MXPA00004619A - Implant for stabilizing a fracture and screw for use in surgery - Google Patents

Abstract

According to the invention, a plate, especially for the upper arm, has guides for preferably two screws which steadily holds the screws such that they are at an angle relative to said plate. In addition, the screws are preferably fixed toa fixing device such that they can be detached and are prevented from turning in the screw shaft and displacing in a direction of the screw shaft. To this end, a special screw is provided which has an outer thread diameter that is larger than the adjacent shaft diameter. The shaft diameter increases in the area of the screw head in order to guarantee a sure guiding.

Description

IMPLANT TO STABILIZE A FRACTURE DESCRIPTION OF INVENTION invention relates to an implant for stabilizing a fracture of arm in area of head of humerus, with or without participation of tubers, with a plate in which holes for screws are provided, plate being it has a guide for humeral head screw that holds screw of humerus head at an angle to plate. As an implant of type under consideration, it is known from US Pat. No. 5,693,055 to provide a supplement and conduction plate, which absorbs forces at head of screw and by means of a wider seating surface on diaphyseal bone of arm. get (that e is) less tension in diaphysis. guide plate rests on diaphyseal bone in direction of a supplementary plate, and is only fixed against diaphyseal bone by screw that is inserted in head of humerus. Accordingly, this function of implant described in US Pat. No. 5,693,055 depends on screwing force on head of humerus, and on interfragmentary compression that occurs with it, which, according to experience, however decreases in course of hours to days due to a bone sintering (solidification) that goes into effect regularly. Ano implant is known from US 4,657,001. However, this implant is only suitable for thigh area and also leads to an interfragmentary compression. Accordingly, object of invention is to improve an implant of type under consideration with which a simple and safe stabilization of fracture can be achieved. This object is achieved by providing on plate a trapping device that stably fixes screws of head of humerus against a displacement in direction of diaphysis, preferably so that can be removed. Such a clamping device blocks movements of screws with respect to plate and thus ensures a rigid holding implant which can not be loosened even in case of sudden movements of arm. By using two screws on head of humerus not only ensures an angularly stable fixation of one with respect to o of fragments of head and bone diaphysis, but also achieves a stability of rotation that prevents screws of head of humerus loosen, for example in case of pendulum exercises. An exemplary embodiment provides that guides are drilled parts whose circular sections correspond to a diameter of rod of screws of head of humerus. e guides take advantage of thickness of plate to retain screws at an angle. For this purpose internal diameter of drill is adapted to at least one section of bore precisely to external diameter of a section of screw shank, so that although it is possible to insert screw in bore, screw can only be move in direction of axis of screw shank. It is true that this configuration requires a certain thickness of plate, but neveress it is preferable to guides that protrude above surface of plate or, on contrary, penetrate bone. angle predefined by guides should correspond approximately to physiological angle of head of humerus. efore, an angle between 35 ° and 40 ° is proposed, possibly of 37.5 ° measured with respect to longitudinal axis of shaft of arm. A preferred configuration of a clamping device provides that between holes of screws of head of humerus a slot with a transverse perforation is provided. In this transverse perforation, a screw can be inserted so that when screw is screwed, slit narrows. This leads to diameter of holes being slightly deformed, fixing the screws of the head of the humerus so that they retain their angular position. Preferably the holes of the screws of the head of the humerus are arranged parallel to each other, so that their axes are in a plane with the longitudinal axis of the shaft of the arm. By this the axes of the screws of the head of the humerus cross the longitudinal axis of the shaft of the arm under the predefined angle which is preferably 35 ° -40 °. This arrangement of the screws in a line means that in only one operation it is necessary to discover very little bone in the region of the fracture. This leads to a faster bone recovery by virtue of avoiding hyperemia disorders. In order to be able to accommodate wire or PDS maneuvers for refractoring torn tubers, it is proposed to provide perforations in the plate that extend parallel to their upper and lower sides. These perforations are preferably provided in the area of the tip of the plate and in the area of the pinching device.

