Pediatric pedicle screws: comparative effectiveness and safety: a systematic literature review from the Scoliosis Research Society and the Pediatric Orthopaedic Society of North America task force

Fully automated determination of robotic pedicle screw accuracy and precision utilizing computer vision algorithms

Historically, pedicle screw accuracy measurements have relied on CT and expert visual assessment of the position of pedicle screws relative to preoperative plans. Proper pedicle screw placement is necessary to avoid complications, cost and morbidity of revision procedures. The aim of this study was to determine accuracy and precision of pedicle screw insertion via a novel computer vision algorithm using preoperative and postoperative computed tomography (CT) scans. Three cadaveric specimens were utilized. Screw placement planning on preoperative CT was performed according to standard clinical practice. Two experienced surgeons performed bilateral T2-L4 instrumentation using robotic-assisted navigation. Postoperative CT scans of the instrumented levels were obtained. Automated segmentation and computer vision techniques were employed to align each preoperative vertebra with its postoperative counterpart and then compare screw positions along all three axes. Registration accuracy was assessed by preoperatively embedding spherical markers (tantalum beads) to measure discrepancies in landmark alignment. Eighty-eight pedicle screws were placed in 3 cadavers' spines. Automated registrations between pre- and postoperative CT achieved sub-voxel accuracy. For the screw tip and tail, the mean three-dimensional errors were 1.67 mm and 1.78 mm, respectively. Mean angular deviation of screw axes from plan was 1.58°. For screw mid-pedicular accuracy, mean absolute error in the medial-lateral and superior-inferior directions were 0.75 mm and 0.60 mm, respectively. This study introduces automated algorithms for determining accuracy and precision of planned pedicle screws. Our accuracy outcomes are comparable or superior to recent robotic-assisted in vivo and cadaver studies. This computerized workflow establishes a standardized protocol for assessing pedicle screw placement accuracy and precision and provides detailed 3D translational and angular accuracy and precision for baseline comparison.

Comparative Analysis of Monoaxial and Polyaxial Pedicle Screws in the Surgical Correction of Adolescent Idiopathic Scoliosis

Background: Although several biomechanical studies have been reported, few clinical studies have compared the efficacy of monoaxial and polyaxial pedicle screws in the surgical treatment of adolescent idiopathic scoliosis (AIS). This study aims to compare the radiological and clinical outcomes of mono- and polyaxial pedicle screws in the surgical treatment of AIS. Methods: A total of 46 AIS patients who underwent surgery to treat scoliosis using pedicle screw instrumentation (PSI) and rod derotation (RD) were divided into two groups according to the use of pedicle screws: the monoaxial group (n = 23) and polyaxial group (n = 23). Results: The correction rate of the main Cobb's angle was higher in the monoaxial group (70.2%) than in the polyaxial group (65.3%) (p = 0.040). No differences in the rotational correction of the apical vertebra were evident between the two groups. SRS-22 scores showed no significant differences according to the type of pedicle screws used. Conclusions: The use of polyaxial pedicle screws resulted in coronal, sagittal, and rotational correction outcomes comparable to those associated with the use of monoaxial pedicle screws for surgical treatment using PSI and RD to treat moderate cases of AIS.

Pedicle screw accuracy placed with assistance of machine vision technology in patients with neuromuscular scoliosis

INTRODUCTION

Pedicle screws are the primary method of vertebral fixation in scoliosis surgery, but there are lingering concerns over potential malposition. The rates of pedicle screw malposition in pediatric spine surgery vary from 10% to 21%. Malpositioned screws can lead to potentially catastrophic neurological, vascular, and visceral complications. Pedicle screw positioning in patients with neuromuscular scoliosis is challenging due to a combination of large curves, complex pelvic anatomy, and osteopenia. This study aimed to determine the rate of pedicle screw malposition, associated complications, and subsequent revision from screws placed with the assistance of machine vision navigation technology in patients with neuromuscular scoliosis undergoing posterior instrumentation and fusion.

METHOD

A retrospective analysis of the records of patients with neuromuscular scoliosis who underwent thoracolumbar pedicle screw insertion with the assistance of machine-vision image guidance navigation was performed. Screws were inserted by either a staff surgeon, orthopaedic fellow, or orthopaedic resident. Post-operative ultra-low dose CT scans were used to assess pedicle screw accuracy. The Gertzbein classification was used to grade any pedicle breaches (grade 0, no breach; grade 1, <2 mm; grade 2, 2-4 mm; grade 3, >4 mm). A screw was deemed accurate if no breach was identified (grade 0).

RESULTS

25 patients were included in the analysis, with a mean age of 13.6 years (range 11 to 18 years; 13/25 (52.0%) were female. The average pre-operative supine Cobb angle was 90.0 degrees (48-120 degrees). A total of 687 screws from 25 patients were analyzed (402 thoracic, 241 lumbosacral, 44 S2 alar-iliac (S2AI) screws). Surgical trainees (fellows and orthopaedic residents) inserted 46.6% (320/687) of screws with 98.8% (4/320) accuracy. The overall accuracy of pedicle screw insertion was 98.0% (Grade 0, no breach). All 13 breaches that occurred in the thoracic and lumbar screws were Grade 1. Of the 44 S2AI screws placed, one screw had a Grade 3 breach (2.3%) noted on intra-operative radiographs following rod placement and correction. This screw was subsequently revised. None of the breaches resulted in neuromonitoring changes, vessel, or visceral injuries.

CONCLUSION

Machine vision navigation technology combined with careful free-hand pedicle screw insertion techniques demonstrated high levels of pedicle screw insertion accuracy, even in patients with challenging anatomy.

The Influence of Increased Pedicle Screw Diameter and Thicker Rods on Surgical Results in Adolescents Undergoing Posterior Spinal Fusion for Idiopathic Scoliosis

Background: Modern surgical techniques allow for the correction of spinal deformity, stopping its progression and improving pain relief and social and physical functioning. These instruments have different implant designs, screws, and rod diameters and can be composed of different metal alloys with different hardnesses, which can have a significant impact on the effect of correcting spinal deformities. We designed a retrospective cohort study based on the same surgical technique and spine system using different implant sizes, and compared the results across them. Methods: This is a retrospective review of adolescent idiopathic scoliosis (AIS) patients who underwent posterior spinal fusion (PSF) between 2016 and 2022 with a minimum two-year follow-up (FU) using two spinal implant systems: 5.5 and 6.0 mm diameter screws with double 5.5 mm titanium rods (Group 1 (G1)), and 6.0 and 6.5 mm diameter pedicle screws with double 6.0 mm cobalt-chromium rods (Group 2 (G2)). The evaluated data were as follows: preoperative personal data, radiographic outcomes, complications, and health-related quality of life questionnaire (HRQoL). The parameters were reviewed preoperatively, after the final fusion, and during the FU. Results: The mean age of all 260 patients at surgery was 14.8 years. The average BMI was also similar in both groups and was noted as 21. The mean levels of fusion and screw density were similar in both groups. The mean preoperative major curves (MCs) were 57.6° and 62.5° in G1 and G2, respectively. The mean flexibility of the curves was noted as 35% in G1 and 33% in G2. After definitive surgery, the mean percentage correction of the MC was better in G2 vs. G1, with 74.5% vs. 69.8%, respectively (p < 0.001). At the final FU, the average loss of correction was 5.9° for G1 and 3.2° for G2 (p < 0.001). The mean preoperative (TK) thoracic kyphosis (T2-T5) was 12.2° in G1 and 10.8° in G2. It was corrected to 15.2° in G1 and to 13° in G2. At the FFU, we noted a significant difference in the TK (T2-T5) between the groups, with 16.7° vs. 9.6° for G1 vs. G2, respectively (p < 0.001). Statistical significance was observed between the preoperative sagittal balance and the final follow-up for both groups (p < 0.001). Conclusions: AIS patients surgically treated with screws with a larger diameter and thicker and stiffer rods showed greater correction and postoperative thoracic kyphosis without implant failure. The complication rates, implant density, and clinical outcomes remained similar. The radiographic benefits reported in this cohort study suggest that large-sized screws and stiffer rods for the correction of pediatric spinal deformities are safe and very effective.

Radiation exposure in navigated techniques for AIS: is there a difference between pre-operative CT and intraoperative CT?

PURPOSE

Utilization of navigation improves pedicle screw accuracy in adolescent idiopathic scoliosis (AIS). Our center switched from intraoperative CT (ICT) to an optical navigation system that utilizes pre-operative CT (PCT). We aim to evaluate the radiation dose and operative time for low-dose ICT compared to standard and low-dose PCT used for optical navigation in AIS patients undergoing posterior spinal fusion.

METHODS

A single-center matched-control cohort study of 38 patients was conducted. Nineteen patients underwent ICT navigation (O-arm) and were matched by sex, age, and weight to 19 patients who underwent PCT for use with an optical-guided navigation (7D, Seaspine). A total of 418 levels were instrumented and reviewed. PCT was either a standard dose (N = 7) or a low dose (N = 12). The mean volume CT dose index, dose-length product, overall effective dose (ED), ED per level instrumented, and operative time per level were compared.

RESULTS

ED per level instrumented was 0.061 ± 0.029 mSv in low-dose PCT and 0.14 ± 0.05 mSv in low-dose ICT (p < 0.0001). ED per level instrumented was significantly higher in standard PCT (1.46 ± 0.39 vs. 0.14 ± 0.03 mSv; p < 0.0001). Mean operative time per level was 31 ± 7 min for ICT and 33 ± 3 min for PCT (p = 0.628).

CONCLUSION

Low-dose PCT resulted in 0.70 mSv exposure per case and 31 min per level, standard-dose was 16.95 mSv, while ICT resulted in 1.34-1.62 mSv and a similar operative time. Use of a standard-dose PCT involves radiation exposure about 9 times higher than ICT and 23 times higher than low-dose PCT per level instrumented.

LEVEL OF EVIDENCE

Level III.

