Aims. Intraoperative 3D navigation (ION) allows high accuracy to be achieved in spinal surgery, but poor workflow has prevented its widespread uptake. The technical demands on ION when used in patients with adolescent idiopathic scoliosis (AIS) are higher than for other more established indications. Lean principles have been applied to industry and to health care with good effects. While ensuring optimal accuracy of instrumentation and safety, the implementation of ION and its associated productivity was evaluated in this study for AIS surgery in order to enhance the workflow of this technique. The aim was to optimize the use of ION by the application of lean principles in AIS surgery. Methods. A total of 20 consecutive patients with AIS were treated with ION corrective spinal surgery. Both qualitative and quantitative analysis was performed with real-time modifications. Operating time, scan time, dose length product (measure of CT radiation exposure), use of fluoroscopy, the influence of the reference frame, blood loss, and neuromonitoring were assessed. Results. The greatest gains in productivity were in avoiding repeat intraoperative scans (a mean of 248 minutes for patients who had two scans, and a mean 180 minutes for those who had a single scan). Optimizing accuracy was the biggest factor influencing this, which was reliant on incremental changes to the operating setup and technique. Conclusion. The application of lean principles to the introduction of ION for AIS surgery helps assimilate this method into the environment of the operating theatre. Data and stakeholder analysis identified a reproducible technique for using ION for AIS surgery, reducing operating time, and radiation exposure. Cite this article: Bone Joint J. 2020;102-B(1):5–10

With the identification of literature shortfalls on the techniques employed in intraoperative navigated (ION) spinal surgery, we outline a number of measures which have been synthesised into a coherent operative technique. These include positioning, dissection, management of the reference frame, the grip, the angle of attack, the drill, the template, the pedicle screw, the wire, and navigated intrathecal analgesia. Optimizing techniques to improve accuracy allow an overall reduction of the repetition of the surgical steps with its associated productivity benefits including time, cost, radiation, and safety.

Cite this article: Bone Joint J 2020;102-B(3):371–375.

To assess screw malposition rates and complications associated with pedicle screw insertion using 3D navigation technology. A retrospective study was undertaken for all cases where O-arm® and StealthStation® systems were used over a 2-year period. The primary outcome measure was return to theatre rates for pedicle screw malposition. A total of 938 screws were inserted (934 thoracolumbar and 4 cervical), and 103 patients underwent spinal fixation using O-arm® and StealthStation® navigation. 64 were revision cases and 39 primary cases. Average number of levels was 4.6. There were a total of 10 complications: 3 infections, 1 DVT, 1 PE, 1 fast atrial fibrillation (AF), 1 screw malposition, 1 non-union, 1 undisplaced vertebral body fracture and 1 nerve root compression following osteotomy. The percentage return to theatre for screw malposition using 3D navigation was 1% of patients and 0.1% of pedicle screws. No patients developed permanent neurological compromise. These systems provide accuracy that is comparable to traditional 2D fluoroscopic techniques. We advocate their use in the safe insertion of pedicle screws in complex revision deformity cases where original anatomical landmarks are absent or obscured. We also believe that radiation exposure is considerably less with navigation especially in these complex and revision cases

Introduction. Tomita En-bloc spondylectomy (TES) of L5 is one of the most challenging spinal surgical techniques. A 42-year-old female was referred with low back pain and L5 radiculopathy with background of right shoulder excision of liposarcoma. CT-PET confirmed a solitary L5 oligometastasis. MRI showed thecal sac indentation and therefore was not suitable for stereotactic ablative radiotherapy (SABR) alone. Planning Methodology. First Stage: Carbon fibre pedicle screws were planned from L2 to S2AI-Pelvis, aligned to her patient-specific rods. Custom 3D-printed navigation guides were used to overcome challenging limitations of carbon instruments. Radiofrequency ablation (RFA) of L5 pedicles prior to osteotomy was performed to prevent sarcoma cell seeding. Microscope-assisted thecal sac-tumour separation and L5 nerve root dissection was performed. Novel surgical navigation of the ultrasonic bone cutter assisted inferior L4 and superior S1 endplate osteotomies. Second stage: We performed a vascular-assisted retroperitoneal approach to L4-S1 with protection of the great vessels. Completion of osteotomies at L4 and S1 to en-bloc L5: (L4 inferior endplate, L4/5 disc, L5 body, L5/S1 disc and S1 superior endplate). Anterior reconstruction used an expandable PEEK cage obviating the need for a third posterior stage. Reinforced with a patient-specific carbon plate L4-S1 promontory. Sacrifice of left L5 nerve root undertaken. Results. Patient rehabilitated well and was discharged after 42 days. Patient underwent SABR two months post-operatively. Despite left foot drop, she was walking independently 9 months post-operatively. Conclusion. These challenging cases require a truly multi-disciplinary team approach. We share this technique for a dual stage TES and metal-free construct with post adjuvant SABR for maximum local control

