I had a ankle fusion 10/2017 and had to have new cadaver bone put in 2/25/2018.My 10 week check x ray had the rod broken where a month prior the rod was ok.I was off my leg with a boot on and put no pressure on my leg.What type of force could cause such a thing?I have no pain and did not fall or was not in a accident .Please explain any causes.Thank you.