The Effect of Implant Density on Adolescent Idiopathic Scoliosis Fusion: Results of the Minimize Implants Maximize Outcomes Randomized Clinical Trial

BACKGROUND

Severe adolescent idiopathic scoliosis (AIS) can be treated with instrumented fusion, but the number of anchors needed for optimal correction is controversial.

METHODS

We conducted a multicenter, randomized study that included patients undergoing spinal fusion for single thoracic curves between 45° and 65°, the most common form of operatively treated AIS. Of the 211 patients randomized, 108 were assigned to a high-density screw pattern and 103, to a low-density screw pattern. Surgeons were instructed to use ≥1.8 implants per spinal level fused for patients in the high-implant-density group or ≤1.4 implants per spinal level fused for patients in the low-implant-density group. The primary outcome measure was the percent correction of the coronal curve at the 2-year follow-up. The power analysis for this trial required 174 patients to show equivalence, defined as a 95% confidence interval (CI) within a ±10% correction margin with a probability of 90%.

RESULTS

In the intention-to-treat analysis, the mean percent correction of the coronal curve was equivalent between the high-density and low-density groups at the 2-year follow-up (67.6% versus 65.7%; difference, -1.9% [95% CI: -6.1%, 2.2%]). In the per-protocol cohorts, the mean percent correction of the coronal curve was also equivalent between the 2 groups at the 2-year follow-up (65.0% versus 66.1%; difference, 1.1% [95% CI: -3.0%, 5.2%]). A total of 6 patients in the low-density group and 5 patients in the high-density group required reoperation (p = 1.0).

CONCLUSIONS

In the setting of spinal fusion for primary thoracic AIS curves between 45° and 65°, the percent coronal curve correction obtained with use of a low-implant-density construct and that obtained with use of a high-implant-density construct were equivalent.

LEVEL OF EVIDENCE

Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Effect of Pedicle Screw Size on Surgical Outcomes Following Surgery for 412 Adolescent Idiopathic Scoliosis Patients

STUDY DESIGN

Retrospective Review.

OBJECTIVE

The objective of this study was to determine differences in surgical and post-operative outcomes in AIS patients undergoing spinal deformity correction surgery using standard or large pedicle screw size.

SUMMARY OF BACKGROUND

Use of pedicle screw fixation in spinal deformity correction surgery is considered safe and effective. Still, the small size of the pedicle and the complex 3D anatomy of the thoracic spine makes screw placement challenging, with improper pedicle screw fixation leading to catastrophic complications including injuries to nerve roots, spinal cord, and major vessels. Thus, insertion of larger diameter screw sizes has raised concerns amongst surgeons, especially in the pediatric population.

MATERIALS AND METHODS

AIS patients undergoing PSF between 2013 and 2019 were included. Demographic, radiographic, and operative outcomes collected. Patients in the large screw size group (GpI) received 6.5 mm diameter screw sizes at all levels while standard screw size group (GpII) received 5.0 to 5.5 mm diameter screw sizes at all levels. Kruskall-Wallis and Fisher's exact test performed for continuous and categorical variables respectively.Subanalyses included (1) screw accuracy in patients with available CT scans, (2) stratified analysis of large- and standard-screw patients with ≥60% flexibility rate, (3) stratified analysis of large- and standard-screw patients with <60% flexibility rate, and (4) matched analysis of large- and standard-screw patients by surgeon and year of surgery.

RESULTS

GpI patients experienced significantly higher overall curve correction ( P <0.001), with 87.6% experiencing at least one grade reduction of apical vertebral rotation from preoperative to postoperative visit( P =0.008).Patients with larger screws displayed higher postoperative kyphosis. No patient experienced medial breaching.

CONCLUSION

Large screw sizes have similar safety profiles to standard screws without negatively impacting surgical and perioperative outcomes in AIS patients undergoing PSF. Additionally, coronal, sagittal, and rotational correction is superior for larger-diameter screws in AIS patients.

Biomechanical Computational Study of Pedicle Screw Position and Density in Adolescent Idiopathic Scoliosis Instrumentation

STUDY DESIGN

Computer simulation of adolescent idiopathic scoliosis instrumentation.

OBJECTIVE

To test the hypothesis that different screw densities would result in different apical vertebral rotation (AVR) corrections and bone-screw forces in adolescent idiopathic scoliosis instrumentation.

SUMMARY OF BACKGROUND DATA

The "Minimize Implants Maximize Outcomes" Clinical Trial revealed that the use of more versus fewer screws resulted in similar coronal plane correction for Lenke 1A curves. However, the biomechanical impact of screw density on transverse plane correction is still unclear. Further investigation is needed to determine if and how transverse plane correction is correlated with screw density.

PATIENTS AND METHODS

We simulated apical vertebral derotation after segmental translation using patient-specific computer models of 30 patients from the "Minimize Implants Maximize Outcomes" Trial. For each case, 10 alternative screw patterns were tested with overall densities ranging between 1.2 and 2 screws per level fused, and local density at the 3 apical levels ranging between 0.7 and 2 (total: 600 simulations). Main thoracic (MT) Cobb angle, thoracic kyphosis (TK), AVR, and bone-screw forces were computed and compared.

RESULTS

The presenting MT (62 ± 11°; range: 45° to 86°), TK (27 ± 20°; -5° to 81°), and AVR (14±7°; -2° to 25°) were corrected through segmental translation to 22 ± 7° (10° to 41°), 26 ± 5° (18° to 45°), and 14 ± 7° (-4° to 26°). After apical vertebral derotation, they became 16 ± 8° (1° to 41°), 24 ± 4° (13° to 40°), and 4 ± 5° (-12° to 18°). There was no significant difference in MT among screw patterns; higher screw density had lower bone-screw forces ( P < 0.05). The apical vertebral derotation maneuver reduced AVR by an average of 70%, positively correlated with apical screw density ( r = 0.825, P < 0.05). There was no significant difference in TK.

CONCLUSION

Screw density had no significant effect on 3-dimensional correction through the primary segmental translation maneuver. Transverse plane correction through subsequent apical vertebral derotation was positively correlated with screw density at the apical levels ( r = 0.825, P < 0.05). Bone-screw forces were negatively correlated with overall screw density ( P < 0.05).

Influences of Increasing Pedicle Screw Diameter on Widening Vertebral Pedicle Size during Surgery in Spinal Deformities in Children and Adolescents without Higher Risk of Pedicle and Vertebral Breaches

BACKGROUND

A very common technique for treating spinal deformities in children and adolescents is the use of segmental screws. In order to obtain proper stability and the best possible correction, the screws must first be precisely inserted. Additional factors influencing the quality and success of the operation are the size and quality of the bone, the skills of the surgeon, and biomechanical factors, i.e., the width and length of the screws used during surgery. Our study was focused on evaluating the effect of increasing the diameter of the instrumented pedicles by pedicle screws and assessing the safety of expanding these pedicles with screws of various sizes in children with spinal deformities during the growth period, using preoperative magnetic resonance imaging and postoperative computed tomography (CT) to assess and compare preoperative size measurements from MRI to postoperative CT measurements.

METHODS

We obtained data for evaluation from the available medical records and treatment histories of patients aged 2 to 18 who underwent surgical treatment of spinal deformities in the years 2016-2023. In 230 patients (28 male and 202 female), 7954 vertebral bodies were scanned by preoperative MRI, and 5080 pedicle screws were inserted during surgery, which were then assessed by postoperative CT scan. For the most accurate assessment, patients were classified into three age groups: 2-5 years (Group 1), 6-10 years (Group 2), and 11-18 years (Group 3). In addition, we studied implant subgroups: vertebral bodies with inserted pedicles of screw sizes 5.0 mm and 5.5 mm (Group S), and pedicles of screw sizes 6.0 mm, 6.5 mm, and 7.0 mm (Group L).

RESULTS

The morphology of pedicles (Lenke classification) analyzed before surgery using MRI was 55.2% type A, 33.8% type B, 4.7% type C, and 6.3% type D. The postoperative lateral and medial breaches were noted, and these did not cause any complications requiring revision surgery. The mean pedicle diameter before surgery for T1-L5 vertebral pedicles was between 3.79 (1.44) mm and 5.68 (1.64) mm. The mean expanding diameter of pedicles after surgery for T1-L5 vertebral pedicles ranged from 1.90 (0.39) mm to 2.92 (0.28) mm, which corresponds to the extension of the pedicle diameter in the mean range of 47% (4.1)-71% (3.0). We noted that the mean vertebral pedicle expansion was 49% in Group 1, 52% in Group 2, and 62% in Group 3 (N.S.), and the mean expansion for 7.0 mm screw pedicles was 78%.

CONCLUSIONS

Our study confirms that there is a wide range of expansion of the vertebral pedicle during screw insertion (up to 78%) with a low risk of lateral or medial breaches and without an increased risk of complications. The larger the diameter of the screw inserted into the pedicle, the more the pedicle expands. Pedicle measurements by preoperative MRI may be helpful for sufficient reliability in preoperative planning.

Accuracy and Safety of Pedicle Screw Placement for Treating Adolescent Idiopathic Scoliosis: A Narrative Review Comparing Available Techniques

Posterior spinal fusion and segmental spinal instrumentation using pedicle screws (PS) is the most used procedure to correct adolescent idiopathic scoliosis. Computed navigation, robotic navigation, and patient-specific drill templates are available, besides the first described free-hand technique. None of these techniques are recognized as the gold standard. This review compares the PS placement accuracy and misplacement-related complication rates achieved with the techniques mentioned above. It further reports PS accuracy classifications and anatomic PS misplacement risk factors. The literature suggests a higher PS placement accuracy for robotic relative to computed navigation and for the latter relative to the free-hand technique (misplacement rates: 0.4-7.2% versus 1.9-11% versus 1.5-50.7%) using variable accuracy classifications. The reported PS-misplacement-related complication rates are, however, uniformly low (0-1.4%) for every technique, while robotic and computed navigation induce a roughly fourfold increase in the patient's intraoperative radiation exposure relative to the free-hand technique with fluoroscopic implant positioning control. The authors, therefore, recommend dedicating robotic and computed navigation for complex deformities or revisions with altered landmarks, underline the need for a generally accepted PS accuracy classification, and advise against PS placement in grade 4 pedicles yielding higher misplacement rates (22.2-31.5%).

