I had PDO feather lift Jan 2017, it was a waste of money. I'm scheduled for mini neck facelift Jan 2018, is it safe? (Photo)

"Thread lifts" are beginning to regain popularity because of the increased safety and more predictable results than in the past. However, they will never replace or achieve the results of a surgical face or neck lift.  To compare a thread lift to a true neck lift of any kind would be unfair to patients and both procedures. Although patients may get excited to hear its done under local anesthesia,  those who have become part of my practice know that I perform all of my facial plastic surgeries (including a variety of facelifts) under local anesthesia as well, which creates a level playing field when it comes to that part of it.  In the right patients, I have found that the results of dissolving PDO sutures are worth the effort. For patients whose goals and aging patterns require surgical treatment, nonsurgical options like ulthera, thermitight, PDO, Instalift, etc. (which I perform frequently on the right patients with great success)  are a waste of time and resources.  That being said, I have not found any problems doing a facelift for patients who have previously had any of these procedures. 

Many of my facelift patients come to me for just that reason: they’re unhappy with their thread lifts.  I am not a fan of feather or thread lifts at all. They don’t last long.
Based on your photo, though, I’d recommend a full facelift with fat grafting and neck lift with platysmaplasty rather than a Mini Lift, because you have significant volume loss and sagging in your mid face as well as your lower face. Doing just a Mini Lift would probably not feel very satisfying to you.
It is perfectly safe to have either a Mini Lift or a facelift (rhytidectomy) after thread lifts; the threads can be removed during the procedure. I hope this helps.

In my experience operating on patients after they've had threads place has not been a problem, as long as there are no signs of infection at the time of surgery.  Be sure to discuss with your own surgeon.