Comparative Efficacy of Intrathecal Morphine and Adductor Canal Block in the Knee Arthroplasty Population: A Retrospective Multi-Centre Cohort Study

Abstract

Background Finding the balance of good postoperative analgesia while facilitating mobility is important for a safe and satisfactory patient experience during Total Knee Arthroplasty (TKA). This retrospective study evaluated different anaesthetic techniques in patients undergoing TKA to assess postoperative pain scores, time to mobilisation, and length of hospital stay. Methods 1006 consecutive patients undergoing elective TKA across two large tertiary centres were included over six years. There were divided into one of four groups according to the type of analgesia received: Group N patients received no neuraxial morphine or regional block, Group B patients received adductor canal block (ACB) only, Group M patients received intrathecal morphine (ITM) but no regional block, and Group BM were patients who received both ACB and ITM. Results Patients who received an ACB mobilised earlier compared to patients without a block (p < 0.001). Patients in Group BM had the lowest pain scores at rest and with movement, while Group B patients experienced the highest pain scores at rest and on movement (p = 0.005). Patients who received ITM had the lowest opioid requirements (p < 0.001). There was no significant difference between groups in requirement for rescue pain management strategies (p = 0.06). Conclusions The combination of ITM and ACB in patients undergoing TKA provides improved postoperative analgesia with lower postoperative opioid requirement and earlier mobilisation compared with ACB or ITM alone.