The present study was designed to yield results that would be used to contribute to the ongoing debate about the mechanism of the in vitro elution of an antibiotic from an antibiotic-loaded acrylic bone cement. To this end, the elution rates (R) of gentamicin sulfate (expressed as a weight percentage of the initial mass of the antibiotic in the specimen, normalized with respect to the duration of the test) from statically loaded (STATIC) and dynamically loaded (+/-10 MPa; 2 Hz; until fracture; DYNAMIC) specimens fabricated from a commercially available acrylic bone cement (VersaBond AB), in phosphate-buffered saline solution at 37 degrees C, were obtained with the use of a spectrophotometric method. There was evidence of microcracking in the fracture surfaces of DYNAMIC specimens, but no such evidence in the case of STATIC specimens. The surface area of the DYNAMIC specimens, during the tensile phase of the cyclical loading, was estimated to be about 3% larger than for the STATIC specimens (1742 mm(2) versus 1696 mm(2)). The bulk porosities P of the specimens in both sets were also determined and found to not be statistically different, with P for the STATIC and DYNAMIC specimens being 8.55 +/- 0.10 and 8.88 +/- 0.18%, respectively. At the end of the test period, R was found to be 0.36 +/- 0.20 and 1.28 +/- 0.14 wt %/day for the STATIC and DYNAMIC specimens, respectively. It is suggested that the present results provide support for the postulate that the elution mechanism of gentamicin in this cement is a surface phenomenon.
"It is therefore interesting to see potentially therapeutic levels of gentamicin at an average of 99 days post insertion of the spacer suggesting that good antibiotic levels are maintained around the spacer for most of the time it is in position. In vitro studies have shown dynamically loaded spacers elute more gentamicin than statically or unloaded spacers . Continued release may be due to shear forces as well as cyclical loading of the implant. "
[Show abstract][Hide abstract] ABSTRACT: Previous in vitro studies have found high levels of antibiotic release in the days immediately following implantation of antibiotic loaded articulating spacers. However there are relatively few data describing the elution profile beyond this immediate period. This study was designed to measure if gentamicin levels continue to be clinically therapeutic after an extended period following in vivo implantation. Twelve patients received a gentamicin loaded articulating spacer between a 1st and 2nd stage revision total knee arthroplasty. At the 2nd stage procedure synovial fluid and blood samples were collected and assayed for the presence of gentamicin. The second stage revision occurred at a median of 99 days following spacer insertion. The median intra-articular gentamicin levels were 0.46 mg/L (0.24 to 2.36 mg/L) which would be considered therapeutic. There were no cases of reinfection. In this study, preformed articulating spacers containing gentamicin provided therapeutic concentrations in the synovial fluid surrounding the joint throughout the period of implantation. These data confirm the observations from in vitro studies, where a prolonged elution profile was observed for such spacers.
The Knee 10/2008; 16(1):39-41. DOI:10.1016/j.knee.2008.07.009 · 1.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Septic arthritis and osteomyelitis is a serious complication of septicemia in foals. Within a given joint, the disease can involve the synovial membrane, the epiphysis, the physis, the metaphysis, and/or the small cuboidal bones of the tarsus or carpus. Early identification and early institution of an aggressive therapeutic protocol can result in a successful outcome. Concurrent systemic illness, type of septic arthritis, multiple joint involvement, pathogenicity of the organism, presence of osteomyelitis, and expected use of the foal are factors that can help formulate a prognosis.
Clinical Techniques in Equine Practice 12/2006; 5(4):309-317. DOI:10.1053/j.ctep.2006.09.005
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