Traditional Pedicle Screw Research Articles

Clinical efficacy of midline lumbar interbody fusion arthrodesis with neuronavigation-guided cortical bone trajectory screws in the treatment of degenerative lumbar spondylolisthesis:a prospective randomized controlled trial

Introduction. Currently, the standard treatment of degenerative spondylolisthesis involves pedicle screw fixation to enhance the success of intervertebral fusion. The traditional pedicle screw techniques require extensive lateral muscle dissection, resulting in significantly increased surgical-related morbidity. To address some of these shortcomings, the Midline Lumbar Interbody Fusion (MIDLIF®) technique has recently been developed. It involves the combination of the cortical bone trajectory screw fixation of the spine with intervertebral cage placement to achieve a solid interbody fusion. So far, the clinical efficacy of the MIDLIF technique in the treatment of low-grade degenerative spondylolisthesis is still unknown. All existing publications are studies with a low level of relevance or scientific evidence. Materials and methods. A prospective randomized controlled trial was conducted between 2017 and 2022. The study analyzed the clinical and radiological effectiveness of the MIDLIF arthrodesis technique compared to the traditional lumbar interbody fusion techniques, used exclusively in the treatment of degenerative lumbar spondylolisthesis. Results. The study enrolled 112 eligible patients with degenerative low-grade spondylolisthesis, randomly assigned into two groups. At 1 year post-operatively, MIDLIF provided a significantly better improvement in postoperative relief of low back pain and radiating pain, as well as a significantly better functional recovery. Additionally, MIDLIF resulted in lower surgical morbidity compared to traditional fusion techniques. Conclusions. The success rate of MIDLIF arthrodesis is similar to that associated with traditional fusion techniques. At the same time, MIDLIF offers all the specific benefits of a minimally invasive approach, such as less postoperative pain, faster functional recovery, less bleeding, and fewer blood transfusions. Thus, MIDLIF might be a good alternative to the traditional intervertebral fusion techniques in the treatment of degenerative low-grade spondylolisthesis.

Research status and existing problems of lumbar pedicle double-trajectory screw technique

Lumbar pedicle double-trajectory screw technique refers to the placement of traditional pedicle screw combined with cortical bone trajectory screw in the same pedicle, which has been proved to provide higher fixation strength in osteoporotic vertebral body fixation, and is also a less invasive surgical choice for revision of adjacent segment disease. At present, related basic research and clinical application exploration of double-trajectory screw technique have been carried out, but there are still many problems that need to be further investigated and clarified. The clinical application and existing problems of double screw technique were discussed in this paper for clinical reference.

Cortical bone trajectory screws in the treatment of lumbar degenerative disc disease in patients with osteoporosis.

Lumbar degenerative disc disease (DDD) in the elderly population remains a global health problem, especially in patients with osteoporosis. Osteoporosis in the elderly can cause failure of internal fixation. Cortical bone trajectory (CBT) is an effective, safe and minimally invasive technique for the treatment of lumbar DDD in patients with osteoporosis. In this review, we analyzed the anatomy, biomechanics, and advantages of the CBT technique in lumbar DDD and revision surgery. Additionally, the clinical trials and case reports, indications, advancements and limitations of this technique were further discussed and reviewed. Finally, we concluded that the CBT technique can be a practical, effective and safe alternative to traditional pedicle screw fixation, especially in DDD patients with osteoporosis.

A Comparison Between Cortical Bone Trajectory Screws And Traditional Pedicle Screws in Patients With Single-Level Lumbar Degenerative Spondylolisthesis: Five-Year Results.

