Posterior Pedicle Screw Fixation Research Articles

Effective method of pedicle screw fixation in patients with neurologically intact thoracolumbar burst fractures: a systematic review of studies published over the last 20 years

ObjectiveTo conduct a systematic review of studies on various posterior pedicle screw fixation (PSF) methods used for treating neurologically intact thoracolumbar burst fractures and to identify the most effective and safe approaches. MethodsWe conducted a systematic review adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, with the study registered in PROSPERO (CRD42024531093). The inclusion criteria were: (1) publication dates from January 1, 2004, to December 31, 2023; (2) availability of full-text articles in English; (3) thoracolumbar burst fractures without neurological deficits; (4) patients aged over 18; (5) reports on treatment outcomes or complications; (6) a mean follow-up period of at least 12 months. ResultsA total of 69 articles covering 116 patient groups were included. Our analysis highlighted the advantages of short-segment fixation without fusion over monosegmental, short-segment and long-segment fusion in terms of shorter operation times and reduced intraoperative blood loss (p = 0.001 and p < 0.001, respectively). Extensive fusion was associated with a significantly higher frequency of deep surgical site infections compared to other PSF methods (p = 0.043). Percutaneous pedicle screw fixation, applied to patients with lower body compression rates and kyphotic deformities, led to less potential for correction (p = 0.004), yet significantly decreased blood loss (p = 0.011), operation duration (p < 0.0001), and hospitalization duration (p < 0.0001). No significant benefits were observed with the use of additional intermediate screws in short-segment PSF. ConclusionsShort-segment pedicle screw fixation could be the optimal surgical treatment method for neurologically intact thoracolumbar burst fractures. The use of posterior lateral fusion in this context may increase the deep surgical site infection rate without reducing the frequency of implant-related complications or improving long-term treatment outcomes. The percutaneous approach remains the preferred technique; however, its limited reduction capabilities should be carefully considered during surgical planning for patients with severe kyphotic deformities. The application of intermediate screws in such patients has not demonstrated significant advantages. Removing the fixation system has not led to a significant decrease in implant-related complications or improvement in quality of life. The data obtained from the systematic review may assist surgeons in selecting the most appropriate surgical treatment method for patients with neurologically intact thoracolumbar burst fractures, thereby avoiding ineffective procedures and improving both short-term and long-term outcomes.

How I do it: en-bloc thoracic vertebrectomy.

Some young patients with preserved functional status suffering from aggressive isolated neoplastic disease of the thoracic spine may be eligible from curative en-bloc vertebrectomy surgical treatment. Long-segment posterior pedicle screw fixation is performed. Complete excision of the posterior arch and of ribs posterior aspect is performed. Finger blunt dissection is performed between vertebral body, pleura, and aorta allowing to place a soft abdominal valve and then Gigli saws surrounding the anterior aspect of the spine, in order to saw the upper and the lower discs. Unilateral temporary rod is placed. The vertebral body is dislodged from posterior ligament and then removed by circling laterally around spinal cord. An expandable vertebral implant is placed. Posterior en-bloc thoracic vertebrectomy is a highly technical yet achievable procedure which carries a curative intent for isolated neoplastic spine lesions.

