The increasing numbers of total joint replacements and related implant-associated infections demand solutions, which can provide a high-dose local delivery of antibiotics. Antibiotic-loaded bone cement (ALBC) is an accepted treatment method for infected joint arthroplasties. The mechanical properties of low-dose gentamicin-loaded bone cement (BC) in medium- and high-viscosity versions were compared to unloaded BC using a vacuum mixing system. As an additional control group, manual mixed unloaded BC was used. In a uniaxial compression test, ultimate compressive strength, compressive yield strength, and compression modulus of elasticity, as well as ultimate and yield strain, were determined according to ISO 5833-2022 guidelines. All groups exceeded the minimum compressive strength (70 MPa) specified in the ISO 5833 guidelines. Both ALBC groups showed a similar ultimate compressive and yield strength to the unloaded BC. The results showed that vacuum mixing increased the compression strength of BC. ALBC showed similar compressive strength to their non-antibiotic counterparts when vacuum mixing was performed. Added low-dose gentamicin acted as a plasticizer on bone cement. From a biomechanical point of view, the usage of gentamicin-based ALBC formulations is viable.
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Cementoplasty has been successfully used for treating fractures in various parts of the human body, although the use in weight-bearing long bones is a subject of controversial debate. Strategies to improve the mechanical properties of polymethylmethacrylate-based bone cement (BC) comprise changing the chemical composition or the application of metal reinforcement strategies. In clinical practice reinforced bone cement is used despite biomechanical basic research regarding this topic being scare. The aim of the present study was to evaluate the biomechanical properties of two different reinforcement strategies against non-reinforced polymethylmethacrylate-based BC subjected to bending stress. In this controlled comparative laboratory analysis, we evaluated two types of reinforcement strategies in comparison to a control group (C). BC was reinforced with a Kirschner wire (group CW) or with a prestressed twinned steel cable (group CC); control group C was native polymethylmethacrylate-based BC. All the samples were prepared using a custom-made mould and underwent 4-point bending stress until fracture using a testing machine. Flexural strength, maximum strain, and Young's modulus were assessed for the three groups and compared using the Kruskal‒Wallis test. The mean flexural strength in MPa was 48 ± 12 in C, 64 ± 6 in CW, and 63 ± 14 in CC. A significantly greater flexural strength of + 33% was found in both reinforced groups than in the C group (C vs. CW p = 0.011, C vs. CC p = 0.023). Regarding the flexural strength, no statistically significant difference could be found between the two reinforcement strategies CW and CC (p = 0.957). The maximum strain was 3.0% in C and CW and 3.8% in CC and no difference between the three groups was observed (p = 0.087). The Young's modulus in GPa was 2.7 for C, 2.8 for CW, and 2.4 for CC. The comparison of Young's module using the Kruskal-Wallis test showed no statistically significant difference between CC, CW and C (p = 0.051). We detected an improvement in flexural strength in the reinforced groups. Both reinforcement through K-wire and prestressed cables promoted increased flexural strength. Furthermore, less material failure was observed with possible realignment and subsequent residual stability despite bone cement fracture. From a biomechanical view, the concept of macro metal reinforcement of osteoplasty is viable.
While percutaneous (reinforced) cementoplasty is common for the treatment of vertebral fractures, its use in weight bearing long bones is a subject of controversial debate. The aim of the present study was to evaluate the biomechanical properties of two different reinforcement strategies of bone cement (BC) undergoing bending stress.In this controlled laboratory comparison, we analysed three groups (CW, CC, C) á 10 samples. CW had a 2 mm Kirschner wire (K-wire) embedded and CC was reinforced with a pre-stressed 2 mm twined steel cable, control group C was native BC. All samples underwent 4-point bending stress until fracture and flexural strength, maximum strain, and modulus of elasticity were assessed.Mean flexural strength in MPa was 48 ± 12 in C, 64 ± 6.0 in CW, and 63 ± 14 in CC. A statistically significant higher flexural strength in both reinforced groups of + 33 % compared to C was found. Maximum strain was 3.0 % in C and CW and 3.8 % in CC. Modulus of elasticity in GPa was 2.7 in C, 2.8 in CW, and 2.4 in CC. No significant statistical difference between the groups was found in maximum strain, and modulus of elasticity.We could detect an improvement in flexural strength in the reinforced groups. Both reinforcement through K-wire and pre-stressed cable led to an increased flexural strength. Patients with metastatic bone disease may benefit from reinforced cementoplasty, with pre-stressed cables an anatomical axis may be facilitated despite BC failure.
Abstract Purpose Upper tract urothelial carcinoma (UTUC) represents an often aggressive malignancy associated with poor prognosis. Therefore, finding reliable prognostic biomarkers in patients undergoing curative surgery for improved risk stratification is crucial. We evaluated the prognostic value of the Fibrinogen/C-reactive protein (FC)-score in a cohort of surgically treated UTUC patients. Methods 170 patients with radiologically and histologically verified UTUC who underwent radical curative surgery between 1990 and 2020, were included. The FC-score was calculated for each patient, with patients receiving 1 point each if Fibrinogen and/or CRP levels were elevated above the 25th or 75th percentile, respectively. Patients were divided into three subgroups according to their FC-score of 0, 1 or 2 point(s). Kaplan–Meier analysis, uni- and multivariable Cox proportional hazard models were implemented. We determined cancer-specific survival (CSS) as primary endpoint, whereas overall survival (OS) and recurrence-free survival (RFS) were considered secondary endpoints. Results High FC-score (2 points) was significantly associated with adverse histological features such as vascular invasion (OR = 4.08, 95%CI 1.18–14.15, p = .0027) and tumour necrosis (OR = 6.67, 95%CI 1.35–32.96, p = 0.020). Both, uni- and multivariable Cox proportional hazard models showed the FC-score as a significant predictor for CSS (univariable analysis: FC-score = 1: HR = 1.90, 95%CI 0.92–3.93, p = 0.085 | FC-score = 2: HR = 2.86, 95%CI 1.22–6.72, p = 0.016). Furthermore, in univariable analysis, patients with higher FC-score had significantly shorter OS (FC-score = 1: HR = 1.32, 95%CI 0.70–2.49, p = 0.387 | FC-score = 2: HR = 2.19, 95%CI 1.02–4.67, p = 0.043). However, this did not prevail in multivariable analysis. Conclusion The FC-score represents a novel potential biomarker in patients with UTUC undergoing radical curative surgery.
