In vitro and in vivo assessment of extended duration cathodic voltage-controlled electrical stimulation for treatment of orthopedic implant-associated infections.

Effective treatment of orthopedic implant-associated infections (IAIs) remains a clinical challenge. The in vitro and in vivo studies presented herein evaluated the antimicrobial effects of applying cathodic voltage-controlled electrical stimulation (CVCES) to titanium implants inoculated with preformed bacterial biofilms of methicillin-resistant Staphylococcus aureus (MRSA). The in vitro studies showed that combining vancomycin therapy (500 µg/mL) with application of CVCES at -1.

Reverse total shoulder arthroplasty baseplate stability with locking vs. non-locking peripheral screws.

Background: There are many options for glenosphere baseplate fixation commercially available, yet there is little biomechanical evidence supporting one type of fixation over another. In this study, we compared the biomechanical fixation of a reverse total shoulder glenoid baseplate secured with locking or non-locking peripheral screws.

Methods: Both a non-augmented mini baseplate with full backing support and an augmented baseplate were testing after implantation in solid rigid polyurethane foam.

Reverse Total Shoulder Arthroplasty Baseplate Stability in Superior Bone Loss With Augmented Implant.

Background: Glenoid bone loss is commonly encountered in cases of rotator cuff tear arthropathy and can create challenges during reverse shoulder arthroplasty. In this study, we sought to investigate the biomechanical properties of a new treatment option for superior glenoid defect, an augmented reverse total shoulder baseplate.

Methods: Three conditions were examined: non-augmented baseplate without defect, non-augmented baseplate with defect, and augmented baseplate with defect.

Effect of radio frequency glow-discharge treatment of titanium on human gingival fibroblasts as a function of distance.

The mechanical stability and long-term success of an implant depends on the early healing phase and osseointegration of the bone around it. In addition, a healthy gingival tissue around the implant acts as a barrier that prevents bacteria and pathological byproducts from reaching the implant site. This study investigated the in-vitro attachment and spreading of human gingival fibroblasts (HGF) on bacterial grade polystyrene (PS) at different distances from radio-frequency glow-discharge (RFGD)-treated commercially pure titanium (cpTi) specimens.

Electrochemical methods to enhance osseointegrated prostheses.

Osseointegrated (OI) prosthetic limbs have been shown to provide an advantageous treatment option for amputees. In order for the OI prosthesis to be successful, the titanium implant must rapidly achieve and maintain proper integration with the bone tissue and remain free of infection. Electrochemical methods can be utilized to control and/or monitor the interfacial microenvironment where the titanium implant interacts with the biological system (host bone tissue or bacteria).

Antibiotics Enhance Prevention and Eradication Efficacy of Cathodic-Voltage-Controlled Electrical Stimulation against Titanium-Associated Methicillin-Resistant Staphylococcus aureus and Pseudomonas aeruginosa Biofilms.

Periprosthetic joint infection (PJI) develops clinically, even with antibiotic treatment, and methicillin-resistant (MRSA) and are predominant causes of these infections. Due to biofilm formation, antibiotic treatment for patients with PJI can perpetuate resistance, further complicating the use of noninvasive treatments. This study evaluated cathodic-voltage-controlled electrical stimulation (CVCES) of titanium, in combination with a clinically relevant antibiotic, to synergistically prevent MRSA and PJIs by inhibiting bacterial adherence or as a treatment for eradicating established biofilms.

Bio-Corrosion of Magnesium Alloys for Orthopaedic Applications.

Three Mg alloys, Mg-1.34% Ca-3% Zn (MCZ), Mg-1.34% Ca-3% Zn-0.

Reverse total shoulder glenoid baseplate stability with superior glenoid bone loss.

Background: Superior wear of the glenoid bone is common in patients with rotator cuff arthropathy. This can become a treatment challenge for patients who require shoulder arthroplasty. In reverse shoulder arthroplasty (RSA), glenoid bone loss may affect the stability of baseplate fixation.

Magnesium alloy AZ91 exhibits antimicrobial properties in vitro but not in vivo.

