Postoperative Ultrasound Guided Continuous Femoral Nerve Blockade for Unilateral Total Knee Arthroplasty: A Comparison of 0.125% Bupivacaine and 0.2% Ropivacaine.

Context: Total knee arthroplasty (TKA) is associated with severe postoperative pain which increases morbidity and mortality.

Aims: The aim of the study was to compare the analgesic efficacy and motor blockade of continuous infusion of 0.125% bupivacaine and 0.2% ropivacaine in femoral nerve block following unilateral TKA and to assess the effectiveness of femoral nerve block.

Settings And Design: One hundred and fifty patients undergoing unilateral total knee replacement surgery were included in this prospective observational comparative study.

Subjects And Methods: Patients are divided into two groups of 75 each. Femoral nerve catheter was placed at the end of surgery using ultrasound. Postoperative analgesia and motor blockade were compared for the next 24 h using visual analog scale (VAS) score, additional analgesic requirement, and Bromage scale.

Statistical Analysis: Student's -test and Chi-square test were applied.

Results: There was no statistically significant difference in pain between the two groups though VAS score (during rest and movement) and opioid consumption were lower in bupivacaine group. Nearly 28.6% patients experienced pain and required additional analgesics. Seventy-two percent among them complained of pain in the popliteal region supplied by sciatic nerve. Eight patients excluded from the study also had pain in the popliteal fossa. There was a statistically significant difference in motor blockade between the two groups at 12, 18, and 24 h after starting infusion. Bupivacaine group had a higher percentage of type three blocks compared to ropivacaine group.

Conclusion: Continuous femoral nerve block (CFNB) with 0.125% bupivacaine infusion provided better analgesia with denser motor blockade compared to 0.2% ropivacaine infusion. CFNB alone is not sufficient to provide adequate analgesia following unilateral TKA.