Two Biomech probs - help required

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Hi two Biomech probs encountered recently:

(1). Male patient young fit healthy plays lacrosse, pes planus foot type no other probs noted or stated. but now encountering pain 6 weeks after issueing polycarbonate orthoses.Both with a rear foot posting of 4degrees pain/aches in peroneous longus/Brevis area posterior to lateral malleolus.Nothing upon palpation.some soreness in the left 5th metatarsal area.Soreness/pain usually comes on around 45 minutes after wearing.Upon examination tonight left device is not as supportive as right when viewed in frontal plane.The right device described as perfect by patient.

Any ideas on what this might be and how to correct the orthoses as/if neccesarey.

(2), Female, fit and healthy no medication decent runner.Dull ache pain in right lateral knee right ITB/glute' area and numbness in right shoulder. always occurs when runing and lasts to a varying degree for approx 24 hours after completeing run which is usually a 10k distance. VAS of pain usually a 3' nagging ache in knee and hip areas.
First occured in 2006, since then has has x rays on both areas and mri nerological tests on all areas and on her brin courtesy of the NHS - all negative results.
Pes cavus foot type/rearfoot varus.with secondary tibial varum.No probs with STJ.mtj or ankle joints qom or rom.

Neutral asics runners, has sedentary job.Pain Never occurs when fell walking or day to day activities.Has hardly run since prob first arose.When she started back a few weeks back problem resurfaced.Previous physio after 10 sessions no positive result after being treated for ITB syndrome.

O/e today left LLD approximately 7-9mm shorter.

Provided patient with pair of slimflex insoles to be used only in runners left device with detatachable raises of 4 & 6mm - all i had at my disposal today.

Any help or thoughts

Thanks

 

Hi Jasper,

Have I understood situation (1) correctly - a patient with pes planus had no problems, you issued foot orthoses anyway and now 6 weeks post issue they have pain in the peroneal region?

If so, remove orthoses. Symptoms will probably recede.

In patient (2) what is gluteal/hip abductor recruitment like? How about proximal control/frontal plane pelvic stability when running? If the therapeutic aim is to reduce tensile loading forces in the ITB then it is no good just thinking distally.

Ian

 

I agree with Ian for patient (1).

For pt (2).
Think about mid-stance to toe-off. The knee is slightly bent and the heel is unloading (if she heel-strikes at all - some runners don't) as the forefoot progressively loads, so you need to tailor your orthoses to the patient and her symptomology. The likelihood is that she will need some forefoot correction.

Some questions for you......
What age is pt (2).
Not sure what slimflex orthoses you are using - are they OTC or custom?
Does she have a longstanding soft tissue injury (of 4 years+ duration) which needs good physio to put right?
Have you acclimatised your patient to her orthoses properly?
On reflection, do you think orthotic therapy is the right way to go with this pt?

 

Some problems caused by improper orthoses that could occur at lateral ankle after new orthotics.

If there was too much forefoot valgus correction, (you are now trying to evert the foot farther than available range of motion) you could get pain at the point of load along the lateral forefoot or the sinus tarsi or both.

If the foot had a more lateral axis than you thought and there was a significant medial heel skive the patient may have become laterally unstable and will increase use of their peroneal muscles and could possibly develop a tendonitis that would be seen at the lateral ankle.

Before you take the orhtotics away, does perfect mean more comfortable than no orthotic? If it does, you should figure out what you did wrong with the left one. When I first got my orthotics I was mostly asymptomatic except for occaisional pains. They have made my life better and have improved performance.

Eric.

 

Do you agree with the assessment of ITBand? One theory on IT band is that it is caused by an adduction moment on the leg at heel contact. To reduce adduction moment on the leg increase force laterally.

Eric

 

Dr.Fuller,

To reduce adduction moment on the leg increase force laterally.Eric

By increasing the force laterally means to have a varus rearfoot post? This pt already rearfoot is in varus, would not a varus post make her heel strike more laterally? increasing the moment arm from the medial tubercle? increase ecccentric contraction of the peroneals?

Would it be fair to assume that the tibial varum creates a abduction movement at the knee and the hip ext rotation would impose increased strain on ITB?


