Superior labrum anterior to posterior (SLAP) lesions have been recognized as a cause of shoulder pain since the mid 1980s. Controversy regarding what was a normal variant and what was an abnormality that could be consistently associated with a patient’s symptoms surfaced almost immediately thereafter. Snyder and colleagues established the current understanding of the pathologic anatomy of SLAP lesions by recognizing the different types (I through IV) and the implications of their treatment ( Figs. 49-1 and 49-2 ). Although the true incidence of SLAP lesions is unknown, in the initial study by Snyder and colleagues, the percentage of SLAP repairs as a function of their overall surgical cases was quite low (3.3%). This percentage increased slightly to 4.7% in a follow-up study in 1995. Percentage rates have varied slightly from these low numbers in other series, but the published literature consistently suggests that SLAP lesions are uncommon injuries.
Nonetheless, disproportionate enthusiasm for this diagnosis has been expressed, causing some authors to call SLAP lesions the “plica of the shoulder.” SLAP repairs continue to be performed in the United States at a rate far in excess of that performed in Europe, perhaps in part because of the high incidence of false-positive radiologic interpretation of magnetic resonance imaging (MRI) scans. An investigation performed by Weber and Kauffman showed that up to 35% of community-read MRI scans were interpreted as either a labral tear or a “possible labral tear.”
Significant clinical findings upon examining the shoulder of patients with SLAP lesions are also inconsistent. Although a number of tests and clinical examination maneuvers have been suggested, all have proved to be difficult to validate ( Table 49-1 ). These issues create problems for the surgeon in the diagnosis of SLAP lesions preoperatively. The interpretation of intraoperative findings is also difficult; even experienced surgeons disagree regarding which findings represent a normal variant, such as a sublabral recess ( Fig. 49-3 ) that requires no treatment, and which findings benefit from repair.
| Clinical Test | Works Inconsistently | Failure to Validate |
|---|---|---|
| Snyder biceps compression test | Weber and Higgins ; Kim and McFarland | |
| Jobe relocation test | Weber and Higgins, 70% sensitivity Guanche and Jones, 73% sensitivity | Mileski and Snyder |
| Kibler anterior slide test | Kim et al. | |
| Liu crank test | Guanche and Jones Stetson | |
| O’Brien active compression test | Guanche and Jones Morgan and Burkhart | Ottl et al Kim and McFarland |
| Speed test | Holtby and Razmjou |
In more recent studies that have focused on complications, it has been found that patients often have residual symptoms after SLAP repair. Persistent discomfort with loose hardware, persistent rotator cuff defects, articular cartilage injuries, persistent synovitis, and low rates of return to sports have been reported after the procedure. Because arthroscopic SLAP repair is a technically demanding arthroscopic procedure that may be associated with significant complications, it is important to undertake the procedure only in the cases in which the potential reward from the procedure outweighs the risk. Making this determination involves carefully assessing the history, physical examination findings, and imaging findings and then critically condensing the results into a treatment plan that will vary for each patient.
History
Typically, a SLAP lesion is related to an overhead injury. Throwing injuries remain the largest subset of these events. Maffett et al. suggested that traction on the overhead or abducted arm is another common mechanism. Snyder et al. described the injury as being due to compression from a fall on the outstretched arm. Burkhart and Morgan described the “peel-back” mechanism by which anterior shoulder contracture causes structural changes leading to SLAP pathology. Overuse symptoms created by activities performed below the shoulder generally do not cause labral pathology, and positive MRI scans obtained in this subset of patients should be viewed with suspicion. Because natural degeneration of the labrum occurs with age, SLAP lesions are less common after age 40 years, with other shoulder pathology becoming more relevant and the SLAP lesion often being incidental to the true cause of the pain. Most persons with symptomatic SLAP lesions present with pain with overhead activities and mechanical popping, catching, or grinding. Isolated SLAP lesions are uncommon, and thus many of the symptoms may be masked by other diagnoses such as impingement, bicipital tendonitis, and acromioclavicular pain. Patients presenting with shoulder instability often have extension of the labral damage into the superior labrum, and a high index of suspicion is necessary in this subset of patients. For the most part, however, the history will be nonspecific, and recognizing the appropriate demographic in which SLAP lesions occur remains the most important part of the history.
Physical Examination
Identifying symptomatic SLAP lesions on physical examination remains challenging because significant clinical findings upon examination of the shoulders of patients with SLAP lesions are inconsistent. Although a number of tests and clinical examination maneuvers have been suggested, they have all proved to be difficult to validate. The only test that my colleague Kauffman and I identified as having reasonable sensitivity was the apprehension test, and even this test had poor sensitivity. The inability of other surgeons to reproduce the sensitivities and specificities described by the physician who originally performed the test led Kim and McFarland to state, “… our findings question the diagnostic value of the clinical assessment of SLAP lesions.” Snyder and colleagues continue to make the argument that “there is no physical finding specific for SLAP lesion of the shoulder.” Walsworth et al. noted that even combining tests did not improve the results of physical examination testing. Consistent with the history, the presence of other pathology can render the identification of SLAP pathology difficult. In my experience, SLAP lesions are difficult to diagnose clinically, and tests must be performed in the context of the clinical history and the appropriate patient demographic.
