Sternal implant

Abstract

A sternal implant for implant into a body is provided. The implant includes an outer frame forming a structurally rigid portion. The outer frame includes a plurality of openings configured to accommodate sutures for affixing the outer frame to the body. The implant includes a central structure connected within the outer frame. The central structure includes a in the form of a layer having a construction including multiple channels. The filling portion is configured to allow for fluid drainage and tissue ingrowth of tissue generated by the body.

Description

[0001] STERNAL IMPLANT

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority from South African provisional patent application number 2024 / 06870 filed on 5 September 2024, which is incorporated by reference herein.

[0004] FIELD

[0005] This disclosure relates to prosthetic implants for a body. In particular, the disclosure relates to a sternal implant that is applicable to a variety of physiologies.

[0006] BACKGROUND

[0007] Chest wall tumours are tumours which may occur at a sternum or a rib cage of a patient. T umours in the chest wall may originate from tissues in the chest wall, which may include muscle, fat, blood vessels, nerves, cartilage, and bone. Chest wall tumours are more commonly either metastases or local invasion of an underlying adjacent tumour. In some cases, tumours of the chest wall may present in approximately 5% of all thoracic neoplasms. Furthermore, approximately 60% of primary chest wall tumours are malignant, which may be more likely in the extremes of ages, such as in young children and the elderly. Certain tumours may be present predominantly in one age group, such tumours being: Ewing sarcoma in children and young adults; chondrosarcoma in middle adults; and solitary plasmacytoma in older adults.

[0008] When presented with cases of tumours of the chest wall, the treatment plan may include surgery to resect the tumour. Resecting the tumour may include performing a wide resection of the area with up to three to five centimetre margins around the tumour. This may include the resection of portions of the ribs above and below the tumour. Other areas including adjacent muscle, underlying pleura, pericardium and lung may be resected if necessary.

[0009] After resection of the tumour, and potentially surrounding tissue, the area (such as chest wall or sternum) may require reconstruction. Reconstruction of the chest wall, or more particularly the sternum, after resection of the tumour requires that functional integrity of the body’s breathing mechanism remains constant (or as close as possible to normal functioning). Post-operative respiratory complications may occur in up to 24% of all complications observed. The reconstruction should ensure tissue coverage of underlying structures (bone, cartilage, etc.), and a prosthesis if implanted. The reconstruction may use other soft tissues of the body, such as muscle flaps (Pectoralis Major, Latissimus Dorsi, Rectus Abdominus) and other tissue flaps (Omentum, Thoracoepigastric Fasciocutaneous) to obtain tissue coverage to close a defect created by the resection or to cover an implant. The reconstruction should, preferably, be cosmetically pleasing. If possible, any sternum resection and / or reconstruction should try to preserve the manubrium and xiphoid if possible.

[0010] The preceding discussion of the background is intended only to facilitate an understanding of the present disclosure. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge in the art as at the priority date of the application.

[0011] SUMMARY

[0012] In accordance with an aspect of the disclosure there is provided a sternal implant for implant into a body, comprising: an outer frame forming a structurally rigid portion and including a plurality of openings configured to accommodate sutures for affixing the outer frame to the body; a central structure connected within the outer frame and including: a filling portion in the form of a layer having a construction including multiple channels configured to allow for fluid drainage and tissue ingrowth of tissue generated by the body.

[0013] The central structure may include at least one reinforcing rib spanning opposing sides of the outer frame.

[0014] The outer frame may include a longitudinal posterior curvature offset from a zero plane. The outer frame may include a transverse posterior curvature offset from a zero plane.

[0015] The posterior curvature may be offset from a zero plane between 0mm to 20mm to conform to an anatomy of the body.

[0016] The outer frame may be elongated having opposing longitudinal sides. The central structure may include at least two reinforcing ribs spanning between the longitudinal sides. The central structure may include four reinforcing ribs spanning between the longitudinal sides.

[0017] The central structure may have a height offset between an outer dimension of the outer frame with the central structure being of reduced height compared to the outer frame. The filling portion may be an additive manufactured filling pattern. The filling portion may be an additive manufactured gyroid filling pattern. The filling portion may have multiple sections of different filling pattern orientations. Sections with different filling pattern orientations may be defined by one or more reinforcing ribs.