Reasons and strategies of reoperation after oblique lateral interbody fusion

To summarize the reasons and management strategies of reoperation after oblique lateral interbody fusion (OLIF), and put forward preventive measures. From October 2015 to December 2019, 23 patients who underwent reoperation after OLIF in four spine surgery centers were retrospectively analyzed. There were 9 males and 14 females with an average age of (61.89±8.80) years old ranging from 44 to 81 years old. The index diagnosis was degenerative lumbar intervertebral dics diseases in 3 cases, discogenic low back pain in 1 case, degenerative lumbar spondylolisthesis in 6 cases, lumbar spinal stenosis in 9 cases and degenerative lumbar spinal kyphoscoliosis in 4 cases. Sixteen patients were primarily treated with Stand-alone OLIF procedures and 7 cases were primarily treated with OLIF combined with posterior pedicle screw fixation. There were 17 cases of single fusion segment, 2 of 2 fusion segments, 4 of 3 fusion segments. All the cases underwent reoperation within 3 months after the initial surgery. The strategies of reoperation included supplementary posterior pedicle screw instrumentation in 16 cases;posterior laminectomy, cage adjustment and neurolysis in 2 cases, arthroplasty and neurolysis under endoscope in 1 case, posterior laminectomy and neurolysis in 1 case, pedicle screw adjustment in 1 case, exploration and decompression under percutaneous endoscopic in 1 case, interbody fusion cage and pedicle screw revision in 1 case. Visual analogue scale (VAS) and Oswestry disability index (ODI) index were used to evaluate and compare the recovery of low back pain and lumbar function before reoperation and at the last follow-up. During the follow-up process, the phenomenon of fusion cage settlement or re-displacement, as well as the condition of intervertebral fusion, were observed. The changes in intervertebral space height before the first operation, after the first operation, before the second operation, 3 to 5 days after the second operation, 6 months after the second operation, and at the latest follow-up were measured and compared. There was no skin necrosis and infection. All patients were followed up from 12 to 48 months with an average of (28.1±7.3) months. Nerve root injury symptoms were relieved within 3 to 6 months. No cage transverse shifting and no dislodgement, loosening or breakage of the instrumentation was observed in any patient during the follow-up period. Though the intervertebral disc height was obviously increased at the first postoperative, there was a rapid loss in the early stage, and still partially lost after reoperation. The VAS for back pain recovered from (6.20±1.69) points preoperatively to (1.60±0.71) points postoperatively(P<0.05). The ODI recovered from (40.60±7.01)% preoperatively to (9.14±2.66)% postoperatively(P<0.05). There is a risk of reoperation due to failure after OLIF surgery. The reasons for reoperation include preoperative bone loss or osteoporosis the initial surgery was performed by Stand-alone, intraoperative endplate injury, significant subsidence of the fusion cage after surgery, postoperative fusion cage displacement, nerve damage, etc. As long as it is discovered in a timely manner and handled properly, further surgery after OLIF surgery can achieve better clinical results, but prevention still needs to be strengthened.

3D printing navigation template assisted pedicle screw placement for the treatment of typeⅡold odontoid fractures

To compare the safety and clinical efficacy of freehand and 3D printing navigation template assisted screw placement in patients with old odontoid fractures of typeⅡ. Total of 38 patients with old odontoid fractures of typeⅡwere treated from November 2018 to December 2022, all of which presented as chronic neck pain. According to the different methods of screw insertion into the pedicle, the patients were divided into a navigation template group and a freehand group. In the navigation template group, there were 17 patients including 9 males and 8 females with an average age of (51.30±13.20) years old, disease duration was (22.18±7.59) months. In the freehand group, there 21 patients including 7 males and 14 females with an average age of (49.46±11.92) years old, disease duration was (19.52±9.17) months. The intraoperative blood loss, operation time, and postoperative drainage output were recorded and compared between two groups. The accuracy of screw placement was evaluated by CT scan. Before operation and 1 year after operation, cervical pain was assessed by visual analogue scale(VAS), neurological changes were evaluated by the Japanese Orthopaedic Association (JOA) score, and the degree of spinal cord injury was assessed by the American Spinal Injury Association (ASIA) injury scale. All patients were followed up for (25.31±1.21) months. The operation time of template group (112.00±20.48) min had significantly shorter than that of the freehand group(124.29±15.24) min(P<0.05), while there were no significant differences between two groups in terms of intraoperative blood loss, postoperative drainage, and hospital stay(P>0.05). At 1 year after operation, in template group and freehand group, the VAS [(2.88±0.86), (2.90±0.83)] and JOA [(14.94±1.82), (14.62±2.19)] improved with preoperative [VAS(4.71±0.92), (4.86±0.79) and JOA (12.18±2.30), (11.95±2.31)](P<0.05), with no significant difference between two groups (P>0.05). No significant improvement was observed in ASIA grading in either group at 1 year after operation(P>0.05), and there was no significant difference between two groups(P>0.05). The template group had significantly better accuracy of screw placement in the pedicle of the axis than the freehand group (P<0.05), while no significant difference was observed between two groups in the accuracy of screw placement in the pedicle of the atlas (P>0.05). In the treatment of typeⅡold odontoid fractures with posterior pedicle screw fixation, 3D printing navigation template screw placement can significantly shorten the operation time, achieve similar clinical efficacy as free-hand screw placement, and significantly improve the accuracy of screw placement in the pedicle of the axis.

