Absorbable scaffolds that reshape the dura mater during dural repair

Abstract

The present invention discloses an absorbable scaffold for shaping the dura mater during dural repair. The absorbable scaffold is a resilient mesh structure with multiple gaps that, after softening by heating, conforms to the inner surface and cross-section of the bone flap and, after cooling, settles to the curvature of the inner surface and cross-section of the bone flap. This absorbable scaffold for shaping the dura mater during dural repair effectively addresses the problem of large epidural gaps caused by improper dural suturing, achieving watertightness requirements.

Description

Technical Field

[0001] The present invention relates to an absorbable stent for shaping the dura mater during dura mater repair. Background Art

[0002] A sutureless dural patch provides a reliable and rapid method for watertightly repairing dural defects. The patch generally covers the dural defect and a 1-2 cm margin of the dura beyond the defect. This method prevents bleeding from the dura, skull, muscles, and scalp from entering the residual cavity after resection of the brain lesion, the subarachnoid space, or the subdural space. To achieve watertightness, the material should not be removed from the dural margin after being firmly bonded to the patch to adjust its position. When using a dural patch that requires sutures, the edges of the patch should be sutured continuously or with closely spaced interrupted sutures to achieve watertightness. Furthermore, after surgery, when intracranial pressure (the pressure on the subdural brain tissue) rises, the curvature of the dura should approximate the curvature of the medial surface of the repositioned bone flap (in other words, the dura should be fully adherent to the medial surface of the repositioned bone flap). Achieving this latter effect can reduce epidural hemorrhage. The purpose of the above operation is to avoid (reduce) the postoperative retention of epidural and subdural drainage tubes, and the overall effect is to promote the patient's rapid recovery after surgery.

[0003] The common practice to achieve the latter operation effect is to directly cut off a part of the dura mater repair material under visual inspection, and then cover (or suture) the edge band of the repair material on the edge band of the dura mater, or appropriately lift the central point of the dura mater repair material, while ensuring that all the edge bands of the dura mater are covered by the repair material (tension-free adjacent to suture), and then drill multiple holes in the bone flap, pass the sutures reserved on the dura mater through the holes on the bone flap, retract and fix the bone flap, and tie the thread suspending the dura mater to eliminate the epidural space.

[0004] In the case of visual inspection, the following situations may often occur: 1. Too much dural repair material is cut, resulting in too tight sutures. After the repair is completed, the curvature of the dural membrane is too large (close to horizontal), resulting in a large epidural space (such as Figure 1 2. Too little material is cut, or the center point of the material is raised too high during repair, resulting in too much dura mater redundancy after the repair (such as Figure 2 (As shown) (When the central point of the dura mater is lifted, the tent formed by the dura mater is too high). Although the dura mater is suspended, the epidural space is still large.

[0005] Therefore, it is necessary to design an absorbable stent that can shape the dura mater during dura mater repair to improve the above-mentioned defects. Summary of the Invention

[0006] The purpose of the present invention is to provide an absorbable stent for shaping the dura mater during dura mater repair, so as to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above-mentioned purpose, the present invention provides an absorbable stent for shaping the dura mater during dura mater repair. The absorbable stent is an elastic mesh structure with multiple gaps that is softened by heating and then shaped to the inner surface and cross-section of the bone flap. After cooling, it is shaped according to the curvature of the inner surface and cross-section of the bone flap.

[0008] Preferably, the heating softening temperature of the absorbable stent is 60-65°.

[0009] Preferably, the absorbable stent comprises a plurality of rod-shaped filaments distributed radially and a plurality of ring-shaped filaments distributed in a quasi-concentric ring pattern, wherein each rod-shaped filament is connected to each ring-shaped filament to form a spider web structure, wherein the pores of the spider web structure are spaced-apart gaps, and the ends of the plurality of rod-shaped filaments that are close to each other are connected to the ring-shaped filament with the smallest diameter or are connected together after passing over the ring-shaped filament with the smallest diameter.

[0010] Preferably, the included angles between each two adjacent rod-shaped wires are equal, and the spacing between each two adjacent ring-shaped wires is equal.