[0018] The outer frame may include a flattened portion at one or both of a superior end and an inferior end. The superior end may be configured to be positioned proximate a manubrium of the body. The inferior end may be configured to be positioned proximate a xiphisternum of the body.

[0019] The outer frame may be unpolished to improve osteointegration. The plurality of openings may be polished to reduce abrasion of sutures. The plurality of openings may be chamfered suture holes. The openings of the plurality of openings may be spaced equidistant from each other.

[0020] A cross-section view of the outer frame may be an octagonal shape. A top view of the outer frame may be an octagonal shape.

[0021] The implant may be formed by additive manufacturing of a titanium-aluminium-vanadium alloy. The outer frame may be chamfered or filleted near an inner face and an outer face of the outer frame, providing a curved portion of the outer frame for tissue growth around the outer frame.

[0022] Embodiments of the technology will now be described, by way of example only, with reference to the accompanying drawings.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In the drawings:

[0025] Figure 1 is an isometric view of an example sternal implant according to aspects of the present disclosure;

[0026] Figure 2 is a three-dimensional side view of an example sternal implant according to aspects of the present disclosure;

[0027] Figure 3 is a top view of an example sternal implant according to aspects of the present disclosure without the filling portion shown;

[0028] Figure 4 is a top view of an example sternal implant according to Figure 3 illustrating a lattice filling portion;

[0029] Figure 5A is a front view of an example sternal implant according to aspects of the present disclosure;

[0030] Figure 5B is a back view of an example sternal implant according to aspects of the present disclosure;

[0031] Figure 6A is a side view of an example sternal implant according to aspects of the present disclosure;

[0032] Figure 6B is a sectioned side view of an example sternal implant according to aspects of the present disclosure;

[0033] Figure 7 is a sectioned front view of an example sternal implant illustrating internal features of an outer frame;

[0034] Figure 8 is an isometric view of an example sternal implant without reinforcing ribs;

[0035] Figure 9A is an illustration of an example mesh-like gyroid lattice structure of a filling portion; and,

[0036] Figure 9B is a sectional view of an example mesh-like gyroid lattice structure of a filling portion.

[0037] DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

[0038] A sternal implant for implant into a body is provided. The body may be that of a human patient or animal. The sternal implant may be an implant suitable for implant into the body during an operation. The implant may be manufactured using an additive manufacturing method, otherwise known as 3D-printing. Additive manufacturing may present a relatively low-cost surgical option. Additive manufacturing may be relatively quicker and easier to manufacture such implant that conventional manufacturing methods.

[0039] The implant may be designed to remain rigid and / or be sufficiently strong to protect underlying organs and prevent paradoxical movement. The implant may be manufactured from material that is substantially or completely inert. The implant may be biologically inert, such that the implant does not trigger an immune response of the body. The inertness may allow for in-growth of fibrous tissues surrounding the implant, throughout the implant, and to decrease a likelihood of infection. The implant material may be malleable to allow for conformation to the desired shape during manufacturing. For example, the implant may be required to be malleable to create rough textures and / or polished surfaces where required. However, the implant must be capable of being rigid once implanted. The implant may be radio-luminescent such that the implant is visually detectable in scans, such as x-rays.

[0040] The implant may be designed to represent a normal anatomy of a sternum. The implant may be designed according to a general shape with parameters that can be altered before manufacturing, thereby providing an individualized custom design process. For example, a height, a length and a width of the implant may be specified before manufacture. The design process may include additional parameters for manufacturing. In some examples, a range of implants of varying sizes may be manufactured, and an appropriately sized implant may be selected during surgery. The implant may include a low-profile curved design. The implant may provide for enhanced cosmetic results. The cosmetic results may be due to the low-profile curved design.

[0041] The implant may be usable for rigid reconstruction of an anterior chest wall during surgical resection of a sternal area. The implant may provide structural support, that allows for attachment to the surrounding rib cartilage, thereby preserving growth potential (that mainly originates in the costal rib cartilage). The implant may preserve the normal anatomy of an anterior sternal wall, while allowing enough movement of the chest wall to facilitate normal chest wall movement. Allowing enough movement is an essential requirement for normal breathing or respiratory effort.

