to her navicular and medial cuneiform.  MRI shows that ligaments
>are intact but "possibly elongated" but her talo-navicular joint shows
>early OA response.

Do you mean in relation to her talar head?


>Her ongoing management is in "limbo". I have been asked for biomechanical
>opinion on surgical procedures and conservative management option.  The
>orthopaedic team would like to perform a percutaneous TA lengthening  and
>talo-navicular-medial cuneiform fusion.

The TA lengthening should really be looked at carefully.  Is it indicated
by what is seen in gait?  This might be a case of treating the measurement
without looking at the big picture.  If if is a foot with severe medial
collapse with forefoot abduction (or rearfoot adduction) then this may or
may not be caused by an equinus, especially since there is no muscle
strength in the calf.  The problem is more likely to be related to the MTJ,
medially deviated STJ axis and absence of posterior tibial muscle
strength.  Since this limb is shorter by 2 cm it seems unlikely that a TAL
would help.  What was the range of motion of the ankle with the knee flexed?

A TN fusion will essentially fuse the STJ.  If the OA is bad enough, I
would agree with Kevin in considering a triple.  But 27 is still quite
young and she seems like she wants to be active.  If it were my foot I
would wait until the TN OA was unbearable.  That is if I'm imagining the
foot you are describing correctly.

Cheers,

Eric Fuller

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