In Reply: Dr Creaney suggests that the eccentric exercises may have overshadowed the possible beneficial effect of PRP. The assumption is that if a tendon is already being stimulated to heal as fast as possible, there would not be much additional benefit from adding a second treatment. However, this is the crux of the matter: we evaluated the additive value of PRP injection to these exercises, given that the exercises have been shown to be effective and should be included in usual care. In addition, to inject PRP in isolation is not recommended because in an animal study the improvement in tendon mechanical properties occurred when PRP was combined with mechanical stress.1 To our knowledge, all clinical PRP studies reporting effects in tendinopathy have used it in combination with strengthening programs.2 Therefore, which of the 2 treatments, PRP or exercise, is more effective cannot be evaluated in our trial. Such a trial would be of interest if there were reason to believe that PRP injection alone is better than exercise treatment alone, or to assess the cost-effectiveness.
de Vos RJ, Tol JL, Verhaar JAN. Platelet-Rich Plasma for Treatment of Achilles Tendinopathy—Reply. JAMA. 2010;303(17):1696-1698. doi:10.1001/jama.2010.521