[0042] An example sternal implant according to aspects of the disclosure is illustrated in Figures 1 to 9B. Aspects from any of the figures may be referred to throughout the disclosure. Figure 1 is an isometric view illustrating an example sternal implant 100 according to aspects of the disclosure. Figure 2 illustrates a three-dimensional side view of the same example implant 100. Figures 3 and 4 illustrate a top view of the example implant 100 with and without a filling portion 108 illustrated, respectively. Figures 5A and 5B illustrate a front view and a back view of the same example implant 100, respectively. Figure 6A illustrates a side view of the example implant 100. Figure 6B illustrates a side sectioned-view of section-line 131 through the implant 100 shown in Figure 3. Figure 7 illustrates a front sectioned-view of section-line 130 through the implant 100 shown in Figure 3. Figure 8 is an isometric view of an example sternal implant without reinforcing ribs. Figure 9A illustrates an example filling portion 108 of the example implant 100. Figure 9B is a sectional view of an example filling portion 108. An isometric view of the sternal implant 100 according to aspects of the disclosure is provided in Figure 1. The implant comprises an outer frame 102. The outer frame 102 forms a structurally rigid portion. The outer frame 102 may be a tubular body forming a frame along a periphery of the implant. The outer frame 102 may be hollow or solid. The outer frame 102 may be formed in an octagonal shape. The outer frame 102 includes a plurality of openings 104. The plurality of openings 104 may be holes extending through the outer frame 102. The plurality of openings 104 are configured to accommodate sutures for affixing the outer frame 102 to the body. The implant 100 also includes a central structure. The central structure may be connected to the outer frame 102. In some examples, the central structure may be formed within a boundary of the outer frame 102. The central structure comprises a filling portion 108. The central structure may comprise at least one reinforcing rib 106. The at least one reinforcing rib 106 may span between opposing sides of the outer frame 102. The filling portion 108 is in the form of a layer having a construction including multiple channels. The filling portion is configured to allow for fluid drainage and tissue ingrowth of tissue generated by the body. An additional three-dimensional side view of the implant 100 is shown in Figure 2.

[0043] The implant may be manufactured by an additive manufacturing method. The implant may be made from a titanium-aluminium-vanadium alloy. For example, the material may be a Ti 6AI-4V ELI (Titanium, 6% Aluminium, 4% Vanadium) alloy. The material may be of Grade 23. For example, the additive manufacturing method may be a process that utilises laser light to fuse layers of titanium powder together until a full three-dimensional model is obtained. The titanium powder layers, used during the manufacturing process, may be approximately 0.02 mm thick. The Ti 6AI-4V ELI alloy may be well suited for medical implants due to its material properties. The material properties may include high strength, low weight, good corrosion resistance, and a lower risk of rejection of the implant by the body. Additive manufacturing may produce implants with a rough or textured surface. Parts of the implant may be polished to provide a smooth surface, while other parts may be left unpolished. Parts of the implant may be sandblasted to increase adherence of granulating tissues of the body. The outer frame 102 and central structure, including the filling portion 108 and reinforcing ribs 106, may be manufactured as a single integrally formed component using the additive manufacturing method.

[0044] The plurality of openings 104 in the outer frame 102 may be spaced equidistant from each other. For example, the outer frame 102 may include thirty-six (36) openings. The plurality of openings may include chamfered edges 104A of the openings. The chamfered edges 104A may reduce damage or abrasion of sutures engaged with an opening. The openings 104 and chamfered edges 104A may be polished to reduce abrasion of sutures. The number and location of the plurality of openings may allow for the same design to be implanted into different physiologies of patients. By including a plurality of openings, a surgeon is not limited to a specified number of location or attachment points but can intraoperatively decide the appropriate openings to use. The design is made in such a nature that attachment points are not limited, and variability between patients may be catered for by using a different number of openings and locations of the openings for suturing.

