AO Spine Guideline for Using Osteobiologics in Spine Degeneration project is an international collaborative initiative to identify and evaluate evidence on existing use of osteobiologics in spine degenerative diseases. It aims to formulate clinically relevant and internationally applicable guidelines ensuring evidence-based, safe and effective use of osteobiologics. The current focus is the use of osteobiologics in anterior cervical discectomy and fusion surgeries. The guideline development is planned in three phases. Phase 1- Evidence synthesis and Recommendation; Phase 2- Guideline with osteobiologics grading and Validation; Phase 3- Guideline dissemination and Development of a clinical decision support tool. The key questions formulating the guidelines for the use of osteobiologics will be addressed in a series of systematic reviews in Phase 1. The evidence synthesized by the systematic reviews will be assessed by Grading of Recommendations, Assessment, Development and Evaluations (GRADE) methodology, including expert panel discussions to formulate a recommendation. In Phase 2, osteobiologics will be graded based on evidence and the grading will be integrated with the recommendation from Phase 1, and thus formulate a guideline. The guideline will be further validated by prospective clinical studies. In the third phase, dissemination of the proposed guideline and development of a decision support tool is planned. AO-GO aims to bridge an important gap between quality of evidence and use of osteobiologics in spine fusion surgeries. With a holistic approach the guideline aims to facilitate evidence-based, patient-oriented decision-making process in clinical practice, thus stimulating further evidence-based studies regarding osteobiologics usage in spine surgeries

A retrospective review of patients with spinal growing rods in a single institution. Demographic data including age at first surgery, diagnosis, pre- and post-operative cobb angles from erect standardised radiographs were collected. The type of construct used i.e. spine to rib or spine to spine was noted along with the type of growing mechanism used (magnetic or cassette). Any complications were collated for each technique. Our results include 26 patients who had growing rod insertion, 12 in the spine - spine group and 14 in rib - spine group. Pre-operative cobb angles of 71 and 78 degrees respectively with a correction to 36 and 35 degrees. Mean age at surgery was 63 months in spine to spine group and 67 months in rib to spine group. Spine to spine group had 2 proximal pull out of hooks and the rib spine group had one pull out of hook. The correction achieved by the new technique is comparable to the spine – spine constructs. Complications are seen in both groups. The perceived benefit of the new technique is the proximal spine is not violated so there is a reduced risk of mass fusion. The canal and pedicles are not included proximally, so there will be no effect on the growing diameter of the canal. Biomechanically the construct is more robust and should allow greater control of the curve. Further follow up and analysis of this new technique is warranted

Prolonged length of stay (LOS) is a significant contributor to the variation in surgical health care costs and resource utilization after elective spine surgery. The primary goal of this study was to identify patient, surgical and institutional variables that influence LOS. The secondary objective is to examine variability in institutional practices among participating centers. This is a retrospective study of a prospectively multicentric followed cohort of patients enrolled in the CSORN between January 2015 and October 2020. A logistic regression model and bootstrapping method was used. A survey was sent to participating centers to assessed institutional level interventions in place to decrease LOS. Centers with LOS shorter than the median were compared to centers with LOS longer than the median. A total of 3734 patients were included (979 discectomies, 1102 laminectomies, 1653 fusions). The median LOS for discectomy, laminectomy and fusion were respectively 0.0 day (IQR 1.0), 1.0 day (IQR 2.0) and 4.0 days (IQR 2.0). Laminectomy group had the largest variability (SD=4.4, Range 0-133 days). For discectomy, predictors of LOS longer than 0 days were having less leg pain, higher ODI, symptoms duration over 2 years, open procedure, and AE (p< 0.05). Predictors of longer LOS than median of 1 day for laminectomy were increasing age, living alone, higher ODI, open procedures, longer operative time, and AEs (p< 0.05). For posterior instrumented fusion, predictors of longer LOS than median of 4 days were older age, living alone, more comorbidities, less back pain, higher ODI, using narcotics, longer operative time, open procedures, and AEs (p< 0.05). Ten centers (53%) had either ERAS or a standardized protocol aimed at reducing LOS. In this study stratifying individual patient and institutional level factors across Canada, several independent predictors were identified to enhance the understanding of LOS variability in common elective lumbar spine surgery. The current study provides an updated detailed analysis of the ongoing Canadian efforts in the implementation of multimodal ERAS care pathways. Future studies should explore multivariate analysis in institutional factors and the influence of preoperative patient education on LOS

