Clinical significance of the arthroscopic drive-through sign in shoulder surgery

Purpose: During arthroscopy of the shoulder, the ability to pass the arthroscope easily between the humeral head and the glenoid at the level of the anterior band of the inferior glenohumeral ligament is considered a positive drive-through sign. The drive-through sign has been considered diagnostic of shoulder instability and has been associated with shoulder laxity and with SLAP lesions. The goal of this study was to examine the prevalence of the drive-through sign in patients undergoing shoulder arthroscopy and to determine its relationship to shoulder instability, shoulder laxity, and to SLAP lesions. Type of Study: Case series. Methods: We prospectively studied 339 patients undergoing arthroscopy of the shoulder for a variety of diagnosis from 1992 to 1998, The drive-through sign was performed with the patients in a lateral decubitus position and under general anesthesia. The drive-through sign was correlated with preoperative physical findings, intraoperative laxity testing, and with intra-articular pathology at the time of arthroscopy. Results: The arthroscopic evaluation showed that drive-through sign was positive in 234 (69%) shoulders. For the diagnosis of instability, the drive-through sign had a sensitivity of 92%, a specificity of 37.6%, a positive predictive value of 29.9%, a negative predictive value of 94.2%, and an overall accuracy of 49%. There was an association between the drive-through sign and increasing shoulder laxity, but not with SLAP lesions. Conclusions: This study shows that a positive drive-through sign is not specific for shoulder instability but is associated with shoulder laxity. This arthroscopic sign should be incorporated with other factors when considering the diagnosis of instability.