Accuracy of image-guided pedicle screw placement using intraoperative computed tomography-based navigation with automated referencing. Part II: thoracolumbar spine

Neuronavigation in minimally invasive spine surgery

OBJECT

Parallel advancements in image guidance technology and minimal access techniques continue to push the frontiers of minimally invasive spine surgery (MISS). While traditional intraoperative imaging remains widely used, newer platforms, such as 3D-fluoroscopy, cone-beam CT, and intraoperative CT/MRI, have enabled safer, more accurate instrumentation placement with less radiation exposure to the surgeon. The goal of this work is to provide a review of the current uses of advanced image guidance in MISS.

METHODS

The authors searched PubMed for relevant articles concerning MISS, with particular attention to the use of image-guidance platforms. Pertinent studies published in English were further compiled and characterized into relevant analyses of MISS of the cervical, thoracic, and lumbosacral regions.

RESULTS

Fifty-two studies were included for review. These describe the use of the iso-C system for 3D navigation during C1-2 transarticular screw placement, the use of endoscopic techniques in the cervical spine, and the role of navigation guidance at the occipital-cervical junction. The authors discuss the evolving literature concerning neuronavigation during pedicle screw placement in the thoracic and lumbar spine in the setting of infection, trauma, and deformity surgery and review the use of image guidance in transsacral approaches.

CONCLUSIONS

Refinements in image-guidance technologies and minimal access techniques have converged on spinal pathology, affording patients the ability to undergo safe, accurate operations without the associated morbidities of conventional approaches. While percutaneous transpedicular screw placement is among the most common procedures to benefit from navigation, other areas of spine surgery can benefit from advances in neuronavigation and further growth in the field of image-guided MISS is anticipated.

Marking wire placement for improved accuracy in thoracic spinal surgery

OBJECTIVE

To present an innovative approach that does not rely on intraoperative X-ray imaging for identifying thoracic target levels and critically appraise its value in reducing the risk of wrong-level surgery and radiation exposure.

METHODS

96 patients admitted for surgery of the thoracic spine were prospectively enrolled, undergoing a total of 99 marking wire placements. Preoperatively a flexible marking wire derived from breast cancer surgery was inserted with computed tomography (CT) guidance at the site of interest--the wire was then used as an intraoperative guidance tool.

RESULTS

Wire placement was considered successful in 96 cases (97%). Most common pathologies were tumors (62.5%) and degenerative disorders (16.7%). Effective doses from CT imaging were significantly higher for wire placements in the upper third of the thoracic spine compared to the lower two thirds (p = 0.015). Radiation exposure to operating room personnel could be reduced by more than 90% in all non-instrumented cases. No adverse reactions were observed, one patient (1.04%) underwent surgical revision due to an epifascial empyema. No wires had to be removed due to lack of patient compliance or infection.

CONCLUSIONS

This is a safe and practical approach to identify the level of interest in thoracic spinal surgery employing a marking wire. Its application merits consideration in any spinal case where X-ray localization could prove unsafe, particularly in cases lacking bony pathologies such as intradural tumors.

Navigation, robotics, and intraoperative imaging in spinal surgery

Spinal navigation is a technique gaining increasing popularity. Different approaches as CT-based or intraoperative imaging-based navigation are available, requiring different methods of patient registration, bearing certain advantages and disadvantages. So far, a large number of studies assessed the accuracy of pedicle screw implantation in the cervical, thoracic, and lumbar spine, elucidating the advantages of image guidance. However, a clear proof of patient benefit is missing, so far. Spinal navigation is closely related to intraoperative 3D imaging providing an imaging dataset for navigational use and the opportunity for immediate intraoperative assessment of final screw position giving the option of immediate screw revision if necessary. Thus, postoperative imaging and a potential revision surgery for screw correction become dispensable.Different concept of spinal robotics as the DaVinci system and SpineAssist are under investigation.

Percutaneous dorsal root ganglion lysis with phenol for the treatment of pain associated with thoracic compression fracture

BACKGROUND

Symptomatic thoracic compression fracture is one of the most common causes of back pain in elderly. Although vertebroplasty is widely utilized in patients when conservative treatment fails, we introduced an alternative percutaneous technique for the treatment of thoracic compression pain.

METHODS

This in a retrospective study. The analysis was performed on 28 consecutive patients who underwent undergoing percutaneous dorsal root ganglion lysis with phenol for the treatment of pain associated with thoracic compression fracture. An acceptable treatment outcome was operationally defined as a pain intensity numerical rating scale (NRS) score of 3 or lower or EQ-5D index of 0.672 or higher. The primary outcome was pain relief and acceptable treatment outcome at 1 day, 1 week, 1 month, and 1 year.

