The present invention relates to an internal saw for osteotomy of tubular bones, comprising a base body provided with a saw blade which can be moved radially out of the base body.
An internal saw of this kind for tubular bones is known from German utility model G 92 17 188.5, for example. With an internal saw of this kind, a tubular bone can be cut through with a saw and a saw unit. The saw emerges radially from the base body and cuts through the bone as the base body is turned. Particularly in surgery, bones have to be cut through radially, for example, if bone or bone fractures do not fuse correctly or if it is necessary to correct malformed or curved bones or extremities which are too long or too short. Internal saws of this kind are usually guided into the tubular bone from the end in order to cut through the bone from the inside outward. Particularly in distraction of bones, a medullary nail, a distraction device or the like is inserted into the axial bore or into an axial access after the tubular bone has been cut through.
A disadvantage of the conventional known internal saw is that it is awkward to operate and difficult to insert and control. In particular, when the above-described internal saws are used, the periosteum and surrounding tissue are often damaged when cutting through the tubular bone, which is undesirable. This slows down the course of healing.
U.S. Pat. No. 5,591,107 describes an oscillating internal saw for osteotomy of tubular bones, where a manually operated lever is used to influence an advance movement of the radial saw, which emerges radially from a base body. In addition, this manually operated lever can be used to effect a rotation movement.
WO 01/34040 A1 discloses an internal saw for cutting through tubular bones, where two tools mounted like scissors are moved apart from one another by means of centrifugal force during rotation, these tools bearing internally on the tubular bone and thus cutting through the tubular bone upon rotation. A disadvantage here is that this device can only be used to cut through bones of large internal diameter.
It is an object of the present invention to make available an internal saw of the type mentioned at the outset which eliminates the above-mentioned disadvantages and with which it is also possible to exert an influence on different bone cross sections, so that these are cut though uniformly. Such an internal saw should also be easy to operate and inexpensive to produce.
The foregoing object is achieved by the present invention wherein a saw blade can be very easily exchanged and advanced. For example, an operating element can be assigned to a jacket surface of the base body, which operating element can be operated by means of a finger of a human hand and can be axially displaced. The saw blade, which directly adjoins the operating element, can be pushed radially out from one end of the base body in a graduated manner, using the fingers of a human hand, in order to advance or orient the saw blade. At the same time, the base body can be turned radially about a center axis in order to perform a sawing operation. It is important, however, that, during the radial turning of the base body, the latter, and thus also the saw blade, performs an oscillating movement by way of a drive device. This oscillating movement improves the cutting action and at the same time ensures that saw blades can be used which in principle do not damage the periosteum or the bone itself. The saw blade obtains its cutting and separating action through the oscillating movement alone, but only for hard objects, such as for example the tubular bone. When cutting through the tubular bone, by radial advance of the saw blade and simultaneous oscillation, the saw blade abuts the periosteum but does not damage it in the process.
A further advantage of the present invention is that the advance of the saw blade can be graduated manually, with or without locking, so that the surgeon can read off how deep he has cut through the tubular bone. This advance movement can also be prestressed by means of a spring element which engages on the operating element or directly on the saw blade. The invention is not intended to be limited to this.
In a further illustrative embodiment of the present invention, it has proven particularly advantageous to operate the saw blade, in particular the operating element, by means of an actuator, if appropriate of a control means attached to it, a force sensor being provided between actuator and saw blade or between actuator and operating device. The control means is able to provide the actuator, for example, with an input corresponding exactly to CAD/CT cross-sectional data of the bone, which then correspondingly controls the depth of advance or a return movement of the saw blade depending on the radial angular position with respect to the bone.
By this means, a bone which does not have a circular cross section can also be sawn through uniformly since the advance of the saw blade takes place according to the cutting data and the cross-sectional profile of the bone. A computer-aided control means can provide for an advance depth of the saw blade according to the cutting data or cross-sectional profile of the tubular bone. This is also intended to lie within the scope of the present invention.
It has also proven particularly advantageous that a drive device at the same time transmits, via an oscillation gear, a radial oscillating movement to the base body, in particular to the saw blade, and at the same time can perform a radial complete rotation in a selectable direction for radially cutting through the bone.
Further advantages, features and details of the invention will become clear from the following description of preferred illustrative embodiments and from the drawing, in which:
a shows a diagrammatic partial longitudinal section through an internal saw for osteotomy of tubular bones;
b shows a diagrammatic partial longitudinal section through a further illustrative embodiment of an internal saw according to
c shows a diagrammatic partial longitudinal section through a further illustrative embodiment of an internal saw according to
According to
By movement of the operating element 9 in the double arrow direction X shown, the end area of the saw blade 5 is moved radially into or out of the base body 1 in the double arrow direction Y shown.
