Fracture fixator

Abstract

The invention relates to medical instruments, in particular to a fracture fixator. The fracture fixator comprises a fixing needle and a fixing plate, the fixing needle comprises a needle body with a needle tip at one end, an expansion portion is arranged on the section, close to the needle tip, of the needle body, and an easily-folded portion is arranged on the side, away from the needle tip, of the expansion portion. One end of the fixing plate is provided with a fixing hole, and the other end of the fixing plate is provided with grooves matched with the expansion parts on the fixing needles. The device is suitable for reduction and compression fixation of micro bone block fractures in joints and near joint areas, bone block fragmentation can be effectively prevented, and the fixing effect is good.

Description

Technical Field

[0001] This invention relates to medical devices, specifically to a fracture fixation device. Background Technology

[0002] In orthopedic clinical practice, the fixation and treatment of intra-articular fractures and periarticular small bone fragment fractures (such as the coronoid process of the ulna, the posterior wall of the acetabulum, and the medial and lateral malleoli) still face significant technical bottlenecks. Currently used internal fixation devices have certain deficiencies in both structural design and mechanical properties, making it difficult to simultaneously meet the requirements of minimally invasive operation, morphological adaptation, and biomechanical stability. Specifically:

[0003] 1. Mechanical compatibility defects of traditional hollow screws

[0004] Hollow threaded screws can easily cause iatrogenic bone fractures when fixing bone fragments smaller than 5mm. Their rigid thread structure does not match the elastic modulus of cancellous bone, which can easily create a stress shielding effect around the screw track, accelerate local osteoporosis, and increase the risk of postoperative refracture.

[0005] 2. Insufficient mechanical strength of absorbable materials.

[0006] Polylactic acid absorbable screws have an initial shear strength of only 15%–30% that of metal screws. They also have a low torque tolerance threshold during insertion and a high fracture rate. Postoperative external fixation time needs to be extended, which seriously affects the patient's early functional recovery.

[0007] 3. Risk of mechanical failure of suture fixation

[0008] While high-strength sutures can avoid complications associated with metal implants, their low tensile strength makes them vulnerable to muscle tension and can lead to loss of anatomical height of fracture fragments. In particular, the failure rate of fixation increases significantly when the joint is subjected to rotational force.

[0009] 4. Defects in bone fit of anatomical plates

[0010] Conventional anatomical locking plates have significant limitations when treating avulsion, splitting, or atrial fractures: insufficient distal holding force, fewer screw anchor points, and reduced pull-out strength; the radial stress generated during screw implantation can easily lead to further splitting of the bone fragments; in addition, the fixation failure rate increases significantly when the pre-shaped curvature of the plate does not match the three-dimensional morphology of the bone fragments.

[0011] 5. Stability defects of Kirschner wire fixation

[0012] Simple Kirschner wire fixation lacks a threaded anchoring mechanism, making it prone to displacement postoperatively. Excessive micromovement can significantly increase the risk of delayed fracture healing and cannot meet the early active movement requirements of enhanced rehabilitation surgery.

[0013] Existing technology CN114176746A discloses a fractureable phalanx or phalanx minimally invasive internal fixation pin, including a pin body, a pin hub, and a pin handle. One end of the pin hub has the pin body, and one end of the pin handle has a tapered connecting portion. The pin handle is connected to the other end of the pin hub via the tapered connecting portion, and the pin handle has anti-slip textures. This solution only provides a fractureable fixation pin. After breakage, the fracture surface is a plane. Such a fixation pin only has a certain positioning function for the fracture fragments, but does not provide good fixation.

[0014] Existing technology CN118285892A describes a compressible fixation device for coronoid process fractures of the ulna, comprising a breakable semi-threaded Kirschner wire, divided into a proximal smooth shaft, a breakable articular portion, a ball portion, a distal smooth shaft, a distal threaded portion, and a tip portion; a coronoid process claw, divided into a body and a fixation claw, with a hollow ring at the center of the body, and the fixation claw securely fixing the coronoid process fracture fragment; and a nut, which matches the distal threaded portion of the Kirschner wire and provides compression. This device uses a semi-threaded Kirschner wire, requiring penetration through the fracture site before fixation via the nut. The ball portion of the broken Kirschner wire is also fixed via the hollow ring on the coronoid process claw, providing relatively good fixation of the fracture fragment. However, this device still has significant limitations. Firstly, the use of a threaded Kirschner wire and nut means the Kirschner wire diameter cannot be too small, otherwise the nut fixation will be impossible. Secondly, nut fixation requires the Kirschner wire to penetrate the fracture site, making it unsuitable for intra-articular and near-articular microfractures.

