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A biomechanical in vitro test was performed to determine the stabilizing effect of various implants for the surgical treatment of the torn acromioclavicular joint. In a specially designed testing device, plastic and cadaver specimens of the shoulder girdle were stressed in various ways. Different dislocations between the acromion and the clavicle and between the clavicle and the coracoid were determined, as well as the stiffness of the implants. A convenient stabilizing effect combined with less rigid fixation to secure the newly treated AC joint was provided by K-wire fixation with cerclage. Interfering shear and bending stresses could be avoided with this method, while the other implants showed various disadvantages. From a biomechanical point of view, a carbon-fiber ligament replacement provides sufficient stability in cases of chronic acromioclavicular separation.

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Sheep had their right metatarsals osteotomized midshaft and stabilized by plate and screws. One group was injected with 1250 units of Factor Thirteen for 9 days postoperatively, and a control group received placebo injections. After 8 weeks, the bones were evaluated biomechanically, histomorphologically and by densitometry. The bones of the treated group had a significantly higher tensile strength than the bones of the control animals. The correlation of biomechanical and morphological results demonstrated that the tensile strength increased with an increasing number of osteons crossing the osteotomy gap. The hydroxyapatite content of the bone healing zone was 7.3 per cent higher for the treated bones than for the control bones.

In an experimental study on sheep the effects of fibrin adhesive system (FAS), plasma factor XIII (FXIII), and calcitonin on autologous cancellous bone grafts were studied. Drill holes in the tibia were filled with transplant bone, either untreated or locally treated with fibrin adhesive, with or without plasma factor XIII. We used 24 sheep, divided into three groups. Plasma factor XIII and calcitonin were administered parenterally; the third group received no treatment. For evaluation we carried out quantitative bone and fluorescence morphometry and microangiography. We found that local fibrin adhesive significantly decreased the remodeling and growth of the transplanted cancellous bone. Plasma factor XIII, given parenterally, increased the amount of bone in the transplant site; calcitonin showed no visible effect.

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A number of studies in medical literature suggest that during implantation of hip prostheses pulmonary embolism of medullary contents and of air may occur. Proof of this suggestion was based on histological examination of lung tissue in animal experiments as well as on post mortem examinations of human tissue. In vivo evidence of this suspected embolism has been lacking so far, since an appropriate technique has not been available. Using transesophageal two-dimensional echocardiography, continuous imaging of the right atrium and the right ventricle can be performed in order to prove this suspected embolization in vivo. Thus, in a prospective randomized study of 26 patients undergoing hip surgery, the right atrium and right ventricle were continuously imaged. Simultaneously, the end-expiratory CO2 partial pressure was recorded. The medical literature suggests that a venting hole in the shaft of the femur prevents the rise in pressure in the medullary space and thus also averts embolism. Therefore, prior to the implantation of the shaft prosthesis, and in order to vent the medullary space, in 13 patients a 4.5-mm lateral borehole was drilled into the femoral shaft, located two finger breadths distal to the point were the end of the prosthesis would be positioned. In 12 of 13 patients in the control group without boreholes, transesophageal two-dimensional echocardiography revealed that air bubbles formed during the implantation of the shaft. In the group with boreholes, however, presence of air could be demonstrated in only four patients (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Flow E x a m i n a t i o n of 1%edon-Suction DrainageSummary. Mathematical and experimental results demonstrate that the customary Redon drain develops suction only over a very short initial distance. The disadvantage of rapidly diminishing suction is overcome in a newly developed drain in which equidistant openings of continually increasing aperture are aligned towards the drain end.