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Biomedical subjects

J Cordey

Publications and source records attributed to J Cordey.

71 records · Page 4Linked to original sources
PubMed1983

Rigidity of pure lag-screw fixation as a function of screw inclination in an in vitro spiral osteotomy.

The rigidity of lag-screw fixation of experimental tibial fractures was tested in 27 anatomic specimens. Spiral osteotomies with a 60 degree angle of ascent were produced using a Gigli saw. Three screws with an axial force of 100 kp were inserted at 90 degree, 80 degree, or 70 degree of longitudinal inclination. The 70 degree group was stable in axial compression up to 88 kp and the 80 degree group up to 151 kp. Rigidity in bending was 50% in the 70 degree and 80 degree groups and 27% in the 90 degree group, while rigidity in torsion was 20% as compared with the intact bone. Screws tightened with 50 kp and 150 kp showed increased rigidity as axial screw force increased. There were only small gains in torsion and bending, whereas there was a 200% gain in compression. This confirms the view that in long spiral fractures of the tibia three lag screws alone can maintain sufficient stability to permit early limb mobility. If the screws are inserted perpendicular to the bone, the high resistance to axial compression may permit early partial weight-bearing.

Biomechanical Phenomena↗
PubMed1979

[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. 7-hole dynamic compression plates (DCP) and 4.5 mm cortex screws were used to stabilize transverse osteotomies in human tibiae in vitro. Flexural and torsional testing revealed that the use of an inclined lag screw or a prebent plate increases stability compared to the one achieved with an exactly contoured plate alone. Preliminary tests suggest, that a combination of plate lag-screw and prebending offers stability up to high loads.

Biomechanical Phenomena↗
PubMed1979

[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. Thus it could be determined at what level of screw compression and at what tangential load of the related surface bone-plate, gliding occurred. The coefficient of friction was found to be 0.2 +/- 0.09 (x +/- Sx). It can be concluded that in vivo friction produced at the plate-bone contact surface is able to guarantee stability of fixation.

Animals↗
PubMed1979

[Registration of fibular movements in vivo in relation to the tibia at the level of the ankle joint].

Fibular movements in relation to the tibia are known on extension and dorsiflexion of the ankle-joint and have been proved by experiences on cadaveric preparates using outstanding points of relation. To registrate fibular movements in vivo a special trigonometric system has been developed permitting calculation of definite movement in frontal and sagittal plane as well as a rotation around axis. Twelve healthy volunteers were examined in this way during extension and dorsiflexion of the ankle, with and without weight-bearing. The results showed that we should not consider isolated fibular movement but analyse simultaneous complexity of movements in a graphic comparison. Under these conditions we observe a very high significance of fibular movements depending each of other. The emphasis can be designed in a field covering all the points reached by fibular movement in frontal and sagittal plane of the twelve healthy volunteers during movement of the ankle; it shows that the fibula functions like a guide-stick for ankle movement. Reflecting on the designed fields of healthy persons, some patients with posttraumatic pathological alterations of the ankle-joint have been analysed.

Ankle Injuries↗
PubMed1975

[Quantitative determination of tissue tolerance to corrosion products in organ culture].

The tissue tolerance for metal was investigated using an organ culture of embryonic rat femora. We found reproducible results using a standardized experimental method. A good correlation between the applied concentrations and resulting growth inhibition occurred and dose-response curves were established. The experimental model is applicable for testing tissue tolerance for the soluble products.

Animals↗
PubMedDate not supplied

Biomechanical evaluation of the less invasive stabilization system for the internal fixation of distal femur fractures.

OBJECTIVE: Comparison between a Less Invasive Stabilization System (LISS) using monocortical screws with angular stability and two conventional plate systems Condylar Buttress Plate (CBP) and Dynamic Condylar Screw (DCS) for the treatment of distal femoral fractures with respect to biomechanical properties. DESIGN: Biomechanical study using paired cadaver femurs. In Test Configuration 1 (distal test), a ten-millimeter gap at the diaphysis-metaphysis junction simulates a supracondylar femoral fracture. Test Configuration 2 (proximal test) has the same configuration, but the gap was cut in the isthmic region. Proximal and distal plate ends were fixed to corresponding cortical bone fragments in both tests. Optical displacement transducers served to quantify the system's ability to withstand a stepwise increased load. Reversible (deflection) and irreversible deformation (subsidence) of the bone-plate construct was investigated. RESULTS: In Test Configuration 1, LISS showed less irreversible deformation in 72 percent of the left-right comparisons. No correlation between bone mineral density, cross-section area of bones and the measured response of the construct under load was found between pairs. In Test Configuration 2, 83 percent of the left-right comparisons showed less permanent deformation but a higher elastic deformation for LISS. CONCLUSIONS: These results suggest an enhanced ability to withstand high loads when using the monocortical screw fixation technique with angular stability. A higher elastic deformation of LISS compared with conventional plating systems in distal femoral fractures can be explained by the lower bending stiffness caused by different design and material properties.

Biomechanical Phenomena↗