Methods for bone regeneration and surgical planning

Abstract

A method for bone regeneration and surgical planning comprising the following steps: Providing a digital dataset of a 3D image of the bones using digital X-ray, orthopantomography (OPT), computed tomography (CT), digital volume tomography (DVT) and / or magnetic resonance imaging (MRI); Identification of deviations from normal anatomy using 3D imaging; Creation of a real 3D model that corresponds to the 3D scan; Identifying deviations based on the real 3D model for planning a surgical intervention, whereby The real 3D model accurately reproduces the anatomy of the bones, including deviations within a tolerance range of ±0.05 mm. During the planning phase, the arrangement of bones and bone fragments is examined, as well as the accessibility of the bone fragments and whose removability is determined, Free-floating bone fragments that have no connection to the other bones are identified in the 3D scan before the actual 3D model is created, and In the 3D scan, appropriate spacers are incorporated between the free-floating bone fragments and the remaining bones. to hold the free-floating bone fragments.

Description

[0001] The present invention relates to a method for replicating bones or soft tissue and for planning a surgical procedure. In particular, the invention relates to a simulation of a procedure on a replicated skull. Deviations from normal anatomy can be detected in this process.

[0002] Anatomy encompasses the shape, position, and structure of body parts, organs, tissues, cells, and the skeleton. Since, for example, the shape, position, and size of bones allow only relatively minor tolerances, a healthy person can be considered to have a standard anatomy. However, deviations from this standard anatomy can occur. A distinction must first be made between congenital and acquired anatomical changes. Acquired anatomical changes can be caused by disease or injury, for example. In any case, corrective surgery may be advisable; in the case of accident-related anatomical changes, the procedure is particularly urgent.

[0003] Especially in cases of severe head injury, it is advisable to assess the current condition before surgery in order to prepare an appropriate surgical strategy. Various imaging techniques are available for this purpose, such as digital X-rays, computed tomography (CT), magnetic resonance imaging (MRI), digital volume tomography (DVT), etc.

[0004] Even if the operating surgeon has been able to obtain a preliminary picture of the current condition using such imaging techniques, they still face significant difficulties in performing the operation as planned in the case of a severe injury, such as a skull base fracture. This is partly because large amounts of blood can leak out during the actual operation, making it difficult to visualize the fractured skull fragments. Furthermore, the images displayed on a computer screen only provide an unsatisfactory representation of the actual state of the injuries, as the displayed 2D image can lead to misinterpretations of the relative sizes of individual components. It is also important to remember that the operating surgeon is not a theorist. Their work and specialization lie in the practical, hands-on execution of operations.Therefore, he often finds visualization using computer displays unsatisfactory. II. Technical Background

[0005] It is therefore known from the state of the art to produce anatomical models in human and veterinary medicine, on the basis of which a surgeon can plan an operating strategy.

[0006] German patent DE 102007042922A1 discloses, for example, a method for producing anatomical models in human and veterinary medicine, in which the model is manufactured using rapid prototyping technology. Rapid prototyping technology includes, for example, 3D printing or stereolithography for generating a tangible 3D anatomical model. For acquiring patient data, 2D or 3D ultrasound using an ultrasound device is proposed, as CT scans would expose the patient to excessive radiation and MRI scans are too expensive. Using the ultrasound device, organs such as the liver or heart can be imaged in three dimensions to identify disease patterns. The ultrasound image data is imported into image processing software, and the relevant anatomical structures, i.e., the organs of interest, are segmented.Based on the data, a real-world model is created that the doctor can use to support diagnosis and also to plan an operating strategy using the model.

[0007] A disadvantage of the proposed method is its poor applicability to bone reconstruction or the identification of deviations from normal anatomy. In the case of bone fractures, such as a skull fracture, the proposed method could only provide a relatively inaccurate picture of the actual condition.

