Even though the ACB is mainly a sensory nerve block, a study in healthy volunteers showed a small decline by 8% in quadriceps muscle strength(10). It is speculated that the decline in muscle strength was caused by the spread of local anesthetic to the nerve supplying the vastus medialis of the quadriceps femoris muscle. Three out of eleven of the volunteers experienced an even larger decline of 25 % in quadriceps muscle strength. It has been argued that this decline likely was caused by a proximal spread of the local anesthetic to the femoral triangle thereby resulting in an affection of the femoral nerve. In this study, a volume of 30 ml of local anesthetic was used.