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[Purpose] Rotating hinge knee prostheses are often used in primary total knee arthroplasty. However, the biomechanics resulting from this treatment remain unexplored. This cross-sectional study compared patient data on gait kinetics and kinematics to assess the efficacy of primary total knee arthroplasty using a rotating hinge knee or other prostheses. [Participants and Methods] Thirty-three participants were assigned to the following groups: rotating hinge knee (n=7); cruciate-retaining prosthesis (n=7); untreated osteoarthritis (n=10); and young adults as a reference group (n=9). Participant data on biomechanical and spatiotemporal parameters were analyzed. [Results] The postoperative course of the rotating hinge knee group was not significantly longer than that of the cruciate-retaining prosthesis group. The knee varus angle and adduction moment of the rotating hinge knee group were significantly smaller than those of the untreated osteoarthritis group. Gait kinetics and kinematics were not different between the rotating hinge knee and cruciate-retaining prosthesis groups. [Conclusion] Participants who had undergone primary total knee arthroplasty with a rotating hinge knee prosthesis had worse preoperative conditions and demonstrated a similar postoperative gait as those who had undergone total knee arthroplasty with other prostheses. Our findings may be used to tailor rehabilitation programs for participants who have undergone total knee arthroplasty with a rotating hinge knee implant.

Background/Objective: The number of revision total knee arthroplasty (TKA) procedures performed worldwide is increasing. The rotating hinge knee type (RHK) is used for revision TKA. There has been no report on motion analysis of patients with RHK prosthesis. Therefore, this study aimed to clarify the kinetics and kinematics during gait in patients who underwent revision TKA with an RHK prosthesis.Methods: This study had a cross-sectional design. The patients who underwent revision TKA with an RHK prosthesis (R-RHK; 14 patients, 24 knees), those who underwent unilateral primary TKA with a cruciate-retaining (CR) type prosthesis (uniCR; five patients, 5 knees), and those who underwent bilateral primary TKA with a CR type prosthesis (bilCR; 10 patients, 20 knees) were included. Their comfortable gait was analyzed. Spatiotemporal parameters and knee joint angle and moment were calculated. The knee joint angle and tibia translation were compared among the three groups using analysis of variance and a post-hoc Tukey test. The knee adduction moment was compared between groups by analysis of covariance controlling for gait speed.Results: Gait speed of the R-RHK group was significantly less than that of the other groups. The knee joint angle, knee adduction moment, and tibia translation were not different between the R-RHK, uniCR, and bilCR groups during gait and at the beginning of the stance phase.Conclusions: The gait of patients undergoing revision surgery using an RHK prosthesis because of aseptic loosening may have the same biomechanics as that of patients undergoing primary TKA using a different type of prosthesis.

The prevalence of multiple falls is higher in older women, and knee pain is associated with multiple falls in women; thus, it is important to detect individuals at risk of fractures among women with knee osteoarthritis. We aimed to clarify the association between knee osteoarthritis and the quantitative ultrasound (QUS) parameter, and investigate the clinical relevance of the QUS parameter with osteoarthritis-related characteristics in women with knee osteoarthritis. This was a cross-sectional study. We recruited 101 women with knee osteoarthritis at a local orthopedic hospital and 102 healthy individuals from the community. Heel QUS measurements were performed using the QUS device, measuring the stiffness index. We also assessed knee pain, quadriceps strength, and physical activity in women with knee osteoarthritis. We fitted a multiple regression model to estimate the association between knee osteoarthritis and the stiffness index. We also fitted 3 multiple regression models to investigate the clinical relevance of the QUS parameter with osteoarthritis-related characteristics in women with knee osteoarthritis. Compared with the control group, individuals with grade 2 osteoarthritis did not demonstrate a significant difference in stiffness index (p = 0.68); however, those with grade 3 osteoarthritis (p0.001) and 4 (p0.001) showed a lower stiffness index than that of the control group. Additionally, although the QUS parameter did not show an association with knee pain score (p = 0.70) or quadriceps strength (p = 0.11), we found a significant association between the QUS parameter and physical activity (p = 0.003). Our results demonstrate that women with moderate or severe knee osteoarthritis showed lower QUS parameters compared to healthy women, and the QUS parameter was associated with physical activity in women with knee osteoarthritis.

Background: The monitoring of the effects of direct oral anticoagulants may be beneficial during emergencies and adverse events. We aimed to explore direct oral anticoagulant monitoring in “real-world” settings, in which monitoring methods are limited and loading time can be estimated based on only patient reports. Methods: In 164 patients, plasma anti-Xa activity was assessed using a STA ® -Liquid Anti-Xa reagent (Diagnostica Stago, Asnieres, France), and prothrombin time was measured using HemosIL ® RecombiPlasTin 2G (Instrumentation Laboratory, Bedford, MA, USA). The loading time was calculated according to the previous dosing time reported by the patient. In the clinic setting, rivaroxaban and apixaban were administered to 103 patients with atrial fibrillation and a blood sample was tested once during a clinic visit. In the hospitalization setting, edoxaban was administered to 61 patients undergoing arthroplasty for prophylaxis of a venous thrombosis and blood samples were tested 3 and 18 h after the last intake. Results: Plasma Xa activity in the clinical setting ranged widely (rivaroxaban: 1.1–424.4 ng/mL, apixaban: 15.4–469.2 ng/mL) during the 11.7 ± 7.0 h following the previous dose. The values varied over a wide range (up to a factor of 2) at the same loading time, especially around the peak period. The plasma anti-Xa activity of rivaroxaban and apixaban showed linear correlations with prothrombin time (R 2 = 0.828 and 0.717, respectively). Edoxaban administration prolonged the prothrombin time by only 1.6 ± 1.1 s from the trough to the peak, to a degree that was negatively correlated with age, but not with plasma creatinine level, creatinine clearance, or body mass index. Conclusion: In real-world settings, plasma anti-Xa monitoring should be interpreted considering the wide variations in data, reflecting the variability in patient-reported loading time and interpatient variability.