Patients will be randomised 1:1 using sealed envelope technique into two groups of 88 each and study drug will be prepared by an anaesthesiologist not involved in the study. Group A (n=88) will receive 12.5mg (2.5 ml) of 0.5% hyperbaric levobupivacaine and fentanyl 25 mcg (0.5 ml) while Group B (n=88)  will receive 12.5mg (2.5 ml) of 0.5% hyperbaric bupivacaine and fentanyl 25 mcg (0.5 ml).

Thorough pre�’anesthesia check�’up will be done a day prior to surgery that is, detailed history, general physical examination, systemic examination, airway assessment and lumbar spine examination. Patients will be kept nil by mouth 6 hours for light meal and 2 hours for clear fluids before surgery. The anaesthesia plan will be  explained to the patients.

No premedication will be administered. Hemodynamic parameters will be recorded with ECG, systolic and diastolic blood pressure, heart rate and oxygen saturation (SpO2). Intravenous prehydration with 500 ml of 0.9% isotonic NaCl infusion will be administered. Hypotension, defined as a decrease of systolic blood pressure more than 20% from baseline or a fall below 90 mmHg, will be treated with intravenous doses of 3mg of ephedrine and intravenous fluid as required, and bradycardia, defined as heart rate below 50 beats/min, will be treated with 0.3–0.6mg of intravenous atropine. 

Patients will be placed on the operation table in the sitting position and will be administered 3 ml (60mg) 2% lidocaine infiltration anesthesia through L3–4 after sterilization with antiseptic solution (povidone iodine). The intrathecal space will be reached with a standard Quincke spinal needle of appropriate size. 

Non traumatic pin prick in the mid clavicular line with a blunt needle will be used for sensorial block evaluation (onset, offset) and sensorial block reversal time.

Bromage scale will be used for assessment of the intensity of motor block. In the Bromage scale, the intensity of motor block is assessed by the patient’s ability to move their lower extremities as follows: 0=free movement of legs and feet; 1=just able to flex knees with free movement of feet; 2=unable to flex knees, but with free movement of feet; and 3=unable to move legs or feet.

Onset of motor block  is recorded as when Bromage scale is ‘1’ after administration of local anesthetics, and ‘onset of highest motor block’ is recorded as time to reach the highest scale of motor block that is Bromage scale 3. ‘Operation duration’ is recorded as time until end of operation after administration of local anesthetics. 

The hemodynamic parameters [systolic, diastolic blood pressure, mean blood pressure, heart rate and oxygen saturation (SpO2)] were recorded at 0 and every 10 min after injection of local anaesthesia.

Side effects like hypotension, bradycardia, shivering, nausea and vomiting will be followed-up 24 hour postoperatively.