The effect of graded knee brace at two angles of 60 and 30 degrees on the frequency spectrum of ground reaction forces in individuals with genu valgum during landing

Background: Genu valgum is a postural malalignment in the knee joint. This malalignment is accompanied by altered mechanical forces in the tibiofemoral and patellofemoral joints. The purpose of this study was to investigate the effect of using a graded knee brace in two angles of 60 and 30 degrees on the frequency spectrum of ground reaction forces in individuals with genu valgum during landing.

Methods: The present study was semi-experimental. Twenty non-athlete male students with genu valgus (age range: 20-30 years) were volunteered to participate in the study. The landing task was done during three conditions including without a knee brace, with a brace at two 30 and 60 degrees of flexion from a height of equal to 30 cm. Bertec force plate was used to record ground reaction forces. Fourier transform was used to calculate ground reaction force-frequency content during both landing conditions with and without a knee brace.

Results: The results of this study showed a significant reduction in the frequency content with a power of 99.5% in the mediolateral direction (P=0.02; high effect size) and vertical direction (P=0.075; high effect effect) during landing with a knee brace at 60 degrees of flexion angle compared with without knee brace condition. Also, the median frequency component in the mediolateral direction (P=0.019; low effect size) and in the anterior-posterior direction (P=0.019; high effect effect) showed a significant decrease during wearing a knee brace compared with without it.

Conclusion: Regarding the decreasing of median frequency after using the knee brace, it might be effective in the reduction of injury rate in individuals with genu valgum. However, further study warranted to better establish this issue.