On-demand antibiotic-eluting microchip for implanted spinal screws

Screw Osteointegration-Increasing Biomechanical Resistance to Pull-Out Effect

Spinal disorders cover a broad spectrum of pathologies and are among the most prevalent medical conditions. The management of these health issues was noted to be increasingly based on surgical interventions. Spinal fixation devices are often employed to improve surgery outcomes, increasing spinal stability, restoring structural integrity, and ensuring functionality. However, most of the currently used fixation tools are fabricated from materials with very different mechanical properties to native bone that are prone to pull-out effects or fail over time, requiring revision procedures. Solutions to these problems presently exploited in practice include the optimal selection of screw shape and size, modification of insertion trajectory, and utilization of bone cement to reinforce fixation constructs. Nevertheless, none of these methods are without risks and limitations. An alternative option to increasing biomechanical resistance to the pull-out effect is to tackle bone regenerative capacity and focus on screw osteointegration properties. Osteointegration was reportedly enhanced through various optimization strategies, including use of novel materials, surface modification techniques (e.g., application of coatings and topological optimization), and utilization of composites that allow synergistic effects between constituents. In this context, this paper takes a comprehensive path, starting with a brief presentation of spinal fixation devices, moving further to observations on how the pull-out strength can be enhanced with existing methods, and further focusing on techniques for implant osteointegration improvement.

Solid implantable devices for sustained drug delivery

Implantable drug delivery systems (IDDS) are an attractive alternative to conventional drug administration routes. Oral and injectable drug administration are the most common routes for drug delivery providing peaks of drug concentrations in blood after administration followed by concentration decay after a few hours. Therefore, constant drug administration is required to keep drug levels within the therapeutic window of the drug. Moreover, oral drug delivery presents alternative challenges due to drug degradation within the gastrointestinal tract or first pass metabolism. IDDS can be used to provide sustained drug delivery for prolonged periods of time. The use of this type of systems is especially interesting for the treatment of chronic conditions where patient adherence to conventional treatments can be challenging. These systems are normally used for systemic drug delivery. However, IDDS can be used for localised administration to maximise the amount of drug delivered within the active site while reducing systemic exposure. This review will cover current applications of IDDS focusing on the materials used to prepare this type of systems and the main therapeutic areas of application.

Does the Presence of a Preexisting Open Wound Increase Complication Risk for Implant Procedures?

ABSTRACT

Despite limited evidence, a common belief in surgical practice is that patients should not undergo elective surgery until any open wounds heal because of the risk of seeding infection to the new surgical site. To our knowledge, this is the first study to analyze postoperative complication rates for implants placed in the context of open wounds using the American College of Surgeons National Surgical Quality Improvement Program database. We examined 30-day postoperative infections for breast, hip, knee, and spine implants using the 2012-2016 American College of Surgeons National Surgical Quality Improvement Program database. Patients were excluded for missing data and propensity matched 1:10 for demographics and comorbidities to minimize confounders. Complication rates were assessed using Pearson χ2 tests. Of 475,101 patients who received breast, hip, knee, or spine implants, 1491 did so with an open wound. After propensity score matching, the overall complication rate remained higher with the open wound cohort (6.7% vs 3.8%, P < 0.001). Although the presence of an open wound was associated with an increased risk of superficial surgical site infection, it was not associated with an increased risk of organ space surgical site infection, the site best correlated with infection at the implant. Nor was the presence of an open wound associated with a statistically significantly increased risk of deep incisional surgical site infection or wound dehiscence. After controlling for demographics, preoperative comorbidities, and surgical factors, the presence of an open wound before implant surgery is associated with an increased risk of complications, readmission, and reoperation, but not necessarily infection at the surgical site.

Evolution of drug-eluting biomedical implants for sustained drug delivery

In the field of drug delivery, the most commonly used treatments have traditionally been systemically delivered using oral or intravenous administration. The problems associated with this type of delivery is that the drug concentration is controlled by first pass metabolism, and therefore may not always remain within the therapeutic window. Implantable drug delivery systems (IDDSs) are an excellent alternative to traditional delivery because they offer the ability to precisely control the drug release, deliver drugs locally to the target tissue, and avoid the toxic side effects often experienced with systemic administration. Since the creation of the first FDA-approved IDDS in 1990, there has been a surge in research devoted to fabricating and testing novel IDDS formulations. The versatility of these systems is evident when looking at the various biomedical applications that utilize IDDSs. This review provides an overview of the history of IDDSs, with examples of the different types of IDDS formulations, as well as looking at current and future biomedical applications for such systems. Though there are still obstacles that need to be overcome, ever-emerging new technologies are making the manufacturing of IDDSs a rewarding therapeutic endeavor with potential for further improvements.