Biomechanical evaluation of the hybrid pedicle screw-cortical bone trajectory technique in transforaminal lumbar interbody fusion to adjacent segment degeneration-finite element analysis.

BACKGROUND: Transforaminal lumbar interbody fusion is an effective surgical treatment of intervertebral disk herniation. However, its clinical efficacy for adjacent segment disk degeneration (ASDD) after hybrid bilateral pedicle screw - bilateral cortical screw (pedicle screw at L4 and cortical bone trajectory screw at L5) and hybrid bilateral cortical screw - bilateral pedicle screw (bilateral cortical screw at L4 and bilateral pedicle screw at L5) remains undiscovered. Therefore, the aim of this study is to evaluate the effect of the hybrid bilateral pedicle screw - bilateral cortical screw and hybrid bilateral cortical screw - bilateral pedicle screw on the adjacent segment via a 3-dimensional (3D) finite element (FE) analysis. METHODS: Four human cadaveric lumbar spine specimens were provided by the anatomy teaching and research department of Xinjiang Medical University. Four finite element models of L1-S1 lumbar spine segment were generated. For each of these, four lumbar transforaminal lumbar interbody fusion models at L4-L5 segment with the following instruments were created: hybrid bilateral pedicle screw - bilateral cortical screw, bilateral cortical screw - bilateral cortical screw (bilateral cortical screw at both L4 and L5 segments), bilateral pedicle screw - bilateral pedicle screw (bilateral pedicle screw at both L4 and L5 segments), and hybrid bilateral cortical screw - bilateral pedicle screw. A 400-N compressive load with 7.5 Nm moments was applied for the simulation of flexion, extension, lateral bending, and rotation. The range of motion of L3-L4 and L5-S1 segments and von Mises stress of the intervertebral disc at the adjacent segment were compared. RESULTS: Hybrid bilateral pedicle screw - bilateral cortical screw has the lowest range of motion at L3-L4 segment in flexion, extension, and lateral bending, and the highest disc stress in all motions, while the range of motion at L5-S1 segment and disc stress was lower than bilateral pedicle screw - bilateral pedicle screw in flexion, extension, and lateral bending, and higher than bilateral cortical screw - bilateral cortical screw in all motions. The range of motion of hybrid bilateral cortical screw - bilateral pedicle screw at L3-L4 segment was lower than bilateral pedicle screw - bilateral pedicle screw and higher than bilateral cortical screw - bilateral cortical screw in flexion, extension, and lateral bending, and the range of motion at L5-S1 segment was higher than bilateral pedicle screw - bilateral pedicle screw in flexion, lateral bending, and axial rotation. The disc stress at L3-L4 segment was lowest and more dispersed in all motions, and the disc stress at L5-S1 segment was higher than bilateral pedicle screw - bilateral pedicle screw in lateral bending and axial rotation, but more dispersed. CONCLUSION: Hybrid bilateral cortical screw - bilateral pedicle screw decreases the impact on adjacent segments after spinal fusion, reduces the iatrogenic injury to the paravertebral tissues, and provides throughout decompression of the lateral recess.

The effect of the cortical bone trajectory screw fixation and traditional pedicle screw fixation on surgical site wound infection in posterior lumbar fusion wound: A meta-analysis.

A meta-analysis investigation was performed to measure the influence of cortical bone trajectory screw fixation (CBTSF) and traditional pedicle screw fixation (TPSF) on surgical site wound infection (SSWI) in posterior lumbar fusion (PLF). A comprehensive literature inspection till February 2023 was applied and 1657 interrelated investigations were reviewed. The 13 chosen investigations enclosed 1195 individuals with PLF in the chosen investigations' starting point, 578 of them were using CBTSF, and 617 were using TPSF. Odds ratio (OR) in addition to 95% confidence intervals (CIs) were utilised to compute the value of the effect of the CBTSF and TPSF on SSWI in PLF by the dichotomous approaches and a fixed or random model. No significant difference was found between individuals using CBTSF and TPSF in SSWI (OR, 0.68; 95% CI, 0.35-1.33, P = .26), superficial SSWI (OR, 0.62; 95% CI, 0.22-1.79, P = .38), and deep SSWI (OR, 0.30; 95% CI, 0.06-1.50, P = .14) in PLF. No significant difference was found between individuals using CBTSF and TPSF in SSWI, superficial SSWI, and deep SSWI in PLF. However, care must be exercised when dealing with its values because of the small sample sizes of several chosen investigations for this meta-analysis and the low number of selected investigations for a certain type of SSWI.

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 DESIGN: Retrospective cohort study. OBJECTIVE: To 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. METHODS: All 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. RESULTS: Seventy-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). CONCLUSION: CBT-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.

