The concentration of methylmethacrylate monomer (MMA) in the blood stream after implantation of the components of 15 total hip prostheses using bone cement was determined in the pulmonary artery, the radial artery, and the superior vena cava after cement application, and correlated with the observed drop in blood pressure and the increase in the pulmonary arterial pressure. In all samples MMA was found. The values ranged from 0.02 micrograms/ml to 59 micrograms/ml. The mean maximum value after implantation of the stem was measured to be 7.8 micrograms/ml in the pulmonary artery, 4.6 micrograms/ml in the radial artery, and 1.75 micrograms/ml in the superior vena cava. After implantation of the cup the values were clearly lower. The simultaneously recorded blood pressure decreased slightly during the first 3 min and then returned to previous values. The pulmonary arterial mean pressure increased from 18 to 20 mmHg during the first 10 min. Although in some patients a drop in blood pressure started at the same time as MMA reached maximum values, high concentrations did not result in a greater effect on the circulatory parameters. Statistical analysis by the Spearman test revealed no correlation between MMA concentrations and the decrease in blood pressure or the increase in the pulmonary arterial pressure.

Circulatory and respiratory reactions during the implantation of joint endoprostheses have been observed for years. The components of the bone cements used for anchoring (methyl methacrylate monomer) or the outpour of bone marrow substances from the affected bone marrow cavity are thought to be chiefly responsible for these effects. However, our previous investigations demonstrated unambiguously that reactions of this type can be attributed to direct nervous-reflex mechanisms triggered by the pressure rise in the medullary canal, and that, in addition, bone marrow embolism plays a part in serious circulatory incidents. The investigations on which the present paper is based have confirmed the mechanism of circulatory reactions triggered by direct nervous reflex and have shown once again that the release of cement monomers is not of any significance, at least not in animal experiments. In regard of the characteristics of these reflex processes, it has been possible to show by both surgical and pharmacologic interventions in the vegetative nervous system, performed before and during pressure experiments, that these reflex processes are caused not so much by an increase of the vagus tone as by a central inhibition of the sympathicus. Neither administrations of atropine nor bilateral cervical vagotomy are able to prevent the reactions. This was only possible under the influence of a ganglion blocker.

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The investigations presented in this paper concern the question of toxicity of Bariumsulfate as an ingredient of bone-cement. In 6 rabbits the medullary cavity of the right femur was filled with bone-cement which contained Bariumsulfate as X-ray contrast ingredient and the left one with BaSO4-free bone-cement. 4 1/2 months post operationem the femura were investigated by histological and microradiographic methods. The status of both sides was compared. On the BaSO4-containing side regularly necrotic lamellar bone structures in the zones of osteogenesis and single disseminated necroses are found which are not caused by the primary lesion occuring during the implantation procedure. Additionally the zone of primary lesions which is found on both sides was more extensive at the BaSO4-containing side.

Background: As a result of numerous failed implantations of cemented ankle prostheses since the early 70s, ankle arthrodesis represented the "gold standard" in the treatment of ankle arthrosis. Due to a change to cementless implantations in the 90s it came to a remarkable reduction in early loosening, bone necrosis and sintering of the prosthesis which were the main reasons for former failures. In cooperation with ESKA Implants, Lübeck, we have developed a cementless anatomic ankle prosthesis. Patients and Methods: At our hospital, the ESKA prosthesis has been implanted in 56 patients (72% posttraumatic) since 1990. In our study, we report the examination results of 40 out of these 56 patients at least 1 year post implantation (21 of them more than 5 years). For evaluation, we used the Kofoed ankle score, which allows an easier comparison with other studies. This score showed an average improvement from 34.75 points preoperatively to 91.25 points postoperatively. Results: The persistent preoperative pain had completely disappeared in all patients; only twelve patients complained of intermittent pain under fairly heavy loading. 23 patients were able to walk > 2 km and 13 > 5 km without pain. The overall range of motion was 40-60° in 14 patients, 25-40° in 21, and < 25° in only five. We did not see any kind of secondary arthrosis in the adjacent joints. An arthrodesis which posed no problems had to be performed only three times: in two cases in 1991, during the 1st postoperative year, with both patients showing infections of the prosthesis; in the third case, the prosthesis had to be changed after 9 years.Conclusions: According to our good results and those of other studies on cementless ankle prostheses, we consider a cementless upper ankle prosthesis, implanted by a highly experienced surgeon, the preferable alternative to upper ankle arthrodesis.

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This paper shows the effects of the increase in pressure in the medullary cavity in the blood circulation and the respiration observed during implantation of bone cement with animal experiments. The pathomechanism is also examined. The reactions of the respiration and the circulation, when observed, resulted in the intramedullary increase in pressure. These are nerval reflexes caused by the innervation in the medullary cavity and are not reactions of the monomer, which may come into the circulation during the polimerization of bone cement. These reactions are very different from those caused by the fatal obstruction of the pulmonary blood vessels through bone marrow ingredients. This is the effect of an insufficient prevention of increase in medullary pressure during cement implantation.

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