Imaging of intratendinous distribution of glucocorticosteroid in the treatment of Achilles tendinopathy. Pilot study of low-field magnetic resonance imaging correlated with ultrasound

Recently, a positive treatment effect of intratendinous injections of steroid in Achilles tendonitis (AT) has been described. Our aim was to test the localization and distribution of the injected steroid in both healthy (animal) tendons and in diseased human Achilles tendons. Four pig tendons were injected in vivo and harvested. The harvested tendons were placed in 0.2 Tesla MRI scanner, in order to select the optimal MRI sequences for tracking and localizing the bolus injection. Three patients with AT were treated with intratendinous steroid injection. Injections were placed in the pathologic areas of the tendon guided by ultrasound (US). MRI and US were performed at baseline and again immediately and 60 minutes after injection. A final follow-up MRI was performed 1 month after the injection. In the animal model, significant recoil of the injected substance was seen in all cases. In all three patients the injection was readily distributed within the tendon and no recoil through the injection channel was found. One-month follow-up showed a total regression of hyperaemia on US as well as regression of intratendinous oedema on MRI in all 3 patients. It is possible to demonstrate the distribution pattern of injected steroid in diseased Achilles tendons by MR-imaging. In contrast to the recoil experienced in the healthy tendon of the animal, the lack of recoil of the injected volume through the injection channel in the sick human tendon may be caused by a derangement of the fibre structure, which allows the extra volume to be distributed within the lesion. This indicates that the effect on AT of intra-tendinous injections of steroid is due to a local intra-tendinous action of the drug.