Treatment groups Treatment details Femoral Group (40 patients) Continuous femoral nerve block (bolus: 0.5% Ropivacaine 10-15 ml ; infusion of 0.15 % Ropivacaine 4-6ml/h) Adductor Group (40 patients) Adductor canal block with steroid adjuvant (bolus: 0.5% Ropivacaine 10-15ml; Dexamethasone 4mg) (Total 80 patients will be recruited)