Ramp Lesions of the Medial Meniscus in Patients Undergoing Primary and Revision ACL Reconstruction: Prevalence and Risk Factors

BACKGROUND: Ramp lesions are peripheral tears of the posterior horn of the medial meniscus that involve the meniscocapsular attachments or red-red zone and typically occur in conjunction with anterior cruciate ligament (ACL) ruptures. PURPOSE: To identify the prevalence of, and risk factors for, ramp lesions in a large cohort of patients undergoing primary and revision ACL reconstruction. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: We queried our institutional registry of patients who underwent primary or revision surgical treatment for an ACL injury. Those who underwent preoperative magnetic resonance imaging (MRI) at our facility were included in the study. Clinical details were extracted and verified using electronic records. All preoperative MRI scans were reviewed by a musculoskeletal radiologist for the presence of a ramp lesion. Stable ramp lesions were defined as a peripheral posterior horn medial meniscal tear identified on MRI but either not identifiable with viewing and probing from the anterior portals or, if identified, not displaceable with anteriorly directed probing. Unstable ramp lesions were defined as peripheral posterior horn medial meniscal tears at the meniscocapsular junction that were identifiable at the time of surgery and displaced into the medial compartment with probing. The prevalence of stable and unstable ramp lesions was calculated. Demographic, injury, and imaging parameters were determined using univariate statistics. RESULTS: A total of 372 patients were included. The overall prevalence of ramp lesions was 42% (155/372). Unstable ramp lesions were present in 73 (20%) patients, and stable ramp lesions were present in 82 (22%) patients. The presence of any ramp lesion (stable or unstable) was associated with bone marrow edema of the posteromedial tibia on MRI (odds ratio [OR], 3.0; P < .0001), a contact injury mechanism (OR, 1.8; P = .02), and a concurrent lateral meniscal tear (OR, 1.7; P = .02). No demographic, injury, surgical, or radiological variable was associated with a stable versus unstable ramp lesion. CONCLUSION: The overall prevalence of a ramp lesion in patients treated for ACL ruptures at our institution was 42%. The presence of bone marrow edema of the posteromedial tibia, a contact injury mechanism, or a lateral meniscal tear should alert surgeons to the potential presence of a medial meniscal ramp lesion.