This looks like a gear strut failure. Has happened twice before at FX in MD-10's.
If true, they need to take a long, hard look at their maintenance practices. FedEx still operates 40 MD-10s (well, may 39 now
) with an average age of nearly 39 years.
FedEx is replacing their MD-10s (and eventually MD-11s) with new-build 767F. However they're taking the new 767Fs at about one/month, so it's still going to take a few years to replace all those MD-10s.