Dynamic response of medial meniscus extrusion to the lateral wedge insole is correlated with immediate pain reduction in knee osteoarthritis patients: real-time ultrasonographic study

Purpose To investigate the effect of lateral wedge insole (LWI) on medial meniscus extrusion (MME) observed during dynamic evaluation with ultrasound and its correlation with the alteration in knee pain in patients with knee osteoarthritis (OA). Methods This cohort study included 25 participants with knee OA. The medial meniscus was imaged during walking in video mode using ultrasonography. The degree of increase in MME (Delta MME) was calculated as the difference in the value of the maximum and minimum MME. The intensity of knee pain was evaluated immediately after the walking trial using the visual analogue scale (VAS). These measurements were performed with and without the LWI. The participants were categorised into the responder group, which was identified by the constant reduction in the VAS, and the non-responder group. Results MME, Delta MME, and knee pain during walking were significantly lower with the LWI than without the LWI (p < 0.01). The reduction in Delta MME with the LWI in the responder group was significantly higher than that in the non-responder group (p < 0.01). Conclusions Our findings showed that MME and knee pain during walking decreased with LWI use, especially in patients whose reduction in knee pain was characterised by inhibition in the increase in MME observed during dynamic evaluation with ultrasound.