Neovascularisation in chronic tendon injuries detected with colour Doppler ultrasound in horse and man: implications for research and treatment.

Recent research on chronic painful Achilles tendons in humans using ultrasonography and immunohistochemistry, has demonstrated an association between neurovascular ingrowth and tendon pain. In horses, chronic debilitating tendon conditions are well-known to be very difficult to treat, and the background to impaired function and pain is not scientifically clarified. In a collaborative research project between the Sports Medicine Unit in Umeå and Strömsholm Equine Hospital, grey-scale ultrasonography (US) and colour Doppler (CD) examination were performed in ten horses with chronic tendon injuries (>3 months) and a control group of six healthy and asymptomatic horses. In all symptomatic tendons, but not in any of the tendons in the control group, neovessels were seen in the area with structural tendon changes. The neovessels found in the horse tendons looked similar to what has recently been presented in human Achilles tendons. These findings motivate evaluation of the same treatment, a sclerosing injection that was demonstrated recently to give promising results in the treatment of chronic Achilles tendon injuries (tendinosis) in humans.