[0045] The implant may be an elongated body with opposing sides. The opposing sides may include opposing longitudinal sides 122,123 as illustrated in Figure 3. In some examples, the longitudinal sides 122, 123 may be straight edges. The implant may further include at least one end portion. In some examples, the implant may include two end portions 120,124. The end portions may be transverse sides that are straight or flattened. In some examples, the opposing sides may refer to opposing end portions 120,124. Figures 5A and 5B illustrate two flattened end portions, an inferior end 120 and a superior end 124 of the implant, respectively. The implant may include a flattened end at the superior end 124. The superior end 124 may be configured for placement, during surgery, at an upper area of the sternum, for example, proximate a manubrium of the body. The implant may include a flattened end at the inferior end 120. The inferior end 120 may be configured for placement, during surgery, at a lower area of the sternum, for example, proximate a xiphisternum of the body. Flattened surfaces at the flattened ends 120,124 may improve bone attachment to the manubrium and xiphisternum. This is important in cases where the manubrium and xiphisternum are intended to be retained during surgery.

[0046] In the case where the implant 100 includes longitudinal sides, the longitudinal sides may include tapered portions. For example, a tapered portion 140A may extend from a central portion of the longitudinal side 122 to the inferior end 120. Similarly, a tapered portion 140B may extend from a central portion of the longitudinal side 123 to the inferior end 120. Analogous to the previously mentioned tapered portions, further tapered portions 141 A and 141 B may extend from central portions of the longitudinal sides 122,123 to the superior end 124. In some examples, the tapered portions 140A,140B,141A,141 B may form straight edges angled inwards towards the respective flattened ends 120,124. The tapered portions 140A,140B,141A,141 B may be curved edges.

[0047] The octagonal shape of the outer frame 102 may be formed by: central portions of the longitudinal sides 122,123, the tapered portions 140A,140B,141A,141 B, the flattened end at the inferior end 120, and flattened end at the superior end 124. A first opposing side of the outer frame 102 may be formed by the central portion of the longitudinal side 122 and corresponding tapered portions 140A.141A. Similarly, a second opposing sides of the outer frame 102 may be formed by the central portion of the longitudinal side 123 and corresponding tapered portions 140B.141 B. The at least one reinforcing rib 106 spans between any part of the first opposing side to the second opposing side. In some examples, a reinforcing rib may span between a portion of the outer frame 102 at the superior end 124 and a portion of the outer frame 102 at the inferior end 120. In further examples, the reinforcing rib 106 may span between either one of the longitudinal sides 122,123 and either of the superior end 124 and / or inferior end 120.

[0048] The central structure may include at least two reinforcing ribs 106A,106B as shown in Figure 3. In some examples, the implant may include four reinforcing ribs 106A,106B,106C,106D. The reinforcing ribs 106 may span between the longitudinal sides 122,123. Incorporating such reinforcing rib(s) 106 may enhance mechanical integrity and long-term durability of the filling portion. The reinforcing rib(s) 106 may include at least one chamfered or filleted edge such that a cross-section view of the reinforcing rib includes a tapered or rounded edge. In examples involving larger implant configurations or increased load-bearing demands, the inclusion of strategically placed reinforcing ribs may be required. The reinforcing ribs may serve to: distribute mechanical stress more evenly, reduce deformation under physiological loads, and / or improve overall structural resilience. The reinforcing rib integration may support better anatomical conformity and reduce the risk of implant fatigue over time. In some examples, the reinforcing rib may be a wedge-like or a flange like formation spanning between opposing sides of the outer frame. In some examples, the reinforcing rib is a bar-like formation, as depicted in Figures 1 to 4.

[0049] A top view of the implant 100 illustrating an example filling portion 108 is shown in Figure 4. The filling portion 108 may be configured to allow for tissue ingrowth of tissue generated by the body. Tissue in growth may help with securing the implant in the body. The filling portion 108 may be configured to allow for fluid management of the body. An example filling portion 108 structure is show in Figure 9A and 9B. The filling portion 108 may include varying shaped fill material. For example, the filling portion may include different orientations 108A,108B of a filling pattern. In some examples, the different filling patterns may be placed in sections separated by at least one reinforcing rib 106. In some examples, different patterns may be located adjacent each other. At least a part of the filling portion may be attached to an inner face of the outer frame 102, such that the filling portion and outer frame form a single integrally formed component.