David

 

Hi David,
A varus heel wedge will only increase force laterally if there is significant supination of the STJ. In most people, a varus heel wedge will not supinate the STJ significantly. So, I agree with you that a varus heel wedge would be inappropriate if you were trying to shift force laterally. On the other hand a valgus forefoot wedge will tend to increase the force laterally as will a valgus heel wedge.

Did you accidentally substitute abduction for adduction?

Forces and tibial varum, frontal plane analysis. Free body diagram of tibia with high tibial varum. The downward force from body weight is applied to the top of the tibia. The upward force from the ground is applied by the talus to the bottom of the tibia. With significant tibial varum the force from the femur will be lateral to the force from the talus and this will create an adduction moment on the tibia. (It helps to draw the picture.)

Adduction of the hip or knee will tend to increase tension in the IT band. The IT band runs parallel with the femur, so it seems like there would be little change in IT band tension with pure transverse plane rotation of the femur relative to the pelvis.

Eric

 

Hi Dr.Fuller,

A varus heel wedge will only increase force laterally if there is significant supination of the STJ. In most people, a varus heel wedge will not supinate the STJ significantly. a varus heel wedge would be inappropriate if you were trying to shift force laterally.

In a person with a medially deviated Subtalar joint, a varus heel wedge would minimise the degree of pronation at heel strike? but doesnt supinate the subtalar joint? then how would a varus heel wedge not increase lateral force? isn't a varus heel wedge shifting forces medial to subtalar joint axis lateral to the axis?


On the other hand a valgus forefoot wedge will tend to increase the force laterally as will a valgus heel wedge. [/B

In one the discussions here regarding the use of valgus posting under the heel for medial knee OA i got the impression that a valgus heel-to-forefoot wedge will shift forces lateral to subtalar joint medially therby reducing the adduction moment of the knee.


Did you accidentally substitute abduction for adduction?
i used 'abduction movement' to describe the knee position relative to midline of the body as in genu varum. we were discusing forces so adduction moment was a more appropriate term. my apologies Dr.fuller

Forces and tibial varum, frontal plane analysis. Free body diagram of tibia with high tibial varum. The downward force from body weight is applied to the top of the tibia. The upward force from the ground is applied by the talus to the bottom of the tibia. With significant tibial varum the force from the femur will be lateral to the force from the talus and this will create an adduction moment on the tibia. (It helps to draw the picture.)

Adduction of the hip or knee will tend to increase tension in the IT band. The IT band runs parallel with the femur, so it seems like there would be little change in IT band tension with pure transverse plane rotation of the femur relative to the pelvis.

Eric[/QUOTE]Thank you for this, i wasnt thinking of frontal plane

David

 

You'd be surprised at how little position change you get with a varus heel wedge. Have some people stand on wedges and see how much change in position you get. In my experience, only people with more laterally positioned axes will have a change in STJ axis position.

The explanation of this is that in stance there is a high pronation moment from the ground and equal and opposite supination moment from some structure within the body. The varus heel wedge will reduce the pronation moment from the ground and then there will be a reduction of supination moment from that anatomical structure (and less stress on that structure.)

So, if the STJ does not supinate, there will not be an increase in force laterally. A varus heel wedge will shift the forces medially and this increase supination, or decreases pronation, moment from the ground. If the supination moment is high enough, then you will get supination of the STJ, but in most feet it won't be.

A lateral wedge will shift forces relative to both the STJ and the knee. You can't effect one joint without effecting the other when weight bearing. If you assume the STJ is rigid, you can do the free body diagram on the plantar surface of the foot to the top of the tibia. So, when talking about knee moments you can leave out the STJ.

One of the first things you have to do in biomechanics is get a handle on the terminology. You certainly can use short hand when both people in the conversation know what's going on. I now see that you meant movement of the knee joint anatomy, the top of the tibia and the bottom of the femur, will move away from the midline. The terminology I grew up with, and I think it's more prevelent is that when you describe abduction you are talking about the distal bone, tibia, relative to the proximal bone, femur, when talking about the knee.

Eric