That's pretty much what I had come up with. This is a subject of particular interest to me as I'd like to run a tren cycle, but I'm coming off an ACL tear that may(I stress may) have been precipitated by a testosterone cycle and I'm very apprehensive about any negative impact to my joint health.
I'm going to just run through my current train of thought on the subject and anyone and everyone can please feel free to throw your own thoughts in.
To my knowledge the AAS that have research demonstrating a positive effect on collagen synthesis are Primo, Anavar, Nandrolone, and EQ. All of these are anabolics with fairly mild androgenic qualities. Testosterone is know to hinder collagen synthesis and is fairly androgenic. Based on this, I would infer that the more androgenic something is, the more likely it has a negative impact on joint health.
There is one problem with this theory I can see right off the bat.
How do you explain winstrol? A fairly mild anabolic with few androgenic properties that is know to cause joint pain. Well, I've seen it written(http://www.T-Nation.com/readTopic.do?id=354624) that winstrol does in fact increase collagen synthesis, but it negatively affects collagen cross-linking integrity so the ligaments are more brittle in turn. So perhaps Winstrol is simply an oddball in the bunch.
I also have another reason I belive Tren negatively impacts joint health, but it's even less scientific then what I pulled out of my ass and used to filled the space above with. Tren is know to provide incredible gains, even superior to Test according to many. And we all know the greater the risk the greater the reward. So it's unlikely that an anabolic that is both more anabolic and more androgenic than testosterone would lack one out of its multiple side effects with the majority of them already present(Acne,hairloss, etc) and a few of its' own as well(night sweats).
Note to any new guys reading this. There are hundreds of threads on this board that will help you plan a cycle and provide good overall AAS advice. This isn't one of them. I'm just throwing crap out there for the sake of discussion.