Less Severe Preoperative Synovitis is Associated with Higher Self-reported Pain Intensity 12 Months After Total Knee Arthroplasty - An Exploratory Prospective Observational Study

• Published in: The Clinical journal of pain
• Main Authors: Petersen, Kristian Kjær, Arendt-Nielsen, Lars, Vela, Jonathan, Skou, Søren T, Eld, Mikkel, Al-Mashkur, Nasir Musa, Boesen, Mikael, Riis, Robert Gabriel Coumine, Simonsen, Ole
• Format: Journal Article
• Language: English
• Published: United States 01.01.2020
• ISSN: 1536-5409
• DOI: 10.1097/AJP.0000000000000768

Synovitis is one of the possible pain generators in osteoarthritis (OA) and associated with upregulation of pro-inflammatory cytokines, which can lead to worsening of the postoperative pain. This explorative study aimed to investigate the association between perioperative synovitis and self-reported pain 12-months after total knee arthroplasty (TKA) in patients with OA. Twenty-six knee OA patients were included in this analysis. Perioperative volume of synovitis in predefined locations was assessed by contrast enhanced magnetic resonance imaging (CE-MRI) and dynamic CE-MRI (DCE-MRI). Perioperative synovitis was assessed histologically from biopsies of the synovium. Highest pain intensity within the last 24-hours (visual analog scale, VAS, 0-100) was assessed before and 12-months after TKA. Patients were divided into a low-pain intensity (VAS≤30) and a high-pain intensity (VAS>30) group based on 12-months postoperative VAS. The high-pain intensity group had significantly lower perioperative CE-synovitis (P=0.025), DCE-synovitis (P<0.04) and a trend towards lower histologically assessed synovitis (P=0.077) compared to the low-pain intensity group. Perioperative synovitis scores were inversely correlated with pain intensity 12-months after TKA (P<0.05), indicating that more severe perioperative synovitis is associated with less severe pain intensity at 12-months. Higher degrees of perioperative synovitis scores are found to be associated with less postoperative pain 12-months after TKA. Further, correlation analysis revealed that less severe perioperative CE-MRI and DCE-MRI synovitis was associated with higher pain intensity 12-months after TKA, suggesting that CE and DCE-MRI synovitis grades could be used as imaging markers for prediction of chronic postoperative pain after TKA.