Magnetic resonance imaging of the shoulder. Sensitivity, specificity, and predictive value

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1 This is an enhanced PDF from The Journal of Bone and Joint Surgery The PDF of the article you requested follows this cover page. Magnetic resonance imaging of the shoulder. Sensitivity, specificity, and predictive value JP Iannotti, MB Zlatkin, JL Esterhai, HY Kressel, MK Dalinka and KP Spindler J Bone Joint Surg Am. 1991;73: This information is current as of November 30, 2010 Reprints and Permissions Publisher Information Click here to order reprints or request permission to use material from this article, or locate the article citation on jbjs.org and click on the [Reprints and Permissions] link. The Journal of Bone and Joint Surgery 20 Pickering Street, Needham, MA

2 Copyright 1991 by The Journal of Bone and Joins Surgery. Incorporated Magnetic Resonance Imaging of the Shoulder SENSITIVITY, SPECIFICITY, AND PREDICTIVE VALUE* BY JOSEPH P. IANNOTTI, M.D., PH.D.t, MICHAEL B. ZLATKIN, M.D., JOHN L. ESTERHAI, M.D.t, HERBERT Y. KRESSEL, M.D.t, MURRAY K. DALINKA, M.D.t, AND KURT P. SPINDLER, M.D.t, PHILADELPHIA, PENNSYLVANIA From the Departments of Orthopaedic Surgery and Radiology. University ofpennsylvania, School ofmedicine, Philadelphia ABSTRACT: The sensitivity, specificity, and predictive value of magnetic resonance imaging in the diagnosis of lesions of the rotator cuff, glenohumeral capsule, and glenoid labrum were evaluated in ninety-one patients and fifteen asymptomatic volunteers. Magnetic resonance imaging demonstrated 100 per cent sensitivity and 95 per cent specificity in the diagnosis of complete tears, and it consistently predicted the size of the tear of the rotator cuff. There was a definite correlation between atrophy of the supraspinatus muscle and the size of a complete, chronic tear of the rotator cuff. The sensitivity and specificity of magnetic resonance imaging in the differentiation of tendinitis from degeneration of the cuff were 82 and 85 per cent, and in the differentiation of a normal tendon from one affected by tendinitis with signs of impingement the sensitivity and specificity were 93 and 87 per cent. The formation of spurs around the acromion and acromioclavicular joint correlated highly with increased age of the patient and with chronic disease of the rotator cuff. The sensitivity and specificity of magnetic resonance imaging in the diagnosis of labral tears associated with glenohumeral instability were 88 and 93 per cent. The study showed that high-resolution magneticresonance imaging is an excellent non-invasive tool in the diagnosis of lesions of the rotator cuff and glenohumeral instability. Pain and dysfunction of the shoulder are often caused by lesions of the rotator cuff or of the glenohumeral capsule and labrum. The spectrum of lesions of the rotator cuff ranges from chronic tendinitis to complete rupture. Imaging modalities that are currently used to evaluate such lesions include ultrasonography 1.21, single and double-contrast arthrography subacromial bursography 933, and arthroscopy of the shoulde?. The ability of each of these techniques to accurately demonstrate the different diseases that affect the rotator cuff is limited. Computed arthroto- B No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject ofthis article. No funds were received in support of this study. t University ofpennsylvania, 3400 Spruce Street, Philadelphia, Pennsylvania Please address requests for reprints to Dr. lannotti. t Department ofradiology, Memorial Hospital, 3501 Johnson Street, Hollywood, florida mography has been used to assess the capsular mechanism and the glenoid labrum in patients who have glenohumeral instability Ultrasonography has not been very useful in visualizing the labrum. To our knowledge, most studies that have shown magnetic resonance imaging to be useful in the diagnosis of lesions of the rotator cuff and of the glenohumeral capsule and labrum have been performed on small groups of patients This study ofa larger series was designed to evaluate the efficacy of high-resolution magnetic-resonance imaging in the diagnosis of lesions of the rotator cuff and of the glenohumeral capsule and labrum. Study Population Materials and Methods One hundred and twenty-seven magnetic resonance images were evaluated for lesions of the rotator cuff or of the glenohumeral capsule and glenoid labrum in ninety-one patients who were then operated on for the first time and in fifteen asymptomatic volunteers (Fig. 1). In seventy-three shoulders, the rotator cuff was inspected at operation, and in thirty-nine shoulders, the glenohumeral capsule and the glenoid labrum were inspected. Sixty-four images of the rotator cuff were made for patients who had symptoms related to the rotator cuff; fifteen, for asymptomatic volunteers; and nine, for patients who had a lesion of the labrum, had no history of dislocation of the shoulder, and had had arthroscopy of both the glenohumeral joint and the subacromial bursa. At operation, thirty-three ofthe images were found to be associated with a complete tear of the rotator cuff; thirty-one, with tendinitis or with degeneration or a partial tear of the rotator cuff; and nine, with a labral tear without dislocation. Nine scans of the rotator cuff of patients who had a primary diagnosis of a labral lesion were included because, although the rotator cuff was not explored by open operation, it had been evaluated adequately with both magnetic resonance imaging and arthroscopy. Tendinitis was defined as an area of hyperemia on the undersurface of the tendon, as seen arthroscopically, or as thickening and hypertrophy of the bursae on the acromial side of the tendon, as seen at open acromioplasty. Degeneration or a partial tear of the rotator cuff was diagnosed when fraying and fibrillation of the tendon were observed through the arthroscope. Impingement syndrome was di- VOL. 73-A, NO. I, JANUARY