Infections in spine surgery are relatively common and devastating complications, a significant burden to the patient and the healthcare system. Usually, the treatment of SSIs consists of aggressive and prolonged antibiotic therapy, multiple debridements, and in chronic cases, hardware removal. Infections are correlated with worse subjective outcomes and even higher mortality. Depending on the type of spine surgery, the infection rate has been reported to be as higher as 20%. Recently silver-coated implants have been introduced in spine surgery to reduce the incidence of post-operative infections and to improve implant survivorship. The aim of the present study is to evaluate complications and outcomes in patients treated with silver-coated implants because of spine infection. All consecutive patients who had spine stabilization with a silver-coated implant from 2018 to 2021 were screened for inclusion in the study. Inclusion criteria were: (1) six months of minimum follow-up; (2) previous surgical site infection; hematogenous spondylodiscitis requiring surgical stabilization. Demographic and surgical information were obtained via chart review, all the device-related complications and the reoperation rate were also reported. A total of 57 patients were included in the present study. The mean age was 63.4 years, and there were 36 (63%) males and 21 (37%) females. Among the included cases, 57% were SSIs, 33% were spondylodiscitis, and 9% were hardware mobilization. Comorbidities such as diabetes mellitus, obesity, smoke, and oncological history were significant risk factors. In addition, the organisms cultured were Staphylococcus species in most of the cases. At six months of follow-up, 40% of patients were considered free from infection, while 20% needed multiple surgeries. The present research showed satisfactory results of silver-coated implants for the treatment of spine infection

Background. Lateral lumbar spine statistical shape models (SSM) have been used previously to describe associations with osteoarthritis and back pain. However, associations with factors such as osteoporosis, menopause and parity have not been explored. Methods and Results. A 143-point SSM, describing L1 to the top of L5, was applied to lateral spine iDXA scans from UK Biobank. Associations with self-reported osteoporosis, menopause, parity and back pain and the first 10 modes of variation were examined using adjusted binary logistic regression or linear regression (adjusted for age, height, weight and total spine BMD). We report odds ratios with 95% confidence intervals for each standard deviation change in mode. Complete data were available for 2494 women. Mean age was 61.5 (± 7.4) years. 1369 women reported going through menopause, 96 women self-reported osteoporosis and 339 women reported chronic back pain. 80% of women reported at least 1 live birth. Lumbar spine shape was not associated with back pain in this cohort. Two modes were associated with menopause (modes 1 & 2), 1 mode with parity (mode 1) and 2 modes with osteoporosis (modes 3 & 5). Mode 1 (43.6% total variation), describing lumbar curvature was positively associated with both menopause [OR 1.15 95% CI 1.00–1.33, p=0.05] and parity [OR 1.058 95% CI 1.03–1.0, p=0.01]. Mode 3, describing decreased vertebral height was positively associated with osteoporosis [OR 1.40 95% CI 1.14–1.73, p=0.001]. Conclusion. Menopause and parity were associated with a curvier lumbar spine and osteoporosis with decreased vertebral height. Shape was not associated with back pain. No conflicts of interest.  . Sources of funding. Wellcome Trust collaborative award ref 209233

Adult Spine Deformity (ASD) is a degenerative condition of the adult spine leading to altered spine curvatures and mechanical balance. Computational approaches, like Finite Element (FE) Models have been proposed to explore the etiology or the treatment of ASD, through biomechanical simulations. However, while the personalization of the models is a cornerstone, personalized FE models are cumbersome to generate. To cover this need, we share a virtual cohort of 16807 thoracolumbar spine FE models with different spine morphologies, presented in an online user-interface platform (SpineView). To generate these models, EOS images are used, and 3D surface spine models are reconstructed. Then, a Statistical Shape Model (SSM), is built, to further adapt a FE structured mesh template for both the bone and the soft tissues of the spine, through mesh morphing. Eventually, the SSM deformation fields allow the personalization of the mean structured FE model, leading to generate FE meshes of thoracolumbar spines with different morphologies. Models can be selectively viewed and downloaded through SpineView, according to personalized user requests of specific morphologies characterized by the geometrical parameters: Pelvic Incidence; Pelvic Tilt; Sacral Slope; Lumbar Lordosis; Global Tilt; Cobb Angle; and GAP score. Data quality is assessed using visual aids, correlation analyses, heatmaps, network graphs, Anova and t-tests, and kernel density plots to compare spinopelvic parameter distributions and identify similarities and differences. Mesh quality and ranges of motion have been assessed to evaluate the quality of the FE models. This functional repository is unique to generate virtual patient cohorts in ASD. Acknowledgements: European Commission (MSCA-TN-ETN-2020-Disc4All-955735, ERC-2021-CoG-O-Health-101044828)

