Clinically significant pedicle screw malposition is an underestimated cause of radiculopathy

Assessing intraoperative pedicle screw placement accuracy using biplanar radiographs compared to three-dimensional imaging

To date, biplanar imaging (2D) has been the method of choice for pedicle screw (PS) positioning and verified for the anteroposterior view and (spinal midline) M-line method. In recent years, the use of intraoperative three-dimensional (3D) imaging has become available with the Gertzbein-Robbins system (GRS) to assess PS breach and positioning confirmation. The aim is to determine if 2D imaging is sufficient to assess PS position in comparison to advanced 3D imaging.Retrospective review of prospectively collected data from 204 consecutive adult patients who underwent posterior thoracic and lumbar instrumented fusion for degenerative spinal surgery by a single surgeon (2019-2022).Of the 204 patients, 187 (91.6%) had intraoperative images available for analysis. A total of 1044 PS implants were used; 922 (88.3%) were robotically placed. Postoperative CT scans were verified with M-line/GRS findings. Among 103 patients (50.5%) with a total of 362 screws, (34.7%) had postoperative CT, intraoperative 3D scan, and intraoperative 2D scan for analysis. Postoperative CT findings were consistent with all GRS findings, validating that 3D imaging was accurate. Screws (1%) were falsely verified by the M-line as 3D imaging confirmed false negative or positive findings.In our series, intraoperative 3D scan was as accurate as postoperative CT scan in assessing PS breach. A significant number of PS may be falsely read as accurate on 2D imaging, that is in fact inaccurate when assessed on 3D imaging. An intraoperative post-instrumentation 3D scan may be preferable to prevent postoperative recognition of a falsely verified screw on biplanar imaging.

How accurately can surgeons perform angle manipulation? Quantitative assessment of the accuracy of manual angle manipulation of orthopedic surgery: a cadaver study

INTRODUCTION

To date, only few studies have been performed on the accuracy of manual angle manipulation during orthopedic surgery. This cadaver study was aimed at quantitatively assessing the accuracy of manual angle manipulation performed by orthopedic surgeons according to their surgical experience and comparing it with manipulation performed with the assistance of a digital goniometer.

MATERIALS AND METHODS

Six lower-leg specimens of fresh-frozen human cadavers were subjected to angle manipulation performed via Kirschner wire (K-wire) insertion. K-wires were inserted manually and with the assistance of a digital goniometer at target angles of 0°, 30°, and 60° by three operators who had different levels of experience in orthopedic surgery. The accuracy of the insertion angles at the target angles was evaluated using computed tomography.

RESULTS

The mean angle error in the manual angle manipulation was 8.8° (standard deviation [SD] 6.0). When the target angles were set to 0°, 30°, and 60°, the identified angle errors were 6.1° (SD 4.3), 8.8° (SD 6.6), and 11.7° (SD 5.6), respectively, and each value did not show any significant difference among the operators. With the assistance of a digital goniometer, the mean (SD) angle error was significantly improved to 2.1° (1.1°) (p < 0.001). The amount of improvement in accuracy significantly increased as the target angle increased (p = 0.01).

CONCLUSION

This cadaver study quantified the inaccuracy of manual angle manipulation in orthopedic surgery and showed that these inaccuracies ​​can be improved using an assistive device. These results support the need to develop a device that can compensate manual angle manipulation in orthopedic surgery.

Augmented reality-navigated pedicle screw placement: a cadaveric pilot study

PURPOSE

Augmented reality (AR) is an emerging technology with great potential for surgical navigation through its ability to provide 3D holographic projection of otherwise hidden anatomical information. This pilot cadaver study investigated the feasibility and accuracy of one of the first holographic navigation techniques for lumbar pedicle screw placement.

METHODS

Lumbar computer tomography scans (CT) of two cadaver specimens and their reconstructed 3D models were used for pedicle screw trajectory planning. Planned trajectories and 3D models were subsequently uploaded to an AR head-mounted device. Randomly, k-wires were placed either into the left or the right pedicle of a vertebra (L1-5) with or without AR-navigation (by holographic projection of the planned trajectory). CT-scans were subsequently performed to assess accuracy of both techniques.

RESULTS

A total of 18 k-wires could be placed (8 navigated, 10 free hand) by two experienced spine surgeons. In two vertebrae, the AR-navigation was aborted because the registration of the preoperative plan with the intraoperative anatomy was imprecise due to a technical failure. The average differences of the screw entry points between planning and execution were 4.74 ± 2.37 mm in the freehand technique and 5.99 ± 3.60 mm in the AR-navigated technique (p = 0.39). The average deviation from the planned trajectories was 11.21° ± 7.64° in the freehand technique and 5.88° ± 3.69° in the AR-navigated technique (p = 0.09).

