If you're older, I doubt it. If you're young (reckon < 30 years) and have some serious knee issues, an insurance could approve such an expensive treatment. It all depends if it's approved by a board of docs as a viable treatment. I'd say it's too early for that. A private insurance is much more likely to pay for this, it's for people who earn a bit more money though as the premiums are quite high.
Let's face it, these kind of treatments are for professional athletes. No one cares if your knee hurts if you are just a regular, perhaps old dude, health insurance or not (btw, it's not state-funded, at least not entirely). For instance, old people get knee replacements done regularly around here and doctors and clinics make a ton of money with that, but people doubt how much of an improvement it is for the patients. Very invasive, costly, range of motion not nearly as good as a real knee, painful etc. etc. The system is good if you are seriously ill and lost your job and such, but for "regular" stuff it's as good or as bad as any paid insurance.
From what I hear, the dude who invented this blood cell treatment is clearly focussing on making money out of it and opened a clinic in LA for the rich and famous already so he won't care about social security-insured Germans any time soon
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