[0011] Preferably, the number of the rod-shaped wires is four, six or eight, and the distance between each two adjacent ring-shaped wires is 5 mm to 10 mm.

[0012] Preferably, the rod-shaped wire and the ring-shaped wire are sheet-like structures with a width of 1-3 mm and a thickness of 0.5-2 mm.

[0013] Preferably, the entire absorbable stent is made of pure oligomeric L-lactic acid material.

[0014] Compared with the prior art, the absorbable stent for shaping the dura mater during dura mater repair of the present invention has the following beneficial effects:

[0015] (1) The dura mater is suspended by using an elastic absorbable stent with a mesh structure that is heated and softened and can be shaped according to the inner surface of the flap and the cross-section of the bone flap. The curvature of the dura mater after being suspended can be close to the curvature of the inner surface of the bone flap, effectively solving the problem of large extradural space caused by improper suturing of the dura mater in the past and meeting the watertightness requirement; leaving a gap can facilitate the rapid adjustment of the position of the suture-free dura mater patch under the absorbable stent outside the absorbable stent or sew the patch on the dura mater. For the dura mater patch that needs to be sutured, the dura mater, dura mater patch and rod-shaped wire can be directly sutured together at the intersection of the three and the suture can be tied and fixed on the rod-shaped wire or ring-shaped wire to suspend the dura mater. There is no need to drill a hole in the bone flap for suspension, and the dura mater repair also meets the watertightness requirement.

[0016] (2) The absorbable stent is made of oligomeric L-lactic acid material, which has excellent mechanical properties, including shape memory ability. Oligomeric L-lactic acid material is a thermoplastic crystalline polymer. It can be softened by heating and can be manually shaped. It can be quickly shaped into a shape similar to the bone flap according to the curvature of the inner surface of the bone flap, and guide the cutting of dura mater repair materials to maximize the closure of the epidural space. Oligomeric L-lactic acid material can be dissolved in the body by simple hydrolysis, has good biocompatibility, can be quickly absorbed in the body, has no side effects, and is low in cost.

[0017] The present invention will become more apparent from the following description taken in conjunction with the accompanying drawings, which are used to illustrate embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Improper trimming of the dura mater material results in overtightening of the sutures, which increases the curvature of the dura mater and creates a large gap between the dura mater and the bone flap.

[0019] Figure 2 This is an image showing improper trimming of the dura mater, which leads to epidural hemorrhage and hemorrhage in the residual brain cavity.

[0020] Figure 3 This is a schematic diagram of an embodiment of the absorbable stent for shaping the dura mater during dura mater repair according to the present invention.

[0021] Figure 4 for Figure 3 Schematic diagram of the absorbable scaffold being shaped along the bone flap.

[0022] Figure 5 For the general Figure 4 Schematic diagram after the excess part is cut off.

[0023] Figure 6 This is a schematic diagram of another embodiment of the absorbable stent for shaping the dura mater during dura mater repair according to the present invention.

[0024] Figure 7 This is a schematic diagram of another embodiment of the absorbable stent for shaping the dura mater during dura mater repair according to the present invention.

[0025] Figure 8 This is a schematic diagram of another embodiment of the absorbable stent for shaping the dura mater during dura mater repair according to the present invention.

[0026] Figure 9 This is a schematic diagram of another embodiment of the absorbable stent for shaping the dura mater during dura mater repair according to the present invention.

[0027] Explanation of the accompanying reference numerals: absorbable stent 1, rod-shaped wire 11, ring-shaped wire 12, reserved gap 1a, bone flap 100, and protruding portion 200. Implementation Method

[0028] Embodiments of the present invention will now be described with reference to the accompanying drawings, wherein like reference numerals represent like elements throughout the several views.

[0029] Please refer to Figure 3-8 The absorbable scaffold 1 used to shape the dura mater during dural repair is entirely made of pure oligomeric L-lactic acid. After being heated and softened, the absorbable scaffold 1 conforms to the inner surface and cross-section of the bone flap 100 and, after cooling, takes its shape according to the curvature of the inner surface and cross-section of the bone flap 100. The absorbable scaffold 1 has a resilient mesh structure with multiple interspaces 1a. The softening temperature of the absorbable scaffold 1 is 60-65°C, making it easy to manually manipulate during surgery.

