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Objective: To analyze whether significant differences exist between free-hand three-dimensional (3D) planning-guided cortical bone trajectory (CBT) screw placement and 3D-printed template-guided CBT screw positioning in terms of accuracy, size of screws, and potential complications., Methods: In this retrospective study, data of adult patients in whom CBT screws were placed for lumbar degenerative pathologies were extracted from a prospectively collected database and analyzed. Patients in whom screws were placed using free-hand 3D planning-guided technique were compared with patients in whom screws were positioned using customized 3D-printed templates. Size of the screws, accuracy, clinical outcomes, and complications were analyzed., Results: The study evaluated 251 patients (1004 screws). The free-hand 3D planning-guided group included 158 patients (632 screws), and the 3D-printed template-guided group included 93 patients (372 screws). The 3D-printed template-guided group involved screws of larger size from L3 to S1. Differences between the 2 groups in terms of accuracy parameters reached statistical significance (P ≤ 0.05)., Conclusions: With the use of 3D patient-matched template guides, mean diameter and length of CBT screws could be safely increased due to improved accuracy of screw placement. Based on previous evidence regarding CBT biomechanical properties, these advantages could allow increased fixation strength over traditional convergent pedicle screw trajectories. Further biomechanics studies are needed., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: The introduction of intraoperative computed tomography (iCT) could improve the surgical results of C1-C2 stabilization by Goel-Harms, especially in patients with complex deformities. This study aims to investigate the impact of iCT on the accuracy of C1-C2 screw positioning and to develop a score based on multiparametric analysis of imaging data (Cervical Screw Placement Accuracy score [CSPAs])., Methods: Twenty-one patients were retrospectively evaluated. The data obtained with the use of an iCT were compared with the incidence of cases of malpositioning in the literature. Multiparametric imaging criteria were developed: the 82 screw positions were evaluated using the CSPA criteria and 2 additional variables. The CSPAs was obtained from the aggregation of the CSPAs criteria: optimal (CSPAs ≥8), suboptimal (CSPAs = 6-7), malpositioned (CSPAs ≤5)., Results: The average incidence of malpositioning in C1-C2 arthrodesis decreased from 13% without iCT to 1.2% with the aid of iCT, considering a monoparametric value. The CSPAs analysis shows a greater discretion and higher number of well-defined categories of the accuracy of C1-C2 screw position: optimal, 80.3%; suboptimal, 17.1%; and malposition, 2.6%. A correlation was observed between the accuracy of the positioning of both right and left screws in C2. Furthermore, the anatomic site of C2 screws was found to be a predictor of cortical invasion., Conclusions: The results suggest that the introduction of the iCT is associated with a consistent improvement of the accuracy in the positioning of the screws. A multiparametric score (CSPAs) could improve the assessment of screw placement., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Cortical Bone Trajectory screws allow a limited soft tissue dissection with mechanical properties comparable to traditional pedicle screws. However, clinical results are still reported on limited samples. The study aimed to evaluate perioperative and mid-term follow up outcomes, clinical results and complications in 238 consecutive patients underwent CBT fusion for degenerative lumbosacral disease. Pre- and intraoperative data, clinical outcomes and complications were collected. The patients were stratified in three groups. The original technique was performed in the first 43 cases without a preoperative CT scan planning. The second group includes the patients who underwent preoperative CT scan for entry point and screw trajectory planning (158 patients). Surgical procedures in the last group were performed with patient-matched 3D printed guide (37 patients). The accuracy in screws positioning was evaluated on postoperative CT scan. The mean follow-up was 32.3 months. Mean ODI and VAS index improved with statistical significance. Mean procedural time was 187, 142 and 124 min in the three subgroups. The total amount of recorded complications was 4.2% (16.3%, 3.8% and 0.0% respectively). Screws entirely within the cortex of the pedicle were 78.9%, 90.5% and 93.9% in the three groups. Fusion was obtained in 92.4% of cases. The CBT technique is a safe procedure, especially with an accurate preoperative CT scan-based