Surgery – Instruments – Orthopedic instrumentation
Reexamination Certificate
2000-01-11
2001-05-22
Hirsch, Paul J. (Department: 3732)
Surgery
Instruments
Orthopedic instrumentation
Reexamination Certificate
active
06235032
ABSTRACT:
The invention relates to a bone plate for treating fractures of the calcaneal bone.
The complicated physical arrangement of the articular surfaces of the calcaneal bone makes it difficult to reposition these surfaces accurately following fractures. Persistent problems are relatively common (ZWIPP: Der intraartikuläre subthalamische Fersenbeinbruch [The intraarticular subthalamic fracture of the calcaneal bone], Operat. Orthopädie Traumatologie 7 (1995) 237 et seq.). To stabilize the repositioned fragments, use is mainly made of H-shaped and T-shaped plates which are flat and, if appropriate, are bent to shape in order to adapt to the physical surface shape of the bone (FR-A-2622431). This not only demands considerable manual dexterity but also requires that the operating surgeon has a detailed picture of the surface shape of the affected bone, although such a detailed picture can be obtained only with difficulty on account of the presence of the fragmented bone. Also, the available contours of the H-plates and T-plates in many cases fail to provide an adequate adaptation to the fracture pattern. An unsuitable choice or configuration of the plates in terms of their contour and their physical shape can therefore easily lead to incorrect results, which go unnoticed. It can also happen that insufficient healing is obtained as a result of the fracture gaps being too large.
The invention is based on the object of minimizing the aforementioned disadvantages. The solution according to the invention lies in the features of claim
1
and preferably those of the subclaims.
Although the calcaneal bone fractures which occur display a very wide variety (ZWIPP loc. cit.), certain typical fracture patterns can nevertheless be distinguished. The invention makes available a bone plate which is suitable for a common fracture pattern.
The bone plate according to the invention which is to be arranged laterally, and is particularly suited for so-called tongue fractures, has a longitudinal part with an approximately central arch, a transverse part projecting in both directions from the posterior end of the longitudinal part, and a first projection projecting downwards from the anterior end of the longitudinal part, and a second projection projecting cranially near this other end, and offset in relation to the first projection. The two projections are angled or arched in relation to one another (if appropriate including the longitudinal part) about an axis running approximately parallel to the longitudinal part, so that the longitudinal part located between them experiences an arching, and in particular the first projection is drawn inwards (for terminology see ZWIPP loc. cit. p 238). In tongue fractures, the transverse part located at the posterior end of the longitudinal part is suitable for drawing together the posterior facet fragment and the tuberous fragment located below this. The first projection can grip round the neck of the calcaneal bone in order to hold the anterior process, while the second projection below the posterior facet positions the posterior facet fragment or a further fragment located at this point.
The adaptation to physical surface shape of the bone concerns its lateral face between the calcaneal tuberosity and the anterior process. By means of the adaptation of the plate shape to the average surface configuration of the bone, it is possible, even when the individual bone shows certain deviations from the average shape, to exclude a grossly incorrect positioning of the fragments caused by the shape of the bone plate. In addition, in extreme cases, the operating surgeon is easily able to model the plate slightly, there being no . . . risk of gross mis-shaping because his corrections can be limited to slight changes of shape. The compressing effect of a number of screw bores ensures that the fragments are drawn together without gaps. This is known per se (DE-U-9217769).
When the compression bores at the ends of the transverse part are oriented towards one another, the posterior fragment and the tuberous facet fragment are drawn towards one another. If, on the second projection, there is a compression screw bore directed towards the longitudinal part, then the anterior area in particular of the posterior facet fragment is drawn towards the tuberous fragment. If the first projection has a compression screw bore directed towards the longitudinal part and to the transverse part, then the sustentacular fragment is drawn towards the two other said fragments.
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Hirsch Paul J.
Morrison & Foerster / LLP
Waldemar Link (GmbH & Co)
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