Influence of Centrally Mediated Symptoms on Postoperative Pain in Osteoarthritis Patients Undergoing Total Knee Arthroplasty: A Prospective Observational Evaluation.

Background: Central sensitization plays an important role in the chronic pain experienced by osteoarthritis (OA) patients. In this prospective observational study, we investigated the influence of the level of preoperative centrally mediated symptoms measured by the Central Sensitization Inventory (CSI) on pain intensity after total knee arthroplasty (TKA) for OA.

Methods: Ninety-eight female OA patients undergoing TKA were enrolled in this study. We assessed CSI scores, pain-related data, and other clinical data preoperatively. All patients received spinal anesthesia and postoperative epidural analgesia. Pain intensity (at rest and on movement) and rescue meperidine requirements were assessed during postoperative days 1 and 2. Also, pain intensity and patient satisfaction were assessed 1 month and 3 months after surgery. After the completion of all postoperative assessments, we separated the study population into a preoperative CSI score ≥40 and <40 group. We assessed pain-related data between the 2 groups at each assessment time.

Results: Ninety-one patients completed the postoperative assessments (a preoperative CSI ≥40 group; n = 44, CSI <40 group; n = 47). Patients with preoperative CSI ≥40 complained of a greater pain intensity (P = 0.001) during postoperative days 1 and 2 and required a higher dose of meperidine rescue (P = 0.003) than those with a preoperative CSI <40. The high CSI score group also showed a less favorable outcome in terms of pain relief on follow-up at 1 month (P = 0.006) and 3 months (P = 0.002) after surgery. In multivariate analysis, a preoperative CSI score ≥40 was the strongest determinant with 5.091 of the highest odds ratio (95% CI 1.324 to 19.523, P = 0.016) for predicting a persistent pain 3 months after surgery among demographic and pain-related variables.

Conclusions: OA patients with high levels of comorbid centrally mediated symptoms showed severe pain and increased analgesic requirements after TKA in the early postoperative period. Moreover, these patients seemed to be at higher risk of persistent pain, and a high CSI score was predictive of low patient satisfaction in terms of pain relief after surgery.