A method for determining the disc penetration depth in posterior lumbar interbody fusion

Abstract

The present invention relates to a method for determining the disc incision depth of posterior lumbar interbody fusion, comprising the following steps: (1) Selecting patients with lumbar degenerative diseases who have undergone X-ray examination and plain CT scan of lumbar intervertebral discs as samples; (2) Removing unqualified samples; (3) Taking anteroposterior and lateral X-rays of the lumbar spine with the patient standing, and performing tomographic scanning with the patient lying flat; (4) Measuring the lengths of the lower edges of the L3 (the third lumbar vertebra), L4 (the fourth lumbar vertebra), and L5 (the fifth lumbar vertebra) vertebral bodies in the X-ray films as the X-ray depths of the L3 / 4, L4 / 5, and L5 / S1 intervertebral spaces; (5) Performing statistical analysis using SPSS 18.0 software and making a table of the analysis results; (6) Obtaining the warning value of the disc incision depth based on the data results. This method provides the warning value of the insertion depth of the nucleus pulposus forceps for medical staff performing posterior lumbar interbody fusion, improving the safety and success rate of interbody fusion.

Description

Technical Field

[0001] The present invention relates to the field of intervertebral fusion, and particularly to a method for determining the disc cutting depth in posterior lumbar interbody fusion. Background Art

[0002] Lumbar spinal instability and low back and leg pain caused by lumbar disc degenerative diseases have always been a common and frequently-occurring disease that plagues patients, especially with a very high incidence in elderly patients. To solve this problem and improve the quality of life of patients, surgeons have designed and developed a variety of surgeries to remove the diseased intervertebral disc and promote lumbar fusion. The PLF (posterolateral lumbar fusion) surgery reported by Watkins in 1953, with the advantages of simple exposure, low surgical technical requirements, and a relatively low probability of nerve and dura mater injury during the operation, once became the most commonly used fusion surgery for treating lumbar degeneration and is even still in use today. However, since PLF only performs bone grafting between the transverse process and the lamina, the bone grafting bed area is small, and the incidence of non-fusion after surgery is relatively high. Therefore, Cloward et al. improved and designed the PLIF (posterior lumbar interbody fusion) surgery on the basis of PLF. This surgical method not only achieves 360° decompression of the spinal canal, but also provides intervertebral support and bone graft fusion after removing the diseased intervertebral disc, ensuring the restoration of the intervertebral height, increasing the bone graft area, and greatly improving the fusion rate. In addition, through the fixation of the posterior pedicle screw-rod system, PLIF reconstructs the mechanical stability of the spine and significantly reduces the probability of bone graft displacement and secondary lumbar instability. With these advantages, the PLIF surgery has become the most commonly used standard surgical method for treating lumbar disc degenerative diseases currently.

[0003] Although later scholars invented some new surgical methods such as TLIF (transforaminal lumbar interbody fusion), ALIF (anterior lumbar interbody fusion), OLIF (oblique lateral interbody fusion), XLIF (extreme lateral interbody fusion), etc. in order to avoid the possible injuries caused by the traction of the cauda equina nerve and nerve roots during PLIF surgery. However, these new surgical methods are restricted by the indications and have not replaced the status of the PLIF surgery.

[0004] For PLIF surgery, nerve decompression and reconstruction of the stability of the spinal segment have always been the two most core objectives. Nerve decompression can be achieved by opening the spinal canal, expanding the neural foramen, and removing the herniated intervertebral disc. However, relying solely on the fixation of the pedicle screw-rod system to reconstruct the stability of the spinal segment is unreliable because without bony fusion between the diseased segments, the internal fixation system will eventually fail. Therefore, removing the original degenerated intervertebral disc as much as possible, increasing the bone mass of interbody bone grafting, and improving the success rate of bony fusion between vertebral bodies have become the key factors for the success of PLIF surgery.

