I have been having issue on and off over the last six months (perhaps more) with chronic lower back pain. I have been working with my prosthesist on the height of my leg, as oftentimes lower back pain will result from being too high or too low in the adjustment, but to no avail. I have considered it could be my foot, as the current model is much more flexible than the one I wore for several years before. It walks better, but is also much more "spongy" than the higher category foot I was on.
I recently read an article by an Olympic cyclist BKA, who also commented on lower back pain, and how she eliminated it through doing away with the foot and going to a shorter crank arm on that side. I have done some experimentation with eliminating the foot for my cycling leg, but found that I was unable to release from the cleat without the leverage of a foot. I have done modifications to my (now) cycling leg for height correction in lieu of ankle flexion as well as trimline modification to avoid "pinch" behind the knee. I develop much better power with my residual limb than I did when I started and have corrected issues with my other knee doing so.
The thing that I find confusing is that riding my bike is 110% more comfortable to me than even walking. I no longer feel any discomfort related to the amputation while on the bike, or at least to a point that it is very uncommon. Stretching out on my bike makes my back feel better at least for the time I am riding. Both my PCD and my Chiro have recommended riding as often as possible for my back. I have also been told to work on abdominal muscles to help support my core. Unfortunately doing that aggravates my back almost immediately. My Chiro has been the best relief so far. A couple of adjustments with him make my back feel better almost right away, but I feel a whole lot like I am just putting a band-aid over a bigger issue. Within a few weeks of not seeing him, the pain returns. Medications have no effect whatsoever. I have muscle relaxers that would put down an elephant and they don't help at all aside from knocking me out at night for a few hours. I should also point out that I have had X-ray and MRI to confirm that there is no issue with disks or vertebra.
I was wondering of any other BK/AK-A have recurring issues with your lower back, and how you have dealt with or eliminated those problems.