age (50 80 yrs) with monofilament test 10 g (> 4/8)

refusal of sciatic nerve block,

age < 50 yr or > 80 yr,

american society of anesthesiologists state > iv,

presence of contraindications to local anaesthesia (known allergy to local anaesthetics, sepsis),

emergency surgery,

patients unlikely to be fully cooperative during the study,

psychiatric disorders, or

those abusing alcohol or drugs, and

participation in another study within the previous 30 days. moreover, patients with preoperative estimated values of creatinine clearance < 50 ml min-1 (cockroft and gault formula) or with glycosylated hemoglobin (a1c) level > 8 % or with type 1 diabetes mellitus (insulin therapy)