MR Imaging of Overuse Injuries of the Achilles Tendon

This study was conducted to illustrate and classify the abnormalities found on high-resolution MR imaging of symptomatic Achilles tendons in athletic adult patients. One hundred patients with 118 painful Achilles tendons were imaged with a 1.5-T magnet. The tendon, peritendinous tissues, tendon insertion, and musculotendinous junction were examined on MR imaging. Twenty-eight patients underwent surgery, and histopathologic samples were taken in 13. Long-term follow-up was performed, on average, 3.4 years after MR imaging. Of 118 painful Achilles tendons, abnormalities were detected in 111. These were in the tendon (n = 90), surrounding structures, or both. Fifty-four tendons had a focal area of increased intratendinous signal, best detected on axial high-resolution T1-weighted gradient-echo MR imaging. Histopathology confirmed abnormal tendon structure. Of the 21 surgically proven foci of tendinosis, 20 were revealed on MR imaging. At the level of the insertion, changes were found in the tendon in 15%, in the retrocalcaneal bursa in 19%, and in the calcaneal bone marrow in 8% of the studies. Abnormalities in peritendinous soft tissues were detected in 67%. More than one type of abnormality was found in 64% of the studies. Lesions in the Achilles tendon and in the peritendinous structures can have similar clinical presentation. MR imaging detects and characterizes these changes. A more specific diagnosis and prognosis can be made with the use of MR imaging than with clinical examination alone.