Optimized guide kit for cutting a jaw bone

Abstract

A cutting guide kit for a jawbone comprising a first and second anchor that can be releasably secured to the jawbone to delimit a portion of pathological jawbone, with the first and second anchors respectively having a first and second cutting plane, and with the first and second anchors being rigidly connected to each other via a crosspiece on which reference elements are disposed; a support for a bone graft that replaces the pathological portion of the jawbone, including projections that can be positionally referenced with respect to the reference elements to identify a desired installation position of the support with the bone graft attached; and the support having a window so that, when the projections are positionally referenced with respect to the reference elements identifying a desired installation position of the bone graft, the window is positioned at a vertical level higher than that of the anchors, so as to allow the passage of a fastening element to secure the bone graft to the jawbone.

Description

[0001] "OPTIMIZED GUIDE KIT FOR CUTTING A JAW BONE"

[0002] DESCRIPTION

[0003] TECHNICAL FIELD

[0004] The present invention relates to the field of surgery and, more speci fically, to equipment and devices for mandibular surgery that involve replacing a pathological bone portion of the j awbone with a graft , preferably sourced from the patient ' s fibula or cal f bone .

[0005] STATE OF THE ART

[0006] In the fields of maxillofacial surgery, otorhinolaryngology (ENT ) , and plastic surgery, cutting guides are widely used to facilitate the removal of a pathological bone portion of the j awbone , e . g . , a portion af fected by a tumor . Speci fically, two resections are required to isolate the pathological bone portion of the j awbone .

[0007] To achieve this , currently available commercial cutting guides include anchors that can be releasably secured to the j awbone , e . g . , via screws . These guides feature two cutting planes that serve as supports for the blade of the resection instrument , guiding the surgeon during the osteotomy when the anchors are in place . The most advanced cutting guide solutions have anchors rigidly connected to each other, ensuring that the precise spatial relationship between the two healthy bone portions is maintained even after the removal of the pathological bone portion .

[0008] Furthermore , once the pathological bone portion has been resected, current solutions involve positioning a guide with the healthy bone graft onboard in a predefined position relative to the anchors to identi fy the correct attachment position of the healthy bone graft to the mandibular portions . However, even the most advanced commercially available solutions have numerous disadvantages . Speci fically, it is not possible to apply fixation plates to secure the healthy bone graft to the mandibular portions while the anchors and, in particular, the support for the healthy bone graft are in place . Consequently, it is first necessary to apply temporary fixation elements to hold the bone graft in the desired position, allowing the anchors and support to be removed .

[0009] As can be understood, these solutions are complex and invasive for the patient , e . g . , additional holes must be drilled to apply the temporary fixation elements , extending operative times and potentially causing movements of the bone graft when the temporary fixation elements are removed to apply the definitive fixation plates .

[0010] There is therefore a persistent need for simpler solutions from a structural perspective that minimi ze the surgical phases of osteotomy to reduce the invasiveness of the operation on the patient , decrease operative times and the number of components used, while simultaneously increasing the precision in positioning the bone graft as a replacement for a pathological bone portion .

[0011] OBJECT AND SUMMARY OF THE INVENTION

[0012] The present invention aims to at least partially address the above- mentioned needs , achieving this goal through a j awbone cutting guide kit for a patient as described in claim 1 .

[0013] According to a preferred embodiment of the present invention, a cutting guide kit is provided comprising components with an optimi zed structural configuration that enables a surgeon to install a replacement bone graft for a resected pathological mandibular portion while the cutting guide kit is applied to the awbone . Speci fically, according to the invention, it is possible to apply a fixation element , e . g . , an osteosynthesis plate , while the cutting guide kit is in place and to easily remove the cutting guide kit after the fixation element has been applied. This approach enhances the precision of osteotomy procedures, reduces operative times, and decreases the invasiveness of the intervention for the patient. In particular, to achieve this result, the cutting guide kit includes a first and a second anchor that can be releasably secured to the patient's jawbone, e.g., via screws, to delineate a pathological portion of the awbone to be removed. Additionally, these first and second anchors feature, respectively, a first and a second cutting plane. These cutting planes guide the surgeon's cutting tool for resecting the pathological bone portion to be removed from the j awbone .

