Implant diameter and bone density: effect on initial stability and pull-out resistance

The New South Wales Department of Corrective Services has introduced a number of suicide prevention measures in order to deal with the problem of inmate suicides. This article describes the measures. The article also shows that the characteristics of the incarcerated population differ greatly from those in the community. Findings from the self-harm database 1991-1995 show that, nevertheless, there are some unique characteristics of the group of self-harmers and fatal self-harmers. These findings are discussed in relation to the preventive measures that are introduced in the NSW correctional centers.     

Exposure of macrophage-like cells to titanium particles does not affect bone resorption, but inhibits bone formation

Endocrine tumours of the pancreas, even in case of liver involvement, are generally characterized by a slower evolution and a better prognosis, if compared with ductal carcinoma. This fact gives reason to a radical surgical approach, whenever possible, and to the research of any effective adjuvant treatment. For this purpose, hepatic transarterial chemoembolization (TACE) has been proposed in recent years for the treatment of metastatic endocrine tumours. Out of 80 patients suffering from endocrine tumours of the pancreas, observed between January 1985 and December 1996, 28 (35%) presented liver metastases at the time of diagnosis. Twelve of these patients were submitted to palliative resection of pancreatic tumour and one or more cycles of TACE. Overall survival was 50% (6/12); median survival was 35.4 months (range 4-75). These results suggest that chemoembolization, combined with surgical resection of primary malignancy, appears to be able to control the disease for a certain time and to increase the survival rate.     

PM compaction equations applied for the modelling of titanium hydride powders compressibility data

ABSTRACT

The suitability of compaction equations commonly used in PM was investigated for the modelling of TiH₂ powder compaction. Compressibility data of TiH₂ powder fractions (<45, <150 and <355?μm) were obtained up to 800?MPa and fitted to the Heckel equation, as well as to the models of Gerdemann and Jablonski and Cooper and Eaton. Although a partial correlation was observed for the Heckel equation, the model provided a consistent approximation of TiH₂ powder yield strength. An accurate fit was observed for the Gerdemann and Jablonski equation; however, considering the brittleness of TiH₂, a more realistic depiction of the physical process was verified from the Cooper and Eaton model. By the addition of an exponential term to the original equation an excellent fit was attained, and compaction of TiH₂ powders could be appropriately described according to the mechanisms of initial density, particle rearrangement, fragmentation and plastic deformation.     

Biologic attachment of an allograft bone and tendon transplant to a titanium prosthesis

An Achilles tendon allograft with its bony insertion was used to bridge a Titanium implant, containing an endoprosthetic tendon anchor, and the sheep biceps muscle. Twelve sheep were operated on unilaterally and followed up clinically and histologically for 2, 4 (n = 2), 8, and 12 months (n = 4). Full function of the front limb was regained after 8 to 12 weeks. There were no signs of mechanical loosening at all times. The morphologic changes at the bone block and implant fixation site were an initial revascularization of the allograft bone, which was observed at 2 months and enhanced at 4 months but occurred without any evidence of bone remodeling. This was changed in all specimens taken at 8 and 12 months where intensive new bone development, remodeling, and bone ingrowth in the titanium implant was found. Bone mass was shifted significantly to the tendon insertion half of the bone block because of a creeping substitution of the cancellous allograft bone and bone ingrowth to the implant. Overall bone mass slightly decreased with time but resorption of allograft bone outweighed new bone development only at lesser loaded areas. Transplantation of a bone and tendon allograft to an implant resulted in a revitalized, mechanically stable, and biologically anchored compound.     

Surface-dimpled commercially pure titanium implant and bone ingrowth

The purpose of this investigation was to examine the effect of the surface macrostructure of a dimpled commercially pure titanium (cp Ti) implant on bone ingrowth in vivo by means of histological examination and a push-out test. Cylindrical implants were inserted in one femur of each experimental rabbit and the animals were killed at 1.5, 3 and 13 months after implantation. The femur with the implant of each animal was then examined in a push-out test. The fracture surfaces of the bone-implant interface after the push-out test were examined under light and electron microscopy. It seems that the dimpled cp Ti surface results in the increased retention of the cp Ti implant in bone due to interlocking between vital bone and the dimples.