Correlation Between Medial Meniscal Extrusion Determined by Dynamic Ultrasound and Magnetic Resonance Imaging Findings of Medial‐Type Knee Osteoarthritis in Patients With Knee Pain

Objectives The aim of our study was to investigate the relationship between medial meniscal extrusion (MME) determined by dynamic ultrasound (US) and magnetic resonance imaging findings of medial-type knee osteoarthritis (OA). Methods Single knees of 102 patients with knee pain were assessed by radiography, dynamic US, and magnetic resonance imaging. All knee radiographs were interpreted and grouped according to the Kellgren-Lawrence (KL) scale. Medial meniscal extrusion in non-weight-bearing and weight-bearing positions and the difference of these values (ΔMME) were measured by dynamic US. The medial tibiofemoral compartments of all knees were evaluated and grouped according to the Whole-Organ Magnetic Resonance Imaging Score (WORMS). Mean values of non-weight-bearing MME, weight-bearing MME, and ΔMME ± standard deviations for groups formed according to the KL scale and WORMS system were compared. Results We demonstrated that different from non-weight-bearing MME, weight-bearing MME was significantly correlated with not only high grades but also lower grades of cartilage damage and subchondral bone marrow lesions in medial-type knee OA. Although the difference in non-weight-bearing MME between cartilage status groups 1 and 2 was not significant (P = .071), there were significant differences in of weight-bearing MME between groups 1 and 2, between groups 2 and 3, and between groups 3 and group 4 (P = .003, .002, and .032, respectively). Conclusions We found statistically significant associations between MME values and the severity of the OA findings according to both the KL scale and WORMS system. We offer dynamic US as an initial tool for the diagnosis and a screening method to estimate the severity of knee OA.