[0030] The absorbable stent 1 specifically includes a plurality of rod-shaped filaments 11 distributed radially and a plurality of ring-shaped filaments 12 distributed in a concentric ring pattern. Each rod-shaped filament 11 is connected to each ring-shaped filament 12 to form a spider web structure. The pores of the spider web structure are spaced-apart gaps 1a. The ends of the plurality of rod-shaped filaments 11 that are close to each other are all connected to the ring-shaped filament 12 with the smallest diameter, or the ends of the plurality of rod-shaped filaments 11 that are close to each other pass over the ring-shaped filament 12 with the smallest diameter and then converge and connect together (e.g., Figure 7 ).

[0031] The included angles between any two adjacent rod-shaped wires 11 are equal, and the distances between any two adjacent ring-shaped wires 12 are equal.

[0032] The number of the rod-shaped wires 11 is four, six (eg Figure 5 ) or eight (such as Figure 6 ), the spacing between each two adjacent annular wires is 5mm-10mm. During surgery, a suitable shape can be selected according to the size of the bone flap 100 and the curvature of the inner surface of the bone flap 100. The goal is to place the absorbable stent 1 stably on the dura mater and facilitate watertight suturing of the dura mater and suspending the dura mater on the absorbable stent 1. The rod-shaped wire 11 and the annular wire 12 are sheet-like structures with a width of 1-3mm and a thickness of 0.5-2mm. During surgery, a suitable shape can be selected according to the size of the bone flap 100 and the curvature of the inner surface of the bone flap 100. The goal is to make it as thin as possible and to ensure sufficient support for the absorbable stent 1.

[0033] The implementation method is as follows:

[0034] 1) After heating the absorbable stent 1 to 60-65°, place it on the inner surface of the bone flap 100 cut from the bone window of the head, press the absorbable stent 1 toward the inner surface of the bone flap 100 so that the absorbable stent 1 is completely in contact with the inner surface of the bone flap 100, and bend the absorbable stent 1 at the cross section of the bone flap 100 so that the absorbable stent 1 is completely in contact with the cross section of the bone flap 100 (free edge). After the absorbable stent 1 cools down, it is shaped according to the curvature of the inner surface and cross section of the bone flap. Cut off the excess 200 of the absorbable stent 1 that extends beyond the cross section of the bone flap 100 with scissors.

[0035] 2) Take a template, similar to a sterile colored surgical drape, perform a predictive trim, and then place it over the dura mater defect exposed at the cranial bone window. Remove the absorbable scaffold 1 from the bone flap 100 and place it within the cranial bone window. Lift the trimmed template through the absorbable scaffold 1 at the center of the cranial bone window to the height indicated by the absorbable scaffold 1. Inspect the trimmed template for proper size. If not, repeat this step. If so, remove the absorbable scaffold 1 and trimmed template from the cranial bone window.

[0036] 3) Select the appropriate size (specification) of dura mater repair material according to the template with satisfactory trimming shape, and trim the dura mater repair material.

[0037] 4) Place the trimmed dura mater repair material to a satisfactory size and shape on the dura mater defect as indicated by the surgical film.

[0038] 5) Place the absorbable stent 1 within the bone window. Starting from the center of the bone window, create a tension-free dural suspension thread through the dura mater by traversing the dura mater. Tie the thread through the remaining gap 1a and quickly suspend the dural patch material from the center to the absorbable stent 1. If the dural patch material is already firmly attached to the dura mater, the suspensory force should be adequate. For dural patches requiring suturing, after suspensing the desired curvature of the dura mater, perform continuous or intermittent sutures between the dura mater and the patch material. Alternatively, the dura mater, patch, and the rod-shaped wires 11 or loops 12 of the absorbable stent 1 can be tied together, creating both a suspension and a watertight suture.

[0039] 6) If the dura mater repair is not watertight, dura mater glue can be applied to the gap in the dura mater through the gap 1a of the absorbable stent 1.

[0040] 7) Bone flap 100 is routinely returned to the bone window on the head.