[0050] In some examples, the central structure does not include any reinforcing rib 106 or ribs, as illustrated in Figure 8. The implant may comprise only the outer frame 102 and the filling portion 108. The filling portion 108 may include sections of different orientations 108A,108B of the filling pattern without reinforcing ribs dividing the different orientation 108A,108B filling patterns. In this example, either the outer frame 102 alone or the outer frame 102 combined with the filling portion 108 may be capable of withstanding forces subjected to the implant after implant into the body. The outer frame 102 may be unpolished. The unpolished surface to improve osteointegration (bone attachment to the implant) and tissue attachment. Improved osteointegration may improve the implants attachment to surrounding ribs of the chest wall, manubrium and xiphisternum. Natural porosity and micro-irregularity of the surface obtained by additive manufacturing may be beneficial for tissue adherence. The plurality of openings may be polished to provide a smoother surface finish. The polished surface may reduce abrasion of sutures placed within the openings.

[0051] Figure 6A illustrates a side view of the implant. Dimensions of the implant may be defined by a height 161 and a length 162. Furthermore, referring to Figure 5B, the implant may be defined by a width 164. The superior end may be defined by a superior width 165. Similarly, the inferior end may be defined by an inferior width. The outer frame may include a longitudinal posterior curvature 158. The longitudinal posterior curvature may be a centre longitudinal posterior curvature. The longitudinal posterior curvature 158 may be offset 160 from a zero plane 163. The longitudinal posterior curvature 158 is formed at a lower curved surface 159. A maximum height different between the lower curved surface 159 and the zero plane 163 may be the offset 160. In some examples, the longitudinal posterior curvature 158 may be a constant value. In some examples, the longitudinal posterior curvature 158 may be defined by a varying radius of curvature. In some examples, the curvature 158 may be zero, such that the offset is zero, i.e. the lower curved surface 159 is flat. If the offset is zero, the outer frame may be flat. In some examples, the implant may include a transverse posterior curvature offset from the zero plane, the transverse posterior curvature being perpendicular to the longitudinal posterior curvature (in an axis in-plane of Figure 6A). An example of a transverse posterior curvature 152 radius is illustrated in Figure 5A.

[0052] If the lower curved surface 159 is flat, i.e. the offset is zero, and a bounding box is drawn around the outer frame, the central structure and / or the filling portion may be completely within such bounding box. If the central structure and / or the filling portion is completely within the bounding box, a height offset between an outer dimension of the outer frame 102 and the centre structure may be defined. A filling offset may be included in the design. The filling offset is a height difference between a surface of the filling portion and the outer frame 102, when viewed from the side in Figure 6B. This may result in an inner surface 168 being of a height less than that of the outer frame. For example, the filling offset may be 0.45mm from the top and bottom, respectively. Therefore, the thickness of the filling portion may be 6.1mm in the example where the height of the implant is 7mm. These dimensions are not fixed and may be adjusted depending on each patient. The filling offset may ensure that the filling portion remains structurally embedded, preventing delamination or surface breach while allowing internal flexibility. The filling offset may prevent abrasion to the surrounding tissue that might be possible during the tissue ingrowth and fibrosis forming phase of healing. This may help to limit damage to surrounding tissue, blood vessels and organs.

[0053] Referring now to Figures 6B and 7, the outer frame 102 may be a hollow frame. The section view of Figure 6B is generated from section line 131 in Figure 3. The outer frame 102 may be tubular in cross-section. Due to the additive manufacturing method capable of producing the implant, the implant may have a wall 170 of varying thickness.