A retrospective observational study. This study investigated the clinical and radiological results of using cortical bone trajectory (CBT) screws versus traditional pedicle (TP) screws in transforaminal lumbar interbody fusion (TLIF) during a five-year follow-up of patients with single-level lumbar degenerative spondylolisthesis. Few studies have compared five-year follow-up outcomes between CBT screws and TP screws in TLIF. We reviewed outcome data of patients with single-level lumbar degenerative spondylolisthesis who underwent TLIF procedures with CBT screws (131 patients) or TP screws (80 patients) between 2011 and 2015. Patient-reported clinical outcome data included Oswestry disability index scores and visual analog scale (VAS) scores for back and leg pain at baseline, six months, and one year, two years, and five years postoperatively. The radiographic fusion rate and prevalence of secondary surgery for adjacent segment disease were also measured. During the follow-up over five years, the CBT group had significantly lower VAS scores for back pain ( P <0.0001, respectively). At two years after surgery, the CBT group had significantly higher VAS scores for leg pain ( P =0.007). At five years postoperatively, no significant differences existed in the VAS score for leg pain or in the Oswestry disability index score between the two groups. Radiographic fusion rates (CBT vs. TP: 95.5% vs. 95.9%; P =0.881) and adverse events during the five years after surgery were not significantly different. At two years postoperatively, the prevalence of secondary surgery to treat adjacent segment disease was significantly different between the two groups (CBT vs . TP: 13.7% vs. 5.0%; P =0.044). Our results suggest that, during a five-year followup, CBT screws for TLIF were an effective treatment compared to TP screws in the setting of single-level lumbar degenerative spondylolisthesis. However, when using CBT screws for TLIF, surgeons should consider the higher rate of secondary procedures to treat symptomatic adjacent segment disease.

Feasibility and improvement of a three-dimensional printed navigation template for modified cortical bone trajectory screw placement in the lumbar spine.

Compared with traditional pedicle screw trajectory, cortical bone trajectory (CBT) increases the contact surface between the screw and cortical bone where the screw is surrounded by dense cortical bone, which does not deform remarkably due to degeneration. We aimed to provide detailed information about the improvement of three-dimensional (3D)-printed navigation templates for modified CBT screw placement in the lumbar spine and evaluate the safety and accuracy thereof. Four human cadaveric lumbar spine specimens were selected. After CT scanning data were reconstructed to 3D models, either the left or right side of each specimen was randomly selected to establish a 3D-navigation template, mutually complemented with the surface anatomical structure of the lateral margin of the lumbar isthmus, vertebral plate, and spinous process. The corresponding 3D centrum was printed according to the CT scanning data, and a navigation template of supporting design was made according to modified cortical bone technique. The same template was used to insert CBT screws into 3D printed and cadaveric specimens. After the screws were inserted, the screw path of the 3D printed specimens was directly observed, and that of the anatomical specimens was scanned by CT, to determine the position and direction of the screws to analyze the success rate of screw placement. Twenty cortical bone screws were placed in each of the 3D printed and anatomical specimens, with excellent rates of screw placement of 100% and 95%, respectively. We report the easy, safe, accurate, and reliable use of a 3D-printed navigation template to carry out screw placement by modified cortical bone technique in the lumbar spine.

Feasibility Analysis of 3D Printing-Assisted Pedicle Screw Correction Surgery for Degenerative Scoliosis.

Objective To explore the feasibility of 3D printing-assisted pedicle screw correction surgery for degenerative scoliosis. Methods From January 1, 2015 to January 31, 2020, patients with degenerative scoliosis who received corrective surgery in our hospital were retrospectively analyzed. Patients were grouped based on the fixation methods. Patients in the control group received traditional pedicle screw internal fixation, while those in the study group received 3D printing-assisted pedicle screw fixation. The therapeutic effects were compared. Results There were 78 cases in the control group and 82 cases in the study group. There were no significant differences in scoliotic Cobb's angle, pelvic incidence-lumbar lordosis (PI-LL), VAS score, JOA score, social function, physical function, role function, or cognitive function between the study group and the control group before the surgery, but there were differences in the above parameters between the two groups after surgery. The incidence of postoperative complications in the study group was also significantly lower in the study group. Conclusion 3D printing-assisted pedicle screw correction surgery provides a strong 3D correction force with reliable effect and fewer complications, and is a good treatment choice for degenerative scoliosis.

