Discussion
delirium, vascular injuries, postoperative pain, nausea, femoral neck fractures, quadriceps motor block, infections, quadriceps weakness, pain, dizziness, infection, fractures, quadriceps motor weakness, femoral head necrosis
DEEP VENOUS THROMBOSIS, ADVERSE EVENTS, HIP OSTEOARTHRITIS, INFECTIONS, ADVERSE EFFECTS, SECONDARY, INFECTION, COMPLICATIONS
IPB is a promising motor-sparing analgesic technique that selectively targets the sensory branches of the hip joint originating from femoral nerve and accessory obturator nerve [The basis for postoperative analgesia for hip arthroplasty lies in the innervation of hip joint. Most nociceptors of the hip joint are situated in the anterior capsule, suggesting that this is the primary site for postoperative analgesia [Optimal regional analgesia following hip arthroplasty should not only minimize postoperative pain but also maximize motion retention to accelerate recovery and rehabilitation. In this study, the IPB group demonstrated better quadriceps strength retention over the first 24 h after surgery. Greater quadriceps strength facilitates early functional rehabilitation training, leading to fewer complications and quicher recovery. Our findings indicated that the first time out of bed was shortened in the IPB group, likely due to better retention of quadriceps strength. However, it’s important to note that IPB did not entirely avoid the motor block of the quadriceps. For instance, upon arrival at PACU, the quadriceps strength of some patients was no more than an MMT grade 4 out of 5. By 6 h after surgery, all patients in the IPB group demonstrated quadriceps strength was ≥ MMT grade 4 out of 5, sufficient for functional exercise out of bed. We speculate that the initial decline of quadriceps strength might be due to residual anesthetic effect upon arrival at PACU. In contrast, patients in the FNB group showed persistent quadriceps motor block at 6 h after surgery. Most of these patients had quadriceps strength of MMT grade 2 to 3 out of 5, potentially limiting functional exercise out of bed. A recent study found that IPB with 1.8% lidocaine (5 ml) did not significantly reduce the maximal force of knee extension [There were no nerve or vascular injuries and infections related to nerve block observed in this study. Similarly, there were no differences between the two groups in terms of dizziness, nausea and vomiting, delirium, deep venous thrombosis and falls in-hospital. One falls in-hospital occurred in the FNB group, while none was observed in the IPB group. This fall might be attributed to quadriceps motor weakness caused by FNB. Although the incidence of falls in-hospital was low, we must remain vigilant about the potential adverse events due to quadriceps weakness.There are several limitations in this study that should be considered when interpreting the results. First, the study population included patients undergoing hip arthroplasty due to a variety of conditions, including femoral neck fractures, femoral head necrosis, and hip osteoarthritis. The heterogeneity of this patient population could have introduced additional variability into the results, potentially reducing the likelihood of observing significant differences between groups. Future research may benefit from focusing on a more homogenous population, such as patients with hip fractures or those with non-inflammatory degenerative joint diseases like osteoarthritis.Second, patients underwent both total hip arthroplasty and hip hemiarthroplasty were included in this study. This also adds heterogeneity and may have further reduced our ability to observe intergroup differences. Future studies might benefit from separately these surgical procedures. Third, patients in both the IPB and FNB groups reported relatively low pain levels postoperatively, suggesting that both techniques were effective for postoperative analgesia after hip arthroplasty. However, it would be suitable to add a control group with sham block to verify the effectiveness of IPB in the future study. Fourth, there was no blinding in this study when performing nerve blocks or analyzing data. This lack of blinding could have introduced bias in the outcome analysis. Lastly, the relatively small sample size may limit the robustness of some secondary outcomes. This size limitation also means we may have overlooked potential adverse effects of IPB, such as infection or in-hospital falls. Future studies with larger sample sizes could address these limitations and provide more reliable results.