Orthopedic Device-Related Infections (ODRIs) are a major medical challenge, particularly due to the involvement of biofilm-encased and multidrug-resistant bacteria. Current treatments, based on antibiotic administration, have proven to be ineffective. Consequently, there is a need for antibiotic-free alternatives. Antimicrobial peptides (AMPs) are a promising solution due to their broad-spectrum of activity, high efficacy at very low concentrations, and low propensity to induce resistance. We aim to develop a new AMP-based chitosan nanogel to be injected during orthopedic device implantation to prevent ODRIs. Chitosan was functionalized with norbornenes (NorChit) through the reaction with carbic anhydride and then, a cysteine-modified AMP, Dhvar5, a peptide with potent antibacterial activity, even against methicillin-resistant Staphylococcus aureus (MRSA), was covalently conjugated to NorChit (NorChit- Dhvar5), through a thiol-norbornene photoclick chemistry (UV= 365 nm). For NorChit-Dhvar5 nanogels production, the NorChit-Dhvar5 solution (0.15% w/v) and Milli-Q water were injected separately into microfluidic system. The nanogels were characterized regarding size, concentration, and shape, using Transmission Electron Microscopy (TEM), Nanoparticle Tracking Analysis (NTA) and Dynamic light scattering (DLS). The nanogels antibacterial properties were assessed in Phosphate Buffer (PBS) for 6 h, against four relevant microorganisms (Pseudomonas aeruginosa, S. aureus and MRSA, and in Muller- Hinton Broth (MHB), 50% (v/v) in PBS, supplemented with human plasma (1% (v/v)), for 6 and 24 h against MRSA. The obtained NorChit-Dhvar5 nanogels, presented a round-shaped and ∼100 nm. NorChit- Dhvar5 nanogels in a concentration of 10¹⁰ nanogels/mL in PBS were capable of reducing the initial inoculum of P. aeruginosa by 99%, S. aureus by 99%, and MRSA by 90%. These results were corroborated by a 99% MRSA reduction, after 24 h in medium. Furthermore, NorChit-Dhvar5 nanogels do not demonstrate signs of cytotoxicity against MC3T3-E1 cells (a pre-osteoblast cell line) after 14 days, having high potential to prevent antibiotic-resistant infection in the context of ODRIs.

The purpose of this study was to evaluate the subjective and objective functional outcome after osteosynthesis of the forearm bone fractures with plates and screws (ORIF) or elastic nailing (CRIF).

We evaluated 55 patients (45 men and 10 women) who underwent internal fixation of both forearm bones with CRIF or ORIF, concerning the range of motion of the forearm, wrist and elbow (pronation, supination, flexion and extension), grip strength and a validated outcome measure (DASH score). The mean duration of follow-up was 3 years, and standardized radiographs of the forearm were evaluated. The mean age was 41.6.

We used the Student's t test to compare means and chi-square test to compare proportions.

The mean (confidence interval 95%) of the DASH scale was 29.6 (22.6 to 36.5), significantly higher (p<0.001) than the normative value in the U.S. (10.1). There was a statistically significant reduction of forearm supination (86.4 vs. 64.6, p<0.001) and grip strength (0.63 vs. 0.48, p<0.001) in relation to the opposite member; grip strength decrease correlated with worse subjective outcome (p<0.02). There were no significant differences between groups undergoing ORIF or CRIF. The risk of nonunion and reintervention was not different between groups (p=0214).

Forearm bones fractures are associated with high rates of consolidation and satisfactory mobility of the forearm since we obtain an anatomic reduction of the fracture, as is most easily achieved by plate fixation. However, elastic nailing is a less invasive technique that allows restoring function more quickly with less pain and no increased risk of complications. Given the scant scientific evidence currently available we will require a more comprehensive study to compare the anatomical and functional outcome after ORIF and CRIF.