[0054] For example, a cross-section view of the outer frame is shown in Figure 7. The section view is generated from a section line 130 from Figure 3. The outer frame 102 may be octagonal in crosssection. The octagonal shape may be formed from a square shaped cross of the outer frame, and the edges may be chamfered and / or filleted to form round edges 103A,103B,150. Inner edges 150 are shown in Figures 6B and 7. The inner edges 150 may be chamfered and / or filleted. Therefore, the octagonal shape may comprise four faces of the square shape, and four edges between the faces. An inner surface 168 may be formed from an inside face of the outer frame. The centre structure may be attached to the inner surface of the outer frame. In some examples, the filling portion is directly attached to the inner surface 168. Therefore, the filling portion may be smaller in height than the outer frame such that the filling portion does not protrude outside the bounding box dimension of the implant as described above. The edges at the inner surface and an outer surface of the outer frame provide a curved portion of the outer frame for tissue growth around the outer frame. The edges may reduce irritation to the body and improve biocompatibility at the interface between the filling portion and surrounding tissue.

[0055] The implant may be manufactured to a default set of dimensions. In some examples, each dimension may be specified according to a customized set of parameters. The customizable dimension parameters may comprise anyone or more of: a length, a width, a height, an outer frame width, a longitudinal curvature offset, a transverse curvature offset, a superior end width, an inferior end width, a wall thickness, an opening diameter, an opening spacing, a number of openings, a number of reinforcing ribs, a thickness of reinforcing ribs, a filling portion type, a filling portion cell size, a filling offset, and, a filling portion thickness.

[0056] A set of default parameters may include: height of 7mm, length of 100mm, width of 50mm, outer frame width of 10mm, a wall thickness of 1mm, a longitudinal curvature offset of 7mm from the zero plane, zero transverse curvature offset, a superior end width of 30mm, an inferior end width of 23mm, a reinforcing rib thickness of 1 mm, four reinforcing ribs, and 36 openings in the outer rim. In these example default parameters, the longitudinal curvature offset of 7mm may refer to the offset 160. The ratio of the offset 160 to length 162 may be between 5mm to 10mm of offset per 100mm length of the implant, i.e. 5% to 10% of the length. In an example sternal implant provided, the ratio is 7mm offset for a 100mm in length implant, i.e. 7%. These are only default parameters and any combination that is manufacturable and suitable for an anatomy of the patient may be suitable.

[0057] The default parameters may cover a broad spectrum of standard anatomical presentations. However, modular sizing may be used to better address patient variability across clinical scenarios.

[0058] The outer dimensions of the implant may range between a height of 6mm to 12mm, a length of 50mm to 200mm, and a width of 40mm to 100mm. In some examples, should the design be extended toward the upper limits of these ranges, an additional curvature (the transverse curvature offset) along the horizontal plane may be incorporated. Adding an additional curvature may enhance anatomical conformity, particularly in cases requiring broader surface coverage or adaptation to complex topographies. Such additional curvature could improve implant integration, reduce edge lift, and support more natural biomechanical interfacing with surrounding tissues. The wall thickness may vary depending on specific needs of a patient. An example range for the wall thickness is 0.8mm to 1.4mm

[0059] An example illustration of the filling portion 108 is shown in Figure 9A. A sectional view of the outer frame and filling portion is illustrated in Figure 9B. The channels 109 of the filling portion may be a structured set of channels. The structured set of channels may be straight channels extending from one side of the filling portion to another side of the layer. In some examples, the channels may be a set of randomised channels. The channels may be a set of inter-weaving channels. The channels may be a set of inter-connected channels. In some examples, the channels may be curved channels. The curved channels may form a smooth surface between the channels. The smooth surface may be a geometrically continuous surface.

[0060] The filling portion 108 may have a lattice construction. The filling portion may be a mesh-like gyroid core. The gyroid core may be a Triply Periodic Minimal Surface. In some examples, the filling portion 108 may include a three-dimensional gyroid filling pattern, as shown in Figure 9 A and 9B. As shown in Figure 4 and 9A, the filling portion may include differing orientations of the filling pattern. The differing orientations 108A,108B may be in different areas of the filling portion. Each of the different orientations may include repeating patterns of channels. Figure 9A illustrates different areas within dash-lined boxes. A first area may include a mesh-like filling pattern in a horizontal orientation 108A. A second area may include a mesh-like filling pattern in a vertical orientation 108B. Any type of sets of channels, in different orientations, may be combined within the filling portion, such as a part of the filling portion being straight channels, some part of the filling portion being curved channels, and some part of the filling portion being a gyroid lattice construction, or another combination thereof. The channels may be designed to provide optimal fluid management and tissue ingrowth, while reducing damage to surrounding tissues.

