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

Purpose: During arthroscopy of the shoulder, the ability to pass the arthro scope easily between the humeral head and the glenoid at the level of the a nterior 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 wi th SLAP lesions. The goal of this study was to examine the prevalence of th e drive-through sign in patients undergoing shoulder arthroscopy and to det ermine its relationship to shoulder instability, shoulder laxity, and to SL AP lesions. Type of Study: Case series. Methods: We prospectively studied 3 39 patients undergoing arthroscopy of the shoulder for a variety of diagnos is from 1992 to 1998, The drive-through sign was performed with the patient s in a lateral decubitus position and under general anesthesia. The drive-t hrough sign was correlated with preoperative physical findings, intraoperat ive laxity testing, and with intra-articular pathology at the time of arthr oscopy. 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 pos itive 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-thro ugh sign and increasing shoulder laxity, but not with SLAP lesions. Conclus ions: This study shows that a positive drive-through sign is not specific f or shoulder instability but is associated with shoulder laxity. This arthro scopic sign should be incorporated with other factors when considering the diagnosis of instability.