[0005] The path for removing the intervertebral disc in PLIF surgery is to open the spinal canal, retract the dura mater, incise the posterior longitudinal ligament on one side, and gradually remove the intervertebral disc from the posterior to the anterior. During this process, excessive retraction of the dura mater may cause traction injury to the corresponding segmental nerve roots or direct injury to the cauda equina. Therefore, it is generally recommended that the dura mater not be retracted beyond the midline of the spinal canal. This greatly limits the incision on the posterior longitudinal ligament, making it impossible to easily remove the intervertebral disc and properly handle the upper and lower endplates under direct vision through this incision. As a result, the entire removal process basically relies on personal experience and "feel". Once the depth of intervertebral disc resection is not well controlled and the anterior longitudinal ligament is breached and enters the abdominal cavity, it will damage the common iliac artery or abdominal organs in front of the vertebral body, leading to serious consequences such as massive bleeding, organ injury, and even death. Therefore, strictly controlling the incision depth of the intervertebral disc and finding a certain warning value will greatly improve the safety of PLIF surgery, facilitate the removal of more intervertebral discs, and thus increase the interbody fusion rate.

[0006] In summary, the present invention aims to find the warning value for the incision depth of the nucleus pulposus forceps in posterior lumbar interbody fusion surgery, reduce the dependence of medical staff on personal experience and feel when operating the nucleus pulposus forceps, and at the same time provide scientific data support for the production of new nucleus pulposus forceps to avoid serious consequences such as massive bleeding, organ injury, and even death caused by excessive incision depth of the nucleus pulposus forceps. Summary of the Invention

[0007] The present invention provides a method for determining the incision depth of the intervertebral disc in posterior lumbar interbody fusion surgery, including the following steps:

[0008] (1) Inclusion criteria for research samples: Select patients who are initially diagnosed with lumbar degenerative diseases in the outpatient clinic and have undergone anteroposterior and lateral lumbar X-ray examinations and plain CT scans of the lumbar intervertebral discs in the radiology department;

[0009] (2) Exclusion criteria for samples: Remove the samples in the samples that meet the following conditions,

[0010] 1. Less than 30 years old, 2. More than 70 years old, 3. Presence of spinal degenerative scoliosis and rotation, 4. Massive osteophyte hyperplasia, 5. Coexistence of osteoclastic diseases such as spinal tumors and tuberculosis, 6. Vertebral body slippage > III degree, 7. The lumbar intervertebral disc has undergone surgical treatment;

[0011] (3) Sample image acquisition: The patient's position is standing when irradiating the anteroposterior and lateral lumbar X-ray films, and the patient's position is lying flat when undergoing tomographic scanning;

[0012] (4) Sample measurement indicators:

[0013] Measure the depth of the intervertebral space in the X-ray film. Take the lateral lumbar X-ray film and measure the lengths of the lower edges of the L3 (the third lumbar vertebra), L4 (the fourth lumbar vertebra), and L5 (the fifth lumbar vertebra) vertebral bodies respectively, as the depths of the L3 / 4, L4 / 5, and L5 / S1 intervertebral spaces;

[0014] Measure the straight depth of the CT intervertebral space. Set the 1 / 4 of the transverse diameter of the spinal canal as the starting point, draw a perpendicular line to the transverse diameter line of the spinal canal through the starting point, and take the intersection point of this perpendicular line and the posterior edge of the image of the lower endplate of the vertebral body as point A and the intersection point with the anterior edge as point B. Measure the distance between points A and B of the L3, L4, and L5 vertebral bodies, respectively, as the CT straight depth of the L3 / 4, L4 / 5, and L5 / S1 intervertebral spaces;

[0015] Measure the oblique depth of the CT intervertebral space: Set the intersection point of the perpendicular line of the outer boundary of the spinal canal and the image of the apex of the facet joint as the maximum inclination point (point O). Connect point O and point A to make a straight line, and take the intersection point of the straight line and the anterior edge of the image of the lower endplate of the vertebral body as point C. Measure the distance between points A and C of the L3, L4, and L5 vertebral bodies, respectively, as the CT oblique depth of the L3 / 4, L4 / 5, and L5 / S1 intervertebral spaces;

[0016] (5) Sample statistical analysis: Use SPSS18.0 software for statistical analysis. Measurement data with normal distribution are expressed as mean ± standard deviation; Calculate the average values of the straight and oblique CT measurement values to describe the normal distribution; Statistically compare and analyze the differences in the depth of the intervertebral space between men and women in each segment, and the differences between the depth of the intervertebral space measured by X-ray film and the CT measurement values; The comparison uses paired sample t-test; P < 0.05 is considered statistically significant;

[0017] (6) Draw a conclusion: The warning value of the straight cutting depth of the intervertebral disc for posterior lumbar interbody fusion is 34 mm, and the warning value of the oblique cutting depth of the intervertebral disc for posterior lumbar interbody fusion is 36 mm.