Predictors of accurate intrapedicular screw placement in single-level lumbar (L4-5) fusion: robot-assisted pedicle screw, traditional pedicle screw, and cortical bone trajectory screw insertion

BackgroundThe superiorities in proximal facet joint protection of robot-assisted (RA) pedicle screw placement and screw implantation via the cortical bone trajectory (CBT) have rarely been compared. Moreover, findings on the screw accuracy of both techniques are inconsistent. Therefore, we analyzed the screw accuracy and incidence of facet joint violation (FJV) of RA and CBT screw insertion in the same study and compared them with those of conventional pedicle screw (PS) insertion. The possible factors affecting screw accuracy and FJV were also analyzed.MethodsA total of 166 patients with lumbar degenerative diseases requiring posterior L4-5 fusion were retrospectively included and divided into the RA, PS, and CBT groups from March 2019 to December 2021. The grades of intrapedicular accuracy and superior FJV were evaluated according to the Gertzbin–Robbins scale and the Babu scale based on postoperative CT. Univariable and multivariable analyses were conducted to assess the possible risk factors associated with intrapedicular accuracy and superior FJV.ResultsThe rates of optimal screw insertion in the RA, PS, and CBT groups were 87.3%, 81.3%, and 76.5%, respectively. The difference between the RA and CBT groups was statistically significant (P = 0.004). Superior FJVs occurred in 28.2% of screws in RA, 45.0% in PS, and 21.6% in CBT. The RA and CBT groups had fewer superior FJVs than the PS group (P = 0.008 and P < 0.001, respectively), and no significant difference was observed between the RA and CBT groups (P = 0.267). Multivariable analysis revealed that the CBT technique was an independent risk factor for intrapedicular accuracy. Furthermore, older age, the conventional PS technique and a smaller facet angle were independently associated with the incidence of superior FJVs.ConclusionsThe RA and CBT techniques were associated with fewer proximal FJVs than the PS technique. The RA technique showed a higher rate of intrapedicular accuracy than the CBT technique. The CBT technique was independently associated with screw inaccuracy. Older age, conventional PS technique and coronal orientation of the facet join were independent risk factors for superior FJV.

May the midline lumbar interbody fusion (MIDLIF) prevent the early radiographic adjacent segment degeneration? A minimum 3-year follow-up comparative study of MIDLIF in L4/5 with cortical bone trajectory screw versus traditional pedicle screw fixation

Study designRetrospective cohort study.ObjectiveTo compare the early radiographic adjacent segment degeneration (R-ASD) and regional lumbar sagittal alignment after midline lumbar interbody fusion (MIDLIF) with cortical bone trajectory (CBT) screw fixation (CBT-MIDLIF) and posterior lumbar interbody fusion (PLIF) with the traditional pedicle screw fixation (PS-PLIF) during long-term follow-up.MethodsAll patients who underwent CBT-MIDLIF or PS-PLIF were identified by a retrospective consecutive case review. Radiographic parameters in cephalad adjacent segment (L3/4), including intervertebral space height (ISH), foraminal height (FH), foraminal width (FW), range of motion were assessed. Lumbar lordosis (LL), sacral slope (SS), L4–L5 Cobb angle, Cobb angle of the intervertebral space at L4–L5, and height of the anterior and posterior edges of the intervertebral space at L4–L5, were measured and compared on preoperative, postoperative, and 3-year follow-up radiographic evaluation.ResultsSeventy-four patients underwent CBT-MIDLIF (CBT-MIDLIF group) and 114 patients underwent conventional PS-PLIF (PS-PLIF group). ISH, FH and FW were significantly smaller at 6-month follow-up than before operation with PS-PLIF (p < 0.001) but showed no significant changes with CBT-MIDLIF (p > 0.05). At the last follow-up, the changes in cephalad R-ASD parameters were more remarkable after PS-PLIF than after CBT-MIDLIF (p < 0.01). LL and SS were significant larger at the last follow-up than before operation in both groups (p < 0.001). Regarding long-term outcomes, the symptoms caused by degenerative spinal disorders significantly improved in both groups (p < 0.01).ConclusionCBT-MIDLIF had less radiographic degeneration in the adjacent segment than PS-PLIF at 3-year follow-up. The lumbar sagittal alignment could be improved significantly and the surgical outcomes were satisfactory after either CBT-MIDLIF or PS-PLIF.