planning. This seems more evident with the 3D template patient-matched guide. More studies are needed to directly compare traditional pedicle screws and CBT screws on long-term outcomes., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In spinal oncology traditional titanium implants could significantly impair evaluation of postoperative imaging because of artifacts, potentially affecting proper planning and execution of radiotherapy and adequate radiological follow-up to rule out progression of the disease. This is why carbon fiber reinforced (CFR)-PEEK implants have been developed for spinal fixation. The advantages of this system include fewer artifacts on imaging, potentially improving the execution and quality of radiotherapy, with also a reduced scattering effect to neighboring tissues. A comparative clinical and radiological study between new CFR-PEEK and standard titanium implants is described. Data recorded for each case included patient demographics, clinical, radiological and surgical data, intra- and postoperative complications, follow-up information. The goal of this study was to verify the safety and effectiveness of CFR-PEEK devices compared to standard titanium implants. A total number of 78 patients were reviewed. 36 patients underwent CFR-PEEK fixation, while titanium implants were used for 42 patients. Functional recovery was obtained in both groups and registered at last follow-up in terms of axial pain and neurological status. No significative differences were found between the two groups in terms of post-operative clinical complications and hardware-related complications. CFR-PEEK implants constitute a feasible and effective way to restore stability in metastatic spine tumors. This study found a non inferior favorable profile in terms of intraoperative and postoperative complications and functional recovery, compared to titanium. Further prospective studies are needed to clarify the potential oncological advantage of their radiolucency., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The use of cortical bone trajectory (CBT) pedicle screws for posterior fixation and fusion seems to constitute a viable alternative for spinal procedures, with the potential to mitigate risks, be minimally invasive, and cause less tissue damage than the traditional technique. This review analyzes the literature regarding CBT according to the rate of evidence of articles and their main focus. CBT has proved to be a safe and viable option for screw fixation in spine surgery. Given the denser bone interception, high-quality biomechanics studies show equal or even better properties compared with classic pedicle screw fixation, depending on several factors such as screw size and length. Through the years, surgical technique has improved to gain a longer and safer trajectory than first described. Level 2 and 3 clinical studies suggest equal clinical and radiologic outcomes compared with pedicle trajectory fixation, but high-quality, level 1, randomized controlled trials are needed to confirm these results., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Among the posterior techniques, the use of cervical interfacet spacers (CISs) represents a promising technology whose potentialities are still being studied. The purpose of the present review was to assess the available data on CISs., Methods: A search on PubMed was performed. The search terms were "cervical interfacet spacers," "facet spacers," "DTRAX facet system," "Goel facet spacer," "pseudarthrosis," "cervical lordosis," "iatrogenic kyphosis," "cervical foraminal decompression," "cervical biomechanics," "atlantoaxial instability," and "subaxial instability.", Results: Mechanical studies have shown that stand-alone CISs promoted stiffness in all directions, except for extension. Foraminal distraction was recorded in 86% of the cases. Clinical studies have shown that the use of CISs could promote successful arthrodesis, given the large surface area affected by fusion and decreasing the need for autografts. The effectiveness for the treatment of radiculopathy has been confirmed by several clinical studies. In a series of 154 levels of implanted CISs, no evidence of significant loss of cervical lordosis was identified. CISs could help in enhancing fusion in C1-C2 fixation., Conclusions: Biomechanical studies on specimens showed a positive trend in increasing stiffness of the cervical spine, despite some controversial results. In clinical studies, facet distraction was shown to be a safe and valid option for clinical indirect decompression, although longer follow-up is required for confirmation. No evidence of the loss of cervical lordosis has been recorded. The long-term effects and CIS use in revision procedures as adjuvant implants to treat pseudarthrosis or