Arthroscopy : The Journal of Arthroscopic and Related Surgery 4(1):21-24 Published by Raven Press, Ltd. © 1988 Arthroscopy Association of North America

Correlation of Pathology Arthrotomography and

Observed in Double Contrast Arthroscopy of the Shoulder

Jeffrey S. Kneisl, M.D., Howard J. Sweeney, M.D., and Milton L. Paige, M.D.

Summary: Correlation of double contrast arthrotomography (DCAT) of the shoulder and arthroscopic surgery diagnostic results have been undertaken in 55 patients with persistent shoulder pain or involuntary shoulder instability. During the period March 1984 to December 1986, 55 patients underwent DCAT followed by videotaped diagnostic shoulder arthroscopy. The primary indica- tion for DCAT was persistent pain in 36 patients and instability in 17 patients. DCAT was performed according to the method of E1-Khoury and Albright, and all arthroscopies were performed in a similar fashion by the senior author (HJS). Both tests were reviewed separately, retrospectively, and their results were correlated. For combined (anterior and posterior) labral pathology, the sensitivity/specificity for the instability group was 0.91/0.91, respectively; sen- sitivity/specificity for the pain group was 0.63/0.94. DCAT accurately depicted the status of 76% of anterior labrums and 96% of posterior labrums. For com- plete rotator cuff tears, sensitivity/specificity was 1.0/0.94. The status of a complete rotator cuff tear was accurately depicted in 91% of patients. Partial rotator cuff tears were missed in 83% of patients by DCAT. The presence or absence of loose bodies was accurately represented by 96% of DCAT. Arthros- copy showed that 71% of the instability patients had a labral tear, compared with 44% of the pain patients. Rotator cuff pathology was present in 12% of instability patlents and 42% of pain patients. These findings indicate that DCAT may be a conditionally reliable test in the diagnosis of shoulder insta- bility. DCAT must be considered inconclusive, however, in the painful shoulder without instability. Its usefulness as a preoperative screening test is discussed, and a diagnostic algorithm is presented. DCAT does not equal the diagnostic accuracy of shoulder arthroscopy. Key Words: Double-contrast arthrotomography--Shoulder instability--Rotator cuff tear.

The advent of shoulder ar throscopy has placed another powerful tool in the hands of the ortho- paedic surgeon. Despite continued reports of the usefulness of diagnostic and therapeutic shoulder ar throscopy (1-5), the procedure is still questioned by some authorities. The common goals of shoulder surgeons are to (a) identify and treat shoulder pa- thology, (b) determine whether therapeutic opera- tive intervention is indicated, and (c) if so, deter- mine whether Conventional shoulder ar throtomy or

From Evanston Hospital, Evanston, Illinois. Address correspondence and reprint requests to Dr. H. J.

Sweeney, Evanbrook Orthopaedic Associates, Ltd., 2500 Ridge Avenue, Evanston, IL 60201, U.S.A.

ar throscopic surgery would most benefi t the pa- tient.

The p r o p e r roles for d iagnost ic r a d i o c o n t r a s t evaluation versus diagnostic shoulder a r throscopy are not precisely known. The purpose of this study is to clarify the relative roles of double cont ras t ar throtomography (DCAT) and diagnostic shoulder a r th roscopy in separate groups of pat ients with painful or unstable shoulders. The objectives are to correlate findings of DCAT and diagnostic shoulder ar throscopy in these patients and to determine the sensitivity, specificity, and accuracy of DCAT re- garding the anter ior and pos ter ior labrum, loose bodies, and full and partial rotator cuff tears.

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22 J. S. KNEISL ET AL.

MATERIALS AND METHODS

During the period March 1984 through December 1986, 55 patients underwent DCAT followed by vid- eotaped diagnostic shoulder arthroscopy. Forty- two patients were male and 13 were female. Thirty- six patients had a primary complaint of shoulder pain unrespons ive to s tandard conserva t ive therapy, including rest from activities, nonsteroidal ant i - inf lammatory medica t ions , and physical therapy. Seventeen patients had a primary com- plaint of involuntary shoulder instability. Two pa- tients' primary complaints could not be individual- ized to either group. The age range in the pain group was 18-65 years (average 47). The age range in the instability group was 16-60 years (average 26).

Standard DCAT was performed in the manner of EI-Khoury et al. (6). Double contrast shoulder arthrotomograms were performed utilizing 4 cc of 60% Renografin and 10 cc of room air. The patients were then asked to exercise the involved shoulder and were positioned in the lateral decubitus posi- tion with the scapula perpendicular to the x-ray table. Scout arthrograms and pluridirectional to- mography at 2-ram intervals were performed; the average number of images obtained was 10. The arthrotomograms were reviewed retrospectively and blindly; abnormalities regarding anterior/poste- rior labral structure, loose bodies, and the rotator cuff were recorded.

Diagnostic shoulder arthroscopy was performed on each of those patients utilizing a standard tech- nique by the senior author (H.J.S.). All arthro- scopic procedures were videotaped and reviewed re t rospect ively and blindly. Abnormali t ies re- garding the anterior/posterior labral structures, loose bodies, and rotator cuff were recorded.

Data were compiled and tabulated, and are avail- able upon request. Statistical correlations were made utilizing the following definitions:

Sensitivity: True positives

True positives and false negatives

where a true positive is a diagnostic positive finding made on DCAT and confirmed at arthroscopy. Sen- sitivity decreases as the number of false negatives increases.

Specificity: True negatives

True negatives and false positives

where a true negative is the absence of a finding on

Arthroscopy, Vol. 4, No. 1, 1988

DCAT that is confirmed by arthroscopy. Specificity decreases as the number of false posi t ives in- creases.

True positives and true negatives Accuracy:

Total

This represents the percentage of accurately repre- sented arthroscopic diagnostic findings by DCAT for the structure under consideration.