CONCLUSION

This pilot study demonstrates improved angular precision in one of the first AR-navigated pedicle screw placement studies worldwide. Technical shortcomings need to be eliminated before potential clinical applications.

Impact of Screw Diameter on Pedicle Screw Fatigue Strength-A Biomechanical Evaluation

OBJECTIVE

Loosening of pedicle screws is a frequently observed complication in spinal surgery. Because additional stabilization procedures such as cement augmentation or lengthening of the instrumentation involve relevant risks, optimal stability of the primarily implanted pedicle screw is of essential importance. The aim of the present study was to investigate the effect of increasing the screw diameter on pedicle screw stability.

METHODS

A total of 10 human cadaveric vertebral bodies (L4) were included in the present study. The bone mineral density was evaluated using quantitative computed tomography and the pedicle diameter using computed tomography. The vertebrae underwent instrumentation using 6.0-mm × 45-mm pedicle screws on 1 side and screws with the largest possible diameter (8-10-mm × 45-mm) on the other side. Fatigue testing was performed by applying a cyclic loading (craniocaudal sinusoidal 0.5 Hz) with increasing peak force (100 N + 0.1 N/cycle) until screw head displacement of 5.4 mm was reached.

RESULTS

The mean fatigue load was 334 N for the 6-mm diameter screws and was increased significantly to 454 N (+36%) for the largest possible diameter screws (P < 0.001). With an increase in the fatigue load by 52%, this effect was even more pronounced in vertebrae with reduced bone density (bone mineral density <120 mg/cm³; n = 7; P < 0.001). The stiffness of the construct was significantly greater in the largest diameter screw group compared with the standard screw group during the entire testing period (start, P < 0.001; middle, P < 0.001; end, P = 0.009).

CONCLUSIONS

Increasing the pedicle screw diameter from a standard 6-mm screw to the largest possible diameter (8-10 mm) led to a significantly greater fatigue load.

Demographic Analysis of Pedicle Diameter, and Estimated Pedicle Screw Length of the Lumbar Spine in a Diverse Population

BACKGROUND

Recent literature confirms the importance of understanding the variability in pedicle morphology among races. These studies suggest that more detailed and reliable measurements of pedicles should be undertaken. However, there is limited data on average pedicle diameters (PDs) or estimated pedicle screw lengths (EPSLs) between diverse racial populations. We sought to determine the differences in PD and EPSL in the lumbar spine between various races: "Asian," "Black," "White," and "Hispanic" to aid in perioperative planning during instrumented spinal fusion.

METHODS

Axial cuts of 404 patients were inspected to obtain their transverse outer cortical PD as measured through the isthmus, and EPSL by measuring the posterior entry point at the longest distance, which perpendicularly transected the measured isthmic diameter, to the anterior vertebral cortex from L1 to L5. We examined the average PD and PD range at each level for each race. To determine the significance, we used a mixed analysis of variance and a post hoc analysis.

RESULTS

In this retrospective chart review the races were found to be significantly different in PD and EPSL (P < .001). Post hoc analysis using Dunn-Bonferroni correction showed that Asians had significantly smaller PDs than Blacks and Whites (P < .002 and P < .014, respectively). The White and Hispanic population had significantly longer EPSLs when compared to Blacks and Asians from L1 to L5 (P < .01).

CONCLUSIONS

This study demonstrates that there are significant differences in pedicle morphology among races that must be taken into consideration when inserting pedicle screws during lumbar spinal fusion. Knowledge of these differences is of the utmost importance in order to limit complications while improving fixation.

LEVEL OF EVIDENCE

3.

CLINICAL RELEVANCE

Pedicle morphology is variable between races and understanding these differences is important for the safe placement of pedicle screws.

Use of Intraoperative Computed Tomography Improves Outcome of Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Single-Center Retrospective Cohort Study

OBJECTIVE

To provide data about surgical workflow, accuracy, complications, radiation exposure, and learning curve effect in patients who underwent minimally invasive (MIS) transforaminal lumbar interbody fusion with navigation coupled with mobile intraoperative computed tomography.

METHODS

A retrospective analysis was performed of data from consecutive patients who underwent single- or double-level MIS transforaminal lumbar interbody fusion at a single institution; mobile intraoperative computed tomography combined with a navigation system was used as the sole intraoperative imaging method to place pedicular screws; decompression and interbody fusion were performed through a 22-mm tubular retractor. Clinical data, perioperative complications, accuracy of pedicular screw placement, and radiation exposure were analyzed. A learning curve effect on surgical time and accuracy was assessed.

RESULTS

A total of 408 screws in 100 patients were analyzed. In all cases, spinal navigation allowed for identification of pedicular trajectories and greatly facilitated nerve root decompression through the MIS approach. Overall accuracy according to Heary classification was 95.3%. Nineteen screws (4.7%) presented a minor lateral breach (<2 mm), not clinically significant. Surgical time, blood loss, and patient radiation exposure compared favorably with reported values from other series using three-dimensional navigation. A learning curve effect on surgical time, but not on screw accuracy, was identified.

