Structure optimization of TiNi orthopaedic implants

Vol. 5, C8 (1995): International Conference on Martensitic Transformations : ICOMAT 95, Lausanne, Switzerland, August 20-25, 1995The optimized structure of TiNi ''memory implants'' results from optimized mechanical and heat treatment. The key characteristics (extent of recovery strain, generated forces, transformation temperatures) are dependent on the state of a TiNi alloy structure and on the stiffness of the system to be tired It follows from TEM analysis that the most important strustural parameters are the grain size of B2 phase and the dislocation density. Both these factors modify the conditions of B19' formation

Titanium-nickel shape memory clamps in small bone surgery

The therapeutic applications of titanium-nickel (TiNi) shape memory clamps with optimized structural characteristics for fixation of small bone fragments in 64 patients are presented. Our fixative makes compressive stabilization possible and enables a patient to start rehabilitation very soon after surgery. The supporting splint immobilization never exceeded 12 days. Three aspects were studied: bone union, wound healing problems and histology. Non-union occurred in 4 patients treated with only one fixative. Two clamps implanted in non-parallel planes seem to be advisable to exclude the need for longer immobilization. Neither toxic manifestation nor episodes of an allergic reaction occurred. No suppuration appeared when a heat stimulus was supplied by using a contact resistance heater. Histological evaluation of the tissue covering the implants in 22 patients did not reveal any adverse reaction. Our study suggests that by using TiNi clamps in an appropriate way, satisfactory outcomes could be achieved with respect to both biofunctionality and biocompatibility.Web of Science1176-734434

Structure and surface of TiNi human implants

The surface and the "bulk" structure of TiNi implants were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoemission spectroscopy (XPS), and scanning Auger microprobe analysis (AES). TiNi implants were compared with otherwise identically prepared non-implanted specimens, and sputter-cleaned and reoxidized samples. Nonimplanted and implanted samples had essentially the same surface topography and microstructure. Ti, O, and C were the dominant elements detected on the surface. Trace amounts(similar to 1 at%) of Ni and Ca, N, Si, B, and S were also detected. Ti was present as TiO2 on the surface, while nickel was present in metallic form. A significant difference in Ni peak intensity was observed when retrieved or non-implanted control samples (a very low nickel content) were compared with sputter-cleaned and reoxidized samples (well-detected nickel). It is evident that the method of passivation is crucial for nickel loosening. No major changes occurred in the TiNi samples bulk structure or in the surface oxide during the implantation periods investigated

TiAlV/Al2O3/TiNi shape memory alloy smart composite biomaterials for orthopedic surgery

The structure and properties of TiNi/Al2O3/Ti-alloy composite implant materials consisting of a Ti-alloy body and active TiNi shape memory elements is discussed The structure of composites and ceramic/metal interfaces were evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), accompanied with energy and wave dispersive X-ray microanalysis (EDX, WDX). Mechanical testing of composite materials was performed using an Inova tensile/compression test machine. Bone/implant interaction and design parameters are also discussed. The structure of the TiNi alloy is modified in the casting process. Similar effects to those observed in the annealing process occurred in TiNi materials during casting and cooling of composites. The Ti-alloy matrix is composed of a mixture of α and β phases. The interaction between the ceramic layer and the metallic components depends on the cooling rate in the casting process. Different reaction products were identified on the Al2O3/metal interface with dependence on the applied cooling rate of the composite. The fatigue life of the investigated composites is greater than 10(7) cycles, and mechanical properties are sufficient to carry loads expected in human medicine. A newly developed smart implant enables quasielastic fixation with an active role of bone tissue in load carrying process, which has a positive impact on treatment

Vyhodnocení připravenosti České republiky splnit požadavky na kvalitu ovzduší podle směrnic EU a Konvence LRTAP:Zhodnocení a optimalizace stávající staniční sítě a verifikace návrhu sítě ověřovacím měřením

Zpráva je rozdělena do jednotlivých etap: DU01-1.E3 Zhodnocení efektivnosti stávající sítě monitoringu mokré atmosférické depozice. DU01-1.E4 Návrh a zahájení ověřovacích měření v oblastech vymezených v DU02-2, kde je dle směrnice 96/62/EC povinné měření, ale kde měřicí stanice stávající sítě chybí. DU01-1.E5 Návrh optimalizované sítě monitoringu kvality ovzduší. DU01-2.E4+5 Optimalizace některých statistických vlastností měřicí sítě PM10 metodami prostorové statistiky. Analýza kovarianční struktury dat PM10. DU01-3.E4 Návrh systému provozu a obsluhy vzorkovačů PM10 a PM2,5. DU01-3.E5 Zhodnocení monitorování VOCs, POPs a těžkých kovů na stanici EMEP