Side-Effect Profiles And Efficacy Of Low Dose Intrathecal Morphine Combine With Periarticular Injection In Elective Primary Unilateral Total Knee Arthroplasty

BACKGROUND: Total knee arthroplasty (TKA) is concerned as a severe postoperative pain procedure. Intrathecal morphine provides good analgesia but has many side effects such as nausea, vomiting, pruritus and respiratory depression. Appropriate postoperative pain control strategy with lower side effect is still challenging. We combined periarticular injection(PI) as a multimodal analgesia with intrathecal morphine in order to decrease intrathecal morphine dosage and lower side effects. OBJECTIVE: To determine side-effect profiles and efficacy of 0.1 mg and 0.2 mg intrathecal morphine combine with PI in primary unilateral TKA. MATERIAL AND METHOD: In this prospective, double-blinded, randomized controlled trial. Patients undergoing TKA were recruited from April 2018 to April 2019. All patients were randomized into 3 groups. M 0 (n=32), M 1 (n=36)and M 2 (n=34) represent no intrathecal morphine, 0.1 mg and 0.2 mg intrathecal morphine respectively. All Group received same regimen of PI as a multimodal analgesia and same postoperative pain control protocol. RESULTS: Patients in group M 2 had more nausea or vomiting side effects compared to group M 1 in early postoperative 4 hours(77.1% and 51.4%) with statistical significant(p<0.05) and also required 2 antiemetic drug to relieve symptoms (4.7% and 2.3%) with statistical significant ( p<0.05). No difference in postoperative pain score, rescue analgesic drug consumption ,pruritic score, sedation score, respiratory depression and orthopedic outcomes such as straight leg rising time and maximum active knee flexion between M 1 and M 2 groups. CONCLUSION: Lower intrathecal morphine dosage (0.1 mg) combine with periarticular injection in primary unilateral total knee arthroplasty provide similar postoperative pain control as standard intrathecal morphine dosage(0.2 mg) combine with periarticular injection with lower rates and severities of nausea and vomiting in first postoperative 4 hours.