Introduction. The placement of a large interbody implant allows for a larger surface area for fusion, vis a vis, via retroperitoneal direct anterior, antero-lateral and lateral approaches. At the same time, spinal navigation facilitates a minimally invasive fixation for inserting posterior pedicle screws. We report on the first procedures in the United Kingdom performed by a single-surgeon at a single- centre using navigated robot-assisted spine surgery without the need for guide-wires. Materials and Methods. Whilst positioned in the supine or lateral position, a routine supine anterior lumbar interbody fusion (ALIF), and/or antero-lateral ALIF (AL-ALIF) and/or lateral lateral interbody fusion (LLIF) is performed. The patient is then turned prone or kept in the single lateral position (SPL) for insertion of the posterior screws performed under robotic guidance. Intraoperative CT scan 3D images captured then are sent to the Robotic software platform for planning of the screw trajectories and finally use again at the end of the procedure to confirm screw accuracy. We identified 34 consecutive patients from October 2019 to January 2020 who underwent robotic assisted spine surgery. The demographic, intraoperative, and perioperative data of all these patients were reviewed and presented. Results. Of the 34 patients, 65 levels were treated in total using 204 screws. Of the 21 patients (60%) who underwent single-level fixation, 14 of them (67%) were treated at the L5/S1 level, 3 at L3/L4, 3 at L4/L5 and 1 at L2/L3 level. The remaining 13 patients (40%) underwent multi-level fixation, of which 4 were adult scoliosis. 15 underwent a supine ALIF approach, 1 underwent AL-ALIF, 8 patients underwent combined LLIF and AL-ALIF approach in a lateral decubitus, whilst 9 underwent pure LLIF approach (of which 3 patients were in the single position lateral) and one patient had previous TLIF surgery. The average estimated blood loss was 60 cc. The average planning time was 10 min and the average duration of surgery was 50 min. The average patient age was 54 years and 64% (22/34) were male. The average BMI was 28.1 kg/m. 2. There were no re-interventions due to complications or mal positioned screws. Conclusion. Minimally invasive spine surgery using robot-assisted navigation yields an improved level of accuracy, decreased radiation exposure, minimal muscle disruption, decreased blood loss, shorter operating theatre time, length of stay, and lower complication rates. Further follow-up of the patients treated will help compare the clinical outcomes with other techniques

Aims. The aim of this study was to systematically compare the safety and accuracy of robot-assisted (RA) technique with conventional freehand with/without fluoroscopy-assisted (CT) pedicle screw insertion for spine disease. Methods. A systematic search was performed on PubMed, EMBASE, the Cochrane Library, MEDLINE, China National Knowledge Infrastructure (CNKI), and WANFANG for randomized controlled trials (RCTs) that investigated the safety and accuracy of RA compared with conventional freehand with/without fluoroscopy-assisted pedicle screw insertion for spine disease from 2012 to 2019. This meta-analysis used Mantel-Haenszel or inverse variance method with mixed-effects model for heterogeneity, calculating the odds ratio (OR), mean difference (MD), standardized mean difference (SMD), and 95% confidence intervals (CIs). The results of heterogeneity, subgroup analysis, and risk of bias were analyzed. Results. Ten RCTs with 713 patients and 3,331 pedicle screws were included. Compared with CT, the accuracy rate of RA was superior in Grade A with statistical significance and Grade A + B without statistical significance. Compared with CT, the operating time of RA was longer. The difference between RA and CT was statistically significant in radiation dose. Proximal facet joint violation occurred less in RA than in CT. The postoperative Oswestry Disability Index (ODI) of RA was smaller than that of CT, and there were some interesting outcomes in our subgroup analysis. Conclusion. RA technique could be viewed as an accurate and safe pedicle screw implantation method compared to CT. A robotic system equipped with optical intraoperative navigation is superior to CT in accuracy. RA pedicle screw insertion can improve accuracy and maintain stability for some challenging areas. Cite this article: Bone Joint Res 2020;9(10):653–666

Aims

The aim of this study was to assess the accuracy of pedicle screw placement, as well as intraoperative factors, radiation exposure, and complication rates in adult patients with degenerative disorders of the thoracic and lumbar spines who have undergone robotic-navigated spinal surgery using a contemporary system.

