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Biomedical subjects

H Plenk

Publications and source records attributed to H Plenk.

At least 91 records · Page 5Linked to original sources
PubMed1980

Detection of aluminum oxide and polyethylene wear particles from joint endoprostheses using cathodoluminescence and x-ray analysis in SEM.

A highly sensitive method to localize aluminum oxide or polyethylene wear particles in biological tissues is presented. Using the scanning electron microscope (SEM) with a special cathodoluminescence detector system, small amounts of these foreign materials can be visualized in simple frozen sections by their bright luminescence, even at low magnifications (200X). At higher magnifications, a differentiation of free as well as phagocytized aluminum oxide and polyethylene particles can be made due to their different behavior in light emission. In addition, aluminum oxide such as other metals can be identified by x-ray microprobe analysis. This combination of SEM with microprobe analysis and with the highly sensitive cathodoluminescence mode enables to detect and identify wear products from all the materials, commonly used in manufacturing artificial joint replacements.

Aluminum↗
PubMed1980

Collagenase activity of cartilage in rats with experimental lathyrism: a model of bone diseases.

Collagenolytic activity was estimated in skin and joint cartilage of lathyritic rats by means of a biological assay. Lathyrism was induced by feeding beta-aminopropionitrile fumarate for six weeks, and the lathyritic state was confirmed by characteristic radiographic, histomorphologic and biochemical findings. Both tissues in lathyritic animals revealed significantly increased collagenolytic activity in comparison with those of the control animals. Studies were performed using ethylendiaminetetraactate and normal rat serum to determine the origin of inhibition of the collagenolytic system inhibition. Since both agents showed no inhibition of collagenolysis, the highly increased collagenolytic activity in lathyritic skin and joint cartilage appears not to be derived from polymorphonuclear cells nor from serum, but from the tissue itself. Elevation of collagenase activity may be important with respect to the increased neutral salt solubility of collagen and hydroxyproline excretion observed in experimental lathyrism.

Aminopropionitrile↗
PubMed1980

[Experimental investigations on the growth of the vertebral column after dorsal spondylodesis (author's transl)].

To investigate the question which growth processes take place in dorsally stiffened vertebral regions, 4 vertebral segments each were dorsally fused in twenty-one pigs, using Harrington's distraction system in 20 cases. X-ray examination and histological measurements conducted with the aid of fluorochromosequential markings showed a more or less pronounced growth of the vertebral bodies and of the fusion mass in all animals. As a rule, the sequence of vertebral bodies overgrows the fusion mass in longitudinal direction, which always results in lordosis of the stiffened region. The longitudinal growth of the vertebral bodies, and even more so of the fusion mass, decreases with increasing postoperative observation time. The fusion mass shows actual internal growth which proceeds partly in diffuse manner in all directions, in the region of the clefts, i.e. as spondyloschisis, in some cases also in the same direction as with enchondral ossification associated with columnar chondrification. The growth of the fused mass does not depend on the formation of a pseudoarthrosis, although it is probably quantitatively promoted by pseudarthroses. The stimulus to longitudinal growth of the fused mass originates from the growing vertebral bodies, with probably varying influence of tensile and compressive forces.

Animals↗
PubMed1979

[Investigation of bone growth into porous metal implants (author's transl)].

Stainless-steel cylinders of different pore size were implanted into the tibia, and small tubes, 500 micrometers diameter, of the same material into the iliac crests of 19 rabbits. It was found that after three weeks ingrowing bone tissue anchored the cylinders if the pore size was adequate. The same applied to the tubes. A stable implantation was the prerequisite for the ingrowth of fibre-bone trabeculae. Additionally, the use of fibrinogen adhesive system seems to be advantageous for this anchorage. These results were established by mechanical tensile tests and morphological examinations.

Animals↗
PubMed1979

The effects of dynamic loading on intracalcaneal wood implants and on the tissues surrounding them.

The dorsal parts of the calcanei of rabbits were resected and replaced with similarly-shaped implants made of ash wood. In each case the Achilles tendon was reinserted into the projecting part of the implant so as to subject the latter to the dynamic loads generated by use of the limb. The implants were removed from some of the animals after 5 weeks and from the others after 14 weeks. They were evaluated by preparing undecalcified microtome sections and ground sections which were examined by light microscopy and microradiography. Some of the animals underwent vital staining so as to produce polychromatic sequential labelling of the calcaneal specimens. In the area of insertion of the Achilles tendon soft tissue grew into the larger pores of the wood and, in some cases, differentiated into cartilage. Every implant remained stably anchored in the calcaneus. In every animal the intracalcaneal part of the implant became surrounded by new bone which was in direct contact with the surface of the implant and which also formed in the pores of the wood, even all rabbits loaded the operated foot. The formation of new bone in and around the implants demonstrates the basic feasibility of using ash wood as an isoelastic implant material in bone.

Achilles Tendon↗
PubMed1979

A bioceramic endoprosthesis for the replacement of the proximal humerus.

