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.

Background: Posterior-stabilized and ultracongruent designs are 2 common examples of posterior cruciate ligament-substituting total knee arthroplasty (TKA) prostheses. There is a lack of evidence regarding joint perception differences between ultracongruent and posterior-stabilized TKA. The purpose of this study was to compare the postoperative knee stability, function, and joint perception between ultracongruent and posterior-stabilized TKA in the same patients in order to determine whether there was a difference based on design. Methods: This prospective, randomized controlled trial included 50 patients who underwent same-day bilateral TKA utilizing Persona (Zimmer Biomet) posterior-stabilized implants in 1 knee (posterior-stabilized group) and ultracongruent implants in the other knee (ultracongruent group). At 2 years postoperatively, patients were evaluated for knee stability, function, and joint perception. Postoperative static knee anteroposterior stability and femoral rollback were compared. Knee function was evaluated with use of the Knee Society Score and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Joint perception was compared by evaluating noise generation, side preference, satisfaction, and the Forgotten Joint Score. Results: The ultracongruent group had more knee anteroposterior laxity (4.5 mm compared with 1.8 mm in the posterior-stabilized group; p < 0.001) and less femoral rollback (4.2 mm compared with 9.0 mm in the posterior-stabilized group; p < 0.001). Knee Society Score and WOMAC scores were not significantly different between groups (all p > 0.05). Although the ultracongruent group showed less noise generation than the posterior-stabilized group (18% compared with 38%, respectively; p = 0.026), there were no differences in side preference, satisfaction, or Forgotten Joint Score (all p > 0.05). Conclusions: Both groups had similar joint perception 2 years postoperatively, with obvious differences in noise generation and more sagittal laxity with less femoral rollback in the ultracongruent group. Level of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Background: To our knowledge, it is still unknown if central sensitization (CS) influences the magnitude of the minimal clinically important difference (MCID) for patient-reported outcome measures after total knee arthroplasty (TKA). The purpose of this study was to determine the influence of CS on the MCID for the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score in patients who underwent TKA for knee osteoarthritis. Methods: A total of 422 patients who underwent unilateral TKA and completed a 2-year follow-up were enrolled in this study. CS was measured using the Central Sensitization Inventory (CSI). The WOMAC score was used to evaluate preoperative and postoperative patient-reported outcomes. The measurement of the MCID was performed separately for patients with and without CS using both the anchor-based method and the distribution method. The change difference method defined the MCID as the difference in preoperative-to-postoperative change between the minimal-improvement group and the no-change group. In addition, the MCID was calculated using receiver operating characteristic (ROC) curve analysis. The percentage of MCID achievement in each group was also compared. Results: According to the change difference method, the MCID for the WOMAC total score was 23.4 points for patients with CS and 14.7 points for patients without CS. The MCID using the ROC cutoff value for the WOMAC total score was 29.5 points for the patients with CS and 26.5 points for the patients without CS. MCID achievement rates in WOMAC pain, function, and total scores were all found to be significantly higher in the patients without CS through the change difference method and the ROC method (all p < 0.05). Conclusions: The MCID for the WOMAC score of patients with CS after TKA was greater than that for patients without CS. Furthermore, by applying the calculated MCID to the group to which the patients belonged (with or without CS), we determined that patients with CS showed a lower MCID achievement rate than patients without CS. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

(1) Background: The purpose of this study was to evaluate the efficacy and safety of intravenous (IV) ferric carboxymaltose (FCM) to treat acute postoperative anemia following same-day bilateral total knee arthroplasty (TKA). (2) Methods: A total of 118 patients who underwent same-day bilateral TKA were randomly assigned to two groups: an FCM group (FCM infusion, 58 patients) and a Control group (placebo with normal saline, 60 patients). The primary endpoint was the number of responders with a Hb increase of two or more points by the second postoperative week. The secondary endpoints were Hb level, iron metabolism variables and blood transfusion rate at 2, 6 and 12 weeks after surgery. (3) Results: The FCM group had more Hb responders than the Control group (62.1% vs. 31.6%, p < 0.001). The Hb level was significantly higher in the FCM group during 12 weeks after surgery (all p < 0.05). Ferritin, iron and transferrin saturation levels were significantly higher in the FCM group from 2 to 12 weeks postoperatively (all p < 0.05). There was no difference in transfusion rate after surgery (p > 0.05). (4) Conclusion: In patients with postoperative anemia after same-day bilateral TKA, IV FCM infusion significantly improved Hb response two weeks after surgery without severe adverse events compared to placebo. In contrast, transfusion rate and various parameters of quality of life assessment up to 12 weeks did not vary between these groups. Level of evidence: Level I.

Background: Ferric carboxymaltose (FCM) is an intravenous (IV) high-dose iron that is effective in the treatment of iron deficiency anemia. This study was performed to determine whether postoperative FCM infusion is effective at improving hemoglobin (Hb) responders, Hb and iron profiles, and the patient’s quality of life (QOL). Methods: A total of 110 patients with postoperative anemia, defined by a Hb < 10 g/dL within 3 days of unilateral primary TKA, between June 2018 and February 2020 were randomized into either the FCM or Control group. On postoperative day 3, the FCM group (55 patients) received IV FCM while the Control group (55 patients) did not. The Hb responders (Hb increase ≥ 2 g/dL compared to baseline), Hb level, iron profiles (ferritin, total iron-binding capacity (TIBC), transferrin saturation (TSAT)), and EQ-5D scores were compared at weeks 2, 4, and 8. Results: The FCM group demonstrated a significantly greater number of Hb responders (p < 0.001) and a higher Hb level (p = 0.008) at 2 weeks postoperative than did the Control group. The FCM group recovered its preoperative Hb level between 4 and 8 weeks. In contrast, the Control group did not recover its preoperative level until 8 weeks. The FCM infusion group also had higher serum ferritin, iron and TSAT, and lower TIBC levels than those of the Control group between 2 and 8 weeks (all p < 0.001). However, there was no significant difference in the postoperative transfusion rate (p = 0.741) or EQ-5D score between the two groups (all p > 0.05). Discussion: In postoperative anemia following TKA, IV FCM increases the Hb response and improves Hb and iron metabolism variables, however, it does not affect the transfusion rate or QOL.