[0041] Literature (Shen Xiaoqing and Li Shaoping. Study on the Degradation Properties of Oligomeric L-Lactic Acid) suggests that oligomeric L-lactic acid (OLLA) possesses excellent mechanical properties, including shape memory. OLLA is a thermoplastic crystalline polymer. When the glass transition temperature (60-65°C) is exceeded, the entire molecular chain of the polylactic acid (PLA) begins to move, exhibiting viscous flow properties. At this point, the stent easily deforms, allowing for manual shaping. It can be quickly molded to a similar shape to the internal curvature of the bone flap, guiding the cutting of dural repair materials to maximize epidural closure (i.e., bone window). OLLA dissolves in the body through simple hydrolysis, exhibiting excellent biocompatibility, meaning it is rapidly absorbed, has no side effects, and is low-cost. Strips (1.5 mm × 3 mm × 25 mm) made of OLLA have a strength of up to 45.3 MPa. The absorbable stent 1 is made of oligomeric L-lactic acid (PLA). By optimizing the thickness, width, and size of the reserved gaps in the filaments, its overall strength is significantly greater than the human systolic blood pressure limit (39.9 kPa). The pressure of epidural hemorrhage, whether venous or arterial, should be below this limit. Therefore, it can maintain a similar curved shape to the bone flap for a long time, effectively and stably supporting the dura mater, preventing its collapse and enabling rapid, watertight closure. The reserved gaps 1a in the absorbable stent 1 allow sutures to be passed through the dura mater and tied to the rod-shaped filaments 11 to suspend the dura mater, eliminating the need to drill holes in the bone flap.

[0042] If the patient prefers an absorbable material, the present invention provides a similar stent made of stainless steel. After completing most of the procedure, the suspending wires are cut with a scalpel, and the dural suspension wires are tied to the bone hole in the center of the bone window according to traditional methods. This stent can be sterilized and reused repeatedly. The rod-shaped wire 11 and the loop-shaped wire 12 of the stent can be cylindrical, with a diameter of 1 mm.

[0043] In other embodiments, Figure 9 The mesh structure of the absorbable stent 1 can be a mesh structure of other types except a spider web, and the mesh structure is composed of a plurality of rod-shaped filaments 11 crisscrossed.

[0044] The present invention has been described above in conjunction with the best embodiments, but the present invention is not limited to the embodiments disclosed above, but should cover various modifications and equivalent combinations based on the essence of the present invention.

Claims

1. An absorbable stent for shaping the dura mater during dural repair, characterized by: The absorbable stent is a resilient mesh structure with multiple gaps that is formed after being heated and softened and then conforms to the inner surface and cross section of the bone flap and is fixed to the curvature of the inner surface and cross section of the bone flap after being cooled. The heating softening temperature of the absorbable stent is 60-65°; The absorbable stent includes a plurality of rod-shaped filaments distributed in a radial pattern and a plurality of ring-shaped filaments distributed in a quasi-concentric ring pattern. The rod-shaped filaments are connected to the ring-shaped filaments to form a spider web structure. The pores of the spider web structure are space gaps. The ends of the plurality of rod-shaped filaments that are close to each other are connected to the ring-shaped filament with the smallest diameter or converge and connect together after crossing the ring-shaped filament with the smallest diameter.

2. The absorbable stent for shaping the dura mater during dura mater repair according to claim 1, characterized in that: The included angles between any two adjacent rod-shaped wires are equal, and the distances between any two adjacent ring-shaped wires are equal.

3. The absorbable stent for shaping the dura mater during dura mater repair according to claim 2, characterized in that: The number of the rod-shaped wires is four, six or eight, and the distance between each two adjacent ring-shaped wires is 5 mm to 10 mm.

4. The absorbable stent for shaping the dura mater during dura mater repair according to claim 1, characterized in that: The rod-shaped wire and the ring-shaped wire are sheet-like structures with a width of 1-2 mm and a thickness of 0.5-2 mm.

5. The absorbable stent for shaping the dura mater during dura mater repair according to claim 1, characterized in that: The entire absorbable stent is made of pure oligomeric L-lactic acid material.

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