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Biomedical subjects

M Ungethüm

Publications and source records attributed to M Ungethüm.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

[Endoprosthetic replacement of the shoulder joint. Possibilities and their analysis].

Functional and anatomic characteristics of the shoulder girdle are special problems, that have to be solved in the process of using an artificial joint replacement to improve the function of a painful shoulder, which is restricted in movement. Seen from a biomechanical point of view, besides a safe fixation of the prosthesis the stability and kinematic of the artificial joint are of considerable importance for the success of the endoprosthetic treatment. The efforts of meeting these requirements by a respective prosthesis design led to a variety of prosthesis types. This study shows the possibilities for prosthetic replacement of the shoulder joint and comprises an analysis of all systems, which are available on the market, as well as of the patent applications of the past 15 years. The prostheses are listed according to their stability. Relative to the state of destruction of the joint unconstrained prosthesis types with completely free and partially restricted mobility, as well as constrained types of joints are being discussed.

Biomechanical Phenomena↗
PubMedDate not supplied

[Studies of explanted shot-peened osteosynthesis plates].

Shot peening is a cold-working process to increase the fatigue life of osteosynthesis plates. Using ceramic particles for this process we observed no change in the corrosive properties of the plates. Up to now we implanted 37 shot peened osteosynthesis plates for fixation of intertrochanteric osteotomies. 13 plates were explanted after an average time of 14,2 months. We investigated the plates as well as the tissue surrounding the implants. Metallurgic specimens showed not so many pittings at the shot peened plates in the region of the screw hole as were seen at the polished plates after the same period of implantation. By histological investigation corrosive products or fretting particles were detected mostly in the region of the screws. Only a few metal particles were found in the region between the screw holes. Analysing the elements which were black or red-brown coloured in histological specimens by scanning electron microscopy we identified these particles as metal components. But there was a great difference in the relation of the particles found in the tissue compared to the components forming the plates alloy. This is due to the difference of distribution of the metal components at the surface of the implant in comparison with the central part of the plate. These austenitic stainless steels are protected by an enrichment of Cr in the surface layer. This could be shown in the shot peened plates as well as in the polished plates. The results of our investigations show a corrosive behaviour which is at least equal at both plates types in laboratory investigations as well as after implantations in men.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMedDate not supplied

[Toxicology of metals and biocompatibility of metallic implant materials].

Based on general toxicological knowledge and the notorious measurements of corrosion parameters this paper is an attempt to define the biocompatibility of metallic materials used for implantation in the human body. Mentioned are essentially those implant materials and its metallic elements which are subjectmatter of a standard specification. The previous experiences concerning "metal allergy" are shortly recapitulated. Model conceptions about the mechanisms of tissue reaction to metallic elements are indicated.

Biocompatible Materials↗
PubMedDate not supplied

[Experiences with hip joint endoprosthesis model PM for cement free implantation].

This is a report about the experiences made with a new hip prosthesis for cementless fixation. Considering the results gained hitherto, this system can be recommended for both primary and exchange operations. However, as for all other prostheses for cementless fixation, an exact operating technique is indispensable for thorough adaption of the inner femur surface to the shape of the prosthesis.

Aged↗
PubMedDate not supplied

[Wear of the polyethylene components of endoprostheses following clinical application].

13 various hip joint and knee joint polyethylene components, previously removed from patients after an implantation period of 1.5 to 4 years, were tested and showed an obvious damage of the sliding surface. Macroscopic and microscopic investigations performed by light and scanning electron microscopy revealed an extreme wear of the polyethylene surface respectively an unregular wear at the component's border up to the mm-range. Additional specific X-ray and infrared spectrometric analyses proved in the clear majority of all cases the contribution of bone cement to increased abrasion and its influence upon the intensity of wear. Surplus bone cement which had not been completely removed from the prosthesis component or loosening of prosthesis components are considered as reason for inclusion of bone cement particles between the sliding surfaces.

Bone Cements↗
PubMedDate not supplied

[A new test procedure to examine the stability of external fixation clamps--demonstrated with the Stuhler-Heise external fixation system (author's transl)].

Experimental investigation of stabilty for examination of the efficiency of external fixation clamps required different testing procedures and measuring arrangementsz which is due to variant assessment parameters and natures of load. Here is a description of a measuring equipment which could be applied for all important cases of load. In relation to the entire experimental arrangement it also enables the testing of all external fixation assemblies. Deviations of the poroximal fragment caused by loading, are considered as assessment parameters of the stability. This measuring set was practically applied on simulated defect fractures, stabilized by the Stuhler-Heise external fixation system. During a combined bending strain the stability degree of various two-dimensional as well as three-dimensional external fixation clamps for application on tibias was determined.

Bone Nails↗