Incidence of gadolinium or fluid signal within surgically proven glenoid labral tears at MR arthrography

From Labral Tears to Bone Loss: Imaging the Spectrum of Shoulder Instability

Glenohumeral instability results from disruptions in dynamic and static stabilizers of the glenohumeral joint, leading to dislocation, subluxation, or chronic apprehension. Although anterior glenohumeral instability is the most common form, posterior instability represents a distinct and often underrecognized condition with unique biomechanical and clinical characteristics. Imaging plays a critical role in evaluating shoulder instability, guiding diagnosis, and informing treatment decisions. Radiographs, computed tomography, and magnetic resonance imaging help assess structural abnormalities, such as labral tears, capsuloligamentous injuries, and osseous defects. Advanced imaging techniques, such as three-dimensional computed tomography and zero echo time magnetic resonance imaging, offer improved assessment of bone loss; magnetic resonance arthrography enhances the detection of soft tissue pathology. This article offers a comprehensive review of the imaging spectrum of glenohumeral instability, covering labral pathology, capsuloligamentous injuries, and bone loss. It highlights the critical role of precise imaging assessment in guiding optimal management strategies for both anterior and posterior instability patterns.

Anterior Instability: What to Look for

Most first-time anterior glenohumeral dislocations occur as the result of trauma. Many patients suffer recurrent episodes of anterior shoulder instability (ASI). The anatomy and biomechanics of ASI is addressed, as is the pathophysiology of capsulolabral injury. The roles of imaging modalities are described, including computed tomography (CT) and MR imaging with the additional value of arthrography and specialized imaging positions. Advances in 3D CT and MR imaging particularly with respect to the quantification of humeral and glenoid bone loss is discussed. The concepts of engaging and nonengaging lesions as well as on-track and off-track lesions are examined.

A comparison of saline and gadolinium shoulder MR arthrography to arthroscopy

PURPOSE

Compare the diagnostic performance of saline and gadolinium shoulder magnetic resonance arthrograms (MRA) in the detection of labral and rotator cuff injury compared to arthroscopy.

MATERIALS AND METHODS

Consecutive patients who underwent a gadolinium or saline MRA followed by arthroscopy were retrospectively reviewed. The reports were reviewed for injuries. A chi square or Fisher's exact test was performed to compare the MRA and surgery. Kappa values were calculated to correlate diagnosis of tear between MRA and arthroscopy.

RESULTS

There were a total of 58 patients included, including 34 gadolinium arthrograms and 24 saline arthrograms. The accuracy of saline MRA was similar compared to gadolinium MRA in the diagnosis of tears of the supraspinatus (accuracy 0.88 vs 0.74, respectively) and infraspinatus (accuracy 0.88 vs 0.65, respectively) tendons and tears of the anterior/anterior inferior, posterior, and superior labrum, (accuracy 0.79 vs 0.76, 0.71 vs 0.62, and 0.58 vs 0.56), and saline vs gadolinium, respectively. Although there was a trend toward overall better saline MRA performance, a statistically significant difference in the accuracy to detect tears was only noted for the infraspinatus tendon. Interobserver agreement for rotator cuff tears was higher for saline than gadolinium MRA.

CONCLUSION

Saline MRA was accurate, with no significant differences compared gadolinium arthrograms in the diagnosis of labral and rotator cuff pathology. Given expense, and the potential additional information provided by fluid sensitive sequences over T1 fat-suppressed sequences, consideration should be given to using saline for shoulder MRAs.

LEVEL OF EVIDENCE

Level III, Retrospective Cohort Study.