Comparison of Combined Intrathecal Morphine and Sonar-guided Singleshot Femoral Nerve Block vs. Either Technique Alone for Postoperative Analgesia in Patients Undergoing Total Knee Replacement Surgery

Abstract

IntroductionEnd stage knee arthritis is commonly treated with total knee replacement (TKR). As the population ages, the frequency of this surgery proportionally increases [1] bringing with it the challenge of managing older patients with frequent comorbid diseases and increased risk of complications. Poorly controlled pain immediately after surgery is still a key issue for this procedure that may influence the patient's participation in physiotherapy, time to discharge from hospital, and the long-term outcome. Optimal postoperative analgesia can lead to early mobilization, ambulation, and return to a normalized gait pattern. Traditionally, this has been managed by epidural analgesia, peripheral nerve blocks and parenteral or spinal opioids [2]. Multimodal analgesia protocols for TKR have been effective in decreasing requirements for narcotic medications in the early postoperative period. Consequently, decreasing the opioid adverse effects that can slow down rehabilitation such as nausea, vomiting, hypotension, respiratory depression, and constipation [3,4].The efficacy of femoral nerve block (FNB) as a part of a multimodal analgesic protocol has been well documented [3][4][5][6]. FNB has been shown to decrease opioid use, improve postoperative pain scores, and decrease length of stay while avoiding many of complications associated with other techniques such as continuous epidural analgesia or intrathecal opioids [6]. We hypothesized that the combination of single-shot ultrasound-guided FNB and low dose intrathecal morphine (0.2 mg ITM) would improve the quality of postoperative pain control and decrease side effects of systemic opioid use. So, we designed this study to demonstrate the additive effect of combined femoral nerve block (FNB) and 0.2 mg intrathecal morphine (ITM) compared with either technique alone for postoperative analgesia in patients undergoing unilateral (TKR) under spinal anesthesia.

Intrathecal morphine versus femoral nerve block for pain control after total knee arthroplasty: a meta-analysis

“…A total of 308 papers were reviewed, and 209 papers were removed according to the inclusion criteria at abstract and title levels. Ultimately, five clinical studies with 225 patients (ITM group = 114, FNB group = 111) were included in this meta-analysis [ 8 , 12 – 15 ].…”

“…However, several disadvantages existed in that meta-analysis. First it ignored important randomized controlled trials (RCTs), which may have had an important influence on the final results [ 8 ]. Furthermore, continuous FNB and single-shot FNB were not compared in a subgroup analysis.…”