The purpose of this study was to assess VM muscle elasticity during QS and to investigate its relationship with knee extensor strength in patients following ACL injury. The purpose of this study was to assess VM muscle elasticity during QS and to investigate its relationship with knee extensor strength in patients following ACL injury.
Twenty-six ACL-deficient patients participated in the study. VM muscle elasticity was measured during QS using SWE at the midpoint of the VM. Isokinetic concentric knee extensor strength was measured at 60°/s. In addition, the limb symmetry index (LSI) of VM muscle elasticity during QS and knee extensor strength was calculated using the values from the affected and the unaffected side (affected side / unaffected side*100). Wilcoxon signed-rank test was used to compare the affected and the unaffected side for VM muscle elasticity during QS and knee extensor strength, respectively. Spearman correlation was used to assess relationships between the LSI of VM muscle elasticity during QS and the LSI of knee extensor strength.
VM muscle elasticity during QS was 92.8±54.2 kPa of the unaffected side, 60.3±50.8 kPa of the affected side, and LSI was 66.1±32.5%. The Knee extensor strength was 218.0±68.4 Nm/kg of the unaffected side, and 160.9±67.6 Nm/kg of the affected side, and LSI was 74.6±21.5%. VM muscle elasticity during QS and the knee extensor strength of the affected side were both significantly lower than those of the unaffected side. In addition, LSI of VM muscle elasticity was positively associated with LSI of knee extensor strength.
After ACL injury, VM muscle elasticity during QS of the affected side was lower than on the unaffected side, and VM muscle elasticity during QS was a factor related to knee extensor strength.
Recovery of VM muscle elasticity during QS may be necessary in patients following ACL injury.
quadriceps setting
muscle elasticity
