[Decolonization for Staphylococcus aureus carriers in arthroplasty surgery after hip fracture]

OBJECTIVE

Staphylococcus aureus is the main causative agent of joint prosthesis infections. The decolonization of the carriers is effective in the prevention of the infections of the elective arthroplasties. The aim of this study is to evaluate if it is also in arthroplasties after hip fracture.

METHODS

Study in patients with hip fracture who underwent joint prosthesis from January 2011 to December 2015 with a protocol of S. aureus detection-decolonization with intranasal mupirocin and chlorhexidine baths. Patients between January 2009 and December 2010 were the comparison group.

RESULTS

In the intervention period, the study of colonization of S. aureus was performed in 307 patients, of whom 87 were positive (28.3%). The study period was completed by 267 patients, of whom two developed S. aureus infection, compared to six of 138 in the control group (0.7% vs 4.3%, RR 0.1, p = 0.03).

CONCLUSIONS

In our study, S. aureus decolonization in patients with hip fracture decreased the incidence of joint prosthesis infection by this microorganism.

[Prosthetic joint infection in patients with hip fracture. Differences from infection of elective prosthesis]

OBJECTIVE

Most publications about prosthetic joint infections (PJI) are referred to elective prosthesis and they exclude arthroplasties due to hip fracture.

METHODS

We conducted a descriptive study about prosthetic joint infections after joint fracture in Alcalá de Henares Hospital (Madrid) between 2009 and 2014 and we compared with elective prosthetic infections in the same period.

RESULTS

There were 30 PJI after hip fracture and 14 elective PJI. The incidence of infection was 4.7% in arthroplasties due to hip fracture from 1.3% in elective prosthesis (RR 3.8, p=0.005). The PJI after fracture affected older patients (82.5 years vs 71.5, p=0.006), with greater comorbidity (5.4 vs 3.6, p=0.003), higher anesthetic risk (ASA>2 70% vs 21.4%, p=0.004) and higher incidence of dementia (50% vs 0%, p=0.02). Staphylococcus aureus was the most common causative agent in both groups, but there was higher incidence of Gram negative-cases in PJI after fracture group (43.3% vs 21.4%, p no significance) and cefazolin-resistance (63.3% vs 28.6%, p=0.03). In logistic regression analysis the treatment had less chance of success in PJI after fracture than elective PJI (33.3% vs 78.6%, OR 0.09, p=0.06).

CONCLUSIONS

The PJI after fracture are more frequent than elective PJI, affect older patients, with poor general condition, are produced by more resistant bacteria and have worst evolution than EPJI.

Hydrophilic polymers derived from vitamin E

Vitamin E containing copolymers for biomedical applications was obtained by copolymerization reaction of vitamin E methacrylate (VEMA) with 2-hydroxyethyl methacrylate (HEMA), N,N-dimethyl acrylamide (DMA) or vinyl pyrrolidone (VP), in different experiments. High molecular weight copolymers prepared by free radical reactions initiated by azobisisobutironitrilo, AIBN, present a random distribution of vitamin E derivatives along the macromolecular chains, and the average composition depends on the initial composition of the reaction medium. The relative flexibility of the polymeric systems was analyzed measuring the glass transition temperature of copolymeric sequences and that of the pure alternating diad (Tg12) obtained by the application of the treatments proposed by Johnston and Barton to all the systems. Tg12 was higher than the average T of both homopolymers (Tg) for the VEMA-HEMA system, Tg12 was lower than Tg for the VEMA-DMA system and Tg12 was similar to Tg for the VEMA-VP system. VEMA-HEMA copolymers gave rise to hydrogels in water, acidic and alkaline media. VEMA-DMA copolymers gave rise to hydrogels in acidic medium and dissolved in water and alkaline medium. VEMA-VP copolymers were soluble in all media. The swelling of all the hydrogels fit a second order kinetics. A VEMA-HEMA hydrogel was selected for in vivo experiments in order to study the influence of vitamin E on the regeneration process of Achilles tendon. The polymeric derivatives of vitamin E stimulated the regenerative process as a consequence of the antiaging effect in the local area of application.

Hydrophilic polymers derived from vitamin E

Vitamin E containing copolymers for biomedical applications were obtained by copolymerization reaction of vitamin E methacrylate (VEMA) with 2-hydroxyethyl methacrylate (HEMA), N,N-dimethyl acrylamide (DMA) or vinyl pyrrolidone (VP), in different experiments. High molecular weight copolymers prepared by free radical reactions initiated by azobisisobutironitrilo, AIBN, present a random distribution of vitamin E derivatives along the macromolecular chains, and the average composition depends on the initial composition of the reaction medium. The relative flexibility of the polymeric systems was analyzed measuring the glass transition temperature of copolymeric sequences and that of the pure alternating diad (Tg12) obtained by the application of the treatments proposed by Johnston and Barton to all the systems. Tg12 was higher than the average Tg of both homopolymers (Tg) for the VEMA-HEMA system, Tg12 was lower than Tg for the VEMA-DMA system and Tg12 was similar to Tg for the VEMA-VP system. VEMA-HEMA copolymers gave rise to hydrogels in water, acidic and alkaline media. VEMA-DMA copolymers gave rise to hydrogels in acidic medium and dissolved in water and alkaline medium. VEMA-VP copolymers were soluble in all media. The swelling of all the hydrogels fit a second-order kinetics. A VEMA-HEMA hydrogel was selected for in vivo experiments in order to study the influence of vitamin E on the regeneration process of Achilles tendon. The polymeric derivatives of vitamin E stimulated the regenerative process as a consequence of the antiaging effect in the local area of application.

Resorbable polyacrylic hydrogels derived from vitamin E and their application in the healing of tendons

A hydrogel containing vitamin E (alpha-tocopherol) was prepared by free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) and alpha-tocopheryl methacrylate (VEMA), the latter being synthesized previously to its use. The hydrogel containing 20 wt % of VEMA showed equilibrium water content in the range of those of hydrogel networks, at any pH. The swelling of the hydrogel followed Fick's law, indicating that sorption of water molecules is controlled by diffusion, although the values of diffusion coefficients for the VEMA-containing hydrogel were lower than those of poly-HEMA in any medium. Surface characterization of the VEMA-containing hydrogel revealed a decrease in the surface energy of solid owing to a decrease of the polar component mainly. The application of finely powdered xerogel of HEMA-VEMA copolymer bearing 20 wt % of the vitamin E derivative gave a very fast and positive response showing an activated regeneration capacity, probably due to the stimulation of the cellular proliferation or the more plausible effect, the cellular protection associated to the antioxidant properties of the vitamin E residue.