There were two false-positive studies. Both were of patients who had previously undergone a mini-open, deltoid-splitting, rotator cuff repair. One of the patients had a markedly limited range of motion due to adhesive capsulitis, and the other had an overreduced rotator cuff repair.
If the index procedure involved treatment of a shoulder with an intact rotator cuff, the sensitivity, specificity, and accuracy of the postoperative ultrasound were all 100%. If the index procedure included a rotator cuff repair, the sensitivity, specificity, and accuracy of the postoperative ultrasound were 90%, 79%, and 85%, respectively.
The accuracy with which a treating physician can determine the integrity of the rotator cuff can have important implications for the management of a shoulder that is painful postoperatively. Authors of numerous clinical studies have reported variable success with nonsurgical management of painful rotator cuff tears 6-12. In the setting of an intact rotator cuff, the surgeon and patient can be more confident of achieving success with nonoperative treatment, without the long-term risks of rotator cuff atrophy, progression of the rotator cuff tear, or development of rotator cuff-related degenerative changes.
Magnetic resonance imaging provides an anatomic picture, demonstrates the quality of rotator cuff muscles, and shows other intra-articular and extra-articular pathology. However, the diagnostic role of magnetic resonance imaging of a shoulder that has undergone surgical treatment is controversial, with reported accuracy rates ranging from 70% to 90% 13-16. Additionally, in patients who have undergone shoulder surgery, sutures, suture anchors, and/or osseous changes may alter signal intensities within the acromion, humeral head, and rotator cuff tissue, and these altered signals may be indistinguishable from those of an acute rotator cuff tear 13-16. This is of particular concern given the widespread use of suture anchors for rotator cuff repairs.
Prior to the introduction of magnetic resonance imaging, arthrography was the imaging method used mostfrequently to evaluate the integrity of the rotator cuff 17. Disadvantages of this technique included its invasive nature and its inability to localize or quantitate a rotator cuff tear. In addition, arthrography yielded a substantial number of false-positive results following rotator cuff repair because of a non-watertight closure 18.
There have been very few studies on the use of ultrasound to evaluate shoulders postoperatively 3. Ultrasound may be especially helpful in this setting as the image should not be affected by the presence of intraosseous hardware. The reported sensitivities and specificities of ultrasonography before and after surgery on the shoulder have ranged from 50% to 100% 2,3,19,20. However, investigators who reported that ultrasound had poor accuracy for the diagnosis of rotator cuff tears used ultrasound criteria that are no longer accepted, a scanning technique that has since been modified to improve visualization of the rotator cuff, and/or equipment that is now outdated. Recently, Teefey et al. 2 reported on 100 consecutive patients who had undergone shoulder ultrasound prior to arthroscopy. On the basis of modern ultrasound criteria, the imaging had 100% sensitivity, 85% specificity, and 96% accuracy for detecting full-thickness rotator cuff tears.
We also found ultrasound to be highly accurate for evaluating the integrity of the rotator cuff after operations on the shoulder. It is inexpensive, noninvasive, and well tolerated, and it can often be performed in a timely fashion with immediate results. Importantly, the image is not degraded by suture anchors. However, its usefulness is limited in patients with a severely restricted range of motion because the entire rotator cuff cannot be adequately visualized. Its accuracy in detecting small partial-thickness rotator cuff tears may also be limited.
One limitation of our study was its retrospective design. This limitation was reduced in part by the standardized documentation of the operative findings and the photographic record of the rotator cuff. Another limitation was the potential bias toward improved accuracy because the surgeon who performed the arthroscopy had knowledge of the findings of the preoperative physical examination and the ultrasound results; however, as the study was performed retrospectively, there was not necessarily a bias by the surgeon to verify the results of the ultrasound at the time of the surgery.
One other important consideration was our statistical treatment of partial-thickness rotator cuff tears. Given previous reports 2,13-16 of the relative inaccuracy of both magnetic resonance imaging and ultrasound in the detection of partial-thickness tears in shoulders without previous operative treatment, we thought that the emphasis in our study should be on full-thickness rotator cuff defects. Partial-thickness tears thus were classified on the basis of their clinical relevance. We thought that this would add more clinical practicality to our conclusions. For this reason, rotator cuffs with a small partial-thickness tear treated only with débridement were considered to be intact, and large partial-thickness tears that were thought clinically to require repair were considered to be the same as full-thickness tears.
In conclusion, our findings suggest that ultrasonography can be highly accurate in the evaluation of the rotator cuff in shoulders that have been treated operatively. The results are comparable with those reported for shoulders without prior operative treatment. The lack of image degradation in the presence of commonly used suture anchors suggests that this modality may compare favorably with magnetic resonance imaging for the evaluation of shoulders that have been treated operatively.
Investigation performed at the Shoulder and Elbow Service, Department of Orthopaedic Surgery,Washington University, Barnes-Jewish Hospital, St. Louis, Missouri
The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.
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