[0015] In summary, existing internal fixation devices struggle to achieve a good balance between the feasibility of minimally invasive procedures for intra-articular and near-articular microfractures, bone fragment morphology adaptation, and biomechanical stability. Therefore, there is an urgent need to develop a novel internal fixation device to address these issues. Summary of the Invention

[0016] The present invention aims to overcome the shortcomings of the prior art and provide a fracture fixator that can be inserted minimally invasively and has multidimensional fit and stability.

[0017] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0018] A fracture fixation device includes fixation pins and a fixation plate.

[0019] The fixing needle includes a needle body with a needle tip at one end. A bulging part is provided on the part of the needle body near the needle tip, and an easy-break part is provided on the side of the needle body away from the needle tip.

[0020] One end of the fixing plate has a fixing hole, and the other end has at least one groove that matches the enlarged part on at least one fixing pin.

[0021] Since these instruments are used in orthopedic surgery, their materials obviously need to meet medical requirements and strength requirements. Fortunately, existing technologies provide various medical materials, such as medical-grade titanium alloys, stainless steel, zinc-magnesium alloys, and absorbable materials. For the fixation pins, sufficient strength is required to allow them to be smoothly inserted into the bone tissue, while the fixation plates need good plasticity to adapt to the bone contour of the fracture site, allowing for a relatively close fit. Alternatively, 3D printing can be used to personalize the fixation plates according to the specific bone contour of the patient's location. In this case, the plasticity of the material used to manufacture the fixation plates does not need to be particularly emphasized.

[0022] When performing fracture fixation surgery using the fracture fixator provided by this invention, a fixation pin can generally be implanted into a small bone block through a minimally invasive incision and connected to fix the fracture site. Because the diameter of the fixation pin can be made relatively small, iatrogenic damage to the bone block (such as splitting) can be minimized, achieving precise reduction and temporary fixation of the fracture. Once the enlarged portion of the fixation pin is in close contact with the cortical surface of the bone block, the fixation pin is broken off along its breakable section and removed, leaving only the enlarged portion embedded in the fixed bone block, minimizing implant residue. Depending on the size and shape of the bone block, at least one fixation pin can be implanted at a selected location.

[0023] During the procedure, the fixation plate is pre-bent in the thickness direction according to the anatomical curvature of the fracture site to ensure maximum conformity to the bone surface. The groove of the fixation plate is then placed over the implanted enlargement. A lag screw is used, for example, to fix the fixation plate to the main bone block through the first fixation hole. As the lag screw is tightened, the fixation plate exerts compressive stress on the enlargement, resulting in stable reduction and fixation of the fracture site.

[0024] Furthermore, the diameter of the needle body is 0.5-1.5 mm. According to one embodiment of this application, the selection of the diameter of the fixing needle is related to the strength of the material. Under the condition of ensuring strength, it is best to choose a smaller diameter.

[0025] Furthermore, the maximum width of the enlarged portion is 2.0-2.5 mm. According to one embodiment of this application, the enlarged portion is not an ideal spherical shape, but can maintain a smooth outer surface, such as an olive shape or an ellipse shape. At the same time, the enlarged portion matches the groove on the fixing plate so that it can be fixed by the fixing plate.

[0026] Another consideration is that the breakable portion should be tightly attached to the surface of the bulge. This breakable portion can be formed by slotting into the needle body, or by designing its diameter to be smaller than other parts of the needle body, while ensuring it does not break when the needle is inserted. The breakable portion can be achieved through physical subtraction and structural design techniques in existing technologies. For example, a ring-shaped "V" or "U" groove can be machined at a predetermined break point on the needle body using turning or grinding processes, significantly reducing the cross-sectional area at that point and making it the weakest point on the entire needle body, thus allowing it to break at that location. Existing technologies also provide other methods to achieve a breakable portion at a specific location on a needle-like object.

[0027] Furthermore, the distance between the enlarged portion and the needle tip is 20-30 mm. According to one embodiment of this application, this length needs to take into account the scenario in which the fixator is applicable, and can be measured and trimmed during the operation. Therefore, the distance between the enlarged portion and the needle tip needs to be determined according to the fracture site.

