Computer-assisted posterior instrumentation of the cervical and cervico-thoracic spine

Free-hand technique of C7 pedicle screw insertion using a simply defined entry point without fluoroscopic guidance for cervical spondylotic myelopathy patients with C3 to C6 instrumented by lateral mass screws: a retrospective cohort study

BACKGROUND

Nowadays, both lateral mass screw (LMS) and pedicle screw were effective instrumentation for posterior stabilization of cervical spine. This study aims to evaluate the feasibility of a new free-hand technique of C7 pedicle screw insertion without fluoroscopic guidance for cervical spondylotic myelopathy (CSM) patients with C3 to C6 instrumented by lateral mass screws.

METHODS

A total of 53 CSM patients underwent lateral mass screws instrumentation at C3 to C6 levels and pedicle screw instrumentation at C7 level were included. The preoperative 3-dimenional computed tomography (CT) reconstruction images of cervical spine were used to determine 2 different C7 pedicle screw trajectories. Trajectory A passed through the axis of the C7 pedicle while trajectory B selected the midpoint of the base of C7 superior facet as the entry point. All these 53 patients had the C7 pedicle screw inserted through trajectory B by free-hand without fluoroscopic guidance and the postoperative CT images were obtained to evaluate the accuracy of C7 pedicle screw insertion.

RESULTS

Trajectory B had smaller transverse angle, smaller screw length, and smaller screw width but both similar sagittal angle and similar pedicle height when compared with trajectory A. A total of 106 pedicle screws were inserted at C7 through trajectory B and only 8 screws were displaced with the accuracy of screw placement as high as 92.5%.

CONCLUSION

In CSM patients with C3 to C6 instrumented by LMS, using trajectory B for C7 pedicle screw insertion is easy to both identify the entry point and facilitate the rod insertion.

[Spinal navigation with preoperative computed tomography]

OBJECTIVE

Safe placement of posterior cervical-sacral pedicle screws, S2-Ala-iliac screws, iliac screws, transarticular screws C1/2, translaminar screws C2 or cervical lateral mass screws under the guidance of spinal navigation.

INDICATIONS

All posterior spinal instrumentations with screws: instabilities and deformities of rheumatic, traumatic, neoplastic, infectious, iatrogenic or congenital origin; multilevel cervical spinal stenosis with degenerative instability or kyphosis of the affected spinal segment.

CONTRAINDICATIONS

There are no absolute contraindications for spinal navigation.

SURGICAL TECHNIQUE

Cervical spine: Prone position on a gel mattress, rigid head fixation, e.g., with Mayfield tongs; if appropriate, closed reduction under lateral image intensification; thoracic + lumbar spine: prone position on a cushioned frame; midline posterior surgical approach at the level of the segments to be instrumented; if necessary, open reduction; insertion of the cervical/upper thoracic screws under the guidance of spinal navigation; if necessary, posterior decompression; instrumentation longitudinal rods; if fusion is to be obtained, decortication of the posterior bone elements with a high-speed burr and onlay of cancellous bone or bone substitutes.

POSTOPERATIVE MANAGEMENT

In stable instrumentations, no postoperative immobilization with orthosis is necessary, removal of drains (if used) 2-3 days postoperatively (postop), removal of the sutures 14 days postop, clinical and x‑ray controls 3 and 12 months postop or in case of clinical or neurological deterioration.

RESULTS

Numerous studies showed that the use of spinal navigation significantly reduces implant malplacement rates, complications, and revision surgery. Furthermore, intraoperative radiation exposure to the operation team can be reduced by up to 90%.

Robotic-guided placement of cervical pedicle screws: feasibility and accuracy

INTRODUCTION

It has been shown that pedicle screw instrumentation in the cervical spine has superior biomechanical pullout strength and stability. However, due to the complex and variable anatomy of the cervical pedicles and the risk of catastrophic complications, cervical pedicle screw placement is not widely utilized.

STUDY DESIGN

A retrospective, consecutive patient review.

OBJECTIVE

To review and report our experience with robotic guided cervical pedicle screw placement.

METHODS

We retrospectively reviewed preoperative and postoperative CT scans of 12 consecutive patients who underwent cervical pedicle screw fixation with robotic guidance. Screw placement and deviation from the preoperative plan were assessed using the robotic system's planning software by fusing the preoperative CT (with the planned cervical pedicle screws) to the post-op CT. This process was carried out by manually aligning the anatomical landmarks on the two CTs. Once a satisfactory fusion was achieved, the software's measurement tool was used manually to compare the planned vs. actual screw placements in the axial, sagittal and coronal planes within the instrumented pedicle in a resolution of 0.1 mm. Medical charts were reviewed for technical issues and intra-operative complications.

RESULTS

Eighty-eight cervical pedicle screws were reviewed in 12 patients; mean age = 65 years, M:F = 2:1, and mean BMI = 27.99. No intra-operative complications related to the cervical pedicle screw placement were reported. Robotic guidance was successful in all 88 screws: eight in C2, 14 in C3, 16 in each of C4 and C5, 19 in C6, and 15 at C7. There were 14 pedicle screw breaches (15.9%); all were medial, less than 1 mm, and with no clinical consequences. In the axial plane, the screws deviated from the preoperative plan by 1.32 ± 1.17 mm and in the sagittal plane by 1.27 ± 1.00 mm. In the trajectory view, the overall deviation was 2.20 ± 1.17 mm. Although differences were observed in screw deviation from the pre-op plan between the right and left sides, they were not statistically significant (p > 0.05).

CONCLUSION

This study indicates that robotic-guided cervical pedicle screw placement is feasible and safe. The medial breaches did not result in any clinical consequences.

Workflow and performance of intraoperative CT, cone-beam CT, and robotic cone-beam CT for spinal navigation in 503 consecutive patients

OBJECTIVE

A direct comparison of intraoperative CT (iCT), cone-beam CT (CBCT), and robotic cone-beam CT (rCBCT) has been necessary to identify the ideal imaging solution for each individual user's need. Herein, the authors sought to analyze workflow, handling, and performance of iCT, CBCT, and rCBCT imaging for navigated pedicle screw instrumentation across the entire spine performed within the same surgical environment by the same group of surgeons.

METHODS

Between 2014 and 2018, 503 consecutive patients received 2673 navigated pedicle screws using iCT (n = 1219), CBCT (n = 646), or rCBCT (n = 808) imaging during the first 24 months after the acquisition of each modality. Clinical and demographic data, workflow, handling, and screw assessment and accuracy were analyzed.

RESULTS

Intraoperative CT showed image quality and workflow advantages for cervicothoracic cases, obese patients, and long-segment instrumentation, whereas CBCT and rCBCT offered independent handling, around-the-clock availability, and the option of performing 2D fluoroscopy. All modalities permitted reliable intraoperative screw assessment. Navigated screw revision was possible with each modality and yielded final accuracy rates > 92% in all groups (iCT 96.2% vs CBCT 92.3%, p < 0.001) without a difference in the accuracy of cervical pedicle screw placement or the rate of secondary screw revision surgeries.

CONCLUSIONS

Continuous training and an individual setup of iCT, CBCT, and rCBCT has been shown to permit safe and precise navigated posterior instrumentation across the entire spine with reliable screw assessment and the option of immediate revision. The perceived higher image quality and larger scan area of iCT should be weighed against the around-the-clock availability of CBCT and rCBCT technology with the option of single-handed robotic image acquisition.

