Silver carboxylate-TiO2/polydimethyl siloxane is a safe and effective antimicrobial with significant wound care potential.

Introduction: With the rise in antibiotic resistance, new methodologies are needed to combat musculoskeletal infections. Silver is an antimicrobial that can be synthesized in different forms, but its pharmacokinetics are difficult to control. This study details the antibacterial efficacy and cellular cytotoxicity of a formulation consisting of silver carboxylate (AgCar) released through a titanium dioxide/polydimethylsiloxane matrix with a predictable release profile on Pseudomonas aeruginosa, Acinetobacterium baumannii, and human-derived primary osteoblasts. Methods: Through an Institutional Animal Care and Use Committee and IRB-approved protocol, AgCar was applied to live Yucatan porcine skin and histologically analyzed for skin penetration. Graphite Furnace Atomic Absorption Spectroscopy (GFAAS) was used to measure elution of AgCar. Dose-response curves were generated through optical density to assess potency. Finally, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to quantify the cellular cytotoxicity of the novel formulation. The results were subject to statistical analysis using analysis of variance and post hoc Tukey tests. Results: The silver carboxylate coating demonstrated deep penetration into the epithelium at the level of the deep pilosebaceous glands in animal models. GFAAS testing demonstrated the extended elution profile of silver carboxylate over 96 hours, while 100% silver with no titanium dioxide-polydimethylsiloxane matrix fully eluted within 48 hours. 10x silver carboxylate demonstrated superior antimicrobial activity to antibiotics and other silver formulations and showed minimal cytotoxicity compared with other silver formulations. Discussion/Clinical Relevance: Current antimicrobial therapies in wound care and surgical antisepsis, such as chlorhexidine gluconate, have pitfalls including poor skin penetration and short duration of efficacy. The broad antimicrobial activity, extended elution, and deep skin penetration of this AgCar formulation show great promise for surgical site infection and wound care treatment. Novel technology to fight the growing threat of microbial resistance should be at the forefront of orthopaedic surgical site infection prevention and treatment.

The Immediate Impact of Total Knee Arthroplasty Removal From the Medicare Inpatient-Only List on Patient Derived Functional Outcomes and Hospital Satisfaction.

BACKGROUND: Total knee arthroplasty (TKA) is the standard of treatment for end-stage knee osteoarthritis. On January 1, 2018, the Centers for Medicare and Medicaid (CMS) officially removed TKA from their inpatient-only list. The clinical impact of this change is not fully understood yet. METHODS: Electronic records were retrospectively reviewed for patients who underwent TKA between January 1 to June 30, 2017, or January 1 to June 30, 2018. Patients completed Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement surveys which assessed patient reported outcomes prior to and following TKA. Hospital statistics for the 2 time points were determined and compared. This was a single institution study resulting in 351 patients in the pre-CMS change group and 350 patients in the post-CMS change group. RESULTS: Analysis of the pre-CMS and post-CMS transition cohorts indicated no significant difference in activities of daily living (ADLs), pain, or pain catastrophizing scale preoperatively or 12-months postoperatively. Additionally, there was no difference in the median change between preoperative and postoperative ADL scores (P = .866), yet pain scores approached significance with a P value of .054. The pre-CMS transition group stayed significantly longer in the hospital postoperatively and was more commonly discharged to a skilled nursing facility. No difference was seen in 30-day readmission rates (P = .253). CONCLUSIONS: Results showed that patients had similar scores for ADL, quality of life, pain, and pain catastrophizing 12-months following their TKA. Movement of TKA from the Medicare inpatient only list did not have an immediate negative impact for patient reported outcomes and 30-day readmissions at our institution in the 6-month transition period.

Mechanically stable rifampin antibiotic cement inhibits Pseudomonas aeruginosa biofilm surface growth.

