Impact plate for osteotomized bone parts in animals

Abstract

Impact plate (10) for fixing a chipped or osteotomized bone fragment, which is designed in an insertion direction with a longer, first side (12) and a shorter, second side (14), which is tapered at the impact edge (16) and which has at least two spaced-apart drill holes (19), one of which is formed in the area of ​​the first side (12) and one in the area of ​​the second side (14), wherein the edges lateral to the insertion direction have at least partially serrations (22), wherein a guide pin (24) is provided at the proximal end of the impact plate, which is designed for positioning in an impact aid (30).

Description

Field of the invention

[0001] The invention relates to an impact plate for osteotomized bone parts in animals, in particular in dogs and cats, and an impact tool for impacting such an impact plate. State of the art

[0002] Patellar luxation is a common skeletal disorder in dogs and cats. It occurs predominantly in predisposed breeds, including Chihuahuas, Pugs, French Bulldogs, Miniature Pinschers, Prague Ratters, Poodles, Shih Tzus, Pekingese, Yorkshire Terriers, Bolonka Zwetnas, and Maltese. Among large breeds, Appenzeller Mountain Dogs, Flat-Coated Retrievers, and Newfoundlands are more frequently affected. The patella usually luxates medially; lateral patellar luxation is found only in very few dogs (Vidoni et al., 2005).

[0003] Dogs with patellar luxation are usually young. Symptoms of patellar luxation often include a hopping gait or intermittent lameness in one or both hind limbs. Patellar luxation is diagnosed by palpation. A classification into four grades has become established. However, this grading does not necessarily correlate with the clinical presentation.

[0004] The pathogenesis of patellar luxation remains unclear. A study of patellar luxation in Papillons yielded no conclusions regarding skeletal conformation. The only correlation was found in relation to the miniaturization of dogs. Knee angulation and femoral shape also failed to correlate with the occurrence of patellar luxation. Only the three-dimensional processing of images using high-frequency radiography allowed a research group from Jena (Lehmann et al., 2020) to identify the rotation of the femur during the stance phase, with the foot and tibia fixed, as the cause of the patella being pulled out of the femoral groove by the medial pull of the quadriceps muscle. This rotation is particularly noticeable in dogs with a wide gait, which are found in many of the breeds listed above.The extent to which the phylogenetically defined role of the patella as the original apophysis of the femur, and in most animals now acting as a repurposed free bone piece in the quadriceps muscle complex, plays a role must remain unexplained for the time being.

[0005] Regarding treatment, only medial patellar dislocation will be discussed below. Various approaches exist, depending on the degree of dislocation and the severity of symptoms. The simplest treatment consists of lateral capsular plication using slowly absorbable or non-absorbable sutures. In many cases, this is not long-lasting. The classic treatment involves deepening the femoral sulcus using a wedge or block resection technique, laterally shifting the tibial tuberosity, and fixing it with a tension band. Alternative fixation methods include placing a single screw or a Kirschner wire, provided the tibial crest has not been completely osteotomized. High-grade patellar dislocations can be further fixed with rotational osteotomies of the femur and tibia.Finally, there is an alternative approach in which, instead of repositioning the extensor tendon apparatus with the patella, the femoral groove is moved under the patella. The "Patella Groove" semi-prosthesis is suitable for this purpose.

[0006] The most frequently observed complication is migration of the implants used to fix the osteotomized and laterally displaced tibial tuberosity. Additionally, the sharp Kirschner wire ends can rub under the nearby skin and cause lameness again.

[0007] US Patent 2011 / 118842 A1 discloses a vertebral osteosynthesis material comprising an implant in the form of a clamp with two lateral arms for insertion into the plates of the respective vertebrae to be immobilized and a central arm connecting these two lateral arms. At least one lateral arm has at least one movable section that is movable between an insertion position and an anchoring position, wherein, in the anchoring position, the lateral arm has a cross-section at the movable section that is larger than that of the hole that receives the lateral arm. The lateral arms further have serrations.

[0008] US Patent 4,848,328 A discloses an essentially U-shaped clamp for osteosynthesis, designed to fix the focal point of an osteotomy. The clamp comprises a central bar from which two lateral arms with pointed ends extend, suitable for penetrating the bone. The central bar consists of only two mutually inclined portions, forming an outwardly open obtuse angle without any step. Each of the lateral arms has outwardly projecting ribs.