A stiff spine leads to increased demand on the hip, creating an increased risk of total hip arthroplasty (THA) dislocation. Several authors propose that a change in sacral slope of ≤10° between the standing and relaxed-seated positions (ΔSSstanding→relaxed-seated) identifies a patient with a stiff lumbar spine and have suggested use of dual-mobility bearings for such patients. However, such assessment may not adequately test the lumbar spine to draw such conclusions. The aim of this study was to assess how accurately ΔSSstanding→relaxed-seated can identify patients with a stiff spine. This is a prospective, multi-centre, consecutive cohort series. Two-hundred and twenty-four patients, pre-THA, had standing, relaxed-seated and flexed-seated lateral radiographs. Sacral slope and lumbar lordosis were measured on each functional X-ray. ΔSSstanding→relaxed-seated seated was determined by the change in sacral slope between the standing and relaxed-seated positions. Lumbar flexion (LF) was defined as the difference in lumbar lordotic angle between standing and flexed-seated. LF≤20° was considered a stiff spine. The predictive value of ΔSSstanding→relaxed-seated for characterising a stiff spine was assessed. A weak correlation between ΔSSstanding→relaxed-seated and LF was identified (r2= 0.15). Fifty-four patients (24%) had ΔSSstanding→relaxed-seated ≤10° and 16 patients (7%) had a stiff spine. Of the 54 patients with ΔSSstanding→relaxed-seated ≤10°, 9 had a stiff spine. The positive predictive value of ΔSSstanding→relaxed-seated ≤10° for identifying a stiff spine was 17%. ΔSSstanding→relaxed-seated ≤10° was not correlated with a stiff spine in this cohort. Utilising this simplified approach could lead to a six-fold overprediction of patients with a stiff lumbar spine. This, in turn, could lead to an overprediction of patients with abnormal spinopelvic mobility, unnecessary use of dual mobility bearings and incorrect targets for component alignment. Referring to patients ΔSSstanding→relaxed-seated ≤10° as being stiff can be misleading; we thus recommend use of the flexed-seated position to effectively assess pre-operative spinopelvic mobility

Purpose. Patients may present with concurrent symptomatic hip and spine problems, with surgical treatment indicated for both. Controversy exists over which procedure, total hip arthroplasty (THA) or lumbar spine procedure, should be performed first, and does the surgeon's area of expertise influence the choice. Materials & Methods. Clinical scenarios were devised for 5 fictional patients with both symptomatic hip and lumbar spine disorders for which surgical treatment was indicated. An email with survey link was sent to 110 clinical members of the Hip Society and 101 experienced spine surgeons in the USA requesting responses to: which procedure should be performed first, and the rationale for the decision with comments. The clinical scenarios were painful hip osteoarthritis and (1) lumbar spinal stenosis with neurologic claudication; (2) lumbar degenerative spondylolisthesis with leg pain; (3) lumbar disc herniation with leg weakness; (4) lumbar scoliosis with back pain; and (5) thoracolumbar disc herniation with myelopathy. Surgeon choices were compared among scenarios and between surgical specialties using chi-square analysis and comments analyzed using text mining. Results. Complete responses were received from 51 hip surgeons (46%), with a mean of 30.8 (+ 10.4) years of practice experience, and 37 spine surgeons (37%), with a mean of 23.4 (+ 6.5) years of experience. The percentages of hip surgeons recommending “THA first” differ significantly among scenarios: 59% for scenario 1; 73% for scenario 2; 47% for scenario 3; 47% for scenario 4; and 10% for scenario 5 (χ. 2. =44.5, p<0.001). The percentages of spine surgeons recommending “THA first” were 49% for scenario 1; 70% for scenario 2; 19% for scenario 3; 78% for scenario 4; and 0% for scenario 5. There were significant differences between the surgeon groups only for scenarios 3 and 4 (Fishers exact test, p=0.003 and p=0.006 respectively). Hip surgeons were significantly more likely to choose “THA first” despite radicular leg pain (scenario 2), and less likely to choose “THA first” with the presence of myelopathy (scenario 5). The choice of “THA first” in scenarios 1, 3, and 4 were more equivocal, dependent on surgeon impression of clinical severity. Spine surgeons were more likely to recommend THA first with back pain caused by spinal deformity, and spine surgery first with lumbar disc herniation with leg weakness. Surgeon comments suggested the utility of injection of the joint for decision making, the merit of predictable outcome with THA first, leg weakness as an indication for spine surgery, the concern of THA position with spinal deformity, and the urgency of myelopathy. Conclusion. With the presence of concurrent hip and spine problems, the question of “THA or lumbar surgery first” remains controversial in certain clinical scenarios, even for experienced hip and spine surgeons. Additional outcome studies of these patients are necessary for appropriate decision making

