there are serious flaws in all 4 "studies" (the 3rd one is not a study but a position paper.)
centeno - everyone went for the injection, so not a crossover study. while he makes it, there can be no comparison to usual therapy, as noone ended up having usual therapy. no control group - ie all got injection. just one sentence by the investigator would skew all the data (ie. "gosh, you havent gotten the injection yet. no wonder you arent better.")
wang - probably best of the 3. but no control. was there any benefit to any of the patients at all? maybe BMAC didnt help, but... if the entire procedure wasnt beneficial at all, then BMAC shouldnt help. also, cohort study and the authors admit level 3 evidence...
the Murphy study was "prospective", but... he did surgery 1 way initially before 2012, then changed his entire practice approach to do surgery a different way after 2012. lends to bias and also speaks as to whether it wasnt the bone marrow but a change in his surgical technique (or the anesthesia, for example) that improved outcomes. maybe it was the fibrin glue and not the bone marrow that made the difference.....