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Follow up of biocompatibity of new total hip joint endoprosthesis in a canine model

Rehak L'., Zitnansky M., Soltes I., Horecky J.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 43, nr 1

260-263

EN

Purpose: of this paper was the follow up of biologic compatibility and functional use of new type endoprosthesis in a canine model. Design/methodology/approach: Prospective animal study with evaluation of new type ZRM of titanium alloy cementless total hip replacement (THR) in dogs in 2007. We used congruent ceramic head and polyethylene acetabular inlay. That is the gold standard in THR. The methods of X ray imaging evaluation after implantation and overgrowth evaluation were employed. We evaluated loading and use of the leg during walking and running. Total hip joint replacements were implanted in 6 dogs – German Shepards under general anesthesia. The follow up time was 6 months. We compared X ray findings after the operation and after 6 months, wound healing, use of THR during leg loading and biocompatibility of THR in femur and pelvis. Findings: The femoral and acetabular components were anchored using a press-fit technique. We found good biocompatibility in 5 dogs with good loading during walking and running, one complication with femoral fracture and wound abscess. At six months, there was good bony ongrowth of the THR in 5 dogs and small overgrowth on the surface of THR in one dog, deemed as complication. In the same animal, explanation of the THR was performed, due to fracture. Research limitations/implications: This study was not monitored. In the future, we would like to perform a randomized study design with a control group. Practical implications: The new THR developed by authors can restore function in canine model of damaged hip joint. The press fit anchorage of the cup allowed firm adhesion of the cup surface to the pelvic bone and likewise, the femoral component demonstrated firm fixation in the proximal femur. Originality/value: This paper is original by presenting the first results of new THR in canine model. The value of this paper is in laying groundwork for human study in the future.

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Plasma furnace for smelting and casting metal up to 3000 K

Zitnansky M., Demian S., Caplovic L., Rehak L., Dorschfeld R.

Archives of Materials Science and Engineering

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2010

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Vol. 44, nr 2

112-119

EN

Purpose: The aim of our investigation was a development of plasma furnace for preparing castings of titanium alloy Ti64 ELI by remolding in laboratory at our research workplace. The reason of this paper writing was publishing of innovative information to the technical society. Design/methodology/approach: The objectives were achieved by solution of much research and development works in the very long time interval. The main methods used for our research was study of physic-chemical interaction between a liquid metal and surrounding atmosphere. The approach to the topic of our research was the elimination of interactions between the C, O, N and H and Ti, Al, V, Y, Zr in liquid metal. Contemporary we have solved also the acute ceramic mould for casting of perfect castings from metal of very high affinity to C, O, N and H. The main subject scope of the paper is assignee of very clean materials and much application from that. We are oriented particularly on the preparing parts of cementless total hip joint replacement (THR) and instruments for implantation. Findings: We have created the new original design of the plasma furnace for smelting and castings of high reaction of metal up to 3000 K. temperature. The main conclusion of our result was a practical using for research on very high level and for production of metal and castings from special metal in the final shape. Practical implications: It has been found that the quality of castings from Ti and Nb alloys is very good. The quality of casting was tested by metallographic analysis and by notch specimens. We have been finding out that the mass of casting can be approximately 1.00 kg. This is true statement in the first approximation if the new plasma furnace is arranged as smelting - cleaning - casting system. If the new plasma furnace is arranged as continual smelting system, than we can obtain ingot with the mass two or more kilograms. Originality/value: The design of new plasma furnace is original and also the castings from Ti, Ta and Nb alloys are in our laboratory original resultants and the metallographic analysis as well. In the case, when the castings with a good biocompatibility plays important role, this new plasma furnace can be very useful for preparing implants for body skeleton and spatial casting of material of very high affinity to elements as C, O, H, and N.

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Evaluation of the compatibility of ceramic ball head and femoral stem taper on the new type THR

Rehak L., Zitnansky M.

Archives of Materials Science and Engineering

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2010

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Vol. 44, nr 1

58-61

EN

Purpose: of this paper was follow up of compatibility of femoral component taper from TiAl6V4 ELI acc.ISO5832-3 and ceramic head of the new type of total hip join replacement THR - ZRM in vitro. Design/methodology/approach: from december 2006 to august 2007 we have tested THR taper component and ball ceramic head. On the base of our patents ( SK, CZ, EU, USA) from 1999 to 2006 we have designed and developed the new type of cementlesss THR - ZRM. These total hip replacements were tested in our prospective study. We have evaluated compatibility and loading resistance of taper of THR ZRM made from TiAl6V4alloy ELI and ceramic ball head Biolox forte (28-12/14L) by tests of burst strength, pull out, rotational stability, fatigue and post-fatigue. Tests were monitored independent observer. Findings: in the burst test were tested 7 parts and average loading was 54 kN. The reached values comply with the requirements according to CeramTec procedure VA 02 04 4129 and the FDA Guidance document for the preparation of premarket notifications for ceramic ball hip systems. In the fatigue test all specimens test at a maximum load of 14 kN reached 10 million cycles without mechanical failure. The post fatigue test was performed with load of 46 kN and no failure of head and taper system was observed. The pull-off tests were made with pull out strength of 1439 N has been used on 5 parts and no pullout of ceramic ball head of taper femoral component was observed. Last was the test of rotational stability, where ball head was rotational stable under strength of 1254 Ncm. Research limitations/implications: this study was performed on the small group of spices but enough relevant according FDA and international ISO prescriptions. Originality/value: this study is original by publishing first results of the new cementless THR- ZRM tests of compatibility and fatigue of metal taper and ceramic ball head. Value of this paper is in vitro testing and prepares ZRM cementless THR for clinical use in human.