For the purpose of this study, the diagnostic ac- curacy of shoulder arthroscopy was assumed to be 100%.

RESULTS

For labral pathology, the sensitivity/specificity for the instability group was 0.91/0.91, respectively; anterior labral accuracy was 82%, posterior labral accuracy was 94%. In the pain group, the sensi- tivity/specificity was 0.63/0.94. Anterior labral ac- curacy of 75% was less than posterior labral accu- racy of 97%.

For rotator cuff pathology, no full rotator cuff tears were diagnosed by either DCAT or shoulder arthroscopy in the instability group. Partial rotator cuff tears in this group were missed by DCAT in 100% (two tears in two patients). In the pain group, full rotator cuff tear sensitivity/specificity was 1.0/0.91, respectively, with a 93% accuracy for DCAT. Partial rotator cuff tears were missed in 83% (five tears in six patients).

For loose bodies, their presence or absence was accurately depicted by DCAT 100% in the insta- bility group and 94% in the pain group.

Twelve of 17 instability patients had a labral tear (71%). Only two of 17 instability patients had a ro- tator cuff tear, both partial (12%).

Sixteen of 36 in the pain group had a labral tear (44%). Forty-two percent had rotator cuff tears; six of 36 had partial and nine of 36 had full rotator cuff tears.

DISCUSSION

Previous investigators have reported documenta- tion of labral pathologic conditions with DCAT (6-14). The initial experience of E1-Khoury et al. with DCAT included only patients with shoulder in- stability (6). A subsequent report from the same in- stitution included seven patients without instability, all of whom were reported to show absence of la- bral pathology (11). No false negatives or false posi- tives were reported. Kleinman et al. reported a

DOUBLE CONTRAST ARTHROTOMOGRAPHY 23

series of 67 patients, 26 with positive DCAT for labral tears (9). Of positive DCAT, 58% had no clin- ical evidence of instability. Only one false positive was reported with an "est imated" sensitivity of 100% and specificity of 80%. They concluded that many patients without clinical instability have la- bral pathology. Most recently, EI-Khoury et al. re- ported a mixed pain instability series of 114 patients (15). Labral tears were revealed arthrotomographi- cally in 86% of instability patients and 40% of pain patients. Only 50% of patients had DCAT findings correlated at surgery; 80% of those patients under- going surgery had anatomic instability. No false positives and two false negatives were reported (Table 1).

In a review of the literature, one may be led to conclude the following: (a) DCAT consistently demonstrates a high percentage of labral pathology in instability patients, (b) DCAT demonstrates a much lower incidence of labral pathology in clini- cally stable shoulders, and (c) rare false positive and false negative reports are made, implying a sen- sitivity/specificity approaching 1.00.

E1-Khoury et al., Kleinman et al., and others make a strong argument for DCAT as a useful screening test in all anatomic or functionally un- stable shoulders and in patients with shoulder pain (9,15).

Our statistics demonstrate that DCAT must be evaluated more carefully. Our findings, in which the arthroscopic incidence of labral pathology in in- stability is 71%, compare favorably with those of others (64-88%). DCAT sensitivity/specificity was 0.91/0.91 for labral pathology in the instability group. Errors were false negative DCAT in three of four cases. In patients with clinical shoulder insta- bility, DCAT helps identify specific labral condi- tions that may be causing or contr ibut ing to shoulder instability and is reliable enough to assist in planning a lesion-specific operative procedure.

In the clinically stable yet persistently painful shoulder, we found the incidence of labral tear to be

TABLE 1. Double contrast arthrotomography confirmed at surgery (%)

Pain group Instability group

No. % No. %

1982 McGlynn et al. 1984 Kleinman et al. 1986 EI-Khoury et al. 1987 Present

7 0 1982 McGlynn et al. 28 68 40 38 1984 Kleinman et al. 27 41 45 27 1986 E1-Khoury et al. 69 64 36 100 1987 Present 17 100

44%. This compares favorably with 40% as re- ported by EI-Khoury et al. This implies that 60% of these patients' problems may not be directly re- lated to the glenoid labrum.

It is likely that the high incidence (42%) of partial and full thickness rotator cuff tears in the pain group reflects the underlying source of these pa- tients' problems. Unfortunately, DCAT accuracy in evaluation of the rotator cuff is low (13%) for par- tial rotator cuff tears. We have not found DCAT to be useful in the detection of partial thickness tears in the impingement syndrome (16,17).

Additionally, the labral sensitivity/specificity for DCAT in the pain group was 0.63/0.94, reflecting a significant false negative rate. Recall that Pappas and Boland (18) and later Ogilvie-Harris and Wiley (5) have reported successful treatment of functional instability of the shoulder with arthroscopic exci- sion of labral tears. They concluded that a torn la- brum without instability can be treated by resection of the torn portion, relieving symptoms and im- proving function.

It appears that DCAT is not indicated in the screening of the cl inically stable yet painful shoulder, owing to its low sensitivity for labral tears and partial rotator cuff tears. We advocate that those patients, should conservative measures fail, would benefit diagnostically and therapeutically by shoulder arthroscopy.

CONCLUSIONS

These findings indicate that DCAT can be a useful, reliable test in the diagnosis of shoulder in- stability in specific instances. Its primary indication is in the patient with a history and physical exami- nation consistent with clinical instability whose di- rection is unclear or undocumented. For this pa- tient, DCAT could help the physician plan a more lesion-specific procedure.

DCAT is less conclusive and less helpful in the management of the painful yet clinically stable shoulder. Many labral tears and most partial rotator cuff tears are missed by DCAT in this population. The majority of the lesions diagnosed at arthros- copy can be t reated arthroscopically, making DCAT superfluous for this patient population.

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