DESCRIPTION

The present invention relates to an osteosynthesis hook plate.

This kind of plate is particularly used in the treatment of fractures of femur proximal epiphysis (or head).

The osteosynthesis is an orthopaedic technique for fracture treatment that provides for the stabilization of the bone fracture through means (for instance metallic means) that are surgically inserted into the fractured bone and that are capable of maintaining the bone immobilised until it consolidates. Among the means used in osteosynthesis, and more particularly in the treatment of fractures of long bones such as shinbone and femur, suitable shaped monolithic plates are known, that are provided with holes for fastening screws and compression screws. Such an osteosynthesis plate is disclosed for instance in patent application WO 01/91660. For fractures in the trocanther region, i.e. at the proximal epiphysis of the femur, hook plates like the plate shown in Figure 1 are known.

Plate 101 of Figure 1 includes a Hat body 103 having an elongated shape and provided with a first plurality of through-holes 105 for fastening screws 107 fastening the plate to femur 100 and with a second plurality of through-holes 109 - provided at the femur proximal epiphysis - for compression screws 1 1 1. For a correct positioning of plate 101 - and particularly of compression screws 1 1 1 - and for an appropriate reduction of the fracture, said plate 101 further includes a hook 1 13 provided with a pair of hooking elements 1 15 that engage with the trocanther of femur 100. However, osteosynthesis plates of the kind shown in Figure 1 have non-negligible drawbacks. More particularly, it is evident that it is not possible to adjust plate 101 according to the shape and size of the patient's femur and trocanther so as to fit it to the anatomical contour of the fractured bone.

As a consequence, it is necessary to manufacture a large number of plates having different shapes and sizes, so as to take into account the different bone structures of different patients. Indeed, said plates are usually marketed in kits containing a large number of items, each having different shape and size.

The main object of the present invention is to overcome the aforesaid drawback of prior art by providing an osteosynthesis hook plate capable of being adjusted so as to fit the anatomical contour of femurs having different shapes and sizes.

This and other objects are achieved by an osteosynthesis hook plate according to the invention, as claimed in the appended claims.

Thanks to the fact that according to the invention the body of the plate and the hook are separate pieces, that can assume different relative positions with respect to each other and then be rigidly fastened, the plate according to the invention can fit femurs with different shapes and sizes, having trocanthers with different shapes and sizes.

Furthermore, thanks to its modular construction, hooks with different shapes and sizes can be associated to the same body of a plate according to the invention, according to specific requirements. According to a preferred embodiment of the invention, the osteosynthesis plate further includes a plurality of modular transversal supports for inserting cortical screws into the fractured bone laterally with respect to the plate flat body.

The possibility of inserting as many of said supports and in such positions as suitable for each surgery intervention further increases the versatility of the plate according to the invention. It is evident that the osteosynthesis plate according to the invention involves considerable advantages, both technical and economical, since with a little number of parts it is possible to obtain osteosynthesis hook plates lining a large number of femurs having different shapes and sizes. Further features and advantages of the invention will be evident from the detailed description of the preferred embodiments of the invention, given by way of non-limiting example, with reference to the attached drawings, wherein:

- Figure 1 shows an osteosynthesis hook plate according to prior art;

- Figure 2 shows an osteosynthesis hook plate according to a first embodiment of the invention, before being assembled;

Figure 3 shows an osteosynthesis hook plate according to a first embodiment of the invention, after having been assembled;

- Figure 4A is a front view of the hook of the plate of Figure 2 - 3; Figure 4B is a rear view of the hook of Figure 4A; - Figures 5 to 9 show subsequent steps of the method of applying the osteosynthesis hook plate of Figures 2 and 3 to a femur;

- Figure 10 shows an osteosynthesis hook plate according to a second embodiment of the invention, after having been assembled;

- Figure 1 I A is a perspective view of the flat body of the osteosynthesis hook plate of Figure 10;

- Figure 1 1 B is a side view of the flat body of the osteosynthesis hook plate of Figure 10;

- Figure 12A is a perspective view of a transversal support of the osteosynthesis hook plate of Figure 10; - Figure 12B is a side view of a support for cortical screws of the osteosynthesis hook plate of Figure 10.

