Surgery – Instruments – Orthopedic instrumentation
Patent
1988-04-21
1990-01-16
Yu, Mickey
Surgery
Instruments
Orthopedic instrumentation
128 92ZZ, 128 92ZW, A61F 504
Patent
active
048936189
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an external fixation apparatus comprising at least one flexible tube-shaped portion which is disposed externally of the patient opposite the bone fragments to be fixed and which is connected with the wires, nails or screws secured in the various bone fragments, wherein the tube-shaped portion filled with a hardenable material, after the material is hardened, forms a rigid frame with the wires, nails or screws which holds the bone fragments together in a desired position for the union of the same.
External fixation apparatuses serve for the orthopedic fixation and the holding together of bone fragments. Fractured bones are fixed in their position relative to one another with an external fixation apparatus so that the healing can take place in the correct position. For this purpose, bone nails, preferably with a thread, e.g. Schanz's screws or bridging rods, are inserted into or through the bone and, at their ends projecting from the body, interconnected by at least one rod-shaped member, e.g. a sliding rod or a guide rod. This connection is brought about with the aid of tightening means that are constructed as shims, articulation pieces and, if necessary, as ball-and-socket joints, as coupling means or as grips or the like. A frame structure can thus be formed, with the aid of which the bone fragments can be rigidly fixed and held.
Known tightening means consist of non-oxidizing steel. When the fixation apparatus is applied and the rods are tightened, the entire frame structure is relatively loose, wobbly and displaceable into itself since the rods to be reciprocally held have to be slackened in the tightening means so that they can be brought into the correct position. Hence the application of a fixation apparatus can, in the end, not be carried out by a single person, but additional assistants are needed for holding the joints and double joints as well as the frame until, subsequent to the positioning, the tightening and fixing can ultimately be carried out. In order to facilitate this work, separate tightening devices may be employed. However, since steel has a very high elasticity coefficient and a smooth surface, it is not possible to obtain only a weak clamping by tightening a clamping bolt; on account of the high elasticity coefficient, already a slight turning of a setscrew brings about a very substantial change in the gripping pressure. Consequently, when fitting the fixation apparatus, the rods, bones nails or screws can only lie loosely within the tightening means. Added hereto is the circumstance that the components and elements used for the fixation apparatus, due to their material selection, impair X-rays. Moreover, the production costs of fixation apparatuses constructed in this fashion are very high.
The utlization of metal components predominates from which the fixation apparatus is assembled by the surgeon depending on individual requirements. In order to obtain a radiotransparency with fixation apparatuses, use is also made of components fabricated from non-metallic materials. Thus, from the DE-A-27 45 504, a device for the immobilization and/or support of human or animal limbs is known which possesses connecting members that are oppositely located in pairs and accommodate at least one bone screw or one bone nail each, which, via clamping members, are connected by means of connecting rods or threaded rods. The connecting members, the clamping members and the connecting rods as well as the integrated tighteners consist in this case of fiber reinforced thermoplastics.
Furthermore, from the DE-A-31 41 909, an orthopedic fracture fixation device with at least one elongate part located externally of the patient is known, which is connected by means of fracture pins or the like that can be secured in the various fragments of the broken bone, wherein the elongate part and the pins form a rigid frame holding the fragments in the desired position for their union. The elongate part located externally of the patient, which is secured to the various fragments of the f
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De Puy Mfg. Co. Catalogue, pg. 55, 1936.
Journal of Bone and Joint Surgery, Manipulation and External Fixation of Metacarpal Fractures, vol. 63A, No. 8, 10/1981, pp. 1289-1291.
Rooney Kevin G.
Yu Mickey
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