Safety and efficacy of navigated trocarless pedicle screw placement: Technical note

Biomechanical effects of posterior lumbar interbody fusion with vertical placement of pedicle screws compared to traditional placement

BACKGROUND

The pedicle screw technique is widely employed for vertebral body fixation in the treatment of spinal disorders. However, traditional screw placement methods require the dissection of paraspinal muscles and the insertion of pedicle screws at specific transverse section angles (TSA). Larger TSA angles require more force to pull the muscle tissue, which can increase the risk of surgical trauma and ischemic injury to the lumbar muscles.

AIM

To study the feasibility of zero-degree TSA vertical pedicle screw technique in the lumbosacral segment.

METHODS

Finite element models of vertebral bodies and pedicle screw-rod systems were established for the L4-S1 spinal segments. A standard axial load of 500 N and a rotational torque of 10 N/m were applied. Simulated screw pull-out experiment was conducted to observe pedicle screw resistance to pull-out, maximum stress, load-displacement ratio, maximum stress in vertebral bodies, load-displacement ratio in vertebral bodies, and the stress distribution in pedicle screws and vertebral bodies. Differences between the 0-degree and 17-degree TSA were compared.

RESULTS

At 0-degree TSA, the screw pull-out force decreased by 11.35% compared to that at 17-degree TSA (P < 0.05). At 0-degree and 17-degree TSA, the stress range in the screw-rod system was 335.1-657.5 MPa and 242.8-648.5 MPa, separately, which were below the fracture threshold for the screw-rod system (924 MPa). At 0-degree and 17-degree TSA, the stress range in the vertebral bodies was 68.45-78.91 MPa and 39.08-72.73 MPa, separately, which were below the typical bone yield stress range for vertebral bodies (110-125 MPa). At 0-degree TSA, the load-displacement ratio for the vertebral bodies and pedicle screws was slightly lower compared to that at 17-degree TSA, indicating slightly lower stability (P < 0.05).

CONCLUSION

The safety and stability of 0-degree TSA are slightly lower, but the risks of screw-rod system fracture, vertebral body fracture, and rupture are within acceptable limits.

Anterior To Psoas lumbar and lumbosacral combined with posterior reconstruction in Adult Spinal Deformity: A bicentric European study

Introduction

Lateral lumbar fusion via the trans-psoas approach is popular in adult deformity reconstruction. To overcome its limitations (neurological damage to the plexus and lack of applicability to the lumbosacral junction), a modified anterior-to-psoas (ATP) approach has been described and used.

Research question

To investigate the results of ATP lumbar and lumbosacral fusion, in a cohort of adult patients treated with combined anteroposterior approaches for adult spinal deformity (ASD).

Materials and methods

ASD patients surgically treated at two tertiary spinal centres were followed up. Forty patients were treated with combined ATP and posterior surgery: 11 with open lumbar lateral interbody-fusions (lumbotomy LLIF) and 29 with lesser invasive oblique lateral interbody-fusions (OLIF). Preoperative demographics, aetiology, clinical characteristics, and spinopelvic parameters were comparable between the two cohorts.

Results

At a minimum 2-year follow-up, both cohorts showed significant improvements in patient reported outcome measures (PROMs), i.e. Visual Analogue Scale and Core Outcome Measures Index, as well as radiological parameters, with no significant differences based on the type of surgical approach. No significant differences were found in major (P ​= ​0.457) and minor (P ​= ​0.071) complications between the two cohorts.

Discusson and conclusion

Anterolateral lumbar interbody fusions, whether performed via a direct or oblique approach, proved to be safe and effective adjuvants to posterior surgery in patients with ASD. No significant complication differences were noted between techniques. In addition, the anterior-to-psoas approaches limited the risks of post-operative pseudoarthrosis by providing solid anterior support to lumbar and lumbosacral segments, demonstrating a positive impact on PROMS.

Fluoroscopy-Assisted Freehand Versus 3D-Navigated Imaging-Assisted Pedicle Screw Insertion: A Multicenter Study

INTRODUCTION

Pedicle screw placement is a widely accepted surgical procedure for spinal fixation. Despite increases in knowledge about and expertise in pedicle screw insertion techniques, overall reported screw misplacement rates are still high. Spinal neuronavigation and intraoperative computed tomography (CT) imaging improves the accuracy and safety of pedicle screw placement through the continuous monitoring of screw trajectory. The purpose of this study is to compare pedicle screw placement under an O-arm intraoperative imaging system assisted by the StealthStation navigation system with screw placement under conventional fluoroscopy (C-arm).

METHODS

For 222 patients, 1288 implanted pedicle screws in total were evaluated between 2018 and 2020. All patients underwent pedicle screw placement in the thoracic and lumbosacral regions through a posterior approach. Moreover, 107 patients (48.2%), 48 men and 59 women, underwent freehand screw placement under conventional fluoroscopy (C-arm group), whereas 115 patients (51.8%), 53 men and 62 women, underwent pedicle screw insertion under O-arm guidance with the help of the StealthStation neuronavigation system (Medtronic Navigation, Louisville, CO, USA) (O-arm group). Data were recorded and retrospectively analyzed. The accuracy of pedicle screw placement was postoperatively examined by using CT imaging and analyzed according to the Gertzbein-Robbins classification.