Rifampin has been proven to be effective in the treatment of prosthetic infections due to its ability to intercalate into biofilms. The use of rifampin in antibiotic spacers is not well described, which would be especially important in the local periprosthetic environment where parenteral doses have poor penetration. The null hypothesis tests if rifampin use in polymethyl methacrylate (PMMA) cement will show no clinically significant impact on mechanical strength at antibiotic concentrations that remain bactericidal. Test antibiotic cement samples supplemented with 0, 30, 50, 100, 150, or 200 mg of rifampin into a standard 40 g bag were tested for compression to failure using published ASTM standards. The samples were then inoculated with Pseudomonas aeruginosa and either evaluated for lipopolysaccharide (LPS) presence as a marker of biofilm or tested by elution as the Kirby Bauer assay. Rifampin concentrations of 30 and 50 mg, showed no statistically different mechanical characteristics from control PMMA (p > 0.05). The 100-mg sample fell within the acceptable range of compressive strength and had significantly less LPS and bacterial presence compared to the control at 12 and 24 h. The ability of PMMA with 100 mg of rifampin to maintain its structural integrity and have significant bacterial inhibition at 12 and 24 h makes it a great candidate as an antibiotic bone cement additive. PMMA loaded with up to 100 mg of rifampin shows promise in the treatment and prevention of periprosthetic joint infection for total knee and total hip arthroplasty.

Medial Calcar Restoration Using Femoral Head Autograft in Conversion Hip Arthroplasty for Failed Fixation after an Unstable Intertrochanteric Hip Fracture: A Case Report and Technique Description.

Introduction: The calcar femorale helps manage compressive loads on the femoral head and is an essential component in determining intertrochanteric (IT) femur fracture stability. Fracture fixation can be complicated when primary fixation techniques, such as cephalomedullary nailing fail. Unstable IT femur fractures involving disruption of the medial calcar present additional fixation challenges. Case Report: This case reports a patient with unstable IT fracture due to medial calcar disruption that experienced failure of a short cephalomedullary nail. Secondary fixation involved total hip arthroplasty (THA) with medical calcar reconstruction using femoral head autograft. Outcomes were good at 2-year follow-up with a full return to baseline activities. Conclusion: The results indicate that femoral head autografting can be a viable option, with good outcomes, for medial calcar reconstruction in cases of failed IT fracture fixations without calcar support, converted to THA.

Local anesthetic with monitored anesthesia care in cephalomedullary nailing of proximal femur fractures.

INTRODUCTION: Proximal femur fractures have high rates of morbidity, mortality, and perioperative complications. Limiting anesthesia, especially in the elderly population, is a priority from a medical perspective. The goal of the current study is to present a technique of using local anesthetic with monitored anesthesia care (MAC) for the fixation of intertrochanteric (IT) femur fractures with cephalomedullary nailing (CMN), provide early clinical results in a small series of patients, and evaluate the safety, efficiency, and anesthetic efficacy of our technique. HYPOTHESIS: The use of only local anesthetic with MAC for the fixation of IT fractures is safe and leads to decreased operative times when compared to spinal and general anesthesia. MATERIALS AND METHODS: Patients undergoing cephalomedullary nailing (CMN) with a long nail for IT femur fractures by a single surgeon from January 2020 to June 2021 were identified retrospectively from a prospectively-collected patient registry. Patient demographics, operative time, length of hospital stay, perioperative medication use, and complications were collected. Analysis of variance, Chi2, linear regression, and two-sampled T-tests were performed to analyze potential differences between the local anesthesia group and the general or spinal anesthesia group. RESULTS: Thirty-seven patients were identified. Eleven patients underwent CMN using local anesthesia with MAC, 11 using spinal anesthesia, and 15 using general anesthesia. The local anesthesia group demonstrated significantly lower operating room times and anesthesia induction to incision time compared to other anesthesia techniques. The local anesthesia group also trended towards less need for vasopressors during surgery and less postoperative delirium. No differences were identified in intraoperative narcotic use, complications, patient mortality, or hospital readmissions. CONCLUSIONS: Local anesthesia with MAC for the treatment of IT fractures with CMN was associated with decreased operating room times and had similar complication rates including blood transfusions, readmissions, and mortalities, when compared to spinal and general anesthesia. LEVEL OF EVIDENCE: III, therapeutic.

