Biomechanics of fracture healing.

Internal fixation of fractures alters the physical environment of living bone. The authors have studied the reaction of living bone to force and motion, mainly in sheep. Cortical bone does not undergo pressure necrosis when compression is applied in internal fixation.

[A method for morphometry of bone formation using fluorochromes (author's transl)].

A reliable morphometric determination of newly formed bone requires a continuous labeling of the tissue of interest. A technique is described which uses the fluorochromes Calcein and Xylenolo-range as bone labels. Image contrast in the fluorescence microscope can be increased by means of special filter combinations to permit data collection by computer-compatible video-systems.

[A method of quantitative determination of tissue tolerance in decreased relative movement between implant and tissue].

A method of testing in vivo tissue tolerance to different implant materials is presented. It aims at reduction of variance due to mechanical irritation at the tissue-implant interface through the use of cylindrical implants with grooves. The special type of histological preparation which is necessary and problems encountered when using these techniques are described.

[Importance of the friction between plate and bone in the anchoring of plates for osteosynthesis. Determination of the coefficient of metal-bone friction in animal in vivo].

In mechanical devices in general the friction plays an important role in force transmission. To find out about the magnitude of frictional forces between internal fixation plate and bone in vivo, simultaneous strain recording in plated bone and instrumented plate were performed. After 3 weeks of implantation the torque applied to a single plate-screw was set to definite levels.

[Inclined plate screws - in vitro measurement of the stability of transverse osteotomy of tibia].

A compression plate which is exactly contoured to the bone surface produces asymmetric compression: only part of the cortex near the plate is compressed. Therefore a compression plate is not meant to be used selfstanding, it will rather be combined with additional means. Two of these have been studied: the increased stability provided by the use of lagging, inclined plate screws was compared to the one provided by the spring effect of a plate prebent for central elevation.

[Vaccination against staphylococcal infections in animal experiments].

Based on favour and clinical observations we have undertaken to observe the effect of vaccination against staphylococcic infection in the mouse. A standard amount of staphylococcus was used together with a metal implant. After two weeks in the control group always an infection could be observed, and germs could be cultivated.

A radiological and histological analysis of fracture healing using prebending of compression plates.

The use of an exactly contoured compression plate to the surface of a bone will lead to asymmetrical loading of that fracture line with possible gapping of bone opposite the plate. The stability of fixation can be increased through the use of compression combined with prebending. The present study in 19 sheep demonstrates the biological effects of 3 modes of plating fixation: (1) no compression; (2) compression; and (3) compression after prebending using 2 types of compression plates with different stiffness evaluated radiographically and histologically.

Physical and biological aspects of fracture healing with special reference to internal fixation.

Fracture healing is a repair process of a mechanical discontinuity loss of force transmission, and pathological mobility of bone. Through a sequence of changes of tissue development and geometry, the original structural integrity is restored. The recovery of rigidity and strength is related to tissue differentiation.

[Effect of so-called electrodynamic potentials on experimental reactive pseudoarthroses in animal experiments].

Eelctromagnetic and a.c.-stimulation according to the method of Kraus was investigated using experimental hypertrophic delayed unions of the radius in beagles.

Behavior of cortical bone grafts under different types of fixation.

The fate of cortical bone grafts, rigidly fixed by means of a special metal splint, was studied in rabbits. Cortical grafts of fresh autologous bone were compared with dry-stored allogenous transplants frozen to -20 degrees C. To study the incorporation and remodeling, fluorochrome labeling and microradiography were used.

[The effect of so-called electrodynamic potentials on experimental reaction-poor pseudarthrosis].

The effect of the magnetic field and the alternating current according to the Kraus-Lechner model was investigated on experimental pseudarthroses in beagle dogs. The evaluation of 16 pseudarthroses showed no effect of the method Kraus-Lechner on healing.

[Microparticles in heart operations with extracorporal circulation (author's transl)].

Disturbances of the microcirculation during extracorporal circulation are not yet clearly understood. Many authors think that microembolism is reposible. In two groups of patients with different perfusion techniques we were looking for microparticles with a new constant pressure filtration method using the Agglometer r apparatus.

[Influence of magnetic fields on growth and regeneration in organ culture].

The influence of alternating magnetic fields (30 Gauss, 20 Hz) on the growth and regeneration of embryonic rat femora in organ culture was investigated. A pure magnetic field was ineffective at a constant temperature.

[Modification of the pseudarthrosis healing process by alternating magnetic fields in vivo].

The effect of the magnetic field according to the Kraus-Lechner model was investigated on experimental pseudarthroses in beagle dogs. Double-blind evaluation of the 12 experimental pseudarthroses demonstrated that the magnetic field, applied for 3 months, had no effect on healing.