Where the Sound don’t Shine
Shoulder pain is the third most common presenting musculoskeletal complaint1. Clinicians are challenged by the variety of different shoulder pathologies that can present similarly, despite a good patient history and a battery of physical exam maneuvers. Consequently, imaging plays a critical role in the evaluation of shoulder pathology. Ultrasound (US) is a reliable imaging modality for evaluating shoulder pathology, especially in the context of rotator cuff tears, with a significant impact on the clinical management of shoulder pain2. Citing similar accuracies between US and magnetic resonance (MR) imaging, The Society of Radiologists in Ultrasound released a consensus statement with an imaging algorithmic approach to suspected rotator cuff tears, suggesting that US should be the first line imaging modality for the atraumatic, native painful shoulder in patients <40 years old that may be suspicious for rotator cuff abnormality3.
However, there are several shoulder pathologies that present similarly to rotator cuff tears that cannot be reliably evaluated with US. Per the American College of Radiology Appropriateness Criteria, radiographs should be the first-line imaging choice for any acute shoulder pain4. And despite similar accuracies between US and MR imaging for rotator cuff tears, MR imaging provides the best evaluation of internal derangement. We present a case series of shoulder pathologies initially evaluated by US at our institution, with subsequent diagnosis made on follow-up using a different modality.
US is a cost-efficient and accessible imaging modality for clinicians. Including the benefits conferred to the patient such as comfort and lack of radiation, the popularity of utilizing US in the evaluation of shoulder pathologies is unsurprising, especially in setting of presumed rotator cuff tears. Clinicians must be aware, however, of the litany of pathology that present similarly to rotator cuff tears, and of the limitations of ultrasound, particularly in evaluating bone pathology deep to the cortex and intra-articular pathology. First-line imaging for any acute shoulder appropriately remains plain film evaluation. MR may be pursued to further evaluate soft-tissue or marrow pathology, when a diagnosis of a rotator cuff tear is equivocal.