3 18 J. P. IANNOTTI ET AL. 15 asymptomatic volunteers 127 MRI Diagnoses (106 patients) diagnoses rotator cuff study (88 MRI diagnoses) diagnoses (91 patients) 39 capsule-labrum capsule-labruzn study diagnoses (39 MRI diagnoses) Study FIG. 1 population. agnosed when pain that was localized to the anterolateral aspect of the shoulder occurred with overhead activities. The symptoms were relieved within five minutes after lidocaine was injected into the subacromial space. No patient who had signs of impingement had pain in the neck or symptoms distal to the elbow. The impingement syndrome was not relieved by well supervised therapy that included a standardized exercise program and the avoidance of activities that precipitated the symptoms. It was also not relieved by anti-inflammatory medication or by injections of cortisone into the subacromial space. Of the thirty-nine shoulders in which magnetic resonance images visualized the labrum and the capsule, nineteen were seen to have a torn labrum at operation; six, a degenerated labrum; and fourteen, a normal labrum. Twenty-five of these studies were of patients in whom the primary diagnosis was a lesion of the labrum and capsule, and fourteen were of patients who had symptoms of impingement and an intact rotator cuff. Patients in whom the symptoms were due to impingement were included because the labrum and capsule had been adequately evaluated with imaging and arthroscopy. Clinical Evaluation Thirty-three complete tears of the rotator cuff were treated with an open Neer-type acromioplasty, excision of the coracoacromial ligament, removal of spurs from the acromioclavicular joint, and repair of the cuff through an anterosuperior approach During the operation, the maximum anterior-posterior and medial-lateral dimensions of the tears were measured and photographed. Care was taken to remove only bursal tissue so that the measurements would not be altered. The arm was placed in the same position as was used for the imaging studies (neutral abduction and rotation). The surface area of the tear was calculated in square centimeters, and the shape and size of the tear were drawn on a standardized template. Of the thirty-three tears of the rotator cuff, thirty were chronic and three were acute. A chronic tear was diagnosed when the patient had a minor injury (incurred during lifting or a simple fall) and symptoms suggestive of impingement. The acute tears were associated with high-velocity trauma - two were the result of a motor-vehicle accident and one occurred when the patient was thrown from a horse - and there was no history of pre-existing pain in the shoulder. Of the thirty-one shoulders that were affected by an impingement syndrome but in which the tendons of the rotator cuff were intact, eighteen were evaluated arthroscopically. In nine of these eighteen shoulders, an open acromioplasty was done subsequently, and, in the other nine, an arth.roscopic acromioplasty was done. In this subgroup, the arthroscopic finding of either degeneration or a partial tear of the cuff as opposed to inflammation of the cuff alone (tendinitis) could be correlated with the diagnosis that had been made on the magnetic resonance images, and the correlation could be evaluated statistically. In thirteen shoulders, an arthroscopic evaluation was not done, but an open acromioplasty had been performed as the initial procedure. An operation was done on all thirty-nine shoulders in which the capsule had been evaluated. In twenty-two of these shoulders, only arthroscopy was done, and in ten, only an open operation was performed. The open operations consisted of a Bankart procedure in four shoulders and a Bristow procedure in six. In the remaining seven shoulders, both arthroscopy and an open operation were done, and the open operations consisted of a Bristow procedure in one shoulder, a Bankart procedure in two, and capsular shift in four. A complete physical examination of the shoulder was carried out while the patient was under anesthesia. For four shoulders, the diagnosis was multidirectional instability, with a positive sulcus sign, anterior translation of more than 50 per cent of the diameter of the humeral head, and posterior translation of 50 to 100 per cent of the diameter of the humeral head. All four shoulders had signs ofligamentous laxity. Fourteen shoulders had unidirectional (anterior) instability, with anterior translation of at least 25 to 50 per cent of the diameter of the humeral head when the arm was in 90 degrees of abduction and 90 degrees of external rotation. In thirteen of these fourteen shoulders, glenohumeral dislocation had been documented radiographically; the fourteenth shoulder had multiple episodes of glenohumeral subluxation. There were seven labral tears without instability in patients who had pain in the anterior aspect of the shoulder in the so-called cocked-arm position. The pain was usually ThE JOURNAL OF BONE AND JOINT SURGERY

4 MAGNETIC RESONANCE IMAGING OF THE SHOULDER 19 associated with a clicking sensation. Examination with the patient under anesthesia did not demonstrate abnormal anterior translation of the glenohumeral joint. Separation of the anteroinfenor part of the glenohumeral ligament-glenoid labrum complex from the glenoid rim was diagnosed as a Bankart lesions. The other type of tear that was seen was separation of the anterosuperior part of the glenoid labrum from the glenoid rim, with vascularization or hemorrhage and fraying of the labrum. Separation of the anterosuperior part of the labrum, without degenerative changes, was diagnosed as a normal variant (a Type- I cleft labrum)4. The presence or absence of a posterior defect of the humeral head (a Hill-Sachs lesion) was noted during the arthroscopic evaluation. Magnetic Resonance Imaging Technique and Diagnostic Criteria A 1.5-tesla whole-body magnetic-resonance scanner (General Electric, Milwaukee, Wisconsin) was used. The technique was relatively standard throughout the study, except for changes that were related to improvements in the technology involving the surface coil and the imaging software. Two fourteen-centimeter (five and one-half-inch) round