Accuracy and Safety of Freehand Placement of Upper Thoracic Pedicle Screws Supported Solely by Anteroposterior, i.e., Frontal, X-Ray Fluoroscopy (C-Arm): Technical Note Including 23 Patients

IntroductionThe biomechanical resistance and the surgical morbidity of spinal posterior pedicle screw fixation relies on the intraosseous position of the implants. Upper thoracic pedicle screws are particularly demanding given their convergence and thin character. We present our experience as military surgeons of free hand placement of upper thoracic pedicle screws supported by antero-posterior, i.e. frontal X-ray fluoroscopy solely. Materials and methodsMonocentric retrospective analysis at Sainte-Anne Military Teaching Hospital between 2017 and 2024 of patients operated on using upper thoracic pedicle screws (levels T1 to T5) using antero-posterior fluoroscopy solely. Results23 patients were included (mean age 59, male/female 3.6), 16 traumas and 7 neoplastic lesions), with 15 cervicothoracic junction fixation and 8 upper thoracic spine surgeries. 124 screws were inserted (T1 to T5). 85% (106/124) were graded 0 (Gertzbein-Robbins scale) whereas 14.5% (18/124) displayed some degree of misplacement (grade 1 to 3): all the T1 screws (22/22) were accurately placed compared to 83% (20/24) of T2 screws, 88% (30/34) of T3 screws, 85% (17/20) of T4 screws, and finally 71% (17/24) of T5 screws, without any clinical consequences. There were 3 surgical revisions (1 asymptomatic misplaced screw, 2 mechanical failures in trauma). Last, 92.7% (n=51/55) of the screws inserted during working hours were accurately placed compared to 79.7% (n=55/69) during after-hours surgeries (p=0.039) ConclusionClinically speaking, placement of upper thoracic pedicle screws using antero-posterior fluoroscopy solely appears safe. The surgical technique is simple enough to be used in strained resources settings such as a mobile field surgical team.

A Prediction Nomogram for Fractured Vertebra Recollapse After Posterior Reduction and Pedicle Screw Fixation in Thoracolumbar Fractures

This study aimed to establish a predictive nomogram model for recollapse of fractured vertebra after posterior pedicle screw fixation in thoracolumbar fractures (TLFs). Patients undergoing posterior pedicle screw fixation for TLFs at our hospital between January 2016 and December 2021 were retrospectively reviewed. Patients were divided into 2 groups according to the presence or absence of recollapse of the fractured vertebra at the final follow-up. The predictors for fractured vertebra recollapse were identified by univariate and multivariable logistic regression analysis, and a nomogram model was developed. The prediction performance and internal validation were established. A total of 224 patients were included in this study. Of these, 46 (20.5%) patients developed recollapse of fractured vertebra. Age, thoracic and lumbar injury severity score, screw distribution in the fractured vertebra, and anterior vertebral height compression ratio were associated with vertebral recollapse. These predictors were used to construct a predictive nomogram. The area under the receiver operating characteristic curve of the nomogram model was 0.891. The concordance index was 0.891, and it was 0.877 with bootstrapping validation. The calibration curves and decision curve analysis also suggested that the nomogram model had excellent predictive performances for fractured vertebra recollapse. A clinical nomogram incorporating 4 variables was constructed to predict fractured vertebra recollapse after posterior pedicle screw fixation for TLFs. The nomogram demonstrated good calibration and discriminative abilities, which may help clinicians to make better treatment decisions.

Effective method of pedicle screw fixation in patients with neurologically intact thoracolumbar burst fractures: a systematic review of studies published over the last 20 years

ObjectiveTo conduct a systematic review of studies on various posterior pedicle screw fixation (PSF) methods used for treating neurologically intact thoracolumbar burst fractures and to identify the most effective and safe approaches. MethodsWe conducted a systematic review adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, with the study registered in PROSPERO (CRD42024531093). The inclusion criteria were: (1) publication dates from January 1, 2004, to December 31, 2023; (2) availability of full-text articles in English; (3) thoracolumbar burst fractures without neurological deficits; (4) patients aged over 18; (5) reports on treatment outcomes or complications; (6) a mean follow-up period of at least 12 months. ResultsA total of 69 articles covering 116 patient groups were included. Our analysis highlighted the advantages of short-segment fixation without fusion over monosegmental, short-segment and long-segment fusion in terms of shorter operation times and reduced intraoperative blood loss (p = 0.001 and p < 0.001, respectively). Extensive fusion was associated with a significantly higher frequency of deep surgical site infections compared to other PSF methods (p = 0.043). Percutaneous pedicle screw fixation, applied to patients with lower body compression rates and kyphotic deformities, led to less potential for correction (p = 0.004), yet significantly decreased blood loss (p = 0.011), operation duration (p < 0.0001), and hospitalization duration (p < 0.0001). No significant benefits were observed with the use of additional intermediate screws in short-segment PSF. ConclusionsShort-segment pedicle screw fixation could be the optimal surgical treatment method for neurologically intact thoracolumbar burst fractures. The use of posterior lateral fusion in this context may increase the deep surgical site infection rate without reducing the frequency of implant-related complications or improving long-term treatment outcomes. The percutaneous approach remains the preferred technique; however, its limited reduction capabilities should be carefully considered during surgical planning for patients with severe kyphotic deformities. The application of intermediate screws in such patients has not demonstrated significant advantages. Removing the fixation system has not led to a significant decrease in implant-related complications or improvement in quality of life. The data obtained from the systematic review may assist surgeons in selecting the most appropriate surgical treatment method for patients with neurologically intact thoracolumbar burst fractures, thereby avoiding ineffective procedures and improving both short-term and long-term outcomes.