The Child's Age and the Size of the Curvature Do Not Affect the Accuracy of Screw Placement with the Free-Hand Technique in Spinal Deformities in Children and Adolescents

BACKGROUND

The current method of treatment of spinal deformities would be almost impossible without pedicle screws (PS) placement. There are only a few studies evaluating the safety of PS placement and possible complications in children during growth. The present study was carried out to evaluate the safety and accuracy of PS placement in children with spinal deformities at any age using postoperative computed tomography (CT) scans.

METHODS

318 patients (34 males and 284 females) who underwent 6358 PS fixations for pediatric spinal deformities were enrolled in this multi-center study. The patients were divided into three age groups: less than 10 years old, 11-13 years old, and 14-18 years old. These patients underwent postoperative CT scans and were analyzed for pedicle screw malposition (anterior, superior, inferior, medial, and lateral breaches).

RESULTS

The breach rate was 5.92% for all pedicles. There were 1.47% lateral and 3.12% medial breaches for all pedicles with tapping canals, and 2.66% lateral and 3.84% medial breaches for all pedicles without a tapping canal for the screw. Of the 6358 screws placed in the thoracic, lumbar, and sacral spine, 98% of the screws were accurately placed (grade 0, 1, and juxta pedicular). A total of 56 screws (0.88%) breached more than 4 mm (grade 3), and 17 (0.26%) screws were replaced. No new and permanent neurological, vascular, or visceral complications were encountered.

CONCLUSIONS

The free-hand technique for pedicle screw placement in the acceptable and safety zone in pedicles and vertebral bodies was 98%. No complications associated with screw insertion in growth were noted. The free-hand technique for pedicle screw placement can be safely used in patients at any age. The screw accuracy does not depend on the child's age nor the size of the deformity curve. Segmental instrumentation with posterior fixation in children with spinal deformities can be performed with a very low complication rate. Navigation of the robot is only an auxiliary tool in the hands of the surgeons, and the result of the work ultimately depends on the surgeons.

A Novel Pedicle Screw Design with Variable Thread Geometry: Biomechanical Cadaveric Study with Finite Element Analysis

BACKGROUND

Pedicle screw fixation provides one of the most stable spinal constructs. Their designs together with osseous characteristics have been known to influence the screw-bone interplay during surgical maneuvers and thereafter the fusion process. Various technical modifications to enhance screw performance have been suggested. This study evaluated the pull-out strength and axial stiffness of a novel pedicle screw design with variable thread geometry and pitch.

METHODS

The newly designed triple threaded pedicle screw is tapered, and has unique out-turned flanges to hold the cancellous bone and a finer pitch at its distal and proximal end to engage the cortical bone. Five lumbar and 4 lower thoracic cadaveric vertebrae were divided into hemivertebrae. A standard cancellous pedicle screw and the newly designed pedicle screw were inserted into each hemivertebra. Axial stiffness and peak pull-out force between the screw types were compared; a finite element analysis was also performed to additionally compare the pull out under toggle forces.

RESULTS

In cadaveric study, the axial stiffness of the new screw was significantly better than that of the standard screw. However, the peak load between the screws was not statistically different. Finite element analyses suggested lesser stress at bone-implant interface for the new screw along with better axial stiffness under both co-axial and toggle forces.

CONCLUSIONS

Our novel pedicle screw design with variable thread geometry demonstrates greater axial stiffness compared with the standard screws, and therefore is likely to withstand a greater surgical manipulation.

Comparative effectiveness of different pedicle screw density patterns in spinal deformity correction of small and flexible operative adolescent idiopathic scoliosis: inverse probability of treatment weighting analysis

PURPOSES

An optimal pedicle screw density for spinal deformity correction in adolescent idiopathic scoliosis (AIS) remains poorly defined. We compared radiographic correction, operative time, estimated blood loss, and implant cost among different screw density patterns in operatively treated AIS patients.

METHODS

A retrospective observational cohort study of AIS patients who underwent posterior spinal fusion using all-pedicle screw instrumentation was conducted from January 2012 to December 2018. All patients were categorized into three different pedicle screw density groups: the very low density (VLD), the low density (LD), and the high density (HD) group. The comparative effectiveness between each pairwise comparison was performed under the inverse probability of the treatment weighting method to minimize the possible confounders imbalance among treatment groups. The primary endpoints in this study were the degrees of correction and deformity progression at 2 years postoperatively.

RESULTS

A total of 174 AIS patients were included in this study. The adjusted treatment effects demonstrated similar degrees of deformity correction after 2 years in the three treatment groups. However, the VLD and LD group slightly increased the curve progression at 2 years compared to the HD group by 3.9° (p = 0.005) and 3.2° (p = 0.044), respectively. Nevertheless, the limited screw density patterns (VLD and LD) significantly reduced the operative time, estimated blood loss, and implant cost per operated level.

CONCLUSION

The limited pedicle screw pattern (VLD and LD) in relatively flexible AIS spinal deformity correction results in similar coronal and sagittal radiological outcomes while reducing operative time, estimated blood loss, and implant cost compared to the high-density pedicle screw instrumentation.

Pedicle screw placement safety with the aid of patient-specific guides in a case series of patients with thoracic scoliosis

PURPOSE

Pedicle screw (PS) placement in thoracic scoliotic deformities can be challenging due to altered vertebral anatomy; malposition can result in severe functional disability or inferior construct stability. Three-dimensional (3D) printed patient-specific guides (PSGs) have been recently used to supplement other PS placement techniques. We conducted a single-center, retrospective observational study to assess the accuracy of PS placement using PSGs in a consecutive case series of pediatric and adult patients with thoracic scoliosis.

METHODS

We analyzed the data of patients with thoracic scoliosis who underwent PS placement using 3D-printed PSG as a vertebral cannulation aid between June 2013 and July 2018. PS positions were determined via Gertzbein-Robbins (GR) and Heary classifications on computed tomography images. We determined the concordance of actual and preoperatively planned PS positions and defined the technique learning curve using a receiver-operating characteristic (ROC) curve.

RESULTS

We performed 362 thoracic PS placement procedures in 39 consecutive patients. We classified 352 (97.2%), 2 (0.6%), and 8 (2.2%) screws as GR grades 0 (optimal placement), I, and II, respectively. The average instrumented PS entry point offsets on the X- and Y-axes were both 0.8 mm, and the average differences in trajectory between the planned and the actual screw placements on the oblique sagittal and oblique transverse planes were 2.0° and 2.4°, respectively. The learning process was ongoing until the first 12 PSs were placed.

CONCLUSIONS

The accuracy of PS placement using patient-specific 3D templates in our case series exceeds the accuracies of established thoracic PS placement techniques.

Risk Factors for the Drift Phenomenon in O-arm Navigation-Assisted Pedicle Screw Placement during Spinal Deformity Surgery

OBJECTIVE

Intraoperative O-arm navigation systems improve the accuracy of spinal instrumentation placement. However, deviation of the pedicle screw from the guide line might occur. The aim of the present study was to explore the causes of and countermeasures for the drift phenomenon during pedicle screw implantation with the aid of an O-arm three-dimensional navigation system in spinal deformity surgery.

METHODS

This was a retrospective analysis of 341 patients with spinal deformity who underwent O-arm navigation system-assisted pedicle screw placement from July 2015 to June 2019. The patient's general condition, Cobb angle, apical vertebra position, softness index, spinal release status, fixed reference frame position, and distance between the navigation vertebral body and the reference frame were collected and compared by independent-samples t test or Pearson's chi-square analysis. The potential risk factors for the drift phenomenon were identified using binary logistic regression analysis.

RESULTS

The drift phenomenon occurred in 57 patients during the first navigation-assisted pedicle screw placement, for an incidence of 16.7% (57/341). There were significant differences in factors such as the apical vertebra position, softness index, spinal release status, and distance between the vertebral body and the reference frame when the drift phenomenon occurred (P < 0.05). Binary logistic regression analysis showed that the softness index, spinal release status, and distance between the vertebral body and the reference frame when drifting occurred were independent risk factors for the drift phenomenon during O-arm navigation-assisted pedicle screw placement.

CONCLUSION

During the use of an O-arm navigation system to assist with pedicle screw placement, pedicle screws should not be placed away from the reference frame, and spinal osteotomy and release should be performed after pedicle screw placement. In addition, the accuracy of O-arm navigation-assisted pedicle screw placement will be affected more in those with larger softness indices.

Postoperative outcomes of pedicle screw instrumentation for adolescent idiopathic scoliosis with and without a subfascial wound drain: a multicentre randomized controlled trial

AIMS

The aim of this study was to evaluate whether, after correction of an adolescent idiopathic scoliosis (AIS), leaving out the subfascial drain gives results that are no worse than using a drain in terms of total blood loss, drop in haemoglobin level, and opioid consumption.

METHODS

Adolescents (aged between 10 and 21 years) with an idiopathic scoliosis (major curve ≥ 45°) were eligible for inclusion in this randomized controlled noninferiority trial (n = 125). A total of 90 adolescents who had undergone segmental pedicle screw instrumentation were randomized into no-drain or drain groups at the time of wound closure using the sealed envelope technique (1:1). The primary outcome was a drop in the haemoglobin level during first three postoperative days. Secondary outcomes were 48-hour postoperative oxycodone consumption and surgical complications.

RESULTS

All 90 patients were included in the primary outcome analysis (no drain = 43; drain = 47). The mean total postoperative blood loss (intraoperative and drain output) was significantly higher in the group with a subfascial drain than in the no-drain group (1,008 ml (SD 520) vs 631 ml (SD 518); p < 0.001). The drop in haemoglobin level did not differ between the study groups over the postoperative timepoints (p = 0.290). The 48-hour opioid consumption was significantly higher in the no-drain group (2.0 mg/kg (SD 0.9) vs 1.4 (SD 0.6); p = 0.005). Two patients in the no-drain and one patient in the drain group developed a surgical site infection.

