Method for determining the parameters of intervertebral implant devices for spinal fusion surgery.

Abstract

1. A method for determining intervertebral implant device parameters, comprising: a) obtaining a three-dimensional image of a patient's spine (10); b) calculating a three-dimensional model of the spine (20); c) acquiring (30) at least one two-dimensional image of the spine; d) performing a first sagittal balance of the three-dimensional model to calculate spinopelvic parameters (50); e) determining (60) intervertebral device parameters corresponding to the intervertebral device to be used; f) applying (70) the intervertebral device parameters to the three-dimensional model of the spine, thus obtaining a corrected three-dimensional model of the spine; g) comparing (80) the corrected three-dimensional model of the spine with the two-dimensional image and performing a second sagittal balance to obtain corrected spinopelvic parameters; h) comparing the corrected parameters to predetermined values ​​to determine if the desired balanced spine has been achieved (90); i) if not, repeating steps e)-h).

Description

[Technical Field]

[0001] The present invention relates to a method for determining intervertebral implant device parameters of an intervertebral implant device for spinal fusion. [Background Art]

[0002] Spinal fusion is a surgical treatment that permanently connects two or more vertebrae of the spine, thereby eliminating movement between the vertebrae to stabilize the patient's vertebral segments.

[0003] Spinal fusion is a treatment in which an intervertebral cage is placed in the patient's spine. The cage serves to maintain the space between the affected vertebrae, allowing bone to grow between them and eventually become part of the spine.

[0004] An intervertebral cage is placed between two adjacent vertebrae after removal of the intervertebral disc that normally occupies this space. A spinal cage can be made of metal, polymer, ceramic, or a combination of different materials.

[0005] The cage has a central cavity, which is filled with a material that promotes bone growth, or with the patient's own bone harvested during the same operation as the fusion, for example from the hip.

[0006] Intervertebral cages aim to improve the stability and balance of the treated spinal segment, while simultaneously relieving pain and restoring function.

[0007] Selection of a cage for intervertebral fusion is generally performed intraoperatively based on simple mechanical trials. These trials allow basic geometric analysis of shape and fit, but do not allow for consideration of many important factors, such as sagittal balance, facet interference, foraminal height, and implant endplate contact.

[0008] Currently, there are no technical tools available to plan the characteristics of cages or other implantable devices used to achieve the desired correction of a damaged spine prior to surgery. [Overview of the project]

[0009] Therefore, in order to achieve the desired correction of spinal defects and thus overcome the problems of the prior art, it is necessary to have the capability to plan spinal surgery by determining the physical and constitutive characteristics of the implanted device.

[0010] These and other objectives are fully achieved by a method for determining intervertebral implant device parameters for an intervertebral implant device for spinal fusion, having the features defined in independent claim 1, and a system for determining intervertebral implant device parameters for an intervertebral implant device for spinal fusion, having the features defined in claim 10.

[0011] Preferred embodiments of the present invention are defined in the dependent claims, and their subject matter is understood to form an integral or integrated part of this specification. [Brief explanation of the drawing]

[0012] Further features and advantages of the present invention will become apparent from the following description, provided merely as non-limiting examples, with reference to the accompanying drawings. [Figure 1] A block diagram of the steps for determining the parameters of an intervertebral implant device for spinal fusion surgery according to the present invention is shown. [Figure 2] This invention presents a system for determining the parameters of an intervertebral implant device for spinal fusion surgery. [Modes for carrying out the invention]

[0013] In short, the method for determining the parameters of an intervertebral implant device for spinal fusion according to the present invention involves a patient-specific analysis of the effects of three-dimensional reconfigured vertebral movement and the interaction between the patient's anatomical structure and the implant device, based on a three-dimensional scan of the patient's spine, such as a CT scan or MRI scan.

[0014] The amount of correction is determined based on an analysis of sagittal balance, taking into account implant devices such as cages of various heights and lordosis / kyphosis angles that are inserted into the intervertebral disc space and affect the geometric relationship between two vertebrae, such as distance, translation, rotation, and angle (lordosis / kyphosis).

[0015] Therefore, by considering various factors such as sagittal balance, intervertebral foramen height / indirect decompression, facet interference due to intervertebral movement, and implant / vertebral endplate contact, the optimal device for implantation can be selected, taking into account the design, length, height, width, and spinal lordosis.

[0016] When performing a CT scan, bone density data for the implant endplate contact site, using Hounsfield values, can also be obtained from the CT scan information.

[0017] Furthermore, the planned information can be used in intraoperative monitoring to check whether the surgical procedure is being performed as planned, or to identify discrepancies between the planned height of the intervertebral foramen and the actual height of the intervertebral foramen.