Comparative Outcomes of Cortical Bone Trajectory Screw Fixation and Traditional Pedicle Screws in Lumbar Fusion: A Meta-Analysis

Pedicular screws (PS) often are used in lumbar fusion. Cortical bone trajectory (CBT) is a novel technology in lumbar fusion with less evidence of clinical outcomes. Therefore, we conducted a meta-analysis to compare the efficacy and safety between CBT screw fixation and traditional PS in lumbar fusion surgery. Multiple databases were searched for the articles that compared CBT and traditional PS in lumbar fusion surgeries. Meta-analysis was conducted by RevMan 5.3 software. The following indicators were abstracted: visual analog scale (VAS) scores for back and leg pain, Oswestry Disability Index (ODI), Japanese Orthopaedic Association (JOA) score, surgical duration, complications, and blood loss. The quality of the articles was assessed by the Newcastle-Ottawa Scale or Cochrane Handbook. In total, 25 studies were included, involving a total of 1735 patients. There was no difference in preoperative VAS scores, JOA, ODI, postoperative VAS scores, and fusion rates. In addition, postoperative JOA (mean difference [MD]= 0.78, P= 0.02), ODI (MD= -2.09, P=0.03), surgical duration (MD= -26.90, P= 0.02), complications (MD= 0.70, P= 0.03), and blood loss (MD= -85.27, P= 0.0009) showed greater improvement trends in the CBT group than the PS group, with significant difference. CBT reduced the rate of complications, surgical duration, blood loss, postoperative ODI, and JOA scores. The CBT technique, with better postoperative outcomes, achieved similar fusion rates compared with the PS technique.

What's New in Spine Surgery.

What's New in Spine Surgery.

Finite element analysis of human lumbar vertebrae in internal fixation system model with different bone density trajectories.

To evaluate the biomechanics effect of modified cortical bone screw technique (MCBT) with other traditional internal fixation systems on lumbar osteoporotic wet specimen. Four different finite element models were established using CT data: (1) lumbar osteoporosis model without internal fixation system; (2) traditional pedicle screw technology (TT) model; (3) traditional cortical bone screw technology (CBT) model; (4) MCBT model. The changes of global displacement, intervertebral disc displacement of all models and internal fixation system Von Mises stress among the three models were compared under the same physiological load. Compared with the other three models, the total displacement of the modified CBT screw model was the smallest, with the maximum displacement of 0.216 mm; The intervertebral disc displacement of the modified CBT screw model was the smallest, with the maximum displacement of 0.149 mm; the internal fixation system Von Mises stress of the modified CBT screw technique model was the largest compared with the other three models, The maximum Von Mises stress is 232.73 MPa. Compared to traditional pedicle screw and traditional CBT, MCBT has better mechanical stability, and it is of certain clinical application value.

Biomechanical Investigation of the Posterior Pedicle Screw Fixation System at Level L4-L5 Lumbar Segment with Traditional and Cortical Trajectories: A Finite Element Study.

There is no detailed biomechanical research about the hybrid CBT-TT (CBT screws at cranial level and TT screws at caudal level) and TT-CBT (TT screws at cranial level and CBT screws at caudal level) techniques with finite element (FE) method. Therefore, the purpose of this study was to evaluate and provide specific biomechanical data of the hybrid lumbar posterior fixation system and compare with traditional pedicle screw and cortical screw trajectories without fusion, in FE method. Specimens were from the anatomy laboratory of Xinjiang Medical University. Four FE models of the L4-L5 lumbar spine segment were generated. For each of these, four implanted models with the following instruments were created: bilateral traditional trajectory screw fixation (TT-TT), bilateral cortical bone trajectory screw fixation (CBT-CBT), hybrid CBT-TT fixation, and hybrid TT-CBT fixation. A 400 N compressive load with 7.5 Nm moments was applied so as to simulate flexion, extension, left lateral bending, right lateral bending, left rotation, and right rotation, respectively. The range of motion (ROM) of the L4-L5 segment and the posterior fixation, the von Mises stress of the intervertebral disc, and the posterior fixation in four implanted models were compared. CBT-TT displayed a lower ROM of the fixation segment (3.82 ± 0.633°) compared to TT-TT (4.78 ± 0.306°) and CBT-CBT (4.23 ± 0.396°). In addition, CBT-TT showed a lower ROM of the posterior fixation (0.595 ± 0.108°) compared to TT-TT (0.795 ± 0.103°) and CBT-CBT (0.758 ± 0.052°). The intervertebral disc stress of CBT-TT (4.435 ± 0.604 MPa) was lower than TT-TT (7.592 ± 0.387 MPa) and CBT-CBT (6.605 ± 0.600 MPa). CBT-TT (20.228 ± 3.044 MPa) and TT-CBT (12.548 ± 2.914 MPa) displayed a lower peak von Mises stress of the posterior fixation compared to TT-TT (25.480 ± 3.737 MPa). The hybrid CBT-TT and TT-CBT techniques offered superior fixation strength compared to the CBT-CBT and TT-TT techniques.

