Comparison of local anesthetic infiltration to continuous femoral nerve block for post-operative analgesia in total knee replacement patients

Objective: This study compared post-operative analgesic efficacy, morphine consumption, mobilization time and complications of a continuous Femoral Nerve Block (FNB) with Local Infiltration Anesthesia (LIA).s

Material and methods: 60 patients scheduled for unilateral total knee replacement under spinal anesthesia, were randomly allocated in two groups FNB and LIA group. FNB group received bolus dose of drug-containing 20 ml of 0.5% levo bupivacaine plus 50 μg of dexmedetomidine plus 80 μg of fentanyl and in post-operative period an infusion of 0.2% ropivacaine was started of 7 ml per hour while LIA group received a mixture of 100 ml prepared by adding 40 ml 0.5% levo bupivacaine plus 60 mg ketorolac plus 15 mg morphine plus normal saline and given in 2 injections. Postoperative pain severity was measured by using VAS scale, rescue analgesia and mobilization time was also recorded.

Result: LIA group had significantly low VAS pain score at 4, 8, 12 and 24 hours postoperatively as compared to FNB group, the mean morphine consumption in LIA group was significantly less 21.06 ± 10.88, LIA 8.16 ± 10.38, p-value <0.001), also in LIA group more than 95% patients were able to do straight leg raising and were able to move with help at 24 hours postoperatively against only 60% patients in FNB group.

Conclusion: LIA is a newer multimodal analgesic method that gives excellent pain control decreases morphine consumption and preserves quadriceps muscle function thereby improving patient satisfaction which plays a vital role in early ambulation and reducing complications.