Methods: A rat model of a critical-sized femoral defect was used. External fixators were constructed to provide different degrees of stiffness and, importantly, the ability to change stiffness during the healing process in vivo. Healing of the critical-sized defects was initiated by the implantation of 11 mu g of recombinant human BMP (rhBMP)-2 on a collagen sponge. Groups of rats receiving BMP-2 were allowed to heal with low, medium, and high-stiffness fixators, as well as under conditions of reverse dynamization, in which the stiffness was changed from low to high at two weeks. Healing was assessed at eight weeks with use of radiographs, histological analysis, XMU-MP-1 microcomputed

tomography, dual x-ray absorptiometry, and mechanical testing.

Results: Under constant stiffness, the low-stiffness fixator produced the best healing after eight weeks. However, reverse dynamization provided considerable improvement, resulting in a marked acceleration of the healing process by all of the criteria of this study. The histological data suggest that this was the result of intramembranous, rather than endochondral, ossification.

Conclusions: Reverse dynamization accelerated healing in the presence of BMP-2 in the rat femur and is worthy of further investigation find more as a means of improving the healing of large segmental bone defects.”
“Co100-xZrx

(40 nm) thin films with different Zr compositions were grown on silicon substrates by radio frequency magnetron Metabolism inhibitor sputtering. The coercivity decreased with an increase in the Zr composition. A uniaxial anisotropy existed in the Co100-xZrx films, and the anisotropy field of the films decreased from 55 to 40 Oe with the increase of Zr composition. The resonance frequency and linewidth were decreased with the increase of the Zr composition during the permeability measurements. For samples with x=0 and 9, the magnetic anisotropy effective field and saturated field were obtained by fitting the external magnetic field dependent resonance frequency with Landau-Lifschitz-Gilbert equation. Therefore, it is an effective way to get the adjustable anisotropy

field and linewidth, which is desirable for obtaining the high resonance and high permeability ferromagnetic film materials for high frequency application. (C) 2009 American Institute of Physics. [doi:10.1063/1.3260238]“
“Background: Propionibacterium acnes has been grown on culture in half of the reported cases of chronic infection associated with shoulder arthroplasty. The presence of this organism can be overlooked because its subtle presentation may not suggest the need for culture or because, in contrast to many orthopaedic infections, multiple tissue samples and weeks of culture incubation are often necessary to recover this organism. Surgical decisions regarding implant revision and antibiotic therapy must be made before the results of intraoperative cultures are known.