CONCLUSIONS

MIS transforaminal lumbar interbody fusion can now be performed without any radiation exposure to the surgeon and operating room staff, with almost absolute accuracy during screw positioning and tubular decompression. A learning curve effect on surgical time, but not on overall screw accuracy, may be expected.

Effective dose and image quality for intraoperative imaging with a cone-beam CT and a mobile multi-slice CT in spinal surgery: A phantom study

PURPOSE

To compare the effective dose (ED) and image quality (IQ) of O-arm cone-beam CT (Medtronic, Minneapolis, MN, USA) and Airo multi-slice CT (Brainlab AG, Munich, Germany) for intraoperative-CT (i-CT) in spinal surgery.

METHODS

The manufacturer-defined protocols available in the O-arm and Airo systems for three-dimensional lumbar spine imaging were compared. Organ dose was measured both with thermo-luminescent dosimeters and GafChromic films in the Alderson RadiationTherapy anthropomorphic phantom. A subjective analysis was performed by neurosurgeons to compare the clinical IQ of the anthropomorphic phantom images acquired with the different i-CT systems and imaging protocols. Image uniformity, noise, contrast-to-noise-ratio (CNR), and spatial resolution were additionally assessed with the Catphan 504 phantom.

RESULTS

O-arm i-CT caused 56% larger ED than Airo due to the high definition (HD) imaging protocol. The noise was larger for O-arm images leading to a lower CNR than that measured for Airo. Moreover, scattering and beam hardening effects were observed in the O-arm images. Better spatial resolution was measured for the O-arm system (9 lp/cm) than for Airo (4 lp/cm). For all the investigated protocols, O-arm was found to be better for identifying anatomical features important for accurate pedicle screw positioning.

CONCLUSIONS

According to phantom measurements, the HD protocol of O-arm offered better clinical IQ than Airo but larger ED. The larger noise of O-arm images did not compromise the clinical IQ while the superior spatial resolution of this system allowed a better visibility of anatomical features important for pedicle screw positioning in the lumbar region.

Retrospective Review of Revision Surgery After Image-guided Instrumented Spinal Surgery Compared With Traditional Instrumented Spinal Surgery

STUDY DESIGN

Retrospective cohort series.

OBJECTIVE

The objective of this study was to determine if the use of image-guided navigation offers a clinically significant advantage over fluoroscopy-assisted pedicle screw and non-navigated screw placement in reducing the risk of revision surgery for malpositioned screws in instrumented spinal surgery.

SUMMARY OF BACKGROUND DATA

Use image-guided navigation has become increasingly commonplace in instrumented spine surgery, but there is a lack of information regarding differences in the rates of clinically relevant screw malposition with image-guided compared with non-navigated screw placement.

MATERIALS AND METHODS

This is a retrospective cohort series of consecutive patients who underwent instrumented spinal surgery by the senior authors at 2 academic tertiary care centers in New York.

RESULTS

A total of 663 instrumented spinal surgeries were analyzed, including 271 instances with image-guided navigation. For the image-guided navigation cohort, 110 of the patients underwent screw placement using O-Arm image-guidance, yielding data on 1115 screws. The remaining 161 surgeries utilizing image-guided screw placement were performed using Brainlab Spine Navigation, for a total of 1001 screws. A fluoroscopy-assisted technique or freehand technique was used in 419 instances, with a total of 3689 screws. Of the non-navigated cohort, 10 patients required a surgical revision of screw placement, for a total of 15 malpositioned screws. Amongst the image-guided navigation cohort, 1 patient in the O-Arm group and 2 in the Brainlab group required revision surgery, with 3 malpositioned screws in total. The rate of revision surgery for a malpositioned screw placed via non-navigated techniques was 2.39%. This risk was decreased to 1.11% with the use of the intraoperative image-guided navigation. However, no comparisons between non-navigated and image-guided screw placement reached statistical significance.

CONCLUSION

Although not reaching statistical significance, these data suggest there may be an advantage offered by image-guided screw placement in instrumented spinal surgery.

Endoscopy-Assisted Diagnosis and Revision of a Malpositioned Screw

BACKGROUND

Pedicle screw insertion is a common procedure in spine surgery, and freehand, fluoroscopic, and robotic-assisted techniques all are used. These are indirect methods that use fluoroscopy, and direct visualization of canal involvement has not been possible. However, owing to the development of high-definition imaging modalities, delicate procedures that use endoscopy are possible.

