PubMed · 8962941
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D Williams. 1996. [editorial].. https://pubmed.ncbi.nlm.nih.gov/8962941/
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The effect of a hydroxyapatite-tricalcium phosphate (HA) material on collagen synthesis by human osteoblasts was investigated using X-ray photoelectron spectroscopy (XPS). To this aim, thin HA slices were exposed to osteoblasts harvested from three different patients, for 20 days and then analyzed by XPS. Platinum plates were also exposed to the cells for comparison, and control tests were performed on both materials using cell-free media. XPS analysis supported by standard spectra of some polyaminoacids and of collagen deposited on HA suggested that a deposition of collagen occurred on the HA slices in the presence of osteoblasts. On the other hand, only an aspecific deposition of proteins was observed on platinum and when cell-free media were used. These data were confirmed evaluating collagen synthesis by [(3)H]proline incorporation of osteoblasts exposed to HA.
The biological response to prosthetic wear particles is thought to stimulate the bone loss that often leads to prosthetic joint failure. This in vitro study investigates how metal particles corrode under physiological conditions and how biological responses to particles may change as particles age. Cobalt chrome alloy (CoCr) and 316L stainless steel (SS) particles of a similar size, shape, and concentration to those found in revision tissues were used. The release of soluble metal (Co and Cr from CoCr particles and Fe from 316L SS) was markedly reduced with time under physiological conditions. CoCr particles released far more Co than Cr. The biological responses to aged and freshly produced particles were tested using human monocytes because wear particles are usually associated with this type of cell in the periarticular tissues. Aged particles of both metals were markedly less toxic to monocytes than freshly produced particles. Aged particles also appeared to stimulate the release of more IL-6 and prostaglandin E(2) from monocytes. The results show that CoCr and 316L SS particles become less toxic but may induce more bone resorbing mediators as they age in vivo.
To standardize industrial implant production and make comparisons between different experimental results, we have to be able to quantify the crystallinity of hydroxyapatite. Methods of measuring crystallinity ratio were developed for various HA samples before and after plasma spraying. The first series of methods uses X-ray diffraction. The advantage of these methods is that X-ray diffraction equipment is used widely in science and industry. In the second series, a neutron diffraction method is developed and the results recorded are similar to those obtained by the modified X-ray diffraction methods. The advantage of neutron diffraction is the ability to obtain measurements deep inside a component. It is a nondestructive method, owing to the very low absorption of neutrons in most materials.