Response to Wang et al. “Comparative analysis of continuous pericapsular nerve group block and supra-inguinal fascia iliaca compartment block for postoperative analgesia in total hip arthroplasty: a randomized controlled trial”

Abstract

We appreciate the opportunity to respond to the thoughtful comments regarding our randomized controlled trial that compared the continuous pericapsular nerve group block and the continuous supra-inguinal fascia iliaca compartment block techniques for postoperative pain management following total hip arthroplasty. Both groups in our study were demographically comparable. All participants underwent elective, unilateral, primary total hip arthroplasty and were classified as American Society of Anesthesiologists physical status I or II. Randomization was performed using a computer-generated sequence with allocation concealment, minimizing the risk of selection bias. In terms of analgesic protocol, every patient received scheduled intravenous administration of the non-steroidal anti-inflammatory drug ibuprofen and patient-controlled analgesia with tramadol. Intravenous paracetamol was administered only as a rescue medication when the visual analog scale pain score exceeded four. Although several guidelines, such as the enhanced recovery after surgery and the procedure-specific postoperative pain management guidelines published by the European Society of Regional Anaesthesia, recommend routine scheduled use of paracetamol along with nonsteroidal anti-inflammatory drugs, both groups in our study followed the same analgesic regimen. This uniformity supports the internal validity of our comparative results. We observed that the group receiving the pericapsular nerve group block showed a continuous decline in pain scores, while the fascia iliaca compartment block group experienced increasing pain after six hours. Although the difference in opioid use was slightly below the minimal clinically important difference, it was accompanied by lower pain scores and less need for rescue medication. We acknowledge the absence of patient-reported outcomes as a limitation and encourage their inclusion in future research.

To the Editor,

We sincerely thank Wang et al. for their interest in our study and for their thoughtful comments regarding our randomized controlled trial comparing continuous pericapsular nerve group (PENG) block and supra-inguinal fascia iliaca compartment block (SIFICB) techniques for postoperative analgesia after total hip arthroplasty (THA) [1]. We appreciate the opportunity to address the points raised.

Regarding baseline comparability, all patients underwent elective, unilateral, primary THA with American Society of Anesthesiologists (ASA) I–II status and were randomly assigned using a computer-generated list. As shown in Table 1 [1], age, sex, body mass index (BMI), ASA scores, and surgery duration were similar between groups. Although variables like preoperative pain or psychological status were not individually recorded, the homogeneity and randomization likely minimized any imbalance. Future studies may benefit from including these parameters.

We acknowledge the comment about paracetamol use. All patients received scheduled intravenous ibuprofen and patient-controlled analgesia (PCA) tramadol; intravenous paracetamol was reserved for breakthrough pain (Visual Analog Scale (VAS) > 4). Enhanced Recovery After Surgery (ERAS) guidelines recommend routine use of both paracetamol and non-steroidal anti-inflammatory drugs (NSAIDs) [2], while Society of Regional Anaesthesia (ESRA)/Procedure-Specific Postoperative Pain Management (PROSPECT) emphasizes their combination as basic analgesia, though it notes limited additive benefit when NSAIDs are already administered [3]. Our approach reflected institutional practice and maintained consistency across groups. Both groups received the same multimodal regimen, preserving internal validity. Notably, the PENG group showed lower opioid use and fewer rescue doses, supporting the clinical relevance of our findings.

The PENG group exhibited sustained pain reduction over 24 h, unlike the SIFICB group, which showed increased pain after 6 h. This is likely due to more consistent blockade of the anterior capsule’s innervation by PENG, especially the accessory obturator and femoral articular branches. In contrast, SIFICB may offer variable coverage. Both techniques used the same local anesthetic regimen, and catheter function was maintained throughout. Future imaging studies may help correlate these anatomical factors with clinical outcomes.

Although the opioid consumption difference (7.3 mg morphine milligram equivalents (MME)) was slightly below the typical minimum clinically important difference (MCID) of 9 mg [4], it is still meaningful in the context of major orthopedic surgery. Even small opioid reductions can decrease adverse effects and improve recovery. Lower VAS scores and reduced rescue needs in the PENG group further support the clinical impact.

We agree that inclusion of patient satisfaction and moderate-to-severe pain incidence would enhance the comprehensiveness of our findings. Our endpoints focused on objective measures, which consistently favored PENG. Future studies should include broader patient-reported outcomes and functional assessments.

In conclusion, we reaffirm the rigor and clinical relevance of our findings. We thank the authors for their engagement and for fostering continued dialogue on improving pain management strategies in THA.

Abbreviations

ASA

American Society of Anesthesiologists

ERAS

Enhanced Recovery After Surgery

ESRA

European Society of Regional Anaesthesia

MME

Morphine Milligram Equivalents

PCA

Patient-Controlled Analgesia

PENG

Pericapsular Nerve Group

SIFICB

Supra-Inguinal Fascia Iliaca Compartment Block

VAS

Visual Analog Scale

Author contributions

OB conceptualized and designed the study, and drafted the initial manuscript. AS critically revised the manuscript for important intellectual content. CA supervised the project. All authors read and approved the final version of the manuscript and agree to be accountable for all aspects of the work.

Funding

The authors report no involvement in the research by the sponsor that could have influenced the outcome of this work.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

No potential conflict of interest relevant to this article was reported. The authors certify that there is no conflict of interest with any financial organization regarding the material discussed in the manuscript.

Clinical trial registration number

Not applicable.

IRB number

Not applicable.