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

Petersen, Kristian K. MSc, PhD*,†; Arendt-Nielsen, Lars MSc, PhD*; Vela, Jonathan MD‡,§; Skou, Søren T. MSc, PhD∥,¶; Eld, Mikkel MD‡,#; Al-Mashkur, Nasir M. MD‡,#; Boesen, Mikael MD, PhD**; Riis, Robert G.C. MD, PhD**,††; Simonsen, Ole MD, PhD‡,‡‡

doi: 10.1097/AJP.0000000000000768
Original Articles

Objectives: Synovitis is one of the possible pain generators in osteoarthritis (OA) and is associated with upregulation of proinflammatory cytokines, which can lead to worsening of the postoperative pain. This exploratory study aimed to investigate the association between perioperative synovitis and self-reported pain 12 months after total knee arthroplasty (TKA) in patients with OA.

Materials and Methods: Twenty-six knee OA patients were included in this analysis. The perioperative volume of synovitis in predefined locations was assessed by contrast-enhanced magnetic resonance imaging (CE-MRI) and dynamic contrast-enhanced magnetic resonance imaging (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 to 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 on the basis of 12 months postoperative VAS.

Results: The high-pain intensity group had significantly lower perioperative contrast-enhanced-synovitis (P=0.025), DCE-synovitis (P<0.04), and a trend toward lower histologically assessed synovitis (P=0.077) compared with 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.

Discussion: 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-MRI and DCE-MRI synovitis grades could be used as imaging markers for prediction of chronic postoperative pain after TKA.

*Department of Health Science and Technology, Center for Sensory Motor Interaction (SMI)

Department of Health Science and Technology, Center for Neuroplasticity and Pain, Faculty of Medicine

Department of Clinical Medicine, Aalborg University

Departments of §Rheumatology


‡‡Orthopedic Surgery, Aalborg University Hospital, Aalborg

Research Unit for Musculoskeletal Function and Physiotherapy, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense

Department of Physiotherapy and Occupational Therapy, Næstved-Slagelse-Ringsted Hospitals, Region Zealand

**Department of Radiology

††The Parker Institute, Bispebjerg and Frederiksberg Hospital Copenhagen University, Copenhagen, Denmark

Center for Neuroplasticity and Pain (CNAP) is supported by the Danish National Research Foundation, Copenhagen, Denmark, (DNRF121). The authors declare no conflict of interest.

Reprints: Kristian K. Petersen, MSc, PhD, Department of Health Science and Technology, Center for Neuroplasticity and Pain (CNAP), Center for Sensory Motor Interaction (SMI), Faculty of Medicine, Aalborg University, Fredrik Bajers Vej 7 D3, Aalborg DK-9220, Denmark (e-mail:

Received March 12, 2019

Received in revised form August 8, 2019

Accepted September 8, 2019

Online date: September 17, 2019

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