Iatrogenic Vascular Injury Associated with Cervical Spine Surgery: A Systematic Literature Review

BACKGROUND

Iatrogenic vascular injury is an uncommon complication of anterior and/or posterior surgical approaches to the cervical spine. Although the results of this injury may be life-threatening, mortality/morbidity can be reduced by an understanding of its mechanism and proper management.

METHODS

We conducted a literature review to provide an update of this devastating complication in spine surgery. A total of 72 articles including 194 cases of vascular lesions following cervical spine surgery between 1962 and 2021 were analyzed.

RESULTS

There were 53 female and 41 male cases (in addition to 100 cases with unreported sex) with ages ranging from 3 to 86 years. The vascular injuries were classified according to the spinal procedures, such as anterior or posterior cervical spine surgery. The interval between the symptom of the vascular injury and the surgical procedure ranged from 0 to 10 years. Only two-thirds of patients underwent intra- or postoperative imaging and the most frequently injured vessel was the vertebral artery (86.60%). Laceration was the most common lesion (41.24%), followed by pseudoaneurysm (16.49%) and dissection (5.67%). Vascular repair was performed in 114 patients. The mortality rate was 7.22%, and 18.04% of patients had 1 or more other complications. Most presumed causes of vascular lesions were by instrumentation/screw placement (31.44%) or drilling (20.61%). Sixteen patients had an anomalous artery. Direct microsurgical repair was achieved in only 15 cases.

CONCLUSIONS

Despite increased anatomical knowledge and advanced imaging techniques, we need to consider the risk of vascular injury as a surgical complication in patients with cervical spine pathologies.

Cervical Spine Pedicle Screw Accuracy in Fluoroscopic, Navigated and Template Guided Systems-A Systematic Review

Background: Pedicle screws provide excellent fixation for a wide range of indications. However, their adoption in the cervical spine has been slower than in the thoracic and lumbar spine, which is largely due to the smaller pedicle sizes and the proximity to the neurovascular structures in the neck. In recent years, technology has been developed to improve the accuracy and thereby the safety of cervical pedicle screw placement over traditional fluoroscopic techniques, including intraoperative 3D navigation, computer-assisted Systems and 3D template moulds. We have performed a systematic review into the accuracy rates of the various systems. Methods: The PubMed and Cochrane Library databases were searched for eligible papers; 9 valid papers involving 1427 screws were found. Results: fluoroscopic methods achieved an 80.6% accuracy and navigation methods produced 91.4% and 96.7% accuracy for templates. Conclusion: Navigation methods are significantly more accurate than fluoroscopy, they reduce radiation exposure to the surgical team, and improvements in technology are speeding up operating times. Significantly superior results for templates over fluoroscopy and navigation are complemented by reduced radiation exposure to patient and surgeon; however, the technology requires a more invasive approach, prolonged pre-operative planning and the development of an infrastructure to allow for their rapid production and delivery. We affirm the superiority of navigation over other methods for providing the most accurate and the safest cervical pedicle screw instrumentation, as it is more accurate than fluoroscopy and lacks the limitations of templates.

[Guideline-conform treatment of injuries to the subaxial cervical spine]

Injuries to the subaxial cervical spine are increasing and have an increased neurological risk compared to the thoracic and lumbar spines. The current treatment recommendations according to the therapeutic recommendations of the Spine Section of the German Society for Orthopedics and Trauma Surgery (DGOU) as well as the S1 guidelines of the German Trauma Society (DGU) are presented. This second part of the article describes the correct indications and treatment planning for injuries to the cervical spine. Based on the AOSpine classification for subaxial cervical spine injuries, decisions can be made about conservative or surgical treatment as well as individual details of the treatment. The underlying principles of treatment are relief of neurological structures, restoration of stability and reconstruction/preservation of the physiological alignment.

Clinical efficiency of operating room-based sliding gantry CT as compared to mobile cone-beam CT-based navigated pedicle screw placement in 853 patients and 6733 screws

PURPOSE

Multiple solutions for navigation-guided pedicle screw placement are available. However, the efficiency with regard to clinical and resource implications has not yet been analyzed. The present study's aim was to analyze whether an operating room sliding gantry CT (ORCT)-based approach for spinal instrumentation is more efficient than a mobile cone-beam CT (CBCT)-based approach.

METHODS

This cohort study included a random sample of 853 patients who underwent spinal instrumentation using ORCT-based or CBCT-based pedicle screw placement due to tumor, degenerative, trauma, infection, or deformity disorders between November 2015 and January 2020.

RESULTS

More screws had to be revised intraoperatively in the CBCT group due to insufficient placement (ORCT: 98, 2.8% vs. CBCT: 128, 4.0%; p = 0.0081). The mean time of patients inside the OR (Interval 5 Entry-Exit) was significantly shorter for the ORCT group (ORCT: mean, [95% CI] 256.0, [247.8, 264.3] min, CBCT: 283.0, [274.4, 291.5] min; p < 0.0001) based on shorter times for Interval 2 Positioning-Incision (ORCT: 18.8, [18.1, 19.9] min, CBCT: 33.6, [32.2, 35.5] min; p < 0.0001) and Interval 4 Suture-Exit (ORCT: 24.3, [23.6, 26.1] min, CBCT: 29.3, [27.5, 30.7] min; p < 0.0001).

CONCLUSIONS

The choice of imaging technology for navigated pedicle screw placement has significant impact on standard spine procedures even in a high-volume spine center with daily routine in such devices. Particularly with regard to the duration of surgeries, the shorter time needed for preparation and de-positioning in the ORCT group made the main difference, while the accuracy was even higher for the ORCT.

Navigation for surgical treatment of disorders of the cervical spine - A systematic review

INTRODUCTION

Computer-assisted navigation (CAN) is a well-established tool in spinal instrumentation surgery. Different techniques - each with specific advantages and disadvantages - are used in the cervical spine.

METHODS

A structured summary of different spinal navigation techniques and a review of the literature were done to discuss the advantages and disadvantages of specific navigation tools in the cervical spine.

RESULTS

In cervical spine surgery, CAN increases the accuracy of pedicle screw placement, reduces screw mispositioning and leads to fewer revision surgeries. Due to the mobility of the cervical spine, preoperative CT followed by region matching or intraoperative CT are recommended.

CONCLUSIONS

CAN increases pedicle screw placement accuracy and should be used in spinal instrumentation for the cervical spine whenever possible.

Assessing the Clinical Safety Profile of Computer-Assisted Navigation for Posterior Cervical Fusion: A Propensity-Matched Analysis of 30-Day Outcomes

BACKGROUND

Computer-assisted navigation (CAN) has been shown to improve accuracy of screw placement in procedures involving the posterior cervical spine, but whether the addition of CAN affects complication rates, neurologic or otherwise, is presently unknown. The objective of this study is to determine the effect of spinal CAN on short-term clinical outcomes following posterior cervical fusion.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database was queried from 2011 to 2018. Patients receiving posterior cervical fusion were identified and separated into CAN and non-CAN cohorts on the basis of a propensity score matching algorithm to select similar patients for comparison. Rates of 30-day unplanned readmission, reoperation, and other complications were evaluated. A separate matching algorithm was used to generate a subgroup of patients undergoing C1-C2 or occiput-C2 fusion for comparison of the same outcomes.

