A low dose deca, like 100mg per week will help with the pain for sure. On its own though, not enough to help. He would want to look into things like HGH, Nutrobal, BPC, TB......check out Domestic-Supply and sarms.forsale
I ran deca at 100mg per week for 12 weeks and it worked wonders on my shoulder. I never believed much in the healing properties but months later, I have never had any pain return. That being said, I would never run a year long cycle for any reason.