[0028] Furthermore, the fixation hole includes a first fixation hole and a second fixation hole. The second fixation hole is used to place a temporary fixation pin in the early stage of surgery to position the fixation plate; the first fixation hole is used to connect and fix the fixation plate to the bone tissue by, for example, passing a lag screw through the first fixation hole.

[0029] Furthermore, the first fixing hole is provided with an internal thread.

[0030] Furthermore, the groove is an elongated groove used to accommodate the enlarged portions on multiple fixing pins.

[0031] Furthermore, the grooves are multiple and independently arranged, with each groove matching and pressing the enlarged portion of a fixing needle. The position of each groove can be determined in advance according to the predetermined position of the fixing needle to be inserted after the surgical plan is determined.

[0032] This invention achieves three advantages that are difficult to achieve simultaneously in existing technologies through the combined design of fixing pins and fixing plates:

[0033] 1. Highly adaptable to extremely small bone fragments, effectively avoiding bone fragment fractures caused by hollow screws;

[0034] 2. The press-fit locking between the enlarged part and the groove significantly improves the pull-out resistance and rotation resistance of the fracture fixator. Compared with Kirschner wires, it improves the pull-out resistance. Three-dimensional finite element analysis shows that under physiological load, the micromotion amplitude is far below the threshold of delayed fracture healing.

[0035] 3. The malleable fixation plate and multi-point groove design allow for unified locking of multiple bulges with different spacing and angles within a 360-degree range, greatly improving the fit and pressure fixation effect for complex periarticular fractures such as avulsion and splitting.

[0036] 4. This invention is applicable to the reduction and compression fixation of microfractures in and near the joint, effectively preventing bone fragments from fracturing and providing excellent fixation. It also creates conditions for early rehabilitation exercises for patients while ensuring good reduction and fixation, thereby achieving better treatment results. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a fixing pin structure according to an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of a fixing plate structure according to an embodiment of the present invention;

[0039] Figure 3 This is a structural diagram of the easily foldable portion according to an embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of the structure of the fixing plate according to another embodiment of the present invention;

[0041] Figure 5 This is a schematic diagram illustrating the usage of the present invention. In the diagram:

[0042] 1-Fixing pin, 2-Fixing plate, 3-Pink tip, 4-Pink body, 5-Expansion part, 6-Easily broken part, 7-Fixing hole, 71-First fixing hole, 72-Second fixing hole, 8-Groove. Detailed Implementation

[0043] The present invention will be described in detail below with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other. For ease of description, the words "upper," "lower," "left," and "right" appearing below only indicate that they are consistent with the upper, lower, left, and right directions of the drawings themselves, and do not limit the structure.

[0044] like Figure 1 - Figure 3 As shown, one embodiment of the fracture fixation device of the present invention includes a fixation pin 1 and a fixation plate 2. The fixation pin 1 includes a pin body 4 with a pin tip 3 at one end. A bulge 5 is provided on a section of the pin body 4 near the pin tip 3, and a breakable portion 6 is provided on the side of the pin body 4 away from the pin tip 3. A fixation hole 7 is provided at one end of the fixation plate 2, and grooves 8 that match the bulge 5 on the fixation pin 1 are distributed at the other end.

[0045] Since these instruments are used in orthopedic surgery, their materials obviously need to meet medical requirements and strength requirements. Fortunately, existing technologies provide various medical materials, such as medical titanium alloys, stainless steel, zinc-magnesium alloys, and absorbable materials. For fixation pin 1, sufficient strength is required to allow it to be smoothly inserted into the bone tissue, while fixation plate 2 needs good plasticity to adapt to the bone contour of the fracture site, allowing it to fit relatively closely to the bone. Alternatively, 3D printing can be used to personalize the fixation plate according to the specific bone contour of the patient's location. In this case, the plasticity of the material used to manufacture fixation plate 2 does not need to be particularly emphasized.

[0046] When performing fracture fixation surgery using the fracture fixator provided by this invention, a fixation pin 1 can generally be implanted into a small bone block through a minimally invasive incision and connected to fix the fracture site. Because the diameter of the fixation pin 1 can be made relatively small, iatrogenic damage to the bone block (such as splitting) can be minimized, achieving precise reduction and temporary fixation of the fracture. Once the enlarged portion 5 on the fixation pin 1 is in close contact with the cortical surface of the bone block, the fixation pin 1 is broken along the breakable portion 6 and removed, leaving only the enlarged portion 5 embedded in the fixed bone block, minimizing implant residue. Depending on the size and shape of the bone block, at least one fixation pin 1 can be implanted at a selected location.