Double-trajectory lumbar screw placement guided by a set of 3D-printed surgical guide templates: a cadaver study.

BACKGROUND: To improve the strength of posterior spine fixation in patients with osteoporosis, some scholars have proposed a method of simultaneously inserting traditional pedicle screws and cortical bone trajectory screws into the pedicle. However, due to the difficulty of the operation and few clinical applications, the safety and accuracy of this method are still unclear. The purpose of this study was to investigate the safety and accuracy of double-trajectory lumbar screw placement guided by surgical guide templates. METHODS: Six wet lumbar specimens were selected for computed tomography (CT) scanning, a three-dimensional (3D) model of the lumbar spine was established using computer software, and surgical guide templates for double-trajectory [traditional pedicle trajectory (TPT) and cortical bone trajectory (CBT)] lumbar screw placement at various segments of the lumbar spine were designed and printed using a 3D printer. Screw placement was guided only by the surgical guide template, with no fluoroscopy. Postoperative CT examination was performed to determine whether the screw penetrated the screw path and the location and depth of penetration of the cortex. The preoperative and postoperative sagittal and axial angles of CBT screws or TPT screws were also measured and compared. RESULTS: Four screws were placed in each vertebral body of six lumbar specimens for a total of 120 screws. Screw grades: 99 screws as grade 0, 15 as grade 1, six as grade 2, and zero as grade 3. Thus, grade 0 accounted for 82.5% of the screws. No significant differences in the preoperative and postoperative angles of the screws were found (P > 0.05). CONCLUSIONS: 3D-printed surgical guide templates for double-trajectory screw placement can reduce the difficulty of surgery and the use of intraoperative fluoroscopy. Using such templates is a safe, feasible, and accurate screw placement method.

[Effect of posterior lumbar fusion on the degeneration of adjacent segments using cortical bone trajectory screw fixation].

Objective: To compare the degenerative changes of adjacent segments after posterior lumbar fusion surgery using cortical bone trajectory (CBT) screws and pedicle screws (PS) in lumbar spinal degenerative disease. Methods: According to certain inclusion and exclusion criteria, prospective non-randomized study on cases of the single-segment lumbar spinal fusion surgery using cortical bone trajectory screws fixation and pedicle screws fixation in Beijing Chao-Yang Hospital from January 2015 to February 2016 was performed. The intervertebral space height (ISH), foramen height (FH), foramen width (FW), cephalad adjacent segment (CAS) and intervertebral disc degeneration grades at MRI scans were measured before surgery and during follow-up. Clinical symptoms were evaluated by Oswestry Dysfunction Index (ODI) score and pain visual analogue scale (VAS) before and during the follow-up. Radiologic adjacent segment degeneration (R-ASD) and symptomatic adjacent segment disease (S-ASD) patients were diagnosed during the follow-up. Paired sample t test was performed when data were compared before surgery and during follow-up. Results: A total of 69 patients were included in the study, 33 in the CBT group (male/female, 15/18), with an average age of (65±11) years, and 36 in the PS group (male/female, 17/19), with an average age of (64±10) years. The follow-up time was no less than 36 months. At the last follow-up, the ISH of the adjacent segments in the CBT group were not statistically different from that before surgery; the ISH of the adjacent segments in the PS group were significantly reduced compared with that before surgery (t=6.78, P<0.05). The loss of ISH, FH, and FW in the adjacent segments in the CBT group were smaller than those in the PS group, and the differences were statistically significant. During follow-up, 4 cases (12.1%) of R-ASD and no S-ASD were found in the CBT group, while 12 cases (33.3%) of R-ASD appeared in the PS group, which was significantly higher than that in the CBT group (χ(2)=4.35, P=0.04). According to MRI, the adjacent discs of PS group had significantly more severe degeneration at the last follow-up than the CBT group (Z=-2.14, P=0.03). Conclusions: Compared with the PS fixation fusion, the CBT screw fixation can effectively reduce the occurrence of adjacent segment degeneration.

The Influence of Titanium-coated Poryetheretherketone Cages in Fusion Status after Posterior Lumbar Interbody Fusion with Cortical Bone Trajectory Screw Fixation.