Silver Carboxylate-Eluting Titanium-Dioxide Polydimethylsiloxane Coating Inhibits Multi-Drug-Resistant Acinetobacterium baumannii and Vancomycin-Resistant Enterococcus faecalis Adherence and Proliferation on Orthopedic Trauma Fixation and Spinal Fusion Materials.

Background: Vancomycin-resistant Enterococcus faecalis and multi-drug-resistant (MDR) Acinetobacter baumannii are rising contributors to spinal fusion and fracture-associated infections (FAI), respectively. These MDR bacteria can form protective biofilms, complicating traditional antibiotic treatment. This study explores the effects of the antibiotic-independent antimicrobial silver carboxylate (AgCar)-doped coating on the adherence sand proliferation of these pathogens on orthopedic implant materials utilized in spinal fusion and orthopedic trauma fixation. Methods: Multi-drug-resistant Acinetobacter baumannii and vancomycin-resistant Enterococcus faecalis were inoculated on five common implant materials: cobalt chromium, titanium, titanium alloy, polyether ether ketone, and stainless steel. Dose response curves were generated to assess antimicrobial potency. Scanning electron microscopy and confocal laser scanning microscopy were utilized to characterize and quantify growth and adherence on each material. Results: The optimal AgCar concentration was a 95% titanium dioxide (TiO2)-5% polydimethylsiloxane (PDMS) matrix combined with 10 × silver carboxylate, which inhibited bacterial proliferation by 89.40% (p = 0.001) for MDR Acinetobacter baumannii and 84.02% (p = 0.001) for vancomycin-resistant Enterococcus faecalis compared with uncoated implants. A 95% TiO2-5% PDMS matrix combined with 10 × AgCar was equally effective at inhibiting bacterial proliferation across all implant materials for MDR Acinetobacter baumannii (p = 0.19) and vancomycin-resistant Enterococcus faecalis (p = 0.07). A 95% TiO2-5% PDMS matrix with 10 × AgCar is effective at decreasing bacterial adherence of both MDR Acinetobacter baumannii and vancomycin-resistant Enterococcus faecalis on implant materials. Conclusions: Application of this antibiotic-independent coating for surgery in which these implant materials might be used may prevent adherence, biofilm formation, spinal infections, and FAI by MDR Acinetobacter baumannii and vancomycin-resistant Enterococcus faecalis.

Silver as an Antibiotic-Independent Antimicrobial: Review of Current Formulations and Clinical Relevance.

Background: The increase of multi-drug-resistant organisms has revived the use of silver as an alternative antibiotic-independent antimicrobial. Although silver's multimodal mechanism of action provides low risk for bacterial resistance, high local and uncontrolled concentrations have shown toxicity. This has resulted in efforts to develop novel silver formulations that are safer and more predictable in their application. Optimization of silver as an antimicrobial is crucial given the growing resistance profile against antibiotics. This article reviews formulations of silver used as antimicrobials, focusing on the mechanisms of action, potential for toxicity, and clinical applications. Methods: A search of four electronic databases (PubMed, Embase, MEDLINE, and Cochrane Library) was conducted for relevant studies up to January 2022. Searches were conducted for the following types of silver: ionic, nanoparticles, colloidal, silver nitrate, silver sulfadiazine, silver oxide, silver carboxylate, and AQUACEL® (ConvaTec, Berkshire, UK). Sources were compiled based on title and abstract and screened for inclusion based on relevance and study design. Results: A review of the antimicrobial activity and uses of ionic silver, silver nanoparticles, colloidal silver, silver nitrate, silver sulfadiazine, silver oxide, Aquacel, and silver carboxylate was conducted. The mechanisms of action, clinical uses, and potential for toxicity were studied, and general trends between earlier and more advanced formulations noted. Conclusions: Early forms of silver have more limited utility because of their uncontrolled release of silver ions and potential for systemic toxicity. Multiple new formulations show promise; however, there is a need for more prospective in vivo studies to validate the clinical potential of these formulations.