The Combination of Preoperative Pain, Conditioned Pain Modulation, and Pain Catastrophizing Predicts Postoperative Pain 12 Months After Total Knee Arthroplasty

Objectives. Approximately 20% of knee osteoarthritis patients undergoing total knee arthroplasty (TKA) report chronic postoperative pain. Studies suggest that preoperative variables such as impaired descending pain control, catastrophizing, function, and neuropathic pain-like symptoms may predict postoperative pain 12 months after TKA, but the combined prediction value of these factors has not been tested. The current prospective cohort study aimed to combine preoperative risk factors to investigate the predictive value for postoperative pain 12 months after TKA. Design. Prospective cohort with follow-up 12 months after surgery. Patients. A consecutive sample of 131 knee osteoarthritis patients undergoing TKA. Methods. Pain intensity, Pain Catastrophizing Scale (PCS) scores, PainDETECT Questionnaire scores, conditioned pain modulation (CPM), and Oxford Knee Score (OKS) were obtained before and 12 months after TKA. Results. TKA improved pain (P < 0.001), PCS scores (P < 0.001), PainDETECT Questionnaire scores (P < 0.001), and OKSs (P < 0.001). Preoperative pain correlated with preoperative PCS scores (r = 0.38, P < 0.001), PainDETECT scores (r = 0.53, P < 0.001), and OKSs (r = -0.25, P = 0.001). Preoperative PainDETECT scores were associated with preoperative PCS scores (r = 0.53, P < 0.001) and OKSs (r = -0.25, P = 0.002). Higher postoperative pain was correlated with high preoperative pain (r = 0.424, P < 0.001), PCS scores (r = 0.33, P < 0.001), PainDETECT scores (r = 0.298, P = 0.001), and lower CPM (r = -0.18, P = 0.04). The combination of preoperative pain, PCS score, and CPM explained 20.5% of variance in follow-up pain. PCS scores had a significant effect on pain trajectory when accounting for patient variance (t = 14.41, P < 0.0005). Conclusion. The combination of high preoperative clinical pain intensity, high levels of pain catastrophizing thoughts, and impaired CPM may predict long-term postoperative pain 12 months after surgery.