Posterior Lumbar Interbody Fusion with 3D-Navigation Guided Cortical Bone Trajectory Screws for L4/5 Degenerative Spondylolisthesis: 1-Year Clinical and Radiographic Outcomes

The accuracy of cortical bone trajectory screw placement guided by spinous process clamp hardware in lumbar spinal surgery: a retrospective study

This study aimed to assess the accuracy of cortical bone trajectory (CBT) screws placement guided by a spinous process clamp (SPC) guide. A total of 32 patients who received single-level midline lumbar fusion (MIDLF) surgery between June 2019 and January 2020 were retrospectively analyzed and divided into free-hand (FH) and SPC-guided groups according to the surgical approach. In the FH group, CBT screws was implanted with the assistance of fluoroscopy, while in the SPC group, CBT screws was implanted using the SPC navigator hardwire. A total of 128 screws were assessed in this study, with higher rates of clinically acceptable screw placement (grades A and B) and grade A screws in the SPC group than in the FH guide group (92.2% vs. 79.7%, P = 0.042 and 54.7% vs. 35.9%, P = 0.033, respectively). Misplacement screws (grades C, D, and E) occurred more often in the FH group than in the SPC guide group (20.3% vs. 7.8%, P = 0.042). The incidence of proximal facet joint violation (FJV) was higher in the FH group than in the SPC group (15.6% vs. 3.1%, P = 0.030). The radiation dose and time in the SPC guide group were comparable to those in the FH group (P = 0.063 and P = 0.078). The average operative time was significantly longer in the SPC guide group than in the FH group (267.8 ± 45.5 min vs. 210.9 ± 44.5 min, P = 0.001). Other clinical parameters, such as the average bone mineral density (BMD), intraoperative blood loss, and postoperative hospital stay, were not significantly different. Oswestry disability index (ODI) and back pain visual analogue scale (VAS) scores were significantly improved in both groups compared with preoperatively. SPC guided screw placement was more accurate than the fluoroscopy-assisted FH technique for single-level MIDLF at L4/5. Patients undergoing SPC-guided screw placement can achieve similar clinical outcomes as the fluoroscopy-assisted FH technique.

Accuracy of cortical bone trajectory screw fixation guided by spinous process clamp guide in lumbosacral vertebrae: A cadaver study

BACKGROUND

The purpose of this study was to access the accuracy of cortical bone trajectory screw placement guided by spinous process clamp (SPC).

METHODS

Eight formalin-treated cadaveric lumbar specimens with T12-S1 were used. A total of 96 screws were implanted in eight lumbar specimens.

RESULTS

In the freehand (FH) group, clinically acceptable placement (grade A and B) was 40 screws (83.3%), meanwhile 44 screws (91.7%) in the SPC guide group (p = 0.217). The grade A screws in the SPC guide group were much more than that in the FH group (n = 40 vs. n = 31, p = 0.036). The misplacement screws (grade C, D, and E) and proximal facet joint violation (FJV) in the SPC group was comparable to the FH group.

CONCLUSIONS

This cadaveric study demonstrate that implanting CBT screws guided by SPC guide was more accuracy and reduces severe deviations in important directions.

Cortical screw placement with a spinous process clamp guide: a cadaver study accessing accuracy

Background and objective

The Cortical Bone Trajectory (CBT) technique provides an alternative method for fixation in the lumbar spine in patients with osteoporosis. An accuracy CBT screw placement could improve mechanical stability and reduce complication rates.

Purpose

The purpose of this study is to explore the accuracy of cortical screw placement with the application of implanted spinous process clip (SPC) guide.

Methods and materials

Four lumbar specimens with T12-S1 were used to access the accuracy of the cortical screw. The SPC-guided planning screws were compared to the actual inserted screws by superimposing the vertebrae and screws preoperative and postoperative CT scans. According to preoperative planning, the SPC guide was adjusted to the appropriate posture to allow the K-wire drilling along the planned trajectory. Pre and postoperative 3D-CT reconstructions was used to evaluate the screw accuracy according to Gertzbein and Robbins classification. Intraclass correlation coefficients (ICCs) and Bland–Altman plots were used to examine SPC-guided agreements for CBT screw placement.