RESULTS

A total of 12,578 patients met inclusion criteria, of which 689 received CAN and 11,889 did not. After adjusting for baseline differences, patients receiving CAN experienced longer operations and had higher total relative value units associated with care. There were no significant differences in 30-day complication, readmission, or revision rates. At the occipitocervical junction, there were more hardware revisions in the non-CAN group, but this effect did not reach statistical significance (2 vs. 0; P = 0.155).

CONCLUSIONS

Surgeons should embrace navigation in the cervical spine at their own discretion, as use of CAN does not appear to be associated with increased rates of surgical complications or readmissions despite longer operative time.

Investigation of the Effects of Three-Dimensional Modeling Techniques on Degenerative Rotoscoliosis Surgery

Objectives

The present study aimed to compare patients in whom an operation plan was prepared before surgery using the three-dimensional (3D) modeling technology with the application of freehand screws using magnetic resonance imaging (MRI) and computed tomography (CT) scan images.

Methods

The printings and modelings were established in the Training and Research Center. Of 40 patients, 20 underwent surgery with 3D printing (Group 1) and 20 with the freehand technique (Group 2). The surgeries were performed by the same surgeons. Moreover, 5-mm pedicle screws were located in 122 vertebrae in 20 patients in whom 3D modeling was used and in 124 vertebrae in 20 patients in whom this modeling technique was not used.

Results

The mean time of screw insertion was 2.9 ± 1.2 minutes in the experimental group and 4.7 ± 2.3 minutes in the control group. While the mean amount of bleeding was 7.4 ± 4.1 ml in the experimental group, it was found to be 39.6 ± 14.2 ml in the control group. When the locations of the screws in the experimental group were evaluated, it was seen that 106 (86.9%) screws were ‘excellent’ and 16 (13.1%) screws were ‘good.’ When the placement of 124 pedicle screws in the control group was evaluated, it was found that 100 (80.6%) screws were ‘excellent,’ 20 (17.8%) screws were ‘good,’ and two (1.6%) screws were ‘poor.’

Conclusion

The use of the improved 3D technology in the neurosurgery field is advantageous for surgeons, as it decreases the preoperative preparation phase, length of operation, and risk of complications.

Safety and Feasibility of Cervical Pedicle Screw Insertion in Pediatric Subaxial Cervical Spine Without Navigation: A Retrospective Cohort Study

BACKGROUND

The use of cervical pedicle screws (CPSs) in pediatric subaxial cervical spine has been scarcely reported in the literature. The biomechanical superiority of CPS over other methods of fixation is beneficial in surgery for correcting severe, rigid cervical/cervicothoracic deformity. Our study aims to assess the safety, efficacy, and feasibility of CPS fixation in pediatric subaxial cervical spine without intraoperative navigation.

METHODS

Eight pediatric patients requiring rigid subaxial cervical spine fixation for complex cervical deformities were operated at a single center between 2014 and 2016. Their hospital records and imaging were retrospectively studied. The feasibility of inserting CPS was assessed by studying pedicle morphometry on preoperative computed tomography (CT) scans. Aberrant vertebral artery anatomy was ruled out using CT angiography. CPS were inserted into selected pedicles without navigation. Postoperative CT scans were studied to look for screw containment within pedicles. Complications were noted and clinicoradiologic follow-up was for a minimum of 36 months.

RESULTS

Thirty-seven CPS were inserted in 8 pediatric patients with a mean age of 9.2 years (range: 5 to 13 y). Surgery was done for complex cervical deformities due to various causes-neglected cervical spine trauma (n=3), posttubercular kyphosis (n=2), cervicothoracic scoliosis (n=2), and cervicothoracic osteoblastoma (n=1). The level-wise distribution of the inserted CPS was: C3=4, C4=6, C5=10, C6=10, and C7=7. Postoperative CT scans showed grade-1 medial cortical breach in 5/37 screws and grade-2 medial cortical breach in a single screw (16%). No perioperative complications were noted. At a mean follow-up of 3.6 years (range: 3 to 4.33 y), no patient had implant failure or deformity progression.

CONCLUSIONS

CPS insertion in pediatric subaxial cervical spine without neuronavigation is safe, feasible, and effective in carefully selected cases. Biomechanical advantages of CPS can be extended to the pediatric subaxial cervical spine.

LEVEL OF EVIDENCE

Level IV-retrospective cohort.

[Relevance of spinal navigation in reconstructive surgery of the cervical spine]

BACKGROUND

Spinal navigation has made significant advances in the last two decades. After initial experiences with pedicle screws in the thoracic and lumbar spine, technological improvements have resulted in their increased application in the cervical spine. Instrumentation techniques like cervical pedicle screws, lateral mass screws in C1 and transarticular screws C1/C2 have become standard due to the application of image guidance.

TECHNIQUE

Different navigation techniques can be distinguished based on the type of imaging. In the cervical spine, the preoperative computer tomography (CT) scan that requires intraoperative matching is still the standard of care due to the high image quality. 3D fluoroscopy navigation techniques are currently widely used in the lumbar spine, but the reduced image quality obviates the application in the more sophisticated cervical anatomy or the cervicothoracic region. The future availability of intraoperative CT scans (iCT) combines the advantages of high image quality with those of intraoperative image acquisition. This will lead to a wider use of image guidance in the cervical spine and will enable the surgeon to apply minimally invasive techniques with higher accuracy.

APPLICATION

The successful application of spinal navigation is based on the technical knowledge of navigation systems and its exercise in daily routine. Only the sufficient experience of the clinical staff makes it possible to standardize operational procedures to increase patient safety, reduce radiation dose and shorten operation time.

[Spinal navigation for posterior cervical and cervicothoracic instrumentation]

OBJECTIVE

Safe placement of posterior cervical or high-thoracic pedicle screws, transarticular screws C1/2, translaminar screws C2 or cervical lateral mass screws under the guidance of spinal navigation.

INDICATIONS

All posterior cervical and cervicothoracic instrumentation with screws: instabilities and deformities of rheumatoid, traumatic, neoplastic, infectious, iatrogenic or congenital origin; multilevel cervical spinal stenosis with degenerative instability or kyphosis of the affected spinal segment.

CONTRAINDICATIONS

There are no absolute contraindications.

SURGICAL TECHNIQUE

Prone position on a gel mattress, rigid head fixation, e.g., with Mayfield tongs; if appropriate, closed reduction under lateral image intensification; midline posterior surgical approach at the level of the segments to be instrumented; if necessary, open reduction; insertion of the cervical/upper thoracic screws under the guidance of spinal navigation; if necessary, posterior decompression; instrumentation longitudinal rods; if a fusion is to be obtained, decortication of the posterior bone elements with a high-speed burr and onlay of cancellous bone or bone substitutes.

POSTOPERATIVE MANAGEMENT

In stable instrumentation, no postoperative immobilization with cervical collar is necessary. Drain removal on postoperative day 2-3, suture removal on postoperative day 14, clinical and x‑ray control 3 and 12 months after surgery or in case of clinical or neurological deterioration.

RESULTS

Numerous studies showed that the use of spinal navigation reduces implant malplacement rates significantly. Furthermore, it allows a reduction of the radiation dose for the operation team up to 90%.

