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Fixed external hip position with compensatory pronation - is it necessary to correct?

Discussion in 'Biomechanics, Sports and Foot orthoses' started by JAD, Jun 30, 2010.

  1. JAD

    JAD Welcome New Poster


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    Hi,

    60 year old male. Right knee degenerative, left knee - early signs and symptoms of degenertaive knee. No xrays of hip, however patient has discomfort in hips, however location of pain in hip and hamstrings - undefined.

    Gait: externally rotated bilaterally,
    Excessive movement of left pelvis through swing. RF pronation contact through to propulsion.

    Main issues from biomechanical analysis:- hip fixed in external rotation on right (no internal rotation), left minimal internal rotation
    - malleolar torsion 22 degrees roughly bilaterally, femoral component appears to be in a greater externally rotated position
    - limb length assessment - right tibia close to 1cm shorter - in stance pelvis and shoulder - appears level
    - jacks test positive bilaterally - improved with foot correction
    - supination resistance moderately hard bilaterally
    - elongated first bilaterally
    - lunge test positive
    - arch profile - left more planus than right
    - RCSP left 2 evr, right 4 evr

    Due to the fixed external position, I believe pronation has increased. Because there is basically no internal rotation possible through swing of the hip, and femur.

    Could controlling the pronation possibly cause more issues (hip, back, knee) ie with shock related issues etc. Is this pronation necessary now that there is no or little internal hip rotation. Or should this compensatory pronation be addressed?

    Due to the fixed externally rotated position of the right hip, is this causing the left pelvis to move forward anteriorly, to compensate for a lack of internal rotation. My thoughts are this, and that this pelvic motion is causing increased lumbar motion etc possibly increasing spinal nerve impingement etc.

    Also does anyone have any suggestions to the prevention of the forward movement of the left pelvis?
     
  2. Hi JAD,
    1st thing I would do is make the patient get some Hip x-rays- so you know what you are dealing with.

    If you reduce the STJ pronation yes you may increase the Hip problems. If the hip is badly degenerated with OA changes a hip replacement may solve alot of the patients problems.

    But get the Hip X-rays done 1st, then consider treatment from the foot up.
     
  3. David Smith

    David Smith Well-Known Member

    JAD

    you wrote
    What exactly do you mean by fixed external hip position? Can I take it that the hip does have some RoM in terms of the transverse plane (vertical y axis in stance)?

    These are my thoughts:

    If I make the assumption that (as you say later) you mean the hip has no internal rotation then does this mean that in terms of the knee position the hip has no internal rotation past knee straight ahead? Therefore the central or neutral position of the hip is externally rotated. This is a common finding for me.

    In this case the subject often adopts a toe out foot placement angle during stance phase. This position allows sufficient internal rotation of the hip during contralateral swing thru. I.E. If the foot is placed straight ahead then during contralateral swing thru the hip will come to its end range of motion and some other compensation takes place. In the latter case there is a tendency to increased torsional forces in the knee and often this is avoided by supination of the STJ and external rotation of the tibia.

    In the former case the toe out foot placement angle results in increased pronation moments about the STJ since the posteriorly directed braking forces become closer to perpendicular to the STJ axis. This then will have the tendency to pronate the STJ and internally rotate the tibia.

    You will see then that this results in the tendency to internal rotation of the hip joint, which reduces the hip rom available for contralateral swing thru, much the same as the example of straight ahead foot placement.

    The problem now is that potentially it will be much more difficult to supinate the STJ from the pronated position and increased torional forces will be occuring in the knee joint.

    If you now increase supination moments from GRF by using an appropriate orthosis then this will make supination of the STJ from femoral tibial axial torsion much easier and therefore reduce torsional forces in the knee.

    This explanation takes no account of any +/- malleolar torsion and you also need to take account of the relative rotations at the knee hip and malleoli but your patient's seem ok.

    You seem to describe an ascending compensation where the patient changes the pelvic position. I.E. they lead with the hip opposite to the one with the reduced RoM. This can result in a toe in and short swing thru on the contralateral leg i.e. the left in this case.

    The same principle applies as before re the increased supination moments from the orthosis but also a lateral gait plate extension can make the right foot (in this case) toe out and allow normal pelvic position and symmetrical swing thru .

