Interobserver variation in sonography of the painful shoulder

This study was conducted as a prospective assessment of interobserver variability in the sonographic evaluation of the rotator cuff.

Three musculoskeletal radiologists who had different levels of scanning experience each performed shoulder sonography on 24 consecutive patients during 1 patient visit. The diagnostic criteria full-thickness rotator cuff tear, tendon calcification, tendinosis of the supraspinatus, subacromial fluid, subacromial synovial/bursal thickening, dynamic signs of impingement, and abnormality in the long head of biceps tendon were scored, with independent observers recording the data. Statistical analysis was performed using Cohen's kappa test, with significance assessed at p values of less than 0.05.

There was good agreement (kappa >0.60, p <0.01) between the experienced operators for full-thickness rotator cuff tear, tendon calcification, dynamic signs of impingement, and abnormality of the long head of biceps tendon. There was no significant agreement between the experienced operators and the less experienced operator in several categories, including (and importantly) full-thickness rotator cuff tears (kappa=0.18-0.21).

In experienced hands sonography of the rotator cuff is a reproducible diagnostic test, but agreement is poor when there is marked disparity between the operators' experience levels. Our findings suggest a need for a more clearly defined training curriculum for sonography of the shoulder in radiology training programs.