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

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

Percutaneous placement of pedicle screws is a well-established technique, however, no studies have compared percutaneous and open placement of screws in the thoracic spine. The aim of this cadaveric study was to compare the accuracy and safety of these techniques at the thoracic spinal level. A total of 288 screws were inserted in 16 (eight cadavers, 144 screws in percutaneous and eight cadavers, 144 screws in open). Pedicle perforations and fractures were documented subsequent to wide laminectomy followed by skeletalisation of the vertebrae. The perforations were classified as grade 0: no perforation, grade 1: < 2 mm perforation, grade 2: 2 mm to 4 mm perforation and grade 3: > 4 mm perforation. In the percutaneous group, the perforation rate was 11.1% with 15 (10.4%) grade 1 and one (0.7%) grade 2 perforations. In the open group, the perforation rate was 8.3% (12 screws) and all were grade 1. This difference was not significant (p = 0.45). There were 19 (13.2%) pedicle fractures in the percutaneous group and 21 (14.6%) in the open group (p = 0.73). In summary, the safety of percutaneous fluoroscopy-guided pedicle screw placement in the thoracic spine between T4 and T12 is similar to that of the conventional open technique. Cite this article: Bone Joint J 2015;97-B:1555–61

Aims. 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). Patients and Methods. A total of 592 pedicle screws, which were used in 107 consecutively operated patients (210 COMB, 382 POST), were analysed. The accuracy of positioning was determined according to the classification of Gertzbein and Robbins on post-operative CT scans. Results. High accuracy was achieved in 524 screws (88.5%), 192 (87.7%) in the cervical spine and 332 (89%) in the thoracic spine, respectively. The results in the two surgical groups were compared and a logistic regression mixed model was performed to analyse the risk of low accuracy. Significantly lower accuracy was found in the COMB group with 82.9% versus 91.6% in the POST group (p = 0.036). There were no neurological complications, but two vertebral artery lesions were recorded. Three patients underwent revision surgery for malpositioning of a screw. Although the risk of malpositioning of a screw after primary anterior surgery was estimated to be 2.4-times higher than with posterior surgery alone, the overall rates of complication and revision were low. Conclusion. We therefore conclude that CT navigated pedicle screws can be positioned safely although greater caution must be taken in patients who have previously undergone anterior surgery. Cite this article: Bone Joint J 2017;99-B:1373–80

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. Diagnosis of cauda equina syndrome (CES) remains difficult; clinical assessment has low accuracy in reliably predicting MRI compression of the cauda equina (CE). This prospective study tests the usefulness of ultrasound bladder scans as an adjunct for diagnosing CES. Methods. A total of 260 patients with suspected CES were referred to a tertiary spinal unit over a 16-month period. All were assessed by Board-eligible spinal surgeons and had transabdominal ultrasound bladder scans for pre- and post-voiding residual (PVR) volume measurements before lumbosacral MRI. Results. The study confirms the low predictive value of ‘red flag’ symptoms and signs. Of note ‘bilateral sciatica’ had a sensitivity of 32.4%, and a positive predictive value (PPV) of only 17.2%, and negative predictive value (NPV) 88.3%. Use of a PVR volume of ≥ 200 ml was a demonstrably more accurate test for predicting cauda equina compression on subsequent MRI (p < 0.001). The PVR sensitivity was 94.1%, specificity 66.8%, PPV 29.9% and NPV 98.7%. The PVR allowed risk-stratification with 13% patients deemed ‘low-risk’ of CES. They had non-urgent MRI scans. None of the latter scans showed any cauda equina compression (p < 0.006) or individuals developed subsequent CES in the intervening period. There were considerable cost-savings associated with the above strategy. Conclusion. This is the largest reported prospective evaluation of suspected CES. Use of the PVR volume ≥ 200 ml was considerably more accurate in predicting CES. It is a useful adjunct to conventional clinical assessment and allows risk-stratification in managing suspected CES. If adopted widely it is less likely incomplete CES would be missed. Cite this article: Bone Joint J 2020;102-B(6):677–682

