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Saturday, February 26, 2005

Avoid surgery based on MRI interpretation of partial tears of rotator cuff

Using magnetic resonance imaging (MRI) to diagnose complete tears of the rotator cuff is both acceptable and accurate, but the diagnosis of a partial tear on MRI should not be used as an indication for surgery, according to the presenters for Paper 334.

Although numerous studies have shown reasonable sensitivity and specificity with the diagnosis of complete tears of the rotator cuff, MRI diagnosis of partial tears remains more problematic. Researchers studied of 80 consecutive patients whose MRI scans were interpreted as either "partial rotator cuff tear" or "possible partial rotator cuff tears" by the reviewing radiologist.

Patients were followed for a 12-month period. Physical examination and presence or absence of a positive Lidocaine impingement test was documented. Eighteen patients also had an arthrogram. All patients then underwent arthroscopic evaluation of the shoulder, documented by videotape, and were treated based on the arthroscopic findings.

Only 65 percent of the scans could be interpreted definitively. Correlation of MRI reports of partial tear to observed arthroscopic findings was poor. Only 17 of 80 patients were correctly diagnosed, resulting in a false positive rating of 78 percent. In 38 cases, there was no tear, and in 25 cases, there was a complete tear. Using Neer's criteria, 10 shoulders with the MRI diagnosis of a partial rotator cuff tear could not even be diagnosed with impingement.

An orthopaedic review of the scans found that isolated radiologic interpretation of partial thickness rotator cuff tear was based on non-specific increased signal on T1 and T2 images is not an indication for surgery. A more accurate assessment of surgically treatable rotator cuff tears can be obtained by correlating the physical examination with the presence or absence of a positive Lidocaine impingement test.

"MRI scanning continues to be a valuable tool in the armamentarium of the orthopaedic surgeon treating shoulders…[but it is] not designed to replace careful history, physical examination, and appropriate differential injection for diagnosis," concluded the presenter. "The diagnosis of partial rotator cuff tears appears to remain largely a clinical diagnosis, confirmed by arthorscopic exploration."

The presenter was Stephen C. Weber, MD, of Sacramento, Calif., who has served as a consultant for Depuy and Arthrex.

Arthroscopic picture of a partial rotator cuff tear

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