general-purpose receive-only surface coils were used, one anterior and one posterior to the affected shoulder. The coils were stabilized in an adjustable plastic holder that had been designed for that purpose. The coil cables were attached to a BNC T connector to enable insertion into the surface-coil port in the head coil. In this configuration, the signal that is obtained from the two coils is additive and produces a homogeneous signal intensity throughout the imaging volume. For fifteen shoulders, the study involved the use of a prototype single-loop (17.8-centimeter [seveninchi) anterior shoulder coil that had been provided by the manufacturer (General Electric). For the patients in whom a lesion of the rotator cuff was suspected, the magnetic resonance studies included axial and sagittal oblique images, made with a short repetition time (800 milliseconds) and a short echo time (twenty milliseconds), and coronal oblique images, made with a short repetition time (800 to 1000 milliseconds) and a short echo time (twenty milliseconds) and with a long repetition time (2500 milliseconds) and a long echo time (twenty to seventy milliseconds). Oblique imaging was not done on the first eight shoulders because they were examined before software for such imaging was available The fields of view ranged from fourteen to twenty centimeters. Two excitations were used, and the matrix size was 256 by 128 in all studies. The slice thickness was four to five millimeters, with a onemillimeter interslice gap for the axial and sagittal oblique images and for the coronal oblique images that were made with a long repetition time and echo time. A three-millimeter interleaved sequence was used for the coronal oblique images that were made with a short repetition time and echo time. For the patients who were evaluated for a possible lesion ofthe glenoid labrum and glenohumeral capsule, axial images were made with a short repetition time and echo time, as a three-millimeter interleaved sequence. The sagittal oblique images were omitted, and an axial sequence was made with a long repetition time and echo time and a four or five-millimeter slice thickness. For the last five shoulders that had a glenohumeral lesion to be examined, instead of the axial sequence with a short repetition time and echo time, slice-interleaved gradient echo images with a repetition time of400 milliseconds, an echo time of fifteen milliseconds, and a flip angle of 70 degrees were made in the axial plane. The magnetic resonance images of thirty-two shoulders in which a lesion of the rotator cuff was operated on and those of the normal volunteers were reviewed retrospectively by three radiologists (M. B. Z., M. K. D., and H. Y. K.). The examiners were not provided with any dinical data. The remaining magnetic-resonance images were reviewed by only one of us (M. B. Z.). The diagnosis was based on the appearance of the rotator-cuff tendons and the presence or absence of signs denoting involvement of the subacromial-subdeltoid bursa and the subacromial-subdeltoid fat plane (Table 1)3839. This penbursal fat plane, an area of high signal intensity on Ti-weighted images, is found distal to the acromion and the deltoid muscle and proximal to the rotator-cuff tendons In the presence of a tear of the rotator cuff, this area of high signal intensity may be obliterated on Ti and proton density-weighted images. On T2-weighted images, signal intensity consistent with that of fluid may be seen in the bursa itself39. The rotator-cuff tendons were evaluated and graded. Grade 0 meant that the signal and morphological findings for the tendons were normal and Grade 1, that signal intensity was increased but the morphological findings were TABLE SCORING SYSTEM FOR THE STATUS OF THE ROTATOR Cure AS SEEN ON MAGNETIC RESONANCE IMAGING Category and Status Score (Points) I Maximum Score for Category (Points) Tendon 3 Intact; normal 0 Discontinuous (if yes, go to 3 subdeltoid fat plane) Abnormal signal intensity I in tendon Abnormal morphology of tendon 1 Subdeltoid fat plane I Present 0 Absent 1 Subdeltoid fluid I None 0 Present 1 Subacromial fat plane 1 Present 0 Absent 1 Subacromial fluid 1 None 0 Present I Maximum total score 7 VOL. 73-A, NO. I, JANUARY 1991

5 20 J. P. IANNOTTI ET AL. FIG. 2 FIG. 3 Fig. 2: Mid-plane coronal oblique image (repetition time, 800 milliseconds; echo time, twenty milliseconds) of a normal shoulder, illustrating the intermediate signal intensity of the supraspinatus muscle (SSM) and the homogeneous signal void of the supraspinatus tendon (black arrows). The subacromial-subdeltoid peribursal fat plane, which has a high signal intensity, is also clearly defined (open arrows). Fig. 3: Anterior coronal oblique image (repetition time, 800 milliseconds; echo time, twenty milliseconds) showing tendinitis. Diffuse high signal intensity is seen in the distal portion of the supraspinatus tendon (black arrow). The tendon is neither thinned nor irregular. The peribursal fat plane is normal. A small acromial spur is present anteriorly (open arrow), and the capsule of the acromioclavicular joint is mildly hypertrophic (white arrow). normal. Grade 2 was assigned when both the signal and the morphological findings were abnormal. (Grade 2 was later subdivided into Grades 2A and 2B, depending on how much the morphological characteristics of the tendon had been altered.) Abnormal morphological findings were defined as obvious thinning or irregularity of the tendons. Grade 3 meant that the tendons had a definite area of discontinuity or a gap in the normal signal void. The area of discontinuity is typically seen as an area of increased signal intensity on T2-weighted images. The rotator cuff was classified as normal (Grade 0) when the signal and morphological findings were normal and the subacromial-subdeltoid fat plane was intact (Fig. 2). The tendon was considered to be intact but affected by tendinitis (Grade 1) when the signal intensity was increased but the morphological characteristics were normal, as seen on proton density-weighted