Computational study of a dorsolumbar complete burst fracture and its fixation methods

PurposeDuring a fall, a significant part of the major forces is absorbed by the dorsolumbar column area. When the applied stresses exceed the yield strength of the bone tissue, fractures can occur in the vertebrae. Vertebral fractures constitute one of the leading causes of trauma-related hospitalizations, accounting for 15% of all admissions. Posterior pedicle screw fixation has become a common method for treating burst fractures. However, physicians remain divided on the number of fixed segments that are needed to improve clinical outcomes. The present work aims to understand the biomechanical impact of different fixation methods, improving surgical treatments.Design/methodology/approachA finite element model of the dorsolumbar spine (T11–L3) section, including cartilages, discs and ligaments, was created. The dorsolumbar stability was tested by comparing two different surgical orthopedic treatments for a fractured first lumbar vertebra on the L1 vertebra: the posterior short segment fixation with intermediate screws (PSS) and the posterior long segment fixation (PL). Distinct loads were applied to represent daily activities.FindingsResults show that both procedures provide acceptable segment fixation, with the PL offering less freedom of movement, making it more stable than the PSS. The PL approach can be the best choice for an unstable fracture as it leads to a stiffer spine segment.Originality/valueThis study introduces a novel computational model designed for the biomechanical analysis of dorsolumbar injuries, aiming to identify the optimal treatment approaches within both clinical and surgical contexts.

A Novel Leverage Technique Using Monoaxial Pedicle Screw for Reduction of Thoracolumbar Compression Fractures: Surgical Technique and Analysis of Radiological Parameters.

Thoracolumbar compression fractures resulting from high-energy injuries are a common type of spinal fracture. Satisfying reduction of compressive vertebra body is essential for the clinical outcome. However, traditional distraction technique may lead to complications including pedicle screw loosening, pedicle screw breakage, and postoperative back pain because of excessive distraction. In this study, we reported a novel technique for reduction. Additionally, the effect and postoperative radiological parameters of this technique were compared with those of traditional distraction technique. The clinical data of 80 patients who had been treated with posterior pedicle screw fixation from January 2019 to December 2020 was retrospectively analyzed. Thirty-six patients were performed with the leverage technique, while 22 patients were treated with the traditional distraction technique. When pedicle screw fixation was performed with either the leverage technique or the traditional distraction technique, fracture reduction was completed with monoaxial pedicle screws using either the leverage maneuver or distraction of adjacent vertebrae. Clinical evaluation, including operation time, hospital stay, blood loss volume, and postoperative complications were collected. The American Spinal Injury Association (ASIA) score for neurological condition and the visual analog scale (VAS) score for pain were used to evaluate the patients' functional outcome. The radiographic analysis included local kyphotic angle (LKA), regional kyphotic angle (RKA), anterior vertebral height (AVH), posterior vertebral height (PVH), and sagittal compression (SC). The student t-test and the χ2-test (or the Fisher exact test) were used to compare the outcome measures between the two groups. The leverage group comprised 36 patients, while 44 patients were included in the distraction group. No statistically significant differences were found in the demographic data. The VAS score in the leverage group (3.0 ± 0.8) was significantly lower than that in the distraction group (4.2 ± 0.6) on postoperative day 1. Total correction of the LKA in the leverage group (11.5 ± 2.5°) was significantly higher than that in the distraction group (7.1 ± 1.3°) (p = 0.0004). Total correction of the RKA was higher in the leverage group (12.1 ± 4.3°) than in the distraction group (6.1 ± 0.9°) (p = 0.005). The ratio of rear pillar /front pillar correction was 0.35 ± 0.13 and 0.89 ± 0.18 in the leverage and distraction groups, respectively (p = 0.014). Total correction of the upper and lower foraminal height in the leverage group was significantly less than that in the distraction group. The leverage group had significantly higher correction of the upper and lower intervertebral space height than the distraction group. Our novel leverage technique provided better kyphotic reduction and restoration than compared to conventional distraction technique in the surgical treatment of thoracolumbar compression fractures.