CONCLUSION

Leaving the subfascial drain out after pedicle screw instrumentation for AIS is not associated with higher postoperative haemoglobin levels. Patients treated without a subfascial drain needed 30% more opioids during the first 48 hours than those who had a drain.Cite this article: Bone Joint J 2022;104-B(9):1067-1072.

Intraoperative 3D Imaging Reduces Pedicle Screw Related Complications and Reoperations in Adolescents Undergoing Posterior Spinal Fusion for Idiopathic Scoliosis: A Retrospective Study

Widely used surgical treatment for adolescent idiopathic scoliosis (AIS) is posterior spinal fusion using pedicle screw instrumentation (PSI). Two-dimensional (2D) or three-dimensional (3D) navigation is used to track the screw positioning during surgery. In this study, we evaluated the screw misplacement, complications, and need for reoperations of intraoperative 3D as compared to 2D imaging in AIS patients. There were 198 adolescents, of which 101 (51%) were evaluated with 2D imaging and 97 (49%) with 3D imaging. Outcome parameters included radiographic correction, health-related quality of life (HRQOL), complications, and reoperations. The mean age was 15.5 (SD 2.1) years at the time of the surgery. Forty-four (45%) patients in the 3D group and 13 (13%) patients in the 2D group had at least one pedicle screw repositioned in the index operation (p < 0.001). Six (6%) patients in the 2D group, and none in the 3D group had a neurological complication (p = 0.015). Five (5%) patients in the 2D group and none in the 3D group required reoperation (p = 0.009). There were no significant differences in HRQOL score at two-year follow-up between the groups. In conclusion, intraoperative 3D imaging reduced pedicle screw-related complications and reoperations in AIS patients undergoing PSI as compared with 2D imaging.

Pedicle Screw Placement in Adolescent Idiopathic Scoliosis: A Comparison between Robotics Coupled with Navigation versus the Freehand Technique

(1) Background: Robotics coupled with navigation (RAN) is a modern surgical platform shown to increase screw placement accuracy during pediatric scoliosis surgery. Our institution uses a technique which combines the RAN platform for apical pedicle screw placement and the freehand (FH) technique for terminal pedicle screw placement during scoliosis surgery (termed hybrid technique). We question if the complementary use of the RAN technology affects intraoperative outcomes, relative to the FH-only approach. (2) Methods: 60 adolescent idiopathic scoliosis (AIS) patients, ages 11−19 at surgery, who were operated on from 2019 through 2020 by a single surgeon, were retrospectively reviewed. Patients were separated by surgery type (hybrid RAN or FH), matched on demographic and surgical factors, and their intraoperative outcomes were compared statistically. (3) Results: Hybrid RAN patients had more screws placed (p = 0.01) and were of a higher BMI percentile (p = 0.005). Controlling for the number of screws placed, BMI%, and initial curve magnitude, there were no statistical differences in estimated blood loss per screw (p = 0.51), curve correction (p = 0.69), complications (p = 0.52), or fluoroscopy time (p = 0.88), between groups. However, operative time was two minutes longer per screw for hybrid RAN patients (p < 0.001). (4) Conclusions: Hybrid RAN surgeries took longer than FH, but yielded comparable effectiveness and safety as the FH technique during the initial RAN adoption phase.

Surgical outcomes of severe spinal deformities exceeding 100° or treated by vertebral column resection (VCR). Does implant density matter?: an observational study of deformity groupings

STUDY DESIGN

Prospective multicenter international observational study.

OBJECTIVE

To investigate the effect of implant density on clinical outcomes in complex pediatric spine reconstruction. Implant density in spine deformity surgery has been a subject of much debate with some authors advocating higher density for better correction. Few studies have looked at the effect of implant density on severe curves > 100 deg or treated with vertebral column resection (VCR).

METHODS

250/311 pts with 2-year f/u enrolled in the FOX pediatric database from 17 international sites were queried for the impact of implant density and surgical outcomes. Patients were grouped into three implant density categories for comparative analysis Group 1 (density ≤ 1), Group 2 (1 < density < 1.5) and Group 3 (density; 1.5-2).

RESULTS

250 pts: 47 (Grp1)/99 (Grp2) /104 (Grp3); Pre-op age and etiology and curve types were similar in all groups, but body mass index (BMI) was higher in Grp3. Grps 1 and 2 had significantly higher sagittal deformity angular ratio (S-DAR) compared to Grp 3 (p < 0.001). Pre-op Halo Gravity Traction (HGT) was used in 55.3%/44.4%/31.7%, p = 0.017; Grp1/Grp2/Grp3, respectively. Average duration of surgery (min) was higher in Grp3 relative to Grp1 only: 352.5/456.5/515.0, p = 0.0029. Blood loss was similar in all Grps. Rate of VCR, PSO and SPO was similar in all Grps. Pre-op Coronal Cobb avg 96.1/83.6/88.6, p = 0.2342, attained similar correction after HGT (24.6%/27.2%/23.2%, p = 0.4864. Coronal Cobb corrections at 2-year follow-up (FU) were (37.1%/40.3%/53.5%, p = 0.0004). Pre-op sagittal Cobb was (105.4/101.9/75.9, p < 0.01.), achieved similar %correction in HGT (19.1%/22.3%/22.5%, p = 0.6851) and at 2-year FU (39.6%/41.4%/29.8%, p = 0.1916). After adjusting for C-DAR, S-DAR, pre-op coronal and sagittal Cobb, etiology, curve types, age, BMI and number of rods in multivariate analysis, the odds of developing post-operative implant complication was 11 times greater in group 1 compared to group 3 (OR = 11.17,95% CI 2.34-53.32). There was significant improvement in SRS scores in all Grps at 2-year FU.

CONCLUSION

Although higher implant density was observed to be associated with greater curve correction and lower rates of post-operative implant-related complication and revision in heterogeneous case groups, the results may not imply causality of implant density on the outcomes in severe pediatric spine reconstruction.

0.4% incidence of return to OR due to screw malposition in a large prospective adolescent idiopathic scoliosis database

PURPOSE

In contrast to infection and curve progression, return to OR for implant malposition is potentially within the surgeon's control. With increasing surgeon familiarity with freehand/fluoroscopic pedicle screw placement, rates of return to OR due to malposition may have decreased over time. We sought to document the incidence and risk factors for return to OR due to screw malposition in a large cohort of patients with idiopathic scoliosis.

METHODS

AIS patients enrolled in a multicenter prospective registry with minimum 2-year follow-up undergoing PSF between 2003 and 2017 were included. Surgeries with the use of intraoperative CT-guided navigation were excluded. Return to OR due to screw malposition over time was tabulated. Lenke class, age at surgery, year of surgery, height, weight, surgeon and site were evaluated.

RESULTS

2435 patients underwent PSF with non-navigated open pedicle screw instrumentation. Mean age was 14.6 years, mean thoracic curve magnitude was 53°, and mean lumbar was 40°. Patients did not routinely undergo intraoperative or postoperative CT evaluation. There were 10 returns to OR for screw malposition at a mean of 0.83 years postoperatively (range 0.1-3.4 years), for an overall incidence of 0.4%. Of the 14 screws, 10 were thoracic, 7 were left-sided. No association was found between screw malposition and curve size, enrolling site, surgeon, BMI, Lenke class, or age. Five patients had radiculopathy which improved after screw revision. Return to OR for screw malposition changed from 2003 to 2017 (1-0.2%) but this did not reach statistical significance.

CONCLUSION

Although the incidence of asymptomatic malpositioned screws is unknown, the rate of return to the OR for implant malposition overall in this registry was 1 in 250 patients. Recent data suggest the rate has decreased to 1 in 500 patients. Further work may determine whether enabling technologies can reduce the rate, ideally to a "never event".

The prognosis and recovery of major postoperative neurological deficits after corrective surgery for scoliosis : an analysis of 65 cases at a single institution

AIMS

The outcome following the development of neurological complications after corrective surgery for scoliosis varies from full recovery to a permanent deficit. This study aimed to assess the prognosis and recovery of major neurological deficits in these patients, and to determine the risk factors for non-recovery, at a minimum follow-up of two years.

METHODS

A major neurological deficit was identified in 65 of 8,870 patients who underwent corrective surgery for scoliosis, including eight with complete paraplegia and 57 with incomplete paraplegia. There were 23 male and 42 female patients. Their mean age was 25.0 years (SD 16.3). The aetiology of the scoliosis was idiopathic (n = 6), congenital (n = 23), neuromuscular (n = 11), neurofibromatosis type 1 (n = 6), and others (n = 19). Neurological function was determined by the American Spinal Injury Association (ASIA) impairment scale at a mean follow-up of 45.4 months (SD 17.2). the patients were divided into those with recovery and those with no recovery according to the ASIA scale during follow-up.

RESULTS

The incidence of major deficit was 0.73%. At six-month follow-up, 39 patients (60%) had complete recovery and ten (15.4%) had incomplete recovery; these percentages improved to 70.8% (46) and 16.9% (11) at follow-up of two years, respectively. Eight patients showed no recovery at the final follow-up. The cause of injury was mechanical in 39 patients and ischaemic in five. For 11 patients with misplaced implants and haematoma formation, nine had complete recovery. Fisher's exact test showed a significant difference in the aetiology of the scoliosis (p = 0.007) and preoperative deficit (p = 0.016) between the recovery and non-recovery groups. A preoperative deficit was found to be significantly associated with non-recovery (odds ratio 8.5 (95% confidence interval 1.676 to 43.109); p = 0.010) in a multivariate regression model.

CONCLUSION

For patients with scoliosis who develop a major neurological deficit after corrective surgery, recovery (complete and incomplete) can be expected in 87.7%. The first three to six months is the time window for recovery. In patients with misplaced implants and haematoma formation, the prognosis is satisfactory with appropriate early intervention. Patients with a preoperative neurological deficit are at a significant risk of having a permanent deficit. Cite this article: Bone Joint J 2022;104-B(1):103-111.