sequences with a short repetition time and echo time (Fig. 3). Increased signal intensity and some alteration ofthe morphological findings in the presence of an intact subacromial-subdeltoid fat plane were suggestive of a degenerated tendon (Grade 2). When the subacromial-subdeltoid fat plane was disrupted, the cuff was considered to be partially torn (Fig. 4). A complete tear of the rotator cuff was diagnosed when a Grade-2 or Grade-3 tendon was associated with loss of the overlying high signal intensity of the subacromial-subdeltoid fat plane on Tiweighted (short repetition time and echo time) or proton density-weighted images and when fluid in the subacromialsubdeltoid bursa was seen on T2-weighted images (long repetition time and echo time) (Figs. 5-A through 6-C). When a complete tear was diagnosed, its size in the medial-lateral and anterior-posterior planes was recorded, and the cross-sectional area was calculated. The exact location of the tear, the particular tendons that were involved, FIG. 4 Mid-plane coronal oblique image (repetition time, 800 milliseconds; echo time, twenty milliseconds) showing degeneration or a partial tear of the rotator cuff. The signal intensity of the supraspinatus tendon is increased, and the tendon is substantially thinned (black arrows). The signal is decreased in the peribursal fat plane overlying the abnormal portion of the tendon (open arrows). On the images that were made with a long repetition time and echo time (not shown), the intensity of the signal of the tendon was not increased further, and no fluid was seen in the subacromial-subdeltoid bursa. ThE JOURNAL OF BONE AND JOINT SURGERY

6 MAGNETIC RESONANCE IMAGING OF THE SHOULDER 21 FIG. 5-A FIG. 5-B Figs. 5-A and 5-B: Mid-plane coronal oblique images showing a small tear of the cuff. Fig. 5-A: On an image made with a short repetition time and echo time (800 and twenty milliseconds), a small focus of discontinuity is seen in the supraspinatus tendon (arrows). The peribursal fat plane is lost. Fig. 5-B: On an image made with a long repetition time and echo time (2500 and seventy milliseconds), the intensity of the signal within the small region of discontinuity in the tendon is increased further (black arrow). High-signal-intensity fluid is seen in the subacromial-subdeltoid bursa (white arrows). the presence of atrophy of the muscular portion of the rotator cuff, and degenerative changes such as subacromial spurs (Fig. 6-A) were all noted. Any impingement of these osseous spurs on the muscle-tendon complex was also recorded. In an attempt to evaluate the objectivity and reproducibility of the interpretation of the magnetic resonance images, a scoring system was developed, based on the appearance of the tendons and the status of the subacromial-subdeltoid fat plane and bursa (Table I). This scoring system was not used to make the final radiographic diagnosis; it was used retrospectively. The images for ten shoulders were evaluated retrospectively for abnormalities of the labrum and capsule. All were evaluated for the presence of a Hill-Sach lesion and osseous defects of the glenoid margin (Fig. 7). When a glenoid labrum is normal, a homogeneous, low signal intensity is seen on all pulse sequences 4 7#{176} , and the anterior part of the labrum is usually triangular in outlin& (Fig. 8). When an increased signal intensity was seen within the labrum but not extending to the surface of the labrum, on density-weighted images that were made with a short repetition time and echo time, the labrum was classified as Type 1, which meant that there was internal degeneration without evidence of a tear. When the signal was normal but the labrum appeared blunted or frayed, the labrum was classified as Type 2. A labrum was considered to be Type 3 if images that had been made with a short repetition time and echo time and density-weighted images showed an abnormal signal, extending to the surface of the labrum, that was thought to indicate a labral tear (Fig. 9). Increased signal intensity, similar to that of fluid, within the labrum or extending to its surface, as seen on images made with a long repetition time and echo time, was also considered indicative of a Type-3 (torn) labrum. A Type-4 labrum had the combined features of Types 2 and 3. The appearance of the capsule and associated glenohumeral ligaments and the type of insertion (Type 1, 2, or 3), as described in the literature, were recorded, as was the presence of any abnormal signal in the marrow ofthe glenoid (Figs. 10 and 1 l) The type of the capsule, as determined with magnetic resonance imaging, could not be directly correlated with the operative findings because of differences in the way the patients were positioned and because of the use of saline solution to distend the joint during arthroscopy. Definition of Terms Sensitivity is defined as the percentage of times that the test is positive in patients who are known to have the specific pathological entity. Sensitivity is calculated by dividing the number of true-positive results by the total number of true-positive and false-negative results. Specificity is defined as the percentage of times that the test is negative in patients who are known not to have the pathological entity. Specificity is calculated by dividing the number of true-negative results by the total number of true-negative and false-positive results. The predictive value of a positive test is defined as the likelihood that a patient for whom the test is positive has the lesion. It is calculated by dividing the number of truepositive results by the total number of true-positive and false-positive results. The predictive value of a negative test is defined as the likelihood that a patient for whom the study is negative does not have the lesion. It is calculated by dividing the number of true-negative results by the total number of true-negative and false-negative results. VOL. 73-A, NO. I, JANUARY 1991