[0008] Further documented prior art in this technical field can be found in the following documents: US 2012 / 0 224 755 A1, Source Graphics, 1530 N. Harmony Circle, Anaheim, CA 92807: Datasheet ProJet® 3500 DP & MP, prepared on January 26, 2013; US 2011 / 0 319 745 A1; US ​​2012 / 035 888 A1; DAHLEN, C.; ZWIPP, H. Computer-assisted surgical planning. Der Unfallchirurg, 2001, Vol. 104, No. 6, pp. 465-465; KHALYFA, Alaadien, et al. Development of a new calcium phosphate powder-binder system for the 3D printing of patient-specific implants. Journal of Materials Science: Materials in Medicine, 2007, Volume 18, No. 5, pp. 909-916, US 2012 / 0285002 A1. III. Description of the invention a) Technical problem

[0009] The invention therefore proposes a method for replicating bones and planning a surgical procedure, in which the required accuracy of the replicated bones can be achieved and a substantiated surgical strategy can thereby be planned. b) Solution of the task

[0010] The invention takes advantage of the fact that the latest versions of 3D printers can achieve an unprecedented resolution. For example, the Projet 3510 MP 3D printer, manufactured by 3D Systems, can be used within the scope of the present invention.

[0011] The proposed 3D printers achieve a resolution of 0.025–0.05 mm. To achieve a correspondingly accurate reproduction in the printed 3D models, the invention further proposes providing a digital dataset of a 3D scan of the bones using digital X-ray imaging, including orthopantomography (OPT), computed tomography (CT), digital volume tomography (DVT), and / or magnetic resonance imaging (MRI). These methods provide the correspondingly high resolution for the digital 3D scans.

[0012] As a result, according to the invention, a real 3D model of the patient's actual condition, i.e., the anatomy of the bones including deviations from the regular anatomy, is produced, which lies within a tolerance range of ± 0.05 mm, preferably ± 0.025 mm, compared to the patient's actual bones.

[0013] Furthermore, according to the invention, it is proposed that the real 3D model be used in planning the surgical strategy. The arrangement of the bones and the arrangement of bone fragments are examined. In addition, the accessibility of the bone fragments and their removal are determined using the real 3D model.

[0014] Due to the high imaging accuracy of the bones achieved by the real 3D model according to the invention, and the associated very high reliability of the 3D model, more advanced surgical strategies can be planned using the 3D model than was possible with the prior art. With the 3D model according to the invention, which can be, for example, a skull or a partial skull, even the smallest fragments, such as 2 mm or less than 1 mm, can be precisely identified with regard to their size and arrangement. This allows the operating surgeon to immediately determine the best course of action for each fragment. One challenge lies in determining the best way to access the individual bones, bone parts, or bone fragments, and another in determining how the individual bones or bone fragments should be treated during the operation.

[0015] Preferably, when bone fragments are identified, it is first assessed whether they can be reused. This means determining whether the bone fragments can be reinserted into the broken bone to restore normal anatomy. If it is decided that the bone fragments cannot be reused, it is also preferably assessed how best to remove them. In particular, it is important to determine the orientation in which the bone fragments can be removed most easily and with the lowest risk of additional injury.

[0016] It is further proposed that, in cases where bone fragments are not reusable, corresponding bone replacement parts are digitally designed based on the 3D scan and subsequently manufactured as physical parts from a suitable material. Thus, the advantage of the surgical planning according to the invention is that not only can deviations from normal anatomy be correctly identified using the 3D model, but all preparations for the operation can also be completed in advance, so that during the operation the bone can be reassembled in such a way that it corresponds to normal anatomy. Therefore, the method according to the invention serves to prepare for only a single surgical procedure.

