Infection incidence for total hip and knee arthroplasty (THA and TKA, respectively) is between 0.2% and 5% and results in approximately 100,000 device failures per year in the United States. ...Treatment requires prolonged systemic antibiotic therapy with additional surgical revisions. As a prophylactic measure against infection, antibiotics can be incorporated into bone cement during THA and TKA to provide drug administration at the implant site. Antibiotics in bone cement are only effective if they can elute out of the cement at a concentration that is active against common organisms. There is evidence that added antibiotics may affect the cement's mechanical properties, especially at higher dosages. The purposes of this investigation were to (i) determine the mechanical properties of a commercially available bone cement with the addition of vancomycin, (ii) determine the release characteristics of vancomycin added to bone cement, and (iii) evaluate eluted vancomycin efficacy at eliminating some of the most common causative orthopedic implant pathogens. Palacos bone cement was impregnated with incrementally larger clinically relevant weight percentages of vancomycin. Vancomycin is a treatment standard for invasive gram-positive infections, and Palacos cement is one of the most commonly used bone cements. After 21 days of curing in PBS, added masses of vancomycin greater than 0.5 g per 40.0 g cement packet decreased the cement's compressive yield strength to below ISO standard. The addition of vancomycin reduced the bone cement's mechanical properties in compression more than in bending. Vancomycin eluted from Palacos with a steady rise in eluted volume up to 8 days, after which non-therapeutic elution concentrations were observed up to a 60-day end point. The eluted concentration from samples with greater than 0.25 g vancomycin per Palacos packet was sufficient to eliminate a 10
colony forming unit per mL (CFU/mL) initial inoculum of S. aureus, including methicillin-resistant S. aureus (MRSA). However, none of the tested dosages were able to fully clear a 10
CFU/mL initial inoculum of a known high biofilm producing strain of S. epidermidis. When used for infection prophylaxis at the time of THA and TKA, the findings of this study do not support the addition of more than 0.5 g vancomycin to a 40 g packet of Palacos cement due to a reduction in compression yield strength below ISO standards. Vancomycin doses up to 0.5 g were shown to elute from the bone cement matrix and are effective at treating bacterial infections of 10
CFU/mL in bacterial strains of S. aureus, but may have limited effect against high-biofilm producing strains including S. epidermidis.
Prosthetic joint infection (PJI) is one of the most devastating failures in total joint replacement (TJR). Infections are becoming difficult to treat due to the emergence of multi-drug resistant ...bacteria. These bacteria produce biofilm on the implant surface, rendering many antibiotics ineffective by compromising drug diffusion and penetration into the infected area. With the introduction of new antibiotics there is a need to create benchmark data from the traditional antibiotic loaded bone cements. Vancomycin, one of the commonly used antibiotics, shows activity against Methicillin-resistant Staphylococcus aureus (MRSA) and S.epidermidis. In our study, vancomycin added to bone cement was evaluated for elution properties, antimicrobial properties, and mechanical properties of the bone cement. Vancomycin at five different loading masses (0.125, 0.25, 0.5, 1.0 and 2.0 g) was added to 40 g of Simplex™ P cement. Addition of vancomycin affected the mechanical properties and antimicrobial activity with significant differences from controls. Flexural and compression mechanical properties were compromised with added vancomycin. The flexural strength of samples with added vancomycin of 0.5 g and greater were not greater than ISO 5833 minimum requirements. 2.0 g of vancomycin added to bone cement was able to eliminate completely the four bacterial strains tested. 2.0 g of vancomycin also showed the highest mass elution from the cement over a 60-day period. Given the reduced flexural strength in samples with 0.5 g and greater of added vancomycin and the inability of vancomycin in amounts less than 2.0 g to eliminate bacteria, this study did not find an ideal amount of vancomycin added to Simplex™ P that meets both strength and antibacterial requirements.
In this article, we report data on the antibiotic elution and efficacy, and mechanical properties of Palacos bone cement with different amounts of added vancomycin (0.0, 0.125, 0.25, 0.5, 1.0, ...2.0 g), see “Vancomycin elution, activity and impact on mechanical properties when added to orthopedic bone cement” (Bishop et al., 2018) 1. Mechanical testing was performed for four-point bending, compression, and fracture toughness. The release characteristics of vancomycin was recorded for up to 60 days to estimate the elution profile. The eluted vancomycin efficacy at eliminating the four most common causative orthopedic implant pathogens is also reported.
Introduction:
With the advent of complex treatment techniques like volumetric modulated arc therapy, there has been increasing interest in treatment planning technologies aimed at reducing planning ...time. One of these such technologies is auto-planning, which is an automated planning module within Pinnacle3. This study seeks to retrospectively evaluate the dosimetric quality of auto-planning-derived treatment plans as they compare to manual plans for intact prostate, prostate and lymph nodes, and brain treatment sites.