[0014] To maintain the relative position of the healthy mandibular portions disconnected at the conclusion of the osteotomy, the first and second anchors are rigidly connected by a crossbar, such that once one of the anchors is secured to the jawbone, the exact position for securing the other anchor on the jawbone is immediately determined. The crossbar, preferably manufactured as a single piece with the anchors, includes reference elements.

[0015] To attach a healthy bone graft to the jawbone after the pathological bone portion has been removed, the cutting guide kit includes a support for the replacement bone graft for the resected portion of the jawbone. This support is dimensioned and shaped to match the geometry of the removed pathological bone portion. Specifically, this support is used to position a healthy bone graft harvested from another part of the patient's body, e.g., the fibula or calf bone, in the correct installation position according to clinical osteosynthesis practices.

[0016] Since the support is sized to fit precisely into the area of the jawbone from which the pathological bone portion was removed, minimizing the distance between the bone graft and the healthy mandibular portions, it is necessary to determine the correct installation position by adjusting the support's placement along its insertion direction into the space left by the removed pathological bone portion . To identi fy the desired installation position for the bone graft carried by the support , the support includes proj ections that can be spatially aligned with the reference elements of the anchors .

[0017] In this way, once these proj ections are aligned with the reference elements— e . g . , the proj ections may be positioned over the reference elements so that their respective edges are superimposed— the desired installation position for the bone graft in the j awbone can be identi fied .

[0018] According to the invention, the support is designed such that the healthy bone graft can be secured to the j awbone while the support is in place , eliminating the need for temporary fixation plates to hold the bone graft in position after the cutting guide kit is removed from the j awbone to free the surgical field for installing the definitive fixation plates .

[0019] Speci fically, to achieve this , the support features a window elongated in the direction of the crossbar and preferably open at the support ' s ends , dividing it into an upper and a lower portion . Through this window, access can be gained to a portion of the healthy bone graft to be installed . Based on this structural configuration, when the anchors are secured to the j awbone and the support is positioned so that the proj ections align with the reference elements , thereby identi fying the desired installation position of the bone graft , the window is located vertically above the anchors to allow passage of a fixation element to secure the bone graft to the j awbone .

[0020] Thus , through the window, a fixation element , e . g . , an osteosynthesis plate , can be inserted to extend from one healthy mandibular portion to the other, longitudinally opposed relative to the support , passing through the window and remaining in contact with and preferably adj acent to the healthy bone graft portion to be installed in the j awbone . This configuration allows the support to be removed after the healthy bone graft has been secured to the j awbone , without interfering with the fixation element during removal .

[0021] DESCRIPTION OF THE DRAWINGS

[0022] The structural and functional features of the mandibular cutting guide kit can be better understood from the detailed description below, which re fers to the accompanying figures that depict a preferred, non-limiting embodiment of the invention, in which :

[0023] • Fig . 1 shows a perspective view of the cutting guide kit in operation according to a first preferred embodiment of the present invention;

[0024] • Fig . 2 shows a detailed perspective view of the configuration of the anchors secured to a patient ' s j awbone ;

[0025] • Fig . 2a shows a detailed perspective view of the configuration of the anchors secured to a patient ' s j awbone according to another preferred embodiment of the present invention;

[0026] • Fig . 3 shows a detailed perspective view of the configuration of the anchors in Fig . 2 , with the removable overhanging ends removed;

[0027] • Figs . 4 and 5 respectively show a perspective view of the cutting guide kit from Fig . 1 , including a fixation element passing through a window in the support for the healthy bone graft , and a perspective view of the patient ' s j awbone after the removal of the cutting guide kit ;

