Does living at high altitude increase the risk of bleeding events after total knee arthroplasty? A retrospective cohort study.

OBJECTIVE: Post-operative bleeding after total knee arthroplasty (TKA) is a frequent cause of post-operative complications. This study compared blood loss and indicators of coagulation and fibrinolysis between TKA patients living at low or high altitudes. METHODS: We retrospectively analyzed 120 patients at our institution who underwent primary TKA from May 2019 to March 2020, and we divided them into those living in areas about 500 m or > 3000 m above sea level. We compared the primary outcome of total blood loss between them. We also compared them in terms of several secondary outcomes: coagulation and fibrinolysis parameters, platelet count, reduction in hemoglobin, hidden blood loss, intra-operative blood loss, transfusion rate, and incidence of thromboembolic events and other complications. RESULTS: Total blood loss was significantly higher in the high-altitude group than in the low-altitude group (mean, 748.2 mL [95% CI, 658.5-837.9] vs 556.6 mL [95% CI, 496.0-617.1]; p = 0.001). The high-altitude group also showed significantly longer activated partial thromboplastin time, prothrombin time, and thrombin time before surgery and on post-operative day one, as well as increased levels of fibrinogen/fibrin degradation product on post-operative days one and three. Ecchymosis was significantly more frequent in the high-altitude group (41.7 vs 21.7%; relative risk (RR) = 1.923 [95% CI, 1.091-3.389]; p = 0.019). The two groups showed similar transfusion rates, and none of the patients experienced venous thromboembolism, pulmonary embolism, or infection. CONCLUSION: High altitude may alter coagulation and fibrinolysis parameters in a way that increases risk of blood loss after TKA. Such patients may benefit from special management to avoid bleeding events.

Semi-synthesis, antibacterial activity, and molecular docking study of novel pleuromutilin derivatives bearing cinnamic acids moieties.

To develop new antibiotics owning a special mechanism, we used the molecular assembly method to synthesize a series of novel pleuromutilin derivatives containing a cinnamic acid scaffold at the C-14 side chain. We evaluated their antibacterial activity and used in silico molecular docking to study their binding mode with the target. The structure-activity relationship (SAR) study suggested that compounds with NO2 (13e), OH (13u), and NH2 (13y) appeared more active (0.0625-2 µg/mL) in vitro against several penicillin-resistant Gram-positive bacteria and the position of the substituent on the benzene ring would affect the activity. The in vivo efficacy investigation of 13e, 13u, and 13y with once daily intragastric (i.g.) administration at 40 mg/kg for 3 consecutive days in a mouse systemic infection model showed that 13u had equal activity as valnemulin providing the mice with 60% survival, while 13e and 13y gave 30 and 40% survival, respectively. The molecular docking studies indicated that π-π stacking and hydrogen bond formation played important roles in improving the antibacterial activity.

Core Decompression Prevents Progression of Asymptomatic Type C Osteonecrosis of Femoral Head According to the Japanese Investigation Committee Classification: A Retrospective Study.

OBJECTIVE: To evaluate whether core decompression could prevent progression of asymptomatic type C osteonecrosis of the femoral head (ONFH) according to the Japanese Investigation Committee (JIC) classification. METHODS: This retrospective cohort study included 124 hips (117 patients) with asymptomatic type C ONFH. Seventy-one hips (67 patients) received core decompression (core decompression group) and 53 hips (50 patients) received no surgical treatment (control group). Clinical and radiological follow-up was conducted at 6 and 12 months, then annually until 5 years. Clinical outcomes were evaluated in terms of the Oxford hip score and UCLA Activity Level rating. Radiological outcomes were evaluated using X-ray and magnetic resonance imaging. Survival analysis was performed based on collapse of the femoral head as the first endpoint and total hip arthroplasty (THA) as the second endpoint. RESULTS: There were no significant differences in clinical outcomes between the core decompression group and the control group within 2 years after surgery. Patients in the core decompression group had significantly better Oxford hip score and UCLA Activity Level from year 3 to the end of follow-up (P < 0.05). In year 5, the absolute difference in Oxford hip score (5.3 points) exceeded the reported minimal clinically important difference (MCID, 5.2 points). In years 3-5, the absolute difference in UCLA Activity Level rating (0.95 points, 0.95 points, and 0.99 points, respectively) exceeded the reported MCID (0.92 points). By 5-year follow-up, significantly fewer patients in the core decompression group had experienced femoral head collapse (40.8% vs 62.3%, P = 0.011) or received THA (26.8% vs 45.3%, p = 0.022). CONCLUSIONS: Core decompression can prevent progression of asymptomatic type C ONFH according to the JIC classification, leading to better medium-term hip function and activity levels than no surgical treatment. Core decompression is recommended for early intervention against asymptomatic type C ONFH.

Intravenous Tranexamic Acid for Reducing Perioperative Blood Loss During Revision Surgery for Vancouver Type B Periprosthetic Femoral Fractures After Total Hip Arthroplasty: A Retrospective Study.

OBJECTIVE: To explore the efficacy and safety of intravenous tranexamic acid for reducing perioperative blood loss and allogeneic blood transfusions in revision surgery for Vancouver type B periprosthetic femoral fractures after total hip arthroplasty (THA). METHODS: We retrospectively reviewed 129 patients who underwent revision surgeries because of Vancouver type B periprosthetic femoral fractures from January 2008 to September 2018. Patients were divided into two groups according to whether they received intravenous tranexamic acid (n = 72) or not (n = 57). The two groups were compared in terms of estimated intraoperative blood loss, visible blood loss, hidden blood loss, the volume of allogeneic blood transfusion and the incidence of symptomatic venous thromboembolism (VTE). Patients were also compared depending on the Vancouver classification (Vancouver type B1, B2, and B3). RESULTS: Regardless of the subtype of Vancouver classification, patients who received tranexamic acid showed significantly lower estimated intraoperative blood loss, visible blood loss, hidden blood loss, and allogeneic blood transfusion volume. Use of tranexamic acid was not associated with significant changes in the incidence of postoperative symptomatic VTE. Similar results were obtained with subgroups of patients who had the Vancouver type B1, B2, or B3 periprosthetic femoral fractures. CONCLUSIONS: The administration of intravenous tranexamic acid can safely and effectively reduce perioperative blood loss and allogeneic blood transfusions in revision surgery for Vancouver type B periprosthetic femoral fractures, without increasing the risk of symptomatic VTE.