Background: To evaluate the diagnostic performance of magnetic resonance arthrography (MR-A) of the shoulder in the diagnosis of rotator cuff tears involving the humeral insertion of the supraspinatus and infraspinatus tendon (footprint), using arthroscopy as the reference standard.
Materials and methods: The study population included 90 consecutive patients with history and clinical diagnosis of instability of the shoulder, rotator cuff tear or posterosuperior glenoid impingement. A total of 108 MR arthrograms were performed, since 18 patients had undergone a bilateral procedure. Arthroscopy, which was performed within 45 days after MR-A, was used as the reference standard. Sensitivity, specificity, accuracy, positive and negative predictive values were then calculated.
Results: Magnetic resonance arthrography showed a sensitivity of 92 % and a specificity of 78 % for the overall detection of tears involving the rotator cuff footprint. The diagnostic accuracy was 90 %, and the positive and negative predictive values were 95 and 64 %, respectively. Ten lesions were non-classifiable on surgery, of which eight were non-classifiable on MR-A also.
Conclusions: Magnetic resonance arthrography is extremely accurate for the detection and classification of rotator cuff footprint tears. Most of these lesions are articular-sided (partial articular-sided supraspinatus tendon avulsion lesions) with predominance in younger patients and concealed type of tear (concealed interstitial delamination lesions).