atlantoaxial instability are currently under investigation, and further studies are needed., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Pedicle screw instrumentation is a standard procedure in lumbar spinal fusion. The cortical bone trajectory (CBT) screw is an alternative technique, less invasive but harder to perform. The identification of the entry point and the appropriate direction can be tricky especially to the surgeons just at the beginning. Therefore, the aim of this study is to evaluate the reliability of preoperative computed tomography (CT) planning in the CBT screw placement., Methods: We retrospectively evaluated 82 patients who underwent a single-level posterior lumbar arthrodesis with CBT screws. The correct entry point and the best trajectory were identified on a 3-dimensional (3D) multiplanar reconstruction CT view. The concordance between achieved and planned trajectories was assessed on a postoperative CT., Results: A total of 328 screws was positioned. The average entry point distance from the target was 1.1 mm (standard deviation, ±0.15 mm). In 301 screws (91.8%), the obtained trajectory differed no more than 2° from the planned one. No screws misplaced or new neurological deficit was recorded., Conclusions: The CBT screw placement is a great alternative to the pedicle screw. Accurate preoperative 3D planning is useful to predict the entry point and the direction with accuracy similar to navigation systems, avoiding its costs and technical difficulties. The 3D CT planning is helpful in the customization of spine surgery, and the results underline the radiological reliability of this technique., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Introduction: A prospective comparative study between classical posterior interbody fusion with peduncular screws and the new technique with divergent cortical screws was conducted., Material and Methods: Only patients with monosegmental degenerative disease were recruited into this study. We analyzed a cohort of 40 patients treated from January 2015 to March 2016 divided into 2 groups (20 patients went to traditional open surgery and 20 patients under mini-invasive strategy). Primary endpoints of this study are fusion rate and muscular damage; secondary endpoints analyzed were three different clinical scores (ODI, VAS, and EQ) and the morbidity rate of both techniques., Results: There was no significant difference in fusion rate between the two techniques. In addition, a significant difference in muscular damage was found according to the MRI evaluation. Clinical outcomes, based on pain intensity, Oswestry Disability Index status, and Euroquality-5D score, were found to be also statistically different, even one year after surgery. This study also demonstrated a correlation between patients' muscular damage and their clinical outcome., Conclusions: Cortical bone trajectory screws would provide similar outcomes compared to pedicle screws in posterior lumbar interbody fusion at one year after surgery, and this technique represents a reasonable alternative to pedicle screws.

Background: Cervical sagittal alignment parameters are essential to plan stages of surgery. The aims of this study were to evaluate the relationship between cervical sagittal alignment parameters and surgical outcomes after anterior cervical arthrodesis; to identify parameters linked to a better outcome; to determine the role of the T1 slope, C7 slope, cervical lordosis, and C2-C7 plumb line; and to describe an innovative method to calculate cervical lordosis. A cohort of 70 patients without cervical kyphosis was included in our retrospective study. We analyzed C7 slope, T1 slope, cervical lordosis, and the C2-C7 sagittal vertical axis (SVA). Clinical postoperative outcomes were evaluated with the Neck Disability Index (NDI) and Visual Analog Scale (VAS) score., Results: Significant correlation was found between the C2-C7 SVA, C7 slope, T1 slope and the CL/C7 slope. Statistically significant differences were found between group 1 (NDI = 0; VAS = 0) and group 3 (NDI > 17; VAS > 5) regarding C2-C7 SVA (P = 0.0026), C7 slope (P = 0.0014), T1 slope (P = 0.0095) and CL/C7slope (P = 0.0012). A value less than 25 mm found in the C2-C7 SVA correlate with positive outcomes. C7 slope correlated with NDI and VAS (P = 0.0014). CL/C7 slope ratio is significantly correlated to NDI and VAS scores (ratio: -0.52; P = 0.0012). Patients with CL/C7 slope greater than 0.7 had better clinical outcomes., Conclusions: Sagittal parameters are directly correlated with clinical outcome. If C7 slope increases, higher cervical lordosis is necessary to obtain a good outcome. CL/C7 slope (0.7) multiplied by C7 slope can determine the ideal lordosis., (Copyright © 2016 Elsevier Inc. All rights reserved.)