[0017] Advantageously, the design of a bone graft is achieved by assembling the bone fragments, if multiple bone fragments need to be replaced, to determine the shape of the graft. This can be done using a real 3D model, particularly by the operating surgeon. This practical approach allows the surgeon to visualize the actual required bone graft. Often, this provides the surgeon with additional information that would not be apparent from the digital design, which is primarily carried out by a technician. However, the design of bone grafts should primarily be based on the digital 3D scan.Starting with the 3D scan as a digital model, the bone fragments to be replaced can be identified and assembled on the computer to obtain a digital 3D model of the desired bone replacement. This 3D model of the bone replacement then preferably serves as the basis for manufacturing the physical bone replacement. The operating surgeon's observations, gained during the review of the real 3D model and the assembly of the bone fragments, can also be incorporated into the data set.

[0018] It is further proposed that, starting with the 3D scan as a digital as-is model, the bone fragments to be replaced are identified and replaced by one or more bone substitutes. The bone substitutes can then be inserted into the designated positions in the remaining bone to obtain a digital 3D target model. This 3D target model then largely corresponds to normal anatomy.

[0019] To obtain the digital 3D target model, the bone fragments to be reused can also be moved to their designated positions. However, even with this theoretically complete digital 3D target model, it's possible that the bone is still incomplete due to gaps, holes, or similar defects. Therefore, a final check is preferably performed, during which the bone replacement pieces can be adjusted as needed.

[0020] The digital 3D target model, now finally completed, can also be produced as a real 3D model, for example by means of 3D printing, if desired by the surgeon.

[0021] It can happen that individual bone fragments or bone pieces are "free-floating" within the patient's body, meaning that they are, for example, completely embedded in the flesh or brain and thus have no connection to the other bones. According to the invention, such free-floating bone fragments or bone pieces are identified in the 3D scan before the actual 3D model is created. According to the invention, corresponding spacers are then incorporated into the digital 3D scan between the free-floating bone fragments or bone pieces and the other bones. The spacers serve to hold the free-floating bone fragments or bone pieces in their actual position within the subsequently created actual 3D model. c) Examples of implementation

[0022] Embodiments according to the invention are described in more detail below by way of example. The figures show: Fig. 1: a first exemplary embodiment of a method according to the invention; Fig. 2: a second embodiment of the method according to the invention.

[0023] In the embodiments from Fig. 1 and Fig. In both cases, it is assumed that a patient with a serious skull injury, such as a skull base fracture, is admitted to a hospital for immediate treatment. In such a case, the urgency of the fastest possible operation is particularly high, meaning that the treatment must be carried out in the shortest possible time with as few steps as possible. This is ensured by the method according to the invention.

[0024] In Fig. In step S100, a digital dataset of a 3D scan of the patient's skull is initially provided. This is done after performing the usual procedures mentioned above, such as computed tomography. Typically, the acquired raw data undergoes segmentation, filtering, etc., as is known from the state of the art, to filter out or better visualize the relevant body parts, in this case, the skeleton or bones.

[0025] The patient is usually placed in an induced coma until the operation to increase their chances of survival.

[0026] Based on the data provided in step S100, two parallel processes now take place: the processing of the digital 3D scan in steps S101 to S103, and the creation of a physical 3D model and its analysis in steps S111 to S114. This approach has the advantage of saving time through the parallel process and allows for two separate, independent analyses of the patient's current condition, i.e., their injuries. This significantly increases the reliability of the analysis and, consequently, the accuracy of the surgical preparations. The chances of a successful operation can therefore also be improved.

[0027] In step S101, the fractures in the skull are identified using a digital 3D scan, i.e., on a computer. The structure of the individual bone fragments is then analyzed. In step 102, it is determined which of the bone fragments can be reused, meaning they can be reinserted into the skull. For those bone fragments that cannot be reused, bone replacement parts are digitally designed. This can be done, for example, by filtering out the bone fragments to be replaced by a bone replacement part and digitally assembling them.

[0028] Based on the computer-generated analyses, a digital 3D target model can now be designed in step S103. In this model, all reusable bone fragments and the designed bone replacement parts were moved to their predicted positions in the skull. This allows for a review of the procedures performed in steps S101 and S102 based solely on the digital data.

