Opioid consumption in total knee arthroplasty patients: a retrospective comparison of adductor canal and femoral nerve continuous infusions in the presence of a sciatic nerve catheter.

OBJECTIVE: To compare opioid consumption among patients who receive a continuous adductor canal block (ACB) versus continuous femoral nerve block (FB) for total knee arthroplasty analgesia in the presence of an intermittent sciatic nerve catheter (iSB).

DESIGN: Matched cohort retrospective study.

SETTING: Mayo Clinic, Jacksonville, FL.

PATIENTS: Ninety patient charts were included in this study: 45 patients with continuous ACB/iSB and 45 with continuous FB/iSB. Patients were matched according to mean preoperative opioid consumption and pain scores, BMI, age, and gender.

MEASUREMENTS: The primary outcome of the study was postoperative on-demand opioid consumption on postoperative days 0 (POD 0), 1 (POD 1), and 2 (POD 2). Secondary outcomes included postoperative Visual Analog Scale (VAS) scores for anterior and posterior knee pain, incidence of nausea and pruritus, need for intravenous rescue opioid, and need for catheter bolus by a physician.

MAIN RESULTS: On POD 0, mean opioid consumption in milligrams of oral morphine equivalent [mean±SD (95% CI)] was 43.98mg±33.36 (33.96, 54) in the ACB/iSB group vs 38.45mg±30.99 (29.14, 47.76) in the FB/iSB group, respectively (P=.42); on POD 1, 74.96mg±37.23 (63.78, 86.14) vs 72.40mg±62.34 (53.67, 91.13) (P=.81); on POD 2, 28.19mg±17.69 (22.87, 33.51) vs 31.84mg±23.09 (24.90, 38.78) (P=.40). On POD 1, median anterior knee VAS scores at rest were equivalent in both the ACB/iSB and FB/iSB groups (1 vs 1, respectively, P=.46); however, patients in the ACB/iSB group were more likely to have higher anterior knee pain scores with movement (4 vs 1, P=.002).

CONCLUSION: In the first 2 days after a total knee arthroplasty, opioid consumption in patients with continuous ACB/iSB was not significantly different from patients receiving continuous FB/iSB. Continuous adductor canal block appears to provide adequate analgesia when compared to continuous femoral blockade.