D Hilweg

University of Münster, Muenster, North Rhine-Westphalia, Germany

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Publications (11)16.49 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The ongoing search for causes (and strategies for prevention) of low back trouble in sub-groups of the population exposed to heavy physical exertions or whole body vibration requires reliable data on the prevalence of lower-spine overload damage. Because published reports on this topic are rare and mostly qualitative, the present study was initiated to assess, objectively and quantitatively, overload damage to vertebrae and intervertebral discs. Part I of the work has involved the establishment of a normative database of shape parameters from measurements of 683 (539 male, 144 female) lateral radiographic views of the thoracolumbar spine of young (17–30 years), healthy subjects. In addition, age-related shape alterations were explored from measurements of 364 male middle-aged (31–57 years), non-exposed controls. Advanced methods for shape analysis and shape parameter construction were required, and duly developed, in order to minimise the influence of confounding factors such as radiographic magnification, image distortion, axial rotation or lateral tilt. The results revealed that the variation in shape parameters varies between 2% and 10% within the group of normals (this being largely biological variability as opposed to measurement error). Within this normal group subtle but statistically significant differences due to gender and geographic origin were observed. Comparison of the normals with the controls revealed only slight, but clearly demonstrable differences. The narrow range of ‘normal shape’ together with the high accuracy of shape analysis are the foundation for Part II of this study which will involve a comparison of exposed cohorts with the normal standard (adjusted for ageing effects). This will, for the first time, enable objective quantification of the prevalence of overload damage to the spines of persons exposed to heavy physical stresses and whole body vibration, and thus form the basis of a scientific rationale for recommendation of safety guidelines.ZusammenfassungUrsachenforschung und Prävention auf dem Gebiet der Rückenbeschwerden bei Personen, die körperlich schwere Arbeit leisten oder einer Ganzköpervibration ausgesetzt sind, erfordern verläßliche Daten zum Vorkommen primär-mechanisch bedingter Überlastschäden der thoracolumbalen Wirbelsäule. In der wissenschaftlichen Literatur finden sich sehr wenige Untersuchungen zu diesem Thema; sie enthalten im Wesentlichen lediglich qualitative Aussagen. Die vorliegende Arbeit hat sich daher zum Ziel gesetzt, die Prävalenz von Überlastschäden an Wirbeln und Bandscheiben objektiv und quantitativ zu bestimmen. Zu diesem Ziel wird in Teil I der Arbeit eine Datenbasis der Formparameter der Wirbelsäule gesunder, junger Personen erstellt. Sie basiert auf der Vermessung von 683 (Röntgen0Seitaufnahmen (539 männlich, 144 weiblich Alter 17–30 Jahre). Altersbedingte Veränderungen werden durch die Vermessung von 364 Aufnahmen einer nicht-exponierten, 31–57 Jahre alten Kontrollgruppe bestimmt. Neue Methoden der Formbeschreibung und der Formanalyse wurden entwickelt; dadurch war es möglich, störende Einflüsse von Röntgenvergrößerung, Bildverzerrung, sowie Rotation und Seitneigung der Wirbelkörper klein zu halten. Im Ergebnis zeigen die verschiedenen Formparameter der Normalgruppe eine Streuung zwischen 2% und 10%. Diese Streuung ist im Wesentlichen durch die biologische Variation bedingt; Meßfehler geben nur einen kleinen Beitrag. Innerhalb des Normal-Kollektivs zeigen sich geringe, jedoch hochsignifikante Unterschiede je nach Geschlecht und geografischer Herkunft. Die Kontrollgruppe weist gegenüber der Normalgruppe nur geringe, jedoch eindeutig quantifizierbare Unterschiede auf. Die niedrige Streuung der Formparameter innerhalb der Normalgruppe und die hohe Präzision der Formanalyse bilden die Grundlage für Teil II der Arbeit, in der die Form der Wirbelsäule exponierter Personen mit der Normalform (bereinigt von Alterungseffekten) verglichen werden soll. Dann werden zum ersten Mal quantitative Daten zur Prävalenz von Überlastschäden der Wirbelsäule von Personen, die körperlich schwer belastet werden, oder die einer Ganzkörpervibration ausgesetzt sind, verfügbar sein. Dieses Wissen wird die Entwicklung wirksamer Maßnahmen der Prävention fördern.RésuméLa recherche actuelle des causes (et stratégies