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The aim of this study was to reassess the rate of neurological, psoas-related, and abdominal complications associated with L4-L5 lateral lumbar interbody fusion (LLIF) undertaken using a standardized preoperative assessment and surgical technique.

Aims

To benchmark the radiation dose to patients during the course of treatment for a spinal deformity.

Study design. Prospective clinical and radiological analysis of children with complex cervical deformities for the safety of cervical pedicle screw insertion. Objectives. To analyse the possibility, safety and efficacy of cervical pedicle screw insertion in complex pediatric cervical deformities, where conventional stabilisation techniques would not have provided rigid fixation. Summary of Background Data. Although the usage of cervical pedicle screws (CPS) in adults has become established, the feasibility and safety of its application in children has not been described previously in the literature. Methods. Sixteen children of mean age 9.7 ± 2.6 years (range: 3 - 13) requiring spinal stabilization for cranio-vertebral junction anomalies (n=10), cervico-thoracic kyphosis/ kyphoscoliosis (n=5) and cervical tumor excision (n=1) formed the study group. Feasibility of CPS insertion was assessed by computerised tomography images. Standard 3.0 mm titanium pedicle screws were inserted using intraoperative Iso-C C arm based 3 D computer navigation and the containment was post operatively evaluated with CT scan. Results. Based on preoperative CT imaging, 55 pedicles were selected for screw fixation. Intra operatively CPS was successfully inserted at 51 levels and at four sclerosed pedicles (7.3%), screws could not be inserted. At 42 levels, the screws were inserted in the classical description of pedicle screw application and in nine deformed vertebra, the screws were inserted in a non-classical fashion, taking purchase in the three columns of the cervical vertebra. Forty five (88.3%) screws were fully contained, six (11.7 %) had a non-critical breach and none had a critical breach. No perioperative complications related to pedicle screw insertion were noted. Conclusion. Safe insertion of cervical pedicle screws is possible in children. Iso-C navigation provides real time virtual imaging and improves the safety and accuracy of successful pedicle fixation even in altered vertebral anatomy. Pedicle width morphometrics do not restrict screw insertion

Study design. Literature review of the best available evidence on the accuracy of computer assisted pedicle screw insertion. Background. Pedicle screw misplacement rates with the conventional insertion technique and adequate postoperative CT examination have ranged from 5 to 29 % in the cervical spine, from 3 to 58 % in the thoracic spine, and from 6 to 41% in the lumbosacral region. Despite these relatively high perforation rates, the incidence of reported screw-related complications has remained low. Interestingly, the highest rates of neurovascular injuries have been reported from the lumbosacral spine in up to 17% of the patients. Gertzbein and Robbins introduced a 4-mm “safe zone” in the thoracolumbar spine for medial encroachment, consisting of 2-mm of epidural and 2-mm of subarachnoid space. Later, several authors have found the safety margins to be significantly smaller, suggesting that the “safe zone” thresholds of Gertzbein and Robbins do not apply to the thoracic spine, and seem to be too high even for the lumbar spine. The midthoracic and midcervical spine, as well as the thoracolumbar junction set the highest demands for accuracy in pedicle screw insertion, with no room for either translational or rotational error at e.g. T5 level. Computer assisted pedicle screw insertion (navigation) was introduced in the early 90's to increase the accuracy and safety of pedicle screw insertion. Material. PubMed literature search revealed two randomized controlled trials (RCT) comparing the in vivo accuracy of conventional and computer assisted pedicle screw insertion techniques. Three meta-analyses have assessed the published reports on the accuracy of pedicle screw insertion with or without computer assistance, one additional meta-analysis concentrated on the functional outcome of computer assisted pedicle screw insertion. Results. The RCTs by Laine et al and Rajasekaran et al achieved significantly higher screw placement accuracy with computer assistance than with the conventional techniquebased on anatomical landmarks. In a degenerative patient population, Laine et al reported a misplacement rate of 4.6% with computer assistance compared to 13.4% with the conventional technique. In addition to this quantitative difference, a qualitative difference in the misplaced screws was noticed: in the conventional group, 28 out of 37 misplaced screws were either inferior or medial, whereas in the computer assisted group, 1 out of 10 misplaced screws was situated in these ”danger zones”. In deformity surgery, Rajasekaran et al reported a 2% pedicle screw misplacement rate with a computer assisted technique compared to 23% with the conventional technique. Interestingly, in their study, the average screw insertion time in the computer assisted group was significantly shorter than with the conventional technique. The three meta-analyses, assessing up to 37 337 pedicle screws, reported significantly higher accuracy in the placement of pedicle screws with computerassistance compared with the conventional methods. The superiority of the computer assisted technique was even more obvious with abnormal surgical anatomy. CT-based and 3D-fluoroscopy-based navigation methods provided better accuracy compared to 2Dfluoroscopy-based navigation. No statistically significant benefit with computer assistance in the incidence of neuro-vascular complications, or in functional outcome was demonstrated. Conclusion. High pedicle screw misplacement rates have been reported with the conventional technique based on anatomical landmarks and intraoperative fluoroscopy. The concept of ”safe zone” is hypothetical, and underestimates the true risks of misplaced pedicle screws. Computer assistance significantly improves the accuracy and safety of pedicle screw insertion. It will, however, be difficult to correlate this increased accuracy to improved patient outcomes

