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CA-3094833-C - FORMABLE MESH FOR CORRECTING BONE DEFECTS

CA3094833CCA 3094833 CCA3094833 CCA 3094833CCA-3094833-C

Abstract

Formable mesh implants suitable for correcting bone implants are disclosed. A formable mesh may include a plurality of node plates that define a lattice, where connecting arms extend from each node plate. Each connecting arm associated with a given node plate connects with a plurality of adjacent connecting arms at a respective intermediate connection region, such that each connecting arm associated with the given node plate is connected to a different intermediate connection region, and such that neighboring node plates are indirectly connected through multiple connecting arms. At least a subset of the node plates may respectively include a screw-receiving aperture, and the intermediate connection regions may be absent of screw-receiving apertures. In another example embodiment, a formable mesh is disclosed in which each connecting arm of a given node plate connects with an adjacent node plate, where adjacent node plates are directly connected through at least two connecting arms.

Inventors

  • Oleh ANTONYSHYN
  • Glenn Edwards
  • James MAINPRIZE

Assignees

  • Sunnybrook Research Institute

Dates

Publication Date
20260505
Application Date
20190405
Priority Date
20180406

Claims (20)

  1. THEREFORE WHAT IS CLAIMED IS: 1. A formable implant for skeletal fixation or correction of skeletal defects, the formable implant comprising a formable mesh, the formable mesh comprising: a two-dimensional lattice comprising a plurality of node plates interconnected via a plurality of intermediate connection regions, such that adjacent node plates in the two-dimensional lattice are indirectly connected through a respective intermediate connection and are absent of direct connection; each intermediate connection region being connected to a plurality of adjacent node plates via respective connection arms, the connection arms radiating from the intermediate connection region in a pinwheel configuration, such that when a compressive or tensile force is applied to the formable mesh: each intermediate region undergoes rotation; and nearest neighbour intermediate connection regions rotate with opposing rotational sense, such that the node plates predominately undergo translation.
  2. 2. The formable implant according to claim 1 wherein the area of a given intermediate connection region is smaller than the area of each adjacent node plate.
  3. 3. The formable implant according to claim 1 wherein each node plate comprises an elongate member.
  4. 4. The formable implant according to claim 3 wherein the elongate members that are adjacent to one another are oriented at different angles.
  5. 5. The formable implant according to claim 4 wherein the elongate members that are adjacent on one another are perpendicular.
  6. 6. The formable implant according to any one of claims 3 to 5 wherein each elongate member comprises a least one pair of slots defined therein to permit deformation thereof, wherein each pair of slots is aligned along a different respective axis.
  7. 7. The formable implant according to any one of claims 1 to 6 wherein nearestneighbor node plates are connected through two intermediate connection regions.
  8. 8. The formable implant according to any one of claims 1 to 7 wherein at least one 23 Date Rei;ue/Date Received 2023-12-07 connecting arm has a width that varies over a longitudinal extent thereof.
  9. 9. The formable implant according to any one of claims 1 to 8 wherein a width of at least one connecting arm initially increases towards a maximum width as the connecting arm extends from its respective node plate, and then decreases as the connecting arm extends further to its respective intermediate connection region.
  10. 10. The formable implant according to any one of claims 1 to 9 wherein each node plate has a respective screw-receiving aperture.
  11. 11. The formable implant according to any one of claims 1 to 9 wherein each node plate within a first subset of node plates has a respective screw-receiving aperture, and wherein each node plate within a second subset of node plates is absent of a screw-receiving aperture.
  12. 12. The formable implant according to any one of claims 1 to 9 wherein each node plate within a first subset of node plates has a respective screw-receiving aperture, and wherein each node plate within a second subset of node plates has a respective additional aperture defined therein, wherein the diameters of the additional apertures are smaller than the diameters of the screw-receiving apertures.
  13. 13. The formable implant according to claim 12 wherein the diameters of the additional apertures are suitable for inserting a surgical suture therethrough.
  14. 14. The formable implant according to claim 12 wherein the plurality of node plates comprises a third subset of node plates that are absent of apertures.
  15. 15. The formable implant according to any one of claims 1 to 14 wherein an area fill factor of the formable mesh is at least 0.4.
  16. 16. The formable implant according to any one of claims 1 to 14 wherein an area fill factor of the formable mesh is at least 0.5.
  17. 17. The formable implant according to any one of claims 1 to 14 wherein an area fill factor of the formable mesh is at least 0.6.
  18. 18. The formable implant according to any one of claims 1 to 17 wherein a thickness 24 Date Rei;ue/Date Received 2023-12-07 of the formable mesh spatially and repeatably varies over each unit cell of the lattice.
  19. 19. The formable implant according to any one of claims 1 to 17 wherein a thickness of the formable mesh spatially varies over two or more unit cells of the lattice.
  20. 20. The formable implant according to any one of claims 1 to 19 further comprising one or more solid regions that are connected to, and extending beyond, the formable mesh.