[0061] In some examples, the filling portion may feature a consistent mesh and material density across all sections, ensuring uniform baseline mechanical properties. In other examples, the mesh of the filling portion may be intentionally varied across regions to optimize biomechanical performance. The multidirectional alignment may enhance the implant’s ability to withstand complex physiological loads by distributing stress along multiple axes. Each section of differently aligned mesh may contribute to load-sharing, reducing localized strain and improving overall structural resilience.

[0062] Default parameters for the central structure may include: a filling portion type of Triply Periodic Minimal Surface - Gyroid (sheet based gyroid lattice structure), a filling portion cell size of 2.5 mm, a reinforcing rib thickness of 0.4mm to 0.45mm, and a filling offset of 0.45mm. This configuration may yield a highly porous, interconnected lattice that spans a full internal volume of the implant, while maintaining a protective shell boundary.

[0063] The gyroid lattice may include a continuous curvature such that it lacks sharp edges, which allows the lattice to distribute mechanical loads evenly across all directions. Evenly distributing mechanical loads is ideal for sternum implants, which must endure respiratory motion, muscular tension, and post-surgical stress. Smooth transitions between reinforcing ribs and the filling portion may improve fatigues resistance, reduce stress concentrations, enhancing long-term durability under cyclic loading, which is especially important in thoracic applications. The approximately 2.5 mm filling portion cell size may support soft tissue migration and vascularization. The gyroid lattice curvature mimics natural extracellular matrices, promoting adhesion and cellular proliferation. The gyroid lattice may increase an internal surface area. The internal surface area may include a bioactive-coatings, such as hydroxyapatite, titanium oxide, or drug-eluting applications. While gyroid lattice structures are isotropic, their curvature can support capillary action, enhancing localized fluid transport, especially if paired with gradient porosity zones. From a clinical perspective, the varied filling portion architecture may positively influence tissue integration. The differential orientation may form microenvironments that facilitate cellular adhesion and directional tissue ingrowth, depending on the surrounding anatomical forces. The choice of filling portion may influence fluid management of the implant. Interstitial spacing and directional porosity of the mesh in the filling portion may support enhanced fluid exchange and fluid management.

[0064] Enhanced fluid management may limit the formation of a seroma or a haematoma and aide in exudate management. The filling portion may all for fluid to movement through the filling pattern and dissipate through the implant. The filling portion may allow for good fluid management early post-surgery for better tissue ingrowth and thus better implant integration in the body. Enhanced fluid management may further allow for tissue ingrowth to enhance incorporation of the implant into surrounding tissue. The natural porosity of the titanium additive manufacturing process together with creating an enhanced roughness of the outer frame assists in tissue integration. The titanium material offers a high strength to weight ratio, and using additive manufacturing techniques, it is possible to hollow out the implant and create the mesh like gyroid structure. The mesh-like gyroid structure does not compromise structural integrity. Therefore, weight of the implant may be reduced. Furthermore, the manufacturing material cost is reduced. The design of the implant may aim to provide a balance between mechanical reinforcement and biological compatibility, key factors in long-term implant success.

[0065] An example clinical scenario may include a patient presenting with a growth on the sternum, requiring resection and reconstruction of the sternum bone. A surgeon may, during a surgical procedure, open-up the patient and determine how much bone and tissue to resect. In the case where multiple implants are manufactured of varying combinations of parameters, the surgeon may select the implant of the optimal size for the patient. Due to the varying number of openings, the surgeon may select the optimally sized implant based on the resection amount, and then select the optimal attachment points of the implant for the specific anatomy of the patient.

[0066] In some examples, scans of the patient may be obtained before surgery. Based on the scan and patient consultation, a customized set of parameters may be determined for the patient. The implant may be manufactured, prepared (such as polishing and / or sandblasting) and sterilised. Thereafter, the implant may be implanted during surgery.

[0067] The design may mimic a normal anatomy and shape of the average human sternum, creating a cosmetically pleasing structural support for the anterior chest wall. It may have a relatively low- profile without compromising structural strength, allowing superficial tissue, pectoral muscles and skin to easily close over the implant. The posterior curvature shape may recreate a normal contour of the chest wall to replace the native sternum removed during surgery.