OBJECTIVE: Posterior lumbar interbody fusion (PLIF) with cortical bone trajectory (CBT) screw fixation (CBT-PLIF) shows potential for reducing adjacent segmental disease. Previously, our investigations revealed a relatively lower fusion rate with the use of carbon fiber-reinforced polyetheretherketone (CP) cages in CBT-PLIF compared with traditional pedicle screw fixation (PS-PLIF) using CP cages. This study aims to evaluate whether the implementation of titanium-coated polyetheretherketone (TP) cages can enhance fusion outcomes in CBT-PLIF. METHODS: A retrospective analysis was conducted on 68 consecutive patients who underwent CBT-PLIF with TP cages (TP group) and 89 patients who underwent CBT-PLIF with CP cages (CP group). Fusion status was assessed using computed tomography at 1 year postoperatively and dynamic plain radiographs at 2 years postoperatively. RESULTS: No statistically significant differences in fusion rates were observed at 1 and 2 years postoperatively between the TP group (86.8% and 89.7%, respectively) and the CP group (77.5% and 88.8%, respectively). Notably, the CP group exhibited a significant improvement in fusion rate from 1 to 2 years postoperatively (P = 0.002), while no significant improvement was observed in the TP group. CONCLUSIONS: Examination of temporal changes in fusion rates reveals that only the TP group achieved a peak fusion rate 1 year postoperatively. This implies that TP cages may enhance the fusion process even after CBT-PLIF. Nevertheless, the definitive efficacy of TP cages for CBT-PLIF remains uncertain in the context of overall fusion rates.

Efficacy and Safety of Cortical Bone Trajectory Screws versus Pedicle Screws in Lumbar Fusion: A Systematic Review and Meta-Analysis.

OBJECTIVE: A systematic review and meta-analysis was conducted to compare the efficacy and safety of cortical bone trajectory (CBT) screws and traditional pedicle screws in lumbar fusion. METHODS: Randomized controlled studies and cohort studies on CBT versus pedicle screws in lumbar fusion were searched in China Biology Medicine, China National Knowledge Infrastructure, Wanfang, VIP Database for Chinese Technical and Science Periodicals, PubMed, Cochrane Library, and Web of Science databases. The search period spanned from the establishment of the databases to December 2023. The Cochrane bias risk assessment tool and Newcastle-Ottawa scale were applied to assess the quality of the literature included. Clinical and imaging data as well as surgical outcomes, recovery, and postoperative complications were extracted from the relevant literature. RESULTS: A total of 6 randomized controlled trials and 26 cohort studies were included after screening by inclusion and exclusion criteria with a total of 2478 patients. The meta-analysis demonstrated significant discrepancies between the CBT and TPS groups in Japanese Orthopaedic Association score at 3 and 6 months and final follow-up. Moreover, the TPS group exhibited a higher Oswestry disability index at final follow-up, a greater VAS for low back pain at both 1 week and final follow-up, as well as a higher VAS for leg pain at 1 month. Differences were also noted in surgical and recovery outcomes. However, there was no significant difference between the 2 groups in postoperative complications. CONCLUSIONS: CBT and TPS have analogous safety profiles when applied to lumbar fusion, but the clinical efficacy of CBT is superior to that of TPS to some extent, and the procedure is less invasive with faster recovery.

Finite Element Analysis of Cortical Bone Trajectory Screw Resistance to Pullout During Exposure to Different Cortical Layers Based on AbaqusCEA Software.

