Update: The results are still controversial and contradictory on PRP and Achilles tendinopathy. This is a repost of a blog from 2010. (The primary reason for the repost is moving material of archival interest to a site which functions better.)
A study published in the Journal of the American Medical Association, Jan. 13, 2010 gave disappointing results in using plasma rich protein to treat non-insertional Achilles tendinopathy. It showed no difference between using a sham injection of saline and combining it with a painful eccentric stretching protocol in comparison with an injection of plasma rich protein injection along with the standard painful eccentric stretching protocol.
The authors note that previous studies did not have good control groups. In this small study, 27 patients were in the placebo group and 27 in the treatment group. The VISA-A score was used to assess improvement. Both groups improved somewhat without a significant difference between the two groups.
The study was called a “preliminary communication” which is often done with small studies. Other studies on similar topics with fewer than 30 individuals studies have also been billed as “preliminary studies”, but when they are talked up afterward, the “preliminary study” status is usually forgotten. As far as study design goes, the design, blinding, and performance of the study seems just right. I am not entirely convinced of the efficacy of the painful eccentric stretching protocol and would have not minded another study group omitting that treatment. Apparently it is not a panacea (or there would not be studies looking to add to the results), although the initial preliminary study made it sound as though it would be. Follow up journal articles by the primary author of the first study have been positive and are referenced below. Others have expressed reservations on the methodology. (see Woodley et. al. 2007 and Kingma et. al. 2006) Eccentric stretching and overload for tendinopathy has mixed results at best in other body areas.
Note: VISA-A is the Victorian Institute of Sports Assessment-Achilles
Platelet-Rich Plasma Injection for Chronic Achilles Tendinopathy: A Randomized Controlled Trial
Robert J. de Vos; Adam Weir; Hans T. M. van Schie; et al. JAMA. 2010;303(2):144-149 (doi:10.1001/jama.2009.1986)
Alfredson H. Chronic midportion Achilles tendinopathy: an update on research and treatment. Clin Sports Med. 2003;22(4):727-741.
Alfredson H and Cook J (2007), A treatment algorithm for managing Achilles tendinopathy, new treatment options, British Journal of Sports Medicine, 41, 4, 211.
J J Kingma, R de Knikker, H M Wittink, T Takken. Eccentric overload training in patients with chronic Achilles tendinopathy: a systematic review. Br J Sports Med 2007;41:e3 (http://www.bjsportmed.com/cgi/content/full/41/6/e3). doi: 10.1136/bjsm.2006.030916 (concludes: Studies on the effectiveness of eccentric overload training in patients with Achilles tendinopathy show many methodological shortcomings)
Woodley, B.L., R.J. Newsham- West, and D.B. Baxter, Chronic tendinopathy: effectiveness of eccentric exercise. Br J Sports Med, 2007. 41: p. 188-199.