Feasibility and safety report on robotic assistance for cervical pedicle screw fixation: a cadaveric study

This cadaveric study aimed to evaluate the safety and usability of a novel robotic system for posterior cervical pedicle screw fixation. Three human cadaveric specimens and C2-T3 were included. Freshly frozen human cadaver specimens were prepared and subjected to robot-assisted posterior cervical pedicle screw fixation using the robotic system. The accuracy of screw placement, breach rate, and critical structure violations were evaluated. The results were statistically compared with those of previous studies that used different robotic systems for cervical pedicle screw fixation. The robotic system demonstrated a high accuracy rate in screw placement. A significant number of screws were placed within predetermined safe zones. The total entry offset was 1.08 ± 0.83 mm, the target offset was 1.86 ± 0.50 mm, and the angle offset was 2.14 ± 0.77°. Accuracy rates comparable with those of previous studies using different robotic systems were achieved. The system was also feasible, allowing precise navigation and real-time feedback during the procedure. This cadaveric study validated the safety and usability of the novel robotic system for posterior cervical pedicle screw fixation. The system exhibited high precision in screw placement, and the results support the extension of the indications for robot-assisted pedicle screw fixation from the lumbar spine to the cervical spine.

Thoracolumbar fractures patients undergoing posterior pedicle screw fixation can benefit from drainage.

To explore whether it is necessary to put drain tubes after posterior pedicle screw fixation of thoracolumbar fractures. From April 2020 to January 2023, a total of 291 patients with recent thoracolumbar fractures (AO type-A or type-B) who received the pedicle screw fixation operation were enrolled retrospectively. In 77 patients, drain tubes were used in the pedicle screw fixation surgery, while no drain tubes were placed in the other group. After gleaning demographic information and results of lab examination and imageology examination, all data were put into a database. Independent-sample t-tests, Pearson Chi-Square tests, Linear regression analysis, and correlation analysis were then performed. Compared to the control group, the drainage group had significantly lower postoperative CRP levels (P = 0.047), less use of antipyretics (P = 0.035), higher ADL scores (P = 0.001), and lower NRS scores (P < 0.001) on the 6th day after surgery. Other investigation items, such as demographic information, operation time, intraoperative blood loss, body temperature, and other preoperative and postoperative lab results, showed no significant differences. The use of a drain tube in the pedicle screw fixation of thoracolumbar fractures is correlated with the improvement of patients' living and activity ability and the reduction of inflammation, postoperative fever and pain.

Percutaneous kyphoplasty with or without posterior pedicle screw fixation for the management of severe osteoporotic vertebral compression fractures with nonunion

ObjectiveTo assess the radiographic outcomes, clinical outcomes and complications of percutaneous kyphoplasty (PKP) with and without posterior pedicle screw fixation (PPSF) in the treatment of severe osteoporotic vertebral compression fractures (sOVCF) with nonunion.MethodsThis study involved 51 patients with sOVCF with nonunion who underwent PKP or PPSF + KP. The operation time, intraoperative blood loss, volume of injected bone cement, operation costs and hospital stays were all recorded. In addition, the Visual Analogue Scale (VAS) and the Oswestry Disability Index (ODI) were assessed separately for each patient before and after surgery.ResultsCompared with the PPSF + KP group, the PKP group had shorter operation time, less intraoperative blood loss, shorter hospital stays and fewer operation costs. However, cobb’s angle improvement (13.4 ± 4.3° vs. 21.4 ± 5.3°), VWR improvement ratio (30.4 ± 11.5% vs. 52.8 ± 12.7%), HA (34.9 ± 9.0% vs. 63.7 ± 7.6%) and HM (28.4 ± 11.2% vs. 49.6 ± 7.7%) improvement ratio were all higher in PPSF + KP group than that in PKP group. In addition, the ODI index and VAS score in both groups were significantly decreased at the postoperative and final follow-up. PKP group's postoperative VAS score was significantly lower than that in PPSF + KP group, but there was no statistically significant difference in VAS score at the last follow-up.ConclusionPKP and PPSF + KP can both effectively relieve the pain associated with sOVCF with nonunion. PPSF + KP can achieve more satisfactory vertebral reduction effects compared to PKP. However, PKP was less invasive and it has more advantages in shortening operation time and hospital stay, as well as decreasing intraoperative blood loss and operation costs.

