Clinical Assessment of the Dynamic Shear Test for SLAP Lesions

Abstract

Objectives:Making the diagnosis of superior labrum anterior posterior (SLAP) lesions with physical examination remains challenging. The dynamic shear test is a recently described physical examination test which has been shown in two previous studies to have a likelihood ratio of 31.6 and 1.1 for making the diagnosis of a SLAP tear. The goal of this study was to determine the clinical utility of the dynamic shear test for making the diagnosis of SLAP lesions.Methods:This is a consecutive case series of patients who were studied prospectively who had a diagnostic arthroscopy by the senior author between 2007 and 2013 (N=674). All had a thorough physical examination preoperatively which included a dynamic shear test. Only Type II through V SLAP lesions were considered positive for a SLAP tears. A type I tear was considered a degenerative lesion and included in the control group. For statistical analysis, the patients were divided into three groups: a control group (n = 528) consisting of patients with no SLAP lesion but with other pathologies, an Isolated SLAP lesion group (n = 7), and a Concomitant SLAP group (n=139) who had a SLAP tear and some other shoulder pathology such as a rotator cuff tear or instability of the shoulder. Statistical analysis included determining sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), likelihood ratio (LR), and diagnostic accuracy (DA) of the dynamic shear test with and without other tests for SLAP tears.Results:The dynamic shear test was positive for 242 (45.8%) control patients, 6 (85.7%) patients with isolated SLAP lesions, and 79 (56.8%) of the concomitant SLAP patients. For isolated SLAP tears the dynamic shear test had a sensitivity of 85.7, specificity of 51.9, PPV of 1.8, NPV of 99.7, LR of 6.4, and DA of 54.4. In comparison, the LR for the active compression test was 0.7 and for the relocation test was 1.5. For patients with combined SLAP lesions with other pathologies, the dynamic shear test had a sensitivity of 58.2, specificity of 54.2, PPV of 35.99, NPV of 82.4, LR of 1.5, and DA of 55.0. Combining all three tests did not improve the LR for either isolated SLAP lesions or lesions with concomitant pathology.Conclusion:This study demonstrates that the dynamic shear test is sensitive but not specific for isolated SLAP lesions. With a likelihood ratio of over 6, it is one of the better tests for diagnosing isolated SLAP tears. However, in patients who have concomitant pathologies it is not as useful for making the diagnosis of a SLAP lesion.