[0028] • Fig . 5a shows a view of the cutting guide kit from Fig . 1 , illustrating in greater detail the recess configuration on the support for the bone graft ;

[0029] • Fig . 6 shows a perspective view of the cutting guide kit in operation according to a preferred variant embodiment of the present invention; • Fig. 7 shows a perspective view of the cutting guide kit in operation according to another preferred variant embodiment of the present invention;

[0030] • Fig. 8 shows a detailed view of a portion of the fibula or calf bone, to which the cutting guide kit's support is attached for harvesting a healthy bone graft;

[0031] • Figs. 9 and 10 respectively show a view of the cutting guide kit's support from Fig. 6 fixed to a portion of the patient's fibula or calf bone, and a view of the cutting guide kit's support from Fig. 6, with the healthy bone grafts harvested from the fibula or calf bone portion.

[0032] DETAILED DESCRIPTION OF THE INVENTION

[0033] In a preferred embodiment of the present invention, as illustrated in Fig. 1, the mandibular cutting guide kit, referred to as G, is used in osteotomy surgeries to replace a pathological bone segment of the jawbone (M) with a healthy bone graft. This graft is preferably harvested from a section of the fibula or calf bone of the patient. As shown in more detail in Fig. 2, the cutting guide kit includes a first anchor (1) and a second anchor (2) , each releasably attachable to a healthy portion of the awbone. When in operation, these anchors are positioned longitudinally apart, delineating the pathological portion of the jawbone (Ml) , such as a segment affected by a tumor, from the healthy areas.