Research into the anatomy of the subaxial cervical pedicle for ensuring screw insertion safety.

The study aimed to determine the optimal entry points and trajectories for posterior subaxial cervical pedicle screw (CPS) fixation. Computed tomography (CT) and Mimics software were used to evaluate the subaxial cervical pedicle in 42 cervical spine CT scans. The width of the cervical pedicle was measured and compared at medial angulations of 30°, 35°, 40°, 45°, 50°, 55°, and 60° relative to the midline sagittal plane. Based on an observational examination of the positions of all cervical 3-dimensional models and screws, the proposed entry point for C3-7 CPS was analyzed. Although the variations in C3-6 pedicle width (PW) among 45°, 50°, and 55° were not statistically significant, they were significantly larger than the differences among 30°, 35°, 40°, and 60° angles (P < .05). The differences in C7 PW between the 30°, 35°, 40°, and 45° angles were not statistically different even though the 30°, 35°, 40°, and 45° angles were significantly bigger. (P < .05). The proposed entry point for C3-7 CPS was below the junction of the lateral and lower borders of the superior articular process joint surface. The entry point for C3-7 levels was below the junction of the lateral and lower borders of the superior articular process joint surface. The optimal medial angulation for the posterior C3-6 CPS was 45°-55° and that for the posterior C7 CPS was 30°-45°. The sagittal angle of the posterior C3-7 CPS was parallel to the corresponding upper endplate.

Biomechanical evaluation of different oblique lumbar interbody fusion constructs: a finite element analysis

BackgroundFinite element analysis (FEA) was performed to investigate the biomechanical differences between different adjunct fixation methods for oblique lumbar interbody fusion (OLIF) and to further analyze its effect on adjacent segmental degeneration.MethodsWe built a single-segment (Si-segment) finite element model (FEM) for L4-5 and a double-segment (Do-segment) FEM for L3-5. Each complete FEM was supplemented and modified, and both developed two surgical models of OLIF with assisted internal fixation. They were OLIF with posterior bilateral percutaneous pedicle screw (TINA system) fixation (OLIF + BPS) and OLIF with lateral plate system (OLIF + LPS). The range of motion (ROM) and displacement of the vertebral body, cage stress, adjacent segment disc stress, and spinal ligament tension were recorded for the four models during flexion/extension, right/left bending, and right/left rotation by applying follower load.ResultsFor the BPS and LPS systems in the six postures of flexion, extension, right/left bending, and right/left rotation, the ROM of L4 in the Si-segment FEM were 0.32°/1.83°, 0.33°/1.34°, 0.23°/0.47°, 0.24°/0.45°, 0.33°/0.79°, and 0.34°/0.62°; the ROM of L4 in the Do-segment FEM were 0.39°/2.00°, 0.37°/1.38°, 0.23°/0.47°, 0.21°/0.44°, 0.33°/0.57°, and 0.31°/0.62°, and the ROM of L3 in the Do-segment FEM were 6.03°/7.31°, 2.52°/3.50°, 4.21°/4.38°, 4.21°/4.42°, 2.09°/2.32°, and 2.07°/2.43°. BPS system had less vertebral displacement, less cage maximum stress, and less spinal ligament tension in Si/Do-segment FEM relative to the LPS system. BPS system had a smaller upper adjacent vertebral ROM, greater intervertebral disc stress in terms of left and right bending as well as left and right rotation compared to the LPS system in the L3-4 of the Do-segment FEM. There was little biomechanical difference between the same fixation system in the Si/Do-segment FEM.ConclusionsOur finite element analysis showed that compared to OLIF + LPS, OLIF + BPS (TINA) is more effective in reducing interbody stress and spinal ligament tension, and it better maintains the stability of the target segment and provides a better fusion environment to resist cage subsidence. However, OLIF + BPS (TINA) may be more likely to cause adjacent segment degeneration than OLIF + LPS.

The retropharyngeal reduction plate for atlantoaxial dislocation: a finite element analysis.

