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Abstract
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Background and Aims Motor-sparing peripheral nerve blocks, like Adductor Canal Block (ACB) and Femoral Triangle Block (FTB), enhance multimodal opioid-sparing strategies after total knee arthroplasty. Incorporating a Popliteal Plexus Block (PPB), targeting genicular nerves from the tibial and obturator nerve, may further optimize these strategies. We hypothesized that a combination of PPB+FTB could reduce 24-hour opioid consumption(=primary outcome) after total knee arthroplasty in comparison to standalone FTB and standalone ACB.
Methods In this patient- and assessor blinded study, 165 patients were randomized into three parallel intervention groups, receiving either 1)PPB+FTB, 2)FTB or 3)ACB. Preoperatively, maximum voluntary isometric contraction and manual muscle test of knee and ankle movement were assessed before and after nerve block procedure. Postoperatively, opioid consumption and pain scores were obtained for 24 hours, and mobilization assessed at 5 hours. Intravenous oxycodone was administered via patient-controlled analgesia pumps.
Results At 24 hours postoperatively, consumed intravenous oxycodone varied significantly between groups(P<0.009), with medians(IQR) of 6 mg(2-12) in the PPB+FTB group, 10 mg(8-16) in the FTB group, and 12 mg(6-18) the ACB group. Median consumption in the PPB+FTB group was reduced by -4 mg(95%CI[-7.4, -1.0],P<0.005) and -6 mg(95%CI[-8.3, -1.3],P<0.012) compared to groups of FTB and ACB, respectively. No differences were found in pain scores, mobilization, or muscle strength. Post-hoc analysis revealed 12 PPB+FTB patients not requiring opioids at 24 hours postoperatively, compared to only 2 FTB and 6 ACB patients.
Left: The curved transducer’s location is marked by a black line on a slightly outwardly rotated right thigh, around 2-5 cm proximal to base of the patellae. Right: Ultrasonic picture of Popliteal Plexus Block. Orange line = The needle, inserted medially to the transducer and advanced using an in-plane technique, piercing the sartorius muscle. Endpoint for injection of 10 mL local analgesic is on top of the femoral artery, ensuring a spread anterolaterally to the artery. FA = femoral artery, FV = femoral vein, SaM = sartorius muscle, VMM = vastus medialis muscle, AMM = adductor magnus muscle
Conclusions Adding PPB reduced 24-hour postoperative opioid consumption but not pain scores. PPB did not hinder mobilization or increase the risks of motor impairment.