Ultrasound revealing subclinical enthesopathy at the greater trochanter level in patients with spondyloarthritis

This study was conducted to determine the prevalence of subclinical entheseal involvement at the greater trochanter level by ultrasound in patients with spondyloarthritis. Forty-six patients with spondyloarthritis and 46 healthy age- and sex-matched controls were studied. All patients with no clinical evidence of enthesopathy at the greater trochanter underwent an ultrasound examination. The following three entheses were scanned bilaterally: anterior insertion of gluteus minimus, anterior insertion of gluteus medius, and posterior insertion of gluteus medius. Ultrasound findings of enthesopathy were thickening, calcifications, bone erosions, enthesophytes, bursitis, and power Doppler signal. A total of 276 entheses were evaluated in spondyloarthritis patients. In 112 out of 276 (40.5%), grayscale ultrasound found enthesopathy. The enthesis with the highest number of signs of enthesopathy was the anterior insertion of gluteus medius (46/276) (16%), followed by posterior insertion of gluteus medius (37/276) (13.4%) and anterior insertion of gluteus minimus (29/276) (10.5%). In the healthy population, ultrasound found entesopathy in 80 out of 276 (29%) entheseal sites (p < 0.0001). Posterior insertion of gluteus medius enthesis was the more frequently involved (34/276) (12.3%), followed by anterior insertion of gluteus medius (24/276) (8.6%) and anterior insertion of gluteus minimus (22/276) (7.9%). Power Doppler was found more frequently in patients with spondyloarthritis compared with healthy controls (1% vs 0%). Our results show a higher prevalence of subclinical enthesopathy at the greater trochanter level in patients with spondyloarthritis than in age- and sex-matched healthy controls.