A few doctors prescribe it for that off label indication. No data on actual humans for joint or tendon issues, but lots of anecdotal information. The witch hunt on anabolics put a stop to a lot of the research that was taking place before 2005.
https://www.excelmale.com/forum/threads/1387-Anabolic-Androgenic-Hormone-Prescribing-Indications
Here are in-vitro and animal data:
Am J Sports Med. 2004 Jun;32(4):934-43.
Nandrolone decanoate and load increase remodeling and strength in human supraspinatus bioartificial tendons.
Abstract
BACKGROUND:
To date, no studies document the effect of anabolic steroids on rotator cuff tendons.
STUDY DESIGN:
Controlled laboratory study.
HYPOTHESIS:
Anabolic steroids enhance remodeling and improve the biomechanical properties of bioartificially engineered human supraspinatus tendons.
METHODS:
Bioartificial tendons were treated with either nandrolone decanoate (nonload, steroid, n = 18), loading (load, nonsteroid, n = 18), or both (load, steroid, n = 18). A control group received no treatment (nonload, nonsteroid [NLNS], n = 18). Bioartificial tendons' remodeling was assessed by daily scanning, cytoskeletal organization by staining, matrix metalloproteinase-3 levels by ELISA assay, and biomechanical properties by load-to-failure testing.
RESULTS:
The load, steroid group showed the greatest remodeling and the best organized actin cytoskeleton. Matrix metallo-proteinase-3 levels in the load, steroid group were greater than those of the nonload, nonsteroid group (P <.05). Ultimate stress and ultimate strain in the load, steroid group were greater than those of the nonload, nonsteroid and nonload, steroid groups (P <.05). The strain energy density in the load, steroid group was greater when compared to other groups (P <.05).
CONCLUSIONS:
Nandrolone decanoate and load acted synergistically to increase matrix remodeling and biomechanical properties of bioartificial tendons.
CLINICAL RELEVANCE:
Data suggest anabolic steroids may enhance production of bioartificial tendons and rotator cuff tendon healing in vitro. More research is necessary before such clinical use is recommended.
http://jbjs.org/article.aspx?articleid=180965
http://www.sportsmedres.org/2012/01/can-anabolic-steroids-be-used.html