Meniscal Extrusion Correlates with Symptom Severity in Knee Osteoarthritis: An Ultrasound and Magnetic Resonance Imaging Analysis of 100 Patients

Purpose: The aim of this study was to investigate how meniscal extrusion, assessed either with ultrasounds or magnetic resonance (MR), correlates with clinical symptoms in knee osteoarthritis (OA). Methods: One hundred patients with symptomatic knee OA were enrolled (60.3 ± 9.7 years). Patients underwent MR evaluation and ultrasound analyses (clinostatic and orthostatic positions). Patients were clinically evaluated through IKDC, KOOS, WOMAC, VAS, and Tegner scores. Correlation analyses were performed between meniscal extrusion extent and clinical scores. Lower (<4 mm) and higher extrusion (≥4 mm) groups were also compared. Results: The identification of low/high extrusion was 56/44 (MR) and 45/55 (ultrasounds) for patients with medial meniscus and 72/28 (MR) and 57/43 (ultrasounds) for patients with lateral meniscus. Meniscal extrusion correlated with symptoms (p < 0.05) with worse clinical findings in patients with higher extrusion, particularly for the lateral meniscus. For the medial meniscus, more differences were found between lower and higher extrusion groups with ultrasounds than MR, especially in the orthostatic position, while for the lateral meniscus, similar trends were documented with both methods. Conclusions: Extrusion of both menisci correlates with knee OA symptoms, with a stronger correlation for the lateral meniscus. Ultrasounds performed in the standing position identify more patients with meniscal extrusion and correlate better than MR with clinical findings.