To the Editor,
We read the study by Hirasawa and colleagues [1] with great interest and would like to make the following points relating to the design of their randomized control trial.
In their study, 45 patients underwent same-day bilateral total hip replacements. This is not a typical cohort of patients; rather, this is a young, fit group of patients who are likely to have fewer comorbidities—a factor that may affect their pain perception and recovery postoperatively. In addition, the underlying diagnosis in this series differs widely from most reports on THAs from outside Asia, in that this series [1] consisted predominantly of patients with developmental dysplasia of the hip.
The primary study outcome was pain measured on a visual analogue scale. We appreciate the authors’ attempts to use participants as their own control parallel group, but undergoing bilateral simultaneous hip replacements would have made it difficult for patients to determine with great accuracy the pain on left and right sides, independent to the contralateral side, which would act as a “distracting injury.”
The authors did not control for the difference in time between surgery completion and patient pain would be dependent on which side was operated on first. For the early assessment time points, there would be a substantial difference between the time of assessment and surgery completion, respective to whether the assessed side was operated on first or second.
The cocktail of infiltration is now out-of-date and enhanced recovery programs are moving towards the use of local anaesthetic infiltration alone with no other drugs [2], and so the study perhaps seems out of touch with current practice. Additionally, no control was made for the size of the patient and the relative dosage of periarticularanalgesia. The variation in weight of the study participants (48.8-70.0Kg) would have had an impact on the relative doses of the analgesics used.
The patients only had nonsteroidals as additional analgesia postoperatively. If the patient was unable to tolerate NSAIDs or had contraindications to their administration but had no other analgesia, then the pain scores are going to be affected. Additionally, all these patients had general anaesthesia, there is no mention of any intraoperative analgesia that was administered. This would presumably have been given and would have varied from patient to patients and affected their pain score in the postoperative period.
Footnotes
(RE: Hirasawa N, Kurosaka K, Nishino M, Nakayama T, Matsubara M, Tsukada S.No clinically important difference in pain scores after THA between periarticular analgesic injection and placebo. Clin Orthop Relat Res. 2018;476:1837-1845.
The authors certify that neither they, nor any members of their immediate families, have any commercial associations (such as consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article.
All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.
The opinions expressed are those of the writers, and do not reflect the opinion or policy of CORR® or The Association of Bone and Joint Surgeons®.
References
- 1.Hirasawa N, Kurosaka K, Nishino M, Nakayama T, Matsubara M, Tsukada S. No clinically important difference in pain scores after THA between periarticular analgesic injection and placebo. Clin Orthop Relat Res. 2018;476:1837-1845. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.McDonald DA, Siegmeth R, Deakin AH, Kinninmonth AWG, Scott NB. An enhanced recovery programme for primary total knee arthroplasty in the United Kingdom — follow up at one year. Knee . 2012;19:525–529. [DOI] [PubMed] [Google Scholar]