[0018] Furthermore, in the step (5), the number of male and female samples is equal, and the total number is not less than 100 people.

[0019] Advantages of the invention

[0020] The proposed method solves the problem that when medical staff perform posterior lumbar interbody fusion surgery, the penetration depth of the nucleus pulposus forceps can only be judged on-site by hand feeling and personal experience, overturns the wrong idea of some medical staff using the X-ray measurement value as the reference value for the intervertebral space depth, provides a true and reliable measurement scheme for measuring the intervertebral space depth, provides a warning value for the penetration depth of the nucleus pulposus forceps for medical staff with insufficient clinical experience, can improve the success rate and safety of posterior lumbar interbody fusion surgery, and also provides scientific data support for the production of new nucleus pulposus forceps. From a physical perspective, it solves the situation where the nucleus pulposus forceps penetrate too deep and break through the anterior longitudinal ligament into the abdominal cavity, damaging the common iliac artery or abdominal organs in front of the vertebral body, resulting in massive bleeding, organ damage, or even death.

[0021] Explanatory drawings of the specification

[0022] Figure 1 Schematic diagram of the front view of the intervertebral disc resection for PLIF surgery;

[0023] Figure 2 Schematic diagram of the side view of the intervertebral disc resection for PLIF surgery;

[0024] Figure 3 Schematic diagram of the method for measuring the intervertebral space on the lateral lumbar X-ray film;

[0025] Figure 4 Schematic diagram of the straight path for resection of the intervertebral disc in PLIF;

[0026] Figure 5 Schematic diagram of the oblique path for resection of the intervertebral disc in PLIF;

[0027] Figure 6 Schematic diagram of the scheme for measuring the straight and oblique depths on CT images;

[0028] Figure 7 Schematic diagram of an actual case of CT image measurement. Detailed implementation manners

[0029] The present invention will be clearly and completely described below through specific implementation manners.

[0030] A method for determining the penetration depth of the intervertebral disc in posterior lumbar interbody fusion surgery according to the present invention includes the following steps:

[0031] (1) Inclusion criteria for research samples: Patients who were initially diagnosed with lumbar degenerative diseases in the outpatient department and had undergone anteroposterior and lateral lumbar X-ray examinations and plain lumbar intervertebral disc CT scans in the radiology department were selected. In this method, patients who visited the outpatient department of the Second People's Hospital of Yunnan Province from January 1, 2019, to December 31, 2019, were initially diagnosed with lumbar degenerative diseases, and who had completed examinations such as anteroposterior and lateral lumbar X-rays and plain lumbar intervertebral disc CT scans according to their conditions were selected;

[0032] (3) Exclusion criteria for samples: Samples that met the following conditions were removed: 1. Patients younger than 30 years old. Since it was considered that patients at a too young age were still in the growth and development stage, the width of the vertebral body was constantly changing, and the measured values could not be accurate; moreover, the incidence of lumbar degenerative diseases in patients under 30 years old was extremely low, the number of cases was very small, and the treatment was mainly conservative treatment, so the guiding significance of the measured values was not great, and thus they were excluded;

[0033] 2. Patients older than 70 years old. The probability of vertebral body deformation, osteophyte hyperplasia, vertebral body scoliosis and rotation in elderly patients was relatively high, making measurement difficult and the accuracy poor;

[0034] 3. Presence of spinal degenerative scoliosis and rotation;

[0035] 4. Massive osteophyte hyperplasia;

[0036] 5. Coexistence of osteoclastic diseases such as spinal tumors and tuberculosis;

[0037] 6. Intervertebral body slippage > grade III;

[0038] 7. History of surgical treatment for lumbar intervertebral disc;

[0039] According to the inclusion and exclusion criteria, the imaging data of 100 patients (50 males / 50 females) were randomly selected, and the results of X-ray films and CT films were measured respectively. Among these 100 patients, the average age of the male group was 59.0 years old (35 - 70 years old), and that of the female group was 59.0 years old (35 - 70 years old). When comparing the age compositions of the two groups of patients, the difference was not statistically significant (P > 0.05), as shown in Table 1 for details.