As can further be seen from
It is further of advantage that the saw blade 5, for example in the case of single use, is simply withdrawn from the insertion shaft 8 and can be very easily exchanged. If appropriate, the operating element 9, with fixed saw blade 5, can be inserted again into the base body 1 through the insertion shaft 8 for renewed use. The invention is not limited to this.
It is important, however, that at one end of the base body 1 the grip eIement 6 is radically and rotationally uncoupled with respect to the base body 1 so that the grip element 6 can, for example, be held by fingers of a human hand, so that the base body 1 can be driven manually and/or automatically about a center axis M. At the other end of the grip element 6, an attachment 12 is provided, preferably as an AO attachment, for receiving a drive device 13, as is shown, for example, in a simplified form in
The drive device 13 can also simply be a manual grip with which the base body 1 can be moved in a rotation movement about the center axis M, the grip element 6 being uncoupled from the rotation movement about the center axis M.
In the area of the outlet opening 4, the saw blade 5 lies on an axis A which, in the present case, encloses an angle W, preferably of 90°, between the center axis M.
The outlet opening 4 is oriented in the base body 1 at an angle W of 90° with respect to the center axis M. It has proven advantageous to provide the outlet opening 4 in the base body 1 at a smaller angle of between 40° and 90°, for example. In this way, the bones can be cut through in inclined cutting surfaces, which results in an enlargement of the cutting surfaces. Thus, in the case of quite large cutting surfaces, it is also of advantage here that more rapid healing is provided and, in particular, greater stability upon fusion of a large cutting surface.
The outlet opening 4 can be oriented at an angle W of, for example, 40° to 140° between axis A and center axis M. Changing the angle W even during operation, for example by means of a device not shown here, is also intended to lie within the scope of the present invention.
It has also proven advantageous to have a flushing channel 23 which opens into the insertion shaft 8 and which can serve for flushing and/or aspiration. The base body 1 can also be cooled at the interface via the flushing channel 23.
It is also conceivable for the operating element 9 and also the graduation 11 to be provided all round the base body 1, so that the operating element 9 can be gripped in any desired position and the graduation 11 can be read off in any desired position. In this case, the graduation 11 is arranged all the way round the jacket surface 7 and can, if appropriate, include a plurality of different graduations 11. The operating element 9 would then also be designed as an annular sleeve or the like which engages completely or at least partially around the jacket surface 7 of the base body 1.
In a further illustrative embodiment of the present invention according to
The difference is that the guide 2 forms a greater radius for leading the saw blade 5 from the outlet opening 4 to the insertion shaft 8. If appropriate, a groove can be formed in the base body 1 in the area of the insertion shaft 8 in the jacket surface 7, in order to guide or accommodate the saw blade therein.
In the manner described above, the saw blade 5 can be moved to and fro via the operating element 9 along the graduation 11 in the direction shown by the double arrow X, in order to move the saw blade 5, in particular its saw teeth 10, out of the outlet opening 4.
It is also conceivable, here, to move the operating element 9 with locking relative to the graduation 11.
The scope of the present invention is also intended to include the operating element 9 being adjoined by a spring element 14, which is designed as a compression and/or tension spring, in order to prestress the operating element 9 toward the head area 3. It is also conceivable to alter the spring constantly and to vary the prestressing force of the spring element 14.
In a further illustrative embodiment of the present invention according to
A force sensor 17 can be provided between actuator 15 and operating device 9 and/or between actuator 15 and saw blade 5, in order to exactly measure a permanent force, in particular an advance force. This is important, for example, if the saw teeth 10 cut completely through a tubular bone 18, see
It has also proven advantageous that, via the control means 16, the actuator 15 is able to adapt an advance movement of the saw blade, as it is shown in particular in
In the illustrative embodiment according to
An important aspect of the present invention is that the depth of advance of the saw blade 5, in particular in the area of the outlet opening 4, is different depending on the position and cross section of the bone, since the tubular bone 18 is thicker or thinner at different angle areas and has different radii with respect to the center axis. In order to compensate for this, a depth of advance can be permanently varied on rotation of the internal saw R1. Preferably, the advance of the saw blade 5 is controlled automatically in accordance with the cross section of the tubular bone 18.
An important aspect of the present invention is, however, as is shown in particular in
Another important aspect of the present invention is that the base body 1, as is shown in particular in
Number | Date | Country | Kind |
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101 55 739.6 | Nov 2001 | DE | national |
101 60 232.4 | Dec 2001 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP02/09048 | 8/13/2002 | WO |