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Biomedical subjects

W Rostoker

Publications and source records attributed to W Rostoker.

At least 37 records · Page 2Linked to original sources
PubMed1977

Metal carcinogenesis: a study of the carcinogenic activity of solid metal alloys in rats.

The carcinogenic activity of seven metallic alloys was studied by implanting solid rods of each alloy in the gluteal muscles of Sprague-Dawley rats which were killed after twenty-four months. When the number of tumors in these rats was compared with the numbers in rats not operated on, in rats which had a sham operation, and in rats implanted with Silastic rods, no statistically significant differences in the incidences of the tumors in the several groups were found.

Alloys↗
PubMed1976

Biocompatibility of materials for total joint replacement.

The clinical use of total joint prostheses demands absolute biocompatibility of the materials employed. The purpose of this experiment was the bioassay of some materials considered as possible candidates for use in total joint prostheses as load-bearing members or as wear-resistant surfaces. Some materials already in use were also tested. 316L stainless steel was used as a control. The materials were implanted as a standardized rod and in particulate form. An average of 12 samples per material were implanted in soft tissue for six months and a total of 145 rabbits were used in this study. Twenty-five materials including metals, polymers, and ceramics were tested in solid and powdered form. A semiquantitative evaluation of local tissue reaction and a study of organs was performed. Polymers and metallic materials showed in general a mild tissue reaction. Ceramics, which some authors describe as the best tolerated materials, elicited variable tissue responses. Some of these (glass-ceramics) presented very poor tissue tolerance. The least reactive, titanium oxide, titanium aluminate, and aluminum oxide, presented a degree of tissue reaction comparable to that of corrosion resistant metals, but not superior to them. Moderate reactivity was the general rule for particulate materials except for the Pyroceram glass-ceramics, polymides, and Teflon. Ultrahigh molecular weight polyethylene in particulate form elicited a rather cellular tissue response, a fact to be considered when projecting long-term results in total joint arthroplasty. No pathological changes compatible with systemic toxicity by materials tested were observed in the study of the organs.

Animals↗
PubMed1976

Some new studies of the wear behavior of ultrahigh molecular weight polyethylene.

The wear rate of ultrahigh molecular weight (UHMW) polyethylene over a long campaign of sliding distance is not constant. Both unfilled and graphite filled polyethylene show a high rate early, which reduces to a low value. The graphite-filled product shows a late stage increase in wear rate. Increased molding temperature reduces the molecular weight and increases the wear rate. Titanium articulating with UHMW polyethylene develops frequently an abnormally high wear rate with the generation of a black wear product.

Biocompatible Materials↗
PubMed1976

A statistical treatment of fatigue of the cast Co-Cr-Mo prosthesis alloy.

Fatigue tests have been conducted on commercially produced cast Co-Cr-Mo alloy in tension-tension while surrounded by a physiological solution at 37 degrees C. The data have been analyzed by statistical techniques to yield an allowable stress such that there is 95% confidence of less than one failure in 1,000 after 5 X 10(7) cycles of stress fluctuation. These results are valid for a substantially sounder material than may be common in commercial use and therefore a more conservative allowable stress probably ought to be used for design purposes.

Alloys↗
PubMed1975

MP35N: a corrosion resistant, high strength alloy for orthopedic surgical impants: bio-assay results.

A cobalt based alloy, MP35N, with excellent mechanical properties has been recently introduced as a material for surgical orthopedic implants. A study was made of local and systemic host response to this material in two different mammal species. The implantation time ranged from one to 12 months. The result of this study indicated: MP35N produces a degree of local tissue response comparable to that of 316L stainless steel. No systemic side effects were observed during the implantation times included in this study.

Alloys↗
PubMed1975

Failed femoral stems in total hip prostheses. A report of six cases.

Six femoral stems of total joint prostheses failed and were studied. These included two short-neck Müller, one standard Müller, one new design long-neck Müller, and two Charnley prostheses. In addition, reference is made to another failed Charnley prosthesis which had not required revision at the time of the study. Reoperation and replacement of the femoral component was required in all six cases. Metal fatigue appeared to be the cause of failure in all instances. Metallographic examination of the removed prosthesis revealed no underlying defects in one prosthesis. In the other five prostheses metallurgical defects were found. Varus placement of the femoral prosthesis or loosening of the cement-prosthesis bond, or both, were identified in five of the six and were thought to have led to overload. A combination of metal defects and loosening or malpositioning was thought to be responsible for the failures. It was further indicated that current designs should be regarded as marginal in relation to long service life, until more fatigue information is available on the metallic materials currently in use.

Aged↗