The aim of this study is to assess the qualitative and quantitative variations of the strength, work and fatigue of the thigh muscles after ACL surgery. The reference is the preoperative assessment (V1), the variation is measured on V2 (measurements at 3 months) and V3 (measures at 9 months). Each patient is his own control. In addition, a control group of healthy subjects is used to determine level of significance of each parameter.