Imaging
Although arthrography and CT arthrography may have a limited role in the diagnosis of SLAP lesions, MRI remains the mainstay of preoperative imaging. Noncontrast MRI remains the most common tool used to diagnose labral pathology. Radiologic review of these studies remains highly variable, however. Prior work performed by my colleague Kauffman and I showed that up to 35% of community-read MRI scans were interpreted as either a labral tear or a “possible labral tear,” which is a worrisome statistic when the true incidence is probably between 3% and 5%. Clearly the orthopaedist will need to become confident in interpreting MRI images of the labrum if the study is to be useful. My colleague Higgins and I found that only 5 of 64 patients with surgically confirmed SLAP lesions were correctly diagnosed by the preoperative radiologist reading ; however, use of contrast material may improve these results ( Fig. 49-4 ). Overall, Belanger and Green noted that “preoperative … MRI was non-specific in identifying SLAP lesions,” and Mileski and Snyder stated that “diagnostic arthroscopy remains the only definitive way to diagnose SLAP lesions of the shoulder.” Clearly, orthopaedists who treat the shoulder will need to become facile in interpreting MRI scans of the shoulder, especially because numerous normal variants such as sublabral recesses can confound the interpretation of the scan. Despite advances in the performance and interpretation of MRI of the shoulder, surgeons need to be prepared to diagnose and treat SLAP lesions as they present at surgery. Arthroscopy is still the gold standard in the diagnosis of labral tears, and the surgeon who undertakes shoulder arthroscopy, especially for patients who fit the demographic of SLAP lesions, should have the necessary equipment and technical skills to perform SLAP repairs when these lesions become evident at surgery, despite MRI findings.
Decision-Making Principals
Decision making with regard to the treatment of patients who may have SLAP pathology remains difficult. As previously indicated, the diagnosis will rarely be made by a clear-cut history, physical examination, or imaging study. The clinical information that is available with regard to this complicated problem is straightforward on one subject: SLAP lesions are relatively rare. True incidence rates are not available, but a number of studies have suggested that the percentage of SLAP lesions as a function of the total number of cases remains fairly low. Snyder et al. had a percentage rate of 3% of their total shoulder cases, which increased to 5.9% in a subsequent follow-up study. My own study with Higgins had a 10-year percentage rate of 1.9%. Kim et al. had a rate of 6.6%, and Maffett et al. had the highest rate of 11.7%, in a series with a disproportionate number of anterior instability cases. It should be noted that all these series were performed in tertiary shoulder practices, where the rate might be expected to be higher than in the practice of a general orthopaedist. Review of American Board of Orthopaedic Surgery (ABOS) II data has shown a significant increase in the actual number and percentage of SLAP repairs among candidates, at more than 11%, suggesting that many of these repairs may fall outside accepted guidelines. Candid assessment of the percentage of SLAP lesions performed by each surgeon may allow one to assess the indications selected for repair.
Another important factor is age. Numerous authors have suggested that patients older than 40 years may be better served by arthroscopic biceps tenodesis than SLAP repair. The reasons are probably multifactorial, but again, labral degeneration is more common with age, and age-related biceps changes may make SLAP repair impractical. Older patients often have substantial additional pathology, the correction of which may further increase the morbidity of the procedure.
Initial nonoperative treatment of a suspected SLAP lesion remains the primary choice for virtually all patients. Blaine et al. showed a high rate of success with this approach. Whether the MRI diagnosis was false positive or the SLAP lesions healed is difficult to determine, but nonetheless the success rate was high. Careful observation and differential injection can further define additional treatment that may be needed, given that SLAP lesions rarely occur in isolation. Clearly a radiologic report of a “possible SLAP lesion” is not in itself an indication for surgery. Assuming that the history, physical examination findings, imaging study findings, and demographic category of the patient fit the diagnosis of a SLAP lesion and nonoperative treatment fails, then diagnostic arthroscopy can be undertaken to identify if in fact a symptomatic SLAP lesion is the cause of the symptoms. Even when diagnostic arthroscopy is performed, the decision making can be difficult. Numerous studies have shown that even experienced surgeons vary widely in their determination of which lesions are pathologic. Whereas special assessments such as the sulcus score of Mihata et al. may prove useful, even visual diagnosis of SLAP lesions at surgery remains controversial. Although diagnosis of type III and IV lesions is relatively straightforward, diagnosis of type I and II SLAP lesions remains elusive. Data from both Snyder et al. and my own study with Higgins suggest that the presence of granulation tissue at the base of the labral attachment indicates a high specificity for a SLAP lesion ( Fig. 49-5 ). Given the high complication rates reported recently with SLAP repair, the decision to perform such a repair should not be made lightly, and the preponderance of evidence should be upon indications for repair. As previously suggested, patients older than 40 years may be better served by a biceps tenodesis procedure.