[0047] During the procedure, the fixation plate 2 is pre-bent in the thickness direction according to the anatomical curvature of the fracture site to ensure that the fixation plate 2 can conform to the bone surface to the greatest extent. The groove 8 of the fixation plate 2 is then placed over the implanted enlargement 5. For example, a lag screw is used to fix the fixation plate 2 to the main bone block through the first fixation hole 71 on the fixation plate 2. During the tightening of the lag screw, the fixation plate 2 generates compressive stress on the enlargement 5, thereby achieving stable reduction and fixation of the fracture site.

[0048] Furthermore, the diameter of the needle body 4 is 0.5-1.5 mm. According to one embodiment of this application, the selection of the diameter of the fixing needle 1 is related to the strength of the material. Under the condition of ensuring strength, it is best to choose a smaller diameter.

[0049] Furthermore, the maximum width of the enlarged portion 5 on the fixing pin 1 is 2.0-2.5mm. According to an embodiment of this application, the enlarged portion 5 is not an ideal spherical shape, but can maintain a smooth outer surface, such as an olive shape or an ellipse shape. At the same time, the enlarged portion 5 matches the groove 8 on the fixing plate 2 so that it can be fixed by the fixing plate 2.

[0050] Another consideration is that the breakable portion 6 should be tightly attached to the surface of the enlarged portion 5. This breakable portion 6 can be achieved by creating a groove in the needle body 4, or by making the diameter of the breakable portion 6 smaller than the diameter of other parts of the needle body 4. It is also necessary to ensure that the breakable portion 6 does not break when the fixed needle 1 is inserted. The design of the breakable portion 6 can be achieved through physical subtraction and structural design in existing technologies. For example, at a predetermined breakage position on the needle body 4, a ring-shaped "V" or "U" shaped groove can be machined using turning or grinding processes, significantly reducing the cross-sectional area at that point and making it the weakest point on the entire needle body 4, thus allowing it to break at that location. Existing technologies also provide other methods to make a needle-like object easily breakable at a certain location.

[0051] Furthermore, the distance between the enlarged portion 5 on the fixation pin 1 and the pin tip 3 is 20-30 mm. According to one embodiment of this application, this length needs to take into account the scenario in which the fixator is applicable, and can be measured and trimmed during the operation. Therefore, the distance between the enlarged portion 5 and the pin tip needs to be determined according to the fracture site.

[0052] Furthermore, the fixation plate 2 also includes a second fixation hole 72. The second fixation hole 72 is used to place temporary fixation needles in the early stage of surgery to position the fixation plate 2; preferably, the first fixation hole 71 is provided with internal threads.

[0053] Furthermore, the groove 8 can be an elongated groove that can accommodate the enlarged portions 5 on multiple fixing pins 1.

[0054] In another embodiment of the present invention, such as Figure 4 As shown, there are multiple grooves 8, which are distributed and independently arranged. Each groove 8 is matched and presses against the enlarged part 5 of a fixing needle 1. The position of each groove 8 can be determined in advance according to the position of the fixing needle 1 to be inserted after the surgical plan is determined.

[0055] Application Example 1

[0056] For fixation of small bone fragments in fractures of the posterior wall of the acetabulum and the coronoid process of the ulna, see [reference]. Figure 5 .

[0057] This application example aims to illustrate how the fracture fixator of the present invention can be used to achieve strong and stable fixation of small bone fragments (such as bone fragments of the posterior wall of the acetabulum and the coronoid process of the ulna) that are difficult to fix in the intra-articular and near-articular areas.

[0058] A. Indications and Preoperative Preparation

[0059] Indications: Small avulsion or split fractures involving articular surfaces or requiring strong fixation.

[0060] Posterior wall fracture of the acetabulum: When the volume of the posterior wall bone fragment is less than 2cm × 2cm and cannot be effectively held by traditional screws or locking plates.

[0061] Ulnar coronoid process fracture: Regan-Morrey classification type II or above (small bone fragments).

[0062] The diameter of the fixing pin 1 used in this application example is 0.8mm, 1.0mm, 1.2mm or 1.5mm, and the maximum diameter of the enlarged part is 2.0mm;

[0063] The thickness of fixation plate 2 is 1.5mm, and it is pre-bent to an arc of 15 to 25 degrees (depending on the fracture site).

[0064] This application example also requires terminal fixation screws: cortical bone screws (2.7 mm in diameter) or locking screws (2.4 mm in diameter).

