Predictors of persistent pain after total knee arthroplasty

Abstract

Editor—I read with great interest the review article by Lewis and colleagues,1Lewis GN Rice DA McNair PJ Kluger M Predictors of persistent pain after total knee arthroplasty: a systematic review and meta-analysis.Br J Anaesth. 2015; 114: 551-561Abstract Full Text Full Text PDF PubMed Scopus (307) Google Scholar who presented in an extremely lucid yet detailed fashion the predictors of persistent pain after total knee arthroplasty (TKA). An indwelling epidural catheter remains the most popular mode of postoperative analgesia in patients who undergo TKA. But many centres are now managing postoperative pain with a continuous femoral nerve catheter or adductor canal block. Periarticular local anaesthetic infiltration is also used in several centres. These are very efficient ways of managing postoperative pain and help in early mobilization. But the type of postoperative analgesia does not in any way help in reducing persistent or chronic pain in these patients. Buvanendran and colleagues2Buvanendran A Kroin JS Della Valle CJ Kari M Moric M Tuman KJ Perioperative oral pregabalin reduces chronic pain after total knee arthroplasty: a prospective, randomized, controlled trial.Anesth Analg. 2010; 110: 199-207Crossref PubMed Scopus (342) Google Scholar studied the efficacy of pregabalin, starting before TKA and continuing for 14 days after surgery, in reducing the severity of persistent pain. They reviewed the patients at the end of 30 days, 3 and 6 months and found that the incidence of neuropathic pain was less compared with placebo. However, sedation and confusion were greater in these patients. In my opinion, the dose of pregabalin used was high or was not titrated to requirement. Likewise, gabapentin is used as an adjunct to postoperative pain management after major surgeries but it has not been found to help in alleviating persistent pain after TKA. Lewis and colleagues1Lewis GN Rice DA McNair PJ Kluger M Predictors of persistent pain after total knee arthroplasty: a systematic review and meta-analysis.Br J Anaesth. 2015; 114: 551-561Abstract Full Text Full Text PDF PubMed Scopus (307) Google Scholar could have described the studies in which some sort of chronic pain-modulating agent (pregabalin, gabapentin, or antidepressant) was used by patients in the perioperative period and described the nature of chronic pain in these patients attributable to usage of these agents. The review has also highlighted the fact that severe, catastrophic preoperative pain has the greatest effect on the severity of postoperative pain, which leads to persistent pain in the subsequent weeks. Looking at the available evidence on the use and efficacy of pain-modulating drugs in reduction of opioid consumption and the relatively less persistent pain compared with placebo, I think it is not a bad idea to start TKA patients on these drugs when they consult the anaesthetist for the pre-anaesthesia check-up. Patients should be instructed to inform the health-care team if they experience drowsiness or confusion so that dose adjustment can be made or an alternative drug can be started. The same drug can also be continued after surgery. However, there is no description in the available literature of the optimal duration of these agents after surgery. None declared.