[0040] Table 1 Age differences between male and female groups

[0041]

[0042] (3) Sample image acquisition: The patient's position was standing when irradiating the anteroposterior and lateral lumbar X-ray films, and the patient's position was lying flat when undergoing tomographic scanning;

[0043] (4) Sample measurement indicators (such as Figures 1 to 7 )

[0044] Depth of intervertebral space on X-ray: Take a lateral X-ray of the lumbar spine and measure the length of the lower edge of the L3 (third lumbar vertebra), L4 (fourth lumbar vertebra), and L5 (fifth lumbar vertebra) vertebrae respectively, as the depth of the L3 / 4, L4 / 5, and L5 / S1 intervertebral spaces;

[0045] CT intervertebral disc vertical depth: Since the distance of dura mater retraction reaches the midline of the spinal canal at most, the exposure and operation range is only half of the anterior wall of the spinal canal (the side of the surgical operation). In this operation area, the posterior longitudinal ligament is routinely cut from the midline, and then the anterior intervertebral disc is processed. Therefore, when measuring the vertical intervertebral disc depth, set 1 / 4 of the transverse diameter of the spinal canal as the starting point, draw a vertical line through the starting point, and use the intersection of this vertical line with the posterior edge of the image of the lower end plate of the vertebral body as point A, and the intersection with the anterior edge as point B. Measure the distance between the AB points of the L3, L4, and L5 vertebrae, which are used as the CT vertical depth of the L3 / 4, L4 / 5, and L5 / S1 intervertebral discs, respectively.

[0046] CT oblique depth of intervertebral space: During PLIF surgery, the facet joints and some lateral lamina structures are retained, resulting in the restriction of the inclination angle of the nucleus pulposus forceps and other resection tools when the intervertebral disc is removed from the posterior longitudinal ligament incision to the opposite side. Therefore, the intersection of the vertical line of the lateral boundary of the spinal canal and the facet joint vertex image is set as the maximum inclination point (0 point), and a straight line is drawn from point 0 to point A. The point where the straight line intersects with the front edge of the lower endplate image of the vertebral body is taken as point C. The distance between the AC points of the L3, L4, and L5 vertebrae is measured as the CT oblique depth of the L3 / 4, L4 / 5, and L5 / S1 intervertebral spaces, respectively.

[0047] (5) Sample statistical analysis: SPSS 18.0 software was used for statistical analysis. Normally distributed quantitative data were expressed as mean ± standard deviation. The average values of the vertical and oblique CT measurements were calculated to describe the normal distribution. The differences in the intervertebral depth of each segment, as well as the differences between the intervertebral depth measured by X-ray and the CT measurement were statistically compared and analyzed. The comparison was performed using the paired sample t test. P < 0.05 was considered statistically significant.

[0048] 1. Difference between the intervertebral depth of lumbar lateral X-ray and the vertical depth of intervertebral depth of CT

[0049] The intervertebral depth measured on the lateral lumbar X-ray and the vertical depth of the intervertebral depth on the CT of all patients at L3 / 4, L4 / 5, and L5 / S1 were compared statistically, and the difference between the two groups of data was statistically significant (P < 0.05). There was an error between the intervertebral depth measured on the lateral lumbar X-ray and the vertical depth of the intervertebral depth measured on the CT. See Table 2 for details.

[0050] Table 2 Differences in intervertebral depth measured on lateral lumbar X-rays and vertical intervertebral depth measured on CT images (unit: mm)

[0051]

[0052] 2. Differences in the straight and oblique depths of the intervertebral spaces on lumbar spine CT scans

[0053] Analysis of the differences in the straight and oblique depths of the intervertebral spaces on lumbar spine CT scans measured in all patients showed that the differences between the two sets of data were statistically significant (P < 0.05). The oblique depth of the intervertebral space in each segment was indeed deeper than the straight depth (by approximately 2 mm). See Table 3 for details

[0054] Table 3 Differences in the straight and oblique depths of the intervertebral spaces on lumbar spine CT scans (unit: mm)

[0055]

[0056] 3. Differences in the straight and oblique depths of the intervertebral spaces between segments on lumbar spine CT scans

