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Biomedical subjects

U Boenick

Publications and source records attributed to U Boenick.

87 records · Page 5Linked to original sources
PubMed1975

[Result of a user inquiry for the improvement of hand propelled wheelchairs (author's transl)].

The contribution describes the results of an inquiry of handicapped wheelchair drivers which have been compiled by evaluating 3482 questionnaires with 268,144 informations using an IBM 1130 computer. Divided into "rim" and "lever" propulsion the driving quality, the manoeuvrability, the seat comfort, problems of driving mechanism and the transportation suitability as well as the wear of the vehicles are analysed. Finally some recommendations for the design of future wheelchair models are given on the basis of the observed drawbacks.

Activities of Daily Living↗
PubMedDate not supplied

[Kinetic and kinematic gait analysis before and after total knee endoprosthesis implantation].

OBJECTIVE: The aim of the present paper was to make an objective assessment of the surgical outcome after primary knee endoprosthesis implantation by means of gait analysis. METHOD: Kinetic and kinematic parameters of gait pattern were recorded using multi-component measuring platforms integrated into a treadmill and an optoelectric measuring system. 20 patients were investigated preoperatively and on average 14 and 28 weeks postoperatively. RESULTS: Preoperatively, on the affected side, the leg was used for a shorter time, but with much higher maximum forces. Mobility was reduced in the affected joint, in the adjacent hip joint, and in the contralateral joints when walking. After endoprosthesis implantation, the gait pattern approximated that of the reference group. The gait symmetry increased, and the time and force-related loading of the operated leg and the extent of mobility of the contralateral knee and both hips increased up to 28 weeks postoperatively. The clinical score according to Aichroth et al. showed a correlation with the measured values of the gait analysis at all times (p < 0.05). CONCLUSION: Mono-articular degenerative changes of the knee have a negative effect on the function of adjacent and contralateral joints. Endoprosthesis implantation then leads to a normalisation of pathological motion patterns, both in the operated and in the adjacent and contralateral joints. However, normal values were not yet achieved 28 weeks postoperatively, which demonstrates the possibility for further functional improvement depending on the continuity of rehabilitation.

Aged↗
PubMedDate not supplied

[Long-term stability of glass ionomer cement--method and results].

Glass ionomer cement already has many applications as a filling and fixation material in dentistry, and is now also being considered for use as a bone cement in orthopedics. The reason for this is that the high temperature that develops during polymerization of the PMMA bone cement currently employed, would then be avoided. On the other hand, however, it has the disadvantage of reduced mechanical strength. In order to evaluate the suitability of glass ionomer cement as a bone/implant interface it is necessary to supplement our present knowledge of its static properties by investigating its properties under dynamic loading conditions. This article describes an appropriate test method, the design of the testing set-up, and the results obtained.

Biomechanical Phenomena↗
PubMedDate not supplied

[Risk analysis of medical products. Implementation of risk analysis exemplified by the spongiosa cannulated screw].

The Medical Devices Act (Medizinproduktegesetz = MPG) took effect in Germany on 01. 01. 1995, and replaced (with the exception of diagnostic laboratory devices) the previously binding MedGV with a transition period ending on 13. 06. 1998. The new German act is the implementation of the EC directive on active implantable medical devices (90/385/EWG) and the directive on medical devices (93/42/EWG). The EC directive 93/42/EWG on medical devices permits the manufacturer of a medical device to chose the conformity assessment procedure. All medical devices are subject to conformity assessment procedures, and are awarded the EC mark through Appendix II, III, VII or VIII. All these appendices contain information about the need for carrying out assessment and the obligation to provide a written description of the risk analysis for a medical device. Risk analysis is a common method that verifiably ensures that the basic requirements of EC Directive 93/42/EWG on medical devices are met by the product. It is obvious that risk analysis is of central importance to the legal measures for ensuring appropriate device safety. The present paper presents and assesses various methods of risk analysis.

Bone Screws↗
PubMedDate not supplied

The effects of the use of piezoelectric motors in a 1.5-Tesla high-field magnetic resonance imaging system (MRI).

PURPOSE: This paper presents the results of an experimental investigation with two different rotatory piezomotors in a closed 1.5 Tesla high-field MRI. The focus of the investigation was on testing the functionality of these motors within the MRI and to determining the image interference they caused. MATERIALS AND METHODS: To obtain a differentiated estimate of the interference the motors were tested in both the passive (turned off, i.e. without current flow) and active (turned on, i.e. with current flow) state during MRI scanning. Three different types of sequences were used for the test: Spin-Echo (SE), Gradient-Echo (GE) and Echo-Planar Imaging (EPI). A plastic container filled with a gadolinium-manganese solution was used for representation of the artefacts. The motors investigated were placed parallel to the container at predetermined distances during the experiment. RESULTS AND CONCLUSIONS: The results show that the motors investigated suffered no functional limitations in the magnetic field of the MRI but, depending on the type of motor, the measurement distance and the state of the motor, the motors had different effects on the sequence images. A motor in the off-state placed immediately next to the object to be measured mainly causes artefacts because of its material properties. If, on the other hand, the piezomotor is in the on-state images with strong noise result when the motor is immediately next to the object being measured. The images regain their normal quality when the motor is approximately at a distance of 1 m from the object being investigated. Driving the motor inside the MRI, therefore, is only to be recommended during the pauses in scanning: this delivers artefact-free images if minimal, motor-specific distances are kept to. With regard to the three different types of sequences it was determined that the SE sequence was the least sensitive and the EPI sequence the most sensitive to disturbance. The GE sequence showed only minimal differences to the SE sequence with regard to signal-to-noise ratios. Since it requires considerably shorter scan-times it can be considered to be the most effective type of sequence under these conditions.

Artifacts↗
PubMedDate not supplied

[Possibilities of myoelectric control of artificial limb prostheses].

This article summarizes the main possibilities for myoelectrical control of prostheses and other rehabilitation devices. In this context fundamental cybernetic aspects, the question of achieving optimal differentiation of antagonistic signals, and 16 possibilities of myoelectrical control, ranging from simple n-state threshold detectors to rate sensitive controllers, to intelligent controllers and pattern recognition techniques, are considered.

Artificial Limbs↗