[0068] The foregoing description has been presented for the purpose of illustration; it is not intended to be exhaustive or to limit the technology to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above disclosure.

[0069] The language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the present disclosure be limited not by this detailed description, but rather by any claims that issue on an application based hereon. Accordingly, the present disclosure is intended to be illustrative, but not limiting, of the scope of any accompanying claims.

[0070] Finally, throughout the specification and any accompanying claims, unless the context requires otherwise, the word ‘comprise’ or variations such as ‘comprises’ or ‘comprising’ will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

CLAIMS:

1. A sternal implant (100) for implant into a body, comprising: an outer frame (102) forming a structurally rigid portion and including a plurality of openings (104) configured to accommodate sutures for affixing the outer frame (102) to the body; a central structure connected within the outer frame (102) and including: a filling portion (108) in the form of a layer having a construction including multiple channels (109) configured to allow for fluid drainage and tissue ingrowth of tissue generated by the body.

2. The sternal implant (100) of claim 1 , wherein the central structure includes: at least one reinforcing rib (106) spanning between opposing sides (122, 123) of the outer frame (102).

3. The sternal implant (100) of claim 1 or 2, wherein the outer frame (102) includes a longitudinal posterior curvature (158) offset (160) from a zero plane (163).

4. The sternal implant (100) of claim 1 or 2, wherein the outer frame (102) includes a transverse posterior curvature (152) offset from a zero plane (163).

5. The sternal implant (100) of claim 3 or 4, wherein the posterior curvature (158,152) is offset from a zero plane (163) between 0mm to 20mm to conform to an anatomy of the body.

6. The sternal implant (100) of any one of the preceding claims, wherein the outer frame (102) is elongated having opposing longitudinal sides (122,123) and the central structure includes at least two reinforcing ribs (106) spanning between the longitudinal sides (122,123).

7. The sternal implant (100) of claim 6, wherein the central structure includes four reinforcing ribs (106) spanning between the longitudinal sides (122,123).

8. The sternal implant (100) of any one of the preceding claims, wherein the central structure has a height offset between an outer dimension of the outer frame (102) with the central structure being of reduced height compared to the outer frame (102).

9. The sternal implant (100) of any one of the preceding claims, wherein the filling portion (108) is an additive manufactured filling pattern.

10. The sternal implant (100) of any one of the preceding claims, wherein the filling portion (108) is an additive manufactured gyroid filling pattern.

11. The sternal implant (100) of any of the preceding claims, wherein the filling portion (108) has multiple sections of different filling pattern orientations.

12. The sternal implant (100) of any one of the preceding claims, wherein the outer frame (102) includes a flattened portion at one or both of a superior end (124) and an inferior end (120).

13. The sternal implant (100) of claim 12, wherein the superior end (124) is configured to be positioned proximate a manubrium of the body, and wherein the inferior end (120) is configured to be positioned proximate a xiphisternum of the body.

14. The sternal implant (100) of any one of the preceding claims, wherein the outer frame (102) is unpolished to improve osteointegration and the plurality of openings (104) are polished to reduce abrasion of sutures.

15. The sternal implant (100) of any one of the preceding claims, wherein the plurality of openings (104) are chamfered suture holes.

16. The sternal implant (100) of any one of the preceding claims, wherein the openings of the plurality of openings (104) are spaced equidistant from each other.

17. The sternal implant (100) of any one of the preceding claims, wherein a cross-section view of the outer frame (102) is an octagonal shape.

18. The sternal implant (100) of any one of the preceding claims, wherein a top view of the outer frame (102) is an octagonal shape.

19. The sternal implant (100) of any one of the preceding claims, wherein the implant (100) is formed by additive manufacturing of a titanium-aluminium-vanadium alloy.

20. The sternal implant (100) of any one of the preceding claims, wherein the outer frame (102) is chamfered or filleted near an inner face (168) and an outer face of the outer frame (102), providing a curved portion of the outer frame (102) for tissue growth around the outer frame (102).

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