Reply to

Abstract

Editor, We thank Drs Sondekoppam and Ganapathy for their interest in our trial and their careful reading thereof.1 As described in our article,2 we were also surprised about the results revealing very low postoperative pain scores during the first 24 h after surgery. We considered a 50% reduction in pain scores in the intervention group to be clinically relevant. This threshold was decided before estimating the sample size and was based on our clinical experience, previous studies and an assumption of a much higher pain score than the one observed. On the basis of our results, we cannot conclude that there is no effect of the adductor canal blockade; we just have to accept that the patients in this trial receiving a basic analgesic recipe of paracetamol and ibuprofen in both groups did not have sufficient pain to detect an effect of the blockade. We are aware of the problem about the success rate of the block not being tested. In order to avoid un-blinding of the study, no test of sensibility of the lower extremity (the normal procedure before discharge of patients) was made. We decided to let the risk of introducing a potential confounding factor prevail the wish for knowing the success rate of the performed blocks. We do recommend testing the effect of the adductor canal blockade in routine care. As we interpret our data, the major challenge in this trial was the fact that all patients responded with unexpectedly low pain scores. We expected this specific surgical intervention to cause pain at the hamstring donor site, as well as intraarticular/periarticular pain. We asked the patients to evaluate their ‘overall’ pain level (pain related to the surgical procedure); it would be of no benefit to relieve, for example, their intraarticular pain only if the patients were still in pain due to surgical trauma at the hamstring site. However, ketobemidone consumption in both groups of patients was modest (7.5 vs. 5.0 mg in the control vs. the ropivacaine group, respectively) during the first 24 h after surgery indicating low pain levels in general. Our clinical experience regarding postoperative pain after anterior cruciate ligament reconstruction prior to this trial was based on data from different surgeons, and data from the literature. One surgeon performed the vast majority of the surgical procedures in our trial. We therefore must assume that the surgical intervention performed in the two groups of patients was comparable. But we also have to consider whether the surgical technique could have an impact on the degree of postoperative pain. Maybe it is of importance where and how the tendon from the sartorius or gracilis muscle is being harvested; for example whether or not the periosteum is affected when harvesting the donor tendon. Evaluating the outcome of this trial makes us consider this as a possible important factor for the observed results. Acknowledgements relating to this article Assistance with the letter: none. Financial support and sponsorship: none. Conflicts of interest: none. Presentation: none.