Three-dimensional navigation (O-arm) versus fluoroscopy in the treatment of thoracic spinal stenosis with ultrasonic bone curette: A retrospective comparative study

Three-dimensional intraoperative navigation (O-arm) has been used for many years in spinal surgeries and has significantly improved its precision and safety. This retrospective study compared the efficacy and safety of spinal cord decompression surgeries performed with O-arm navigation and fluoroscopy. The clinical data of 56 patients with thoracic spinal stenosis treated from March 2015 to April 2017 were retrospectively analyzed. Spinal decompression was performed with O-arm navigation and ultrasonic bone curette in 29 patients, and with ultrasonic bone curette and fluoroscopy in 27 patients. Patients were followed-up at postoperative 1 month, 3 months, and the last clinic visit. The neurologic functions were assessed using the Japanese Orthopaedic Association (JOA) Back Pain Evaluation Questionnaire. The accuracy of screw placement was examined using three-dimensional computed tomography (CT) on postoperative day 5. There was no significant difference in the incidences of intraoperative dural tear, nerve root injury, and spinal cord injury between the two groups. The two groups showed no significant difference in postoperative JOA scores (P > .05). The O-arm navigation group had significantly higher screw placement accuracy than the fluoroscopy group (P < .05). O-arm navigation is superior to fluoroscopy in the treatment of thoracic spinal stenosis with ultrasonic bone curette in terms of screw placement accuracy. However, the two surgical modes have similar rates of intraoperative complications and postoperative neurologic functions.

A Review of the Historical Evolution, Biomechanical Advantage, Clinical Applications, and Safe Insertion Techniques of Cervical Pedicle Screw Fixation

Cervical spine instrumentation is evolving with an aim of stabilizing traumatic and non-traumatic cases of the cervical spine with a beneficial reduction, better biomechanical strength, and a strong construct with minimal intraoperative, as well as immediate and late postoperative complications. The evolution from interspinous wiring till cervical pedicle screws has changed the outlook in treating the cervical spine pathologies with maximum 3D stability, decreasing the duration of postoperative immobilization and hospital stay. Some complications associated with the use of cervical pedicle screw can be catastrophic. This review article discusses the morphometry of cervical pedicle; indications, biomechanical superiority, tricks, and pitfalls of cervical pedicle screw; complications and technical advancements in targeting safe surgery; and future directions of cervical pedicle screw instrumentation.

Posterior Transpedicular Screw Fixation of Subaxial Vertebrae: Accuracy Rates and Safety of Mini-laminotomy Technique

Background and Aim:

Posterior cervical transpedicular screw fixation has the strongest resistance to pullout forces compared with other posterior fixation systems. Here, we present a case on the use of this technique combined with a mini-laminotomy technique, which serves as a guide for accurate insertion of posterior cervical transpedicular screws.

Materials and Methods:

We retrospectively analyzed data from 40 patients who underwent this procedure in our clinic between January 2014 and March 2017.

Results:

The study population comprised 27 males (67.5%) and 13 females (32.5%) aged 15–80 years (median, 51.5 years). Surgical indications included trauma (n = 18, 45%), degenerative disease (n = 19, 47.5%), spinal infection (n = 2, 5%), and basilar invagination due to systemic rheumatoid disease (n = 1, 2.5%). In the 18 trauma patients, 14 short-segment (1–2 levels) and 4 long-segment (≥3 levels) posterior cervical instrumentation and fusion procedures were performed. The mini-laminotomy technique was used in all patients to insert, direct, and achieve exact screw fixation in the pedicles. Pedicle perforations were classified as medial or lateral and were also graded. Among the 227 cervical pedicle fixations performed, 48 were at the C3 level, 49 at C4, 60 at C5, 50 at C6, and 20 at C7. Axial computed tomography scan measurements showed that 205 of 227 (90.3%, Grade 0 and 1) screws were accurately placed, whereas 22 (9.69%, Grade 2 and 3) were misplaced. However, no additional neurological injury due to misplacement was observed.

Conclusion:

As negligible complications were observed when performed by experienced surgeons, the mini-laminotomy technique can be safely used for posterior transpedicular screw fixation in the subaxial vertebrae for single-staged fusion.

Potential intraoperative factors of screw-related complications following posterior transarticular C1-C2 fixation: a systematic review and meta-analysis

PURPOSE

This study aimed to evaluate the impact of several factors, including patients' intraoperative position, intraoperative visualization technique, fixation method, and type of screws and their parameters, on the frequency of intraoperative screw-associated complications in posterior transarticular C1-C2 fixation.

METHODS

A systematic review of the PubMed database between January 1986 and March 2018 was performed. The key inclusion criteria comprised detailed descriptions of the surgical technique and post-operative screw-associated complications.

RESULTS

The initial search resulted in 1041 abstracts, and a total of 54 abstracts were included in the present study. The overall number of operated patients was 2306. In this group, 4439 screws were inserted. The rate of screw-associated complications during the different time periods was estimated upon meta-analysis. Statistical analysis of the screw malposition rate, vertebral artery injury rate, screw breakage rate based on patients' intraoperative position, intraoperative visualization technique, fixation method, and type of implants and their parameters was also performed.

CONCLUSIONS

The factors that help reduce the rate of screw-associated complications include the intraoperative application of biplanar fluoroscopy or neuronavigation system, the use of 4 mm or thicker lag screws, and screw insertion through contraincisions using cannulated ported instruments. On the other hand, the potential risk factors of screw-associated complications include inadequate intraoperative head fixation using skeletal traction, uniplanar fluoroscopy-guided screw insertion, screw insertion using the posterior midline approach, and the use of 3.5 mm or thinner full-threaded screws. These slides can be retrieved under Electronic Supplementary Material.

Does pedicle screw fixation of the subaxial cervical spine provide adequate stabilization in a multilevel vertebral body fracture model? An in vitro biomechanical study

BACKGROUND

Cervical vertebral body fractures generally are treated through an anterior-posterior approach. Cervical pedicle screws offer an alternative to circumferential fixation. This biomechanical study quantifies whether cervical pedicle screws alone can restore the stability of a three-column vertebral body fracture, making standard 360° reconstruction unnecessary.

METHODS

Range of motion (2.0 Nm) in flexion-extension, lateral bending, and axial rotation was tested on 10 cadaveric specimens (five/group) at C2-T1 with a spine kinematics simulator. Specimens were tested for flexibility of intact when a fatigue protocol with instrumentation was used to evaluate construct longevity. For a C4-6 fracture, spines were instrumented with 360° reconstruction (corpectomy spacer + plate + lateral mass screws) (Group 1) or cervical pedicle screw reconstruction (C3 and C7 only) (Group 2).

FINDINGS

Results are expressed as percentage of intact (100%). In Group 1, 360° reconstruction resulted in decreased motion during flexion-extension, lateral bending, and axial rotation, to 21.5%, 14.1%, and 48.6%, respectively, following 18,000 cycles of flexion-extension testing. In Group 2, cervical pedicle screw reconstruction led to reduced motion after cyclic flexion-extension testing, to 38.4%, 12.3%, and 51.1% during flexion-extension, lateral bending, and axial rotation, respectively.

INTERPRETATION

The 360° stabilization procedure provided the greatest initial stability. Cervical pedicle screw reconstruction resulted in less change in motion following cyclic loading with less variation from specimen to specimen, possibly caused by loosening of the shorter lateral mass screws. Cervical pedicle screw stabilization may be a viable alternative to 360° reconstruction for restoring multilevel vertebral body fracture.

Intraoperative Computed Tomography Versus 3D C-Arm Imaging for Navigated Spinal Instrumentation

STUDY DESIGN

A prospective case-series study and a retrospective analysis of historical patients for comparison of data.