One embodiment of the plate has a very compact design. This plate has a maximum length of 100 mm, a maximum width - of 12 mm, and its thickness is approximately between 4 mm and 9.5 mm. A particular configuration of the guide of the screws allows a maximum thickness of the plate of approximately 7 mm. In its outline the plate adapts to the anatomical conditions in the region of the proximal humerus. In the lower section the plate is screwed to the proximal part of the shaft of the arm with cortical screws customary in the trade. Since no large bending moments occur in this region near the joint, a fixation with three screws is sufficient. To treat fractures radiating to the arm shaft region, it is also possible to make the longer plate with a correspondingly greater number of screw holes in the region of the arm shaft. Various embodiments of the invention are shown in the drawing and are described in more detail below. They show: Figure 1 a longitudinal section through the plate fixed to the bone of the arm with screws, Figure 2 Several views of the plate highlighted in drawings with a gag screw, Figure 3 as a singularity the placement of the gag screw, 4 shows an alternative possibility for clamping the screw of the head of the humerus in the area of the seat of the plate, figure 5 another alternative for the clamping by means of a threaded screw head, figure 6 a humerus head screw, 7 shows a section of the thread of the humerus head screw according to FIG. 6, FIG. 8 a longitudinal section through an alternative embodiment of a plate fixed with screws to the arm bone, and FIG. 9 a detail. amplified from figure 8. Figure 1 shows an arm bone with proximal humerus fracture, type III according to Neer. The reproduced part of the broken arm consists of the head 2 of the humerus and the proximal portion of the shaft 3 of the arm. Plate 4 rests against the proximal humerus and in its contour it adapts to the anatomical conditions of the proximal humerus area. The total length of the plate is 95 mm, its thickness in the region of the proximal portion of the shaft of the arm is around 4 mm, and in the region of the head of the humerus it is widened to 9.5 mm. The width of the plate is 12 mm maximum.

In the lower section this plate is screwed with commercially available cortical screws 5, 6, 7 to the proximal portion 3 of the arm shaft.

(• The housings for the special screws 8 and 9 of the humerus head 5 are executed in the upper section of the plate 4 as jaws 10 which allow firm clamping of the screws 8, 9 of the head of the humerus with the plate 4 Figure 2 shows plate 4 highlighted in representation on a natural scale. In the lower section 11 of the plate 4, three perforations 12, 13, 14 are manufactured in one line, of which the central perforation 13 is made as an oblong hole. These perforations are configured to house the screws 5, 6, 7 cortical usual in commerce. Between these perforations the plate presents notches 15 and 16, by means of which a more uniform distribution of the stresses in the plate is achieved. The seat surface 17 is not made flat but concave, whereby the plate feels better against the surface of the arm bone. The lines 18 and 19 constitute the visible edges of the notches 15 and 16, which are represented by virtue of the concave conformation of the plate. So in this does not deal with recesses, the plate settles two-dimensionally.