[0009] German patent DE 299 04 271 U1 discloses an implant for fixing the facet joint between two adjacent vertebral bodies, designed as a U-shaped clamp. The implant has a bridge with laterally projecting arms of different lengths at its ends. The clamp is made of a shape-memory metal that, upon temperature increase, changes shape from a martensitic low-temperature state to an austenitic high-temperature state, with the arms being further apart in the low-temperature state, which is below body temperature, than in the high-temperature state, which is reached when the clamp is heated to body temperature.

[0010] US Patent 2017 / 0196604 A1 discloses an assembly for inserting an implant comprising an implant with a first configuration when it is detachably attached to an insertion instrument, and a second configuration when it is not attached to the insertion instrument, wherein the implant is made of a material that allows the implant to have multiple configurations, wherein the implant has two or more means for fixing it to a bone and means for engaging the insertion instrument, or the insertion instrument has means for engaging the implant, wherein the engagement means do not impede the placement of the implant on the bone.

[0011] DE 10 2013 110 759 A1 discloses a clamp implant for influencing or directing growth in bone areas adjacent to the growth plate, comprising a transverse bar and anchoring arms arranged at the ends of the transverse bar, tapering to points and aligned parallel to each other. After insertion into the bone, the anchoring arms form unilateral fixation points on both sides of the growth plate. The transverse bar has at least one tapered zone that is plastically deformable under bending stress and is formed in any desired position and shape without abrupt transitions between the fixation points.

[0012] DE 10 2009 003 177 A1 discloses an implant for fixing adjacent bone plates, comprising two clamping plates arranged on a guide rod, wherein the first clamping plate is positioned between an end stop of the guide rod and the second clamping plate, and the second clamping plate is slidably guided on the guide rod and lockable relative to the first clamping plate. The second clamping plate can be slid onto a locking or threaded section of the guide rod, and the guide rod has a predetermined breaking point that, when the second clamping plate is locked in place, is located between the two clamping plates. Description of the invention

[0013] The object of the invention is to provide a way to treat patellar dislocation that should prevent the need for subsequent surgery.

[0014] This problem is solved by an impact plate according to claim 1. Further features that elaborate the invention are contained in the dependent claims.

[0015] An impact plate according to the invention for fixing an osteotomized (deliberately severed) or chipped bone part, in particular a hind leg of a dog, which is designed in an insertion direction with a longer, first side and a shorter, second side, which is tapered to a point at the insertion edge, in particular such that a cutting edge is provided, and which has at least two spaced-apart drill holes, one of which is formed in the area of ​​the first side and one in the area of ​​the second side, wherein the edges of the narrow sides lateral to the insertion direction have at least partially serrations.

[0016] Preferably, the first and second sides of the impact plate are designed as ridges. These ridges ensure that the narrow side is in contact with the bone over a longer circumferential area, thereby increasing the adhesion of the impact plate to the bone.

[0017] The impact edge(s) of the bridge or bridges are preferably at least partially straight, perpendicular to the insertion direction (i.e., perpendicular to the insertion direction). Fig. 1a from top to bottom). They can also be partially inclined, but preferably the impact edges are completely straight.

[0018] The prongs can be designed as simple triangles with the same inclination at the front (distal) and back (proximal). However, the front and back sides can also be inclined differently, for example, straight or with an undercut at the back. The sides can also be curved. This better secures the impact plate against falling out. Preferably, the impact plate tapers towards the front in the area of ​​the impact edge with respect to the two large outer sides – the impact edge is therefore chamfered. This facilitates driving the impact plate into place.

[0019] At the end opposite the impact edge, a guide pin is provided, designed for positioning an impact aid. This means that the impact plate can be moved to the intended position and held there using this guide pin. This facilitates both positioning and impact of the impact plate. Preferably, at least one notch is provided at the base of the guide pin. This allows the guide pin to be easily removed after the impact plate has been driven in, preventing it from interfering with the animal's movement.

[0020] Furthermore, the invention can be directed to a kit that, in addition to the impact plate, also includes an impact aid, which can be designed as a cylindrical rod with one flat side and one side with a receptacle for the guide pin. This receptacle is preferably designed such that insertion parallel to the longitudinal axis of the guide pin is possible. The cross-section of the cylindrical rod of the impact aid is not limited to circular cross-sections, but can be designed as desired, for example oval, triangular, any other polygonal shape, or even as an irregularly shaped cross-section. Brief description of the characters Fig. Figure 1a shows an impact plate according to the invention with a guide pin. Fig. 1b shows a side view of the impact plate made of Fig. 1a. Fig. Figure 1c shows a magnification of the serrations on one side of the impact plate. Fig. Figure 2a shows an impact plate according to the invention with a wider guide pin and with curved teeth. Fig. 2b shows a magnification of the teeth on one side of the impact plate. Fig. 2a. Fig. Figure 2c shows an overhang of the teeth towards the proximal area of ​​the impact plate. The Fig. Figures 3a to 3c show an impact aid from a top, side and bottom view. Fig. 4 shows an impact plate made of Fig. 1a, which is inserted into a driving aid. The Fig. Figures 5a to 5f schematically show different designs of impact plates. Description of the preferred embodiments