OBJECTIVE

To compare accuracy and limitations of intraoperative computed tomography (iCT)- versus 3D C-arm-based spinal navigation for posterior pedicle screw implantation.

SUMMARY OF BACKGROUND DATA

Despite the higher accuracy of navigated compared to non-navigated pedicle screw implantation, it remains a matter of debate whether the use of iCT imaging may further benefit navigated spinal instrumentation compared to more commonly used isocentric 3D C-arm imaging.

METHODS

Between 2013 and 2016, 1527 pedicle screws were implanted in 260 patients with iCT (1219 screws) or 3D C-arm (308 screws)-based spinal navigation. Screw positioning was intraoperatively assessed by a second iCT or 3D C-arm (intraoperative accuracy). If necessary, immediate intraoperative screw revision was performed. Thereafter, a third iCT or 3D C-arm scan was performed to confirm repositioning (final accuracy). Clinical and patient data, intraoperative screw assessability, and accuracy rates were retrospectively reviewed and analyzed by an independent observer.

RESULTS

Intraoperative CT permitted immediate intraoperative assessment of each implanted screw. In contrast, 39 of the screws visualized with 3D C-arm imaging were intraoperatively not clearly assessable. Regarding the overall precision, iCT and 3D C-arm navigation yielded a comparable intraoperative accuracy (iCT 94.7% vs 3D C-arm 89.4%) and immediate correction of misplaced screws was feasible with both modalities (final accuracy: iCT 95.4% vs 3D C-arm 91.6%). Regarding the region specific performance, however, iCT-based navigation yielded significantly higher final accuracy rates in the cervical (iCT 99.5% vs 3D C-arm 88.9%, P < 0.01) and thoracic (iCT 97.7% vs 3D C-arm 88.8%, P < 0.001) regions.

CONCLUSION

Both iCT and 3D C-arm-based spinal navigation provides high pedicle screw accuracy rates. Immediate screw assessability and placement accuracy in the cervical-thoracic spine, however, appear to be limited with intraoperative 3D C-arm imaging alone.

LEVEL OF EVIDENCE

3.

When does intraoperative 3D-imaging play a role in transpedicular C2 screw placement?

INTRODUCTION

The stabilization of an atlantoaxial (C1-C2) instability is demanding due to a complex atlantoaxial anatomy with proximity to the spinal cord, a variable run of the vertebral artery (VA) and narrow C2 pedicles. We perfomed the Goel & Harms fusion in combination with an intraoperative 3D imaging to ensure correct screw placement in the C2 pedicle. We hypothesized, that narrow C2 pedicles lead to a higher malposition rate of screws by perforation of the pedicle wall. The purpose of this study was to describe a certain pedicle size, under which the perforation rate rises.

PATIENTS AND METHODS

In this retrospective study, all patients (n=30) were operated in the Goel & Harms technique. The isthmus height and pedicle diameter of C2 were measured. The achieved screw position in C2 was evaluated according to Gertzbein & Robbin classification (GRGr).

RESULTS

A statistically significant correlation was found between the pedicles size (isthmus height/pedicle diameter) and the achieved GRGr for the right (p=0.002/p=0.03) and left side (p=0.018/p=0.008). The ROC analysis yielded a Cut Off value for the pedicle size to distinguish between an intact or perforated pedicle wall (GRGr 1 or ≥2). The Cut-Off value was identified for the isthmus height (right 6.1mm, left 5.4mm) and for the pedicle diameter (6.6mm both sides).

CONCLUSION

The hypothesis, that narrow pedicles lead to a higher perforation rate of the pedicle wall, can be accepted. Pedicles of <6.6mm turned out to be a risk factor for a perforation of the pedicle wall (GRGr 2 or higher). Intraoperative 3D imaging is a feasible tool to confirm optimal screw position, which becomes even more important in cases with thin pedicles. The rising risk of VA injury in these cases support the additional use of navigation.

Differences between Manufacturers of Computed Tomography-Based Computer-Assisted Surgery Systems Do Exist: A Systematic Literature Review

STUDY DESIGN

Literature review.

OBJECTIVE

Several studies have shown that the accuracy of pedicle screw placement significantly improves with use of computed tomography (CT)-based navigation systems. Yet, there has been no systematic review directly comparing accuracy of pedicle screw placement between different CT-based navigation systems. The objective of this study is to review the results presented in the literature and compare CT-based navigation systems relative only to screw placement accuracy.

METHODS

Data sources included CENTRAL, Medline, PubMed, and Embase databases. Studies included were randomized clinical trials, case series, and case-control trials reporting the accuracy of pedicle screws placement using CT-based navigation. Two independent reviewers extracted the data from the selected studies that met our inclusion criteria. Publications were grouped based on the CT-based navigation system used for pedicle screw placement.

RESULTS

Of the 997 articles we screened, only 26 met all of our inclusion criteria and were included in the final analysis, which showed a significant statistical difference (p < 0.0001, 95% confidence interval 0.92 to 1.23) in accuracy of pedicle screw placement between three different CT-based navigation systems. The mean (weighted) accuracy of pedicle screws placement based on the CT-based navigation system was found to be 97.20 ± 2.1% in StealthStation (Medtronic, United States) and 96.1 ± 3.9% in VectorVision (BrainLab, Germany).

CONCLUSION

This review summarizes results presented in the literature and compares screw placement accuracy using different CT-based navigation systems. Although certain factors such as the extent of the procedure and the experience and skills of the surgeon were not accounted for, the differences in accuracy demonstrated should be considered by spine surgeons and should be validated for effects on patients' outcome.

Cervical screw placement using rapid prototyping drill templates for navigation: a literature review

PURPOSE

Due to the high screw malposition rate and the potential risk of neurovascular injury in cervical fixation surgeries, guided tools, mainly computer-assisted surgery navigation systems and rapid prototyping drill templates (RPDTs) have increasingly been developed to help surgeons improve screw placement accuracy. Although RPDTs have been used in cervical surgeries for almost 2 decades, no specific review has been performed detailing the state of this technique. Thus, in the current review, we fully discuss the status of applying RPDTs in cervical surgeries.

METHODS

Studies that tested the accuracy and reliability of RPDTs in guiding cervical screw placements were included in this review. The fabrication workflow and usage of RPDTs, the accuracy and reliability of using RPDTs for screw and plate placement, the advantages and disadvantages of RPDTs and their prospects for future applications as a part of cervical fixation instrumentation are discussed.

RESULTS

As the design of RPDTs becomes more rational, the accuracy and reliability of these devices have significantly improved in cervical fixation surgeries. Moreover, RPDTs decrease the intraoperative radiation exposure for surgeons and patients relative to conventional methods. However, some disadvantages also exist. The fabrication of RPDTs is time-consuming, and the time required to learn the related software is long.

CONCLUSION

We believe that because of their merits, the RPDT technique is worth promoting for use in cervical surgeries. However, the time-consuming fabrication workflow and the long period required to learn the related software might limit its widespread use. In the future, the workflow should be simplified to reduce the extra workload for surgeons. Moreover, more clinical studies with high-level evidence are still needed to further test its accuracy and feasibility.

