Patients with knee osteoarthritis demonstrate decreased pressure pain thresholds (PPTs), facilitated temporal summation (TS) of pain, and decreased conditioned pain modulation (CPM) compared with healthy controls. This study aimed to correlate preoperative PPTs, TS, and CPM with the development of chronic postoperative pain after total knee replacement (TKR) surgery. Knee pain intensity (visual analog scale [VAS]: 0-10), PPTs, TS, and CPM were collected before, 2 months, and 12 months after TKR. Patients were divided into a low-pain (VAS < 3) and a high-pain (VAS ≥ 3) group based on their VAS 12 months after TKR. The high-pain group (N = 17) had higher pain intensities compared with the low-pain group (N = 61) before surgery (P = 0.009) and 12 months after surgery (P < 0.001). The PPTs of the low-pain groups were normalized for all measurement sites comparing presurgery with 12 months postsurgery (P < 0.05, contralateral arm: P = 0.059), which was not the case for the high-pain group. The low-pain group showed a functional inhibitory CPM preoperatively and 12 months postoperatively (P < 0.05), which was not found in the high-pain group. The high-pain group had higher facilitated TS preoperatively and 12 months postoperatively compared with the low-pain group (P < 0.05). Preoperative TS level correlated to 12-month postoperative VAS (R = 0.240, P = 0.037). Patients who developed moderate-to-severe pain had pronociceptive changes compared with patients who developed mild pain postsurgery. Preoperative TS level correlated with the postoperative pain intensity and may be a preoperative mechanistic predictor for the development of chronic postoperative pain in patients with osteoarthritis after TKR.
Temporal summation may be a mechanistic preoperative predictor of the development of chronic postoperative pain in patients with knee osteoarthritis after total knee replacement surgery.
aCenter for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark
bOrthopaedic Surgery Research Unit, Aalborg University Hospital, Aalborg, Denmark
cDepartment of Anaesthesiology, Pain and Palliative Medicine, Radboud University Medical Centre, Nijmegen, the Netherlands
Corresponding author. Address: Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Fredrik Bajers Vej 7, D3, DK-9220 Aalborg, Denmark. Tel.: +45 9940 8831; fax: +45 9815 4008. E-mail address: email@example.com (L. Arendt-Nielsen).
Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.
Received August 15, 2014
Received in revised form September 18, 2014
Accepted October 30, 2014