Introduction:
Total knee arthroplasty (TKA) is associated with severe pain. We examined whether an ultrasound-guided, single-injection L2 erector spinae plane block could improve analgesia compared to an ultrasound-guided iPACK (infiltration between the popliteal artery and capsule of the knee) block with adductor canal block (ACB) in patients undergoing TKA under spinal anesthesia.

Material and methods:
Ninety patients aged 65–89 years of both sexes (ASA I–III) scheduled for TKA were randomly allocated to receive iPACK block (ropivacaine 0.2%, 20 mL) with ACB (ropivacaine 0.2%, 10 mL), lumbar erector spinae plane block (L-ESPB) (ropivacaine 0.2%, 20 mL on each side), or to the control group. The primary outcome was total opioid consumption. The secondary outcomes included pain scores, time to first rescue opioid analgesia, quadriceps muscle strength, neutrophil-to-lymphocyte ratio (NLR), and platelet- to-lymphocyte ratio (PLR).

Results:
The total opioid consumption in 48 h was significantly lower in the iPACK+ACB group (mean ± SD) (3.0 ± 3.3) compared to L-ESPB (6.8 ± 3.8, P = 0.0442) and the control group (18.2 ± 4.0, P < 0.001). The time to first rescue opioid analgesia was longer in the iPACK+ACB (12.0 ± 1.9) compared to the L-ESPB (9.2 ± 1.9, P < 0.001) group and the control group (4.3 ± 1.1, P < 0.001). The pain scores, NLR, and PLR levels were significantly lower in the iPACK+ACB and L-ESPB groups than at all time points in the control group.

Conclusions:
The iPACK+ACB is more effective than L-ESPB in pain management following TKA. iPACK+ACB and the L-ESPB lowered total opioid consumption and prolonged time to first opioid analgesia. NLR and PLR levels did not differ between the groups.