Complications of Anterior and Posterior Cervical Spine Surgery

Cervical spine surgery performed for the correct indications yields good results. However, surgeons need to be mindful of the many possible pitfalls. Complications may occur starting from the anaesthestic procedure and patient positioning to dura exposure and instrumentation. This review examines specific complications related to anterior and posterior cervical spine surgery, discusses their causes and considers methods to prevent or treat them. In general, avoiding complications is best achieved with meticulous preoperative analysis of the pathology, good patient selection for a specific procedure and careful execution of the surgery. Cervical spine surgery is usually effective in treating most pathologies and only a reasonable complication rate exists.

Clinical application of three-dimensional printing in the personalized treatment of complex spinal disorders

PURPOSE

To investigate the usefulness of three-dimensional (3D) printing in complex spinal surgery.

METHODS

The study was conducted from October 2014 to March 2015 in Shenzhen Second Peoples' Hospital and 4 cases of complex severe spinal disorders were selected from our department. Among them one patient combined with congenital scoliosis, one with atlas neoplasm, one with atlantoaxial dislocation, and the rest one with atlantoaxial fracture-dislocation. The data of the diseased region was collected from computerized tomography scans for 3D digital reconstruction and rapid prototyping to prepare photosensitive resin models, which were applied in the treatment of these cases.

RESULTS

The use of 3D models reduced operating time and intraoperative blood loss as well as the risk of postoperative complications. Furthermore, no pedicle penetrations or screw misplacement occurred according to the postoperative planar radiographic images.

CONCLUSION

The tactile models from 3D printing allow direct observation and measurement, helping the orthopedists to have accurate morphometric information to provide personalized surgical planning and better communication with the patient and coworkers. Moreover, the photosensitive resin models can also guide the actual surgery with the drilling of pedicle screws and safe resection of tumor.

Accuracy of 3D fluoroscopy-navigated anterior transpedicular screw insertion in the cervical spine: an experimental study

PURPOSE

The technique of pedicle screw stabilization is finding increasing popularity for use in the cervical spine. Implementing anterior transpedicular screws (ATPS) in cervical spine offers theoretical advantages compared to posterior stabilization. The goal of the current study was the development of a new setting for navigated insertion of ATPS, combining the advantage of reduced invasiveness of an anterior approach with the technical advantages of navigation.

METHODS

20 screws were implanted in levels C3 to C6 of four cervical spine models (SAWBONES(®) Cervical Vertebrae with Anterior Ligament) with the use of 3D fluoroscopy navigation system [Arcadis Orbic 3D, Siemens and VectorVision fluoro 3D trauma software (BrainLAB)]. The accuracy of inserted screws was analyzed according to postoperative CT scans and following the modified Gertzbein and Robbins classification.

RESULTS

20 anterior pedicle screws were placed in four human cervical spine models. Of these, eight screws were placed in C3, two screws in C4, six screws in C5, and four screws in C6. 16 of 20 screws (80 %) reached a grade 1 level of accuracy according to the modified Gertzbein and Robbins Classification. Three screws (15 %) were grade 2, and one screw (5 %) was grade 3. Grade 4 and 5 positions were not evident. Summing grades 1 and 2 together as "good" positions, 95 % of the screws achieved this level. Only a single screw did not fulfill these criteria.

CONCLUSION

The setting introduced in this study for navigated insertion of ATPS into cervical spine bone models is well implemented and shows excellent results, with an accuracy of 95 % (Gertzbein and Robbins grade 2 or better). Thus, this preliminary study represents a prelude to larger studies with larger case numbers on human specimens.

Comparison of navigated versus non-navigated pedicle screw placement in 260 patients and 1434 screws: screw accuracy, screw size, and the complexity of surgery

OBJECTIVE

Computer 3D navigation (3D NAV) techniques in spinal instrumentation can theoretically improve screw placement accuracy and reduce injury to critical neurovascular structures, especially in complex cases. In this series, we analyze the results of 3D NAV in pedicle screw placement accuracy, screw outer diameter, and case complexity in comparison with screws placed with conventional lateral fluoroscopy.

METHODS

Pedicle screws placed in the cervical, thoracic, or lumbar spine using either standard lateral fluoroscopy or 3D NAV using isocentric fluoroscopy were retrospectively analyzed. The accuracy of each individual screw was graded on a 4-tiered classification system. Screw and pedicle diameter measurements were also made in both cohorts, and case complexity was compared between the 2 cohorts. Complex cases were defined as deformity surgery, re-do cases, and minimally invasive surgery.

RESULTS

A total of 708 screws were placed under 3D NAV guidance and 726 screws were placed without stereotaxy. Eighty-eight percent of 3D NAV-guided pedicle screws were graded nonbreach versus 82% of cases with lateral fluoroscopy (P<0.001). The ratio of screw/pedicle diameter was significantly larger in the 3D NAV cohort (0.71 vs. 0.63, P<0.05). Seventy-six percent of 3D NAV cases had a predefined aspect of complexity, whereas 44% of non-3D NAV cases met criteria to be labeled complex (P<0.001). Reoperation occurred less frequently in 3D NAV cases than fluoroscopy alone.

CONCLUSIONS

The use of 3D NAV was associated with improved screw placement accuracy, improved screw-to-pedicle diameter measurements, and was used in cases with a higher degree of surgical complexity. We conclude that 3D NAV is a valuable tool in current spinal instrumentation, especially for more complex surgeries.

Clinical Use of 3D Printing Guide Plate in Posterior Lumbar Pedicle Screw Fixation

Background

This study aimed to evaluate the clinical efficacy of use of a 3D printing guide plate in posterior lumbar pedicle screw fixation.

Material/Methods

We enrolled 43 patients receiving posterior lumbar pedicle screw fixation. The experimental group underwent 3D printing guide plate-assisted posterior lumbar pedicle screw fixation, while the control group underwent traditional x-ray-assisted posterior lumbar pedicle screw fixation. After surgery, CT scanning was done to evaluate the accuracy of screw placement according to the Richter standard.

Results

All patients were followed up for 1 month. The mean time of placement for each screw and the amount of hemorrhage was 4.9±2.1 min and 8.0±11.1 mL in the experimental group while 6.5±2.2 min and 59.9±13.0 mL in the control group, respectively, with significant differences (p<0.05). The fluoroscopy times of each screw placement was 0.5±0.4 in the experimental group, which was significantly lower than that in the control group 1.2±0.7 (p<0.05). The excellent and good screw placement rate was 100% in the experimental group and 98.4% in the control group, without any statistical difference (P>0.05). No obvious complications were reported in either group.

Conclusions

Compared with the traditional treatment methods, the intra-operative application of 3D printing guide plate can shorten the operation time and reduce the amount of hemorrhage. It can also reduce the fluoroscopy times compared with the traditional fluoroscopy, which cannot improve the accuracy rate of screw placement.

FREE-HAND PLACEMENT OF C7 PEDICLE SCREWS: A CADAVERIC STUDY

Objective : To evaluate the accuracy of free-hand pedicle screws placement at the seventh cervical vertebra. Methods : The authors have exposed the cervicothoracic junction of 9 adult cadavers (7 male and 2 female) preserved in formalin from the Faculty of Medicine of the Universidad Andina Néstor Cáceres Velásquez, city of Juliaca, Puno - Peru, locating the C7 vertebra based on anatomical parameters. According to previous publications, the entry point for the C7 pedicle was determined as 3-4mm lateral and 5-6mm superior to the center of the lateral mass, and the pedicle was drilled manually and instrumented with 3.5mm screws. After the screws placement, the C7 vertebrae were removed for radiographic analysis. Results : The authors were able to adequately locate the C7 entry point in 12 pedicles (66.6% accuracy), finding a great variability both laterally (2-5mm) and cranially (3-10mm). The angulation in the coronal plane was correct in 13 pedicles (72.3%), despite the incorrect location of the entry point. Angle values in the coronal plane ranged from 38 to 62 degrees. In the sagittal plane angulation, 2 screws were placed in the C6-C7 disc. The midtransversal diameter of the 18 pedicles ranged from 4 to 7mm. Conclusions : The location of the entry point for placement of C7 pedicle screws with pure free-hand technique is very variable due to anatomical differences and the authors recommend some type of guidance for increased safety and accuracy.