Introduction. Halo traction, either on bed or with an accompanying vest is used commonly in Spine surgery, in a variety of clinical situations. The pins are inserted into the skull in safe anatomic zones, using wrenches that are either pre-torqued or exhibit a torque gauge to allow measurable torque application. A torque of 6 – 8 inch pounds is considered ideal for optimal pin tightening. Lesser torques may hypothetically lead to pin loosening and pin track infections, while, excessive torques could lead to pin penetration through the skull. Aim. To test the accuracy and consistency of different torque wrenches used for Halo pin insertion, using a standardised calibration device. Methodology. Three different types of torque wrenches were tested, using the MTS Systems 858 Mini Bionix II calibration device at the School of Engineering laboratory in Cardiff. Each type had four samples. Three more samples of one type, which were already in use at the Spine unit were also tested, making a total sample size of fifteen. The calibration device had a declared average error of 0.5 %. Each torque wrench was tested twenty five times to a pre set value of 6 inch pounds (0.67790897 N-m), resulting in 375 independent observations. Data was recorded electronically and was analysed for error, percentage of error and variability for each device. Results. All wrenches, regardless of model or make, failed to deliver accurate torque at the pre set value on repeated testing. There were both negative and positive errors. The average torque delivered by all wrenches together at a pre set value of 0.67790897 N-m was 0.721337 (+/- 0.116919) N-m. The average percent error for individual wrenches ranged from 4 % to 34 %. When grouped by model, the average percent error (model specific) ranged from 5 % to 29 %. When assessed for consistency, the wrenches revealed a range of values over a minimum of 0.053303 N-m to a maximum of 0.846512 N-m. The variability of all wrenches of one model type was however similar, though not identical. The best performing model had an average variation over 0.165531 N-m while the value for the worst was 0.685794 N-m. Conclusion. Torque wrenches used to tighten Halo pins appear to be neither accurate nor consistent. They deliver torques that are either less than or more than their pre set levels. Different wrenches of one model displayed a similar pattern of variability. While this study does not seek to relate this lack of accuracy and consistency to the development of specific complications like loosening or penetration, it does suggest that extreme care is advisable while using torque wrenches to minimise clinical mishaps

In this study we aim to establish which symptoms and signs are able to reliably predict the presence or absence of cauda equina syndrome.

Prospective collection of data was carried out over 10 months on all patients referred with suspected cauda equina syndrome(CES) to a single spinal unit. 28 patients were referred.

MRI was normal in 4 (14%) patients. 4 (14%) had disc prolapse causing CES and 3 (11%) had spinal metastatic disease. All patients with CES presented with low back pain, unilateral sciatica, urinary dysfunction (painless retention 2, incontinence 2), altered perianal sensation and abnormal anal tone. 1 described constipation. Of patients without CES or malignancy 21 (100%) complained of low back pain, 19 (90%) sciatica (15 unilateral, 4 bilateral), 12 urinary dysfunction (incontinence 5, reduced sensation 3, painless retention 2, urgency 1, terminal dribbling 1) and 5 described altered bowel habit. 7 (33%) exhibited altered perianal sensation and 1 (5%) abnormal anal tone.

The patients with spinal metastases all described back pain but no sciatica. 2 had urinary retention and constipation with 1 having abnormal perianal sensation and anal tone.

This study suggests abnormal anal tone (sensitivity 1.0, specificity 0.95) and altered perianal sensation (sensitivity 1.0, specificity 0.67) are the most reliable predictors of CES. Thorough clinical examination is essential. Back pain with bladder and/or bowel dysfunction without sciatica should raise the suspicion of malignancy.

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. Methods. The authors reviewed the prospectively collected data on 196 adult patients who had pedicle screws implanted with robot-navigated assistance (RNA) using the Mazor X Stealth system between June 2019 and March 2022. Pedicle screws were implanted by one experienced spinal surgeon after completion of a learning period. The accuracy of pedicle screw placement was determined using intraoperative 3D fluoroscopy. Results. A total of 1,123 pedicle screws were implanted: 1,001 screws (89%) were placed robotically, 63 (6%) were converted from robotic placement to a freehand technique, and 59 (5%) were planned to be implanted freehand. Of the robotically placed screws, 942 screws (94%) were determined to be Gertzbein and Robbins grade A with median deviation of 0.8 mm (interquartile range 0.4 to 1.6). Skive events were noted with 20 pedicle screws (1.8%). No adverse clinical sequelae were noted in the 90-day follow-up. The mean fluoroscopic exposure per screw was 4.9 seconds (SD 3.8). Conclusion. RNA is highly accurate and reliable, with a low rate of abandonment once mastered. No adverse clinical sequelae occurred after implanting a large series of pedicle screws using the latest generation of RNA. Understanding of patient-specific anatomical features and the real-time intraoperative identification of risk factors for suboptimal screw placement have the potential to improve accuracy further. Cite this article: Bone Joint J 2023;105-B(5):543–550

