Arthroscopic posteromedial drive-through test in posterior cruciate ligament insufficiency: a new diagnostic test
The study investigated the prevalence of the posteromedial drive-through sign in patients undergoing knee arthroscopy and determined its relationship to posterior cruciate ligament (PCL) insufficiency. A retrospective review was performed on 1,015 patients undergoing knee arthroscopy from 2009 to 2012 at two institutions. During knee arthroscopy, the ability to pass the arthroscope easily between the medial femoral condyle and the PCL is considered a positive posteromedial drive-through sign. We calculated the accuracy, sensitivity, specificity, positive predictive value and negative predictive value of posteromedial drive-through sign for diagnosis of PCL ruptures. The posterior laxity measured by Telos stress radiograph was compared between the posteromedial drive-through sign (+) and (−) patients with PCL ruptures. Of the 1,015 patients, 73 (7 %) had a positive posteromedial drive-through sign. For the diagnosis of PCL rupture, a posteromedial drive-through sign had an overall accuracy of 97.6 %, sensitivity of 78.8 %, specificity of 99.3 %, positive predictive value of 91.7 % and negative predictive value of 98.1 %. For the ligament laxity examination using stress radiographs, the mean posterior tibia translation was 13.8 ± 2.2 mm, while the mean posterior translation was 10.6 ± 2.4 mm in those with a negative posteromedial drive-through sign (p < 0.05). There was no relationship between a positive posteromedial drive-through sign and age and combined injuries (n.s.). A positive posteromedial drive-through sign strongly indicates the presence of PCL injuries and this arthroscopic sign is highly associated with grade III posterior knee instability. III.