Results

A total of 48 screws were documented in the study. Clinically acceptable trajectory (grades A and B) was accessed in 100% of 48 screws in the planning screws group, and 93.8% of 48 screws in the inserted screws group (p = 0.242). The incidence of proximal facet joint violation (FJV) in the planning screws group (2.1%) was comparable to the inserted screws group (6.3%) (p = 0.617). The lateral angle and cranial angle of the planned screws (9.2 ± 1.8° and 22.8 ± 5.6°) were similar to inserted screws (9.1 ± 1.7° and 23.0 ± 5.1°, p = 0.662 and p = 0.760). Reliability evaluated by intraclass correlation coefficients and Bland–Altman showed good consistency in cranial angle and excellent results in lateral angle and distance of screw tip.

Conclusions

Compared with preoperative planning screws and the actually inserted screws, the SPC guide could achieve reliable execution for cortical screw placement.

Minimally Invasive Spine Surgery: An Overview

Spinal surgery is undergoing a major transformation toward a minimally invasive paradigm. This shift is being driven by multiple factors, including the need to address spinal problems in an older and sicker population, as well as changes in patient preferences and reimbursement patterns. Increasingly, minimally invasive surgical techniques are being used in place of traditional open approaches due to significant advancements and implementation of intraoperative imaging and navigation technologies. However, in some patients, due to specific anatomic or pathologic factors, minimally invasive techniques are not always possible. Numerous algorithms have been described, and additional efforts are underway to better optimize patient selection for minimally invasive spinal surgery (MISS) procedures in order to achieve optimal outcomes. Numerous unique MISS approaches and techniques have been described, and several have become fundamental. Investigators are evaluating combinations of MISS techniques to further enhance the surgical workflow, patient safety, and efficiency.

Clinical and radiological results of treating lumbar spondylosis with cortical bone trajectory screws

The cortical bone trajectory screws technique (CBTT) is a popular minimally invasive spine surgery. Few studies have reported long-term outcomes. We aimed to evaluate the complication profile and long-term follow-up results of patients with lumbar degenerative disease treated with the CBTT.This retrospective analysis included the first 40 consecutive patients that underwent the CBTT. The indication for surgery was critical stenosis of the intervertebral foramen, which required removal of the entire intervertebral joint, on at least 1 side, during decompression.The last follow-up showed minimal clinically important differences in the numerical rating scale of leg pain, the numerical rating scale of back pain, and the Oswestry Disability Index, in 97%, 95%, and 95% of patients, respectively. Thirty-nine patients completed long-term radiological follow-up. Computed tomography demonstrated solid bone union on 47 (92%) operated levels, collapsed union on 2 (4%) levels, nonunion on 1 (2%) level, and 1 (2%) patient was lost to follow-up. Seven patients experienced complications (4 hardware-related). Three patients required 4 revision surgeries.The CBTT effectively achieved spinal fusion; over 90% of patients achieved clinical improvement at a mean follow-up of 4.4 years (range: 3-5.75 years).

Simulation with 3D Neuronavigation for Learning Cortical Bone Trajectory Screw Placement

BACKGROUND AND OBJECTIVE

 Learning a new technique in neurosurgery is a big challenge especially for trainees. In recent years, simulations and simulators got into the focus as a teaching tool. Our objective is to propose a simulator for placement of cortical bone trajectory (CBT) screws to improve results and reduce complications.

METHODS

 We have created a platform consisting of a sawbone navigated with a 3D fluoroscope to familiarize our trainees and consultants with CBT technique and later implement it in our department. Objective Structured Assessment of Technical Skills (OSATS) and Physician Performance Diagnostic Inventory Scale (PPDI) were obtained before and after the use of the simulator by the five participants in the study. Patients who were operated on after the implementation of the technique were retrospectively reviewed.

RESULTS

 During the simulation, there were 4 cases of pedicle breach out of 24 screws inserted (16.6%). After having completed simulation, participants demonstrated an improvement in OSATS and PPDI (p = 0.039 and 0.042, respectively). Analyzing the answers to the different items of the tests, participants mainly improved in the knowledge (p = 0.038), the performance (p = 0.041), and understanding of the procedure (p = 0.034). In our retrospective series, eight patients with L4-L5 instability were operated on using CBT, improving their Oswestry Disability Index (ODI) score (preoperative ODI 58.5 [SD 16.7] vs. postoperative ODI 31 [SD 13.4]; p = 0.028). One intraoperative complication due to a dural tear was observed. In the follow-up, we found a case of pseudoarthrosis and a facet joint violation, but no other complications related to misplacement, pedicle fracture, or hardware failure.

