I have a client who drives 35k km per year. He just received a new truck in October, it has very little seat adjustability. Since receiving the new truck he has been c/o bilateral leg and foot numbness while driving. He can work around it with movement of his legs and postural breaks from the vehicle. I’m looking to solve the right problem…anyone seen this before?
Any thoughts are appreciated!
Just one question. Does he have a lumbar support in the truck seat? Sometimes this can be helpful, but sometimes it can cause more of an anterior tilt to the lower part of the pelvis and may increase distortion of the pelvis and sacrum which can alter the nerve flow down the legs. If this is the case, you might have the client put a small wedge pillow under the distal portion of the thighs to see if it reduces his symptoms. For some people, especially those who do a lot of sitting, finding the exact neutral position of the spine where they are most pain free is better than maybe having them try and sit in the “perfect posture” position. In other words, encourage comfort over numbers and angles, though numbers and angles are a wonderful starting place. Hope this helps.
The lumbar support is poor, and I tried a lumbar support roll, but it was way too much for him. It only seemed to accelerate the onset of the numbness. Any thoughts on the quality/ softness of the foam and how much this affects circulatory things? I will try the wedge and see how this affects things!
I find that as a rule a firmer foam is good. However, it sounds like he may have too much of an anterior tilt already. You might also try the lumbar support roll at the sacrum instead of at the lumbar curve, or the foam wedge as previously suggested. I’d be interested in knowing what works best. Especially as I will be teaching an injury prevention class to van drivers next week! Thanks.
Thanks! I will follow up and let you know!
Can you help me to understand the use of the foam wedge? Is the thought that the seat pan may be sloped downward too much, or not enough? I
THe direction that I seem to be leaning toward is that- there is too much angle between the hip and the knee ie. the hips are much lower than the knees. I think our first try is to repad the seat, by raising the back and shaving some off the front to flatten it out. We’ll also change the quality of the foam, so there isn’t so much bottoming out on the actual frame of the seat which I suspect is the source of the circulatory issues.
Good thought about the compression of a small piece of foam. I was thinking more of a large wedge, big enough to support the width of both thighs, and covering the area from the knees up to the sacrum. And firm foam would be the best so it gives support more like an actual seat. I have some concerns about shaving off the front of the seat, as this may increase the angle between the hip and the knee? Any other feedback out there? Thanks.
I question if the problem is all seat related. Could the position of the gas pedal or the stiffness of it contribute to his numbness? Does he have any new or underlying lumbosacral dysfunction that is not being addressed? Good Luck
Tebble Cassel, PT
It may be he is having an entrapment of the tibial nerve at the ankle. Tarsal tunnel syndrome causes numbness and tingling of the great toe and 2,3 digits. Could also be confused with a discogeneic problem. But,if he doesn’t have back pain or sciatic nerve root problems that should be ruled out. He should be referred to an ortho. or podiatrist.
Unlikely that bilateral leg and foot numbness while driving would be caused by the tibial nerve at the ankle. Unilateral foot numbness (plantar surface) possibly, bilateral foot less likely, bilateral leg much less likely, unless the posterior tibial nerves were being bilaterally compressed at the tendinous arch of the soleus (back of the knees). More likely scenario is centralized compression at the level of the spine or bilaterally at the sciatic nerve in the hip or thighs (which is why pelvic positioning would effect symptoms). Don’t necessarily need an ortho or a podiatrist to figure that one out.
I’ve seen this problem several times over the years. In each case the truck seat had a seat-to-backrest angle that was tight, forcing the driver’s torso into an upright orientation and at the same time forcing the lumbar spine and hips into extreme flexion. Also in each case, the driver was male and had limited hip flexion mobility (i.e., less than 90-degrees flexion unless the hips are widely abducted). I have worked with hundreds of truck drivers, and cannot remember even one case in which the driver sat with anterior rotation of the pelvis, as some other replys suggest is at issue in this case.
In the cases I worked with, symptoms disappeared with a greater seat-to-backrest angle, achieved primarily via reclining the backrest and sometimes also by raising the buttocks on a seat wedge. In this scenario, a lumbar support at best does nothing, and at worst exaccerbates the problem by acting to decrease the seat-to-backrest angle even more.
In some of these "problem" truck seats the backrest cannot recline. The driver’s cab is small, and the back wall of the cab nearly touches the backrest so there’s no place for the back rest to recline into, even if it could. I never found a good solution for this short of getting rid of the truck and replacing it with one that allows sufficient backrest recline. My attempts to use seat inserts designed to open the hip angle, failed. They pushed the driver out of the seat pan and created instability in the seat.
Let us know what you discover. Good luck.
Eileen Vollowitz PT
Hi folks – I have read thru the trail with some interesting and pertinent recommendations.
But don’t forget your anatomy – the vascular system got missed in all of this! And there is increasing research arising the medical literature so I suggest you consult this for your answer. What would happen if the seat pan of a chair or in this case truck seat did not have adjustability for seat pan length? The Popliteal Artery; Inferior Gluteal Vein along with the sciatic nerve, Politeal Nerve may all be compressed over a period of time due to slow deformation of the overlying muscles and soft tissue in and around the popliteal fossa.
Next recall your course work in Physiology particularly the bodily reaction to chronic compression of the nerve (eventual demyelination) & loss of localised blood flow to the nerves themselves) and the veins (collapse due to lack of muscular support in the veins themselves) and potential vasospasm in the artery.
And voila you have eventual numbness in bilateral (and bilateral is the key clue that this is vascular related) legs/feet.
Solution? adding a full support into the back piece will shortern the length of the seat pan therefore preventing mechanical compression at the vulnerable popliteal fossa.
I always tell my consultants – go back to your anatomy and physiology – and you can’t go wrong in determining first, the cause and secondarily, the cure!
Hope this helps
Maybe its the sciatica nerve. Google that and maybe it can help. Things you could try is installing a better, custom seat (if possible) or try different shoes/clothes. Maybe he can keep changing postures too. And actually it may not be related to the truck.
Men have become the tools of their tools. – Henry David Thoreau
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Not to flog a dying horse or however that goes – please go back and read my response as guessing what is wrong versus using solid clinical reasoning may result in our professional making things worse (and then you lose trust on the part of the client and the individual)
Instead the Red Flags for medical issues MUST be ruled out first – that being neuroligal and vascular as well as neurovascular. Only once that is ruled out would we look at ergonomic issues – and again even then never make the jump in causation by virtue of someone saying they have symptom xyz therefore it is the job or a certain task.
A formal, informed and scientific approach must be used in these and all cases particularly if we want to ensure our profession is respected and valued.
JE Sleeth OPC Inc
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