Anatomical changes in vertebra in dystrophic scoliosis due to neurofibromatosis and its implications on surgical safety

STUDY DESIGN

Detailed radiological analysis by multimodality imaging.

OBJECTIVE

To document anatomical changes jeopardizing instrumentation safety in Neurofibromatosis deformity correction surgeries.

MATERIALS AND METHODS

The apical and 3 adjacent vertebral segments above and below amounting to 70 segments in 10 NF scoliosis were studied by radiographs, CT and MRI. The changes in lamina, pedicle and vertebral body that could jeopardize pedicle screw and sublaminar wire placement were documented and changes were appropriately classified.

RESULTS

Extensive anatomical changes were noted. These changes were more severe at the apex and independent of the curve severity. Both laminae were normal in only 36 (Type 1), rest had either gross asymmetry in length and shape (Type 2; 21) or also in sloping (Type 3; 13). Of the 140 pedicles, normal pedicles were found only in 48 (Type 1); while they were divergent (Type 2; 4) or abnormally elongated with only thinning (Type 3a; 26); or with sclerosis (3b; 34); or very curved and wavy (3c; 23) and even fractured or indistinct (Type 4; 5). It was notable that 92 of the 140 pedicles were unsuitable for pedicle screws. A unique phenomenon of body drift was identified in 29 segments which could jeopardize screw placement and rib dislocation into the canal was found in 18 segments.

CONCLUSION

Gross anatomical changes jeopardizing both sublaminar wire strength and trajectory of pedicle screws were common in NF and independent of curve severity. Therefore, detailed preoperative assessment and planning by a 3D CT are essential.

Loss of correction in cubitus varus deformity after osteotomy

We aimed to investigate the rate of loss of correction and the factors thereof in pediatric patients undergoing osteotomy for treatment of cubitus varus deformity.Between July 2008 and July 2017, we treated 30 patients who underwent osteotomy for cubital varus. We compared the preoperative and postoperative clinical and imaging findings, including the H-Cobb and Baumman angles, in all patients. Postoperative evaluation was performed by telephonic interviews.Our patients consisted of 17 males and 13 females. The mean age was 75 months. At the first follow-up, approximately 80% of patients had experienced a loss of correction of the humerus-cobb angle (H-Cobb angle); at the second follow-up, the incidence was 83%. Meanwhile, 57% and 43% of patients experienced a loss of correction of the Baumman angle at the first and second follow-ups, respectively. The average interval between the first and second follow-ups was 24 days, and the mean loss in the H-Cobb angle was 2.4°. There was a significant difference between the H-Cobb angles as measured before and after surgery (P < .05). There was no significant difference between the H-Cobb angles of the affected side and the contralateral healthy elbow at the third postoperative follow-up; however, there was a significant difference between the Baumman angle between before and after surgery (P < .05). The Baumman angles as measured at the second and third postoperative follow-ups differed significantly from those of the contralateral healthy elbow joint. According to the survival curve analysis, the median survival times of the H-Cobb and Baumman angles were 27 and 34 months, respectively.The postoperative loss of the 2 angles occurred mainly during the first and second follow-up periods. Therefore, patient follow-up is particularly important in the period directly following the operation. Additional measures may be necessary to avoid rapid angle loss.

3D printed templates improve the accuracy and safety of pedicle screw placement in the treatment of pediatric congenital scoliosis

Background

Three-dimensional (3-D) printed guidance templates are being increasingly used in spine surgery. The purpose of this study was to determine if 3D printed navigation templates can improve the accuracy of pedicle screw placement and decrease the complication rate compared to freehand screw placement in the treatment of children with congenital scoliosis.

Methods

The records of pediatric patients with congenital scoliosis treated at our hospital from January 2017 to January 2019 were retrospectively reviewed. Patients were divided into those where a 3D printed guidance templated was used and those in which the freehand method was used for pedicle screw placement. The accuracy rate of pedicle screw placement, surgical outcomes, and complications were compared between groups.

Results

A total of 67 children with congenital scoliosis were included (43 males and 24 females; mean age of 4.13 ± 2.66 years; range, 2–15 years). There were 34 children in the template-assisted group and 33 in the freehand group. The excellent accuracy rate of pedicle screw placement was significantly higher in the template-assisted group (96.10% vs. 88.64%, P = 0.007). The main Cobb angle and kyphosis angle were similar between the 2 groups preoperatively and postoperatively (all, P > 0.05), and in both groups both angles were significantly decreased after surgery as compared to the preoperative values (all, P < 0.001). The degree of change of the Cobb angle of the main curve and kyphosis angle were not significantly different between the 2 groups. There were no postoperative complications in the template group and 4 in the freehand group (0% vs. 12.12%; P = 0.009). All 4 patients with complications required revision surgery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04892-4.

Intraoperative Use of Robotics With Navigation for Pedicle Screw Placement in Treatment of Pediatric High-grade Spondylolisthesis: A Preliminary Report

BACKGROUND

Accurate pedicle screw placement is critical to surgically correct pediatric high-grade spondylolisthesis (HGS). The recent advent of robotics coupled with computer-assisted navigation (RAN) may represent a novel option to improve surgical outcomes of HGS, secondary to enhanced pedicle screw placement safety. This series presents the HGS-RAN technique adopted by our site, describing its surgical outcomes and feasibility.

METHODS

Consecutive patients with a diagnosis of HGS (Meyerding grade III to V), operated on using RAN from 2019 to 2020 at a single-center were reviewed. Demographics, screw accuracy, sagittal L5-S1 parameters, complications, and perioperative outcomes were described. All patients were treated with instrumentation, decompression, posterior lumbar interbody fusion, and reduction. Robotic time included anatomic registration to end of screw placement. Screw accuracy-defined as a screw placed safely within the planned intrapedicular trajectory-was characterized by the Gertzbein-Robbins system for patients with additional 3-dimensional imaging.

RESULTS

Ten HGS patients, with an average age of 13.7 years old, were included in the series. All 62 screws were placed without neurological deficit or complication. Seven patients had additional 3-dimensional imaging to assess screw accuracy (42 of 62 screws). One hundred percent of screws were placed safely with no pedicle breaches (Gertzbein-Robbins-grade A). Thirty screws (48%) were placed through separate incisions that were percutaneous/transmuscular and 32 screws (52%) were inserted through the main incision. There were statistically significant improvements in L5 slippage (P=0.002) and lumbosacral angle (P=0.002), reflecting successful HGS correction. The total median operative time was 324 minutes with the robotic usage time consuming a median of 72 minutes. Median estimated blood loss was 150 mL, and length-of-stay was a median 3 days.

CONCLUSIONS

This case-series demonstrates that RAN represents a viable option for HGS repair, indicated by high screw placement accuracy, safety, and L5-S1 slippage correction. Surgeons looking to adopt an emerging technique to enhance safety and correction of pediatric HGS should consider the RAN platform.

LEVEL OF EVIDENCE

Level IV-therapeutic study.

Anterior versus posterior fusion surgery in idiopathic scoliosis: a comparison of health-related quality of life and radiographic outcomes in Lenke 5C curves - results from the Swedish spine registry

PURPOSE

To compare health-related quality of life and radiographic outcomes in patients treated with either anterior or posterior fusion surgery for Lenke 5C type idiopathic scoliosis.

METHODS

We used data from the Swedish spine registry and identified 59 patients with idiopathic scoliosis treated with fusion for Lenke 5C type curves; 27 patients underwent anterior surgery and 32 underwent posterior surgery. All patients had pre- and postoperative radiographic data and postoperative clinical data at a minimum of two years after surgery. Patient-reported outcomes measures included the Scoliosis Research Society (SRS)-22r, EuroQoL 5 dimensions 3 levels (EQ-5D-3L), EQ-visual analogue scale (VAS) and VAS for back pain. Radiographic assessment included measurement of the angle of the major curve, disc angulation below the lowest instrumented vertebra, curve flexibility, rate of curve correction, differences in sagittal parameters, number of fused vertebrae and length of fusion.

RESULTS

The mean age at surgery was 16 years in both groups. The mean follow-up time was 3.8 years. There were no significant differences in the SRS-22r score and EQ-5D-3L index at follow-up (all p ≥ 0.2). Postoperatively, both the anterior and posterior fusion group demonstrated a significant correction of the major curve (p ≤ 0.001) with no significant difference of the correction rate between the groups (p = 0.4). The posterior fusion group had shorter operative time (p < 0.001) and higher perioperative blood loss (p = 0.004) while the anterior group had lower number of fused vertebrae ( p< 0.001).

CONCLUSION

The type of surgical approach for Lenke 5C curves is not associated with differences in health-related quality of life, despite the lower number of fused vertebrae after anterior surgery.

LEVEL OF EVIDENCE

III.

The Use of Robotics Coupled With Navigation for Pediatric Congenital Spine Deformity

Background: Spinal instrumentation in children with congenital spine deformity poses challenges to the surgeon, given the small patient size and the anomalous anatomy often encountered. Purpose: We aimed to investigate the accuracy of screw placement when robotics coupled with real-time navigation was used for surgical treatment of pediatric congenital spine deformity at 1 institution. Methods: We conducted a retrospective search of our institution's database for all patients younger than 18 years of age with congenital spine deformity who were treated with the robotics surgical platform coupled with navigation between June 2019 and December 2020. We recorded data on demographics, location and type of anomaly, procedure performed, and intraoperative variables related to robotics and navigation. We reviewed the images of patients who had intraoperative 3-dimensional imaging or postoperative computed tomographic scans to determine the accuracy of screw placement using the Gertzbein-Robbins scale. Results: In 14 patients identified, a total of 95 screws were attempted, with 94 successfully placed using robotics coupled with navigation. There were no noted screw-related complications (neurologic or visceral) and no return to the operating room for screw malposition. Conclusion: Patients with congenital spine deformity present potentially unique challenges due to variant anatomy. This retrospective series suggests that robotics coupled with navigation for congenital spine deformity correction in the pediatric population may aid in accurate screw placement and reduce complication rates. More rigorous study is warranted.

