Prevalence and MRI Detection of Ramp Lesions in ACL-Deficient Knees: A Prospective Study

Background: Meniscal ramp lesions are mostly missed lesions and are commonly associated with anterior cruciate ligament (ACL) injuries. This is characterized by peripheral tears at the meniscocapsular junction of the posterior horn of the medial meniscus. These injuries are often underdiagnosed due to limitations in standard imaging protocol and arthroscopic techniques. Objectives: This study aimed to determine the prevalence of meniscal ramp lesions among the patients undergoing primary ACL reconstruction at a tertiary level military hospital. In addition to it, it also aims to evaluate the diagnostic sensitivity of magnetic resonance imaging (MRI). Methods: A prospective cross-sectional study was conducted from October 2021 to January 2023. Institutional review board (IRC) approval was obtained. Total 163 patients that underwent primary ACL reconstruction were included meeting inclusion criteria. Ramp lesion was identified via arthroscopic evaluation of the posteromedial compartment through a transnotch view and a posteromedial portal. This finding was compared to the preoperative MRI findings to assess diagnostic accuracy of MRI. Results: Arthroscopic evaluation identified ramp lesions in 8 out of 163 patients (4.9%). In comparison to preoperative MRI, which detected only 2 cases, yielding a sensitivity of 25%. Ramp lesions were significantly associated with high-grade pivot shift and delayed the surgery beyond six months after injury (p < 0.05). Conclusion: Our study found, MRI has low sensitivity in detecting meniscal ramp lesions. It is imperative to explore the posteromedial compartment in all index cases of ACL reconstruction to detect hidden ramp lesion. This would result in restoration of knee stability and preventing surgical failure. In addition to this, these findings bear particular importance for military personnel, which helps in restitution of knee stability, facilitate timely return to duty, and reduce the risk of long-term disability.