Comparing Accuracy of Cervical Pedicle Screw Placement between a Guidance System and Manual Manipulation: A Cadaver Study

Background

The aim of this study was to compare the accuracy of cervical pedicle screw placement between a three-dimensional guidance system and manual manipulation.

Material/Methods

Eighteen adult cadavers were randomized into group A (n=9) and group B (n=9). Ninety pedicle screws were placed into the C3-C7 under the guidance of a three-dimensional locator in group A, and 90 screws were inserted by manual manipulation in group B. The cervical spines were scanned using computed tomography (CT). Parallel and angular offsets of the screws were compared between the two placement methods.

Results

In group A, 90% of the screws were within the pedicles and 10% breached the pedicle cortex. In group B, 55.6% were within the pedicle and 44.4% breached the pedicle cortex. Locator guidance showed significantly lower parallel and angular offsets in axial CT images (P<0.01), and significantly lower angular offset in sagittal CT images (P<0.01) than manual manipulation.

Conclusions

Locator guidance is superior to manual manipulation in accuracy of cervical screw placement. Locator guidance might provide better safety than manual manipulation in placing cervical screws.

Morphometric analysis of the seventh cervical vertebra for pedicle screw insertion

BACKGROUND

Anatomy of the pedicles of the seventh cervical vertebra (C7) at the cervicothoracic junction is different from other cervical vertebrae. Fixation of C7 is required during cervical vertebra and upper thoracic injuries in clinical practice. However, the typical pedicle screw insertion methods may have problems in clinical practice based on the anatomical features of C7. This study is to explore a new pedicle screw insertion technique for C7 and to provide anatomical and radiographic basis for clinical application.

MATERIALS AND METHODS

C7 vertebral specimens from six human cadavers were observed for the relative position between the posterior bony landmark and the pedicle projection. Computed tomography (CT) was performed for 30 patients with cervical spondylosis (26-61 years old, mean age was 42.3 years old). The CT scan data were processed by Mimics 8.1 software for associated parameter measurement. Appropriate screw entry points (Eps) and insertion angles were selected. A total of 12 pedicle screws were inserted and then observed. The six specimens were observed after inserting the screw using this method. The junction site of the middle 1/3 and outer 1/3 segment of line G [The junction between point A (the intersection point of the superior margin of the lamina of C7 and the medial margin of the superior articular process) and point B (the intersection point of the lateral margin of the inferior articular process and the transverse process)] was taken as the Ep. The screw insertion direction parallel horizontally to the upper terminal lamina of C7 and the sagittal angle was between 35° and 45°.

RESULTS

Gross and imaging observations revealed that pedicle projection was on the line (line G) between point A (the intersection point of the superior margin of the lamina of C7 and the medial margin of the superior articular process) and point B (the intersection point of the lateral margin of the inferior articular process and the transverse process) and located at the middle 1/3 and outer 1/3 segments of the line (point L[also it is the screw entry points (Eps)]. No significant difference in the measurements on the left and right sides were observed (P > 0.05). No penetration of the 12 screws through pedicle was observed.

CONCLUSION

The junction site of the middle 1/3 and outer 1/3 segments of line G are the projection points of C7 pedicles on the lateral mass. The junction site anatomical position was simply and easy to be controlled during surgery, simultaneously avoided uncertainty of other methods. This study provides a new method for determining an Ep for C7 pedicle screw insertion.

Comparison of screw malposition and vertebral artery injury of C2 pedicle and transarticular screws: meta-analysis and review of the literature

STUDY DESIGN

Literature review and meta-analysis.

OBJECTIVES

To compare the incidence of screw malposition and vertebral artery injury (VAI) with transarticular screws (TAS) and C2 pedicle screws (C2PS) using meta-analysis techniques.

SUMMARY OF BACKGROUND DATA

Posterior instrumentation for atlantoaxial fusions can be challenging and risky. Some centers report a higher incidence of VAI with the implantation of TAS compared with C2PS, whereas other data do not support this.

METHODS

Online databases were searched for English language articles between 1994 and April 2011 describing the clinical and radiographic outcomes after insertion of C2PS or TAS. Forty-one studies reporting on 3627 TAS and 33 studies describing 2979 C2PS met inclusion criteria for VAI or clinically significant misplacements (VAI, neurological deficits, or misplacements requiring surgical revision), and 36 studies reporting on 3280 TAS and 28 studies describing 2532 C2PS met inclusion criteria for radiographic misplacement outcomes.

RESULTS

All studies comprised class III evidence. VAI occurred in 26 of 3627 (0.72%) implanted TAS and in 10 of 2979 (0.34%) implanted C2PS (P=0.01). Clinically significant misplacements occurred in 67 TAS (1.84%) and in 10 C2PS (0.34%; P<0.0001). The point estimate of VAI for TAS was 1.68% [confidence interval (CI), 1.23%-2.29%] and was higher than C2PS (1.09%; CI, 0.73%-1.63%; P=0.01). The point estimate of clinically significant screw malposition for TAS was 2.33% (CI, 1.61%-3.37%) and was higher than that of C2PS (1.15%; CI, 0.77%-1.70%; P<0.001).

CONCLUSIONS

With training, experience, and anatomic knowledge, both TAS and C2PS can be inserted accurately and safely. However, improper insertion and VAI can have catastrophic consequences. Our review identified a higher risk of VAI, neurological injury, and clinically significant malpositions with TAS compared with C2PS. These data provide preliminary support for the supposition that C2PS have a lower risk of morbidity.

Integration of fluoroscopy-based guidance in orthopaedic trauma surgery - a prospective cohort study

INTRODUCTION

Computer-assisted guidance systems are not used frequently for musculoskeletal injuries unless there are potential advantages. We investigated a novel fluoroscopy-based image guidance system in orthopaedic trauma surgery.

MATERIALS AND METHODS

The study was a prospective, not randomised, single-centre case series at a level I trauma centre. A total of 45 patients with 46 injuries (foot 12, shoulder 10, long bones seven, hand and wrist seven, ankle seven and spine and pelvis four) were included. Different surgical procedures were examined following the basic principles of the Arbeitsgemeinschaft für Osteosynthesefragen/Association for the Study of Internal Fixation (AO/ASIF). Main outcome measurements were the number of trials for implant placement, total surgery time, usability via user questionnaire and system failure rate.

RESULTS

In all cases, the trajectory function was used, inserting a total of 56 guided implants. The system failed when used in pelvic and spinal injuries, resulting in a total failure rate of 6.5% (n=3) of all included cases. The overall usability was rated as good, scoring 84.3%.

CONCLUSION

The novel image-guidance system could be integrated into the surgical workflow and was used successfully in orthopaedic trauma surgery. Expected advantages should be explored in randomised studies.