Aims. This systematic review aims to identify 3D predictors derived from biplanar reconstruction, and to describe current methods for improving curve prediction in patients with mild adolescent idiopathic scoliosis. Methods. A comprehensive search was conducted by three independent investigators on MEDLINE, PubMed, Web of Science, and Cochrane Library. Search terms included “adolescent idiopathic scoliosis”,“3D”, and “progression”. The inclusion and exclusion criteria were carefully defined to include clinical studies. Risk of bias was assessed with the Quality in Prognostic Studies tool (QUIPS) and Appraisal tool for Cross-Sectional Studies (AXIS), and level of evidence for each predictor was rated with the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach. In all, 915 publications were identified, with 377 articles subjected to full-text screening; overall, 31 articles were included. Results. Torsion index (TI) and apical vertebral rotation (AVR) were identified as accurate predictors of curve progression in early visits. Initial TI > 3.7° and AVR > 5.8° were predictive of curve progression. Thoracic hypokyphosis was inconsistently observed in progressive curves with weak evidence. While sagittal wedging was observed in mild curves, there is insufficient evidence for its correlation with curve progression. In curves with initial Cobb angle < 25°, Cobb angle was a poor predictor for future curve progression. Prediction accuracy was improved by incorporating serial reconstructions in stepwise layers. However, a lack of post-hoc analysis was identified in studies involving geometrical models. Conclusion. For patients with mild curves, TI and AVR were identified as predictors of curve progression, with TI > 3.7° and AVR > 5.8° found to be important thresholds. Cobb angle acts as a poor predictor in mild curves, and more investigations are required to assess thoracic kyphosis and wedging as predictors. Cumulative reconstruction of radiographs improves prediction accuracy. Comprehensive analysis between progressive and non-progressive curves is recommended to extract meaningful thresholds for clinical prognostication. Cite this article: Bone Jt Open 2024;5(3):243–251

Aims. To determine the major risk factors for unplanned reoperations (UROs) following corrective surgery for adult spinal deformity (ASD) and their interactions, using machine learning-based prediction algorithms and game theory. Methods. Patients who underwent surgery for ASD, with a minimum of two-year follow-up, were retrospectively reviewed. In total, 210 patients were included and randomly allocated into training (70% of the sample size) and test (the remaining 30%) sets to develop the machine learning algorithm. Risk factors were included in the analysis, along with clinical characteristics and parameters acquired through diagnostic radiology. Results. Overall, 152 patients without and 58 with a history of surgical revision following surgery for ASD were observed; the mean age was 68.9 years (SD 8.7) and 66.9 years (SD 6.6), respectively. On implementing a random forest model, the classification of URO events resulted in a balanced accuracy of 86.8%. Among machine learning-extracted risk factors, URO, proximal junction failure (PJF), and postoperative distance from the posterosuperior corner of C7 and the vertical axis from the centroid of C2 (SVA) were significant upon Kaplan-Meier survival analysis. Conclusion. The major risk factors for URO following surgery for ASD, i.e. postoperative SVA and PJF, and their interactions were identified using a machine learning algorithm and game theory. Clinical benefits will depend on patient risk profiles. Cite this article: Bone Joint Res 2023;12(4):245–255