Sarcopenia has been observed to be a predictor of mortality in international studies of patients with metastatic disease of the spine. This study aimed to validate sarcopenia as a prognostic tool in a New Zealand setting. A secondary aim of this study was to assess the intra-observer reliability of measurements of psoas and vertebral body cross sectional areas on computed tomography imaging. A cohort of patients who had presented to Waikato Hospital with secondary neoplasia in the spinal column from 2014 to 2018 was selected. Cross sectional psoas and vertebral body areas were measured at the mid-pedicle L3 level, followed by calculation of the psoas to vertebral body cross sectional area ratio. Psoas to vertebral body cross sectional area ratio was compared with survivorship. The strength of the correlation between sarcopenia and survivorship was compared with the correlation between serum albumin and survivorship, as well as the correlation between the Metastatic Spine Risk Index (MSRI) and survivorship. A total of 110 patients who received operative (34) and non-operative (76) were included. The results demonstrate that psoas to vertebral body cross sectional area ratio is not statistically significantly correlated with survivorship (p=0.53). Serum albumin is significantly correlated with survivorship (p<0.0001), as was the MSRI. There is good intra-observer and inter-observer reliability for measurements of psoas to vertebral body cross sectional area. This study failed to demonstrate the utility for the psoas to vertebral body cross sectional area ratio that other studies have demonstrated in estimating survivorship. Serum albumin levels remain a useful prognostic indicator in patients with secondary tumours in the vertebral column

Lower back pain (LBP) is a worldwide clinical problem and a prominent area for research. Numerous in vitro biomechanical studies on spine specimens have been undertaken, attempting to understand spinal response to loading and possible factors contributing to LBP. However, despite employing similar testing protocols, there are challenges in replicating in vivo conditions and significant variations in published results. The aim of this study was to use the University of Bath (UoB) spine simulator to perform tests to highlight the major limitations associated with six degree of freedom (DOF) dynamic spine testing. A steel helical spring was used as a validation model and was potted in Wood's metal. Six porcine lumbar spinal motion segments were harvested and dissected to produce isolated spinal disc specimens. These were potted in Wood's metal, ensuring the midplane of the disc remained horizontal and then sprayed with 0.9% saline and wrapped in saline-soaked tissue and plastic wrap to prevent dehydration. A 400N axial preload was used for spinal specimens. Specimens were tested under the stiffness and flexibility protocols. Tests were performed using the UoB custom 6-axis spine simulator with coordinate axes. Tests comprised five cycles with data acquired at 100Hz. Stiffness and flexibility matrices were evaluated from the last three motion cycles using the linear least squares method. According to theory, inverted flexibility matrices should equal stiffness matrices. In the case of the spring, the matrices matched analytical solutions and inverted flexibility matrices were equivalent to stiffness matrices. Matrices from the spinal tests demonstrated some symmetry, with similarities between inverted flexibility- and stiffness matrices, though these were unequal overall. Matrix element values were significantly affected by displacements assumed to occur at disc centre. Spring tests proved that for linear, elastic specimens, the spine simulator functioned as expected. However, multiple factors limit the confidence in spine test results. Centre of rotation, displacement assumptions and rigid body transformations are known to impact the results from spinal testing, and these should be addressed going forward to improve the replication of in vivo conditions

