Table 3.

OMERACT definitions of elementary lesions of enthesitis upon ultrasound examinations.

Elementary Lesion	Definition
Hypoechogenicity	Lack of the homogeneous fibrillar pattern in the enthesis (<2 mm from the cortical bone) with loss of the tightly packed echogenic lines after correcting for anisotropy.
Increased thickness at enthesis	Increased thickness of the tendon insertion into the bone (<2 mm from the cortical bone) as compared with the body of tendon, with or without blurring of the tendon margins.
Erosions	Cortical break with a step-down contour defect, seen in two perpendicular planes, at the insertion of the enthesis.
Calcifications	Hyperechoic foci, with or without acoustic shadow, detected at the enthesis (<2 mm from the cortical bone).
Enthesophytes	Enthesophyte was defined as a step-up of bony prominence, seen in two perpendicular planes at the end of the bone contour of the enthesis.
Doppler signal at insertion	Doppler signal seen at bone insertion (<2 mm from the cortical bone), different from reflecting surface artefact or nutrition vessel signal, with or without cortical irregularities, erosions, or enthesophytes.