Chronic postoperative pain after total knee arthroplasty: The potential contributions of synovitis, pain sensitization and pain catastrophizing-An explorative study

Abstract

Background: A subset of osteoarthritis patients will experience chronic postoperative pain after total knee arthroplasty (TKA), but the source of pain is unclear. The aim of this exploratory study was to assess patients with and without postoperative pain after TKA using magnetic resonance imaging (MRI), quantitative sensory testing (QST), clinical assessment of pain and assessments of catastrophizing thoughts. Method(s): Forty-six patients completed the 6-month postoperative assessment. MRI findings were scored according to the MRI Osteoarthritis Knee Score recommendation for Hoffa synovitis, effusion size and bone marrow lesions. QST included assessment of pressure pain thresholds (PPTs), temporal summation of pain (TSP) and conditioned pain modulation (CPM). Pain catastrophizing was assessed using the Pain Catastrophizing Scale (PCS). Clinical pain assessment was conducted using a visual analogue scale (VAS, 0-10 cm), and groups of moderate-to-severe (VAS > 3) and none-to-mild postoperative pain (VAS Method(s): Forty-six patients completed the 6-month postoperative assessment. MRI findings were scored according to the MRI Osteoarthritis Knee Score recommendation for Hoffa synovitis, effusion size and bone marrow lesions. QST included assessment of pressure pain thresholds (PPTs), temporal summation of pain (TSP) and conditioned pain modulation (CPM). Pain catastrophizing was assessed using the Pain Catastrophizing Scale (PCS). Clinical pain assessment was conducted using a visual analogue scale (VAS, 0-10 cm), and groups of moderate-to-severe (VAS > 3) and none-to-mild postoperative pain (VAS Result(s): Patients with moderate-to-severe postoperative pain (N = 15) demonstrated higher grades of Hoffa synovitis (p Result(s): Patients with moderate-to-severe postoperative pain (N = 15) demonstrated higher grades of Hoffa synovitis (p Result(s): Patients with moderate-to-severe postoperative pain (N = 15) demonstrated higher grades of Hoffa synovitis (p Result(s): Patients with moderate-to-severe postoperative pain (N = 15) demonstrated higher grades of Hoffa synovitis (p Conclusion(s): These exploratory findings could indicate that chronic postoperative pain after TKA is a combination of joint-related synovitis and effusion, sensitization of central pain mechanisms and potentially pain catastrophizing thoughts, but larger studies are needed to confirm this. Significance: The end-stage treatment of knee osteoarthritis is total knee arthroplasty. Some patients experience chronic postoperative pain after total knee arthroplasty, but the mechanism for chronic postoperative pain is widely unknown. The current study indicates that higher levels postoperative of synovitis and effusion, higher temporal summation of pain and higher pain catastrophizing scores could be associated with higher chronic postoperative pain.Copyright © 2022 The Authors. European Journal of Pain published by John Wiley & Sons Ltd on behalf of European Pain Federation - EFIC .