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Biomedical subjects

P Edholm

Publications and source records attributed to P Edholm.

At least 19 recordsLinked to original sources
PubMed1984

The stability of union in tibial shaft fractures: its measurement by a non-invasive method.

The stability of the union in tibial shaft fractures was followed by repeated non-invasive radiographic measurement of a deflection induced in the area of the fracture. By means of a Shift Comparator the difference in the angle between the two fragments before and during application of the deflecting force can be measured. The relative measure of the strength of the union is furnished by a quantity, the deflection ratio, which is based on the quotient of the induced deflection by the magnitude of the applied bending moment. When this ratio falls below a certain value the union is considered to be stable enough for full weight bearing during walking. A plot of the deflection ratio against time, with logarithmic scales on both axes had a negative slope and was more or less linear. This graph can serve as an aid in detecting the course of union, in deciding when the cast should be removed, and in detecting any irregularity in the process of union. In the management of 207 fractures of the tibial shaft 508 such deflection measurements were performed.

Biomechanical Phenomena↗
PubMed1984

Stability of union after tibial shaft fracture. Analysis by a non-invasive technique.

The stability of union following the conservative treatment of tibial shaft fractures has been examined in 157 patients by a non-invasive method. With this technique it is possible to ascertain when the fragments are united and whether the strength of union is sufficient for full weight-bearing without protection. The mean time required for union was 14.0 +/- 9.2 weeks, with a range of 4 to 48 weeks. In 31 cases union was judged to be delayed; in 22 of these, intended operations were avoided because repeated stability determinations indicated progressive union. Of nine fracture variables examined, the only ones which significantly affected the time required to achieve union were the age and the weight of the patient. Irrelevant factors were the type and level of the fracture, the energy of trauma, soft-tissue injury and the presence of multiple injuries.

Adolescent↗
PubMed1983

Comparison of radiographic images. A new method for analysis of very small movements.

A new method, shift comparisoN, for comparing 2 radiographic images is described. The method may be used for many purposes, but is particularly suitable for detecting small provoked motions between skeletal parts. Defective union in fractures or osteotomies is easily diagnosed by such a comparison. Films are exposed before and during the application of force to one of the fragments. By examining the films in the Shift Comparator small movements caused by the force may be detected. The technique has also been used for measuring the development of stability of union of tibial fractures by determining th deflection of the fracture caused by a bending moment.

Biomechanical Phenomena↗
PubMed1978

Transverse tomography with incoherent optical reconstruction.

A thin layer of an object can be imaged by reconstruction from a so-called sinogram. It is produced by an x-ray fan beam rotating around the object while a recording film is moved in a direction perpendicular to the plane of the fan beam. Before reconstruction the sinogram image is convoluted according to a special function to remove artifacts consisting of spurious shadows between different object elements. The reconstruction is done from the convoluted sinogram by means of a back projector, which operates according to a prinicple that is the reverse of the recording of the original sinogram. Tomograms of phantoms, pork chops and the head of a dog show that the process is capable of high spatial resolution but is limited by low contrast.

Animals↗
PubMed1977

Knee instability and tibial osteotomy. A clinical study.

Twenty-one gonarthrosis patients were preoperatively assessed according to a newly developed orthoradiographic technique ("three-point measurement") and followed up for 2-3 years postoperatively using this technique. The medio-lateral instability of the knee joints was not influenced by the operation. The varus/valgus deviation was under-corrected, on average, but the deviation did not increase significantly with time after the operation. Judging from this pilot study the three-point measurement technique supplies relevant information and it is now being used in a prospective study on high tibial osteotomy in gonarthrosis.

Aged↗
PubMed1976

Attenuation equalizing filter in diagnostic radiography. Advantages calculated by a Monte Carlo technique.

The value of an attenuation equalizing filter (equalizer) has been examined by calculation using a Monte Carlo technique. The contrast enhancement caused by the equalizer is the net result of three factors: (1) The first factor arises from the contrast change caused by the difference in detector characteristics at the different energies absorbed in the detector with and without equalizer. (2) The second factor is due to the contrast change caused by the different ratios of primary to total radiation reaching the detector. (3) Finally, the third factor describes how the transparency of the object is changed by the different primary filtration with equalizer. An example is given of the reduction in radiation energy absorbed by the patient and the question of how far the attenuation equalization can be driven is discussed.

Computers↗
PubMed1976

Knee instability. An orthoradiographic study.

An orthoradiographic method for preoperative assessment of mediolateral instability and varus/valgus deviation in gonarthorsis is presented. A special definition of the varus/valgus deviation is given. The examination technique has been tested on 15 young, healthy subjects with no clinical signs or symptoms in their knee joints. To test the accuracy of the method, seven of the subjects were re-examined at a later date.

Humans↗