Background: Unexplained postoperative pain is one of the most feared complications of total knee arthroplasty (TKA). A persistent noxious peripheral stimulus, such as the pain of chronic knee osteoarthritis, can cause central sensitization in which the central nervous system becomes hyperexcitable, resulting in hypersensitivity to both noxious and non-noxious stimuli. Patients with central sensitization may be more susceptible to unexplained pain after TKA. Duloxetine, a selective serotonin norepinephrine reuptake inhibitor (SNRI), can ameliorate the pain associated with central sensitization, and we aimed to determine whether it could reduce postoperative pain and improve quality of recovery after TKA in patients with central sensitization. Methods: Patients undergoing TKA were screened for central sensitization preoperatively with use of the Central Sensitization Inventory (CSI). Among 464 patients with primary osteoarthritis who were scheduled for primary unilateral TKA, 80 were identified as being centrally sensitized and were included in the study. Forty patients were randomly assigned to the duloxetine group (30 mg 1 day before surgery and for 6 weeks after surgery), and 40 were randomized to the control group (no duloxetine). Pain and quality of recovery were assessed with use of the Brief Pain Inventory (BPI), the Short Form-36 (SF-36), the Measure of Intermittent and Constant Osteoarthritis Pain (ICOAP), and the Hamilton Depression Scale. The prevalence of adverse medication effects was also noted. Results: The patients in the duloxetine group had better performance across pain metrics during the initial 2 to 12-week postoperative period (p < 0.05). The duloxetine group also had a superior quality of recovery 2 weeks after TKA, as indicated by emotional and physical functioning (all p < 0.05). There was no difference between groups in the prevalence of adverse events. Conclusions: A substantial number of patients are centrally sensitized before TKA. Surgeons should consider selective incorporation of duloxetine into the multimodal postoperative analgesic protocol, according to the severity of central sensitization, to minimize the possibility of persistent pain following TKA. Level of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Introduction: Adequate bone quality is essential for long term biologic fixation of cementless total knee arthroplasty (TKA). Recently, vertebral bone quality evaluation using dual-energy computed tomography (DECT) has been introduced. However, the DECT bone mineral density (BMD) in peripheral skeleton has not been correlated with Hounsfield units (HU) or central dual-energy X-ray absorptiometry (DXA), and the accuracy remains unclear. Materials and methods: Medical records of 117 patients who underwent TKA were reviewed. DXA was completed within three months before surgery. DECT was performed with third-generation dual source CT in dual-energy mode. Correlations between DXA, DECT BMD and HU for central and periarticular regions were analyzed. Receiver operating characteristic (ROC) curves were plotted and area under the curve (AUC), optimal threshold, and sensitivity and specificity of each region of interest (ROI) were calculated. Results: Central DXA BMD was correlated with DECT BMD and HU in ROIs both centrally and around the knee (all p < 0.01). The diagnostic accuracy of DECT BMD was higher than that of DECT HU and was also higher when the T-score for second lumbar vertebra (L2), rather than for the femur neck, was used as the reference standard (all AUC values: L2 > femur neck; DECT BMD > DECT HU, respectively). Using the DXA T-score at L2 as the reference standard, the optimal DECT BMD cut-off values for osteoporosis were 89.2 mg/cm³ in the distal femur and 78.3 mg/cm³ in the proximal tibia. Conclusion: Opportunistic volumetric BMD assessment using DECT is accurate and relatively simple, and does not require extra equipment. DECT BMD and HU are useful for osteoporosis screening before cementless TKA.