According to Figures 2 and 3, according to the invention the osteosynthesis hook plate 1 according to the invention includes a Hat body 3 having an elongated shape and provided with first through-holes 5 for fastening screws 7 for fastening the plate 1 to a bone and second through-holes 9 for compression screws 1 1 for applying a compression force on the fractured fragments of said bone; the plate 1 further includes a hook 13 provided with hooking elements 15, suitable for engaging and gripping the bone itself. In general, said flat body 3 and said hook 13 are made of metal, preferably titanium. According to the invention, said flat body 3 and said hook 13 are separate pieces that can assume different relative positions with respect to each other and be rigidly fastened through suitable connecting means.

More particularly, according to the first preferred embodiment of the invention that is shown in Figures 2 and 3, said connecting means include a connecting screw 17 which passes through a slot 19 provided in the hook 13 and is screwed inside a hole 21 provided in the flat body 3, thus fastening said hook 13 against said flat body 3. Preferably, as illustrated, the slot 19 is open at its back.

Moreover, the end of the flat body 3 closer to said second through-holes 9 has a tapered portion 23 for guiding the hook 13, the hole 21 receiving the connecting screw 17 being provided in this tapered portion. By the way, it is to be noted that other suitable connecting means can also be employed, provided that they allow the flat body 3 and the hook 13 to assume different relative positions with respect to each other. Among other things, it is also possible to provide the slot in the plate body and the threaded hole for the connecting screw in the hook. As anticipated above, the plate according to the invention is suitable for treating femur fractures, namely fractures of the femur proximal epiphysis (or head). Thus, the flat body 3 of the plate 1 will be sized so that it can be applied to a femur, the first through-holes 5 for the fastening screws 7 being positioned at the femur diaphysis (or body) and the second through-holes 9 for the compression screws 1 1 being positioned at the femur proximal epiphysis. The hook 13, in turn, will be sized so that its hooking elements 15 clasp and grip the femur trocanther so as to facilitate the correct positioning of plate 1.

Said hook 13 is shown in greater detail in Figures 4A and 4B, wherein the hooking elements 15 provided at one end of said hook and shaped so as to grip the trocanther can be clearly seen. At the other end of the hook 13 the slot 19 is provided, which is open at its back for connection to the flat body 3 of the plate 1 : it is evident that, thanks to the length of the slot 19, the hook 13 can assume different positions with respect to said flat body before being rigidly fastened thereto by means of the connecting screw 17, so that the plate 1 can fit the anatomical contour of femurs with different shapes and sizes. Advantageously, according to the first embodiment of the invention shown in Figures 2 and 3, the hook 13 is provided at the slot 19 with a pair of side rails 25 that can slide along the side walls of the guiding portion 23 of the flat body 3, so as to facilitate the alignment of the hook 13 with said flat body and avoid the relative rotation thereof. In Figures 4A and 4B the through-hole 27 provided for an optional cortical screw can also be clearly seen.

With reference now to Figures 5 to 9, the method for applying a plate 1 according to the invention to a bone, namely to a femur 10, is shown.

At first, the body 3 of the plate 1 is applied to the diaphysis of the femur 10 (Figure 5). Then, in a known way, the compression screws 1 1 are inserted with the aid of suitable guide-wires through the through-holes 9 of the fiat body 3 into cavities previously obtained in the femur 10 (Figure 6).

The connecting screw 17 is inserted in the hole 21 provided in the guiding portion 23 of the flat body 3, without being tightened (Figure 7).

By means of pliers 20 or similar tools, the hook 13 is brought close to the Hat body 3, it is aligned thereto by means of side rails 25 and it is made to slide thereon until it reaches the position wherein it correctly clasps and grips the trocanther of femur 10; at this stage, since the connecting screw 17 is still loose, the slot 19 of the hook 13 can freely translate with respect to the connecting screw stem without any impediment (Figure 8). Once the hook 13 has been placed in the most appropriate position, the connecting screw 17 is tightened, so as to fasten the hook 13 against the Hat body 3 and therefore rigidly couple together said hook and body. Finally, the fastening screws 7 are inserted through the through-holes 5 of the body 3 into cavities obtained in the diaphysis of the femur 10 (Figure 9). With reference now to Figure 10, a second preferred embodiment of the osteosynthesis plate according to the invention is shown.