7 22 J. P. IANNOTTI ET AL. FIG. 6-A Figs. 6-A, 6-B, and 6-C: Mid-plane coronal oblique images showing a large tear of the cuff. Fig. 6-A: On an image made with a short repetition time and echo time (800 and twenty milliseconds), the supraspinatus tendon is seen to be completely disrupted and retracted to the level of the acromioclavicular joint (white arrow). The edges of the cuff are irregular. Substantial muscle atrophy is present (open arrows), and there are considerable degenerative changes of the acromioclavicular joint (black arrow). Fig. 6-B: On an image made with a long repetition time and echo time (2500 and seventy milliseconds), the tear of the cuff is outlined further by the presence of high-signal-intensity fluid (black arrows). The edges of the cuff are irregular, and there is a large amount of fluid in the bursa (open arrows). Note the fluid in the sheath of the biceps tendon and in the joint space (white arrow). Rotator Cuff Complete Tears Results The thirty-three complete tears of the rotator cuff that were seen at operation had been diagnosed as complete tears preoperatively with the help of magnetic resonance images (Table II). The average score was 6.5 ± 0.8 points, as determined on the images. Seven of the tears were small (less than two centimeters in diameter), ten were moderate in size (two to four centimeters), and fourteen were large (more than five centimeters). The size of all of the large tears had been assessed accurately on the magnetic resonance images, except for two that had been assessed as being moderate in size. The correlation between the operative measurement of the size of the tear and the measurement on the magnetic resonance images was excellent (r = 0.96) (Fig. 12). A finding of atrophy of the supraspinatus muscle on the magnetic resonance image was related to the size of the tear. In the thirteen shoulders in which the supraspinatus muscle was not atrophied or was mildly atrophied, the size of the tear averaged 4.6 ± 3.4 square centimeters; the average age of the patients was 5 1 ± 13 years. In the seventeen shoulders in which the supraspinatus muscle was moderately or severely atrophied, the average size of the tear of the rotator cuff was 19.3 ± 8.4 square centimeters; the average age of the patients was 65 ± 10 years. In none of the three shoulders in which the tear was acute was the supraspinatus muscle atrophied, but the average size of those three tears was 10 ± 3 square centimeters; the average age Of these patients was 32 ± 1 1 years. In contrast, none of the thirty-one rotator cuffs that did not have a complete tear in patients who had had symptoms of impingement for more than one year were associated with atrophy of the supraspinatus muscle; the average age of these patients was 42 ± 12 years. On an image made with a long repetition time and echo time (2500 and seventy milliseconds) of another patient s shoulder, a tear in the infraspinatus tendon (black arrows) is seen. THE JOURNAL OF BONE AND JOINT SURGERY

8 V... MAGNETIC RESONANCE IMAGING OF THE SHOULDER 23 FIG. 7 Axial image made at the level of the coracoid process (repetition time, 800 milliseconds; echo time, twenty milliseconds), showing a wedgeshaped defect on the posterolateral aspect of the humeral head, indicative of a Hill-Sachs defect (arrow). Impingement Syndrome and Intact Tendons Eighteen of the thirty-one rotator cuffs that did not have a complete tear were inspected on both surfaces during arthroscopy (Table III). In addition, nine were inspected during open acromioplasty and nine, during arthroscopic acromioplasty. An arthroscopic finding of degeneration or a partial tear of the cuff, rather than inflammation of the cuff, could be correlated with the findings on the magnetic resonance images and evaluated statistically. Eleven of these eighteen shoulders were found to have degeneration or a partial tear at the time of arthroscopy, and the average score on the magnetic resonance images was 3.5 ± 0.8 points; the average age of the patients was 43 ± 10 years. For the remaining seven shoulders, for which the diagnosis was tendinitis, the average score on the magnetic resonance images was 2. 1 ± 1.3 points; the average age of the patients was 40 ± 8 years. The remaining thirteen of the thirty-one shoulders were treated with open acromioplasty, and the average score on the magnetic resonance images was 2.6 ± 1.8 points; the average age of the patients was 41 ± 13 years. There were four false-positive diagnoses. In three shoulders, an incorrect diagnosis of a small, complete tear of the rotator cuff was made. The scores on the magnetic resonance images of these shoulders were 4, 5, and 6 points, and the images were interpreted as showing the tears to have an average size of 2.0 ± 1.1 square centimeters. Only one of these three shoulders had arthroscopic inspection of the undersurface of the cuff, which revealed evidence of a partial tear. Retrospective review showed that a coronal oblique image had not been made for the shoulder for which the score was 4 points, but the interpretation remained Unchanged. Coronal oblique images had been made for the other two shoulders. For one, retrospective review showed FIG. 8 FIG. 9 Fig. 8: Mid-plane axial image (repetition time, 800 milliseconds; echo time, twenty milliseconds) demonstrating a normal labrum and capsule, as seen by the normal signal void of the anterior (white arrow) and posterior aspect (white arrowhead) of the labrum. The anterior aspect of the labrum is more triangular and the posterior aspect is rounded. A signal of intermediate intensity at the base of the anterior and posterior aspects of the labrum was thought to represent articular cartilage (small black arrows). The anterior part of the capsule (open arrows) inserts close to the labrum and is seen to be separate from the subscapularis tendon (large black arrows), which is more anterior. Fig. 9: Axial image (repetition time, 2500 milliseconds; echo time, seventy milliseconds) made at the level of the mid-part of the glenoid fossa, demonstrating an anterior labral tear. There is high signal intensity, consistent with fluid, in the substance of the anterior part of the labrum and extending to the surface (black arrow). There is a small Hill-Sachs defect (open arrow). VOL. 73-A, NO. I, JANUARY 1991