[0021] The impact plates 10 are generally made of titanium. Other biocompatible materials suitable for implants, particularly metals but also ceramics, can be used. The impact plates 10 come in various lengths and widths, which are tailored to the specific animal being operated on. Generally, the lengths and widths range from 10 to 50 mm. The thickness of the impact plates 10 is approximately 0.5 to 2.0 mm, also depending on the animal being operated on.

[0022] A first side 12 of the impact plate 10 projects further forward (i.e., is longer) than a second (i.e., shorter) side 14. This allows the impact plate 10 to be better adapted to the insertion position, since the upper end of the femur is somewhat more robust than the portion below it. Preferably, both sides of the impact plate 10 are designed as projections or ridges with a recess or gap between them. The front side of the impact plate 10, which faces the bone during insertion, is referred to below as the distal end 18, while the side on which the impact impulse is applied and which faces the user is called the proximal end 20.

[0023] Fig. Figure 1 shows an impact plate 10 according to a preferred embodiment of the invention. The first and second sides 12, 14 are each designed as a rib, between which there is a gap, so that an asymmetrical “U” is formed, in which the first side 12 is longer than the second side 14.

[0024] The distal end 18 of the parts that are driven into the bone is preferably tapered, so that a cutting edge 16 is formed at the distal edge. The cutting edge 16 is preferably a maximum of 0.4 mm thick at the end, and more preferably a maximum of 0.2 mm thick. The inclination can be provided on both sides (in Fig. 1b above and below) or, as it actually is in Fig. 1b is shown only on one side (in Fig. 1b only the upper side is sloped). The inclination of the impact edge 16 is preferably a maximum of 45°, more preferably a maximum of 35° or 25°. The distal end of the connecting piece 15, which connects the two webs of the first and second sides 12, 14, can also be tapered.

[0025] The bridges can be designed in almost any way imaginable. For example, viewed from above, the bridges can taper towards the distal end 18 and can have rounded or beveled corners and edges. Various designs are shown as examples in the Fig. Figures 5a to 5f are shown. In the preferred version, however, the webs are rectangular in a top view.

[0026] On the outer surfaces 12a, 14a and / or, if applicable, on the inner surfaces 12b, 14b, teeth 22 may be provided to increase the retention of the impact plate 10 in the bone. As in Fig. As shown in Figure 1c (enlarged), the prongs 22 are preferably formed as symmetrical triangles, such that the distal and proximal sides of each prong 22 have the same inclination. A tapered inclination on the distal side of the prong 22 is advantageous to avoid creating significant resistance when the impact plate 10 is driven in. The same applies to the proximal side if the impact plate 10 is to be removed later. However, the front and rear sides can also be inclined differently. For example, the proximal side can have a smaller or no inclination (i.e., perpendicular to the outer surface 12a, 14a) or even an undercut similar to a barb, which makes it more difficult to pull out the impact plate 10 and thus ensures that the impact plate 10 is particularly firmly in place after insertion. The prongs 22 can also be curved. This provides better protection against the impact plate 10 falling out.Curved teeth 22 are in the in . Fig. The embodiment shown in Figure 2a is illustrated. The curved prongs 22 can also be symmetrical or at least have straight sides before being driven in. Only during driving in do the prong tips bend and the prong sides curve towards the proximal end 20 as they penetrate the bone. The prongs 22 are preferably present over the entire length of the first and second sides 12, 14 that are to be driven into the bone. The contour of the prongs 22 can also be arcuate. Regardless of the specific design, the prongs 22 preferably project beyond the outer edge of the proximal region of the driving plate 10 by a distance a. That is, the prongs 22 are somewhat wider than the unprongled edge, as shown in Figure 2a. Fig. 2c is shown as an example.

[0027] At the proximal end 20, one or more drill holes 19 are provided (two drill holes 19 are shown) through which the impact plate 10 is attached to the chipped bone fragment by means of fastening pins, thus holding it in place on the leg bone. The corners at the proximal end are preferably rounded to prevent possible postoperative injuries caused by the movements of the operated animal.

