Improving analgesia research after total knee arthroplasty: Objective metrics,opioid monitoring,and operator factors

Dear Editor,

Casimiro et al (2025) offered valuable contributions to the understanding of how analgesic technique influences short-term patient-reported outcomes following total knee arthroplasty (TKA). Their findings underscore the clinical relevance of comparing epidural analgesia and peripheral nerve blocks in the immediate postoperative period. However, several methodological and analytical aspects warrant further discussion to enhance the interpretation of their results and to help inform future research in perioperative pain management and functional recovery.

First, current evaluations of postoperative analgesic effectiveness rely predominantly on patient-reported outcomes, such as pain perception and improvements in quality of life. While these measures provide important insights into the patient’s subjective experience, they are also susceptible to influence from emotional state, personal expectations, and cultural background, which may compromise objectivity. To better capture the true clinical impact of analgesic strategies on postoperative recovery, future research should incorporate objective functional indicators. Measures such as total walking distance during early recovery, time to first mobilisation, range of motion in the operated knee joint, and the ability to ambulate independently offer more direct and quantifiable evidence of functional restoration (Joshi & Kehlet 2020). These indicators not only enhance the accuracy of recovery assessment but also support more informed and individualised rehabilitation planning. Integrating both subjective and objective domains within a unified assessment framework will be essential for advancing the methodological quality and clinical applicability of future analgesia research.

Second, pain intensity scores and the quantification of analgesic consumption, particularly total opioid dosage, are essential objective indicators for evaluating the effectiveness of postoperative analgesic strategies. Although this study assessed early recovery using patient-reported outcome measures, it did not include standardised pain assessments such as the Visual Analogue Scale (VAS) or the Numeric Rating Scale (NRS), nor did it report postoperative opioid or non-opioid consumption within the first 48 h. The absence of these data limits the ability to accurately interpret the true analgesic effectiveness of the techniques being compared. Considering the individual variability in pain perception and the strong association between opioid use and postoperative complications, such as nausea, constipation, and sedation, future studies should systematically collect both pain scores and analgesic usage. In particular, opioid dosage is a key parameter for assessing the opioid-sparing effect, which is fundamental when comparing analgesic modalities like epidural analgesia and peripheral nerve blocks (Abdel et al 2016, Paul et al 2021). Including these objective endpoints would enhance the clinical relevance and comprehensiveness of pain management evaluations.

Third, operator proficiency and clinical experience play a critical role in the effectiveness of regional anaesthesia techniques. For both peripheral nerve blocks and epidural analgesia, outcomes such as block success rate, duration of analgesia, and complication control can be significantly influenced by the clinician’s technical skill. Variability in experience levels across providers may introduce performance bias and affect the comparability of outcomes between study groups. Moreover, regional anaesthesia procedures are known to involve a learning curve, with differences in technique execution, drug administration, and complication management between novice and experienced practitioners (Weil et al 2017). Future studies of this kind would benefit from standardised procedural protocols and, where feasible, consideration of operator experience as a covariate in statistical analyses. These measures could enhance internal validity and improve the clinical applicability of study findings.

In conclusion, we sincerely appreciate the authors’ valuable contribution to advancing the understanding of analgesic strategies following TKA. We hope that our reflections offer constructive perspectives to further enrich future research in perioperative pain management and functional recovery. Addressing these additional considerations may contribute to more comprehensive, evidence-based, and patient-centred approaches in the field of postoperative rehabilitation.