RESULTS

Of the 28 cases treated with our procedures, the change in mean NRS score between baseline and one day was -2.5 (95 % CI -1.6 ~ -3.4, p < 0.001), between baseline and one week was -4.7 (-4.1 to -5.3, p < 0.001), between baseline and one month was -5.8 (-5.2 to -6.5, p < 0.001), and between baseline and one year was -6.3 (-5.6 to -7.1, p < 0.001). An acceptable treatment outcome was 14 % one day after the procedure, 46 % at one week, 72 % at one month, and 84 % at one year. Complication rate was 3.6 %.

CONCLUSIONS

For thoracic compression fracture patients, percutaneous dorsal root ganglion lysis with phenol is an effective, and safe alternative treatment method worth considering. Pain relief is fast and persists for one year.

Intraoperative cone beam-computed tomography with navigation (O-ARM) versus conventional fluoroscopy (C-ARM): a cadaveric study comparing accuracy, efficiency, and safety for spinal instrumentation

STUDY DESIGN

Cadaveric laboratory study.

OBJECTIVE

To compare the accuracy, efficiency, and safety of intraoperative cone beam-computed tomography with navigation (O-ARM) with traditional intraoperative fluoroscopy (C-ARM) for the placement of pedicle screws.

SUMMARY OF BACKGROUND DATA

Radiation exposure remains a concern with traditional methods of intraoperative imaging in spine surgery. The use of O-ARM has been proposed for more accurate and efficient spinal instrumentation. Understanding radiation imparted to patients and surgeons by O-ARM is important for assessing risks and benefits of this technology, especially in light of evolving indications.

METHODS

Four surgeons placed 160 pedicle screws on 8 cadavers without deformity. Eighty pedicle screws were placed using O-ARM and C-ARM each. Instrumentation was placed bilaterally in the thoracic (T1-T6) spine and lumbosacral junction (L5-S1) using a standard open technique, whereas minimally invasive surgery technique was used at the lumbar 3 to 4 (L3-L4) level. A "postoperative" computed tomography (CT) scan was performed on cadavers where instrumentation was done using the C-ARM. An independent musculoskeletal radiologist assessed final images for screw position. Time required to set up and instrumentation was recorded. Dosimeters were placed on multiple aspects of cadavers and surgeons to record radiation exposure.

RESULTS

There were no differences in breach rate between the O-ARM and C-ARM groups (5 vs. 7, χ= 0.63, P = 0.4). The setup time for the O-ARM group was longer than that for the C-ARM group (592 vs. 297 s, P < 0.05). However, the average total time was statistically the same (1629 vs. 1639 s, P = 0.96). Radiation exposure was higher for surgeons in the C-ARM group and cadavers in the O-ARM group. When a "postoperative" CT scan was included in the estimation of the total radiation exposure, there was less of difference between the groups, but still more for the O-ARM group.

CONCLUSION

In cadavers without deformity, O-ARM use results in similar breach rates as C-ARM for the placement of pedicle screws. Time for instrumentation is shorter with the O-ARM, but requires a longer setup time. The O-ARM exposes less radiation to the surgeon, but higher doses to the cadaver.

LEVEL OF EVIDENCE

N/A.

Routine spinal navigation for thoraco-lumbar pedicle screw insertion using the O-arm three-dimensional imaging system improves placement accuracy

Modern image-guided spinal navigation employs high-quality intra-operative three dimensional (3D) images to improve the accuracy of spinal surgery. This study aimed to assess the accuracy of thoraco-lumbar pedicle screw insertion using the O-arm (Breakaway Imaging, LLC, Littleton, MA, USA) 3D imaging system. Ninety-two patients underwent insertion of thoraco-lumbar pedicle screws guided by O-arm navigation over a 27 month period. Intra-operative scans were retrospectively reviewed for pedicle breach. The operative time of patients where O-arm navigation was used was compared to a matched control group where fluoroscopy was used. A total of 467 pedicle screws were inserted. Four hundred and forty-five screws (95.3%) were placed within the pedicle without any breach (Gertzbein classification grade 0). Sixteen screws (3.4%) had a pedicle breach of less than 2mm (Gertzbein classification grade 1), and six screws (1.3%) had a pedicle breach between 2mm and 4mm (Gertzbein classification grade 2). The grade 2 screws were revised intra-operatively. There was no incidence of neurovascular injury in this series of patients. The mean operative time for O-arm patients was 5.25 hours. In a matched control group of fluoroscopy patients, the mean operative time was 4.75 hours. The difference in the mean operative time between the two groups was not statistically significant (p=0.15, paired t-test). Stereotactic navigation based on intra-operative O-arm 3D imaging resulted in high accuracy in thoraco-lumbar pedicle screw insertion.

