In Response

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We thank Dr Vaughan for his insightful comments that are based on his extensive expertise in providing postoperative analgesia for joint arthroplasty in his letter to the editor, “Analgesia for Total Knee Arthroplasty (TKA): What Is the Best Option?”1 We realize that every study can be critiqued, and that the impact of a clinical trial depends on asking the right questions, employing a methodologically sound approach in answering them, and accounting for various forms of bias and confounding variables.
In the case of our trial,2 Vaughan commented on the use of morphine and ketorolac in the periarticular infiltration (PI) solution and considered this to be a source of bias. We wish to point out that the standard of care in our institution, and in many centers worldwide, is to use a PI solution that includes local anesthetics, nonsteroidal anti-inflammatory drugs, morphine, and epinephrine. Our research question of interest is to compare one care standard and analgesic modality (PI) with another: the adductor canal block (ACB). We have no clinical or research interest in comparing the analgesic effects of the periarticular versus perineural routes of local anesthetics administration. By taking “standardization” to extremes, we risk isolating the interventions being examined from their clinical context.
Vaughan also pointed out that our research2 did not account for posterior knee pain arising in the sciatic nerve distribution. Although we do agree that sciatic block adds clinically meaningful analgesia in the setting of knee arthroplasty, we realize that sciatic block has fallen out of favor in contemporary practice that emphasizes early ambulation and physiotherapy. Practically, we expect posterior knee pain to have similarly influenced the 3 arms of our study, thus minimizing any potential bias or confounding. After all, both PI3 and ACB4–6 may have a role in treating posterior knee pain, as suggested in recent studies. Local infiltration should spread to the posterior capsule, blocking the terminal branches of the sciatic nerve.3 In addition, the ACB has been consistently shown to spread to the popliteal fossa.4–6.
We do agree with Vaughan’s statement that the analgesic option that optimizes pain control and minimizes motor weakness for patients undergoing lower extremity joint arthroplasty continues to be a subject that requires ongoing investigation.
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