Objective: To investigate the maximum anti-pullout force and stress distribution of cortical bone trajectory (CBT) screws during screw pullout after contacting different cortical bone layers by finite element analysis (FEA) based on Abaqus software, and to provide evidence for increasing screw holding force during CBT screw implantation in clinical practice. Methods: Based on the plain CT data of lumbar spine of a healthy male volunteer who visited the Fourth People's Hospital of Guiyang in June 2022, and the standard screw parameters according to cortical bone trajectory screws. A three-dimensional model of L4 vertebral body and CBT screw was established. The diagnostic criteria of osteoporosis by quantitative CT of lumbar spine in China were set as 120 mg/cm3 low bone mass model. According to the number of contact layers between screws and cortical bone, the models were divided into group A: CBT screws produced one layer of cortical bone contact with the vertebral body (screw implantation point); group B: CBT pedicle screws produced two layers of cortical bone contact with the vertebral body (screw implantation point + pedicle inner edge); group C: CBT pedicle screws produced three layers of cortical bone contact with the vertebral body (screw implantation point + pedicle inner edge + outer edge of the vertebral body); group D: CBT pedicle screws produced four layers of cortical bone contact with the vertebral body (screw implantation point + pedicle upper wall + pedicle lateral wall + upper edge of the vertebral body); group E: CBT pedicle screws produced five layers of cortical bone contact with the vertebral body (screw implantation point + pedicle posteromedial medial wall + anterolateral wall of the pedicle + upper edge of the vertebral body + outer edge of the vertebral body). According to the reference, after the material assignment was completed, the axial pullout force experiment of screws was simulated on Abaqus CEA engineering software for five groups of finite element models established to observe the maximum axial pullout force of each group of models and the stress distribution of screws and vertebral bodies. For the comparative analysis between each group of models corresponding to the measured data, one-way analysis of variance was used. Results: The stress of cancellous bone failure in finite element model of group E was (8.6 ± 0.9), (8.4 ± 0.9), (8.1 ± 0.9), (8.3 ± 0.8), and (8.8 ± 0.7) MPa, respectively, and there was no significant difference between any group (P > 0.05); the maximum principal stress in the tail of screw was (195.1 ± 35.8), (290.9 ± 32.1), (317.3 ± 44.5), (396.3 ± 51.2), and (526.5 ± 53.1) MPa, respectively, and the stress in cortical bone destruction was (40.6 ± 3.5), (52.6 ± 4.2), (89.4 ± 4.9), (109.0 ± 8.3), and (129.4 ± 6.4) MPa, respectively, and there was significant difference between any group (P < 0.05); the maximum axial pullout force in group A-E was (1890.5 ± 45.0), (1913.4 ± 53.8), (2371.0 ± 108.3), (237.2 ± 43.0), and (119.5 ± 43.0), respectively. The increases were 2%, 16%, 5%, and 7%. There were significant differences between each group and group E (P < 0.05). Conclusion: Axial pullout force increases as the number of contact layers between CBT screws and cortical bone increases. The axial pullout force increases most when the cortical trajectory screw contacts the vertebral body with three layers of cortical bone, and reaches the maximum value when the number of contact layers reaches five layers, regardless of the screw tail stress and the maximum axial pullout force, so it is clinically desirable to make the screw contact more than three layers of cortical bone to obtain higher stability during screw implantation, improve screw stability, and increase the surgical fusion rate.

Multitrack and multianchor point screw technique combined with the Wiltse approach for lesion debridement for lumbar tuberculosis.

BACKGROUND: The incidence of lumbar tuberculosis is high worldwide, and effective treatment is a continuing problem. AIM: To study the safety and efficacy of the multitrack and multianchor point screw technique combined with the contralateral Wiltse approach for lesion debridement to treat lumbar tuberculosis. METHODS: The C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR), visual analogue scale (VAS) score, oswestry disability index (ODI) and American Spinal Injury Association (ASIA) grade were recorded and analysed pre- and postoperatively. RESULTS: The CRP level and ESR returned to normal, and the VAS score and ODI were decreased at 3 mo postoperatively, with significant differences compared with the preoperative values (P < 0.01). Neurological dysfunction was relieved, and the ASIA grade increased, with no adverse events. CONCLUSION: The multitrack, multianchor point screw fixation technique combined with the contralateral Wiltse approach for debridement is an effective and safe method for the treatment of lumbar tuberculosis.

The Fusion Rate of Cortical Bone Trajectory Screw Fixation and Pedicle Screw Fixations in L4-5 Interbody Fusion: A Retrospective Cohort Study.

OBJECTIVE: Although cortical bone trajectory (CBT) screw fixation has been used for several years, the number of studies on its fusion effects is limited. Furthermore, several studies report conflicting outcomes. We aimed to compare the fusion rates and clinical efficacy of CBT screw fixation and pedicle screw (PS) fixation for L4-L5 interbody fusion. METHODS: This study was a retrospective cohort control study. Patients with lumbar degenerative disease who underwent L4-L5 oblique lumbar interbody fusion (OLIF) or posterior decompression using CBT screws between February 2016 and February 2019 were included. Patients in whom PS was used were matched for age, sex, height, weight, and BMI. Record the operation time, blood loss. All enrolled patients underwent lumbar CT imaging at one-year follow-up to evaluate the fusion rate. At the two-year follow-up the visual analogue scale (VAS), Oswestry disability index (ODI), and Japanese Orthopaedic Association scores (JOA) were used to identify symptom improvement. Independent t-test was used for the comparison, and score data were analyzed using the χ2 and exact probability tests. RESULTS: A total of 144 patients with were included. All patients were followed-up postoperatively for 25-36 months (average 32.42 ± 10.55 months). Twenty-eight patients underwent OLIF and CBT screw fixation, 36 underwent OLIF and PS fixation, 32 underwent posterior decompression and CBT screw fixation, and 48 underwent posterior decompression and PS fixation. The fusion rates following CBT screw and PS fixations in OLIF were 92.86% (26/28) and 91.67% (33/36), respectively (P = 1). The fusion rates following CBT screw and PS fixations in posterior decompression were 93.75% (30/32) and 93.75% (45/48), respectively (P > 0.05). Regardless of OLIF or posterior decompression, there were no significant differences in the VAS, ODI, and JOA scores between patients treated with CBT and PS (P > 0.05). CONCLUSION: CBT screw fixation can achieve a satisfactory interbody fusion rate with a clinical efficacy similar to that of PS in patients with lumbar degenerative disease, regardless of whether OLIF or posterior decompression was performed.