Surgical treatment of adult and pediatric C1/C2 subluxation with intraoperative computed tomography guidance

BACKGROUND

Surgical treatment of C1/C2 subluxation has evolved significantly over the past 2 decades, from the relatively simpler posterior wiring to more technically demanding instrumentations such as C1 lateral mass screws - C2 pedicle screws, C1/C2 transarticular screws, and occipital cervical fusion. Navigation with fluoroscopy is currently the standard of practice in most centers. However, fluoroscopy at this level carries several major drawbacks, such as blockage by the mandible and inability to produce axial images for assessment of the reduction of rotatory subluxation.

METHODS

The authors report a series of 21 patients with C1/C2 subluxation treated surgically with intraoperative computed tomography (ICT) guidance.

RESULTS

There were 7 children and 14 adults. Eight patients underwent C1/C2 fixation with a Harm's construct, and 13 patients underwent occipital cervical fusion. One out of 17 (6%) C1 lateral mass screws has breached the medial wall of lateral mass by 1 mm. Two out of 20 (10%) C2 pedicle screws have breached the foramen transversarium by 1 mm (Neo classification grade 1). The position of all subaxial screws (49 lateral mass screws and 13 pedicle screws) and occipital screws (50 screws) appeared satisfactory. No neurovascular damage occurred in all the patients.

CONCLUSIONS

Ninety eight percent of the screws were placed in ideal position with the aid of ICT. Only 2% of the screws deviated from the planned position, but the breaches were not clinically significant and hence no revision was required. This showed that ICT guidance can help to achieve a high accuracy of surgical instrumentation for the treatment of C1/C2 subluxation.

Navigated guide tube for the placement of mini-open pedicle screws using stereotactic 3D navigation without the use of K-wires

Object

Three-dimensional spinal navigation increases screw accuracy, but its implementation in clinical practice has been difficult, mainly because of surgeons' concerns about increased operative times, disturbance of workflow, and safety. The authors present a custom-designed navigated guide that addresses some of these concerns by allowing for drilling, tapping, and placing the final screw via a minimally invasive approach without the need for K-wires. In this paper, the authors' goal was to describe the technical aspects of the navigated guide tube as well as pedicle screw accuracy.

Methods

The authors present the technical details of a navigated guide that allows drilling, tapping, and the placement of the final screw without the need for K-wires. The first 10 patients who received minimally invasive mini-open spinal pedicle screws are presented. The case series focuses on the immediate postoperative outcomes, pedicle screw accuracy, and pedicle screw–related complications. An independent board-certified neuroradiologist determined pedicle screw accuracy according to a 4-tiered grading system.

Results

The navigated guide allowed successful placement of mini-open pedicle screws as part of posterior fixation from L-1 to S-1 without the use of K-wires. Only 7-mm-diameter screws were placed, and 72% of screws were completely contained within the pedicle. Breaches less than 2 mm were seen in 23% of cases, and these were all lateral except for one screw. Breaches were related to the lateral to medial trajectory chosen to avoid the superior facet joint. There were no complications related to pedicle screw insertion.

Conclusions

A novel customized navigated guide tube is presented that facilitates the workflow and allows accurate placement of mini-open pedicle screws without the need for K-wires.

Intra-operative cone-beam CT (O-arm) and stereotactic navigation in acute spinal trauma surgery

The purpose of this ambispective cohort study is to describe the emerging role of intra-operative cone-beam CT (O-arm®, Medtronic, Minneapolis, MN, USA), frequently coupled with stereotactic navigation (StealthStation®, Medtronic), in the surgical management of acute spinal trauma. All patients with acute spinal trauma between May 2009 and May 2011 who were treated with the use of the O-arm were identified from a prospectively collected spine database and retrospectively analyzed to characterize indications and outcomes. Over the two-year period, the O-arm was used in 183 spinal operations; 27 of these (15%) involved acute spinal trauma. Within the trauma cohort, 14 injuries were in the cervical spine, nine at the cervicothoracic junction, and four were in the thoracolumbar spine. In 12 patients (44%) pre-existing aberrant and challenging anatomy, commonly ankylosing conditions, were present. Surgical techniques included transarticular atlantoaxial fixation and direct osteosynthesis of a Hangman's fracture performed entirely percutaneously (via two stab incisions) using O-arm assisted stereotactic navigation. No trauma cases using O-arm assisted navigation had iatrogenic neurovascular injury and none required subsequent revision surgery for implant malposition, compared with a revision rate of 1.2% of patients with non-navigated acute spinal trauma during the same interval. Technical factors associated with successful application of this technology in the setting of acute spinal trauma were detailed. O-arm assisted navigation can overcome anatomical challenges and broaden the available stabilization options in the management of acute spinal trauma. Other advantages include protecting the surgical team from cumulative fluoroscopic radiation exposure and patients from repeat surgery due to implant malposition.