I'm afraid that the frequent injections meant to heal the tendon have actually made the tendon weaker and susceptible to tears. I think Nadal needs better medical care than he has received so far. It is a bad sign that the tendon is torn yet it took the doctors many weeks to come to that realization. When the stakes are this high relying on quacks is stupid.
There is no magic pill. Those injections were what allowed him to play and win slams despite his poor knees. If it weren't for those injections maybe his career or slam titles would've stopped in 2009 after he pulled out of wimbledon.
But there is a limit. Medical treatments can only do so much. nadal has definitley taken advantage of all the state of the art treatments there are out there.