[0034] Specifically, the first and second anchors are shaped to extend laterally along the anatomical profile of the jawbone bone, allowing them to fit snugly. The anchors feature holes (3) for securing them to the patient's jawbone, such as with screws. Their anatomical shape ensures accurate placement and orientation on the bone for reliable and efficient attachment. The first and second anchors also include first (la) and second (2a) ends, positioned adjacent to the bone segment to be resected. These ends are shaped to form cutting planes (Pl, P2) , providing surfaces for guiding the blade of the resection tool. This ensures precision during osteotomy when the anchors are in place. To enhance blade guidance, portions of the first and second ends may extend vertically as overhanging sections, increasing the surface area available for blade alignment. This design minimizes errors during the resection of the pathological bone segment. If the overhanging sections are significantly extended and prone to lateral flexing under the blade's pressure, support elements (lb, 2b) can be added. These connect each anchor to the respective overhanging end, providing structural reinforcement and preserving the correct inclination of the cutting planes (Pl, P2) . The anchors are typically fixed at the base of the jawbone to keep the surgical field as unobstructed as possible, with the overhanging ends extending toward the patient's teeth to define the pathological segment (Ml) for removal. Once cuts parallel to the first and second cutting planes (Pl, P2) are completed, the pathological segment (Ml) can be excised and replaced with a healthy bone segment (M2) , preferably harvested from the patient's fibula or calf bone. To prevent movement between the disconnected healthy portions of the awbone following the removal of the pathological segment, the first and second anchors are rigidly connected by a crossbar (4) . This crossbar is designed to extend between the two anchors, protruding from the jawbone (M) with curved ends and a straight central section. The crossbar (4) typically has a uniform cross-sectional shape, preferably square, ensuring rigidity to minimize elastic deformation when the anchors are secured to the jawbone. This design allows for precise positioning of the second anchor once the first is placed, eliminating the need for manual adjustments by the surgeon. The crossbar helps maintain the relative positions of the healthy bone portions before and after the removal of the pathological segment (Ml) , ensuring structural integrity and alignment during the procedure. Additionally, the overhanging sections of the anchor ends (la, 2a) , when present, are designed to be removable after the pathological segment (Ml ) has been resected . Support elements ( lb, 2b ) , i f used, can also be removed alongside these sections to further clear the surgical field . For example , the connection zone between the overhanging portion and the main anchor body can have a reduced thickness , enabling easy breakage or detachment of the overhanging sections . This facilitates access to the space between the anchors and the teeth for subsequent surgical steps . The removal of the overhanging sections creates additional room for inserting the healthy bone graft (M2 ) into the j awbone using the bone graft support ( 5 ) included in the cutting guide kit ( G) . This support is employed to correctly position the healthy bone segment within the j awbone , replacing the resected pathological segment (Ml ) . In particular, the support has a shape designed to be inserted between the healthy portions of the j awbone to position the healthy bone graft in the correct position as required by osteosynthesis clinical practice . According to a further aspect of the invention, the support 5 features a window 6 extending along the length of the support , preferably from one end to the oppos ite longitudinal end, dividing the support into two portions , an upper portion 5a and a lower portion 5b . The upper and lower portions are rigidly connected by a pair of arcuate connecting elements 7 , arranged opposite a recess 8 on the support 5 , parallel to the window 6 and designed to hold the healthy bone graft in use . These arcuate connecting elements extend transversely, and preferably perpendicularly, above the window 6 , positioned oppos ite the recess 8 . Therefore , when the support 5 is placed between the two healthy portions of the j awbone , the recess 8 with the surrounding healthy bone portion faces the oral cavity of the patient . Moreover, the longitudinal ends of the support 5 and the healthy bone portion have an inclination that is substantially parallel to the cutting planes Pl and P2 , ensuring the smooth insertion of the support 5 into the space left by the removed pathological bone segment Ml . Furthermore , the support 5 is used to harvest the bone graft from a healthy bone portion of the patient , e . g . , from the fibula or cal f bone . When this support is positioned on a healthy bone portion to be harvested, the recess 8 is preferably shaped to follow the profile of the bone portion closely, thereby defining a seat for the bone graft once resected . Preferably, the longitudinal ends of the support 5 are flanged and inclined in a way that is substantially parallel to the f irst and second cutting planes Pl and P2 arranged on the anchors . In this manner, the construction of the ends of the support 5 is designed to define additional planes for supporting the surgeon' s blade to perform the resection of the healthy bone graft , ensuring that the walls of the bone graft have an inclination matching that of the walls of the healthy j awbone portions between which the graft is inserted . Thus , when the cutting guide kit G is in use with the healthy bone graft M2 placed on the support 5, the surfaces of the longitudinal ends of this support are in contact with the respective surfaces of the first and second ends la and 2a of the anchors , i . e . , they contact the first and second cutting planes Pl and P2 . In other embodiments not shown in the figures , the ends la and 2a of the anchors are removable to completely remove the cutting planes Pl and P2 from the anchors . In this case , the support 5 is maintained in place by the crossbar 4 , and the corresponding resected portions of the bone graft are in the correct position, directly contacting the healthy cut portions of the awbone without the flanges contacting the anchors 1 and 2 . Moreover, the flanged configuration of the longitudinal ends of the support 5 increases the surface area of contact between the healthy j awbone portions and the ends of the support , thus improving the stability of the support ' s position when in use . Preferably, to lock the support 5 in the desired position between the healthy j awbone portions , the flanged ends of the support may be elastically deformable and inclined at a lesser angle than that of the j awbone ' s walls , so that when the support is in use , the flanged ends are bent and in contact with the healthy j awbone walls , exerting an elastic reactive force against these walls . It should also be noted that the geometry and dimensions of the support and the healthy bone portion are adapted according to the si ze and geometry of the removed pathological bone portion to minimi ze the gaps between the bone portions of the j awbone and the healthy bone portion being installed . Thus , when the support 5 is positioned in the space left by the removed pathological bone portion, any lateral movements toward the healthy awbone portions are minimi zed, and the healthy bone graft is substantially in contact with the healthy j awbone portions , aiding bone healing . Therefore , to correctly position the healthy bone portion, the position of the support 5 must be adj usted in the direction of insertion within the void left by the removed pathological bone segment Ml . Speci fically, to achieve this , the crossbar 4 includes reference elements 9 , preferably two , located along the central straight section of the crossbar, preferably cubic in shape , with dimensions matching the section of the crossbar 4 . The support also includes proj ecting elements 10 , preferably two, extending as cantilevers and shaped such that each end, when the anchors and support are in use , is positioned relative to the reference elements 9 to identi fy the correct position of the support 5 in the direction of insertion within the void between the healthy j awbone portions . Speci fically, it is possible to identi fy an axial distance from the reference element ' s end edge to position each end of the proj ecting elements 10 , thereby identi fying the correct position of the support 5 and, consequently, the healthy bone portion to be installed . Preferably, the ends of the proj ecting elements 10 have a face directed toward the reference elements 9 with the same dimensions as the face of the reference elements directed toward each proj ecting element ' s end, so that when the edges of these faces overlap, the desired position of the support is identi fied .

