Anatomical relationship between the accessory process of the lumbar spine and the pedicle screw entry point

Biportal endoscopic non-facetectomy foraminal decompression and discectomy (ligamentum flavum turn-down technique)

This study introduces a novel biportal endoscopic foraminal decompression technique that minimizes bone removal while ensuring safe and effective nerve root decompression. Leveraging the accessory process as a key surgical landmark, this technique enables precise navigation and controlled turn-down of the ligamentum flavum (LF). A key advantage of this technique is its reduced requirement for bone resection, differing from traditional microscopic or uniportal endoscopic surgeries that often necessitate resection of the lateral isthmus or superior articular process. This technique is particularly beneficial for foraminal and extraforaminal herniated nucleus pulposus cases, where bony decompression needs are relatively lower compared to foraminal stenosis. Using the accessory process as a landmark also enhances surgical precision and reduces the risk of nerve root injury, providing a valuable advantage for less experienced surgeons. Despite these advantages, challenges exist, particularly at the L5-S1 level, where the less prominent accessory process and limited workspace due to anatomical constraints can pose difficulties. In cases of severe bony compression, additional bone removal may be necessary to achieve adequate decompression. In conclusion, the Non-facetectomy LF turn-down technique (non-facetectomy foraminal decompression) offers a safe and effective minimally invasive alternative for treating various foraminal pathologies.

A novel method to evaluate the transverse pedicle angles of the lower lumbar vertebrae using digital radiography

To investigate a novel approach for establishing the transverse pedicle angle (TPA) of the lower lumbar spine using preoperative digital radiography (DR). Computed Tomography (CT) datasets of the lower lumbar were reconstructed using MIMICS 17.0 software and then imported into 3-matic software for surgical simulation and anatomical parameter measurement. A mathematical algorithm of TPA based on the Pythagorean theorem was established, and all obtained data were analyzed by SPSS software. The CT dataset from 66 samples was reconstructed as a digital model of the lower lumbar vertebrae (L3-L5), and the AP length/estimated lateral length for L3 between the right and left sides was statistically significant (P = 0.015, P = 0.005). The AP length of the right for L4 was smaller than that of the left after a paired t test was executed (P = 0.006). Both the width of the pedicle and the length of the pedicle (P2C1) were consistent with TPA (L3 Collapse

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MESH Headings

• Humans
• Lumbar Vertebrae/diagnostic imaging
• Male
• Tomography, X-Ray Computed/methods
• Female
• Middle Aged
• Adult
• Aged
• Algorithms
• Radiographic Image Enhancement/methods

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Grants

• Social Development Science and Technology Project of Shaanxi Province
• Education Department of Shaanxi Province
• Key Research and Development Projects of Shaanxi Province

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Affiliation(s)

Shixun Wu Department of Orthopedics Surgery, Shaanxi Provincial People’s Hospital, Xi’an, Shaanxi, China Key Laboratory of Bone Joint Disease Basic and Clinical Translation of Shaanxi Province, Xi’an, Shaanxi, China
Shizhang Liu Department of Orthopedics Surgery, Shaanxi Provincial People’s Hospital, Xi’an, Shaanxi, China Key Laboratory of Bone Joint Disease Basic and Clinical Translation of Shaanxi Province, Xi’an, Shaanxi, China
Ming Ling Department of Orthopedics Surgery, Shaanxi Provincial People’s Hospital, Xi’an, Shaanxi, China Key Laboratory of Bone Joint Disease Basic and Clinical Translation of Shaanxi Province, Xi’an, Shaanxi, China
Minggang Huang Department of Computed Tomography, Shaanxi Provincial People’s Hospital, Xi’an, Shaanxi, China
Zhe Liu Department of Computed Tomography, Shaanxi Provincial People’s Hospital, Xi’an, Shaanxi, China
Xianglong Duan Key Laboratory of Bone Joint Disease Basic and Clinical Translation of Shaanxi Province, Xi’an, Shaanxi, China Second Department of General Surgery, Shaanxi Provincial People’s Hospital, Xi’an, Shaanxi, China Institute of Medical Research, Northwestern Polytechnical University, Xi’an Shaanxi, China Second Department of General Surgery, Third Affiliated Hospital of Xi’an Jiaotong University, Xi’an, Shaanxi, China

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Posterior endpoint determination of the lumbar pedicle central axis on the anterior-posterior fluoroscopic image for pedicle screw insertion

The transpedicular procedure has been widely used in spinal surgery. The determination of the best entry point is the key to perform a successful transpedicular procedure. Various techniques have been used to determine this point, but the results are variable. This study was carried out to determine the posterior endpoint of the lumbar pedicle central axis on the standard anterior-posterior (AP) fluoroscopic images. Computer-aided design technology was used to determine the pedicle central axis and the posterior endpoint of the pedicle central axis on the posterior aspect of the vertebra. The standard AP fluoroscopic image of the lumbar vertebral models by three-dimensional printing was achieved. The endpoint projection on the AP fluoroscopic image was determined in reference to the pedicle cortex projection by the measurements of the angle and distance on the established X-Y coordinate system of the radiologic image. The projection of posterior endpoint of the lumbar pedicle central axis were found to be superior to the X-axis of the established X-Y coordinate system and was located on the pedicle cortex projection on the standard AP fluoroscopic image of the vertebra. The projection point was distributed in different sectors in the coordinate system. It was located superior to the X-axis by 18° to 26° at L1, while they were located superior to the X-axis by 12° to 14° at L2 to L5. The projections of posterior endpoints of the lumbar pedicle central axis were located in different positions on the standard AP fluoroscopic image of the vertebra. The determination method of the projection point was helpful for selecting an entry point for a transpedicular procedure with a fluoroscopic technique.

Sagittal imaging study of the lumbar spine with the short rod technique

PURPOSE

The short rod technique (SRT) is a novel method for lumbar pedicle screw placement to reduce surgical trauma and avoid damage to the facet joint and articular surface. The core concept is to change the entry point and angle of the screw on the vertebrae at both ends in the sagittal plane to shorten the length of the longitudinal rods. The purpose of this study is to determine the sagittal screw angle (SSA) and its safe Maximum (MAX) value on each lumbar vertebra for the SRT and to observe the shortening effect on the longitudinal rods.

METHODS

A total of 152 healthy adults were investigated by measuring the lumbar spine lateral view images. The SSA and MAX-SSA were measured with SRT as reference to the conventional placement technique method. The distance between the entry points of the proximal and distal vertebrae was measured to compare the changes in the length of the longitudinal rods using the two screw placement techniques.

RESULTS

 + SSA increased from L1 to L4, and -SSA increased from L2 to L5, in which the -SSA of L2, L3, and L4 were significantly greater than those of + SSA (P < 0.05). + MAX-SSA at L1-L4 was 23.26 ± 3.54°, 23.68 ± 3.37°, 24.12 ± 3.29°, and 24.26 ± 3.42°, respectively. -MAX-SSA at L2-L5 was 36.25 ± 3.26°, 38.26 ± 3.73°, 38.62 ± 3.63° and 37.33 ± 3.31°, respectively. Theoretical reductions by calculation for the 2-segment lumbar pedicles were: L1-2: 9 mm, L2-3: 9.29 mm, L3-4: 6.23 mm, and L4-5: 7.08 mm; And the 3-segment lumbar pedicles were: L1-3: 16.97 mm, L2-4: 16.73 mm, L3-5, and 18.24 mm, respectively.

CONCLUSIONS

The application of the SRT to lumbar pedicles is a safe screw placement method that can significantly shorten the length of the used longitudinal rods.