[0028] A guide pin 24 can be formed at the proximal end 20, which can be used to hold the impact plate 10 during insertion. This guide pin 24 serves in particular to support the impact plate 10 in an impact aid 30. Preferably, the guide pin 24 therefore has a notch 23 directly at the proximal end 20 of the impact plate 10, which serves as a predetermined breaking point when the impact plate 10 is inserted. The notch 23 can be formed on one side only, but can also be provided symmetrically on both sides of the guide pin 24, as shown in Fig. 1a is shown.

[0029] In the Fig. Figures 3a to 3c show an impact aid 30 that assists in driving in the impact plate 10. The impact aid 30 is preferably made in one piece and, in particular, of metal. This ensures ideal transmission of the impulse. At the distal end 32, a receptacle 36 for the guide pin 24 is formed, which essentially comprises a recess with a ridge 37 at the distal end 32 to prevent the guide pin 24 from falling out. Furthermore, the impact aid 30 has a grip area 38 by which it is held during use. The proximal end 34 is flat, allowing an impulse to be applied to the impact aid 30 with a striking instrument, such as a hammer, and transmitted to the impact plate 10. The distal end 32 of the impact aid 30 therefore rests directly against the proximal end 20 of the impact plate 10 to improve impulse transmission. The cross-section of the impact aid 30 is not specified.However, the round or polygonal cross-section shown, i.e. a cylindrical design, is preferred.

[0030] In the Fig. Figures 5a to 5f schematically illustrate different embodiments of the impact plate 10 according to the invention. In all these embodiments, the previously mentioned configurations can be applied; for example, the distal end 18 can have a cutting edge as described above, or lateral serrations 22. Fig. 5a has two rectangular bridges with slightly rounded corners and essentially corresponds to the one in the Fig. 1a and Fig. The embodiment shown in 1b. Fig. 5b has converging ribs where the outer sides are curved or swung inwards and become thinner towards the distal end 18. Fig. 5c is generally the same design as Fig. 5a, with the difference that the distal ends of the ribs are chamfered on the outer sides. This improves the setting properties of the impact plate 10. Furthermore, in this embodiment, a recess or notch 39 is formed, which serves as a predetermined breaking point and makes it possible to break off the corresponding rib if the impact plate 10 should be too wide (e.g., for small animals). One or more such recesses can, in principle, be provided on each of the impact plates 10 shown in this application. Fig. 5d is generally the same design as in Fig. 5a shown, with the distal ends of the webs ending in a semicircle. Fig. 5e shows an embodiment with converging webs, which corresponds to the one in Fig. 5b is similar, with the distal ends of the ribs ending straight. At the proximal end 20 there are two notches 39. Finally, in Fig.Figure 5f shows an embodiment in which no webs are provided, but the first side 12 slopes down towards the second side 14. Reference symbol list 10 Impact plate 12 first page 12a Outside 12b Inside 14 second page 14a Outside 14b Inside 15 distal end of the connector 16 Impact edge 18 distal end 19 borehole 20 proximal end 22 points 23rd notch 24 guide pins 30 impact aid 32 distal end 34 proximal end 36 recording 37 Bridge 38 Grip area 39 notch a distance

Claims

[1] Impact plate (10) for securing a chipped or osteotomized bone part, which is designed in an insertion direction with a longer, first side (12) and a shorter, second side (14), which is tapered at the impact edge (16) and which has at least two spaced-apart drill holes (19), one of which is formed in the region of the first side (12) and one in the region of the second side (14), wherein the lateral edges to the insertion direction have prongs (22) at least in sections, wherein a guide pin (24) is provided at the proximal end of the impact plate, which guide pin is designed for positioning in an impact aid (30). [2] Impact plate (10) according to claim 1, wherein the first and second sides (12, 14) are formed as webs. [3] Impact plate (10) according to claim 2, wherein the impact edges of the webs are at least partially straight or rounded transversely to the insertion direction. [4] Impact plate (10) according to one of the preceding claims, in which the prongs (22) are straight on their proximal side or are provided with an undercut. [5] Impact plate (10) according to one of the preceding claims, in which the outer sides (12a, 14a) are designed to converge towards one another at the impact edge. [6] Impact plate (10) according to one of the preceding claims, wherein at least one notch (23) is provided at the base of the guide pin (24). [7] Impact plate (10) according to one of the preceding claims, further comprising an impact aid (30) which is designed as a cylindrical rod with a flattened side (34) and a side with a receptacle (36) for the guide pin (24).

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