Biomechanical Analysis of Double-Level Oblique Lumbar Fusion with Different Types of Fixation: A Finite Element-Based Study.

OBJECTIVE: One well-liked less invasive procedure is oblique lumbar interbody fusion (OLIF). The biomechanical characteristics of double-level oblique lumbar interbody fusion in conjunction with various internal fixations are poorly understood. The purpose of this study was to clarify the biomechanical characteristics of double-level oblique lumbar interbody fusion for osteoporosis spines using various internal fixation techniques. METHODS: Based on CT scans of healthy male volunteers, a complete finite element model of osteoporosis in L1-S1 was established. After validation, L3-L5 was selected as the surgical segment to construct four surgical models: (a) two stand-alone cages (SA); (b) two cages with unilateral pedicle screws (UPS); (c) two cages with bilateral pedicle screws (BPS); and (d) two cages with bilateral cortical bone trajectory screws (CBT). Segmental range of motion (ROM), cage stress, and internal fixation stress were studied in all surgical models and compared with the intact osteoporosis model. RESULTS: The SA model had a minimal reduction in all motions. The CBT model had the most noticeable reduction in flexion and extension activities, while the reduction in the BPS model was slightly less than that in the CBT model but larger than that in the UPS model. The BPS model had the greatest limitation in left-right bending and rotation, which was greater than the UPS and CBT models. CBT had the smallest limitation in left-right rotation. The cage stress of the SA model was the highest. The cage stress in the BPS model was the lowest. Compared with the UPS model, the cage stress in the CBT model was larger in terms of flexion and LB and LR but slightly smaller in terms of RB and RR. In the extension, the cage stress in the CBT model is significantly smaller than in the UPS model. The CBT internal fixation was subjected to the highest stress of all motions. The BPS group had the lowest internal fixation stress in all motions. CONCLUSIONS: Supplemental internal fixation can improve segmental stability and lessen cage stress in double-level OLIF surgery. In limiting segmental mobility and lowering the stress of cage and internal fixation, BPS outperformed UPS and CBT.

Comprehensive comparison of three techniques for the treatment of adjacent segment degeneration after lumbar fusion.

Purpose: Adjacent segment degeneration (ASD) following lumbar fusion is technically challenging for spine surgeons. Posterolateral open fusion surgery with pedicle screw fixation is an effective way to treat symptomatic ASD with favorable clinical outcomes; however, it is associated with an increased morbidity rate. Therefore, minimally invasive spine surgery is advocated. This study was designed to compare clinical outcomes among patients with symptomatic ASD who underwent percutaneous transforaminal endoscopic discectomy (PTED) with the transforaminal approach, posterior lumbar interbody fusion (PLIF) with cortical bone trajectory screw fixation (CBT-PLIF), and PLIF with traditional trajectory screw fixation (TT-PLIF). Methods: A retrospective study was conductedon 46 patients (26 men and 20 women; average age 60.8 ± 6.78 years) with symptomatic ASD. The patients were treated with three approaches. The operation time, incision length, time to return to work, complications, and the like were compared among three groups. Intervertebral disc (IVD) space height, angular motion, and vertebral slippage were obtained to assess spine biomechanical stability following surgery. The visual analog scale (VAS) score and Oswestry disability index were evaluated at preoperation and 1-week, 3-month, and the latest follow-ups. Clinical global outcomes were also estimated using modified MacNab criteria. Results: The operation time, incision length, intraoperative blood loss, and time to return to work for the PTED group were significantly decreased compared with those for the other two groups (P < 0.05). The radiological indicators in the CBT-PLIF group and TT-PLIF group had better biomechanical stability compared with those in the PTED groups at the latest follow-up (P < 0.05). The back pain VAS score in the CBT-PLIF group was significantly decreased compared with those in the other two groups at the latest follow-up (P < 0.05). The good-to-excellent rate was 82.35% in the PTED group, 88.89% in the CBT-PLIF group, and 85.00% in the TT-PLIF group. No serious complications were encountered. Two patients experienced dysesthesia in the PTED group; screw malposition was found in one patient in the CBT-PLIF group. One case with a dural matter tear was observed in the TT-PLIF group. Conclusion: All three approaches can treat patients with symptomatic ASD efficiently and safely. Functional recovery was more accelerated in the PTED group compared with the other approaches in the short term; CBT-PLIF and TT-PLIF can provide superior biomechanical stability to the lumbosacral spine following decompression compared with PTED; however, compared with TT-PLIF, CBT-PLIF can significantly reduce back pain caused by iatrogenic muscle injury and improve functional recovery. Therefore, superior clinical outcomes were achieved in the CBT-PLIF group compared with the PTED and TT-PLIF groups in the long term.