Aims. The aims of this study were to determine the diagnostic yield of image-guided biopsy in providing a final diagnosis in patients with suspected infectious spondylodiscitis, to report the diagnostic accuracy of various microbiological tests and histological examinations in these patients, and to report the epidemiology of infectious spondylodiscitis from a country where tuberculosis (TB) is endemic, including the incidence of drug-resistant TB. Methods. A total of 284 patients with clinically and radiologically suspected infectious spondylodiscitis were prospectively recruited into the study. Image-guided biopsy of the vertebral lesion was performed and specimens were sent for various microbiological tests and histological examinations. The final diagnosis was determined using a composite reference standard based on clinical, radiological, serological, microbiological, and histological findings. The overall diagnostic yield of the biopsy, and that for each test, was calculated in light of the final diagnosis. Results. The final diagnosis was tuberculous spondylodiscitis in 250 patients (88%) and pyogenic spondylodiscitis in 22 (7.8%). Six (2.1%) had a noninfectious condition-mimicking infectious spondylodiscitis, and six (2.1%) had no definite diagnosis and improved without specific treatment. The diagnosis was made by image-guided biopsy in 152 patients (56%) with infectious spondylodiscitis. Biopsy was contributory in identifying 132/250 patients (53%) with tuberculous spondylodiscitis, and 20/22 patients (91%) with pyogenic spondylodiscitis. Histological examination was the most sensitive diagnostic modality, followed by Xpert MTB/RIF assay. Conclusion. Image-guided biopsy has a reasonably high diagnostic yield in patients with suspected infectious spondylodiscitis. A combination of histological examination, Xpert MTB/RIF assay, bacterial culture, and sensitivity provides high diagnostic accuracy in a country in which TB is endemic. Cite this article: Bone Joint J 2022;104-B(1):120–126

Aims. To report the development of the technique for minimally invasive lumbar decompression using robotic-assisted navigation. Methods. Robotic planning software was used to map out bone removal for a laminar decompression after registration of CT scan images of one cadaveric specimen. A specialized acorn-shaped bone removal robotic drill was used to complete a robotic lumbar laminectomy. Post-procedure advanced imaging was obtained to compare actual bony decompression to the surgical plan. After confirming accuracy of the technique, a minimally invasive robotic-assisted laminectomy was performed on one 72-year-old female patient with lumbar spinal stenosis. Postoperative advanced imaging was obtained to confirm the decompression. Results. A workflow for robotic-assisted lumbar laminectomy was successfully developed in a human cadaveric specimen, as excellent decompression was confirmed by postoperative CT imaging. Subsequently, the workflow was applied clinically in a patient with severe spinal stenosis. Excellent decompression was achieved intraoperatively and preservation of the dorsal midline structures was confirmed on postoperative MRI. The patient experienced improvement in symptoms postoperatively and was discharged within 24 hours. Conclusion. Minimally invasive robotic-assisted lumbar decompression utilizing a specialized robotic bone removal instrument was shown to be accurate and effective both in vitro and in vivo. The robotic bone removal technique has the potential for less invasive removal of laminar bone for spinal decompression, all the while preserving the spinous process and the posterior ligamentous complex. Spinal robotic surgery has previously been limited to the insertion of screws and, more recently, cages; however, recent innovations have expanded robotic capabilities to decompression of neurological structures. Cite this article: Bone Jt Open 2024;5(9):809–817

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

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

Purposes and Background. Musculoskeletal disorders including as back and neck pain are leading causes of work disability. Effective interventions exist (i.e. functional restoration, multidisciplinary biopsychosocial rehabilitation, workplace-based interventions, etc.), but it is difficult to select the optimal intervention for specific patients. The Work Assessment Triage Tool (WATT) is a clinical decision support tool developed using machine learning to help select interventions. The WATT algorithm categorizes patients based on individual, occupational, and clinical characteristics according to likelihood of successful return-to-work following rehabilitation. Internal validation showed acceptable classification accuracy, but WATT has not been tested beyond the original development sample. Our purpose was to externally validate the WATT. Methods and Results. A population-based cohort design was used, with administrative and clinical data extracted from a Canadian provincial compensation database. Data were available on workers being considered for rehabilitation between January 2013 and December 2016. Data was obtained on patient characteristics (ie. age, sex, education level), clinical factors (ie. diagnosis, part of body affected, pain and disability ratings), occupational factors (ie. occupation, employment status, modified work availability), type of rehabilitation program undertaken, and return-to-work outcomes (receipt of wage replacement benefits 30 days after assessment). Analysis included classification accuracy statistics of WATT recommendations for selecting interventions that lead to successful RTW outcomes. The sample included 5296 workers of which 33% had spinal conditions. Sensitivity of the WATT was 0.35 while specificity was 0.83. Overall accuracy was 73%. Conclusion. Accuracy of the WATT for selecting successful rehabilitation programs was modest. Algorithm revision and further validation is needed. No conflicts of interest. Sources of funding: Funding was provided by the Workers' Compensation Board of Alberta