[0057] Analysis of the differences in the straight and oblique depths of the intervertebral spaces on lumbar spine CT scans measured in all patients among three segments showed that the differences between the three sets of data were not statistically significant (P > 0.05). The depths of the L3 / 4, L4 / 5, and L5 / S1 intervertebral spaces were not very different and were basically similar. See Table 4 for details

[0058] Table 4 Differences in the straight and oblique depths of the L3 / 4 and L4 / 5 intervertebral spaces on lumbar spine CT scans measured (unit: mm)

[0059]

[0060] (6) Draw the conclusion: The warning value for the straight cutting depth of the intervertebral disc during posterior lumbar interbody fusion is 34 mm, and the warning value for the oblique cutting depth of the intervertebral disc during posterior lumbar interbody fusion is 36 mm.

Claims

1. A method for measuring the disc incision depth of posterior lumbar interbody fusion based on CT images, characterized in that: It includes the following steps: (1) Inclusion criteria for research samples: Select patients who were initially diagnosed with lumbar degenerative diseases in the outpatient department and had undergone anteroposterior and lateral lumbar X-ray examinations and plain lumbar intervertebral disc CT scans in the radiology department. (2) Exclusion criteria for samples: Remove the samples in the samples that meet the following conditions.

1. Age less than 30 years old; 2. Age greater than 70 years old; 3. Presence of spinal degenerative scoliosis and rotation; 4. Massive osteophyte hyperplasia; 5. Coexistence of osteoclastic diseases such as spinal tumors and tuberculosis; 6. Intervertebral body slippage > grade III; 7. The lumbar intervertebral disc has undergone surgical treatment. (3) Sample image acquisition: The patient's position is standing when irradiating the anteroposterior and lateral lumbar X-rays, and the patient's position is lying flat when performing tomographic scans. (4) Sample measurement indicators: Measure the depth of the intervertebral space in the X-ray film. Take the lateral lumbar X-ray film and measure the lengths of the lower edges of the L3 (the third lumbar vertebra), L4 (the fourth lumbar vertebra), and L5 (the fifth lumbar vertebra) vertebral bodies respectively, as the depths of the L3 / 4, L4 / 5, and L5 / S1 intervertebral spaces. Measure the straight depth of the CT intervertebral space. Set 1 / 4 of the transverse diameter of the spinal canal as the starting point, draw a perpendicular line to the transverse diameter line of the spinal canal through the starting point, and take the intersection point of this perpendicular line and the posterior edge of the image of the lower endplate of the vertebral body as point A and the intersection point with the anterior edge as point B. Measure the distance between points A and B of the L3, L4, and L5 vertebral bodies respectively, as the straight depth of the CT of the L3 / 4, L4 / 5, and L5 / S1 intervertebral spaces. Measure the oblique depth of the CT intervertebral space: Set the intersection point of the perpendicular line of the outer boundary of the spinal canal and the image of the apex of the facet joint as the maximum inclination point (point O). Connect point O and point A to make a straight line, and take the intersection point of the straight line and the anterior edge of the image of the lower endplate of the vertebral body as point C. Measure the distance between points A and C of the L3, L4, and L5 vertebral bodies respectively, as the oblique depth of the CT of the L3 / 4, L4 / 5, and L5 / S1 intervertebral spaces. (5) Statistical analysis of samples: Use SPSS18.0 software for statistical analysis. Measurement data with normal distribution are expressed as mean ± standard deviation; calculate the average values of the straight and oblique CT measurement values to describe the normal distribution; perform statistical comparison and analysis on the differences in the depths of the intervertebral spaces of each segment and the differences between the depths of the intervertebral spaces measured by X-ray films and the CT measurement values; the comparison uses paired sample t-tests. P < 0.05 indicates that the difference is statistically significant. (6) Draw conclusions: The warning value for the straight cutting depth of the intervertebral disc during posterior lumbar interbody fusion is 34 mm, and the warning value for the oblique cutting depth of the intervertebral disc during posterior lumbar interbody fusion is 36 mm.

2. The method for measuring the disc incision depth of posterior lumbar interbody fusion based on CT images according to claim 1, wherein: In step (5) described above, the number of male and female samples is equal, and the total number is not less than 100 people.

Images