9 24 J. P. IANNOTTI ET AL. TABLE II EVALUATION OF COMPLETE TEARS OF THE ROTATOR Cure: COMPARIsoN OF MAGNETIC RESONANCE IMAGING AND OPERATIVE DIAGNOSIS Magnetic Resonance-Im aging Diagnosis Magnetic Degeneration Resonance- Complete or Partial Operative No. Imaging Tear of the Tear of the Diagnosis (N = 88) ScoreB AgeB Rotator Cuff Rotator Cuff Tendinitis Normal (Points) (Yrs.) Completetearof ± ± the rotator cuff Impingement ± ± (without complete (False pos.) tear of the rotator cuff) Labraltear 9 1.1±0.9 26± (no dislocation) Normal ± ± (False pos.) B Mean and standard deviation. 13 an intact tendon with tendinitis (score, 3 points), and for the other, the interpretation remained unchanged (score, 6 points). The fourth false-positive image had been interpreted as showing degeneration or a partial tear of the cuff. At open and arthroscopic evaluation, however, only hyperemia on the undersurface of the tendon and marked thickening of the subacromial bursae were seen; the operative diagnosis was tendinitis. Three magnetic-resonance images were false negative. For one shoulder, an incorrect diagnosis of tendinitis had been made on the basis of the images, even though moderate degeneration and fibrillation of the undersurface of the supraspinatus tendon were seen with the arthroscope. In the other two shoulders, the clinical symptoms and operative findings were of tendinitis of the rotator cuff secondary to impingement, but the magnetic resonance images were normal (score, 0 points). Retrospective review did not change the original interpretation. In summary, with regard to the thirty-one shoulders in which the tendons were intact, the magnetic resonance images were false positive for four, with three of the four readings being unchanged by retrospective evaluation, and the images were false negative for three, with two of the three readings being unchanged by retrospective evaluation (Table III). Of the shoulders that were inspected arthroscopically, for nine in which the rotator cuff was degenerated FIG. 10 FIG. II Fig. 10: Axial gradient-echo image (repetition time, 600 milliseconds; echo time, fifteen milliseconds; flip angle, 70 degrees) demonstrating detachment of the labrum (black arrow) and the capsule (white arrow) from the glenoid. Fig. 11: Axial image (repetition time, 2500 milliseconds; echo time, eighty milliseconds) demonstrating a Type-Ill capsule. A very medial capsular insertion (white arrow) is seen in a patient who had recurrent anterior dislocations. The anterior aspect of the labrum is rounded and blunted at this level, but it was seen to be torn on images of sections made proximal to this level. ThE JOURNAL OF BONE AND JOINT SURGERY

10 MAGNETIC RESONANCE IMAGING OF THE SHOULDER E C) 20 U) SURGICAL SIZE cm2 FIG. 12 Correlation of the size of a complete tear of the rotator cuff as seen on magnetic resonance imaging compared with that seen at operation. or partially torn the images were true positive, and for five in which the cuff was inflamed and the bursae were thickened (tendinitis) the images were true positive. Of the thirteen shoulders that were not examined arthroscopically, on the basis of the magnetic resonance images four were diagnosed as having degeneration or a partial tear of the cuff and six, as having tendinitis. Of the fifteen asymptomatic subjects, in thirteen the magnetic resonance images were completely normal (true negative) and in two, the magnetic resonance images suggested the presence of mild tendinitis (score, 1 point) and were considered false positive. Sensitivity, Specificity, and Predictive Value The use of magnetic resonance images to differentiate between the several pathological conditions affecting the rotator cuff was studied (Table IV). The value of the images in the differentiation between a complete tear and an intact tendon was calculated in eighty-eight shoulders (Tables II and III). In the diagnosis of a complete tear of the rotator cuff, the sensitivity was 100 per cent and the specificity was 95 per cent. The predictive value of a positive study was 92 per cent and the predictive value of a negative study was 100 per cent. The ability of magnetic resonance images to differentiate between degeneration or a partial tear of the cuff and tendinitis was evaluated in the eighteen shoulders in which the tendons were intact and in which the cuff was evaluated arthroscopically and in the six shoulders in which tendinitis was seen on magnetic resonance imaging and a labral tear was seen at operation. The sensitivity was 82 per cent and the specificity was 85 per cent. The predictive value of a positive study was 82 per cent and that of a negative study was 85 per cent. The ability of magnetic resonance imaging to differentiate between the thirty-one shoulders that had clinical symptoms of tendinitis secondary to impingement and the shoulders of the fifteen asymptomatic subjects was evaluated. The sensitivity of magnetic resonance imaging was 93 per cent and the specificity was 87 per cent. The predictive value of a positive test was 93 per cent and that of a negative test was 87 per cent. Associated Degenerative Changes of the Acromion and Acromioclavicular Joints Thirty shoulders that had a complete chronic tear of the rotator cuff had spurring of the acromion or acromioclavicular joint; the average age of these patients was 60 ± 1 1 years. Three shoulders that had an acute tear of the rotator cuff had no evidence of spurring at the time of operation or on the images. For sixteen of the seventeen shoulders in which the tendons were intact but the rotator cuff was degenerated or partially torn, spurring of the acromion or the acromioclavicular joint was noted on magnetic resonance studies. In eight of the fourteen shoulders for which the diagnosis was tendinitis, spurring of the acromion or the acromioclavicular joint was seen on magnetic resonance images. None of the shoulders that had a labral tear or a subluxation, and none of the shoulders of the normal VOL. 73-A, NO. I, JANUARY 1991

