TO THE EDITOR:
I take issue with several parts of "Current Concepts Review. Subacromial Impingement Syndrome" (79-A: 1854—1868, Dec. 1997), by Bigliani and Levine. The first problem has to do with the concept of impingement. I agree with the designation of impingement as a syndrome, meaning a concurrence of symptoms or signs (I do not believe that it should be designated as a diagnosis, which the authors did not do), but problems arise in the discussion of the pathological findings. The authors' exemplary historical account ends with Neer's idea of three stages of impingement1. My concern is particularly with stage I, which is described as "edema and hemorrhage of the bursa and cuff and is typically found in patients who are less than twenty-five years old." Since the syndrome most frequently occurs in older individuals, in whom it is a chronic rather than an acute process, it is logical that stage I is a precursor to stage II or III, but is there evidence to support this? The authors should have discussed and perhaps criticized the evidence derived from magnetic resonance imaging, arthroscopy, and perhaps operative observation, but probably not histological findings. I wonder how many young individuals at risk for the syndrome were investigated with any of the four mentioned modalities within two or three weeks after the onset of symptoms.
My second concern is about the authors' depiction of etiology. In contrast to Neer's classification of etiology1, they classified the possible factors as primary intrinsic, primary extrinsic, and secondary. The secondary causes (such as neurological injury) were dismissed from consideration because they were not considered relevant to the focus of the article. I do not take issue with the proposition that impingement may develop due to causes in any of these groupings, but I do assert that the syndrome is a secondary phenomenon in most patients, and I have reservations about each of the groupings. For example, is not muscle weakness often secondary to pain and disuse? How well can the boundary between tolerable use and overuse be determined? How often does degenerative tendinopathy develop in young subjects? My main concern is with the fuzziness of the correlation between demonstrable pathological lesions and the syndrome.
Admittedly, the investigation of such an association is fraught with difficulties. For instance, overuse is difficult to quantify in, for example, professional tennis players and carpenters. The problem is how to reveal the frequency of the syndrome and of any one of the primary pathological conditions in well delineated groups of such individuals.
Finally, the article may be criticized for not emphasizing that treatment of the syndrome is only occasionally directed at the real primary tear. Rather, it is often directed at the impingement process, worthwhile as that treatment may be.
Jonathan Cohen, M.D.: Franciscan Children's Hospital and Rehabilitation Center, 30 Warren Street, Boston, Massachusetts 02135-3680
Dr. Bigliani and Dr. Levine reply:
Regarding Dr. Cohen's first question concerning the concept of impingement, we agree with the suggestion that we should have more information concerning the earlier stages of impingement. However, since this was a review article and not an original article, we were not able to find sufficient information in the literature to enable us to correlate findings on magnetic resonance imaging with operative observations in the early stages of impingement. We agree that more work needs to be done concerning the early stages of this disease, especially in athletes who perform overhead motion. Currently, we are studying a group of patients who have pain in the anterior-superior aspect of the shoulder due to impingement on the coracoacromial ligament. These individuals perform overhead activity and have specific clinical findings and findings on magnetic resonance imaging. However, we have not published these data, and we do not believe that they are suitable for presentation in The Journal of Bone and Joint Surgery.
In reference to Dr. Cohen's second question, once again this is very difficult to answer on the basis of the available literature. As well as possible, we differentiated the etiologies into primary and secondary groups. We share the concern that there is some confusion as to what is really primary and what is really secondary. However, we reviewed information in the currently available literature and reported those findings. Once again, this was not an original scientific paper but rather a Current Concepts Review, and this type of paper has limitations.
Louis U. Bigliani, M.D.; William N. Levine, M.D.: New York Orthopaedic Hospital Associates, Incorporated, Columbia-Presbyterian Medical Center, 161 Fort Washington Avenue, New York, N.Y. 10032