préventives) de problèmes lombaires de sous groupes de patients exposés à d'importants efforts physiques ou de vibrations corporelles suscite de fiables données en regard de la fréquence de dommages du bas de l'épine dorsale causés par le surmenage. Comme les rapports publiés sur ce sujet sont rares, et pour la plupart qualitatifs, l'étude suivante a pour intérêt d'étudier à la fois objectivement et quantitativement les dommages des disques vertébrés et invértebrés causés par le surmenage. La partie I du travail consiste en l'établissement de bases de données de référence des paramètres liés à la forme de la colonne vertébrale d'un échantillon de 683 (539 hommes et 144 femmes) vues radiographiques latéraux des lombaires de jeunes agés de 17 à 30 ans en parfaite santé. Par ailleurs, les modifications de l'échine en fonction de l'âge ont été étudiées à l'aide d'un prélèvement de 364 hommes d'âge moyen (31–57 ans), non exposés au surmenage. On demande des méthodes avancées pour analyser la forme de l'épine dorsale et pour établir des paramètres des disques lombaires; méthodes suffisament développées pour minimiser l'influence de facteurs cachés tels le grossissement radiographique, la distorsion de l'image, la rotation axiale ou l'inclinaison latérale. Concernant le groupe de sujets considérés comme ‘normaux’, les résultats ont revélé une variation de variance des paramètres de 2 à 10% (cet écart est du à des diversités biologiques opposées à des erreurs de mesure) et de subtiles mais statistiquement importantes différences engendrées par le genre et l'origine géographique des patients. De lègers mais notables différences ont été observées lors de la comparaison des ‘normaux’ et des 'controls. La partie II de ce travail est basée sur l'étude de l'étroite échelle de la forme ‘normale’ de l'épine du dos et de la haute précision des analyses de celle-ci en comparant les groupes exposés au surmenage aux ‘normaux’ (ces derniers ajustés en fonction de l'âge). Ceci permettra, pour la première fois, une quantification objective de fréquence de dammages des colonnes vertébrales causés par le surmenage exposé à d'importants stress et de vibrations corporelles. De ce fait, un raisonnement scientifique basé sur cette étude contribuera à la mise en place de recommendations de directives de sécurité.
    Clinical biomechanics (Bristol, Avon) 01/1994; · 1.76 Impact Factor
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    ABSTRACT: Rupture of the thoracic aorta is usually widespread and fatal. Rupture limited by the lung and aorto-bronchopulmonary fistula are rare. We report two patients with a contained perforation of the thoracic aorta, who presented with haemoptysis. Chest radiographs demonstrated an aortic aneurysm and pulmonary haemorrhage in the first, while in the other perforation of an atherosclerotic aorta with a pulmonary haematoma was misinterpreted as bronchial carcinoma. In both cases contrast enhanced CT clearly demonstrated the abnormality in the aorta and the pulmonary haemorrhage. Since aortography often fails to demonstrate a perforation, CT or MRI should be performed early in patients with suspected rupture of the thoracic aorta.
    Der Radiologe 08/1991; 31(7):348-51. · 0.47 Impact Factor
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    ABSTRACT: Vertebral insufficiency fractures may result from excessive loading of normal and routine loading of osteoporotic spines. Fracture occurs when the mechanical load exceeds the vertebral compressive strength, i.e., the maximum load a vertebra can tolerate. Vertebral compressive strength is determined by trabecular bone density and the size of endplate area. Both parameters can be measured non-invasively by quantitative computed tomography (QCT). In 75 patients compressive strength (i.e., trabecular bone density and endplate area) of the vertebra L3 was determined using QCT. In addition, conventional radiographs of the spines were analysed for the prevalence of insufficiency fractures in each case. By relating fracture prevalence to strength, three fracture risk groups were found: a high-risk group with strength values of L3 less than 3 kN (kilo Newton) and a fracture risk of 100%, an intermediate group with strength values from 3 to 5 kN and a steeply increasing risk with decreasing strength, and a low-risk group with strength values greater than 5 kN and a fracture risk near 0%. Biomechanical measurements and model calculations indicate that spinal loads of 3 to 4 kN at L3/4 will be common in everyday activities. These data and the results described above suggest that spines with strength values of L3 less than 3 kN are at an extremely high risk of insufficiency fractures in daily life. Advantages of fracture risk assessment by strength determination over risk estimation based on clinically used trabecular bone density measurements are discussed.