Materials and Methods:
Previous clinical plans were used to generate site-specific auto-planning templates. These templates were used to compare the 3 evaluated treatment sites. Plans were replanned using auto-planning and compared to the clinically delivered plans. For the planning target volume, the following metrics were evaluated: homogeneity index, conformity index, D2cc, Dmean, D2%, D98%, and multiple dose fall-off parameters. For the organs at risk, D2cc, Dmean, and organ-specific clinical metrics were evaluated. Statistical differences were evaluated using a Wilcoxon paired signed-rank test with a significance level of 0.05. Statistically significant (P < 0.05) differences were noted in organs at risk sparing.
Results:
For the prostate, there was as much as 6.8% reduction in bladder Dmean and 23.5% reduction in penile bulb Dmean. For the prostate + lymph nodes, decreases in Dmean values ranging from 4.1% in the small bowel to 22.3% in the right femoral head were observed. For brain, significant improvements were observed in Dmax and Dmean to most organs at risk.
Conclusion:
Our study showed improved organs at risk sparing in most organs while maintaining planning target volume coverage. Overall, auto-planning can generate plans that delivered the same target coverage as the clinical plans but offered significant reductions in mean dose to organs at risk.
The complexities of the role of leadership in Public-Private Partnerships (PPPs) in the various sectors is little understood. This study explored the roles and characteristics of leadership in PPPs ...with business, educational, political, and religious leaders in meeting the needs of impoverished youths in Richland County, South Carolina. The research questions explored what leadership characteristics existed in PPPs’ leadership teams and their ability to impact delivery outcome. A qualitative case study approach was utilized with the theoretical framework based on Burns’ (1978) transformational leadership styles. A purposive sampling strategy identified 20 people who played a vital role in the leadership of PPPs. All data were inductively coded and then subjected to a constant comparative method of analysis. The analysis revealed a strong relationship between servant leadership attributes exhibited by the leadership team and the project team’s ability to traverse the partnership challenges. Data analysis indicated the necessity of effective transformational leadership, precisely, the attributes of understanding and empathy. Implications for positive social change from this study may lead to improved leadership within PPPs to deliver outcomes and better utilization of taxpayer funds to administer social programs for impoverished youths in Richland County, South Carolina.
Prosthetic joint infection (PJI) is the most common reason for early revision of total joint replacements. In these applications, antibiotic-loaded bone cement (ALBC) is widely used both as a ...prophylaxis and treatment/management for PJI. However, over time, the bacterial strains most frequently associated with PJI have become resistant to the antibiotics commonly used in ALBC's such as gentamicin and vancomycin. The present study was an in vitro evaluation of telavancin-loaded Palacos R and Simplex P cements, with different amounts of the antibiotic added to 40 g of cement powder: 0.125, 0.25, 0.5, 1.0, and 2.0 g.
Telavancin elution was measured from each cement over 60 days. The efficacy of the eluted telavancin in eliminating four bacterial strains associated with PJI (MSSA, MRSA, and S. epidermidis) was determined. Mechanical tests, four-point bend, compression, and fracture toughness, were performed.
In this in vitro study, the higher doses of telavancin increased telavancin release, and Palacos exhibited better elution than did Simplex. Similarly, the addition of 2 g of telavancin to the Palacos increased the efficacy of the ALBC for preventing bacterial colonization and biofilm formation. However, the mechanical performance of the bone cement containing telavancin was significantly reduced after wet curing, with flexural and compressive strength of the cements weakening. Moreover, Palacos that contained telavancin resulted in higher fracture toughness than did Simplex. Therefore, incorporating telavancin into Palacos for use in total joint replacement surgery demonstrated better performance than Simplex but further study is needed to improve the detrimental effects on mechanical properties.
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Contact charge electrophoresis (CCEP) uses steady electric fields to drive the continuous, oscillatory motion of conductive particles and droplets between two or more electrodes. These rapid ...oscillations can be rectified to direct the motion of objects within microfluidic environments using low-power, dc voltage. Here, we compare high precision experimental measurements of CCEP within a microfluidic system to equally detailed theoretical predictions on the motion of a conductive particle between parallel electrodes. We use a simple, capillary microfluidic platform that combines high-speed imaging with precision electrical measurements to enable the synchronized acquisition of both the particle location and the electric current due to particle motion. The experimental results are compared to those of a theoretical model, which relies on a Stokesian dynamics approach to accurately describe both the electrostatic and hydrodynamic problems governing particle motion. We find remarkable agreement between theory and experiment, suggesting that particle motion can be accurately captured by a combination of classical electrostatics and low-Reynolds number hydrodynamics. Building on this agreement, we offer new insight into the charge transfer process that occurs when the particle nears contact with an electrode surface. In particular, we find that the particle does not make mechanical contact with the electrode but rather that charge transfer occurs at finite surface separations of >0.1 μm by means of an electric discharge through a thin lubricating film. We discuss the implications of these findings on the charging of the particle and its subsequent dynamics.
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