Effect of insoles with different cushioning properties on knee impact after radial tear of posterior horn of medial meniscus: a finite element analysis

The posterior horns of the medial menisci are more commonly injured during exercise. Cushioning insoles are one of the most widely used conservative interventions for preventing knee joint injuries. However, the effect of the cushion property of insoles on the knee joints with meniscal tears remain unknown. We investigated the effects of insoles with different cushioning properties on the knee joint following a radial tear of the posterior horn of the medial meniscus. Full extension landing with a heel-first strike pattern was performed by 12 participants randomly wearing ethylene vinyl acetate (EVA) and artificial cartilage foam (ACF) insoles, and the peak plantar pressures (pPP) were measured. The right knee of the participant whose pPP was closest to the median was loaded to a finite element model with radial tear. The pPP of EVA insoles (2386.42 ± 298.29 N) was higher than that of ACF (2174.16 ± 270.63 N) (t = 7.84, P < 0.001). The finite element analysis revealed that the peak von Mises Stress (pVMS) values of the medial and lateral menisci were 12.32 MPa and 7.90 MPa for injured joint with EVA, and 9.02 MPa and 6.84 MPa for injured joint with ACF. Hence, insoles with higher cushioning can decrease the vertical impact force and stress concentration of the knee joint after radial tear of the posterior horn of the medial meniscus.