Early administration of hyperbaric oxygen therapy in distraction osteogenesis--a quantitative study in New Zealand rabbits.

BACKGROUND: We investigated the effect of hyperbaric oxygen (HBO) therapy on the early phase of tibial lengthening in our established rabbit model. METHODS: Twenty-four male rabbits (six per group) underwent right tibial lengthening by 5 mm. Group 1 then underwent 2.5 atmospheres of absolute hyperbaric oxygenation for 2 hours daily for 6 weeks postoperatively; group 2, for early 5 weeks (weeks 1-5), group 3, for late 5 weeks (weeks 2-6), and group 4 had no HBO therapy. Bone mineral density (BMD) was measured before surgery and weekly thereafter from weeks 2 through 6. The mechanical strengths of the lengthened tibias were measured. RESULTS: Significantly higher mean %BMDs were obtained for groups 1 and 2 compared with groups 3 and 4. There was no difference in the mean %BMD between groups 1 and 2 (p > 0.05). The results were similar for mean percentage maximal torque; group 1 had the maximum torque, followed sequentially by groups 2 though 4. CONCLUSION: The study results suggest that early and full-term administration of HBO therapy on tibial lengthening may achieve better benefits.

A novel solvent-free method for the manufacture of biodegradable antibiotic-capsules for a long-term drug release using compression sintering and ultrasonic welding techniques.

This report was to develop a novel solvent-free method for the manufacture of biodegradable capsules for a long-term drug delivery. To manufacture an antibiotic capsule, polylactide-polyglycolide copolymers were pre-mixed with vancomycin. The mixture was then injection compression molded to form a cylinder with a cover of 8mm in diameter. After the addition of gentamicin sulfate into the core, an ultrasonic welder was used to seal the capsule. An elution method and an high-performance liquid chromatography assay were employed to characterize the in vitro release rates of the antibiotics over a 30-day period. It was found that biodegradable capsules released high concentration of vancomycin and gentamicin (well above the minimum inhibition concentration) in vitro for the period of time needed to treat bone infection; i.e., 2-4 weeks. A bacterial inhibition test was carried out to determine the relative activity of the released antibiotics. The diameter of the sample inhibition zone ranged from 3 to 18 mm, which is equivalent to 16.7-100% of relative activity. By adopting this novel technique, we will be able to manufacture biodegradable capsules of various medicines for long-term drug delivery.

In vivo release of vancomycin from biodegradable beads.

The current delivery system of antibiotics for the treatment of osteomyelitis uses polymethylmethacrylate (PMMA) beads as a local drug-release agent. The nonbiodegradable nature of the PMMA, however, necessitates a second operation to remove the beads. This article explores the alternative of using biodegradable polymers as antibiotic beads for a long-term drug release in vivo. To manufacture an antibiotic bead, lactide-glycolide copolymers were mixed with vancomycin. The mixture was compressed and sintered at 55 degrees C to form beads 8 mm in diameter. An in vivo animal model was proposed to characterize the elution rate of antibiotic over a 55-day period. Biodegradable beads released high concentrations of antibiotic (well above the breakpoint sensitivity concentration) in vivo for the period of time needed to treat bone infection; that is, 4-6 weeks. A bacterial inhibition test was also carried out to determine the relative activity of the released antibiotics. The diameter of the sample inhibition zone ranged from 8 to 18 mm, which is equivalent to 9.1 to 100% of relative activity. In addition, the antibiotic concentration of systemic blood was found to be very low. Antibiotic-impregnated biodegradable beads may have a potential role in the prevention and management of surgical infections.