Magnesium alloys hold great promise for developing orthopedic implants that are biocompatible, biodegradable, and mechanically similar to bone tissue. This study evaluated the in vitro and in vivo antimicrobial properties of magnesium-9%aluminum-1%zinc (AZ91) and commercially pure titanium (cpTi) against Acinetobacter baumannii (Ab307). The in vitro results showed that as compared to cpTi, incubation with AZ91 significantly reduced both the planktonic (cpTi = 3.

Effects of simulated inflammation on the corrosion of 316L stainless steel.

Stainless steel alloys, including 316L, find use in orthopaedics, commonly as fracture fixation devices. Invasive procedures involved in the placement of these devices will provoke a local inflammatory response that produces hydrogen peroxide (HO) and an acidic environment surrounding the implant. This study assessed the influence of a simulated inflammatory response on the corrosion of 316L stainless steel.

The effect of fretting associated periodic cathodic potential shifts on the electrochemistry and in vitro biocompatibility of commercially pure titanium.

This study explored how periodic cathodic polarization of commercially pure titanium (cpTi) alters its electrochemical properties and biocompatibility. MC3T3-E1 preosteoblast cells were cultured directly on cpTi samples and maintained at open circuit potential (OCP) for 24 h followed by an additional 24-h sequence of periodic cathodic polarization to -1000 or -750 mV (vs. Ag/AgCl) for 1 s followed by a 5-s recovery at OCP.

Cathodic Voltage-controlled Electrical Stimulation Plus Prolonged Vancomycin Reduce Bacterial Burden of a Titanium Implant-associated Infection in a Rodent Model.

Background: Cathodic voltage-controlled electrical stimulation (CVCES) of titanium implants, either alone or combined with a short course of vancomycin, has previously been shown to reduce the bone and implant bacterial burden in a rodent model of methicillin-resistant Staphylococcus aureus (MRSA) implant-associated infection (IAI). Clinically, the goal is to achieve complete eradication of the IAI; therefore, the rationale for the present study was to evaluate the antimicrobial effects of combining CVCES with prolonged antibiotic therapy with the goal of decreasing the colony-forming units (CFUs) to undetectable levels.

Questions/purposes: (1) In an animal MRSA IAI model, does combining CVCES with prolonged vancomycin therapy decrease bacteria burden on the implant and surrounding bone to undetectable levels? (2) When used with prolonged vancomycin therapy, are two CVCES treatments more effective than one? (3) What are the longer term histologic effects (inflammation and granulation tissue) of CVCES on the surrounding tissue?

Methods: Twenty adult male Long-Evans rats with surgically placed shoulder titanium implants were infected with a clinical strain of MRSA (NRS70).

Corrosion and mechanical performance of AZ91 exposed to simulated inflammatory conditions.

Magnesium (Mg) and its alloys, including Mg-9%Al-1%Zn (AZ91), are biodegradable metals with potential use as temporary orthopedic implants. Invasive orthopedic procedures can provoke an inflammatory response that produces hydrogen peroxide (H2O2) and an acidic environment near the implant. This study assessed the influence of inflammation on both the corrosion and mechanical properties of AZ91.

Cathodic Electrical Stimulation Combined With Vancomycin Enhances Treatment of Methicillin-resistant Staphylococcus aureus Implant-associated Infections.

Background: Effective treatments for implant-associated infections are often lacking. Cathodic voltage-controlled electrical stimulation has shown potential as a treatment of implant-associated infections of methicillin-resistant Staphylococcus aureus (MRSA).

Questions/purposes: The primary purpose of this study was to (1) determine if cathodic voltage-controlled electrical stimulation combined with vancomycin therapy is more effective at reducing the MRSA bacterial burden on the implant, bone, and synovial fluid in comparison to either treatment alone or no treatment controls.

Influence of MC3T3-E1 preosteoblast culture on the corrosion of a T6-treated AZ91 alloy.

This study investigated the corrosion of artificially aged T6 heat-treated Mg-9%Al-1%Zn (AZ91) for biomedical applications. Corrosion tests and surface analysis were completed both with and without a monolayer of mouse preosteoblast MC3T3-E1 cells cultured on the sample. Electrochemical impedance spectroscopy (EIS) and inductively coupled plasma mass spectroscopy (ICPMS) were used to explore the corrosion processes after either 3 or 21 days of AZ91 incubation in cell culture medium (CCM).