Aims. The aim of this study was to determine the diagnostic utility of histological analysis in spinal biopsies for spondylodiscitis (SD). Patients and Methods. Clinical features, radiology, results of microbiology, histology, and laboratory investigations in 50 suspected SD patients were evaluated. In 29 patients, the final (i.e. treatment-based) diagnosis was pyogenic SD; in seven patients, the final diagnosis was mycobacterial SD. In pyogenic SD, the neutrophil polymorph (NP) infiltrate was scored semi-quantitatively by determining the mean number of NPs per (×400) high-power field (HPF). Results. Of the 29 pyogenic SD patients, 17 had positive microbiology and 21 positive histology (i.e. one or more NPs per HPF on average). All non-SD patients showed less than one NP per HPF. The presence of one or more NPs per HPF had a diagnostic sensitivity of 72.4%, specificity 100%, accuracy 100%, positive predictive value (PPV) 81.0%, and negative predictive value (NPV) 61.9%. Sensitivity, specificity, and accuracy were greater using the criterion of positive histology and/or microbiology than positive histology or microbiology alone. Granulomas were identified histologically in seven mycobacterial SD patients, and positive microbiology was detected in four. Conclusion. The diagnosis of pyogenic SD was more often confirmed by positive histology (one or more NPs per HPF on average) than by microbiology, although diagnostic sensitivity was greater when both histology and microbiology were positive. Cite this article: Bone Joint J 2019;101-B:246–252

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

Aims. Clinical decision support systems (CDSS) can support clinicians in selecting appropriate treatments for patients. The objective of this study was to examine if triaging patients with LBP to the most optimal treatment can be improved by using a data-driven approach with the help of machine learning as base of such a CDSS. Methods. A clinical database of the Groningen Spine Center containing patient-reported data from 1546 patients with LBP was used. From this dataset, a training dataset with 354 features was labeled on eight different treatments actually received by these patients. With this dataset, models were trained. A test dataset with 50 cases judged on treatments by 4 experts in LBP triage was used to test these models with data not used to train the models. Prediction accuracy and average area under curve (AUC) were used as performance measures for the models. Results. The AUC values indicated small to medium learning effects showing that machine learning on patient-reported data, to model decision-making processes on treatments for LBP, may be possible. One of the best performing models was the Bayesian Network (BN) model; e.g. predicted surgery with accuracy 0.78 (95% C.I. 0.68– 0.87) and AUC 0.70. Conclusion. Benefits to using BNs compared to other supervised machine learning techniques are that it is easy to exploit expert knowledge in BN models, meaning that advices generated by the model can be explained. The next step is to improve the BN accuracy so that it can actually be used in a CDSS. No conflicts of interest. Sources of funding: This work is partly funded by a grant from the Netherlands Organization for Health Research and Development (ZonMw), grant 10-10400-98-009

Introduction and Objective. Almost 60% of the population can expect to experience low back pain (LBP) during their life. Several radiological tools are used to investigate LBP. However, adequate evidence is unavailable to support the use of single photon emission computer tomography (SPECT) in patients with LBP. The objective of this study is to assess the role and efficiency of SPECT in evaluation and management of patients with LBP. Method. Ninety-two patients with LBP were examined and assessed. All the patients received a magnetic resonance imaging (MRI) scan and were referred for a SPECT. We interpreted the modic and degenerative changes found on the MRI and compared it with SPECT tracer uptake. SPECT was used to identify the pain generator and then a surgical plan was made. Data was analyzed for pain improvement in those who underwent surgical treatment to establish the accuracy of CT SPECT in identification of primary pain generator. Results. A total of 184 patients were included in the study who underwent diagnostic CT-SPECT between January 2013 and December 2019. One hundred of them were females and Eighty four males; the mean age was 47.6 years. 111 patients underwent surgery in the form of interbody fusion or posterolateral fusion. 16 patients positive tracer uptake was at asymptomatic level or unrelated. In 3 patients SPECT identified screw sites as pain generator and in all 3 patients screws were removed with good pain relief. Overall axial pain as measured with Numeric rating scale was preoperatively 9.13 ± 0.7 and improved to 4.54 ± 2.3 at 6 months postoperative follow up. MRI changes have been analyzed and correlation studied with relation to SPECT findings. Conclusion. Due to its high precision and sensitivity compared to other radiological modalities, SPECT demonstrated the ability to aid in clinical diagnosis. CT SPECT reveals information that becomes vital in deciding further management. In this study, we exemplified that SPECT scan can give indication for pain generator in axial spine pain and aid in surgical intervention