Primary care physicians rely on radiology reports to confirm a scoliosis diagnosis and inform the need for spine specialist referral. In turn, spine specialists use these reports for triage decisions and planning of care. To be a valid predictor of disease and management, radiographic evaluation should include frontal and lateral views of the spine and a complete view of the pelvis, leading to accurate Cobb angle measurements and Risser staging. The study objectives were to determine 1) the adequacy of index images to inform treatment decisions at initial consultation by generating a score and 2) the utility of index radiology reports for appropriate triage decisions, by comparing reports to corresponding images. We conducted a retrospective chart and radiographic review including all idiopathic scoliosis patients seen for initial consultation, aged three to 18 years, between January 1-April 30, 2021. A score was generated based on the adequacy of index images to provide accurate Cobb angle measurements and determine skeletal maturity (view of full spine, coronal=two, lateral=one, pelvis=one, ribcage=one). Index images were considered inadequate if repeat imaging was necessary. Comparisons were made between index radiology report, associated imaging, and new imaging if obtained at initial consultation. Major discrepancies were defined by inter-reader difference >15°, discordant Risser staging, or inaccuracies that led to inappropriate triage decisions. Location of index imaging, hospital versus community-based private clinic, was evaluated as a risk factor for inadequate or discrepant imaging. There were 94 patients reviewed with 79% (n=74) requiring repeat imaging at initial consultation, of which 74% (n=55) were due to insufficient quality and/or visualization of the sagittal profile, pelvis or ribcage. Of index images available for review at initial consult (n=80), 41.2% scored five out of five and 32.5% scored two or below. New imaging showed that 50.0% of those patients had not been triaged appropriately, compared to 18.2% of patients with a full score. Comparing index radiology reports to initial visit evaluation with <60 days between imaging (n=49), discrepancies in Cobb angle were found in 24.5% (95% CI 14.6, 38.1) of patients, with 18.4% (95% CI 10.0, 31.4) categorized as major discrepancies. Risser stage was reported in only 14% of index radiology reports. In 13.8% (n=13) of the total cohort, surgical or brace treatment was recommended when not predicted based on index radiology report. Repeat radiograph (p=0.001, OR=8.38) and discrepancies (p=0.02, OR=7.96) were increased when index imaging was obtained at community-based private clinic compared to at a hospital. Re-evaluation of available index imaging demonstrated that 24.6% (95% CI 15.2, 37.1) of Cobb angles were mis-reported by six to 21 degrees. Most pre-referral paediatric spine radiographs are inadequate for idiopathic scoliosis evaluation. Standardization of spine imaging and reporting should improve measurement accuracy, facilitate triage and decrease unnecessary radiation exposure

Introduction: With a life of over five years, Spine Tango can be considered the first truly International Spine Registry. The Swedish Spine Registry has already shown the feasibility of a registry on a national level. But, there is a need for an international spine registry allowing a benchmarking on an international level. Here we demonstrate the genesis of questionnaire development, the constantly increasing activity, and limitations of the International Spine Registry Spine Tango. Methods: From 2002 until 2007 about 9000 datasets were submitted by 28 hospitals in nine countries worldwide. Three different generations of Spine Tango questionnaires were used for documentation. Results: To cope with varying international administrative issues and legal requirements of data anonymisation, national Spine Tango modules are necessary. Four national Spine Tango modules are in operation to date, another three modules are in the process of roll-out. Considering all these participants, Spine Tango will soon expand to include data from 52 hospitals in 18 countries. One-fourth of these hospitals are University Hospitals, which are destined to take the lead in the Spine Tango registry as opinion leading hospitals. Although the number of participants is steadily growing, no country is yet represented with a sufficient number of hospitals. Indisputably, a marketing concept is needed. An acquisition of new centres via national spine societies seems an obvious strategic approach. Further limitations of Spine Tango include the low number and short duration of follow-ups and the lack of sufficiently detailed patient based data on subgroup level. Discussion: Spine Tango has achieved a firm position as international spine registry and with its increasing acceptance it is also gaining importance. The strengths of Spine Tango include a potentially very large network, the participation of a specialized international society and an academic partner with expertise and extensive experience in registry implementation. Data analysis from Spine Tango is possible but complicated by the incompatibility of generations one and two with the more recent generation three. Consequently findings cannot yet be generalized to any specific country or patient population. Nevertheless, the potential benefits of the project for the whole spine community become increasingly visible. In the near future, the established Spine Tango version three with standardised patient based data will make outcome evaluations possible. In parallel to the International Spine Registry Spine Tango, a National Spine Registry in Australia could be set up – comparable to AOA’s National Joint Replacement Registry