Objective: To investigate the biomechanical properties of the retropharyngeal reduction plate by comparing the traditional posterior pedicle screw-rod fixation by finite element analysis. Methods: Two three-dimensional finite element digital models of the retropharyngeal reduction plate and posterior pedicle screw-rod fixation were constructed and validated based on the DICOM (Digital Imaging and Communications in Medicine) data from C1 to C4. The biomechanical finite element analysis values of two internal fixations were measured and calculated under different conditions, including flexion, extension, bending, and rotation. Results: In addition to the backward extension, there was no significant difference in the maximum von Mises stress between the retropharyngeal reduction plate and posterior pedicle screw fixation under other movement conditions. The retropharyngeal reduction plate has a more uniform distribution under different conditions, such as flexion, extension, bending, and rotation. The stress tolerance of the two internal fixations was basically consistent in flexion, extension, left bending, and right bending. Conclusion: The retropharyngeal reduction plate has a relatively good biomechanical stability without obvious stress concentration under different movement conditions. It shows potential as a fixation option for the treatment of atlantoaxial dislocation.

OLIF联合后路经皮椎弓根螺钉内固定技术与传统TLIF治疗腰椎滑脱症的近期疗效对比

OLIF联合后路经皮椎弓根螺钉内固定技术与传统TLIF治疗腰椎滑脱症的近期疗效对比

CT correlation of spinal canal diameter with pedicle size for safer posterior cervical pedicle screw fixation.

Utilizing computed tomography (CT) studies, we correlated cervical spinal canal diameters (SCDs) with pedicle size between the C3 and C7 levels to more safely perform posterior cervical surgery. We retrospectively analyzed CT studies for 71 patients with cranial or spinal disorders and correlated the cervical SCD with the pedicle outer width (POW) between the C3 and C7 levels. Patients were divided into normal (SCD ≥12 mm at any level, n = 30) and stenosis groups (SCD <12 mm at any level, n = 41). C7 exhibited the largest SCD and POW values, while C3 and C4 exhibited the smallest SCD and POW values. Moderate correlations (r = 0.3, P = 0.002) were observed at the C3 and C4 levels but no significant correlations were observed from the C5 to C7 levels. For SCD values, the normal group demonstrated significantly greater values between the C3 and C7 levels versus the stenosis group. For POW values, only the C4 level differed significantly between the two groups (P = 0.014, Mann-Whitney U-test). Preoperative pedicle size evaluation remains an essential manoeuvre before performing cervical C3-C7 pedicle screw placement. In 71 cervical CT studies, we found no consistent correlation between POW and SCD values, indicating that it is difficult to estimate POW values based on spinal canal size.

Clinical, Radiographic and Fusion Comparison of Oblique Lumbar Interbody Fusion (OLIF) stand-alone and OLIF with posterior pedicle screw fixation in patients with degenerative spondylolisthesis

PurposeTo compare the outcomes and characteristics of oblique lumbar interbody fusion stand-alone (OLIF-SA) and OLIF with posterior pedicle screw fixation (OLIF-PPS) in the treatment of Grade I or Grade II degenerative lumbar spondylolisthesis.Patients and methodsBetween January 2019 and May 2022, 139 patients with degenerative spondylolisthesis were treated with OLIF-SA (n = 85) or OLIF-PPS (n = 54). The clinical and radiographic records were reviewed.ResultsThe clinical and radiographic outcomes were similar in both groups. The operative time and intraoperative blood loss in the OLIF-SA group were lower than those in the OLIF-PPS group (P < 0.05). However, the OLIF-PPS group had significantly better disc height (DH) and postoperative forward spondylolisthesis distance (FSD) improvement at 6 months (P < 0.05). The OLIF-PPS group had a significantly lower cage subsidence value than the OLIF-SA group (P < 0.05). Improvement of the lumbar lordotic angle (LA) and fusion segmental lordotic angle (FSA) in the OLIF-PPS group was significantly better than that in the OLIF-SA group (P < 0.05). In terms of fusion types, the OLIF-SA group tended to undergo fusion from the edge of the vertebral body. Fusion in the OLIF-PPS group began more often in the bone graft area of the central cage of the vertebral body. The fusion speed of the OLIF-SA group was faster than that of the OLIF-PPS group.ConclusionOLIF-SA has the advantages of a short operative time, less intraoperative blood loss, and reduced financial burden, while PPS has incomparable advantages in the reduction of spondylolisthesis, restoration of lumbar physiological curvature, and long-term maintenance of intervertebral DH. In addition, the SA group had a unique vertebral edge fusion method and faster fusion speed.

