I broke the top of my fibular last year. I have approx. 95% use of my knee now. The issue is that on a normal bicycle, the upward peddle position bends my knee to the point that it is very uncomfortable. I have looked into recumbent bikes but, first they are out of my budget and second, I really want to bike sitting up straight. I was thinking a shorter crank would help as well as a "comfort" crank forward bike. Any thoughts?