[0018] Figure 1 shows a block diagram of the steps for determining the parameters of an intervertebral implant device for spinal fusion surgery according to the present invention.

[0019] In the first step 10, a three-dimensional scan image of the patient's spine, such as an MRI or CT image, is obtained.

[0020] In a further step 20, a three-dimensional model of at least one vertebra is created from the scanned image of the spine obtained in step 10 by a method known per se. In one embodiment of the present invention, a complete three-dimensional virtual model of the spine is obtained, in particular as a juxtaposition of a plurality of individual distinct vertebrae. Advantageously, a three-dimensional image of the lower extremity of the spine (sacrum and / or pelvis) is added to the complete model of the spine.

[0021] In a third step 30, at least one two-dimensional X-ray image of the patient's spine, preferably a lateral and / or anteroposterior (sagittal) X-ray image, is acquired. The two-dimensional image comprises a plurality of vertebrae.

[0022] If only limited three-dimensional scan information is available, in a next step 40, matching of the two-dimensional image and the three-dimensional image is performed. Three-dimensional reconstructed vertebra / sacrum / pelvis images are selected from a predefined database of patient-specific three-dimensional vertebrae, the selected images have a predetermined match with the vertebra image in the two-dimensional X-ray image obtained in step 30, and they are then combined to obtain a reconstructed model of the spine that combines the two-dimensional X-ray image and the three-dimensional information at the levels where information is available.

[0023] In step 40, to obtain a three-dimensional virtual reconstructed model of the patient's spine, the three-dimensional images of the reconstructed vertebrae in the database are registered against the two-dimensional images of the vertebrae acquired in the X-ray imaging, for example using a DDR (Digitally Reconstructed Radiograph) algorithm.

[0024] At this point, changes in position between vertebrae and potential interactions between the implant and the patient's anatomy are analyzed.

[0025] In step 50, a first sagittal balance analysis is performed to calculate the patient's spinopelvic parameters, such as pelvic incidence, sacral slope, pelvic tilt, lumbar lordosis, thoracic kyphosis, and sagittal vertical axis, using either the X-ray image or the (complete or reconstructed) three-dimensional model of the spine.

[0026] Advantageously, additional information, such as analysis of intervertebral disc height from previous patients, or analysis of intervertebral disc height relative to healthy levels above and below the index level, is considered to better predict the possible amount of distraction and the resulting implant height and lordosis at the index level.

[0027] Values of spinopelvic parameters are used in a further step 60 to analyze the relationship and motion between different vertebrae in the three-dimensional model of the spine, for example the correction of lordosis or kyphosis that must ultimately be applied to various positions of the spine to obtain a balanced spine. This allows intervertebral device parameters, such as facet interference of intervertebral devices such as cages used in surgery, endplate contact, bone mineral density, and optimal shape (design, length, height, width, lordosis, kyphosis), to be determined in a manner known per se to obtain a desired balanced spine.

[0028] These intervertebral device parameters need to match components that are commercially available on the market, since the surgeon will select the device that is most compatible with the intervertebral device parameters calculated above from among devices that can be used for spinal fusion.

[0029] In a further step 70, the intervertebral device parameters are applied to the (complete or reconstructed) three-dimensional model of the spine in a manner known per se, thereby obtaining a corrected three-dimensional model of the spine.

[0030] In step 80, to ensure that the defined corrections are present in the X-ray image and the 3D model, the corrected 3D model of the spine is aligned with the 2D X-ray image, and the sagittal balance analysis performed in step 50 is updated as necessary. A second sagittal balance analysis is performed, thereby obtaining the corrected spinal-pelvic parameters (these parameters are corrected for the spinal-pelvic parameters calculated in step 50 thanks to the intervertebral structures of the 3D model of the spine). If the lordosis of the segment defined in step 50 does not change in the 3D model, the spinal-pelvic parameters remain the same as those previously calculated.

[0031] In step 90, the corrected spinal-pelvic parameters are compared to predetermined range values ​​reported in the literature to determine whether the desired balanced spine has been achieved.

[0032] If the result is positive, i.e., the corrected spinal-pelvic parameters are within such range values, the determined intervertebral device parameters can be used to design the corresponding intervertebral devices to be applied to the patient's spine during subsequent surgical procedures.

[0033] If negative, steps 60-90 are repeated until the correct intervertebral device parameters are obtained.

[0034] The process according to the present invention is performed by a system of the type shown in Figure 2, comprising a known type of workstation 200 having a processing subsystem 210, a display device 220, a keyboard 230, a pointing device (mouse) 240, and equipment for connecting to a local area network (network bus) 250. Alternatively, the processing system may be distributed (not shown) having a processing subsystem and local or remote peripheral input / output devices.

