The complete list includes prolotherapy, prolozone injections, PRP injection, n STRIDE injections, and mesenchymal stem cell injections (as part of a Health Canada approved trial). Of these Prolotherapy and PRP are the oldest and hence, have the most evidence to support their use. In terms of cost, Prolotherapy is the least expensive as it is the oldest treatment, while stem cell injections are the most expensive. There are very few head-to-head trials comparing stem cell injections with other regenerative medicine approaches. Of the ones available, some show that outcomes of stem cell injections for knee osteoarthritis are no better than outcomes with PRP injections while others suggest that stem cell injections are superior. On a theoretical basis, there is a suspicion that stem cell injections should be more effective as they contain higher concentrations of stem cells and various growth factors, however, there is no proof that it is true.