Safety and Efficacy of Cortical Bone Trajectory Screw Fixation Combined with Facet Fusion for the Treatment of Lumbar Degenerative Disease.

OBJECTIVE: The mainstream lumbar fusion surgeries have various shortcomings, such as complex operation, much invasion, and loss of lumbar function. How to minimize the surgical injury and to achieve better therapeutic effects has become the goal pursued by spine surgeons. This study introduces a cortical bone trajectory (CBT) screw fixation combined with facet fusion (FF), evaluates its safety and efficacy, and explores its advantages, in order to provide a reference for treatment of patients with single-level lumbar stenosis or grade I degenerative spondylolisthesis. METHODS: We retrospectively analyzed the clinical, radiological, and operative data of 167 patients with single-level lumbar stenosis or grade I degenerative spondylolisthesis who underwent FF or transforaminal lumbar interbody fusion (TLIF) from January 2013 to September 2019 in the spine surgery department of the Second Hospital of Shandong University. Patients were divided into four groups according to surgical method: group CBT-FF, CBT screw combined with FF; group PS-FF, pedicle screw (PS) combined with FF; group CBT-TLIF, CBT screw combined with TLIF; and group PS-TLIF, PS combined with TLIF. The operation time, estimated intraoperative blood loss, complications after surgery, visual analog scale (VAS), and Oswestry disability index (ODI) of the four groups were compared. The fusion was evaluated by anteroposterior and lateral X-ray, CT scan, and three-dimensional reconstruction. RESULTS: Twelve months after surgery, the fusion rate of four groups had no significantly statistical differences (p = 0.914). VAS and ODI scores were lower after surgery than before. Low back pain VAS scores 1 week after surgery in group CBT-FF and group CBT-TLIF were significantly lower than those in group PS-FF and group PS-TLIF (pCF/PF = 0.001, pCF/PT = 0.000, pPF/CT = 0.049, pCT/PT = 0.000). Low back pain VAS score 3 months after surgery was significantly lower in group CBT-FF than group PS-FF and group PS-TLIF (pCF/PF = 0.045, pCF/PT = 0.008). ODI score 1 week after surgery was significantly lower in group CBT-FF than group PS-FF, group CBT-TLIF, and group PS-TLIF (pCF/PF = 0.000, pCF/CT = 0.005, pCF/PT = 0.000, pCT/PT = 0.015). ODI score 3 months after surgery was significantly lower in group CBT-FF than group PS-FF, group CBT-TLIF, and group PS-TLIF (pCF/PF = 0.001, pCF/CT = 0.002, pCF/PT = 0.000). Incidence of complications did not significantly differ among the groups. CONCLUSION: CBT screw fixation combined with FF is a safe and efficacious procedure for patients with single-level lumbar stenosis or grade I degenerative spondylolisthesis. This minimally invasive approach of lumbar fusion can be simply and easily performed. Patients who undergo CBT screw fixation combined with FF recovered faster than TLIF.

Freehand screw insertion technique without image guidance for the cortical bone trajectory screw in posterior lumbar interbody fusion: what affects screw misplacement?

OBJECTIVE: Cortical bone trajectory (CBT) screw insertion using a freehand technique is considered less feasible than guided techniques, due to the lack of readily identifiable visual landmarks. However, in posterior lumbar interbody fusion (PLIF), after resection of the posterior anatomy, the pedicles themselves, into which implantation is performed, are palpable from the spinal canal and neural foramen. With the help of pedicle wall probing, the authors have placed CBT screws using a freehand technique without image guidance in PLIF. This technique has advantages of no radiation exposure and no requirement for expensive devices, but the disadvantage of reduced accuracy in screw placement. To address the problem of symptomatic breaches with this freehand technique, variables related to unacceptable screw positioning and need for revisions were investigated. METHODS: From 2014 to 2020, 182 of 426 patients with single-level PLIF were enrolled according to the combined criteria of L4-5 level, excluding cases of revision and isthmic spondylolisthesis; using screws 5.5 mm in diameter; and operated by right-handed surgeons. We studied the number of misplaced screws found and replaced during initial surgeries. Using multiplanar reconstruction CT postoperatively, 692 screw positions on images were classified using previously reported grading criteria. Details of pedicle breaches requiring revisions were studied. We conducted a statistical analysis of the relationship between unacceptable (perforations > 2 mm) misplacements and four variables: level, laterality, spinal deformity, and experiences of surgeons. RESULTS: Three screws in L4 and another in L5 were revised during initial surgeries. The total rate of unacceptable screws on CT examinations was 3.3%. Three screws in L4 and another in L5 breached inferomedial pedicle walls in grade 3 and required revisions. The revision rate was 2.2%. The percentage of unacceptable screws was 5.2% in L4 and 1.7% in L5 (p < 0.05), whereas other variables showed no significant differences. CONCLUSIONS: A freehand technique can be feasible for CBT screw insertion in PLIF, balancing the risks of 3.3% unacceptable misplacements and 2.2% revisions with the benefits of no radiation exposure and no need for expensive devices. Pedicle palpation in L4 is the key to safety, even though it requires deeper and more difficult probing. In the initial surgeries and revisions, 75% of revised screws were observed in L4, and unacceptable screw positions were more likely to be found in L4 than in L5.

