MR Imaging of Asymptomatic Individuals After Rotator Cuff Repair

Abstract & Commentary

Synopsis: MR findings should be interpreted with caution and correlated with symptoms in the postoperative rotator cuff.

Source: Spielmann AL, et al. Shoulder after rotator cuff repair: MR imaging findings in asymptomatic individuals—Initial experience. Radiology 1999;213:705-708.

Mri has assumed an important role in evaluation of the postoperative rotator cuff. Criteria for retear are well established. Spielmann and colleagues have gone one step further to show the MR appearance of the rotator cuff in postoperative cuff repair patients who are asymptomatic.

Fifteen subjects with a mean age of 60 years who were considered surgical successes following rotator cuff repair were included in the study. All participants had good to excellent clinical scores according to the Constant scale. Routine MR imaging was performed on both the postoperative as well as the contralateral shoulder of each patient using a 1.5T scanner (Horizon Echo-Speed; General Electric Medical Systems, Milwaukee, WI). An oblique coronal fast spin-echo fat-suppressed T2-weighted MR sequence was included in every study to provide optimal demonstration of rotator cuff abnormalities.

Three (10%) of 30 supraspinatus and infraspinatus tendons had normal signal intensity and 16 (53%) had mildly increased signal intensity on FSE T2-W images with fat suppression. This finding was found to be compatible with tendonitis/tendonosis. There were three partial and four complete tears of the supraspinatus tendon and two partial and two complete tears of the infraspinatus tendon. Other findings included subacromial-subdeltoid effusion (n = 10), joint effusions (n = 5), and bone marrow edema (n = 6).

Spielmann et al conclude that in asymptomatic postoperative rotator cuffs, signal intensity changes consistent with tendonitis/tendonosis are common and that clinically "silent" partial and complete rotator cuff tears may also be seen. These findings should be interpreted with caution and correlated with symptoms and clinical results.

Comment by Lynne S. Steinbach, MD

While MRI is well established for preoperative assessment of the rotator cuff, less is known about MR evaluation of the postoperative rotator cuff. In general, criteria for an intact rotator cuff include low to intermediate signal intensity within the tendon on all MR imaging sequences. Several studies have found high sensitivity and specificity for postoperative diagnosis of a full-thickness rotator cuff tear in symptomatic patients.1-3 Owen et al demonstrated an 86% sensitivity, 92% specificity, and a 90% accuracy for the MR diagnosis of a residual or recurrent full-thickness rotator cuff tear following repair.1 Magee et al reported similar results with an 84% sensitivity and 91% specificity.2

This study is the first of its kind to assess the MRI appearance of the successfully repaired rotator cuff in an asymptomatic population. Although the findings are based on a small population of asymptomatic individuals, there are some important observations that should affect the way that radiologists interpret abnormal findings in these postoperative shoulders. It is known that partial- and full-thickness rotator cuff tears can be asymptomatic.4 Why shouldn’t the postoperative population have the same findings as the general population? The situation is similar to the lumbar spine where many "abnormalities," such as disk bulges and protrusions, are seen in asymptomatic individuals.

As Spielmann et al state, the study was limited by the small number of subjects and further investigation of a large group of asymptomatic individuals, perhaps through a multicenter study, would be warranted to confirm these results. The inability to obtain surgical confirmation was another limitation of this study that could not be avoided since asymptomatic individuals do not need diagnostic or therapeutic surgical confirmation of these findings. The major point of this study is that imaging abnormalities should always be correlated with the clinical scenario in order to determine their significance.

References

1. Owen RS, et al. Shoulder after surgery: MR imaging with surgical validation. Radiology 1993;186:443-447.

2. Magee TH, et al. MR imaging of the shoulder after surgery. AJR Am J Roentgenol 1997;168:925-928.

3. Gaenslen ES, et al. Magnetic resonance imaging for evaluation of failed repairs of the rotator cuff. J Bone Joint Surg 1996;78:1391-1396.

4. Sher JS, et al. Abnormal findings on magnetic resonance images of asymptomatic shoulders. J Bone Joint Surg 1995;77:10-15.