[0029] Parallel to the work steps S101 to S103, which deal exclusively with the digital data, a real, physical 3D model is created in step S111, in particular using a 3D printer. This process preferably takes no longer than 8 or 12 hours. However, since this process is still relatively time-consuming, it should be started immediately after the data set is made available in step S100.

[0030] Once the real 3D model of the skull has been completed, the existing fractures can be examined on it by the operating doctors, in particular by the surgeon, in step S112.

[0031] In step S113, the doctors first examine the existing bone fragments. This means they check the shape and size of the bone fragments and their location. Important conclusions can be drawn from this, for example, if a bone fragment has penetrated or injured the brain. In this case, it may be necessary to prepare additional measures for treating the brain before the operation.

[0032] Furthermore, in step S113, the surgeon can also determine the mobility of a particular bone fragment purely through manual means, that is, whether it is wedged, whether it can be rotated, or whether it is accessible from the outside. The primary concern here is whether the bone fragment can be extracted from the outside through an opening using suitable instruments without causing further injury to the skull. Because the assembled skull is physically present in front of the treating surgeon, their experience usually allows them to make an accurate assessment at a glance.

[0033] Furthermore, in step S113, the bone fragments are checked for reusability. For larger fragments, for example, if part of the skull is only fractured, corrective realignment of the bone fragment may be the most sensible solution. However, for smaller, especially splinter-like bone fragments, a bone graft that replaces several smaller, fragmented pieces is usually necessary. Often, the treating physician can determine the need for bone grafts simply by examining the actual 3D model.

[0034] For the design of the necessary bone replacement parts in step S114, it is often useful to remove the bone fragments to be replaced from the 3D model and, where possible, assemble them like a puzzle. Removing the bone fragments from the 3D model using suitable surgical instruments can also serve as training for the subsequent, actual surgery on the patient. In particular, this allows for a review of the size relationships between the bone fragments and the fractured skull, specifically whether the bone fragments can actually be removed from openings in the skull as assumed.

[0035] Once the surgeons have designed the necessary bone replacement parts or reached their conclusions regarding the properties and necessity of bone fragments, they can incorporate this information into the digital 3D target model created in step S103. Since the 3D target model created digitally in step S103 was primarily designed by technicians and / or technically skilled physicians, this step allows for a comparison between the digital design and the design based on the actual 3D model through discussion.

[0036] Based on the findings in step S103 regarding the target 3D model, the necessary bone graft components are then created in step S104. This can be done, for example, by milling or sintering. Zirconium, titanium, plastic, or steel can be used as materials for the bone graft components. An alternative option is to produce the bone graft components using 3D printing. To ensure that the printing material is suitable and, above all, accepted by the body, patient-specific cell cultures could be used. Due to the urgency, the production of the bone graft components should take no more than 12 or 24 hours, ideally less than 8 hours.

[0037] Finally, there is theoretically the possibility that the finished, real bone replacement parts can be tried on the real 3D model and, if necessary, further adjusted.

[0038] Fig. 2 shows one to Fig. 1 alternative embodiment, which, however, includes all steps of the embodiment of Fig. The process is similar to that described in point 1, but follows a different procedure. The key difference is that the creation of the actual 3D model and the fabrication of the bone replacement parts occur in parallel. Since these two steps are the most time-consuming, this approach has the advantage of taking less time overall.

[0039] In step S200, the digital data set of the patient's current condition is provided again.

[0040] Based on this, the fractures are identified in step S201. This step also checks which bone fragments are present and which of them are reusable. Based on these analyses, the following steps are also performed, as in the embodiment of Fig. 1. The necessary bone replacement parts are digitally designed. Likewise, as in the embodiment of Fig. 1. A digital 3D target model was designed.

[0041] Subsequently, the bone replacement parts to be inserted into the patient during the operation are created in step S202. The difference to the embodiment of Fig. The first point is that the bone replacement parts are created solely on the basis of the digital data, without incorporating the findings of the analyses of the real 3D model.