[0065] B. Surgical Procedure

[0066] Step S1: Exposure and Reset

[0067] S11. Position and Approach: The patient is placed in a lateral or supine position. The modified Kocher-Langenbeck approach (for the posterior wall of the acetabulum) or the anterior elbow approach (for the coronoid process of the ulna) is used.

[0068] S12. Fracture reduction: Under fluoroscopy, the small bone fragments are precisely anatomically reduced by direct or indirect manipulation.

[0069] Step S2: Insertion of the fixing pin

[0070] S21. Needle insertion: Insert a fixation needle 1 of any diameter (0.5-1.5mm) into the bone fragment along its long axis or stabilizing axis, depending on the size of the fracture fragment.

[0071] S22. Depth control: Ensure that the needle tip 3 penetrates the bone block and is anchored in the cancellous or cortical bone of the main bone block, while ensuring that the 2.0 mm enlargement 5 structure is in close contact with the cortical surface of the bone block to provide initial pull-out resistance.

[0072] S23. Breaking: Break the needle body 4 along the pre-set easy-break section 6 and remove it, leaving only the enlarged part 5 to be embedded in the fixation bone block, thus minimizing the residual implant. Depending on the size and shape of the bone block, 1 to 3 fixation needles 1 can be implanted.

[0073] Step S3: Locking the press-fit fixing plate 2

[0074] S31. Shaping of Fixation Plate 2: The 1.5mm thick multidimensional press-fit fixation plate 2 is precisely pre-bent according to the bone surface morphology, either externally or using a special shaping tool.

[0075] S32. Press fitting: Attach the fixation plate 2 to the fracture site, aligning its continuous spherical groove 8 with and covering all implanted fixation pins 1.

[0076] S33. Compression and Locking: Insert a 2.7mm or 3.5mm diameter lag screw through the first fixation hole 71 on the fixation plate 2. After drilling the first fixation hole, routinely insert another cortical bone screw or locking screw.

[0077] When the tension screw is tightened, the fixing plate 2 exerts a strong pressing force on the fixing pin 1 below, causing the enlarged part 5 and the groove 8 to form a ball-and-socket lock.

[0078] This compression not only tightly fixes the enlarged part 5, but also provides axial or eccentric compression (Lag Effect) to the fracture fragments, enhancing the stability of the fracture ends.

[0079] Step S4: Final Inspection

[0080] Intraoperative fluoroscopy confirmed satisfactory reduction, complete locking of the enlarged portion 5, and good fit between the fixation plate 2 and the bone surface.

[0081] Application Example 2

[0082] The grooves 8 at one end of the fixing plate 2 of the present invention are multiple dispersed and independent, as shown in the reference. Figure 4 The positions of the grooves 8 on the fixation plate 2 can be determined before fabricating the fixation plate, based on imaging data analysis of the locations requiring fixation, i.e., the locations where multiple fixation pins 1 need to be inserted. During surgery, each groove 8 is matched and pressed against the enlarged portion 5 of one fixation pin 1.

Claims

1. A fracture fixation device, characterized in that, Includes a fixing pin (1) and a fixing plate (2); The fixing needle (1) includes a needle body (4) with a needle tip (3) at one end. A bulging part (5) is provided on a section of the needle body near the needle tip (3). A foldable part (6) is provided on the side of the needle body (4) away from the needle tip (3) of the bulging part (5). The fixing plate (2) has a fixing hole (7) at one end and at least one groove (8) at the other end that matches the enlarged part (5) on at least one fixing pin.

2. The fracture fixation device according to claim 1, characterized in that, The maximum width of the enlarged portion (5) is 2.0-2.5 mm.

3. The fracture fixation device according to claim 2, characterized in that, The distance between the enlarged portion (5) and the tip of the needle is 20-30 mm.

4. The fracture fixation device according to claim 1, characterized in that, The diameter of the needle body (4) is 0.5-1.5 mm.

5. The fracture fixation device according to claim 1, characterized in that, The fixing hole (7) includes a first fixing hole (71) and a second fixing hole (72).

6. The fracture fixation device according to claim 5, characterized in that, The first fixing hole (71) is provided with an internal thread.

7. The fracture fixation device according to claim 1, characterized in that, The groove (8) is an elongated groove for accommodating the enlarged portions (5) on multiple fixing pins.

8. The fracture fixation device according to claim 1, characterized in that, The groove (8) has multiple grooves, which are arranged independently and distributed separately. Each groove is matched with the enlarged part (5) of a fixing needle.

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