As disclosed above in connection with the first embodiment of the invention, the osteosynthesis hook plate T includes a fiat body 3' having an elongated shape and provided with first through-holes 5' for fastening screws 7 ^" and second through-holes 9' for compression screws 1 1 '; the plate 1 ^' further includes a hook 13' provided with hooking elements 15", said flat body 3' and said hook 13 ^" being separate elements that can assume different relative positions with respect to each other and be rigidly coupled through suitable fastening means.

With reference also to Figure 1 1 A and 1 1 B, according to this second preferred embodiment of the invention, the fiat body 3' further includes a plurality of depressed and flattened transversal portions 29 ^" , provided with a threaded hole 31 ', intended to receive corresponding transversal screw-carrying supports 33 ^" . Also said screw-carrying supports 33 ^" will be preferably made of titanium. The screw-carrying supports 33 ^" - also shown in greater detail in Figures 12A and 12B - include a central portion 33a ^" . that is intended for being received in a depressed and flattened transversal portions 29 ^* of the flat body 3 ^" and to this aim has an outline and sizes which are complementary to the one of said transversal portions 29 ^* . Connecting means are provided for rigidly fastening the central portion 33a' of a screw- carrying support 33 ^" against a corresponding depressed transversal portion 29 ^* of the flat body 3". In the illustrated example, said connecting means comprise a connecting screw 41 ' passing through a through-hole 39 ^* provided in the central portion 33a' of the screw- carrying support 33 ^' and suitable for being screwed in the underlying threaded hole 31 ' of the transversal portion 29 ^" of the flat body 3'. Obviously, any other suitable connecting means for fastening the screw-carrying support 33' against a corresponding transversal portion 29 ^" can also be used.

The screw-carrying supports 33 ^" further comprise two side portions 33b ^" . inclined with respect to said central portion 33a ^" and each provided with a corresponding through-hole 35 ^" for a cortical screw 37 ^* . As clearly visible in Figure 10, once the screw-carrying support 33" has been fastened to the flat body 3', two cortical screws 37 ^" , one at each side of the flat body 3', can be inserted in the through-holes 35 ^' of the support 33 ^" and screwed in the fractured bone. Thanks to the inclination of the side portions 33b ^" of the support 33 ^* , the screws 37 ^* will easily penetrate into the fractured bone, thus contributing to steadily maintain the osteosynthesis plate 1 ^' in the correct position, as well as to apply a compression force onto the separated parts of the fractured bone. Thanks to the modular structure of the plate 1 ^" , comprising on one hand a flat body provided with a plurality of depressed and flattened transversal portions 29 ^" and on the other hand separate screw-carrying supports 33 ^" , it will be possible, case by case, to associate to the flat body 3' the desired number of screw-carrying supports 33', which can be placed in the optimal position with respect to the flat body 3' for the specific needs of each single case.

Thus, the flat body 3' of the plate 1 ^" will be sized so that it can be applied to a femur; the hook 13', in turn, will be sized so that its hooking elements 15' clasp and grip the femur trocanther; finally, a suitable number of screw-carrying supports 33' will be rigidly associated to the flat body 3', in number and positions depending on the specific surgery intervention.

It is evident from the above disclosure that the modular structure of the osteosynthesis hook plate according to the invention provides for increased versatility and capability of fitting femurs having different shapes and sizes. As a consequence, using the hook plate according to the invention assures on one hand a greater adhesion of the plate to the anatomical contour of the fractured bone and on the other hand the opportunity of obtaining, by using a limited number of parts, osteosynthesis hook plates fitting a large number of femurs having different shapes and sizes.

Moreover, it is evident that the above disclosure is given merely as a non-limiting example and that several modifications and variants can be carried out without departing from the scope of protection as defined by the appended claims.