Nonaccidental Trauma Managed with Open Spinal Fixation and Instrumentation and a Review of the Literature

Nonaccidental trauma (NAT), causing spinal injury is rare and occurs in up to 3% of cases. Management of these injuries is typically conservative, and thus surgical management is not widely reported in the literature. In this case report, we presented three patients to review the effectiveness of spinal instrumentation and posterior fusion in pediatric patients due to NAT. All patients recovered well and were neurologically intact at last follow-up with no postprocedural complications noted. Spinal arthrodesis is a safe, effective way to manage spinal injuries due to NAT in cases of fracture-dislocation, distraction injuries, as well as cases involving neurologic compromise.

Screw Malposition: Are There Long-term Repercussions to Malposition of Pedicle Screws?

BACKGROUND/INTRODUCTION

Pedicle screws have long been part of the continued advancements in spine surgery. Despite the many techniques that have been devised for their safe placement, malposition of screws continues to occur. Studies have evaluated the possible safe limits of screw malposition, and have given some insight on anatomic variation in spinal deformity. Review of the literature reveals several cases of deleterious long-term sequelae of malpositioned screws.

DISCUSSION

With the current experience, proposed recommendations are provided to detect and avoid the potential long-term sequelae. Though the literature has helped to define possible concerning screws, there are no good studies predicting long-term risk.

CONCLUSION

Improvements in technology and techniques, advancements in intraoperative confirmation and postoperative surveillance, studies that assist risk stratification, and expert consensus evaluations will help guide surgeons in their decision for addressing misplaced screws.

Efficacy of polyester bands placed under the transverse vertebral process for the correction of adolescent idiopathic scoliosis : A case series of 105 patients with a minimum of 24 months follow-up

PURPOSE

To report an original technique for the surgical correction of adolescent idiopathic scoliosis (AIS) based on hybrid construct using polyester bands placed under the thoracic transverse processes.

METHODS

We reviewed 105 patients operated between 2013 to 2017 for AIS with a minimum of 2 years follow-up. Clinical and radiological data, including 2D measurements of scoliosis parameters preoperatively, and at 3- and 24-months postoperatively were analyzed. Radiological analysis was performed by two independent observers using KEOPS (Smaio, Lyon-France, CE 2014) database.

RESULTS

Mean age was 14.6 ± 2 years. Mean follow-up was 23.7 ± 1.2 months. Most curves were classified as Lenke-1 (78%). The average number of vertebra involved in the construct was 10.9 ± 1.3 (range 7-13). A mean of 12.8 implants were used per construct (mean implant density 0.59). The number of subtransverse bands placed averaged 3 (range 1-5 bands). The mean frontal Cobb angle decreased from 57.9 to 21.2 ° (p < 0.05) postoperatively. The average T4-T12 kyphosis increased from 20.2°to 32.4° (p < 0.05) postoperatively and no loss of correction was observed at 2 years follow-up. We encountered one case of transverse process fracture intraoperativley. No neurological complications were observed. In the postoperative period, 4 cases were diagnosed with distal junctional failure, three of which required an extension of the construct, while the fourth case was treated by bracing.

CONCLUSIONS

The use of subtransverse band is an efficient and safe method for the surgical correction of AIS. This technique incorporates technical ease (minimal risk of neurological injury), provides good frontal correction and restores thoracic kyphosis. Results are maintained over a two-year period.

Higher pedicle screw density does not improve curve correction in Lenke 2 adolescent idiopathic scoliosis

Purpose

Higher pedicle screw density posterior spinal fusion (PSF) constructs have not been shown to result in improved curve correction in Lenke 1 and 5 adolescent idiopathic scoliosis (AIS) but do increase cost. The purpose of this study questioned whether higher screw density constructs improved curve correction and maintenance of correction in Lenke 2 AIS. Secondary goals were to identify predictive factors for correction and postoperative magnitude of curves in Lenke 2 AIS.

Methods

We identified patients 11 to 17 years old who underwent primary PSF for Lenke 2 AIS between 2007 and 2017 who had minimum follow-up of 2 years. Demographic and radiographic data were collected to perform regression and elimination analysis.

Results

Thirty patients (21 females, 9 males) were analyzed. Average age and SD at time of surgery was 14.0 ± 1.8 years (range, 11–17 years), and median follow-up was 2.8 years (IQR 2.1–4.0 years). Implant density did not predict final postoperative curve magnitude. Predictors of final postoperative curve magnitude were sex and preoperative curve magnitude. Predictors of percentage of correction of major curve were sex and age at the time of surgery. Predictors of final postoperative thoracic kyphosis were sex and percent flexibility preop. Females had lower final postoperative major curve magnitude, a higher percent curve correction, and lower postoperative thoracic kyphosis.

Conclusions

Increased implant density is not predictive of postoperative curve magnitude in Lenke 2 AIS. Predictors of postoperative curve magnitude are sex and preoperative curve magnitude.

Level of evidence

Level III, retrospective observational

Use of intraoperative navigation for posterior spinal fusion in adolescent idiopathic scoliosis surgery is safe to consider

PURPOSE

The use of image-guided stereotactic navigation is increasing in use in treating AIS; however, no studies have investigated perioperative outcomes and short-term adverse events compared with non-navigated procedures. The aim of the present study is to use a large national pediatric database to assess the rate of utilization of intraoperative navigation in pediatric patients undergoing posterior spinal fusion for adolescent idiopathic scoliosis (AIS) and to compare thirty-day outcomes of navigated vs. non-navigated surgery.

METHODS

The NSQIP-Pediatric database was queried for cases of posterior fusion for AIS. Patients were stratified by whether or not a concurrent code for stereotactic navigation was used (CPT 61,783). Year of procedure, demographics, comorbidities, operative variables and perioperative adverse outcomes were abstracted and assessed using univariate and multivariate analysis.

RESULTS

Overall, 12,739 non-navigated patients and 340 navigated patients were identified. The use of navigation increased from 0.5% of cases in 2012 to 5.2% of cases in 2018. Demographics, comorbidities, and number of levels fused did not differ between navigated and non-navigated patients. Navigated cases were on average 41 min longer than non-navigated cases (268.6 vs. 309.6 min p < 0.001), with 9.84% more cases requiring transfusion (65.0% vs 75.6%, p < 0.001). Hospital stay for navigated cases was an average of 0.4 days shorter (3.9 days vs 4.3 days, p = 0.001). On multivariate analysis, navigated cases had higher odds of prolonged surgery (OR = 2.13, p < 0.001) and lower odds of prolonged length of stay (OR = 0.28, p < 0.001).

CONCLUSION

Although the use of navigation for AIS posterior fusion was associated with longer operative time, post-operative hospital stay was shorter and other perioperative adverse outcomes were not significantly different between groups.

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.

Two AIS spine surgeries on the same day by the same surgeon: is performance and outcome the same for the second patient?

STUDY DESIGN

Retrospective case-controlled study.

OBJECTIVES

To analyze the overall performance and outcome of two-a-day surgery days for adolescent idiopathic scoliosis (AIS). As a method to improve efficiency and operating room utilization, some surgeons are now performing two surgeries for AIS in a single day.

METHODS

A prospectively collected series of AIS patients who underwent posterior spinal fusion on the same day as a second AIS patient by the same surgeon and surgical team were retrospectively reviewed. Patients who underwent same-day surgery (SD) were grouped according to whether they were the first (SD1) or second (SD2) case of the day and were matched (M1 and M2) by surgeon, curve magnitude, Lenke classification, and fusion levels. Comparisons were made: SD1 vs. SD2, SD1 vs. M1, and SD2 vs. M2.

RESULTS

There were 56 patients, with no differences between groups in age, gender, BMI, or curve magnitude (66° vs. 62° vs. 65° vs. 63°). Surgical time was shorter for the SD1 group (17.2 min/level) compared to M1 (20.5 min/level) for a 15% operative time reduction of 44 min (p = 0.008). There were no differences between the groups in curve correction (65.8% vs. 62.8% vs. 66.1% vs. 58.5%), estimated blood loss (EBL), length of stay, or complication rate. One SD2 patient had a malpositioned screw that required revision. There were no other complications.

CONCLUSIONS

When performing two AIS surgeries on the same day, surgical time was reduced by 44 min, or 15%, on the first case compared to a matched control. This may be a reflection of the team moving along more efficiently, given the full operative day scheduled. The performance measures of curve correction, EBL, complications, and length of stay did not decline in this new model, and no increased incidence of complications was seen.

Willingness to enroll in a surgical randomized controlled trial: patient and parent preferences regarding implant density for adolescent idiopathic scoliosis fusion

STUDY DESIGN

Prospective survey of adolescent idiopathic scoliosis (AIS) patients/parents with surgical magnitude curves.

OBJECTIVE

We hypothesized that patients and families considering fusion surgery would be willing to enroll in a randomized controlled trial (RCT) evaluating the effect of number of implants on curve correction. Surgical RCTs are infrequently performed, particularly in a pediatric population. Parental willingness to enroll affects both study design and trial feasibility. The Minimize Implants Maximize Outcomes (MIMO) Clinical Trial proposes to randomize patients to more versus fewer screws (high or low density) for Lenke 1A curve patterns, but it is unclear whether families and patients are willing to enroll in such a trial.

METHODS

This study was undertaken at 4 of the 14 sites participating in the MIMO Clinical Trial. AIS patients with Cobb > 45° were included. Implant density is defined as screws per level fused. Patients and families reviewed the MIMO education module describing proposed advantages and disadvantages of high (> 1.8) vs. low (< 1.4) density screw constructs and completed a custom survey regarding their preferences about the trial.

RESULTS

159 individuals were surveyed (78 families), including 82 parents/guardians, and 77 patients. Of those surveyed, 95% mostly or completely understood the trial (range 47-78%), and 63% agreed to enroll. Parents and patients who completely understood the trial were significantly more likely to enroll.

