TENDON PATHOLOGY

be debated, as histopathological analysis of elbow tendinopathy revealed that the areas around vessels were no better repaired than areas distant to blood vessels (7). The possible negative effect of vascularity is that it results in a ‘Swiss cheese effect’ with the ten- don having less tensile capacity. It has been proposed that the amount of vascularity is excessive and well above that needed for repair. Imaging of some abnormal tendons indicates that large areas of the tendon are taken up with vascularity, giving some credence to this perspective.

HOW IS VASCULARITY DETECTED? Ultrasound imaging (US) has been used to image tendons now for 20 years. More recently, magnetic resonance (MR) imaging has also been used to demonstrate abnormal tendon morphology. Ultrasound can also detect fluid movement with colour or power Doppler images; hence Doppler US is able to give a clear indication of abnormal vessels in tendons. In normal tendons no vascularity is evident on US. Magnetic resonance imaging does not have a simi- lar capability to detect tendon vascularity.

Vascularity in abnormal tendons can be easily detected in the patel- lar and Achilles tendons. It also is possible to see abnormal vessels in smaller tendons such as the lateral and medial elbow tendons. In deeper (hamstring) and smaller tendons (rotator cuff), or those with large amounts of fibrocartilage (tibialis posterior), it is more difficult to detect vascularity.

The amount of vascularity visible at any given time in a tendon may be dependent on several things, such as recent activity and muscle relaxation. Patellar tendons examined before and after a game of volleyball showed on average a three-fold increase in vascularity (8).

TENDON PAIN There is clear evidence of neural ingrowth in abnormal tendons that are associated with blood vessels (9). This association extends to a positive relationship between increased tendon vascularity and more pain (10). The association is not absolute, however, as ten- dons can be painful and have no detectable vascularity and vice versa.

A longitudinal study in patellar tendons examined monthly five times over a volleyball season showed that tendons with persistent vascularity were more painful and had more vessels than other ten- dons. Tendons with intermittent vascularity had some pain on days the vessels were visible and days they were not, indicating that the presence of the neurovascular structures is more important for pain than the blood flow in the vessels (11).

Longitudinal studies that have examined the relationship between vascularity at baseline and outcome have also confused the picture, as the presence of vascularity at baseline has not been shown to be associated with poorer outcome in several studies (12, 13).

TREATMENT OF TENDON VASCULARITY Sclerosing treatment Alfredson and colleagues in Sweden have been directly treating the excessive vascularity in painful tendons with injections that are designed to sclerose the vessels. The treatment includes up to five injections each spaced three weeks apart. This treatment has been used in the patellar, Achilles (mid portion and insertion) and elbow tendons. Treatment has been reported to successfully reduce pain in more than 70% of cases (14, 15). Treated tendons have been fol- lowed longitudinally for more than two years, when tendon struc-

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