11 26 i.. IANNOTTI ET AL. TABLE III EVALUATION OF THE INTACT ROTATOR-Cure TENDONS: COMPARISON OF MAGNETIC RESONANCE IMAGING AND OPERATIVE DIAGNOSIS Magnetic Resonance-Imaging Diagnosis Magnetic Degeneration Resonance- Complete or Partial Operative Imaging Tear of the Tear of the Diagnosis No. ScoreB AgeB Rotator Cuff Rotator Cuff Tendinitis Normal (Points) (Yrs.) Impingement ± ± Degeneration ± ± or partial (False pos.) (False neg.) tear of the rotator cuff Tendinitis ± ± (False pos.) (False neg.) Openacro ±1.8 41± mioplastyt (False pos.) (False neg.) Labral tear ± ± (no dislocation) Normal ± ± (False pos.) B Mean and standard deviation. t Shoulders that were not evaluated arthroscopically. subjects, had spurring. The average age of the patients who frayed glenoid labrum without a tear (Type 2) had been had spurring was 43 ± 9 years and the average age of those made. who did not was 34 ± 1 1 years. The remaining four shoulders had multidirectional instability. The studies showed the labrum to be frayed and Labral Anatomy blunt but intact (Type 2) in one and normal in another; both At operation, three operative diagnostic categories interpretations of the magnetic resonance-imaging studies were considered: a torn glenoid labrum, a frayed and blunted were found to be accurate at operation. For a third shoulder, labrum without a tear, and a normal glenoid labrum (Table internal degeneration was diagnosed on the basis of the V). Of the eighteen dislocated shoulders, all fourteen that imaging studies, but the labrum was seen to be normal at had recurrent unidirectional instability were found to have operation. This was considered a true-negative result, bean anterior tear of the glenoid labrum at operation. For cause it is not possible to distinguish a normal labrum from thirteen of these shoulders, the correct diagnosis had been one in which there is internal degeneration by gross inmade preoperatively on the basis of the imaging studies. spection during an operation. In the fourth shoulder, the For the fourteenth shoulder, a false-negative diagnosis of a labrum was normal, although a frayed and blunt but intact TABLE IV SENSITIVITY, SPECIFICITY, AND PREDICTIVE VALUE: COMPARISON OF MAGNETIC RESONANCE IMAGING AND OPERATIVE DIAGNOSIS Predict. Value Predict. Value Differential Diagnosis Sensitivity Specificity for Pos. Test for Neg. Test (Per cent) (Per cent) (Per cent) (Per cent) Complete tear of the rotator cuff or an intact tendonb (n = 88) Degeneration or partial tear of the rotator cuff or tendinitist (n 24) Normal or impingement syndrome (intact tendon)t (n = 46) Labral tear or frayed or blunted labrum or normalt (n = 39) B See Table II. t See Table III. See Table V. THE JOURNAL OF BONE AND JOINT SURGERY

12 MAGNETIC RESONANCE IMAGING OF THE SHOULDER 27 TABLE V EVALUATION OF THE ANATOMY OF THE GLENOID CAPSULE AND LABRUM: COMPARISON OF MAGNETIC RESONANCE IMAGING AND OPERATIVE DIAGNOSIS Magnetic Resonanc c-imaging Diagnosis Operative Torn Frayed or Blunted Internal Degeneration Diagnosis No. (Type 3 or 4) (Type 2) (Type 1) Normal Torn ant. disloc., 1 ant. sublux., 3 labral tears 1 ant. disloc., I labral tear (both false neg.) Frayed or multidirect. 0 0 blunted instabil., 2 labral tears, 3 impinge. syndromes Normal multidirect. instabil. (false pos.) I labral (false 1 multidirect. instabil. tear neg.) I 0 multidirect. instabil., I 1 impinge. syndromes labrum had been diagnosed on the basis of the imaging studies (a Type-2 false-positive result). For three of the seven shoulders that had an anterosuperior tear of the glenoid labrum without instability, the image was true positive for a tear. For two of the seven shoulders, the image was true positive for a frayed and blunted labrum without a tear. For the remaining two shoulders that had a complete labral tear, the image was considered false negative: one had been thought to have a frayed and blunt but intact labrum (Type 2) and the other, internal degeneration (Type 1). The capsule and labrum were evaluated arthroscopically in fourteen shoulders that had symptoms of impingement syndrome as well as an intact rotator cuff. For three shoulders, the image was true positive, in that it showed the anterior part of the glenoid labrum to be frayed or blunted but intact, and for eleven it was true negative, in that it showed a normal labrum. Considering all three operative categories of anterior labral anatomy, the sensitivity of magnetic resonance imaging was 88 per cent and the specificity was 93 per cent. The predictive value of a positive test was 97 per cent and that of a negative test was 81 per cent (Table IV). Hill-Sachs lesion: A wedge-like defect on the posterolateral aspect of the humeral head proximal to the coracoid process was identified as a Hill-Sachs lesion in thirteen of the thirty-nine shoulders in which the labrum and capsule were inspected. These lesions were found only in patients who had a definite history of recurrent anterior dislocation. They were not found in association with recurrent anterior subluxation without dislocation, multidirectional instability, or an isolated labral tear. The findings on the images were confirmed by arthroscopy in twenty-nine shoulders. Glenoidfracture: There were four fractures of the glenoid rim, all of which were associated with a history of recurrent anterior dislocation of the shoulder. Prospectively, two fractures were diagnosed correctly with magnetic resonance imaging. For the other two fractures, the images were considered to be false negative, as the fractures were clearly noted on them retrospectively. Type ofcapsule: It was possible to visualize the capsule and the glenohumeral ligaments with magnetic resonance imaging. Thinning and redundancy of the capsule and the area and type of the insertion of the capsule into the glenoid margin (Type 1, 2, or 3) could be assessed well. In this study, a Type-2 or Type-3 capsule was found in eleven of the thirteen shoulders that had recurrent