Cathodic voltage-controlled electrical stimulation of titanium implants as treatment for methicillin-resistant Staphylococcus aureus periprosthetic infections.

Effective treatment options are often limited for implant-associated orthopedic infections. In this study we evaluated the antimicrobial effects of applying cathodic voltage-controlled electrical stimulation (CVCES) of -1.8 V (vs.

Effects of medial meniscal posterior horn avulsion and repair on meniscal displacement.

Medial meniscal posterior root avulsion (MMRA) leads to deleterious alteration of medial joint compartment loading profiles and increased risk of medial degenerative changes. Surgical repair restores more normal biomechanics to the knee. Our hypothesis is that MMRA will cause medial meniscal (MM) extrusion and gap formation between the root attachment site and MM.

The effect of scanning electrochemical potential on the short-term impedance of commercially pure titanium in simulated biological conditions.

The electrochemical history (voltage-time variations) of titanium oxide-solution interfaces can vary widely in vivo, particularly where oxide abrasion is present, and it is important to assess the effects of voltage on the impedance behavior of the interface. Potential step impedance analysis (PSIA) utilizes a time and frequency domain methodology to assess the electrochemical impedance of electrified interfaces over a range of voltages. The PSIA method was used to study the combined effects of scanning electrical potential and the presence of solution-born organic species (protein, amino acids, etc.

The effect of static applied potential on the 24-hour impedance behavior of commercially pure titanium in simulated biological conditions.

Potential step impedance analysis was utilized to evaluate the electrochemical impedance of commercially pure titanium (cpTi) samples that were polarized to static potentials (range from -1000 mV to +1000 mV vs. Ag/AgCl) and immersed in physiologically relevant electrolytes [phosphate buffered saline (PBS) and cell culture medium with 10% fetal bovine serum (AMEM + FBS)] for 24 hrs. The cpTi impedance outcomes were a complex function of voltage, solution constituents, and immersion time.

Titanium is not "the most biocompatible metal" under cathodic potential: The relationship between voltage and MC3T3 preosteoblast behavior on electrically polarized cpTi surfaces.

An electrochemically controlled system has been developed which allows for cell culture directly on electrically polarized metal surfaces with simultaneous control and assessment of the electrochemical current, potential, and impedance of the interface. This system was utilized in this study to assess the interactions between electrochemically polarized commercially pure titanium (cpTi) and MC3T3 preosteoblast cells. Cells were cultured on CpTi for 24 h at static potentials between -1000 mV and +1000 mV vs.

A time-based potential step analysis of electrochemical impedance incorporating a constant phase element: a study of commercially pure titanium in phosphate buffered saline.

The measurement of electrochemical impedance is a valuable tool to assess the electrochemical environment that exists at the surface of metallic biomaterials. This article describes the development and validation of a new technique, potential step impedance analysis (PSIA), to assess the electrochemical impedance of materials whose interface with solution can be modeled as a simplified Randles circuit that is modified with a constant phase element. PSIA is based upon applying a step change in voltage to a working electrode and analyzing the subsequent current transient response in a combined time and frequency domain technique.

Influence of suture material on the biomechanical behavior of suture-tendon specimens: a controlled study in bovine rotator cuff.

Background: Despite technical advances in rotator cuff surgery, recurrent or persistent defects in the repaired tendon continue to occur. Improved strength of sutures and suture anchors has resulted in the most common site of failure being the suture-tendon interface.

Hypothesis: The type of suture material used has a significant effect on the biomechanics of the suture-tendon interface.

Is it safe to perform aggressive rehabilitation after distal biceps tendon repair using the modified 2-incision approach? A biomechanical study.

Background: Despite improved methods of fixation, there is still a delay in early active motion after distal biceps repair.

Hypothesis: Distal biceps repairs using the modified 2-incision technique can be treated with early motion, and there is no difference in the cyclic performance of Ethibond and Fiberwire when used for the repair.

Study Design: Controlled laboratory study.