Cortical Trajectory Fixation Versus Traditional Pedicle-Screw Fixation in the Treatment of Lumbar Degenerative Patients with Osteoporosis: A Prospective Randomized Controlled Trial.

Study DesignThis was a prospective randomized controlled trial study.ObjectiveTo elucidate clinical and radiographic outcomes and complications of cortical bone trajectory (CBT)-screw fixation in patients with osteoporosis at 24-month follow-up and to compare the results with those after transforaminal lumbar interbody fusion (TLIF) using traditional pedicle screw (PS) fixation.MethodsWe enrolled 124 patients and randomly assigned them to two groups (each group had 62 participants). The primary outcome was fusion rate. Secondary outcomes were VAS, Oswestry Disability Index (ODI), and Japanese Orthopaedic Association (JOA) scores, operation duration, incision length, estimated blood loss, drainage volume, radiological outcomes, and complications.ResultsAt the 6- and 12-month follow-up points, similar fusion rates were observed based on CT scans in both groups (P=0.583 and 0.583). CBT provided significantly better short-term functional status at 3 months postoperation on ODI and JOA scores (P=0.012 and 0) and similar improvements in pain intensity and functional status at other follow-up points. In addition, CBT resulted in significantly better surgical characteristics. Notably, CBT fixation led to lower incidence of screw loosening (P=0.006).ConclusionCBT-screw fixation for single-level lumbar fusion in patients with osteoporosis provided improvement in clinical symptoms comparable to that of TLIF using PS fixation. Significantly better lumbar stability was found in the CBT group. We suggest that CBT-screw fixation is a reasonable and superior alternative to PS in TLIF in osteoporosis.Trial Registration NumberChiCTR1900022658.Date of RegistrationApril 20, 2019.

Sequential endoscopic and robot-assisted surgical solutions for a rare fungal spondylodiscitis, secondary lumbar spinal stenosis, and subsequent discal pseudocyst causing acute cauda equina syndrome: a case report

BackgroundFungal spondylodiscitis is a rare infectious disease. The secondary lumbar spinal stenosis and postoperative discal pseudocyst were even rarer. The surgical interventions were disputed, yet endoscopic and robot-assisted techniques may be helpful under different circumstances.Case presentationA 62-year-old female was diagnosed as infectious spondylodiscitis at the L4/5 level and a posterolateral endoscopic debridement was performed after invalid conservative therapy. Causative organism culture revealed a rare fungus, Candidatropicalis. A secondary spinal stenosis with refractory radiculopathy occurred almost 3 years after the first surgery and a successful endoscopic surgery was implemented aiming to decompress the nerve in a minimally invasive way. However, 2 months later, the patient manifested severe acute cauda equina syndrome and radiological examinations suggested a rare postoperative discal pseudocyst. A laminectomy followed by a pseudocystectomy was applied to achieve thorough decompression. An innovative double trajectory system (simultaneous traditional pedicle screw and cortical bone trajectory screw) accompanied by posterolateral fusion was designed and executed by the professional robot-assisted system.ConclusionEndoscopic and robot-assisted techniques may provide alternative solutions for fungal spondylodiscitis and accompanied sequelae.

Application expansion and related problems of lumbar cortical bone trajectory screw technique

At the beginning of clinical application, CBT technique was mainly used for lumbar degenerative diseases in Elderly Patients, and single or double segments of lower lumbar vertebrae accounted for the majority. With the technical proficiency and equipment improvement, the types of diseases continue to expand, and CBT technique can be used in conjunction with traditional pedicle screw technology, which plays an important role in the revision of adjacent segment disease and fixation in lumbar vertebrae of patients with severe osteoporosis. However, CBT technology has not been widely used, and there are still related problems that need to be clarified and further studied.

