Comparative evaluation of the lateral notch sign in patients with ACL lesion

Objectives: The lateral notch sign (LNS) is a pathologic depression of the lateral femoral condyle, which is visible on a standard lateral view radiograph. It is caused by the impact of the condyle with the postero-superior aspect of the lateral tibial plateau following an ACL rupture-causing knee sprain. Few studies have assessed the LNS and no study has yet evaluated the interobserver detection of the sign. Aim of this study is to qualitatively and quantitatively assess the LNS in patients with a lesion of the ACL. The hypotheses are: the LNS is an indirect sign of ACL lesion; the is no interoberver and no intra-observer variability of detection of the LNS; the LNS is mostly associated to a valgus/external rotation trauma; there is a correlation between the LNS and meniscal lesion.