To distinguish using shoulder sonography the different changes present in rheumatoid arthritis (RA), polymyalgia rheumatica (PMR), and periarticular disorders (PD) of soft tissue of the shoulder.
Ninety shoulders of patients with RA, 32 with PMR, 122 with PD, and 108 controls were studied sonographically, using a 7.5 MHz linear probe. The following structures were evaluated: long head of biceps tendon, supraspinatus, infraspinatus and subscapularis tendons, subacromial and subscapularis bursae, rotator cuff (thickness), calcifications, and glenohumeral and acromioclavicular joints. Statistical analysis was by Student's t test and chi-squared test.
Involvement of long head of biceps tendon (peritendinous fluid collection, changes of thickness, and/or echotexture) was significantly different between RA and PMR and between PD and PMR. Alterations in thickness and/or fibrillar pattern were evaluated in rotator cuff tendons: supraspinatus tendon was involved with significant differences between PD and both RA and PMR; the changes of subscapularis tendon were present, with significant differences between PD and both the other groups; the alterations of infraspinatus tendon were not statistically different between the 3 groups. Effusion within bursae was present, with significant differences only between RA and PD. The mean thickness of rotator cuff was significantly different between controls (6.2 mm) and both PD (5.3 mm) and RA (5.8 mm), and between PMR (6 mm) and PD. Evaluation of effusion within the glenohumeral joint (capsule-bone distance) showed significant differences between controls (2.4 mm) and both RA (4.2 mm) and PMR (4 mm), between RA and PD (2.6 mm), and between PMR and PD. Calcifications were present only in PD (21.3%) and RA (6.7%), with significant differences. Effusion within the acromioclavicular joint was present in RA (35.5%) and PD (20.5%), with significant differences.
Shoulder sonography showed involvement of all structures in RA, the prevalence of effusion in PMR, and involvement mainly of tendons in PD.