No, Primo or any other AAS is not a good idea until you can get your BF% down under 16% ideally under 14%... I can tell you this for sure about AAS.
In any cycle stack you need to run Testosterone as the main building block of it. If you dont incorporate Test you can run into complications associated with low Test like ED problems...
Talk to your doc and see what your hormone levels are. You could maybe benefit from a testosterone replacement therapy (TRT) dose of Testosterone if you are deficient...
You need to find some type of cardio you can do that doesnt bother the knee. Hit the heavy bag or speed bag. Elliptical machine, bike... You dont need to run a cycle of AAS to lose weight!!!
Shooting yourself up with massive amounts of Human Chorionic Gonadotropin (HCG) wont do it either man. You could do some fricken clen, ephedrine, meth or crack and it will melt the fat away if your heart doesnt explode in the process!
There is no magic bullet... no magic pill... Do some cardio bro and keep your diet in check and you will lose some weight!