Computer aided surgery in foot and ankle: applications and perspectives

PURPOSE

At the beginning of the twenty-first century, the computer has supplemented the possibilities of orthopaedic surgery. This article analyses the feasibility and potential clinical benefit of intraoperative three-dimensional imaging (3D), computer assisted surgery (CAS) and intraoperative pedography (IP) in foot and ankle surgery.

METHODS

The feasibility, accuracy and clinical benefit of 3D, CAS and IP were analysed in ongoing experimental and prospective studies at the institution in which the inventor of IP and principal user of 3D and CAS in foot and ankle surgery operates.

RESULTS

Three dimensional imaging: In approximately one third of the cases, reduction/correction and/or implant position was corrected after intraoperative 3D scan during the same procedure in different prospective, consecutive, non-controlled studies (Level III). CAS: CAS guidance for the correction of deformities of the ankle, hindfoot and midfoot/tarsometatarsal (TMT) joint provided higher accuracy, a faster correction process and better scores at a minimum follow-up of two years in comparison without CAS guidance in a single-centre matched-pair follow-up study (Level II). IP: Additional use of IP as the only difference between two groups with correction and/or arthrodesis at foot and/or ankle led to improved clinical outcome scores at a mean of two years follow-up in a prospective randomised controlled study (Level I).

CONCLUSIONS

Three dimensional imaging provides important information which could not be obtained from two-dimensional C-arm alone. The benefit of CAS is high when improved accuracy may lead to an improved clinical outcome. Intraoperative pedography is useful when intraoperative biomechanical assessment may lead to an immediate improvement of the achieved surgical result.

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.

Minimally invasive anterior transarticular screw fixation and microendoscopic bone graft for atlantoaxial instability

PURPOSE

Even though transarticular screw (TAS) fixation has been commonly used for posterior C1-C2 arthrodesis in both traumatic and non-traumatic lesions, anterior TAS fixation C1-2 is a less invasive technique as compared with posterior TAS which produces significant soft tissue injury, and there were few reports on percutaneous anterior TAS fixation and microendoscopic bone graft for atlantoaxial instability. The goals of our study were to describe and evaluate a new technique for anterior TAS fixation of the atlantoaxial joints for traumatic atlantoaxial instability by analyzing radiographic and clinical outcomes.

METHODS

This was a retrospective study of seven consecutive patients with C1-C2 instability due to upper cervical injury treated by a minimally invasive procedure from May 2007 to August 2009. Bilateral anterior TAS were inserted by the percutaneous approach under Iso-C3D fluoroscopic control. The atlantoaxial joint space was prepared for morselized autogenous bone graft under microendoscopy. The data for analysis included time after the injuries, operating time, intraoperative blood loss, X-ray exposure time, clinical results, and complications. Radiographic evaluation included the assessment of atlantoaxial fusion rate and placement of TAS. Bone fusion of the atlantoaxial joints was assessed by flexion extension lateral radiographs and 1-mm thin-slice computed tomography images as radiographic results. Clinical assessment was done by analyzing the recovery state of clinical presentation from the preoperative period to the last follow-up and by evaluating complications.

RESULTS

A total of 14 screws were placed correctly. The atlantoaxial solid fusion without screw failure was confirmed by CT scan in seven cases after a mean follow-up of 27.5 months (range 18-45 months). All patients with associated clinical presentation made a recovery without neurologic sequelae. Postoperative dysphagia occurred and disappeared in two cases within 5 days after surgery. There were no other complications during the follow-up period.

CONCLUSIONS

Percutaneous anterior TAS fixation and microendoscopic bone graft could be an option for achieving C1-C2 stabilization with several potential advantages such as less tissue trauma and better accuracy. Bilateral TAS fixation and morselized autograft affords effective fixation and solid fusion by a minimally invasive approach.

Cervical pedicle screw insertion using the technique with direct exposure of the pedicle by laminoforaminotomy

Objective

To present the accuracy and safety of cervical pedicle screw insertion using the technique with direct exposure of the pedicle by laminoforaminotomy.

Methods

We retrospectively reviewed 12 consecutive patients. A total of 104 subaxial cervical pedicle screws in 12 patients had been inserted. We also assessed the clinical and radiological outcomes and analyzed the direction and grade of pedicle perforation (grade 0: no perforation, 1: <25%, 2: 20% to 50%, 3: >50% of screw diameter) on the postoperative vascular-enhanced computed tomography scans. Grade 2 and 3 were considered as incorrect position.

Results

The correct position was found in 95 screws (91.3%); grade 0-75 screws, grade 1-20 screws and the incorrect position in 9 screws (8.7%); grade 2-6 screws, grade 3-3 screws. There was no neurovascular complication related with cervical pedicle screw insertion.

Conclusion

This technique (technique with direct exposure of the pedicle by laminoforaminotomy) could be considered relatively safe and easy method to insert cervical pedicle screw.

Cervical pedicle screw fixation in traumatic cervical subluxation after laminectomy using the pedicle axis view technique under fluoroscopy

Cervical pedicle screw (CPS) fixation has recently been performed in patients in need of cervical reconstruction. We report the case of a 50-year-old man who was operated for traumatic cervical vertebra subluxation using CPS fixation, in whom laminectomy had been performed in the past. We performed CPS fixation using the pedicle axis view technique under fluoroscopy. The four pedicle screws were accurately inserted within the pedicles without perforating the bone cortex of the pedicles. A navigation system is useful for cervical spine surgery because it enables a surgeon to perform relatively safe and accurate surgery during transpedicular screw fixation. However, attachment of the stereotactic reference arc to the spinous process is impossible, and the application of a navigation system is limited in cases in which laminectomy has been performed in the past. We have been using the pedicle axis view technique under fluoroscopy and have found that if we take care of the entry point accurately, we can safely insert the pedicle screw in cases with fewer landmarks.

The management of vertebral artery injury in anterior cervical spine operation: a systematic review of published cases

PURPOSE

Anterior cervical spine operations (ACSO) are generally considered to be safe and effective, but the vertebral artery (VA) is at risk during the procedure. Because the consequences of VA injury can be catastrophic, properly managing a VA injury is very important. However, due to the rarity of these injuries, there is no agreed upon treatment strategy.

METHODS

Studies were identified for inclusion in the review via sensitive searches of electronic databases through 31 December 2011. All cases included in the review were qualitatively analyzed to explore the relationship between type of VA injury management and neurological complications.

RESULTS

Seventeen articles describing 39 cases of VA injury during ACSO were included in this study. Seven patients (17.9 %) had neurological complications followed by VA insufficiency. Two patients (5.1 %) had root damage due to ligation. One case (2.6 %) resulted in intraoperative death due to fatal bleeding. Delayed vascular complications were identified in nine (45.0 %) of the 20 patients that underwent only tamponade or hemostatic agent during the operation. Four patients underwent intraoperative endovascular treatment, and three of these patients had a cerebral infarction. All three patients who underwent clipping also had neurological complications. The five patients treated by direct repair did not have any complications.

CONCLUSION

Our review suggests the management of VA injury should be considered in order listed: (1) performing tamponade with a hemostatic agent, (2) direct repair, (3) postoperative endovascular procedures to prevent delayed complications. If tamponade fails to achieve proper hemostasis, additional procedures as endovascular embolization, clipping and ligation should be considered but carry the risk of neurological complications. Because of the limitations of this review, further studies are recommended with larger sample sizes.