Background. Surgical site infection following spine surgery is associated with increased morbidity, mortality and increased cost for the health care system. The reported pooled incidence is 3%. Perioperative antibiotic prophylaxis is a key factor in lowering the risk of acquiring an infection. Previous studies have assessed perioperative cefuroxime concentrations in the anterior column of the cervical spine with an anterior surgical approach. However, the majority of surgeries are performed in the posterior column and often involve the lumbar spine. Accordingly, the objective was to compare the perioperative tissue concentrations of cefuroxime in the anterior and posterior column of the same lumbar vertebra using microdialysis in an experimental porcine model. Method. The lumbar vertebral column was exposed in 8 female pigs. Microdialysis catheters were placed for sampling in the anterior column (vertebral body) and posterior column (posterior arch) within the same vertebra (L5). Cefuroxime (1.5 g) was administered intravenously over 10 min. Microdialysates and plasma samples were continuously obtained over 8 hours. Cefuroxime concentrations were quantified by Ultra High Performance Liquid Chromatography Tandem Mass Spectrometry. Microdialysis is a catheter-based pharmacokinetic tool, that allows dynamic sampling of unbound and pharmacologic active fraction of drugs e.g., cefuroxime. The primary endpoint was the time with cefuroxime above the clinical breakpoint minimal inhibitory concentration (T>MIC) for Staphylococcus aureus of 4 µg/mL as this has been suggested as the best predictor of efficacy for cefuroxime. The secondary endpoint was tissue penetration (AUC. tissue. /AUC. plasma. ). Results. Mean T>MIC 4 µg/mL (95% confidence interval) was 123 min (105–141) in plasma, 97 min (79–115) in the anterior column and 93 min (75–111) in the posterior column. Tissue penetration (95% confidence interval) was incomplete for both the anterior column 0.48 (0.40–0.56) and posterior column 0.40 (0.33–0.48). Conclusions. Open lumbar spine surgery often involves extensive soft tissue dissection, stripping and retraction of the paraspinal muscles which may impair the local blood flow exposing the lumbar vertebra to postoperative infections. A single intravenous administration of 1.5 g cefuroxime resulted in comparable T>MIC between the anterior and posterior column of the lumbar spine. Mean cefuroxime concentrations decreased below the clinical breakpoint MIC for S. aureus of 4 µg/mL after 123 min (plasma), 97 min (anterior column) and 93 min (posterior column). This is shorter than the duration of most lumbar spine surgeries, and therefore alternative dosing regimens should be considered in posterior open lumbar spine surgeries lasting more than 1.5 hours

Aim. To evaluate efficacy of a one stage posterior approach in decompression and eradication of infection in TB spine. Background. The classic operation for TB spine is anterior spine debridement. This involves a trans-thoracic, or retroperitoneal approach, thus increasing morbidity in an already compromised patient. The anterior procedure in the form of the Hong Kong operation is aimed at decompressing the spine, and debridement of necrotic tissue. If kyphosis is a major problem, its correction requires a posterior procedure, often not at the same sitting. Material and Method. A retrospective review of patients treated surgically for TB Spine during the time period 2009–2012. We examined the records of those patients that were treated by a posterior only approach. We took note of the demographics of the patients. We measured the efficacy of the decompression by measuring the pre op and post op neurologic status as measured by the Frankel grading. The efficacy of debridemide was assessed by measuring the preoperative and follow up ESR. Results. We identified 11 patients for review, 8 male and 3 females. 8 were HIV positive. The disease affected the thoracic spine. The average follow up was 12 months. There was good correction of the deformity and this was maintained throughout the follow up period. The ESR decreased in all the patients. Neurologic improvement was noted in 5 patients and no patients deteriorated. Statistical methods to quantify these changes were not significant because of the small numbers. Conclusion. In our environment a number of patients are immunocompromised by the HIV virus. A trans thoracic approach increases the morbidity in these patients. Effective decompression and debridement can be achieved by the posterior only approach. NO DISCLOSURES

