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Biomedical subjects

G Bergmann

Publications and source records attributed to G Bergmann.

At least 109 records · Page 6Linked to original sources
PubMed1988

Multichannel strain gauge telemetry for orthopaedic implants.

In vivo measurements of the loads and deformations occurring in orthopaedic implants will allow future improvements to be made. This paper describes an extremely small telemetry for long term measurements with three strain gauges and methods for an absolutely safe implant design. Developed for measuring the load at hip prostheses, the telemetry can also be used for other implants. Its size makes feasible instrumentation of devices with only slight mechanical modifications. In addition to the description of our own measuring system, the paper gives a survey on the problems of telemetrized implants, on methods for measuring spatial loads, and on the investigations of other authors. Future publications will present in vivo measurements with this telemetry, among others on hip endoprostheses.

Equipment Design↗
PubMed1988

A nonlinear finite element analysis of interface conditions in porous coated hip endoprostheses.

We used a geometrically simplified finite element model to investigate load transfer between a porous coated hip endoprosthesis and a femur. Assuming both rigidly bonded and nonlinear interfaces, we analyzed fully and partially coated stems that had coatings of different elastic moduli. Our results indicate that maximum values for relative motion in the interface between bone and implant occur for implants with the same elastic modulus as compact bone. By comparison, interface motion is reduced by about half for Co-Cr-Mo alloy stems. We also showed that the elastic modulus of the porous coating had only a small influence on bone stresses.

Biomechanical Phenomena↗
PubMed1987

Effects of stem design and material properties on stresses in hip endoprostheses.

With the aid of a three-dimensional finite element stress analysis a parameteric study of the essential aspects of the femoral component of hip endoprostheses was carried out. Various designs were investigated; these included the prosthetic stem length, the existence or non-existence of the prosthetic collar and the elastic modulus of stem and cement. Variations in the stem length have only minor effects on the stress distribution for a stem length greater than 100 mm, but the elastic modulus of the prosthetic stem has a considerable influence on the stresses. A high elastic modulus of the stem increases the stresses in the stem but it decreases stresses in the cement. The cement stresses increase with an increase in the modulus of elasticity of the cement.

Bone Cements↗
PubMed1986

Studies in stuttering as a prosodic disturbance.

In two experiments, various aspects of prosody in adult male stutterers and nonstutterers were studied. The results showed that stutterers did not speak with a generally reduced pitch pattern, they were able to place sentence accent correctly but had difficulty executing this prosodic feature, stuttering episodes were located mainly on stressed syllables, a fixed timing pattern of speech enhanced fluency, and the intervals between stressed syllables were more variable in the speech of stutterers, even in symptom-free passages, than in the speech of nonstutterers. Results support the conclusion that stuttering, seen on the symptomatic level of disfluencies produced, is a prosodic disturbance.

Adult↗