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Biomedical subjects

M Borgeaud

Publications and source records attributed to M Borgeaud.

8 recordsLinked to original sources
PubMed2001

[Treatment of diaphyseal pseudarthrosis by circular external fixator].

The aim of this retrospective study was to evaluate the effectiveness of circular external fixator according with Ilisarov technique for the treatment of diaphyseal pseudarthrosis. The union rate obtained in our serie was 91%. We assessed the complications related to surgery and analysed the reasons for failed technique. Between january 1986 and february 1996, 23 patients were included in this study with a mean follow-up of 65 months. The period of external fixation was 209 days on average. 21 patients had united fractures. The failures were attributed to inadequate interfragmentary contact. The main problem during treatment was pin tract infection. The late complications included axial deformities, re-fractures and joint stiffness. Circular external fixator proved to be useful for the treatment of diaphyseal pseudarthrosis, particularly those complicated by infection or post-traumatic shortening.

Adolescent↗
PubMed2000

Force transfer between the plate and the bone: relative importance of the bending stiffness of the screws friction between plate and bone.

Stability in plate fixation of fractures relates to the motionless fastening between plate and bone. When the plate is affixed to the bone, high shear force may appear between plate and bone, particularly near the end screws, which can lead to motion under weight-bearing. Two mechanisms might be involved in the prevention of motion: the bending stiffness of the screws or the friction between the screw and the plate. Experiments performed in vivo and in vitro show that with conventional plates, motion is prevented by friction and depends upon the axial force of the screw, pressing the plate onto the bone. The torque applied to the screws is crucial. Motion appears under smooth plates under relatively low physiological loads. With newly developed internal fixators, the motion is prevented by the structural stiffness of the plate-screw system.

Animals↗
PubMed2000

Mechanical analysis of the bone to plate interface of the LC-DCP and of the PC-FIX on human femora.

The scope of this analysis was to evaluate the mechanical behaviour of newly developed plates at the junction between plate and bone (friction between plate and bone) for the limited contact dynamic compression plate (LC-DCP) and the point contact fixator (PC-Fix) under simulated physiological load and using the tension band principle on the human femur. The intact human cadaveric femora were plated on the lateral aspect according to the tension band principle (AO) and subjected to a load which simulated careful physiological load in single stance. Five strain gauges were glued around the bones, parallel to the bone axis, at five levels, whereby three of them had to be covered by a bone plate and the two others were just outside the plate location. The cross-sectional geometry had been obtained at these levels using computed tomography. One side was plated using the conventional compression plate LC-DCP and the contralateral side using the internal fixator PC-Fix. The LC-DCP was affixed using screws tightened at different torque values and the PC-Fix at a standard torque value. Motion (slippage) between the plate and the bone was indicated by a hysteresis of the strain reading during loading and unloading. Slippage was more important for the LC-DCP than for the PC-Fix, particularly at the proximal end of the plate and when the screws were insufficiently tightened on the LC-DCP. As expected, better stability was obtained with the PC-Fix.

Animals↗
PubMed2000

[Metatarsalgias].

Explore the source record for details and available documents.

Biomechanical Phenomena↗
PubMed1999

Loading model for the human femur taking the tension band effect of the ilio-tibial tract into account.

A loading model permitting the application of relevant loads to the diaphysis and constructed on the basis of current knowledge of the biomechanics of the femur will be presented. This model takes into account the force acting through the ilio-tibial tract in the frontal plane and the forces acting on the condyles in the sagittal plane. There is compression on the femoral head and on the condyles and tension on the greater trochanter. Experimental verification using human cadaveric femora instrumented with strain gauges has shown that the adequate loading condition is: a line of force tangential to the femoral head a line of force tangential to the dorsal aspect of the distal junction of the diaphysis and metaphysis. Under these conditions, the calculated forces will accord well with values assessed in vivo. The model described here represents a simple procedure for experimental load application, producing realistic strain values. The proximal part of the bone is placed under tension on the dorsal aspect; the medial aspect is under compression. The strain pattern develops such that the tensile forces affect the anterior aspect distally and compression the dorsal aspect.

Femoral Fractures↗