CONCLUSION

Randomization in the MIMO Trial was acceptable to the majority (63%) of patients and parents. Clear patient and parent education materials and access to the surgeon may facilitate enrollment in the trial. Parents afforded the child much autonomy when considering enrollment, although most families agree both child and parent should be in agreement before entering the trial.

LEVEL OF EVIDENCE

II.

Personalized Three-Dimensional Printing Pedicle Screw Guide Innovation for the Surgical Management of Patients with Adolescent Idiopathic Scoliosis

OBJECTIVE

To assess the safety and efficacy of patient-specific three-dimensional (3D) rapid-prototype printing technology for pedicle screw insertion in patients with adolescent idiopathic scoliosis (AIS).

METHODS

The 3D pedicle screw guides were produced after selecting the fixation points for all individual levels to be used intraoperatively. Preoperative computed tomography images recreated 3D bone models of each vertebra specific to each patient. Safe pedicle trajectories were determined in all 3 planes on these models. 3D printed guides were modeled according to these trajectories and manufactured with a biocompatible material. Postoperatively, all screws were evaluated and scored with computed tomography as class 1 (accurate), class 2 (inaccurate), or class 3 (deviated). The mean angle between the inserted pedicle screw and the intended trajectory, and the mean distance between the central longitudinal axis of a screw and pedicle were also measured.

RESULTS

A total of 134 screws were inserted. On the concave and convex sides, the mean medial malposition was 0.5 ± 0.8 and 0.4 ± 0.6 mm, the mean lateral malposition was 1.4 ± 2.3 and 0.8 ± 1.3 mm, angle between the inserted pedicle screw and the intended trajectory was 4.2 ± 4.6 and 4.3° ± 6.0°, and distance between the central longitudinal axis of a screw and pedicle was 1.5 ± 2.1 and 0.9 ± 1.2 mm, respectively. A total of 117 screws were regarded as class 1, 14 as class 2, and 3 as class 3. Of all screws inserted, 92.5% achieved positional accuracy. There were no screw-related complications.

CONCLUSIONS

This is one of the initial reports to note the novel design and implementation of patient-specific 3D pedicle screw guides for adolescent idiopathic scoliosis surgery. Our pilot study shows that the use of these low-cost personalized 3D guides is completely safe and effective in both convex and concave sides of the curves.

Standard and magnetically controlled growing rods for the treatment of early onset scoliosis

Distraction based spinal instrumentation represents the most common and standard surgical technique to correct early onset scoliosis (EOS), i.e., scoliosis which has been diagnosed before the age of 10 years. Surgical treatment of EOS aims at controlling spinal deformity while maintaining spinal growth which is mandatory for the development of normal lung capacity. To achieve these goals the spinal instrumentation needs to be distracted to facilitate spinal growth during treatment. Distraction can be obtained by repeated surgical lengthenings (traditional growing rods, TGRs) or using magnetically controlled growing rods (MCGRs), which can be lengthened using external remote controller on an outpatient basis. The outcomes of TGR instrumentation for EOS are well described with follow-up until skeletal maturity: normal spinal growth can be maintained, 40-50% of the scoliosis can be corrected, but there is an over 50% risk of complications including deep wound infection, rod failure, and instrumentation pull-out. MCGR instrumentation may reduce the risk of wound related complications, provides similar deformity correction, but may not provide as much spinal growth. Metallosis around the instrumentation necessitates MCGR removal and definitive final instrumented fusion at the end of growth friendly management. Even severe EOS can be treated using distraction based spinal instrumentation.

The Accuracy of 3D Printing Assistance in the Spinal Deformity Surgery

Background

The pedicle screw is one of the main tools used in spinal deformity correction surgery. Robotic and navigated surgeries are usually used, and they provide superior accuracy in pedicle screw placement than free-hand and fluoroscopy-guided techniques. However, their high cost and space limitation are problematic. We provide a new solution using 3D printing technology to facilitate spinal deformity surgery.

Methods

A workflow was developed to assist spinal deformity surgery using 3D printing technology. The trajectory and profile of pedicle screws were determined on the image system by the surgical team. The engineering team designed drill templates based on the bony surface anatomy and the trajectory of pedicle screws. Their effectiveness and safety were evaluated during a preoperative simulation surgery. The surgery consisted in making a pilot hole through the drill template on a computed tomography- (CT-) based, full-scale 3D spine model for every planned segment. Somatosensory evoke potential (SSEP) and motor evoke potential (MEP) were used for intraoperative neurophysiological monitoring. Postoperative CT was obtained 6 months after the correction surgery to confirm the screw accuracy.

Results

From July 2015 to November 2016, we performed 10 spinal deformity surgeries with 3D printing technology assistance. In total, 173 pedicle screws were implanted using drill templates. No notable change in SSEP and MEP or neurologic deficit was noted. Based on postoperative CT scans, the acceptable rate was 97.1% (168/173). We recorded twelve pedicle screws with medial breach, six with lateral breach, and five with inferior breach. Medial breach (12/23) was the main type of penetration. Lateral breach occurred mostly in the concave side (5/6). Most penetrations occurred above the T8 level (69.6%, 16/23).

Conclusion

3D printing technology provides an effective alternative for spinal deformity surgery when expensive medical equipment, such as intraoperative navigation and robotic systems, is unavailable.

The correlations between the anchor density and the curve correction of adolescent idiopathic scoliosis surgery

Background

The optimal anchor density in adolescent idiopathic scoliosis (AIS) surgery to achieve good curve correction remains unclear. The purpose of the study is to analyze the correlations between three-dimensional curve correction and anchor density in the pedicle screw-based posterior fusion of AIS.

Methods

One hundred and twenty-seven AIS patients receiving primary posterior fusion with pedicle screw instrumentation were retrospectively reviewed. Anchor density (AD) was defined as the screws number per fused spinal segment. The correlations between three-dimensional curve correction radiographic parameters and anchor density were analyzed with subgroup analysis based on different curve types, curve magnitudes, and curve flexibilities. The differences of curve correction parameters between the low-density (AD ≤1.4), middle-density (1.4 < AD ≤1.7) and high-density (AD > 1.7) groups were also calculated. Independent t-test, analysis of variance (ANOVA), and Pearson’s correlation coefficient were used for statistical analysis.

Results

There were no correlations between the anchor density and the coronal curve correction or apical vertebral rotation (AVR) correction. In the sagittal plane, mild positive correlations existed between anchor density and thoracic kyphosis correction in all patients (r = 0.27, p = 0.002). Subgroup analysis revealed similar mild positive correlations in Lenke 1 (r = 0.31, p = 0.02), Lenke 1–3 (r = 0.27, p = 0.01), small curves (40°-60°, r = 0.38, p <  0.001), and flexible curves (flexibility > 40%, r = 0.34, p = 0.01).

There were no differences between low-density (mean 1.31), middle-density (mean 1.55), and high-density (mean 1.83) in terms of coronal or axial curve correction parameters. Low-density group has longer fused level (mean difference 2.14, p = 0.001) and smaller thoracic kyphosis correction (mean difference 9.25°, p = 0.004) than high-density group.

Conclusion

In our study, the anchor density was not related to coronal or axial curve corrections. Mild positive correlations with anchor density were found in thoracic kyphosis correction, especially in patients with smaller and flexible curves. Low anchor density with longer fusion level achieves similar curve corrections with middle or high anchor density in adolescent idiopathic scoliosis surgery.

Back Pain and Quality of Life After Surgical Treatment for Adolescent Idiopathic Scoliosis at 5-Year Follow-up: Comparison with Healthy Controls and Patients with Untreated Idiopathic Scoliosis

BACKGROUND

Posterior spinal fusion with pedicle screws is the gold-standard treatment for adolescent idiopathic scoliosis (AIS); however, it is unclear whether this procedure results in improved long-term back pain and health-related quality of life compared with patients not surgically treated for AIS. The aim of the present study was to evaluate back pain and quality of life in surgically managed patients with a minimum follow-up of 5 years compared with patients with untreated AIS and a healthy control group.

METHODS

Fifty-five consecutive adolescent patients who underwent posterior pedicle screw instrumentation for AIS by a single orthopaedic surgeon were prospectively enrolled. At a minimum of 5 years postoperatively, 49 patients completed Scoliosis Research Society (SRS)-24 questionnaires, and data on reoperation were collected. Pain and quality-of-life parameters were compared with those of 49 age and sex-matched patients with untreated AIS and 49 healthy controls.

RESULTS

The major curve averaged 53° preoperatively and 12° at 2 years postoperatively. One reoperation (pedicle screw removal) was needed because of a new neurological deficit (transient). The SRS-24 pain, function, and total scores improved significantly from preoperatively to 5 years postoperatively (all p ≤ 0.016), with pain scores improving from 4.0 to 4.3 (p = 0.003). There was no association between pain scores and the preoperative major curve, instrumentation below L1, or postoperative rib hump. The surgical treatment group had significantly better pain, activity, and self-image domain scores at 5 years postoperatively compared with the untreated AIS group (all p ≤ 0.014), and similar pain, self-image, and activity domain scores compared with the healthy control group; however, function scores were significantly lower among patients in the surgical treatment group (p < 0.001).

CONCLUSIONS

Patients who underwent posterior spinal fusion with pedicle screws experienced improved back pain and health-related quality of life compared with patients with untreated AIS. Patients in the surgical treatment group had similar health-related quality of life to that of the healthy control group, except for function, which was significantly lower.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Does Three-dimensional Printing Plus Pedicle Guider Technology in Severe Congenital Scoliosis Facilitate Accurate and Efficient Pedicle Screw Placement?

BACKGROUND

Three-dimensional (3-D) printing offers the opportunity to create patient-specific guides for pedicle screw placement based on CT-generated models. This technology might allow for more-accurate placement of pedicle screws in patients with severe congenital scoliosis who have rotated vertebrae and small pedicles, but to our knowledge, this premise has not been tested.

QUESTIONS/PURPOSES

(1) Is the use of 3-D printing and pedicle guider technology as or more accurate than the use of the freehand technique for pedicle-screw placement in patients with severe congenital scoliosis? (2) Does surgical time differ with the use of these guiders? (3) Are complications less common in patients treated with this new approach to pedicle-screw placement?

