The invention relates to a screwdriver handle for a torque limiter according to the precharacterizing clause of Claim 1 and a system according to the precharacterizing clause of Claim 7.

During plate osteosyntheses, various types of screws are used. For some of them, the use of a torque limiter is prescribed or at least desired.

The prior art discloses several torque-limiting apparatuses, not only in the medical sector. In general, they comprise a one-part device which can be used only for the corresponding purpose. The field of use is consequently very limited. Furthermore, many of these are not suitable for medical applications. Such apparatuses are disclosed, for example, in DE-A1-38 08 238 and US-B 1 - 4,774,864.

The prior art furthermore describes apparatuses in which a screwdriver insert having a fast-action coupling is combined with a separate torque limiter and a separate handle. Combinations of different torque limiters, screwdriver inserts and handles are possible thereby. The publications US-B 1-6,640,674; US-B2-6,358,152 and EP-A1-1 110512 disclose, for example, such devices. However, a disadvantage is that the mass distribution is very unfavourable. The main weight is present not in the hand but in the region of the torque limiter since this is much heavier than the handle. This complicates the handling of the device since the surgeon always has to take this mass distribution into account. In the case of an uncontrolled movement or of an external effect, the apparatus tends to fall out of the hand, which can have serious consequences for the patients. Furthermore, the operation time is increased since the now nonsterile tool has to be replaced. It is therefore an object of the present invention to improve the above-mentioned apparatuses. It is intended to provide a screwdriver with torque limitation which is easy to handle. It should furthermore be capable of being safely guided. Moreover, there should be a high degree of variability with respect to different torque limiters or screwdriver inserts.

These and other objects are achieved, according to the invention, by a screwdriver handle for torque limiters according to Claim 1 and a system according to Claim 7. Advantageous developments are to be found in the dependent Claims.

The screwdriver handle according to the invention for torque limiters is intended for medical applications. The screwdriver handle has substantially the shape of a hollow cylinder which is open at least at the front end, the internal diameter being slightly greater than the external diameter of the torque limiter so that the torque limiter can be substantially completely held in the screwdriver handle and can be locked therein.

The screwdriver handle according to the invention differs from known apparatuses in particular through good handling properties and a changeable shank. Consequently, the achievement according to the invention provides an apparatus which can be easily and safely handled and by means of which screws can be screwed in and unscrewed with torque limitation. The centre of gravity of the assembled apparatus comprising screwdriver handle, torque limiter and screwdriver insert with blades is thus in the hand.

Another advantage is that the corresponding screwdriver inserts can be easily changed. It is therefore possible to change between different screw types without problems. The screwdriver handle is furthermore adapted to known torque limiters and screwdriver inserts and is compatible with them so that existing systems can be used and the surgeon can assemble all desired arrangements from a basic equipment set. Costs are reduced thereby.

It is preferably furthermore envisaged that the screwdriver handle will have a transverse hole for receiving a transverse bolt. This transverse bolt can cooperate with a set of different torque limiters and/or different surgical tools.

The screwdriver handle is preferably formed from a sterilizable and/or autoclavable material. This makes it capable of being used several times.

When the screwdriver handle is assembled with the torque limiter and shank ready for use, the level of the torque limitation should be visible. This is necessary for avoiding the application of a torque which is too high or too low, with the result that the screws would be tightened too tightly or insufficiently. Insufficiently tightened screws can later become loose, necessitating a further operation. If, on the other hand, the screws have been tightened too tight, problems arise during extraction of the screws. Visualization of the level of the torque limitation can be effected, for example, if the handle is inscribed or can be inscribed with torque limits and/or type of torque limiters which can be used, for example the article numbers thereof.

A system which comprises the screwdriver handle according to the invention, which can be coupled to the machine-rotatable torque limiter, is furthermore proposed. The system can be used for medical applications. Furthermore, the torque limiter preferably has a fast-action coupling so that different screwdriver blades can be used.

The list of reference numerals and the drawings, together with the objects described or protected in the claims, are an integral part of the disclosure of this Application. The interior structure of the torque limiter is unimportant in the context of the invention. Preferably, a conventional torque limiter can be used.

Description of figures

The invention can be even better understood by reference to the attached exemplary figures. They are described in relation to one another and as a whole. Identical reference numerals denote identical components, and indices indicate components performing the same function.

Fig. 1 shows a perspective view of a screwdriver handle according to the invention;

Fig. 2 shows a plan view of the screwdriver handle of Fig. 1 with a torque limiter prior to assembly; and

Fig. 3 shows the plan view of Fig. 2 after assembly.

Fig. 1 shows a perspective diagram of a screwdriver handle 1. As is evident from the diagram, this is a substantially cylindrical hollow body. The screwdriver handle 1 has a first end 2 and a second end 3. The second end 3 has an opening 5. The first end 2 may be closed or likewise at least partly open.

Recess grips 4 are preferably provided on the surface 7 of the screwdriver handle 1. This makes it easier for the surgeon to grip the handle and reduces the danger of slipping. Furthermore, at least one release knob 6 is present. This can be used for releasing a torque limiter arranged in the screwdriver handle from said handle again.

The diagrams of Fig. 2 and 3 show the arrangement of screwdriver handle 1 and torque limiter 10. The screwdriver handle 1 is pushed over the torque limiter 10 for connection of said handle, as indicated by the arrow 15, or, conversely, the torque limiter 10 is inserted into the screwdriver handle 1 via the opening 5. The major part of the torque limiter 10 is held by the screwdriver handle 1 , as is clear from the diagram of Fig. 3.

The torque limiter 10 is locked h the screwdriver handle 1. This locking is preferably effected by snapping in and subsequent locking of the torque limiter 10 in the screwdriver handle 1. The lock can be released again with the aid of the release knob 6.

The torque limiter 10 is preferably machine-rotatable. Consequently, it can, for example, also be connected to electrical screwing devices via the shank 11. The screwdriver handle 1 is therefore advantageously designed so that it can be coupled to torque limiters 10 which can also be actuated by means of other screwdrivers, in particular electrical ones. The torque limiter 10 furthermore preferably has a fast-action coupling system so that many different screwdriver blades can be used. The torque limiter 10 is consequently one which can be universally used.

Fig. 2 and 3 furthermore clearly show the ratio of internal diameter I of the screwdriver handle 1 to external diameter A of the torque limiter 10. The internal diameter I is somewhat greater than the external diameter A. This makes it possible in the first place to introduce the torque limiter 10 into the screwdriver handle 1. The internal diameter I is, however, preferably only slightly greater than the external diameter A. In general, the torque transmission takes place via the shank 11. However, it is also possible to form an interlocking connection between torque limiter 10 and screwdriver handle 1. For this purpose, the geometry of the torque limiter 10 and screwdriver handle 1 is correspondingly designed and/or said parts have surface structures which permit an interlocking connection. This interlocking connection can then serve for torque transmission between torque limiter 10 and screwdriver handle 1. List of reference numerals

1 - Screwdπver handle 2- First end 3- Second end A- Recessed grip 5- Opening 6- Release knob 10- Torque limiter 11 - Shank 12- Receptacle 15- Arrow