    European Journal of Radiology 01/1991; 13(1):6-10. · 2.51 Impact Factor
  • M Biggemann, R Kappes, D Hilweg
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    ABSTRACT: The clinical and radiographic aspects of an unusual case of mediastinal and bronchovascular amyloidosis are presented. Besides hilar and mediastinal lymphadenopathy, extensive amyloid deposition in the peribronchial and perivascular connective tissue sheaths can be observed. Plain film radiographs and CT demonstrate an uncommon pattern of increased bronchovascular markings, which is discussed. Because of peribronchial amyloid deposits, bronchoscopy is of no help in demonstrating this special type of tracheobronchial amyloidosis.
    Der Radiologe 08/1990; 30(7):344-6. · 0.47 Impact Factor
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    ABSTRACT: Testing 98 motion segments we investigated the possibility of a prediction of the compressive strength of thoracolumbar vertebrae by QCT. The ultimate compressive strength can be predicted from the density of the trabecular bone and from the size of the endplates--both determined by QCT--with an error of 1 kN. The increase of compressive strength in craniocaudal direction is calculated at approximately 0.3 kN per anatomical level. This variation is due to the increase of the endplate areas.
    RöFo - Fortschritte auf dem Gebiet der R 10/1989; 151(3):322-5. · 2.76 Impact Factor
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    ABSTRACT: The compressive strength of 98 specimens of motion segments of human thoracolumbar spines was measured. In addition, the density of the trabecular bone in the midplane of the vertebrae was assessed by quantitative computed tomography (QCT); the size of the vertebral endplates was measured by CT as well. The results show that the compressive strength of thoracolumbar vertebrae can be predicted from the product of density and end-plate area, with an error of estimate of 1 kN. The data of the experiment allow for an in vivo prediction of the strength of vertebrae to quantify the risk of fracture in physically very demanding tasks, to support expert opinion in trauma cases, or to assist in therapeutic decisions in cases of severe osteoporosis.
    Spine 07/1989; 14(6):606-10. · 2.16 Impact Factor
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/1989; 151(09):322-325.
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    ABSTRACT: The ultimate compressive strength of 36 thoracolumbar vertebrae was determined experimentally. In addition, the trabecular bone mineral content was measured by single energy quantitative computed tomography. The areas of fractured endplates were also determined by computed tomography. The results show that a linear relationship exists between the compressive strength and the product of bone density and endplate area. These data allow an in vivo prediction of vertebral body strength using a noninvasive method with a standard error of estimate amounting to less than 0.95 kN.
    Skeletal Radiology 02/1988; 17(4):264-9. · 1.74 Impact Factor
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    ABSTRACT: Fatigue fracture of human lumbar vertebrae under cyclic axial compressive load is investigated between 1 and 5000 load cycles and for load magnitudes between 30 and 70% of the ultimate compressive strength of human lumbar vertebrae. In addition, it is shown that the ultimate compressive strength of human lumbar vertebrae can be predicted from trabecular bone density determined by quantitative computed tomography in combination with a measurement of the area of the vertebral end plate.
    Clinical Biomechanics 05/1987; 2(2):94-6. · 1.87 Impact Factor
  • M Biggemann, D Hilweg
    RöFo - Fortschritte auf dem Gebiet der R 02/1985; 142(1):104-5. · 2.76 Impact Factor
  • M. Biggemann, D. Hilweg
    Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/1985; 142(01):104-105.

Publication Stats

301 Citations
16.49 Total Impact Points

Institutions

  • 1989–1991
    • University of Münster
      Muenster, North Rhine-Westphalia, Germany
  • 1990
    • Bethesda Krankenhaus
      Hamburg-Mitte, Hamburg, Germany