[0035] The workstation 200 or distributed system is configured to process computing programs and processing groups or modules that are stored on disk or accessible via a network and are suitable for displaying the described processes and showing the results to the device 220. The described solutions are considered to be well known to those skilled in the art and are therefore not relevant to the purpose and understanding of the present invention, and are not described herein.

[0036] Clearly, the principles, embodiments, and details of the manufacture of the present invention, which remain identical, can be substantially modified from those described and illustrated merely as non-limiting examples without departing from the scope of protection of the invention as defined in the appended claims.

Claims

1. A computer implementation method for determining the parameters of an intervertebral implant device for spinal fusion surgery, a) Step (10) The computer acquires a three-dimensional image of the patient's spine. b) Step (20) The computer calculates a three-dimensional model of the spine based on such three-dimensional images of the spine. c) Step (30) The computer acquires at least one two-dimensional image of the spine. d) Step (50) The computer performs a first sagittal balance of the three-dimensional model of the spine to calculate the spinal-pelvic parameters. e) step (60) the computer determines, based on the values ​​of the spine-pelvis parameters, intervertebral device parameters corresponding to the intervertebral devices to be used to obtain the patient's desired balanced spine; f) The computer applies the intervertebral device parameters to the three-dimensional model of the spine (70), thereby obtaining a corrected three-dimensional model of the spine. g) The computer compares the corrected three-dimensional model of the spine with the two-dimensional image (80), performs a second sagittal balance, and thus obtains corrected spinal-pelvic parameters. h) The computer compares the corrected spinal-pelvic parameters with a predetermined range of values ​​in order to determine whether the desired balanced spine has been obtained (90) i) If negative, a computer implementation method comprising the step of the computer repeating steps e)-h).

2. The computer implementation method for determining intervertebral implant device parameters according to claim 1, wherein the three-dimensional image of the spine is composed of an MRI image or a CT image.

3. A computer implementation method for determining intervertebral implant device parameters according to claim 1 or 2, wherein the at least one two-dimensional image comprises a lateral X-ray image and / or anterior-posterior X-ray images.

4. A computer implementation method for determining intervertebral implant device parameters according to claim 1 or 2, wherein the step (20) of the computer calculating a three-dimensional model of the spine includes the step (40) of the computer matching the two-dimensional image with the three-dimensional image.

5. The computer implementation method for determining intervertebral implant device parameters according to claim 4, wherein the step (40) of the computer matching the two-dimensional image with the three-dimensional image includes the step of the computer selecting a three-dimensional reconstructed image of a vertebra from a predefined database, the selected image having a predetermined match with the vertebra image of the two-dimensional image, and the matching (40) then includes the step of the computer combining the reconstructed image of the vertebra with the two-dimensional image to obtain a reconstructed three-dimensional model of the spine.

6. The computer implementation method for determining intervertebral implant device parameters according to claim 5, wherein the step of the computer combining the reconstructed image and the two-dimensional image of the vertebrae includes the step of the computer applying a DDR (digital reconstruction image) algorithm.

7. A computer implementation method for determining intervertebral implant device parameters according to claim 1 or 2, wherein the spinal-pelvic parameters include pelvic incline, sacral inclination, pelvic tilt, lumbar lordosis, thoracic kyphosis, and sagittal longitudinal axis.

8. A computer implementation method for determining intervertebral implant device parameters according to claim 1 or 2, wherein the intervertebral device parameters include facet interference of the intervertebral device, endplate contact, bone mineral concentration, and geometric shape.

9. A computer implementation method for determining the parameters of an intervertebral implant device according to claim 8, wherein the geometric shape includes the design, length, height, width, lordosis, and kyphosis of the intervertebral device.

10. A system for determining intervertebral implant device parameters for spinal fusion surgery, comprising a workstation (200) having a processing subsystem (210), wherein the processing subsystem (210) a) Obtain a three-dimensional image of the patient's spine (10), b) Based on such three-dimensional images of the spine, a three-dimensional model of the spine is calculated (20), c) Obtain at least one two-dimensional image of the spine (30), d) Perform a first sagittal balance on the three-dimensional model of the spine to calculate the spinal-pelvic parameters (50), e) Based on the values ​​of the spinal pelvic parameters, determine the intervertebral device parameters corresponding to the intervertebral device to be used to obtain the patient's desired balanced spine (60), f) Apply the intervertebral apparatus parameters to the three-dimensional model of the spine (70), thereby obtaining a corrected three-dimensional model of the spine. g) The corrected three-dimensional model of the spine is compared with the two-dimensional image (80), a second sagittal balance is performed, and in this way corrected spinal-pelvic parameters are obtained. h) To determine whether the desired balanced spine has been obtained, the corrected spinal-pelvic parameters are compared with a predetermined range of values ​​(90), i) If negative, the system is configured to repeat steps e)-h).

Images