Intrathecal Morphine Use Improves Postoperative Analgesia and Reduces Opioid Consumption in Patients Undergoing Total Knee Arthroplasty Under Spinal Anesthesia: A Retrospective Study

Comparative efficacy of intrathecal morphine and adductor canal block in the knee arthroplasty population: a retrospective multi-centre cohort study

BACKGROUND

Finding the balance of good postoperative analgesia while facilitiating mobility is important for a safe and satisfactory patient experience during Total Knee Arthroplasty (TKA). This study aimed to compare the efficacy of intrathecal morphine, adductor canal block, and their combination in optimizing pain management and postoperative recovery in TKA patients. This retrospective analysis of prospectively collected data evaluated 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. They 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. Group BM patients received both ACB and ITM.

RESULTS

Patients who received an ACB had faster postoperative mobilization compared to those without (p < 0.001). Patients in Group BM had the lowest pain scores at rest (Visual Analogue Scale (VAS) 2.9) and with movement (VAS 5.3), while Group B patients experienced the highest pain scores at rest (VAS 3.7) and on movement (VAS 6.5) (p = 0.005). Patients who received ITM had the lowest opioid requirements (p < 0.001). There was no significant differences 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 mobilization compared with ACB or ITM alone.

Effects of Intrathecal Morphine Administration in Patients Undergoing Primary Total Hip Arthroplasty Under Spinal Anesthesia With Quadratus Lumborum Block for Postoperative Analgesia

Introduction Quadratus lumborum (QL) block has previously been shown to provide improved analgesia in patients undergoing primary total hip arthroplasty (THA) under spinal anesthesia when compared to spinal anesthesia alone. Additionally, recent studies have shown the addition of intrathecal morphine (ITM) to provide superior postoperative analgesia in patients undergoing various surgical interventions including total knee arthroplasty under spinal anesthesia with peripheral nerve blockade. At this time, however, there has not been a study evaluating the effects of intrathecal morphine in patients undergoing THA under spinal anesthesia with QL block. This study aims to assess if the addition of intrathecal morphine can provide adequate or even superior postoperative analgesia in patients undergoing primary THA. Methods This retrospective study included 26 patients in the spinal/QL block/intrathecal morphine (SA+QLB+ITM) group, 31 patients in the spinal/QL block group (SA+QLB), and 28 patients in the spinal only (SA or control) group. Twenty-six patients undergoing primary THA under a combination of spinal anesthesia and peripheral nerve blockade (quadratus lumborum block) were given a dose of 100 mcg of intrathecal morphine. Various parameters were evaluated including Post-Anesthesia Care Unit (PACU) and 24-hour visual analog scale (VAS) scores, time to first opioid use, 24- and 48-hour total opioid use as oral morphine equivalents (OME), 24-hour ambulation distance, and time from block placement to hospital discharge. The results were analyzed and compared to patients undergoing primary THA under spinal anesthesia with QL block (no intrathecal morphine) and compared to a control group of patients undergoing primary THA under spinal anesthesia only. Results The study analysis included 26 patients in the SA+QLB+ITM group, 31 patients in the SA+QLB group, and 28 patients in the SA (control) group. When compared with the control group, the SA+QLB+ITM had lower 24-hour total opioid usage (mean difference 20.80 OME, CI 6.454 to 35.15, p-value 0.0025), longer time to 1st opioid use (mean difference -20.51 hours later, p-value .0052), lower 24-hr VAS (difference 2.421, p-value 0.0012, CI 0.8559 to 3.987), and faster time to discharge (16.00 hr earlier, p-value 0.0459). When compared to the SA+QLB group, the SA+QLB+ITM group only showed a statistically significant difference in faster time to discharge (19.46 hr earlier, p-value 0.0068). However, while there was no statistically significant difference in time to 1st opioid use between the control and SA+QLB group, the difference did become significant when comparing the control to the SA+QLB+ITM group (mean difference -20.51 hours later (p-value .0052). There was no significant difference in either of the three groups in ambulation distance at 24 hours, PACU VAS, or 48-hour total opioid use. Conclusion Our study concludes that the addition of 100 mcg ITM for total hip arthroplasty under spinal anesthesia improved postoperative analgesia compared to the control group. Also, the ITM group did better with respect to delay in first opioid use and decreased hospital stay compared to the control and block-only groups. Our study warrants no more concerns of PONV, pruritus, or respiratory depression with this dose of ITM and requires standard postoperative care.

The Dose Comparison of Intrathecal Morphine for Postoperative Analgesia in Total Knee Arthroplasty Under Spinal Anesthesia: A Single Institute Retrospective Study

Background and purpose of the study Intrathecal morphine (ITM) provides effective postoperative analgesia in patients undergoing total knee arthroplasty (TKA) under spinal anesthesia. However, the ideal dose at which maximal analgesic effects can be delivered with minimal side effects is not clearly known. This retrospective study is aimed to compare two different doses of ITM with respect to analgesia benefits and side effects. Methods This is a retrospective, descriptive, single-center study approved by the Institutional Review Board (IRB) at the University of Alabama at Birmingham. Three patient groups were selected: a control group receiving continuous adductor canal block (CCACB) under spinal anesthesia, and two experimental groups receiving single-dose adductor canal block (SSACB) under spinal anesthesia with either 100 mcg or 150 mcg of ITM. The sample size included 75 patients (25 per group) who were 18 years and older, American Society of Anesthesiology (ASA) class 1-3 who were undergoing primary TKA. Patients with chronic pain or opioid use exceeding 30 days and those undergoing surgeries other than primary TKA were excluded. Outcome data, including opioid use (from which post-operative oral morphine equivalents (OME) were calculated), antiemetic use, visual analog pain scale (VAS) scores, distance ambulated at 24 hours, and length of hospital stay, were extracted by chart review. Results In the post-anesthesia care unit (PACU), patients in both ITM groups experienced significantly lower opioid consumption and pain scores compared to the control group (p<.001). Furthermore, cumulative OME at 24 hours was significantly less in the ITM groups compared to the control, but there was no difference between ITM doses (p=0.004; mean cumulative OME for control was 77.2 OME vs 43.4 OME for 100 mcg ITM vs 42.6 OME for 150 mcg ITM). Antiemetic usage did not increase in the ITM groups. Although there was no statistically significant difference in ambulation at 24 hours, both ITM groups exhibited a trend toward greater average ambulation distance compared to the control group (p=0.095; mean distance walked for control was 67.6 feet, 76.6 feet for 100 mcg ITM vs 98.8 feet for 150 mcg ITM). Hospital length of stay did not significantly differ between the groups. Conclusion ITM doses of 100 mcg and 150 mcg provide effective analgesia for patients undergoing lower extremity total knee arthroplasty under spinal anesthesia. Patients receiving ITM had better pain scores in the immediate post-operative period and had overall less oral morphine equivalent consumption when compared to control. In addition, the safety and side effect profile for ITM is similar for both doses as there was no incidence of respiratory depression and antiemetic usage did not differ between all study arms. Future studies should explore the use of higher ITM doses and consider a broader patient population to further understand the advantages and potential drawbacks of ITM in TKA surgery.