I have used a Drive wheeled walker and for almost 10 years it has served me well. After multiple spinal surgeries and joint replacements I find that I need more help than it offers. I am sorry in need of an upright 4 wheeled walker with the front wheels preferably being 10". I'm told by suppliers that Medicare covers them as "wheeled walkers" and suppliers don't accept assignment because what Medicare pays is less than the suppliers have to pay for the product. I  elder,want to stay active but am in constant pain because of my conditions and standing straight (as I will be able to do with one of these walkers ) will improve my QOL.  I have been looking for a USED upright walker to no avail. I have about $200 to pay or hope someone will accept Medicare assignment. I do have a prescription from my Neurosurgeon. I appreciate whatever help/guidance you can give. Thank you so much.  Karen Pierson.