Platelet-rich Plasma injections

I've been fighting some major tendonitis in my elbow this past year and a half. Sometimes it gets so bad I can hardly turn a door knob. I've gotten a couple cortisone steroid injections. They last about 3-4 months. They aren't great for your joints so was looking into Platelet-rich Plasma injections. I believe its the same therpy Tiger got in his knee. Anyone here have any experience with these? Effectiveness? Long lasting?

Here in Canada, the steroid injections are covered by government health care but the plasma injections are not and cost almost $400.

My father had severe tendenitis in his elbows and knees pains when I was a teenager in the early 1960's. He played golf three or more times a week in season and in the winter, we skied every weekend. He took cortisone injections every few months and it enabled him to play golf and ski but he was advised that continued cortisone use could be hazardous to his health. Then an older cousin of mine who was finishing up his chemistry degree at Cal Tech told him about the wonders of vitamin C. One of his profs was Dr. Linus Pauling who made quite a stir with his book in the late '60's. So my father found a health food store locally that sold ascorbic acid (vitamin C) in powdered form and started taking "mega doses" of about two grams per day. He never had to get a cortisone injection again and was playing golf well into his upper 80's. I have one of his trophies for a club championship when he was 71. Not a senior championship either.