Elution and Biomechanical Properties of Meropenem-Loaded Bone Cement.

OBJECTIVE: To investigate the biomechanical and elution properties of meropenem-loaded bone cement. METHODS: Bone cement (Palacos LV) with 5% (2 g/4 0g), 10% (4 g/40 g), and 15% (6 g/40 g) meropenem; 5% (2 g/40 g) and 10% (4 g/40 g) vancomycin; and blank bone cement were prepared in a total of six groups named A2, A4, A6, B2, B4, and A0 (antibiotic-free). 36 cylinder specimens (6-mm diameter and 12-mm height) of all six groups were molded for a compression test. After the compression test, because of mechanical properties below the ISO standard requirements, groups B2, B4 were not subjected to a bending test. So a total of 24 rectangular strip specimens (10-mm width, 75-mm length, and 3.3-mm thickness) for groups A2, A4, A6 and A0 were molded for the bending test. Between-group differences of compressive strength, bending strength and bending modulus were analyzed. The meropenem standard was prepared as a series of standard solutions to calculate the standard curve. At a constant temperature of 37 °C, separately, meropenem-loaded bone cement cylinder specimens (12 mm in diameter and 17 mm in length) of A2, A4 and A6 were serially immersed in saline solution without stirring. The eluent drug concentration at 24, 48, 72 h and 6, 12, 24 days was measured and the drug concentration-time curve of meropenem was constructed. RESULTS: With the exception of groups B2 and B4, all cements compressive strength values were well above the minimum requirement of the ISO 5833 standard (70 MPa). The compressive strength and bending strength values of group A4 were higher than those of group A0 (P < 0.05), but no difference was found between the A0, A2 and A6 groups (P > 0.05). There were no intergroup differences of bending modulus between the A0, A2, A4 and A6 groups (P > 0.05). A standard curve of meropenem was obtained and a regression equation was constructed: Y = 15.0265 X + 13.5218, r = 1.00. At 37 °C, the release of meropenem was rapid during the first 48 h for all A2, A4, A6 samples, and subsequent release continued to decrease. CONCLUSION: When adding up to 15% (6 g/40 g) meropenem to the bone cement, the biomechanical properties were not reduced, and bone cement with 10% (4 g/40 g) meropenem had the best performance. At a constant temperature of 37°C, meropenem can be released from bone cement for up to 24 days.

Risk Factors and Outcomes for Preoperative Asymptomatic Pulmonary Embolism in Patients Aged 60 Years and Over with Hip Fracture.

OBJECTIVE: To investigate the risk factors for, and outcomes of, preoperative asymptomatic pulmonary embolism (PE) in patients ≥60 years old following delayed operation for hip fracture. METHODS: From March 2017 to December 2018, 90 patients aged ≥60 years with hip fracture who suffered a delay in surgery were recruited to this prospective study following admission to our hospital. Computed tomography pulmonary angiography (CTPA) was used to detect preoperative asymptomatic PE and calculated its incidence. Time from injury to admission, baseline characteristics, medical comorbidities, and blood biomarker levels were evaluated as potential risk factors. Logistic regression analysis was used to identify risk factors. Mortality and major bleeding events were recorded and compared between individuals with PE and without. Data were analyzed by t-test, Mann-Whitney U test, χ2 test, Fisher's exact test, and logistic regression analysis. RESULTS: The incidence of preoperative asymptomatic PE was 18.9% (17/90 patients). In the univariate analysis, the risk factors for preoperative asymptomatic PE were male sex, hypertension, cerebrovascular accident, smoking, plasma D-dimer level, potassium level, urea level, creatinine level, and cysteine level. Multivariate logistic regression analysis showed that the risk of preoperative asymptomatic PE was higher in patients with hypertension (odds ratio [OR] = 10.048; 95% confidence interval [CI], 1.118-90.333), cerebrovascular accident (OR = 20.135; 95% CI, 1.875-216.164), smoking (OR = 48.741; 95% CI, 4.155-571.788), high plasma D-dimer levels (OR = 1.200; 95% CI, 1.062-157.300), and high plasma potassium levels (OR = 12.928; 95% CI, 1.062-157.300). All patients were followed up for 21.0 months (range, 2 to 36 months). Mortality within the first year postoperatively was higher in patients with PE (29.41% vs 9.59%, P = 0.046). CONCLUSIONS: In view of the high incidence of preoperative asymptomatic PE and the inferior prognosis in individuals with PE, routine CTPA examination for preoperative asymptomatic PE could be useful for patients aged ≥60 years with hip fracture for whom surgery is delayed.

Risk factors of perioperative blood transfusion in elderly patients with femoral intertrochanteric fracture.

This study aimed to discuss the risk factors of perioperative blood transfusion after the application of proximal femoral nail antirotation (PFNA) in the treatment of elderly patients with femoral intertrochanteric fracture (FIF). Moreover, this study also aimed to analyze the causes of perioperative blood transfusion and provide guidance for clinical treatment.Records of elderly patients with FIF who were treated with PFNA in our hospital from September 2014 to May 2017 were reviewed. They were divided into transfused and nontransfused groups. The Student t test, Chi-squared test, and Fisher exact test were used in univariate analysis of 11 variables. Multivariate logistic regression analysis was performed to analyze the possible risk factors associated with postoperative blood transfusion after the application of PFNA in elderly patients with FIF. Correlations were sought using the Spearman rank correlation analysis.The univariate analysis showed that age, sex, type of fracture, admission hemoglobin (Hb), admission albumin, and intraoperative blood loss were significantly associated with perioperative blood transfusion (P = .000, .019, .000, .000, .000, and .007, respectively). The multivariate logistic regression analysis demonstrated that age (P = .019, odds ratio [OR] = 1.062), type of fracture (P = .001, OR = 4.486), and admission Hb (P = .000, OR = 0.883) were independent risk factors of postoperative blood transfusion. We found a significant positive correlation between perioperative blood transfusion and age (r = 0.264, P = .000) and type of fracture (r = 0.409, P = .000), but a negative correlation between perioperative blood transfusion and admission Hb (r = -0.641, P = .000).The main factors affecting perioperative blood transfusion are age, fracture type, and admission Hb. These results indicate that, in high-risk patients who are older in age, more unstable fractures, and lower admission Hb, monitoring Hb concentrations during the perioperative period is important to correct severe anemia in a timely manner and avoid exacerbating existing underlying diseases and inducing severe complications.