Intra-articular glenohumeral injections are commonly performed during the non-operative treatment of various shoulder conditions, including adhesive capsulitis, biceps tendinopathy, and glenohumeral arthritis. Studies have demonstrated superior accuracy of fluoroscopic- or ultrasound-guided injections compared with palpation-directed injections. However, the advantages of these injection techniques need to be carefully weighed against the disadvantages related to increased time and cost associated with additional imaging and to the ionizing radiation exposure associated with fluoroscopy.
Another application for intra-articular glenohumeral injection is the delivery of gadolinium contrast for magnetic resonance arthrography or MRA, which offers increased diagnostic accuracy compared with non-contrast MRI, especially for low-field scanners. This study reinforces the commonly held opinion that experienced providers can routinely perform an intra-articular glenohumeral injection without adjunctive imaging.
The study has some limitations, including the fact that all injections were performed by a single shoulder arthroscopist who is experienced in palpation-directed glenohumeral injections, so that the results may not extend to less experienced providers. It also remains difficult to reconcile the high accuracy reported in some studies, including this one, with the poor accuracy reported in others. What are the differences? Is it physician experience, patient body habitus, underlying diagnoses, or a combination of these and other factors altogether? In addition, although it is intuitively desirable to inject into the intended location, it may not make that much of a difference. Studies have shown that even injections into the subacromial space can have a desirable effect on intra- or peri-articular conditions, such as adhesive capsulitis.
Finally, the study raises some questions about the role of in-office MRA using a low field scanner. Although the authors tout the efficiency and cost savings associated with their MRA protocol, the superior image quality and diagnostic ability of high-field scanners often obviates the need for contrast enhancement. In addition, whereas an 89% success rate for in-office corticosteroid injections is likely high enough, the corresponding 11% failure rate may be too high for the injection of contrast, especially when it is critical for the overall diagnostic value of the MRA study. Consequently, any added efficiency and cost savings associated with low-field MRA needs to be weighed carefully against the relatively low image resolution, the added morbidity associated with the injection, and the indirect costs associated with obtaining additional studies when the low-field MRA is non-diagnostic or when adequate contrast is not placed intra-articularly.
Samer S. Hasan, MD, PhD
Mercy/Cincinnati Sports Medicine and Orthopaedic Center
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