[Comparative tridimensional mechanical study of external fixation devices. Clinical deductions]. / Etude mécanique comparative tridimension de fixateurs externes. Déductions cliniques.

A tridimensional mechanical study has been carried out to compare the stabilization achievable with three types of fixators: the Ilizarov, the Orthofix and the French Army External Fixator (FESSA). The Ilizarov allows a noticeable instability persisting in every spatial plane with the exception of transverse movements. Cumbersome and unstable, this device does not seem suitable for the treatment of open fractures especially in adults. The Orthofix and the FESSA are both stable fixators. However, in compression the Orthofix tends to be transversally unstable. For diaphyseal fractures the Orthofix allows the final reduction to take place after the setting of the fixator, which is not possible with the single tube of the FESSA. Nevertheless, for epiphyseal fractures the FESSA allows many more possibilities for fixation of the fragments in every spatial plane. Both the Orthofix and the FESSA allow an axial mobilization and dynamisation; but the FESSA is the only one that allows a multidirectional dynamisation.

[Carpal instability. Diagnostic considerations and clinical study]. / Instabilité du carpe. Circonstances de diagnostic et étude clinique.

The clinical picture of carpal deviations is far from evocative and diagnosis is uniquely radiographic. Clinical features become reliable when intermittent malalignment of the carpal articulations leads to instability: the trick wrist is an example. The measurement of the radiolunar angle on a neutral position lateral view of the wrist is sufficient in the screening for carpal instabilities. A dorsal radiolunar angle of over 25 degrees or a palmar radiolunar angle of over 10 degrees may be considered to be pathologic.

[A comparative mechanical study of types of external fixator (author's transl)]. / Etude mécanique comparative de fixateurs externes. Le modèle du Service de Santé des Armées.

The authors have designed and original type of external fixator which can be used in the forces in case of armed conflict. Study has been directed towards a simple, strong and inexpensive apparatus which can be applied in emergency circumstances. Secondarily it can be replaced by another apparatus to allow compression, distraction or better reduction of a fracture without removal of the pins. The fixator should be applied as close as possible to bone and there should be three pins in each fragment, one close to the fracture, one distant and one intermediate. The best methods for the insertion of the pins have been tested.

[Osteosynthesis by adherent plates. An experimental physical study]. / Ostéosynthéses par plaques adhérentes. Etude physique expérimentale.

The creation of ridges of the deep surface of plates used for osteosynthesis increases their adherence to bone. By increasing the coefficient of friction between the plate and the bone, the stresses taken by the screws can be diminished by a third. The procedures diminishes by the same amount the risk of stripping or loosening of screws and thus the risk of pseudarthrosis. Experimental study has been made by measurement with the aid of an elliptometer and modifications in the state of polarization of a Lawer beam under the influence of shearing strains. The strains were those imposed on screws in Araldite fixing a plate whose inferior surface was smooth on one end and ridged on the other. The ridges should not be such as to prevent the later removal of the plate. Screws should be applied for preference with a dynamometric screwdriver because the stress relief is maximal with a tightening force of 12 inch pounds.

[Approaches to the semilunar bone and their indications]. / Les voies d'abord du semi-lunaire et leurs indications

The authors review incisions for exposure of the lunate bone and describe them in detail. They study the advantages and disadvantages of each approach, then consider their indications in peri-lunar luxation, scapholunar luxation and Kienboeck's disease. They emphasize the interest of the palmar routes in all cases, except for scapho-lunar luxation.