Ultrasound pathology of the entheses in an age and gender stratified sample of healthy adult subjects: a prospective cross-sectional frequency study

Ultrasound (US) examination of the entheses is increasingly used. However, little is known about US findings in the entheses in asymptomatic persons. The aim of this study was to investigate the appearance of US signs in the enthuses of the lower limb in asymptomatic subjects. We recruited 64 subjects, eight women and eight men whose ages covered four decades, from 20 to 60 years. None had tendon or joint disease in the lower limbs. Participants were examined by a rheumatologist and blood samples were collected to rule out enthesis pathology. The enthesis of the dominant leg were examined with grey-scale and Doppler US to evaluate increased thickness, changed structure, enthesophytes/calcifications, erosions, and colour Doppler signal. Ultrasound examination of 320 entheses was made. At enthesis level, elementary lesions were seen at 73 (22.8%) sites, at subject-level 47 (73.4%) persons showed elementary lesions, in 27 (57%) only one enthesis was affected. Doppler activity was seen in four sites, three at the quadriceps insertion. Most common US elementary lesion was enthesophytes at the Achilles and quadriceps tendon insertion. A tendency towards more elementary lesions was seen in men, and a slight increase was seen with increasing age, however, not statistically significance. Our findings suggest that US can be used to diagnose/examine subjects in adulthood for pathological changes in the entheses; however, caution should be taken regarding enthesophytes of the quadriceps and Achilles tendon.