Rumors from whom ? From a band of liers only having pleasure to defame top athletes ? From a group of losers without talent, passion, stimuli and motivation, who live all their life for envying who is able running faster than them ?
The attempt to manipulate the reality, and to sell stupid, not real and personal opinions as TRUTH, is one of the more slimy, shameful and disgusting behaviors people can have, and who spreads those false accusations is himself a revolting person.
Kenenisa had big problems not in one knee, but in one calf, with the rupture of some muscle fibers that stopped his activity for more than one year (the whole 2010).
After that injury, that happened during the race of Seven Hills in Nijmegen, he was no longer able to have continuity in training, and never competed between the Cross of Edinburgh (9th Jan 2010) and the WCh 2011 in Daegu (28th August) when he dropped out after 7 km, for winning, after 19 days, the only other race of the season : 10000m in Bruxelles in 26'43"16.
Kenenisa was no more able to run with spikes on track at high speed, also if in 2012 tried to run on the track for winning another Olympic Gold, but at the end understood was no more possible to reach the same shape of the past in something fast, for his problems when had to run fast. This is the main reason because moved to marathon.