INTERPRETATION OF ULTRASOUND FINDINGS IN ROTATOR CUFF PATHOLOGY – IMPLICATIONS TO THE SHOULDER SURGEON

Abstract

Ultrasonography for rotator cuff disease is a cheap and non-invasive investigation. Our study investigates the tendon specific pathologies leading to misinterpretation of ultrasound findings and their implication for the surgical management.

On hundred and five consecutive patients who had an ultrasound scan by a single musculoskeletal radiologist and then underwent shoulder arthroscopy by a single shoulder surgeon for rotator cuff pathologies were included.

Surpraspinatus Tendon (SST): There was a sensitivity of 90%. The relatively low positive predictive value (76%) and specificity (42.5%) were influenced by a high number of false positives. This was a mixed group of 23 cases, in which ultrasonography had described either a full-thickness (FTT) or partial-thickness (PTT) tear when arthroscopy did not show any evidence for a cuff tear. Seven of these cases were described as FTT with dimensions less than 1 cm and in ten cases the radiologist described a “possible sub-centimetre tear”. Subscapularis Tendon (SSC): There was a specificity of 100%. The poor negative predictive value (78%) and sensitivity (26%) were caused by a high number of false negatives. Further analysis of the 20 “false negative” patients showed four FTT and sixteen PTT. All partial thickness tears involved the superior fibres of the subscapularis tendon.

Our results confirm that USG is a reliable investigation in larger full thickness tears, particularly of the superior rotator cuff (SST). The reliability is significantly reduced in sub-centimetre tears and partial thickness tears, particularly of the subscapularis tendon. Associated tendon pathologies like intra-tendinous calcifications and intra-substance tears make an accurate diagnosis even more difficult and add to the tendency to ‘over-diagnose’ tears of the rotator cuff with use of ultrasonography.

The shoulder surgeon should be aware of the potential misinterpretation of ultrasonography findings and be prepared to adjust the surgical procedure accordingly.