[0042] This is because in the embodiment of Fig. 2. The actual 3D model is not yet complete at the time the bone replacement parts are created in step S202. Based on the data set of the patient's skull's current state provided in step 200, the actual 3D model of the skull is created in step S211, for example, by printing.

[0043] In step S212, the completed 3D model of the skull is modified in the same way as in the embodiment of Fig. 1 (in steps S112, S113, S114) the fractures on the skull were analyzed.

[0044] Once the fabrication of the actual bone replacement parts is completed in step S202, step S213 checks whether the fabricated bone replacement parts fit into the actual 3D model of the skull as intended. This involves a try-in of the fabricated bone replacement parts on the skull model.

[0045] It may turn out that additional adjustments to the manufactured bone replacement parts are necessary in step S214. It is also conceivable that the bone replacement parts were intentionally manufactured slightly too large, particularly at their contact surfaces, so that subsequent adjustments can be made during the fitting on the skull model by grinding, especially of the contact surfaces.

Claims

[1] Method for bone replication and surgical planning, comprising the following steps: Providing a digital dataset of a 3D image of the bones using digital X-ray, orthopantomography (OPT), computed tomography (CT), digital volume tomography (DVT) and / or magnetic resonance imaging (MRI); Identification of deviations from normal anatomy using 3D imaging; Creation of a real 3D model that corresponds to the 3D scan; Identifying deviations based on the real 3D model for planning a surgical intervention, whereby The real 3D model accurately reproduces the anatomy of the bones, including deviations within a tolerance range of ±0.05 mm. During the planning phase, the arrangement of bones and bone fragments is examined, as well as the accessibility of the bone fragments and whose removability is determined, Free-floating bone fragments that have no connection to the other bones are identified in the 3D scan before the actual 3D model is created, and In the 3D scan, appropriate spacers are incorporated between the free-floating bone fragments and the remaining bones. to hold the free-floating bone fragments. [2] Method according to claim 1, wherein the bone fragments are checked for reusability and, in the case of non-reusability, corresponding bone replacement parts are designed and manufactured based on the 3D scan. [3] Method according to claim 2, wherein in the design of a bone replacement part the bone fragments to be replaced are identified and the bone replacement part is created by assembling the bone fragments. [4] Method according to one of the preceding claims 2 or 3, where, starting from the 3D scan as a digital as-is model, the bone fragments to be replaced are filtered out and replaced with bone substitute parts, and The bone replacement parts are inserted into the remaining bone at the designated positions to obtain a digital 3D target model. [5] Method according to claim 4 and one of claims 2 or 3, wherein to obtain the digital 3D target model the recycled bone fragments are also moved to the intended positions. [6] Method according to one of the preceding claims 4 or 5, wherein a final check of the completed digital 3D target model is carried out, in which the bone replacement parts are adapted to the remaining bones and the recycled bone fragments, if necessary. [7] Method according to any of the preceding claims 2-6, wherein the design of the bone replacement parts is initially carried out on the basis of the real 3D model. [8] Method according to any of the preceding claims, wherein the real 3D model is produced by means of 3D printing. [9] Method according to any of the preceding claims, wherein the real 3D model accurately reproduces the anatomy of the bones including deviations within a tolerance range of ±0.025 mm. [10] Method according to one of the preceding claims, wherein the deviations from the regular anatomy are accident-related anatomical changes. [11] Method according to any one of the preceding claims 2 to 10, wherein the bone replacement parts are milled and / or sintered from zirconium, titanium, plastic or steel. [12] Method according to any one of the preceding claims 2 to 11, wherein the bone replacement parts are manufactured by means of 3D printing. [13] Method according to claim 12, wherein patient cell cultures serve as 3D printing material. [14] Method according to any of the preceding claims 2-13, wherein the production of the real 3D model and the bone replacement parts is carried out simultaneously. [15] Method according to any one of the preceding claims 2-14, where the actual 3D model is produced within less than 12 hours, and / or The bone replacement parts are manufactured within less than 12 or 24 hours.

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