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

STUDY DESIGN: This was a prospective randomized controlled trial study. OBJECTIVE: To 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. METHODS: We 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. RESULTS: At 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). CONCLUSION: CBT-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 NUMBER: ChiCTR1900022658. DATE OF REGISTRATION: April 20, 2019.

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.

Minimally Invasive Spine Surgery With Midline Cortical Bone Trajectory Screw Fixation for Lumbar Degenerative Disease in a Retrospective Study of 200 Patients.

OBJECTIVE: Midline lumbar interbody fusion is performed for treatment of various lumbar degenerative diseases, with good clinical outcomes and few complications. However, there are no large-scale or long-term studies regarding midline lumbar interbody fusion. Therefore, the purpose of this study was to evaluate the clinical results of midline lumbar interbody fusion and to compare the results according to surgical level. METHODS: Between January 2013 and December 2015, 200 patients with lumbar degenerative disease undergoing midline lumbar interbody fusion surgery were enrolled. The mean patient age was 69.9 ± 15.8 years (range, 40-85 years). The patients were divided into groups according to surgical level: (1) level 1 operation (136 patients), (2) level 2 operation (43 patients), (3) level 3 operation (12 patients), and (4) level 4 or higher (9 patients). Clinical outcomes, fusion rates, and complications were compared among the 4 groups. RESULTS: All clinical outcomes significantly improved after surgery (measured at 3 years postoperatively) in all groups. Mean fusion rate was 90.5% ± 5.21%. Fusion rate was highest in group I (95.8%) and lowest in group IV (85.2%). There were complications in 17 cases (8.5%). Adjacent segment disease occurred in 16 cases, 5 of which required surgery. Group 1 had 1 case, and group 4 had 4 cases. Screw loosening occurred in 1 case in group 4. There were no cases of infection or mechanical complications. CONCLUSION: This large, single-institution, retrospective study demonstrates favorable clinical outcomes after midline lumbar interbody fusion for lumbar degenerative disease regardless of surgical level.

Surgical outcomes after posterior lumbar interbody fusion using traditional trajectory screw fixation or cortical bone trajectory screw fixation: A comparative study between the polyetheretherketone cage and the same shape titanium-coated polyetheretherketone cage.

OBJECTIVE: To investigate whether or not the fusion rate after posterior lumbar interbody fusion with cortical bone trajectory screw fixation (CBT-PLIF) is lower than after PLIF using traditional trajectory screw fixation (TT-PLIF) and whether or not the titanium-coated polyetheretherketone (PEEK) cage (TiP cage) improves fusion status compared to the same shape uncoated PEEK cage (P cage). METHODS: The subjects were 37 patients undergoing TT-PLIF using P cages (P-TT group), 24 patients undergoing CBT-PLIF using P cages (P-CBT group), 32 patients undergoing TT-PLIF using TiP cages (TiP-TT group), and 20 patients undergoing CBT-PLIF using TiP cages (TiP-CBT group). All patients from the 4 groups underwent our unified PLIF procedure (total facetectomy, subtotal discectomy, and the same bone graft technique using the same shape cages) except for the screw trajectories and the surface materials of the cages. Clinical symptoms were assessed using the Japanese Orthopedic Association (JOA) score before surgery and at 2-year postoperatively. None of age at the time of surgery, gender, fused segment and preoperative JOA score showed significant differences among the 4 groups. On multiplanar reconstruction computed tomography (MPR-CT) at 6months after surgery, vertebral end plate cysts were evaluated and classified into local or diffuse cysts. Fusion status was assessed using both dynamic plain radiographs and MPR-CT at postoperative 2-year. RESULTS: Neither the mean JOA score nor the mean recovery rate of the JOA score at 2-year after surgery showed significant differences among the 4 groups. The incidence of the diffuse cyst (a known predictor of non-union) was 27.0% in the P-TT group, 29.2% in the P-CBT group, 25.0% in the TiP-TT group and 25.0% in the TiP-CBT group (P > 0.05). The fusion rate was 89.2% in the P-TT group, 91.7% in the P-CBT group, 90.6% in the TiP-TT group and 90.0% in the TiP-CBT group (P > 0.05). CONCLUSIONS: After our unified PLIF procedure except for the screw trajectories and the surface materials of the cages, CBT-PLIF resulted in the equivalent fusion rate to TT-PLIF and the TiP cage did not lead to the improved fusion rate compared to the same shape P cage.

