Novel coatings for hard tissue implants

A novel deposition process named CoBlastTM, based on grit blasting technology, has been used to deposit hydroxyapatite (HA) onto titanium (Ti) metal using a dopant/abrasive regime. The various powders (HA powder, apatitic abrasives) and the treated substrates were characterised for chemical composition, coating coverage, crystallinity and topography including surface roughness. The surface roughness of the HA surfaces could be altered using apatitic abrasives of different particle sizes. Compared to the standard plasma spraying process, the CoBlast surface produced excellent coating adhesion, lower dissolution, higher levels of mechanical and chemical stability in stimulated body fluid (SBF). Enhanced viability of osteoblastic cells was also observed on the CoBlast HA surfaces compared to the microblast and untreated Ti as well as the plasma HA coating. CoBlast offers an alternative to the traditional methods of coating HA implants with added versatility. Apatites substituted with antimicrobial metals can also be deposited to add functionality to HA coatings without cytotoxicty. The potential use of these coatings as an infection preventing strategy for application on hard tissue implants was assessed in vitro and also in vivo. Surface physicochemical properties and morphology were determined in addition to surface cytocompatibility assessments using a MG-63 osteoblast cell line. The antibacterial potential of the immobilised metal ion on the surface and the eluted ion to a lesser extent, contributed to the anticolonising behaviour of the surfaces against a standard bacteria strain (S. aureus) as well as a number of clinically relevant strains (MRSA, MSSA and S. epidermis). The results revealed that the surfaces coated with silver substituted apatites (AgA) outperformed the other apatites examined (apatites loaded with Zn, Sr and both Ag and Sr ions). Assessment of bacterial adherence on coated K-wires following subcutaneous implantation in a nude mouse infection model (S. aureus) for two days demonstrated that the 12% wt surface outperformed the 5% wt AgA coating. Lower inflammatory responses were activated with the insertion of the Ag loaded K-wires with a localised infection at the implantation site noted over the two day study period. These results indicated that the AgA coating on the surface of orthopaedic implants demonstrate good biocompatibility whilst inhibiting bacterial adhesion and colonising of the implant surface.

Has your work worked you too hard? Physically demanding work and disability in a sample of the older Irish population

There is a heightened need for the practitioner to be alert to the determinants of functional limitations and disabilities owing to the ageing workforce. This study investigated the association between work type and disability in older age in both the paid and the previously unexplored, unpaid worker (household labour).Data on demographic factors, physical measurements, work history and functional status were collected on three hundred and fifty seven 57-80-year-olds. Past or present work was identified as either physically demanding or not. Functional limitations and activities of daily living (ADL) disabilities were assessed using validated scales. Logistic regression was used to examine the relationship between the dependent variables and work type (physically demanding work or not physically demanding work).Over half of the sample reported doing physically demanding work. 20 % had complete function (n = 67), 65 % (n = 223) functional limitations and 15 % (n = 53) ADL disability. Physically demanding work was associated with functional limitations [OR 2.52 (1.41, 4.51), p = 0.01] and ADL disability [OR 2.10 (1.06, 4.17), p = 0.03] after adjustment for a measure of obesity and gender. When gender stratified, looking only at females, physically demanding work was associated with ADL disability [OR 2.79 (1.10, 7.07), p = 0.03] adjusted for a measure of obesity and household labour. Physically demanding work was related to functional limitations and ADL disability in older age. This is valuable information to inform practitioners in the treatment of older people with functional limitations and disabilities and in guiding interventions in the prevention of work related disability.