RESULTS

Of the 1288 pedicle screws, 665 (51.6%) were placed with C-arm image-guided assistance with a mean of 6.21 ± 2.1 screws per patient and 643 (48.4%) with O-arm image-guided assistance with a mean of 5.59 ± 1.6 screws. The average time for the screw placement procedure was 3:57 ± 1:07 h in the C-arm group and 4:21 ± 1:41 h in the O-arm group. A correct screw placement was detected in 92.78% of patients in the C-arm group and in 98.13% of patients in the O-arm group. Medial cortical breach was shown in 13 Grade B screws (1.95%), 19 Grade C (2.86%), 14 Grade D (2.11%), and two Grade E (0.3%) in the C-arm group, whereas this was shown in 11 Grade B screws (1.71%) and one Grade C (0.16%) in the O-arm group. Lateral breach occurred in eight screws in both groups. Anterior vertebral body breach was shown in eight screws in the C-arm group, whereas it was shown in four screws in the O-arm group. Reoperation for screw misplacement was mandatory in five patients in the C-arm group and two patients in the O-arm group.

CONCLUSION

Pedicle screw placement under an O-arm intraoperative imaging system assisted by spinal navigation showed greater accuracy compared with placement under conventional fluoroscopic control, thus avoiding the onset of major postoperative complications. Notably, a reduction in medial and anterior breaches has been demonstrated.

Multilevel Corpectomy for Subaxial Cervical Spondylodiscitis: Literature Review and Role of Navigation, Intraoperative Imaging and Augmented Reality

BACKGROUND

Subaxial cervical spine spondylodiscitis represents a real challenge in spine surgery. In later stages multiple spinal metamers can the interested by the pathological infection and the alteration of the spinal stability leading to spinal deformity. There is scant literature on subaxial cervical spondylodiscitis management and especially on ≥three-level cervical corpectomies. The authors conducted a literature search on this specific topic and presented an emblematic case of a patient treated with circumferential cervical fixation and four-level cervicothoracic corpectomy.

MATERIALS AND METHODS

A comprehensive literature review was performed using the combined Medical Subject Headings (MeSH) terms (multilevel) AND (sub axial spine OR cervical spine) AND (spine osteomyelitis OR spinal osteomyelitis), to search in the PubMed and Scopus databases. Our case was also included in this literature review. From our literature search the authors selected 13 papers, eight were excluded because they did not match our inclusion criteria (the involvement of only one or two levels, or did not perform corpectomy, discectomy, or cervical spine localization). The authors also presented a 71-year-old patient, in poor general clinical status who underwent several cage repositioning, with a final four-level corpectomy (C5, C6, C7, and T1), expandable C5-T1 cage positioning and C4-T2 anterior plating performed merging augmented reality, neuronavigation and intraoperative imaging.

RESULTS

This systematic review included 28 patients treated with ≥ three-level corpectomy (11 patients with three-level corpectomy, 15 patients with four-level corpectomy, and 2 patients with six-level corpectomy), 6 women, 5 men, and 17 not reported specifically, with a mean age of 55.9 years (range: 44-72 years). The combined anterior and posterior approach was taken in all but one case, which was treated with the anterior approach only. In one case of six-level cervicothoracic corpectomy, sternotomy was necessary. All reported patients recovered after surgery, except one who died after nosocomial pneumonia. No major intraoperative complications were reported. Usual postoperative complications include wound hematoma, pneumonia, subsidence, epidural hematoma, dural leakage, dysphagia, soft tissue swelling. The mean follow-up time was 31.9 months (range: 8-110 months).

CONCLUSION

According to the literature search performed by the authors, multilevel corpectomies for cervical spinal osteomyelitis is a safe and effective complex surgical procedure, even in extended procedures involving up to six levels or those at the cervicothoracic junction. The use multimodal navigation merging intraoperative imaging acquisition, navigation, and augmented reality may provide useful information during implant positioning in complex and altered anatomy and for assessing the best final result.

Navigation-assisted extraforaminal lumbar disc microdiscectomy: Technical note

Background:

Extraforaminal lumbar disc herniation (ELDH) amounts of 7%–12% of all lumbar disc herniations. Although they have already been widely described, an optimal treatment is still under discussion in the literature.

Objective:

We describe a novel application of navigation using 2D/3D imaging system to plan an adequate surgical trajectory and performing a neuronavigated microdiscectomy in ELDH that has not been previously described.

Methods:

This is a retrospective study in a single institution. Between February 2017 and July 2020, a total of 12 patients (7 males and 5 females), with a mean age of 56 years (range 49–71 years), have been treated because of ELDH through a far lateral microdiscectomy using 2D/3D imaging system-assisted neuronavigation (O-arm).

Results:

No intraoperative and/or postoperative complications were recorded. Patients presented a mean preoperative Visual Analog Scale (VAS) score of 7.83 ± 0.83 (range 7–9). At the day of discharge, leg pain VAS score effectively improved, decreasing to a mean value of 1.83 ± 0.83 (range 1–3). Further, low back and radicular pain improvement was recorded at 1-, 6-, and 12-month follow-up, respectively.

Conclusion:

We described a novel use of 2D/3D imaging system navigation in the microsurgical treatment of ELDH that has not previously reported. This technique is safe and effective and provides more intraoperative details compared to fluoroscopy, which can be crucial for the success of the procedure and to reduce complications and particularly indicated in complex cases with altered anatomy.