Aims

The direct posterior approach with subperiosteal dissection of the paraspinal muscles from the vertebrae is considered to be the standard approach for the surgical treatment of adolescent idiopathic scoliosis (AIS). We investigated whether or not a minimally-invasive surgery (MIS) technique could offer improved results.

Purpose. Posterior lumbar fusion using minimally invasive surgical (MIS) techniques are reported to minimise postoperative pain, soft tissue damage and length of hospital stay when compared to the traditional open procedure. Methods. This is a review of patients who underwent MIS for posterolateral lumbar fusion in a single practice over a 2-year period. Results. Twenty-eight patients underwent this procedure. The median age was 57 (range 34-80). Male:female ratio was 1:1. The most common symptom was radicular pain (n=26). Two patients had back pain without radicular symptoms. Primary degenerative spondylolisthesis was seen in 22 patients and post-laminectomy spondylolisthesis in 3 patients. Transforaminal interbody fusion (TLIF) with pedicle screw fixation was the commonest procedure (20) while the rest had pedicle screw fixation and inter-transverse fusion. Along with fusion, nerve root decompression alone was performed in 19, while 5 had decompression of the central spinal canal. Intra-operative navigation was used to assist screw placement in 5 patients. The typical hospital stay was 3 days. All but two patients were mobilised the same or the following day. Twenty-one patients with radiculopathy (80%) reported improvement in VAS at 6-months. One patient suffered irreversible nerve root injury (L5). Significant pedicle breach without nerve injury by a screw was seen in one patient. Conclusion. Minimally invasive TLIF and pedicle screw fixation lumbar degenerative condition is a safe procedure with complications comparable to traditional open techniques. Minimal muscle dissection and soft tissue damage allows for earlier ambulation and reduced hospital stay. The procedure however required longer operative time and increased exposure to intra-operative x-rays

Study design. Retrospective study. Objectives. To optimise the radiation doses and image quality for the cone-beam O-arm surgical imaging system in spinal surgery. Summary of Background. Neurovascular compromise has been reported following screw misplacement during thoracic pedicle screw insertion. The use of O-arm with or without navigation system during spinal surgery has been shown to lower the rate of screw misplacement. The main drawback of such imaging surgical systems is the high radiation exposure. Methods. Chest phantom and cadaveric pig spine were examined on the O-arm with different scan settings: two were recommended by the O-arm manufacturer (120 kV/320 mAs, and 120 kV/128 mAs), and three low-dose settings (80 kV/80 mAs, 80 kV/40 mAs, and 60 kV/40 mAs). The radiation doses were estimated by Monte Carlo calculations. Objective evaluation of image quality included interobserver agreement in the measurement of pedicular width in chest phantom and assessment of screw placement in cadaveric pig spine. Results. The effective dose/cm for 120 kV/320 mAs-scan was 13, 26, and 69 times higher than those delivered with 80 kV/80 mAs, 80 kV/40 mAs, and 60 kV/40 mAs-scans, respectively. Images with 60 kV/40 mAs were unreliable. Images with 80 kV/80 mAs were considered reliable with good interobserver agreement when measuring the pedicular width (random error 0.38 mm and intraclass correlation coefficient 0.979) and almost perfect agreement when evaluating the screw placement (κ-value 0.86). Conclusions. The radiation doses of the O-arm system can be reduced 5–13 times without negative impact on image quality with regard to information required for spinal surgery

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We aimed to retrospectively assess the accuracy and safety of CT navigated pedicle screws and to compare accuracy in the cervical and thoracic spine (C2-T8) with (COMB) and without (POST) prior anterior surgery (anterior cervical discectomy or corpectomy and fusion with ventral plating: ACDF/ACCF).

