Knee osteoarthritis (KOA) can be associated with local and central sensitization. As an indicator of the central gain, facilitated temporal summation of pain (TSP) has been found in KOA patients. This facilitation is predictive of the development of chronic postoperative pain after total knee arthroplasty (TKA). Other studies have suggested hypoesthesia/hypoalgesia to thermal stimuli as a feature in KOA. This study investigated associations between preoperative TSP, thermal sensitivity, and radiologic severity for the development of chronic postoperative pain after TKA.
Radiologic KOA (Kellgren and Lawrence), TSP, and thermal stimuli were collected, preoperatively. Clinical knee pain intensity (VAS 0-10) was assessed before and 12 months following TKA. Patients were categorized into a chronic postoperative pain group if they experienced <30% pain reduction of the initial pain after 12 months.
In total, 19% of the patients were categorized as chronic pain patients and presented facilitated preoperative TSP (P<0.05) and a trend towards increased heat pain threshold (P=0.077) compared with patients with normal recovery. Pearson correlations found that preoperative TSP (R=0.193; P=0.013), Kellgren and Lawrence (R=−0.168; P=0.027), warm detection threshold (R=0.195; P=0.012), and heat pain threshold (R=0.196; P=0.012) were associated with pain intensity 12 months after TKA where TSP was identified as an independent factor.
This study showed that preoperatively facilitated TSP in KOA patients was predictive of the development of chronic postoperative pain following TKA. Furthermore, this study is the first to find an association between preoperative hypoalgesia to heat and the development of chronic postoperative pain following TKA.
*SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University
†Aalborg University Hospital, Orthopaedic Surgery Research Unit, Aalborg, Denmark
Supported by the Danish Rheumatism Association, Copenhagen, Denmark, The Innovation Fund Denmark, Copenhagen, Denmark (j.no. 136-2014-5), and The Shionogi Science Program, London, UK are acknowledged for providing the opportunity to conduct the study. The authors declare no conflict of interest.
Reprints: Lars Arendt-Nielsen, PhD, DMSc, SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Fredrik Bajers Vej 7 D3, DK-9220 Aalborg, Denmark (e-mail: LAN@HST.AAU.DK).
Received March 31, 2017
Received in revised form May 8, 2017
Accepted June 11, 2017