[0035] Preferably, the various components of the cutting guide kit G described above are made of a biocompatible and sterili zable plastic material , more preferably of photoreactive methacrylic resins for applications compatible with additive manufacturing . According to a preferred embodiment shown in Fig . 6 , in the case of prostheses with two healthy bone portions , the first and second anchors 1 , 2 are always used, rigidly connected by the crossbar 4 , which is longer and angled to follow the more extensive resection area . Similarly, the support 5 is also longer and angled, preferably with both the anchors and the support having a greater number of reference elements 9 and proj ecting elements 10 , preferably three , to identi fy the correct installation position of the bone graft . For example , the upper and lower portions 5a, 5b o f the support may be made in two separate pieces and rigidly connected at the desired angular orientation by a closing element 13 . For example , in Fig . 9 , the support 5 is shown in place on a healthy bone portion to harvest a first and second bone graft M2a, M2b . This support features a first and second body 5a, 5b, longitudinally spaced and connected by a longitudinal connecting element 5c . Each body of the support has the same construction as described above , i . e . , an upper and a lower cylindrical element , separated by the window 6 , preferably open at the ends to allow the passage o f the fastening element 12 when the support is in use in the patient ' s mouth . To harvest the bone grafts , this support 5 is placed on the fibula, fixing the first and second bodies 5a, 5b to the fibula using screws inserted into the respective holes 11 . The support is thus used to guide the resection of the necessary bone portions . Once the bone grafts are harvested on each body, the support 5 is removed from the fibula, and the longitudinal connecting element 5c is cut to separate the first and second bodies from each other . Speci fically, the first and second bodies have longitudinal ends with inclined surfaces such that when positioned in the patient ' s mouth according to the desired orientation, the bodies are oriented with these surfaces in contact , and locked together by the closing element 13 ( Fig . 6 ) . In this way, when the support 5 is assembled and positioned in a desired position in the patient ' s mouth, the surgeon can pass the fastening element 12 through the window to secure the bone grafts to the healthy awbone portions . According to another preferred embodiment shown in Fig . 7 , in the case of prostheses with two or more healthy bone portions , the support 5 may include multiple windows 15 instead of the window 6 , preferably located at the longitudinal ends of the guide and in the interface area between the healthy grafts , through which it is possible to access the healthy bone portions to be fixed to the j awbone M . Speci fically, a reduced-length fastening element 16 , preferably adapted to the patient ' s awbone shape and included in the cutting guide kit G provided to the surgeon, can be applied inside each window 15 to secure the healthy bone graft portion to the j awbone or another healthy graft portion . According to another preferred embodiment of the present invention not shown in the figure , the connecting elements 7 are removable , allowing the separation of the upper portion 50a from the lower portion 50b of the support 5 . This construction feature facilitates the surgeon during the surgical phase . Speci fically, by keeping the healthy bone graft fixed to the lower portion 50b of the support 5 , the upper portion 50a can be removed, for example , before inserting the support into the patient ' s mouth, so that when the support is in use with the proj ecting elements 10 positioned relative to the reference elements 9 , the upper portion is separated from the lower portion, giving more freedom in the surgical field . This further facilitates the assembly of the fastening element 12 . According to yet another preferred embodiment of the present invention (not shown in the figure ) , the arcuate connecting elements 7 can be breakable or reseable , allowing the removal of the upper portion 5a of the support 5 in use , thus exposing the upper part of the surgical field . The fastening function is still carried out by the remaining elements , namely the anchors 1 , 2 , and the unremoved portions of the support 5 , e . g . , the lower portion 5b, which remain fixed together and with the bone segments . The anchors 1 , 2 , and the lower portion 5b of the support 5 are shaped to define a longitudinal edge that follows the profile of the longitudinal ends of the fastening element 12 . Speci fically, this longitudinal edge extends transversely to define a contact surface for each respective longitudinal end of the fastening element 12. In this way, when the cutting guide kit is in use, and the fastening element 12 is positioned at a vertical level higher than the contact surface defined by the anchors 1, 2, and the lower portion 5b of the support 5, this contact surface is used so that each longitudinal end of the fastening element rests on it, defining the vertical position for its installation. Advantageously, this construction feature reduces the surgeon's effort to maintain the fastening element 12 in the desired vertical position by hand, e.g., using a tool, while also increasing the precision of mounting the fastening element 12 to the j awbone .

