Strategies in treatment of tendon overuse injury. The chronic painful tendon

The etiology and pathogenesis to chronic tendon pain is unknown, and treatment is known to be difficult. Treatment is often based on opinions and not findings in scientific studies.

Recent research, using the intra-tendinous microdialysis technique, has shown that in chronic painful Achilles-, patellar-, and extensor carpi radialis brevis (ECRB) tendons, there were no signs (normal Prostaglandin-2 levels) of a so-called chemical inflammation. Furthermore, in biopsies from chronic painful Achilles tendons, pro-inflammatory cytokines were not up-regulated, again showing the absence of an intra-tendinous inflammation. Consequently, if the purpose is to treat a chemical inflammation, there is no science backing up for treatment of theses conditions with anti-inflammatory agents (NSAIDs, corticosteroidal injections). Interestingly, Substance-P (SP) and Calcitonin Gene Regulated Peptide (CGRP) nerves have been demonstrated in close relation to vessels in biopsies from these chronic painful tendons, indicating the existence of a possible so-called neurogenic inflammation.

Using ultrasonography (US) + color Doppler (CD), and immunhistochemical analyses of biopsies, a vasculo/neural(SP- and CGRP-nerves) ingrowth in the chronic painful tendinosis tendon, but not in the pain-free normal tendon, has recently been found. A specially designed treatment, using US- and CD-guided injections of the sclerosing agent Polidocanol, targeting the neovessels outside the tendon, has in pilot studies on chronic painful Achilles-, and patellar tendons been shown to cure the tendon pain in the majority of patients. A recent randomized double-blind study, verified the importance of injecting the sclerosing substance Polidocanol.