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Biomedical subjects

G Heimke

Publications and source records attributed to G Heimke.

46 records · Page 3Linked to original sources
PubMed1975

Morphological and biomechanical aspects of Al2O3 ceramic joint replacement. Experimental results and design considerations for human endoprostheses.

Four different acetabular replacement designs and 2 femoral head replacement designs made out of high density alumina ceramic have been tested in sheep with postoperative survival times of up to 11 months (Frialit 99: Al2O3 99.6%, MgO 0.4%). It can be concluded from these experiments that a cement free implantation technique with alumina requires a primary rigid fixation of the implant to bone, with the possibility for new bone growth along the ceramic and into grooves and macroscopic holes for further interdigitation. Three different solutions for the acetabular component can be recommended for human application. In addition, an all ceramic femoral prosthesis has been tested for bending strength in its neck region. Twenty prostheses have been factured, all of which showed values for bending strength far higher than the physiological neck fracture level (900 kp/cm2). The present state of development of all ceramic prostheses is discussed. Up to now, the development of fibrous tissue between the bone and the ceramic implant has caused reservations with human implantation. The direct definite anchorage problem has to be resolved first.

Acetabulum↗
PubMed1975

[The alumina oxide ceramic-metal composite endoprosthesis. A new hip endoprosthesis for partially cement free implantation (author's transl)].

The favorable combination of properties of dense, pure Al2O3-ceramics as a material for endoprostheses of the high load bearing joints have been confirmed in more than 4 years of experimental work with different types of animals. During this period Al2O3-ceramic parts for total hip replacement have already been developed and tested as well as the special instrumentation and the technique of the surgical procedure concerned. Based on these experiences a new total hip endoprostheses together with its complete technique for the operation is presented with which an improved alternative for replacements of Weber-Huggler-prostheses is offered and the application of total hip replacements can be extended to patients below 60 years of age.

Aluminum↗
PubMedDate not supplied

[Postoperative pain in cement-free femur shaft prosthesis].

With practically all hip endoprosthesis systems the femoral components of which are implanted cement-free irritations in the femoral region persisting for up to two years p.o. have been reported significantly more frequently than with cemented shafts. The discussion of this observation is based on the fact that stems inserted cement-free are mostly press-fitted into the surrounding bone, thus, creating a completely different stress and strain field as compared to cemented shafts. The usually spontaneous disappearance of these initial irritations is attributed to remodelling reactions which, controlled by the load distribution in the surrounding bony tissue which, in turn, is mainly controlled by the shape of the prosthesis, results in the formation of well load bearing bony structures along steps and other surface undulations along the proximal part of the prosthesis.

Body Weight↗
PubMedDate not supplied

[Experimental results of stepped titanium shafts for hip endoprostheses].

Among the materials which can be used for hip prostheses to be implanted without bone cement, ceramics and titanium possess the best overall properties for insuring long-term stability in the light of present knowledge. However, considered separately, the two materials are most suitable for different special requirements. Results of long-term animal experiments conducted by different working groups on functionally stressed hip and tooth-root implants made of bio-inert Al2O3 ceramic and titanium have furnished knowledge of the possibilities and limitations of the adaptation reaction of the bone tissue. The present authors investigated whether, by combining Al2O3 ceramic and titanium, a cement-free total hip replacement can be adapted to specific local stresses, taking biomechanical rules and anatomical factors into account. In recent experimental series it proved possible to limit the problems which had occurred in previous series, reported elsewhere. Positive results in dogs led to a human implant which has so far been used 15 times, with Al2O3 (FRIALIT) acetabula and heads, which have been implanted successfully for a number of years, in combination with the new stepped titanium shaft. In addition to a short review of follow-up findings thus far, the results of the experimental investigations are presented.

Animals↗