CASE DESCRIPTION

A 47-year-old man presented with severe radiating pain in his leg after undergoing L5-S1 level endoscopic transforaminal lumbar interbody fusion and percutaneous pedicular screw fixation. The patient then underwent an endoscopy-assisted technique for violated spinal canal and screw revision in which the misplaced screw was directly visualized using endoscopy and the trajectory of the misplaced screw was changed. With 30° endoscopy, we directly visualized the screw thread and root compression. Then with 0° endoscopy, we changed the screw trajectory inside the pedicle with an anatomic landmark. The patient's radiating pain was completely relieved after revision of the malpositioned screw. Postoperative imaging showed the revised screw trajectory inside the pedicle.

CONCLUSIONS

Endoscopy-assisted pedicle screw insertion does not require an additional incision, and early recovery after the procedure is possible. Accurate diagnosis of canal pathology and treatment are possible with direct visualization using endoscopy.

The European Robotic Spinal Instrumentation (EUROSPIN) study: protocol for a multicentre prospective observational study of pedicle screw revision surgery after robot-guided, navigated and freehand thoracolumbar spinal fusion

INTRODUCTION

Robotic guidance (RG) and computer-assisted navigation (NV) have seen increased adoption in instrumented spine surgery over the last decade. Although there exists some evidence that these techniques increase radiological pedicle screw accuracy compared with conventional freehand (FH) surgery, this may not directly translate to any tangible clinical benefits, especially considering the relatively high inherent costs. As a non-randomised, expertise-based study, the European Robotic Spinal Instrumentation Study aims to create prospective multicentre evidence on the potential comparative clinical benefits of RG, NV and FH in a real-world setting.

METHODS AND ANALYSIS

Patients are allocated in a non-randomised, non-blinded fashion to the RG, NV or FH arms. Adult patients that are to undergo thoracolumbar pedicle screw instrumentation for degenerative pathologies, infections, vertebral tumours or fractures are considered for inclusion. Deformity correction and surgery at more than five levels represent exclusion criteria. Follow-up takes place at 6 weeks, as well as 12 and 24 months. The primary endpoint is defined as the time to revision surgery for a malpositioned or loosened pedicle screw within the first postoperative year. Secondary endpoints include patient-reported back and leg pain, as well as Oswestry Disability Index and EuroQOL 5-dimension questionnaires. Use of analgesic medication and work status are recorded. The primary analysis, conducted on the 12-month data, is carried out according to the intention-to-treat principle. The primary endpoint is analysed using crude and adjusted Cox proportional hazards models. Patient-reported outcomes are analysed using baseline-adjusted linear mixed models. The study is monitored according to a prespecified monitoring plan.

ETHICS AND DISSEMINATION

The study protocol is approved by the appropriate national and local authorities. Written informed consent is obtained from all participants. The final results will be published in an international peer-reviewed journal.

TRIAL REGISTRATION NUMBER

Clinical Trials.gov registry NCT03398915; Pre-results, recruiting stage.

[Diagnosis and interventional treatment of pain syndromes after surgery for degenerative lumbar spine diseases]

Postoperative pain accompanies up to 20% of interventions for degenerative spine diseases (DSDs). The epidemiologic data are contradictory; clinical and radiological diagnostics is often low efficient; capabilities of interventional diagnosis and treatment techniques are poorly understood.

PURPOSE

The study purpose was to investigate the structure of pain syndromes after surgery for DSDs of the lumbar spine, based on complex diagnostics, as well as to evaluate the capabilities of interventional treatment.

MATERIAL AND METHODS

We examined 310 patients with postoperative pain syndromes. Patients with obvious indications for repeated surgery were excluded from the analysis; the remaining patients underwent selective diagnostic blockades followed by interventional (puncture) treatment. A positive outcome was defined as a reduction in pain by 50% on the numerical rating scale (NRS-11), by 20% in the Oswestry index (ODI), and by 8 points in the sciatica bothersomeness index (SBI), with the effect lasting for 12 months. Predictive factors for the risk of pain syndromes were analyzed.

RESULTS

Out of 310 patients, 162 (52.6%) patients had no obvious indications for surgery. Radicular pain was detected in 56 (18.6%) of 310 patients; the positive treatment outcome was achieved in 38 (67.86%) of 56 patients. Facet pain was present in 29 (9.35%) patients; the positive treatment outcome was achieved in 23 (79.31%) patients. Discogenic pain was found in 12 (3.87%) patients; the positive treatment outcome was achieved in 5 (41.63%) patients. sacroiliac joint (SIJ) pain was present in 42 (13.55%) patients; the positive treatment outcome was achieved in 36 (85.71%) patients. Myofascial and competing pain was detected in 12 (3.87%) patients; the causes were not identified in 11 (3.55%) cases. The main risk factors were sagittal balance parameters.

CONCLUSION

Complex diagnostics revealed postoperative pain not associated with surgical causes in 52.6% of cases; the origin of pain was identified in 49.95% of cases. Interventional treatment was effective in 64.81% of cases; failed back surgery syndrome was diagnosed in 16.13% of patients.