anterior dislocation. In contrast, only two of the remaining twenty-six shoulders in which the capsule and the glenohumeral ligaments were visualized had this configuration. Discussion The greatest clinical value of magnetic resonance imaging of the shoulder is its ability to define complete tears of the rotator cuff, demonstrate the size of the tears, and reveal associated atrophy of the supraspinatus muscle. Magnetic resonance imaging is the first non-invasive technique with the ability to reliably define pathological changes that are associated with chronic impingement, such as tendinitis or degeneration of the tendon. Our data demonstrate the value of magnetic resonance imaging in the definition of the spectrum of lesions of the rotator cuff and abnormalities of the capsule and labrum that are associated with a painful shoulder. Neither ultrasonography nor arthrography defines these clinically important disease states The greatest value of ultrasonography is that it is a low-cost non-invasive study with which a complete tear of the rotator cuff can be defined accuratelyh2i. Its limitations are its inability to define the size of a tear of the cuff and to visualize partial tears, degeneration of the cuff, or labral abnormalities; additionally, the accuracy of the study depends substantially on the experience of the examiner. Arthrography is an invasive study that has been reported to be very accurate for the definition of a complete tear of the rotator cuff 2 9 #{176}23. However, in a previous report, magnetic resonance imaging was found to have greater sensitivity and specificity than arthrography in the same population of operatively treated VOL. 73-A, NO. I, JANUARY 1991

13 28 J. P. IANNOTTI ET AL. patients, some of whom had a small complete tear (one to two centimeters) or a partial-thickness tear of the rotator cuff. Arthrography was shown to be least accurate for these small complete and partial tears37. Computed arthrotomography is an accurate method with which to evaluate the glenoid rim, the glenoid labrum, the glenohumeral capsule, and the humeral head for Hill- Sach lesions Our study and others showed magnetic resonance imaging to be as accurate as computed arthrotomography for the evaluation of these structures. Unlike computed arthrotomography, magnetic resonance imaging is non-invasive, and it also allows evaluation of the rotator cuff for tendinitis, degeneration, or complete tears. Although magnetic resonance imaging was accurate in the evaluation of the rotator cuff and the capsular mechanism of the shoulder in our study, the accuracy may depend on a number of technical factors, including the use of a highfield-strength magnet and properly designed surface coils, the ability to obtain oblique sections, and good homogeneity of the magnetic field away from the center of the bore. Furthermore, accurate interpretation of these images depends on an experienced reader, and attention must be paid to the outlined magnetic-resonance criteria (the grades and types defined earlier, as well as the scoring system presented in Table I). Magnetic resonance imaging is costly, but although the information that can be obtained from a complete high-resolution magnetic-resonance study could be obtained from multiple other tests, the cost of those tests would be inordinately high. Thus, the cost of magnetic resonance imaging can be justified. To date, the main purpose of preoperative evaluation of the rotator cuff has been to exclude the possibility of a complete tear. In this study, magnetic resonance imaging enabled us to differentiate between a complete tear of the rotator cuff, degeneration or a partial-thickness tear, chronic tendinitis, and normal tendons. The ability of magnetic resonance imaging to define the spectrum of lesions of the rotator cuff, as well as the associated findings of muscle atrophy and degenerative changes of the acromion and the acromioclavicular joint, may prove useful in the non-operative management of these patients and in the process of operative decision-making. At this time, the clinical data are insufficient for a complete understanding or full use of all of the information that can be obtained from magnetic resonance images. Additional study is needed. This study demonstrated a direct correlation between the extent of degenerative changes of the acromion and the acromioclavicular joint and the severity of the lesion of the rotator cuff. The osseous changes and the severity of a chronic lesion of the rotator cuff were found to worsen with increasing age The factors of age and the severity of the lesion of the rotator cuff could not be separated except in the eighteen shoulders in which the tendons were intact and the rotator cuff had been evaluated arthroscopically. In this group, the degenerative changes of the acromioclavicular joint and the acromion were the most frequent (94 per cent) in the shoulders in which the cuff was degenerated or partially torn and the least common (57 per cent) in those that were affected by tendinitis. The average age of the patients was not statistically different between these two groups, which suggests that osseous changes of the acromioclavicular joint and acromion are related to the progression of chronic lesions of the rotator cuff. The magnetic resonance images verified that, as was suspected clinically3 12, there is a relationship between tendinitis of the rotator cuff and glenohumeral instability. It is our clinical impression that symptoms of tendinitis of the rotator cuff are sometimes associated with more subtle forms of glenohumeral instability. In some patients, the initial symptoms are related to tendinitis of the rotator cuff. In these patients, the tendinitis often resolves with appropriate management of the instability. Magnetic resonance imaging of both the rotator cuff and the capsular mechanism may be useful in the evaluation of these often difficult cases. References 1. BELTRAN, JAVIER; GRAY, L. A. ; BOOLS, J. C. ; ZUELZER, WILHELM; WEIS, L. 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