Description

FORMABLE MESH FOR CORRECTING BONE DEFECTS BACKGROUND 5 The present disclosure relates to implants for correcting bone defects. The surgical repair of a defect of the skull or facial bones can be a technically difficult, laborious and time-consuming procedure. Accurate restoration of the missing anatomy is particularly challenging. The recent adaptation of computer assisted design and rapid prototyping technology is known to dramatically increase efficiency 10 and improve outcomes. Provided that the defect is stable, clearly defined and well visualized prior to surgery, computer modeling can be employed to generate a virtual 3D model of a patient-specific implant. Titanium mesh has proven to be effective clinically in the reconstruction of non-load-bearing defects of the skull and facial bones (Kuttenberger and Hardt, J. 15 CranioMaxfac. Surg., 2001; Schipper et al., Eur. Arch. Otorhinolaryngol., 2004). The mesh provides a stable, permanent, biocompatible reconstruction which is well tolerated, even when in direct contact with paranasal sinuses. Titanium is the most biocompatible metal and is known to generate a minimal inflammatory response when implanted. Titanium becomes osseointegrated after implantation and is well 20 tolerated even in a contaminated field. Due to its non-ferromagnetic properties, titanium is compatible with magnetic resonance imaging, and generates minimal artifacts in magnetic resonance imaging (MRI) images. CT (computed tomography) artifact associated with titanium mesh is also negligible and postoperative visualization of structures adjacent to titanium mesh is unobstructed. Titanium mesh 25 is exceptionally versatile under a variety of clinical scenarios and can be readily adapted to virtually any non-load bearing craniofacial defect. The mesh pattern is porous, allowing free drainage of body fluids and minimizing complications associated with fluid retention in closed spaces (hematoma, seroma, etc.). The mesh is partially transparent, facilitating visualization of underlying structures through the 30 mesh intraoperatively. Most importantly, titanium meshes are readily deformable. They are specifically designed to allow shaping into a three-dimensional construct, which can be done manually or using a mold system. They can be further trimmed to 1 Date Rei;ue/Date Received 2023-12-07 any required size for implantation. Conventional mesh designs also provide multiple locations for screw fixation. Despite the aforementioned benefits of titanium meshes, conventional mesh designs have a number of associated drawbacks. Some of these are technical, 5 posing challenges for the surgeon during intraoperative preparation of the implant, while some can have an adverse effect on patient outcomes and are far more significant. For example, the manual shaping of a conventional titanium sheet into a three-dimensional shape can be challenging. The difficulty increases with the complexity of surface topography and underlying anatomy. Contouring over more 10 defined regions with acute angles results in loss of surface fidelity and buckling of titanium mesh connecting arms. Furthermore, the trimming of conventional meshes necessarily results in a corrugated implant margin with irregular sharp barbs. These can lacerate or impinge abutting soft tissues and potentially restrict mobility of specific soft tissues such as extraocular muscles within the orbit. The implant edge is 15 often palpable and visible for patients with thin skin. Moreover, in order to be malleable, conventional mesh designs require large open space voids between connecting arms, resulting in a very low "fill factor'', the surface area ratio between solid mesh and void space. These voids pose three problems. Firstly, the presence of large voids precludes the use of meshes in areas 20 where soft tissue prolapse through mesh voids causes functional impairment. This is particularly important in orbital cavity reconstruction, where prolapse of intraorbital septa or extraocular muscles through the mesh can potentially result in extraocular muscle motility disorders. Secondly, adhesions between soft tissues on either side of the mesh unnecessarily complicate implant removal. The large voids allow soft 25 tissues on either side of the mesh to "fuse" during healing. If implant removal is required for some indication, the surgery requires extensive dissection and separation of the adhesions. Risks of inadvertent injury to surrounding structures, hemorrhage, etc. are significant. Finally, the open mesh pattern with large voids also predisposes to late erosion of overlying soft tissues with implant exposure. Titanium 30 mesh exposure is a recognized complication and has been documented in 16% of patients undergoing titanium cranioplasty. It has also been documented in dentoalveolar and maxillary reconstructions. This complication has particularly significant consequences, as it necessitates additional reconstructive surgery to remove the titanium