Use of L5-S1 transdiscal screws in the treatment of isthmic spondylolisthesis: a technical note.

Surgical treatment of L5-S1 isthmic spondylolisthesis consists of a combination of decompression and fusion. One previously discussed mode of fusion is via transdiscal screws. Biomechanical studies of transdiscal screws have demonstrated greater rigidity than traditional pedicle screw fixation, which theoretically translates to a higher fusion rate. Furthermore, when compared to pedicle screw fixation, transdiscal screw fixation also demonstrates improved functional and radiographic outcomes. However, transdiscal screw placement can be technically difficult. At this time, a detailed surgical technique has yet to be reported in the literature. Our surgical technique for transdiscal screw placement using intraoperative C-arm at L5-S1 is described. We include considerations for preoperative planning including necessary imaging and appropriate patient selection. We also discuss intraoperative concerns such as setup, surgical approach, proper screw trajectory, and our method for achieving indirect decompression. The results of thirteen consecutive patients treated with transdiscal screw fixation are described. One patient had subcutaneous seroma requiring reoperation (7.7%), three patients had implant failure (23.1%), and one patient had nonunion (7.7%). Our results suggest that transdiscal screw fixation is a safe and acceptable alternative for stabilization and indirect decompression of L5-S1 isthmic spondylolisthesis. Recent innovation in intraoperative navigation and robotic surgery may lessen the technical difficulty of transdiscal screw placement and make it even more effective.

Effect of percutaneous minimally invasive pedicle screw internal fixation in the treatment of thoracolumbar vertebral fractures and its impact on quality of life.

ABSTRACTObjectives:To investigate and analyze the effect of percutaneous minimally invasive pedicle screw internal fixation in the treatment of thoracolumbar vertebral fractures and its impact on quality of life.Methods:Fifty patients with thoracolumbar vertebral fracture admitted to our hospital from January 2015 to December 2018 were selected and divided into two groups according to different treatment regimens. The observation group was treated with minimally invasive percutaneous pedicle screw internal fixation, while the control group was treated with traditional posterior approach open pedicle screw internal fixation. The surgery time, incision length, intraoperative blood loss, postoperative drainage, hospitalization time, ambulation time, fracture healing time and postoperative VAS scores were compared between the two groups. In addition, the cobb angle, the sagittal plane index, and the anterior vertebral height were compared between the two groups before and after surgery, as were the Oswestry Disability Index (ODI) at 1d, 3 months, and 6 months postoperatively.Results:The surgery time, incision length, postoperative pain level, postoperative drainage and intraoperative blood loss of the observation group were less than those of the control group (P<0.05). The postoperative Cobb angle of the two groups decreased, the sagittal plane index as well as the anterior vertebral height increased (P<0.05). The Oswestry index of the observation group was better than that of the control group at one day and three months postoperatively, with a statistical significance between the two groups (P<0.05). The complication rate of the observation group was significantly lower than that of the control group (P<0.05).Conclusion:Percutaneous minimally invasive pedicle screw internal fixation is safer than the traditional open pedicle screw internal fixation, and it is more worthy of clinical promotion.

Posterior spinal instrumentation and decompression with or without cross-link?