METHODS

A prospective controlled study was conducted of patients with severe congenital scoliosis (major curve ≥ 90°) from June 2016 to June 2018. During this period, we treated 93 patients with congenital scoliosis; 32 had severe scoliosis with a major curve ≥ 90°. The patients were divided into a pedicle guider group (n = 15) and a control group (n = 17) based on their willingness to use pedicle guider technology, which was considered a research technology. With the numbers available, there were no between-group differences in terms of age, sex, BMI, or parameters related to curve severity or flexibility, and all patients in both groups had severe curves. Preoperative and postoperative low-dose CT scans were performed in the two groups. In the pedicle guider group, custom software was used to design the pedicle guider, and a 3-D printer was used to print a physical spinal model and pedicle guiders. The pedicle guiders were tested on the surface of the physical spinal model before surgery to ensure proper fit, and then used to assist pedicle screw placement during surgery. A total of 244 screws were implanted with the help of 127 pedicle guiders (254 guiding tunnels) during surgery in the PG group. Five predesigned pedicle guiders were abandoned due to an unstable match, and the success rate of assisted screw placement using a pedicle guider was 96% (244 of 254). The freehand technique was used in the control group, which relied on anatomic localization to place pedicle screws. The accuracy of pedicle screw placement was evaluated with CT scans, which revealed whether screws had broken through the pedicle cortex. We compared the groups in terms of accuracy (defined as unanticipated breaches less than 2 mm), surgical time, time to place pedicle screws, and screw-related complications.

RESULTS

A higher proportion of the screws placed using pedicle guider technology were positioned accurately than were in the control group (93% [227 of 244] versus 78% [228 of 291]; odds ratio, 3.69 [95% CI, 2.09-6.50]; p<0.001). With pedicle guider use, operative time (296 ± 56 versus 360 ± 74; 95% CI, -111 to -17; p = 0.010), time to place all screws (92 ± 17 versus 118 ± 21; 95% CI, -39 to -12; p = 0.001), and mean time to place one screw (6 ± 1 versus 7 ± 1; 95% CI, -2 to 0; p = 0.011) decreased. One patient in the pedicle guider group and four in the control group experienced screw-related complications; the sample sizes and small number of complications precluded statistical comparisons.

CONCLUSIONS

In this small, preliminary study, we showed that the accuracy of the surgical technique using spinal 3-D printing combined with pedicle guider technology in patients with severe congenital scoliosis was higher than the accuracy of the freehand technique. In addition, the technique using pedicle guider technology appeared to shorten operative time. If these findings are confirmed in a larger study, pedicle guider technology may be helpful for situations in which intraoperative CT or O-arm navigation is not available.

LEVEL OF EVIDENCE

Level II, therapeutic study.

Pedicle screw accuracy in clinical utilization of minimally invasive navigated robot-assisted spine surgery

In the emerging field of robot-assisted spine surgery, the radiographic evaluation of pedicle screw accuracy in clinical application is an area of high interest. This study describes the pedicle screw accuracy of the first 56 consecutive cases in which navigated robotic assistance was used in a private practice clinical setting. A retrospective, Institutional Review Board-exempt review of the first 56 navigated robot-assisted spine surgery cases was performed. Pedicle screw malposition, reposition, and return to operating room (OR) rates were collected. A CT-based Gertzbein and Robbins system (GRS) was used to classify pedicle screw accuracy. In the first 56 robotic cases, 356 total pedicle screws were placed. Eight screws were placed without the robot due to surgeon discretion. Of the 348 pedicle screws inserted by navigated robotic guidance, only 2.6% (9/348) were repositioned, resulting in a 97.4% (339/348) successful screw placement rate. The average age was 64, and 48% were female. Average body mass index was 31 kg/m². Based on the GRS CT-based grading, 97.7% (340/348) were graded A or B, 1.7% (6/348) screws were graded C, and only 0.6% (2/348) of screws were graded D. Two complications, explantation of interbody and vacuum-assisted wound closure, were reported as requiring a return to the OR, but these were not related to robotic guidance or pedicle screws. This study demonstrated a high level of accuracy (97.7%) in the first 56 cases using navigated, robot-assisted surgery based on the GRS. There were two non-screw-related complications requiring return to the operating room.

Intraoperative Computed Tomography-Guided Navigation for Pediatric Spine Patients Reduced Return to Operating Room for Screw Malposition Compared With Freehand/Fluoroscopic Techniques

PURPOSE

Placement of pedicle screws can be performed using freehand/fluoroscopic technique or intraoperative computed tomography (CT)-guided navigation. We sought to compare screw malposition and return to operating room (OR) for pedicle screw malposition for screws placed with and without CT-guided navigation.

METHODS

This study was a single-center retrospective comparative study. All patients younger than 18 years with minimum two-year follow-up who underwent pedicle screw instrumentation between 2009 and 2015 were included. Institutional review board approval was obtained and patient charts were reviewed for patient demographics and surgical outcomes. If available, incidental CTs following the index surgery were reviewed to assess screw position.

RESULTS

A total of 217 patients underwent spinal instrumentation. Overall, 112 patients had pedicle screws placed using fluoroscopic guidance, whereas 105 patients had screws placed using low-dose intraoperative CT-guided navigation (O-arm; Medtronics). Of the total cohort, 107 (49.3%) patients had adolescent idiopathic scoliosis, and the remainder had neuromuscular, tumor, congenital, or other diagnoses. Patients in each group had a similar number of levels fused (fluoroscopic = 10.9 vs. CT navigation = 9.8, p = .06). There was no difference in total estimated blood loss (1,127 vs. 1,179 mL, p = .63) or in blood loss per level fused (133.7 vs. 146.6 mL, p = .47). Patients with screws placed using fluoroscopic guidance had a shorter total operative time (441 vs. 468 minutes, p = .04); however, there was no difference when controlling for number of levels fused (58.3 vs. 61.5 minutes/level, p = .63). Postoperative CTs were available in 51 patients representing 526 imaged screws, which showed a significantly higher rate of severely malpositioned (>4 mm) screws in the fluoroscopic group than the CT navigation group (3.3% vs. 1.0%, p = .027). There was a 3.6% rate of return to OR for pedicle screw malposition in the freehand/fluoroscopic group compared with 0% in the CT-guided navigation group (p = .048). Including patients with less than two-year follow-up (169 fluoroscopy, 220 CT guidance) also found higher rates of screw malposition (13.5% vs. 7.1%, p = .004), severe screw malposition (3.0% vs. 0.50%, p = .04), and return to OR due to screw malposition (2.4% vs. 0%, p = .02) in patients with screws placed using fluoroscopic guidance.

CONCLUSION

Patients with pedicle screws placed with CT-guided navigation had a lower rate of severely malpositioned screws and unplanned returns to the OR. There was no significant difference in blood loss or operative time when controlling for number of levels fused.

SIGNIFICANCE

In the era of health care "never-events," return to OR for screw malposition could certainly be deemed unacceptable. Use of intraoperative CT-guided navigation thus far eliminated return to OR for screw malposition in a complex cohort of pediatric spinal deformity patients, without measurable increase in operative time or blood loss.

Rigid segmental cervical spine instrumentation is safe and efficacious in younger children

PURPOSE

The utilization of cervical spine instrumentation in the young pediatric patient is not well reported. This study presents outcomes and complications of cervical spine instrumentation in patients who underwent cervical spine fusion surgery before age 10.

METHODS

Radiographic and clinical data were collected on all patients who underwent cervical spine surgery with instrumentation at a single institution between January 1, 2006, and March 31, 2015. Patients were ≤ 10 years of age at the time of surgery with any cervical spine deformity/injury diagnosis. Patient demographics, details on cervical spine diagnosis, procedural data, imaging data, and postoperative follow-up data were collected.

RESULTS

Twenty children met the criteria and were included in the study with a mean follow-up of 10.6 months (3 months-2 years). Initial indication for cervical spine correction surgery included deformity (7 cases), trauma (6 cases), instability (3 cases), stenosis (2 cases), rotary subluxation (1 case), and infection (1 case). Fifteen cases were treated with adult 3.5-mm cervical spine instrumentation, 3 with wiring (1 sublaminar and 2 spinous process), and 2 with cannulated screws. Postoperative immobilization included 16 halo fixation, 3 collars, and 1 CTO. Overall, there were five complications related to the surgery. Two patients who had wiring (1 sublaminar and 1 spinous process) developed a non-union and required revision surgery (1 with cannulated screws and 1 with 3.5-mm segmental cervical spine instrumentation). One patient developed a postoperative infection that required incision and drainage. Five patients developed superficial pin infections for their halo. Two deformity patients experienced neurological complications that were likely unrelated to the cervical instrumentation.

CONCLUSIONS

Rigid segmental fixation can be safe and efficacious when used in pediatric cervical spine patients. Whether used with halo or orthosis, patients experience minimal to no complications from the instrumentation and achieve successful fusion. Cervical spine wiring had a high risk of non-union requiring revision surgery. The incidence of wound infection was low with one in 20 cases.

Robotic-assisted navigated minimally invasive pedicle screw placement in the first 100 cases at a single institution

Proper pedicle screw placement is an integral part of spine fusion requiring expertly trained spine surgeons. Advances in medical imaging guidance have improved accuracy. There is high interest in the emerging field of robot-assisted spine surgery; however, safety and accuracy studies are needed. This study describes the pedicle screw placement of the first 100 cases in which navigated robotic assistance was used in a private practice clinical setting. A single-surgeon, single-site retrospective Institutional Review Board-exempt review of the first 100 navigated robot-assisted spine surgery cases was performed. An orthopaedic surgeon evaluated screw placement using plain film radiographs. In addition, pedicle screw malposition, reposition, and return to operating room (OR) rates were collected. Results demonstrated a high level (99%) of successful surgeon assessed pedicle screw placement in minimally invasive navigated robot-assisted spine surgery, with no malpositions requiring return to the OR.