Aims

The aim of this study was to report a retrospective, consecutive series of patients with adolescent idiopathic scoliosis (AIS) who were treated with posterior minimally invasive surgery (MIS) with a mean follow-up of two years (sd 1.4; 0.9 to 0 3.7). Our objectives were to measure the correction of the deformity and record the peri-operative morbidity. Special attention was paid to the operating time (ORT), estimated blood loss (EBL), length of stay (LOS) and further complications.

We undertook a retrospective study investigating the accuracy and safety of percutaneous pedicle screws placed under fluoroscopic guidance in the lumbosacral junction and lumbar spine. The CT scans of patients were chosen from two centres: European patients from University Medical Center Hamburg-Eppendorf, Germany, and Asian patients from the University of Malaya, Malaysia. Screw perforations were classified into grades 0, 1, 2 and 3. A total of 880 percutaneous pedicle screws from 203 patients were analysed: 614 screws from 144 European patients and 266 screws from 59 Asian patients. The mean age of the patients was 58.8 years (16 to 91) and there were 103 men and 100 women. The total rate of perforation was 9.9% (87 screws) with 7.4% grade 1, 2.0% grade 2 and 0.5% grade 3 perforations. The rate of perforation in Europeans was 10.4% and in Asians was 8.6%, with no significant difference between the two (p = 0.42). The rate of perforation was the highest in S1 (19.4%) followed by L5 (14.9%). The accuracy and safety of percutaneous pedicle screw placement are comparable to those cited in the literature for the open method of pedicle screw placement. Greater caution must be taken during the insertion of L5 and S1 percutaneous pedicle screws owing to their more angulated pedicles, the anatomical variations in their vertebral bodies and the morphology of the spinal canal at this location.

Cite this article: Bone Joint J 2015; 97-B:1111–17.

The purpose of this study was to determine whether it would be feasible to use oblique lumbar interbody fixation for patients with degenerative lumbar disease who required a fusion but did not have a spondylolisthesis.

A series of CT digital images from 60 patients with abdominal disease were reconstructed in three dimensions (3D) using Mimics v10.01: a digital cylinder was superimposed on the reconstructed image to simulate the position of an interbody screw. The optimal entry point of the screw and measurements of its trajectory were recorded. Next, 26 cadaveric specimens were subjected to oblique lumbar interbody fixation on the basis of the measurements derived from the imaging studies. These were then compared with measurements derived directly from the cadaveric vertebrae.

Our study suggested that it is easy to insert the screws for L1/2, L2/3 and L3/4 fixation: there was no significant difference in measurements between those of the 3-D digital images and the cadaveric specimens. For L4/5 fixation, part of L5 inferior articular process had to be removed to achieve the optimal trajectory of the screw. For L5/S1 fixation, the screw heads were blocked by iliac bone: consequently, the interior oblique angle of the cadaveric specimens was less than that seen in the 3D digital images.

We suggest that CT scans should be carried out pre-operatively if this procedure is to be adopted in clinical practice. This will assist in determining the feasibility of the procedure and will provide accurate information to assist introduction of the screws.

Cite this article: Bone Joint J 2013;95-B:977–82.

We reviewed 212 consecutive patients with adolescent idiopathic scoliosis who underwent posterior spinal arthrodesis using all pedicle screw instrumentation in terms of clinical, radiological and Scoliosis Research Society (SRS)-22 outcomes. In Group 1 (51 patients), the correction was performed over two rods using bilateral segmental pedicle screws. In Group 2 (161 patients), the correction was performed over one rod using unilateral segmental pedicle screws with the second ^{rod providing stability of the construct through two-level screw fixation at proximal and distal ends. The mean age at surgery was 14.8 years in both groups. Comparison between groups showed no significant differences with regard to age and Risser grade at surgery, pre- and post-operative scoliosis angle, coronal Cobb correction, length of hospital stay and SRS scores. Correction of upper thoracic curves was significantly better in Group 1 (p = 0.02). Increased surgical time and intra-operative blood loss was recorded in Group 1 (p < 0.001 and p = 0.04, respectively). The implant cost was reduced by mean 35% in Group 2 due to the lesser number of pedicle screws.}

Unilateral and bilateral pedicle screw techniques have both achieved excellent deformity correction in adolescent patients with idiopathic scoliosis, which was maintained at two-year follow-up. This has been associated with high patient satisfaction and low complication rates.