In patients with malignant tumors in the region of the shoulder, radical resection can avoid amputation in most instances. To improve the function of the arm, endoprosthetic replacement of the defect is desirable. A three-component endoprosthesis made of a bioceramic material (aluminium oxide) was designed, implanted without bone cement. Fast anchorage to bone is achieved by using a conical sleeve, fixed upon the previously conically reamed humerus shaft. A stable primary fit is always feasible. Subsequent bone in growth into grooves inside the conical sleeve provides a permanent anchorage of the endoprosthesis. The authors experiences are based on implantations of 38 endoprostheses. The original diseases were primary malignant bone tumors in 19 patients, one case of "solitary" plasmocytoma and metastases into the proximal humerus in 16 patients. In two women, resection was made because of posttraumatic subcapital humeral pseudarthrosis. The follow-up study includes only those 27 cases operated on at least one year ago. 12 of the 14 patients with primary tumors have been surviving for 12-55 months (range 27.4) without signs of metastases or recurrent disease. Seven patients with metastases died of their original diseases after 7.7 months on the average. Owing to extensive resection of the shoulder musculature the mobility in the shoulder joint is considerably reduced. All the patients have good movement of the elbow joint and free function of the hand.

Activities of Daily Living↗
PubMed1979

Ultrastructure of skeletal muscle after CO2-laser incision.

The immediate effect of CO2-laser incision to the dorsal skin and underlying muscular tissue of rats was studied by light and electron microscopical methods. In the subcutaneous layer of skeletal muscle cells an increased susceptibility was found, resulting in distinct zones of cellular changes which are attributed mainly to thermal effects of the laser beam. The importance of these findings for the surgical application of lasers is discussed.

Animals↗
PubMed1978

Extracortical attachment of bioceramic endoprostheses to long bones without bone cement.

Dense, highly pure A12O3 ceramic not only shows excellent wear resistance and tissue biocompatibility, but also has sufficient mechanical strength for loaded endoprostheses. The necessary diameter size of the material to sustain adequate shear stresses can be achieved, if the endoprosthesis is attached extracortically to the conically truncated long bone according to the principle of the conical sleeve. Extracortical attachment of the endoprosthesis causes minor nutritive damage since long bones derive their vascular supply mainly from the medullary cavity. In this way a primary stable and loadable connection is established, which is a prerequisite for permanent anchorage of the implant through new bone formation. After experiments in 12 dogs bioceramic endoprostheses were implanted in a total of 40 human patients using this technique of extracortical attachment (12 hip joints, 24 proximal humeri, 4 special constructions). Thirty-six of these implants were stable after observation periods ranging from one to 49 months. A stable anchorage of the prostheses to the pre-existing bone through new bone formation could be demonstrated histologically. The above preliminary results show that bioceramic endoprostheses can be "incorporated" in the skeleton and possibly also withstand the functional stresses.

Adult↗
PubMed1977

A perfusion method of incubation to demonstrate horseradish peroxidase in bone.

A perfusion method of incubation to show horseradish peroxidase in the bone of young mice is presented. After perfusion fixation, the incubation medium is perfused from the descending aorta into the entire lower half of the animal. From the vessels there is good penetration of the medium into all tissues. This allows the preparation of any one perfused bone to ground-, semithin-, and ultrathin sections. Differences in peroxidase distribution in the entire bone suggest regional differences in vascular supply. The tracer enzyme diffuses freely from the vessels into the extracellular fluid of bone. 3 min. after injection, peroxidase is found between all bone lining cells and in osteocyte lacunae.

Animals↗
PubMed1977

[Biocompatibility of wood in bone tissue (author's transl)].

Alcohol-extracted and sterilised cylinders of ash- and birchwood were implanted into the tibia of rabbits. The selection criteria of these two wood species were thoroughly described. 28 implants were evaluated after 3, 5, 14 and 32 weeks using undecalcified microtome sections and ground sections employing polychromatic sequential-labelling and microradiography. In spite of a foreign-body-tissue reaction new bone is formed around the implants and within the pores of the wood as well. Both wood species therefore seem to be suitable implant materials, which were anchoraged by the bone itself. A tensile strength and elastic properties comparable to bone and simple handling would be the advantages of this material.

Animals↗
PubMed1977

[Ultrastructure of bone-tissue cells].

The ultrastructure of bone cells is delineated by investigation of bone tissue in young mice. The characteristic cytoplasmicstic pattern of osteoblasts, osteocytes and osteoclasts is described. The morphologic findings are discussed with respect to the function of these cells.

Animals↗
PubMed1976

[Homologous articular cartilage transplantation in animal experiments. Preliminary studies on sheep (author's transl)].

Homologous articular cartilage without subchondral bone instead of the usual osteochondral grafts was transplanted in sheep. The transplants were fixed to the host by a biological tissue adhesive based on fibrinogen clotting. Light- and electronmicroscopic studies showed viable transplants up to 7 months and a stable bony union with the host through endochondral bone formation. A additional external fixation of the joint after transplantation or the use of a conventional cyanoacrylate tissue adhesive failed to achieve positive results. The relations of these preliminary findings for restorative techniques of articular cartilage defects are discussed.

Animals↗