    Often, to achieve resolution of altered skeletal position, this will also need referral / cooperation from a physio to address muscle shortening due to the long term effects of variations in the relative anatomical limb and joint positions.

    Sometimes although you can measure or see a short limb the hips are level but this is a result of assymetrical muscle tension. Mobilising the ankle joint will often result in the hip level difference showing up and this can then be addressed with a heel lift. The opposite is usually true, I.E. the limbs measure equal but there is a hip level difference, mobilising the ankle joints results in level hips, ilium crests and ASIS and no heel lifts are required.

    You might see from this explanation that addressing the pronation would probably be a good thing (other variations not withstanding) and reduce knee torsion that may be the cause of joint wear and pain.

    Have you tried stretching out the hip external rotators using isometric stretching technique i.e. Starting at the internally rotated position, hold hip in isometric tension (resisted external rotation) then relax and manually stretch the muscle group (manually internally rotate the hip with appropriate force usually applied via the foot and ankle). See if internal RoM increases if it does then treat appropriately with stretching and or ref to physio.

    Does this help or make sense?

    Cheers Dave
     
  4. Griff

    Griff Moderator

    Dave,

    Bit off topic but could explain this concept further for me please? I often see increased STJ pronation moments with an abducted foot position (e.g external tibial torsions etc) and have mulled over a mechanical explanation but end up with a drawing which looks like the work of M C Escher.

    Cheers

    Ian
     
  5. efuller

    efuller MVP

    Hi JAD, I have a few questions about your terminology. Once, I understand what you are seeing I might have some suggestions.

    Left pelvis? Do you mean there is lots of transverse plane motion of the left hip joint when the left foot is on the ground? Or are you talking about a lot of transverse plane motion of the swing leg?

    hip fixed? I assume there is internal and external rotation of the hip. Do you mean that at the most internal position the knee cap still points externally?

    Is a positive Jack's test when you see internal rotation of the talus when you attempt to dorsiflex the hallux in stance as Jack originally described? Or is positive normal/ average motion of the foot when you try and dorsiflex the hallux. On the arena we've discussed that there is no accepted definition of what a positive Jack's test is. What do you see when you try and dorsiflex the hallux in stance.

    There might be a definition of a positive lunge test, but not everyone knows what it is. It would help if you described what you saw when the lunge was attempted.


    I am not being critical. I just want to understand what you are seeing.
     
  6. efuller

    efuller MVP

    This is not quite of topic as JAD asked about compensatory pronation for the abducted angle of gait.

    I'm not sure I agree with Dave's explanation. True, the braking force will be more perpendicular to the STJ axis. The location of the STJ axis is determined by the shape of the facets of the talus and calcaneus. As the talus externally rotates the STJ axis will externally rotate. The braking force is a frictional force from anterior to posterior applied by the ground to the foot during the first half of stance phase. With straight ahead gait this frictional force is close to parallel to the STJ axis and when the talus (and the axis) are more abducted the frictional force will be perpendicular to the axis. During the second half of stance there is a propulsive frictional force applied by the ground to the foot that is from posterior to anterior and this will tend to cause a supination moment. This is why I disagree with Dave's explanation. It is true only for the first half of stance phase.

    One observation that I have made about people describing abducted gait is that they may be thinking that medial column loading is the same thing as STJ pronation. When the foot is abducted in gait there is a tendency to roll over the medial side of the foot putting more ground reaction force under the medial forefoot. With STJ pronation you can get high loads on the medial forefoot, if there is sufficient range of motion of the STJ available. But, you can get high loads on the medial forefoot in other ways besides STJ pronation. I believe that a lot of pathology that has been attributed to STJ pronation is actually caused by high medial forefoot loading.

    In answer to JAD's question on whether he should address the pronation, I would answer address what the patient is complaining about. There was no mention of any foot complaints. There was mention of knee arthritis. If the patient had genu varum, I would avoid (think hard about) a medial heel skive or varus heel wedge. If the patient had genu valgum, I would use a medial heel skive to treat both the knee and the "pronation" of the foot. (That's just general advice. There are other considerations.)

    Regards,

    Eric
     
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