Biomechanical properties of lumbar vertebral ring apophysis cage under endplate injury: a finite element analysis

ObjectiveThis study aimed to compare the biomechanical properties of lumbar interbody fusion involving two types of cages. The study evaluated the effectiveness of the cage spanning the ring apophysis, regardless of the endplate's integrity.MethodsA finite element model of the normal spine was established and validated in this study. The validated model was then utilized to simulate Lateral Lumbar Interbody Fusion (LLIF) with posterior pedicle screw fixation without posterior osteotomy. Two models of interbody fusion cage were placed at the L4/5 level, and the destruction of the bony endplate caused by curetting the cartilaginous endplate during surgery was simulated. Four models were established, including Model 1 with an intact endplate and long cage spanning the ring apophysis, Model 2 with endplate decortication and long cage spanning the ring apophysis, Model 3 with an intact endplate and short cage, and Model 4 with endplate decortication and short cage. Analyzed were the ROM of the fixed and adjacent segments, screw rod system stress, interface stress between cage and L5 endplate, trabecular bone stress on the upper surface of L5, and intervertebral disc pressure (IDP) of adjacent segments.ResultsThere were no significant differences in ROM and IDP between adjacent segments in each postoperative model. In the short cage model, the range of motion (ROM), contact pressure between the cage and endplate, stress in L5 cancellous bone, and stress in the screw-rod system all exhibited an increase ranging from 0.4% to 79.9%, 252.9% to 526.9%, 27.3% to 133.3%, and 11.4% to 107%, respectively. This trend was further amplified when the endplate was damaged, resulting in a maximum increase of 88.6%, 676.1%, 516.6%, and 109.3%, respectively. Regardless of the integrity of the endplate, the long cage provided greater support strength compared to the short cage.ConclusionsCaution should be exercised during endplate preparation and cage placement to maintain the endplate's integrity. Based on preoperative X-ray evaluation, the selection of a cage that exceeds the width of the pedicle by at least 5 mm (ensuring complete coverage of the vertebral ring) has demonstrated remarkable biomechanical performance in lateral lumbar interbody fusion procedures. By opting for such a cage, we expect a reduced occurrence of complications, including cage subsidence, internal fixation system failure, and rod fracture.

Intraoperative triggered electromyographic monitoring of pedicle screw efficiently reduces the lumbar pedicle breach and re-operative rate-a retrospective analysis based on postoperative computed tomography scan

BackgroundTo investigate whether intraoperative triggered electromyographic (T-EMG) monitoring could effectively reduce the breach rate of pedicle screws and the revision rate.MethodsPatients with posterior pedicle screw fixation from L1-S1 were enrolled between June 2015 and May 2021. The patients in whom T-EMG was utilized were placed in the T-EMG group, and the remaining patients were considered in the non-T-EMG group. Three spine surgeons evaluated the images. The two groups were divided into subgroups based on screw position (lateral/superior and medial/inferior) and breach degree (minor and major). Patient demographics, screw positions, and revision procedures were reviewed.ResultsA total of 713 patients (3403 screws) who underwent postoperative computed tomography (CT) scans were included. Intraobserver and interobserver reliabilities were perfect. The T-EMG and non-T-EMG groups had 374(1723 screws) and 339 (1680 screws) cases, respectively. T-EMG monitoring efficiently reduced the overall screw breach (T-EMG 7.78% vs. non-T-EMG 11.25%, p = 0.001). in the subgroup analysis, the medial/inferior breach rate was higher in the T-EMG group than in the non-T-EMG group (T-EMG 6.27% vs. non-T-EMG 8.93%, p = 0.002); however, no difference was observed between the lateral and superior breaches (p = 0.064). A significant difference was observed between the minor (T-EMG 6.21% vs. non-T-EMG 8.33%, p = 0.001) and major (T-EMG 0.06% vs. non-T-EMG 0.6%, p = 0.001) medial or inferior screw breach rates. Six screws (all in the non-T-EMG group) underwent revision, with a significant difference between the groups (T-EMG 0.0% vs. non-T-EMG 3.17%, p = 0.044).ConclusionsT-EMG is a valuable tool in improving the accuracy of screw placement and reducing the screw revision rate. The screw-nerve root distance is vital in causing symptomatic screw breach.Trial registrationThe study is retrospective registered in China National Medical Research Registration and Archival information system in Nov 17th 2022.