It is interesting to note that they are subjecting the controls...

It is interesting to note that they are subjecting the controls to a treatment that is guaranteed to be useless but that is the nature of trials (not a criticism) and this trial is much better in design than the Celgro trial (which admittedly is hard to do any other way). This is a proper randomised controlled trial but there will be no potential upside for the controls.

https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD004016/epdf/full

The primary outcome is tendon regeneration assessed by MRI.This will show whether the tendon has repaired itself, tendons don't repair themselves generally. The secondary outcomes are also important as a degree of tendon repair without much improvement in pain/function is of little value

As someone who has one of these injuries I will be watching closely though I have to admit the results will have to be pretty good before I let someone biopsy my patella tendon to fix something I have lived with for years, no doubt at large expense.

The alternative treatments for partial tears is physio and live with them with a variable amount of disability or have surgery. Based on the study protocol, the post injection restrictions are vastly preferable to surgery, so if this study is a success this stuff will be a winner.

It should be noted that they are only looking at 1 particular tendon which admittedly is the tendon most commonly torn and they are excluding the elderly who represent a large cohort of tears.