Implant stability in the treatment of MRSA bone implant infections with linezolid versus vancomycin in a rabbit model.

The increasing prevalence of methicillin-resistant Staphylococcus aureus (MRSA) infections represents a significant healthcare burden. Vancomycin and linezolid exhibit potent clinical and microbiological activity in MRSA infections. Our purpose was to investigate the efficacy of linezolid versus vancomycin in experimental implant infections and the influence on implant stability in a rabbit model. Thirty-six female New Zealand White rabbits received surgical insertion of titanium implants into their distal femurs and were randomly assigned to six groups (A: infected, no treatment; B: infected, vancomycin; C: infected, linezolid; D: no infection, no treatment; E/F: no infection, vancomycin or linezolid, respectively). Antibiotics were administered, and plasma levels determined. Bone-implant specimens were tested for mechanical stability of fixation. Quantitative histomorphometry of bone and soft tissue was performed using computerized image analysis. Plasma levels of linezolid and vancomycin were within the respective therapeutic ranges. Microbiological analysis of specimens from infected rabbits showed MRSA tissue colonization in all untreated animals, in two of six vancomycin-treated animals, and in none of the linezolid-treated animals. Antibiotic treatment improved mechanical stability significantly (p = 0.004) with both vancomycin and linezolid. Mechanical testing correlated with histomorphometry results. A significant negative correlation was found between displacement of the implant and the percentage of calcified tissue around the implant, and a significant positive correlation was found between displacement of the implant and the amount of noncalcified tissue. Our data indicate that both treatment regimens improved implant stability.

Long-term results of hip arthroplasty in ambulatory patients with cerebral palsy.

Osteoarthritis (OA) secondary to dislocation and dysplasia is a common problem in patients with cerebral palsy. The purpose of this study was to evaluate the results of total hip replacement (THR) in ambulatory patients with cerebral palsy. Eighteen total hip arthroplasties were performed in 16 ambulatory patients with cerebral palsy. The patient's mean age at surgery was 42 +/- 8 years (range 32-58 years), and the mean follow-up was 10 +/- 6 years (range 2-18 years). Data were obtained by a standardised telephone interview. There was a significant postoperative reduction in pain on the NAS (narrative analogue scale) from 8.4 preoperatively to 1.1 postoperatively (p = 0.002). At follow-up no stem had been revised. Three cups were revised for aseptic loosening at two and six years, and one cup was revised for recurrent dislocation of the hip. One hip was revised for infection 12 years after the index surgery. One hip dislocated (three months postoperatively) and was treated by closed reduction. In ambulatory patients with cerebral palsy and secondary osteoarthritis of the hip THR can provide long-term pain relief and improved function. The rate of long term complications was moderate in this series; however, the dislocation rate was higher than in standard OA cases.

Optical switch based on a fluid-filled photonic crystal fiber Bragg grating.

We report the implementation of an in-fiber optical switch by means of filling a fluid into the air holes of a photonic crystal fiber with a fiber Bragg grating. Such a switch can turn on/off light transmission with an extinction ratio of up to 33 dB within a narrow wavelength range (Bragg wavelength) via a small temperature adjustment of +/-5 degrees C. The switching function is based on the temperature-dependent coupling between the fundamental core mode and the rod modes in the fluid-filled holes resulting from the thermo-optic effect of the filled fluid.