Dynamic ultrasound reveals the specific behavior of the medial meniscus extrusion in patients with knee osteoarthritis

Abstract Background In the dynamic condition, knee osteoarthritis (OA) usually presents with pain. In the weight-bearing condition, a medial meniscus extrusion (MME) may cause severe symptoms and pathological progression. However, the correlation between a dynamic MME and pain has not been elucidated. Now, an MME can be evaluated under dynamic conditions and reflect the characteristics of symptomatic knee OA. This study investigated MMEs during walking and their correlation with knee pain. Methods Thirty-two symptomatic patients with knee OA (mean age, 60.5 ± 9.9 years) were enrolled in this study. The medial meniscus was evaluated using ultrasonograms during walking, and in the static supine and unipedal standing positions, as dynamic and static conditions, respectively. The ΔMME (the difference between the maximum and minimum MMEs) was obtained in each condition. The intensity of the knee pain during walking was measured by the visual analog scale (VAS). Results The ΔMME in the dynamic condition was significantly higher than that in the static condition (P