Claims

CLAIMS1. Cutting guide kit (G) for a jawbone (M) comprising:• A first and a second anchor (1, 2) releasably attachable to the awbone (M) to delimit a pathological portion of the jawbone (Ml) , with the first and second anchor each having a first and a second cutting plane (Pl, P2) , and the first and second anchors being rigidly connected to each other via a vertical crossbar (4) on which reference elements (9) are arranged;• A support (5) for a bone graft (M2) replacing the pathological portion of the jawbone (Ml) , and comprising projecting elements (10) positionally referenced relative to the reference elements (9) to identify a desired installation position of the support with the bone graft on the jawbone (M) ; and said support having a window (6) such that, when the projecting elements (10) are positionally referenced relative to the reference elements (9) to identify the desired installation position of the bone graft, the window (6) is at a different level from that of the anchors (1, 2) so as to allow the passage of a fastening element (12) to secure the bone graft to the jawbone.

2. Cutting guide kit (G) according to claim 1, wherein the fastening element (12) is provided pre-shaped in the kit based on the patient's jawbone configuration.

3. Cutting guide kit (G) according to claim 1 or 2, wherein the window (6) is open at the ends, dividing the support into an upper portion (50a) and a lower portion (50b) .

4. Cutting guide kit (G) according to claim 3, wherein the support (5) includes arcuate connecting elements (7) that extend transversely over the window (6) to rigidly connect the upper and lower portions (50a, 50b) .

5. Cutting guide kit (G) according to claim 4, wherein the arcuate connecting elements (7) are at least partially removable so that when the support (5) is in use, the upper portion (50a) is disconnected from the lower portion (50b) of the support with the projecting elements (10) positionally referenced relative to the reference elements (9) .

6. Cutting guide kit (G) according to any of the preceding claims, wherein the bone graft support (5) includes a first and second body (5a, 5b) , each having a housing recess for a respective first and second bone graft (M2a, M2b) , and the first and second bodies are longitudinally connected by a removable longitudinal connecting element (5c) to separate the first and second bodies, with the first and second bodies having first and second longitudinal ends defining inclined surfaces such that when the inclined surfaces of the first and second longitudinal ends face and are in contact, the first and second bodies (5a, 5b) are angularly referenced.

7. Cutting guide kit (G) according to any of the preceding claims, wherein the first and second anchors (1, 2) have a first and a second end (la, 2a) that extend at least partially cantilevered in use towards the patient's teeth, on which the first and second cutting planes (Pl, P2) are arranged, with these first and second ends also extending in use at a vertical level higher than that of the window (6) , and are at least partially removable so that when removed from the respective anchors and the cutting guide kit is in use, they free the passage for the fastening element (12) through the window (6) .

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