The upper part 20 of the plate 4 has guides 21, 22 as housings for the screws 8 and 9 of the head of the humerus. These guides are manufactured with an angle 23 ("37.5 ° with respect to the longitudinal axis of the arm.) This corresponds approximately to the physiological angle of the head of the humerus.These guides are configured as bores having a larger diameter to accommodate a screw head 24 and a somewhat smaller diameter. to accommodate a thickened screw rod 25. The depth of the guides 21, 22, and thereby the thickness of the plate in this region is selected such that the length of the guide reaches just to provide the screw 8 and 9 a secure fixation in a predefined angular position. The plan view illustrated in figure 2 on the upper part 20 of the plate 4, shows that a slit is provided in the plate between the holes 21, 22 which serve as guides. Transversally to this slit a perforation is provided in which a clamping screw 27 can be screwed. Figure 3 shows the clamping of the screws 8 and 9, and in particular of their enlarged parts, by means of the gagging device 28. By screwing the clamping screw 27 into the thread of the bore 26 they move one towards the other. the other the parts of the plate 4 which are on both sides of the slit 29, so that the slit 29 narrows. By this the circular sections of the guides 21, 22 are also slightly deformed, so that the walls of the guides are pressed against the enlarged part 25 of the shank of the screws 8 and 9. By this, in addition to the fixed angular position , the screws 8 and 9 (also) are fixed against a rotation about the axis 30 of the screw and against the displacement in the direction of the displacement axis 30. Figure 4 shows an alternative clamping device 31. In this form of imprisonment in the plate 4 of the screws 8 and 9 of the head of the humerus, the head 32 of the screw is split and in its interior a conical bore 33 and a thread 34 are provided. Immediate to the inner end of the screw. the thread 34 is in the screw a hexagon 35 inside, with which the screw 8 can be screwed to the head of the humerus. After the screw 8 is screwed, the conical screw 36 is screwed, also with an internal hexagon 37 on the thread 33 of the screw 8. By this, the split head 32 of the screw 8 of the head of the humerus is separated by pressure, with what remains firmly imprisoned in the plate 4. In figure 5 another alternative of a trapping device 38 is shown. In this manner of clamping the screw 8 of the head of the humerus, the rod adjacent to the head 39 of the screw is made as an external thread 40, and the housing 41 of the plate serving as a guide for the screw, as a corresponding internal thread. The internal diameter of the thread of the plate 4 is at least as large as the diameter of the thread of the sponge of the screw 8 at the end of the screw. The passages of the thread 40 of the head of the screw and of the thread of the spongiosa on the end of the screw must be approximately equal so that the screw 8 of the head of the humerus can be introduced. In addition, the thread pitch 40 has to be designed in such a way as to guarantee self-retention. When the screw 8 of the head of the humerus is screwed in, it is finally screwed firmly, with which a secure grip of the screw 8 of the head of the humerus is achieved in the plate 4. In comparison with both variants described above, this variant does not allow well only a minimum interfragmentary compression. Because of this, it acts functionally as an internal fixator of the head of the humerus. Transversally to the path of the humerus head screw guides described there are provided perforations 42, 43 in the plate which serve to accommodate wire or PDS maneuvers for refining torn tubers. In figure 6 a screw 8 is shown, which in its structure is analogous to screw 9 except for the length. This screw consists of the head 44 of the screw, the rod 45 of the screw and the thread 52. The rod 45 of the screw first has a conical configuration towards the head 44, so that it widens in the area of the head 44. This part 46 enlarged of the rod configured along a section of the rod has a diameter 47 of the enlarged rod with respect to the remaining diameter 48 of the rod. The external diameter 49 of the thread 52 is larger than the diameter 48 of the part 45 of the rod. However, it is the same size or smaller than the diameter 47 of the enlarged part 46 of the rod. The screw 8 has a central hole 50 that allows it to be placed through a special guide wire system, and on the head 44 of the screw an internal hexagon 51 is provided to screw the screw 8. In order to guarantee an adaptation of The length of screw required, the lengths of these screws are provided in 5 mm intervals between 40 mm and 80 mm. This allows to select the correct screw length in each case for different fractures and different bones. A thread is provided on the screws for the spongiosa. In figure 7 a thread of this kind is represented. For the field of application according to the invention, the screw of 6.5 mm thread for spongiosa of the usual trade is not provided, but a screw with 8.5 mm of thread for spongiosa. This screw produces significantly higher clamping forces in the bone and therefore is also suitable for use in the case of bones with strong osteoporotic alteration. The construction of the plate shown in FIG. 8 is substantially analogous to the construction of the plate according to FIG. 1. However, the plate is made substantially narrower in the region of the screw housing of the head of the humerus. The screws 53 and 54 of the head of the humerus no longer have a lentil head as shown in figure 1, but end with the rod 55 or guide 56. In order to provide the screw 53 or 54 of the head of the humerus with a support on the plate 57, the bore 58 of the plate 57 is not through but is directly reduced where it sits against the bone 59 forming an angle 60 of approximately fifteen. Due to the oblique position of the bore 58 in the plate 57 a "bead" is thus produced which acts as a support for the screw 54 or else the screw 53. To the thread 61 of the spongiosa of the screws 53 and 54 of the The head of the humerus can also be provided with an external diameter which is so small that it can be inserted without any problems through the narrowed bore 58, or else the "heel" and the thread of the spongiosa are adapted to each other in such a way that the the head of the humerus can be screwed into the narrow area of the bore 58 without any problem. By this preferred embodiment, the plate 57 can be configured around 25% to 30% narrower than the plate 4. Its maximum width is already only of 7 mm. In this case, the cortical screws 62, 63, 64 of the part of the stem of the plate 57 bulge by approximately 6 mm. For construction reasons the thread of the gag screw 65 was reduced from M5 to M4, and the bore 66 for receiving a PDS maneuver or a wire was transferred to the upper end of the plate 57.

Claims (1)

1. CLAIMS Implant to stabilize a fracture of the arm in the area of the head of the humerus, with or without involvement of the tubers, with a plate in which holes for screws are arranged, the plate having a guide for a screw of the head of the humerus that maintains the screw of the head of the humerus stable forming an angle with respect to the plate, characterized in that the plate comprises a clamping device that stably fixes the screws of the head of the humerus, preferably in removable form, against a displacement in the direction of the rod. Implant according to claim 1, characterized in that the plate preferably comprises guides for two screws of the head of the humerus. An implant according to claim 1 or 2, characterized in that the guides are parts of bores whose circular sections correspond to a diameter of the rod of the screws of the head of the humerus. Implant according to one of the preceding claims, characterized in that the angle is between 35 ° and 40 °, and preferably is 37.5 °. Implant according to one of the preceding claims, characterized in that a slit with a transverse perforation between the holes of the screws of the head of the humerus is provided on the plate as a clamping device. Implant according to one of the preceding claims, characterized in that the axes of the holes of the screws of the head of the humerus lie in a plane with the longitudinal axis of the shaft of the humerus. Implant according to one of the preceding claims, characterized in that the plate comprises perforations extending parallel to its upper and lower sides. Implant according to one of the preceding claims, characterized in that the plate has a maximum thickness of approximately 6 to 8 mm. Implant according to one of the preceding claims, characterized in that the plate has a maximum width of 12 mm. Surgical application screw having a screw head and an outer diameter of the thread that is greater than the diameter of the abutting rod, characterized in that the diameter of the rod in the area of the screw head is at least as large as the diameter outside of the thread and less than the diameter of the screw head. Screw according to claim 10, characterized in that the screw has a spongiosa thread. Screw according to claim 10 or 11, characterized in that the screw comprises a longitudinal perforation.