BackgroundPosterior lumbar instrumentation requires sufficient primary stiffness to ensure bony fusion and to avoid pseudarthrosis, screw loosening, or implant failure. To enhance primary construct stiffness, transverse cross-link (CL) connectors attached to the vertical rods can be used. Their effect on the stability of a spinal instrumentation with simultaneous decompression is yet not clear. This study aimed to evaluate the impact of CL augmentation on single-level lumbar instrumentation stiffness after gradual decompression procedures. MethodsSeventeen vertebral segments (6 L1/2, 6 L3/4, 5 L5/S1) of 12 fresh-frozen human cadavers were instrumented with a transpedicular screw–rod construct following the traditional pedicle screw trajectory. Range of motion (ROM) of the segments was sequentially recorded before and after four procedures: (A) instrumented before decompression, (B) instrumented after unilateral laminotomy, (C) instrumented after midline bilateral laminotomy, and (D) instrumented after unilateral facetectomy (with transforaminal lumbar interbody fusion [TLIF]). Each test was performed with and without CL augmentation. The motion between the cranial and caudal vertebrae was evaluated in all six major loading directions: flexion/extension (FE), lateral bending (LB), lateral shear (LS), anterior shear (AS), axial rotation (AR), and axial compression/distraction (AC). ResultsROM was significantly reduced with CL augmentation in AR by Δ0.03–0.18° (7–12%) with a significantly higher ROM reduction after more extensive decompression. Furthermore, slight reductions in FE and LB were observed; these reached statistical significance for FE after facetectomy and TLIF insertion only (Δ0.15; 3%). The instrumentation levels did not reveal any subgroup differences. ConclusionCL augmentation reduces AR-ROM by 7–12% in single-level instrumentation of the lumbar spine, with the effect increasing along with the extensiveness of the decompression technique. In light of the discrete absolute changes, CL augmentation may be warranted for highly unstable vertebral segments rather than for standard single-level posterior spinal fusion and decompression.

Biomechanical Evaluation of Cortical Bone Trajectory Fixation with Traditional Pedicle Screw in the Lumbar Spine: A Finite Element Study

Cortical bone trajectory (CBT) is increasingly used in spinal surgery. Although there are many biomechanical studies, the biomechanical effect of CBT in combination with traditional pedicle screws is not detailed. Therefore, the purpose of this study was to investigate the effects of the traditional pedicle screw and CBT screw implantation on the lumbar spine using finite element methods. Based on the combination of the traditional pedicle screw and the CBT system implanted into the lumbar spine, four finite element spinal lumbar models were established. The models were given four different load conditions (flexion, extension, lateral bending, and axial rotation), and the deformation and stress distribution on the finite element model were observed. The results show that there was no significant difference in the structural stability of the lumbar spine model between the traditional pedicle screw system and the CBT system. In addition, CBT may reduce stress on the endplate. Different movements performed by the model may have significant biomechanical effects on the spine and screw system. Clinical spinal surgeons may also consider using the CBT system in revision spinal surgery, which may contribute to smaller wounds.

Feasibility of cortical bone trajectory screws for bridging fixation in revision surgery for lumbar adjacent segment degeneration.

Background:To investigate the feasibility of using cortical bone trajectory (CBT) screws for bridging fixation in revision surgery for lumbar adjacent segment degeneration and to provide a reference for clinical practice.Methods:Computed tomography scans of the lumbar spines of 36 patients in our hospital were used. Sixteen males and 20 females with an average age of 65.5 ± 10.5 years (range: 46 to 83 years) were included. Three-dimensional reconstruction was performed using computer software. Screws with appropriate sizes were selected for the L1 to L5 vertebral segments, and traditional pedicle screws were placed using the standard method. After completing screw placement, simulated placement of CBT screws was performed separately. No overlap occurred between the two screws in the process of CBT screw placement, and the placement point and direction were adjusted until screw placement completion. After all screw placement simulations were complete, according to the contact area of the cortical bone of the screw trajectory and the screw puncture position and distance through the trajectory, the screw placement results were categorized as excellent, good, general, and failure. Excellent and good ratings were considered successful, while a general rating was regarded as acceptable. Then, the success rate and acceptable rate of each segment of the lumbar spine were calculated.Results:Three hundred and sixty screw placement simulations were performed in lumbar pedicles, and 72 CBT screws were implanted in each vertebral body of the lumbar spine. The success rates in the L1 to L5 segments were 73.6%, 80.6%, 83.3%, 88.9%, and 77.8%, respectively, and the acceptable rates were 91.7%, 97.2%, 97.2%, 100%, and 91.7%, respectively. The overall success rate and acceptable rate of CBT screw placement in the lumbar spine were 80.8% and 95.6%, respectively.Conclusion:CBT screws are feasible for bridging fixation in lumbar adjacent segment degeneration revision surgery, and the accuracy of screw placement in different lumbar vertebrae varies.