Field of the invention

The present invention relates to a device for maxillofacial surgery, in particular a device for the fixation of mandibular condyle fractures.

Background art

Mandibular condyle fractures are very common, as they represent at least 30% of all mandibular fractures. This is due to the fact that the condylar neck is the least resistant area in the entire mandible. The treatment of this type of fracture is focused on fracture reduction and rigid fixation systems to allow for osteosynthesis healing. Such a treatment can be carried out by maxiHomandibular fixation or by internal fixation or with both of these techniques. There is a heated debate among international experts on different surgery methods. Currently, one of the favorite techniques concerns an open reduction surgery with internal fixation by means of titanium mini-plates. This technique allows the mandibular function to be restored in a relatively short time. However, such an approach also has significant drawbacks such as facial nerve and soft tissue damage, due to the need for extensive subperiosteal detachments. The cases reported for this methodology show an incidence of facial nerve injury of 27%. Another technique of fracture repair contemplates the possibility of positioning the mini-plates intraorally by means of endoscopy. Whilst this methodology preserves the soft tissues and decreases the incidence of any injuries to the facial nerve, on the other hand it is characterized by increased surgical times. Moreover, the technique has a fairly long learning curve and requires dedicated instruments, with the related costs. It should also be noted that the internal fixation technique has the drawback that the position of the condyle cannot be changed once the surgery has finished and that the removal of the plates, sometimes necessary, needs further surgery in general anesthesia with the same risks as the previous one. If the condyle is fixed in an incorrect position using mini-plates and screws, morphological alterations may occur with the risk of dysfunctional problems and the onset of osteoarthritis. In these cases, the condyle position cannot be modified but with another surgery. The need to develop a surgical methodology for mandibular condyle fractures which reduces the above drawbacks is thus felt. Summary of the invention

It is the primary object of the present invention to provide a device for the fixation of mandibular condyle fractures which is easy to be used, is less invasive than the prior art, and if necessary allows the condyle position to be modified even after the surgery. The present invention thus aims to achieve the above-discussed objects by implementing a device for the fixation of bone fractures, particularly for mandibular condyle fractures which, according to claim 1 , comprises two pairs of screws, two support units for said pairs of screws to keep them reciprocally parallel and spaced apart, two connection units provided with articulation for said support units, two backing units for said connection units, a joining bar to which said backing units are hooked. The device advantageously comprises self- threading and self-piercing screws. The device components are advantageously made of stainless steel. Another object of the present invention relates to the method for treating mandibular condyle fractures comprising, in this order and according to claim 6, the following steps: preauricular incision with exposure of the condylar head, positioning and insertion of a screw with self-threading and self- piercing tip on the condylar head, correct repositioning of the condyle, insertion of a second screw with self-threading and self-piercing tip on the condylar head, positioning and insertion of another pair of screws with self-threading and self- piercing tip on the mandibular body, check of the correct realignment of the fracture, and consolidation of the system by means of a joining bar connected to the screws by means of clamps.

The dependent claims describe preferred embodiments of the invention.

Brief description of the drawings

Further features and advantages of the invention will become more apparent from the detailed description of a preferred, but not exclusive, embodiment of a device and a method for treating mandibular condyle fractures, shown by way of a non- limiting example with the aid of the accompanying drawings, in which:

Fig. 1 shows a device according to the invention;

Fig. 2 shows a screw with self-threading and self-piercing tip;

Fig. 3 shows a special screwdriver for screws and clamps;

Fig. 4 shows a support for a pair of screws. Detailed description of a preferred embodiment of the invention

With reference to figure 1 , a first embodiment of an external rigid fixation device, globally indicated with reference numeral 100, is shown. The device object of the present invention comprises two pairs of screws 1 with self-threading and self- piercing tip, two support units (4) for said screws 1 connected by means of an articulation 5 and by means of a rod 6 which may be straight or S-shaped, or even directly 7 depending on the cases, to a joining bar 8. Two backing units 9 are used to hook rod 6, or directly to hook the two support units (4) by means of clamps to the joining bar 8. The two backing units (9) can slide and be fixed by means of clamps along the joining bar 8. Fig. 2 describes a screw 1 with the detail of the self-threading and self-piercing tip 3. This type of screws facilitates the positioning and insertion thereof into the bone, which can otherwise be quite laborious and difficult especially for condylar neck fractures. These screws 1 are implanted on the bone by means of a dedicated screwdriver shown in Fig. 3. Screwdriver 10 comprises a hollow polygonal head with which it is possible to both engage and tighten the clamping nut of the clamps which is hollow inside, having a polygonal inner surface that mates with the polygonal head of screwdriver 6, and tighten screws 1 in the bone, which screws 1 are provided with a dedicated end part 2 (fig. 2) which can be engaged by the hollow head of screwdriver 10. The surgical access required for a correct positioning of the device is of the mini-invasive preauricular type. Such an access point provides access to the condylar head. The system then includes the positioning and screwing, using the dedicated screwdriver 10, of one of screws 1 of the pair on the condyle head. By this operation it is thus possible to correctly reposition the condylar fragment. Once this operation has finished, the second screw 1 of the pair, parallel to the first one, is positioned and screwed onto the condyle head by means of screwdriver 0 and a special template for parallel drilling. The two screws 1 of the pair are held in place by a support and connection unit shown in Fig. 4 and globally indicated with reference numeral 200. Such a support and connection unit consists of a connection rod 6 connected by means of an articulation to support 4, which support holds the pair of screws 1 reciprocally parallel and at a predefined distance through dedicated housings 13. Screws 1 can slide along their longitudinal axis and can thus be fixed in the correct position and locked with clamp 13 by means of the clamping nut 14 and screwdriver 10. The end part 15 of the connection rod 6 is engaged by the backing unit 9 and then fixed to the joining bar 8 (fig. 1 ). Depending on the cases, rod 6 may be S-shaped or support 4 may be directly connected to the backing unit 9 by means of an articulation. The surgical procedure then continues with the positioning and implantation of the second pair of screws on the mandibular bone. The above-described supports 200 for screws 1 are then attached to screws 1. Once the correct realignment of the fractures has been checked, the system is consolidated by the joining bar 8 which connects to the support 200 of screws 1 by means of clamps. The device used to connect screws 1 to the joining bar 8 is provided with articulation points so that the two pairs of screws 1 can orientate independently according to three orthogonal axes. Since this fixation system is totally external, with the exception of the implanted screws 1 , it allows the condyle position to be changed even after the surgery, which is not possible with an internal fixation system. Another advantage results from the special type of screws used which strongly reduces the surgery time. The technical advantage of this system thus derives from the speed of execution of the surgical procedure and its flexibility which allows post-surgery adjustments of the condyle position. In terms of costs for the health-care system, applying such a method allows a considerable saving in terms of duration of surgery, hospitalization and rehabilitation sessions. The learning curve for such a technique is considerably shorter than the above-described techniques, and moreover the risk of permanent damage to soft tissues, including facial nerve injury, is around 1%.