I have mild to moderate facet joint hypertrophy at l5/s1 worse on right side had cortisone & nerve block injections but pain is getting worse?

Platelet Rich Plasma. PRP is an offered treatment that has shown good success however is considered experimental at this time. The basic theory is it helps to strengthen the ligaments around the facet joint using your own platelets/growth factors and therefore reducing stress on the joint by tightening them up. As far as I know its safer than steroid injection. Pretty cool stuff. Check out regenexx.com.
May not be source of. Very common to have abnormalities in one area of back on MRI and have source of pain be in a different structure, facet blocks are usually test blocks, if relief is significant for a period of 6-8 hours after block, then i would consider a radiofrequency ablation of the nerve to that joint, if no relief than evaluation for a different structure as source of pain is warranted.
Medial branch nerve. The medial branch nerves supply the facet joints. A nerve block of these nerves will temporarily relieve the pain and is done as a diagnostic procedure. If your pain is relieved by the injections, longer lasting procedures can be done to give you pain relief (either a nerve destruction procedure or injection of steroids into the joint).