[A comparative study on treatment of lumbar degenerative disease with osteoporosis by manual and robot-assisted cortical bone trajectory screws fixation].

OBJECTIVE: To compare the safety and accuracy of manual and robot-assisted cortical bone trajectory (CBT) screws fixation in the treatment of lumbar degenerative diseases with osteoporosis. METHODS: The clinical data of 58 cases of lumbar degenerative disease with osteoporosis treated by CBT screw fixation between February 2017 and February 2019 were analyzed retrospectively. Among them, 29 cases were fixed with CBT screws assisted by robot (group A), 29 cases were fixed with CBT screws by hand (group B). There was no significant difference between the two groups in terms of gender, age, body mass index, lesion type, T-value of bone mineral density, and operative segment ( P>0.05), with comparability. The accuracy of implant was evaluated by Kaito's grading method, and the invasion of CBT screw to the superior articular process was evaluated by Babu's method. RESULTS: The operation time and intraoperative blood loss in group A were significantly less than those in group B ( t=-8.921, P=0.000; t=-14.101, P=0.000). One hundred and sixteen CBT screws were implanted in the two groups. At 3 days after operation, according to the Kaito's grading method, the accuracy of implant in group A was 108 screws of grade 0, 6 of grade 1, and 2 of grade 2; and in group B was 86 screws of grade 0, 12 of grade 1, and 18 of grade 2; the difference was significant ( Z=4.007, P=0.000). There were 114 accepted screws (98.3%) in group A and 98 (84.5%) in group B, the difference was significant ( χ 2=8.309, P=0.009). At 3 days after operation, according to Babu's method, there were 85 screws in grade 0, 3 in grade 1, and 2 in grade 2 in group A; and in group B, there were 91 screws in grade 0, 16 in grade 1, 5 in grade 2, and 4 in grade 3; the difference was significant ( Z=7.943, P=0.000). No serious injury of spinal cord, nerve, and blood vessel was found in the two groups. One patient in group A had delayed cerebrospinal fluid leakage, and 2 patients in group B had mild anemia. Both groups were followed up 10-14 months (mean, 11.6 months). The neurological symptoms were improved, and no screw loosening or fracture was found during the follow-up. CONCLUSION: Compared with manual implantation of CBT screw, robot-assisted spinal implant has higher accuracy, lower incidence of invasion of superior articular process, and strong holding power of CBT screw, which can be applied to the treatment of lumbar degenerative diseases with osteoporosis.

Design and Application of Individualized, 3-Dimensional-Printed Navigation Template for Placing Cortical Bone Trajectory Screws in Middle-Upper Thoracic Spine: Cadaver Research Study.

OBJECTIVE: To evaluate the safety and accuracy of use of a 3-dimensional printed navigation template in the placement of a cortical bone trajectory (CBT) screw in the middle-upper thoracic spine. METHODS: Ten human cadavers were included in the study. Sixty CBT screws were placed on 1 side, using the free-hand technique, and 60 CBT screws were placed on the other side, using the navigation template that was designed and printed using data from 10 cadavers. The safety and accuracy of use of the CBT screws were directly evaluated by radiography and computed tomography. RESULTS: Computed tomography revealed that 2 and 3 of 60 screws, placed using the navigation template, were broken in the medial or lateral areas and in the superior or inferior pedicle wall, respectively. Furthermore, 8 screws were broken in the medial or lateral areas and 11 screws were broken in the superior or inferior pedicle wall when the free-hand technique was used. Radiography revealed that 3 screws in zone I, 55 screws in zone II, and 2 screws in zone III were placed using the navigation template. Furthermore, 7 screws in zone I, 45 screws in zone II, and 8 screws in zone III were placed using the free-hand technique. CONCLUSIONS: In this cadaver study, insertion of the CBT screws in the middle-upper thoracic spine with the assistance of the navigation template was safe and convenient.