CONCLUSION

 The simulation we have created is useful for the implementation of CBT. In our study, consultants and trainees have valued very positively the learning obtained using the system. Moreover, simulation facilitated the learning of the technique and the understanding of surgical anatomy. We hope that simulation helps reducing complications in the future.

Comparison of facet joint violation in lumbar posterior spinal instrumentation using different techniques including cortical bone trajectory

Study background:

A retrospective study to compare the rate of facet joint violation (FJV) in lumbar posterior spinal instrumentation using open pedicle screw, percutaneous pedicle screw, and cortical bone trajectory (CBT) technique. CBT is a new posterior spinal instrumentation technique in which a more caudal entry point can minimize iatrogenic damage to the cranial facet joint. Only one recent study reports incidence of FJV of 11%; however, no previous reports comment on radiological outcomes comparing to traditional open and percutaneous screws.

Methods:

We reviewed 90 patients who underwent lumbar posterior spinal instrumentation from January 2016 to June 2017. Postoperative computer tomography scans were performed to evaluate FJV. Incidence of FJV was graded by three reviewers according to Seo classification.

Results:

Totally, 446 screws (open 43.4%, percutaneous 37.8%, CBT 18.9%) were inserted. Among these, 6.3% (28/446) had screw head or rod in contact with facet joint and 0.9% (4/446) had screws directly invaded the facet joint. Overall, FJV was 7.2% (CTB = 3.4%, open = 10.4%, and percutaneous = 4.5%, p = 0.075).

Conclusion:

CBT technique has potential advantage in reducing FJV. It has a unique entry site at lateral aspect of pars interarticular with a caudomedial to craniolateral pathway. It is a reasonable alternative to open or percutaneous techniques in lumbar posterior spinal instrumentation.

Cortical Trajectory Pedicle Screws for the Fixation of Traumatic Thoracolumbar Fractures

Objective

Cortical bone trajectory pedicle screws (CBT) have a different trajectory compared to traditional pedicle screws (PS) and they may confer biomechanical advantages in some patient populations. We hypothesize that the placement of CBT in traumatic thoracolumbar fractures could be an alternative technique to the traditional utilization of PS.

Methods

Single surgeon, retrospective study was performed at a Level 1 Trauma Center from 2013 to 2017. All patients aged between 18 and 90 years with operative AO classification A, B, and C traumatic thoracolumbar fractures were included. Patients with pathological fractures, active spinal infections, or history of vertebral augmentation were excluded. Age, injury severity score (ISS), AO classification, operative time, estimated blood loss (EBL), length of stay (LOS), and presence of proximal junctional kyphosis (PJK) or construct failure were compared between CBT and PS groups. The PS group was further separated into open reduction internal fixation (ORIF) and minimally invasive spine (MIS) groups. All CBT and ORIF cases were completed via open incisions allowing arthrodesis of the involved lamina and facet joints whereas no arthrodesis was completed in the MIS patients. Choice of technique was at the attending surgeon’s discretion.

Results

The study included 71 patients, out of which 12 received CBT and 59 received PS. Of the 59 PS patients, 39 were ORIF and 20 were MIS. The average operative time was 22.9 minutes less in CBT compared to ORIF (p = 0.24). EBL was 337.50 mL for CBT, 184.33 mL for MIS, and 503.33 mL for ORIF (p = 0.01) demonstrating that MIS technique results in a significantly reduced blood loss. However, EBL was comparable for CBT versus MIS (p > 0.05). ISS was not significantly different between the three groups (p = 0.89). LOS was 4.06 days fewer for CBT patients compared to ORIF patients (p = 0.36). There was one case of construct failure as well as one case of incisional site infection in the PS group, but none were found in the CBT group. Instances of PJK complications were determined by the change in the Cobb angle over time and they were not statistically different between the three groups (p = 0.68).

Conclusions

CBT is noninferior to PS in the fixation of unstable adult traumatic thoracolumbar fractures. With the exception of EBL, CBT was not statistically different compared to MIS and ORIF. This study establishes a precedent to expand the application of this new technique and investigate with larger sample sizes.