Every year many new papers are published in the field of regenerative orthopaedic, i.e. stem cells and PRP. Most of them are clinical papers written by people like me, practicing physicians, working with real patients. You can look at these papers like an exchange of opinions between peers. The papers differs in their value mainly due to gravity of presented medical evidence. Let me elaborate on it a bit more. In our daily life we, even subconsciously, relay on “evidence”. If I tell you that I was in Paris last weekend you will probably trust me and won’t seek any more “evidence”, such as photos, tickets, hotel invoice and so on. You will probably checked my Instagram page though looking for pictures from my romantic weekend! In medicine we need a bit more evidence than somebodies’ word. And the level of evidence determines the quality of published paper. The highest level of evidence is provided by so called RCTs or Randomised Controlled Studies. In these studies people are randomly (usually by computer software) allocated to the groups, one of them being “treatment group” and the other “control group”. The trick is that neither treating person nor treated person knows in which group s/he is. People who analyse the data don’t know either. In that way the study is unbiased. Current problem with regenerative orthopaedic studies is that the power of evidence is mostly not the strongest. It gives a weapon to the opponents who can then claim that “there is no good evidence that stem cells work for arthritis” etc. And here we get to the core of the problem with medical evidence! More often then not the statement “there is no evidence that something works” is automatically read as “there is an evidence that it doesn’t work”. Can you see the massive difference between saying that there is no evidence and that there is an evidence that something doesn’t work? So if somebody says that there is no evidence that stem cells work for knee cartilage damage, this is exactly what it says: there is no evidence. Reasons for the lack of evidence can be multiple: nobody has done a good study, there are technicals difficulties in designing such study etc, etc… So, THE LACK OF EVIDENCE IS NOT AN EVIDENCE OF LACK. This is fundamental truth about medical research which is often very difficult, complex and time consuming. Conclusion: whenever you are offered a treatment, ask your doctor for evidence and be critical in its assessment. Regenexx provides our own Register when one can review the results of the treatments offered in our clinics. This is a good foundation for a constructive discussion about the treatment. (zk)