Die Relativität der Ruhigstellung im Gipsverband

Quantitative assessment of bone defect healing by multidetector CT in a pig model

OBJECTIVE

To evaluate multidetector CT volumetry in the assessment of bone defect healing in comparison to histopathological findings in an animal model.

MATERIALS AND METHODS

In 16 mini-pigs, a circumscribed tibial bone defect was created. Multidetector CT (MDCT) of the tibia was performed on a 64-row scanner 42 days after the operation. The extent of bone healing was estimated quantitatively by MDCT volumetry using a commercially available software programme (syngo Volume, Siemens, Germany).The volume of the entire defect (including all pixels from -100 to 3,000 HU), the nonconsolidated areas (-100 to 500 HU), and areas of osseous consolidation (500 to 3,000 HU) were assessed and the extent of consolidation was calculated. Histomorphometry served as the reference standard.

RESULTS

The extent of osseous consolidation in MDCT volumetry ranged from 19 to 92% (mean 65.4 ± 18.5%). There was a significant correlation between histologically visible newly formed bone and the extent of osseous consolidation on MDCT volumetry (r = 0.82, P < 0.0001). A significant negative correlation was detected between osseous consolidation on MDCT and histological areas of persisting defect (r = -0.9, P < 0.0001).

CONCLUSION

MDCT volumetry is a promising tool for noninvasive monitoring of bone healing, showing excellent correlation with histomorphometry.

Development and clinical application of an external fixator monitoring system

A monitoring system for measuring movement occurring in a dynamic external fixator used to treat fractures is described. The system measures shortening during fracture healing, micromovement at the fracture site on weight bearing and detects pin loosening. The method of calibration including cadaver experiments is presented. The clinical application is described and the reasons for measuring movement are discussed.

Posttraumatic pseudarthroses--an analysis of development and treatment

The results of the analysis of 339 pseudarthroses in 326 patients are reported. We reviewed the aetiology and previous therapy of patients with pseudarthroses, their X-ray, case reports and assessed them clinically. We noticed instability as an important aetiological factor for development of non union, especially in combination with a bone infection. The evidence of failures due to a inadequate implant or due to an inadequate surgical technique is shown. Further aetiological factors are discussed. Our principles of treatment of pseudarthroses are outlined. The first principle is to achieve stability by operative procedure. The second is to indicate correctly bone grafting. The third principle concerns infected non unions in which extensive surgical revision is necessary. By carrying out this therapy we achieved bone healing in 95.4% of non infected pseudarthroses and in 86.8% of infected pseudarthroses.