Numerous prediction tools are available for estimating postoperative risk following spine surgery. External validation studies have shown mixed results. We present the development, validation, and comparative evaluation of novel tool (NZSpine) for modelling risk of complications within 30 days of spine surgery. Data was gathered retrospectively from medical records of patients who underwent spine surgery at Waikato Hospital between January 2019 and December 2020 (n = 488). Variables were selected a priori based on previous evidence and clinical judgement. Postoperative adverse events were classified objectively using the Comprehensive Complication Index. Models were constructed for the occurrence of any complication and significant complications (based on CCI >26). Performance and clinical utility of the novel model was compared against SpineSage (. https://depts.washington.edu/spinersk/. ), an extant online tool which we have shown in unpublished work to be valid in our local population. Overall complication rate was 34%. In the multivariate model, higher age, increased surgical invasiveness and the presence of preoperative anemia were most strongly predictive of any postoperative complication (OR = 1.03, 1.09, 2.1 respectively, p <0.001), whereas the occurrence of a major postoperative complication (CCI >26) was most strongly associated with the presence of respiratory disease (OR = 2.82, p <0.001). Internal validation using the bootstrapped models showed the model was robust, with an AUC of 0.73. Using sensitivity analysis, 80% of the model's predictions were correct. By comparison SpineSage had an AUC of 0.71, and in decision curve analysis the novel model showed greater expected benefit at all thresholds of risk. NZSpine is a novel risk assessment tool for patients undergoing acute and elective spine surgery and may help inform clinicians and patients of their prognosis. Use of an objective tool may help to provide uniformity between DHBs when completing the “clinician assessment of risk” section of the national prioritization tool

Surgical site infections (SSIs) after spinal fusion surgery increase healthcare costs, morbidity and mortality. Routine measures of obesity fail to consider site specific fat distribution. We aimed to assess the association between the spine adipose index and deep surgical site infection and determine a threshold value for spine adipose index that can assist in preoperative risk stratification in patients undergoing posterior instrumented lumbar fusion (PILF). A multicentre retrospective case-control study was completed. We reviewed patients who underwent PILF from January 1, 2010 to December 31, 2018. All patients developing a deep primary incisional or organ-space SSI within 90 days of surgery as per US Centre for Disease Control and Prevention criteria were identified. We gathered potential pre-operative and intra-operative deep infection risk factors for each patient. Spine adipose index was measured on pre-operative mid-sagittal cuts of T2 weighted MRI scans. Each measurement was repeated twice by three authors in a blinded fashion, with each series of measurement separated by a period of at least six weeks. Forty-two patients were included in final analysis, with twenty-one cases and twenty-one matched controls. The spine adipose index was significantly greater in patients developing deep SSI (p =0.029), and this relationship was maintained after adjusting for confounders (p=0.046). Risk of developing deep SSI following PILF surgery was increased 2.0-fold when the spine adipose index was ≥0.51. The spine adipose index had excellent (ICC >0.9; p <0.001) inter- and intra-observer reliabilities. The spine adipose index is a novel radiographic measure and an independent risk factor for developing deep SSI, with 0.51 being the ideal threshold value for pre-operative risk stratification in patients undergoing PILF surgery

Abstract. Objectives. Spinal disorders such as back pain incur a substantial societal and economic burden. Unfortunately, there is lack of understanding and treatment of these disorders are further impeded by the inability to assess spinal forces in vivo. The aim of this project is to address this challenge by developing and testing a novel image-driven approach that will assess the forces in an individual's spine in vivo by incorporating information acquired from multimodal imaging (magnetic resonance imaging (MRI) and biplane X-rays) in a subject-specific model. Methods. Magnetic resonance and biplane X-ray imaging are used to capture information about the anatomy, tissues, and motion of an individual's spine as they perform a range of everyday activities. This information is then utilised in a subject-specific computational model based on the finite element method to predict the forces in their spine. The project is also utilising novel machine learning algorithms and in vitro, six-axis mechanical testing on human, porcine and bovine samples to develop and test the modelling methods rigorously. Results & Discussion. MRI sequences have been identified that provide high-quality image data and information on different tissue types which will be used to predict subject-specific disc properties. In-vivo protocols to capture motion analysis, EMG muscle activity, and video X-rays of the spine have been designed with planned data collection of 15 healthy volunteers. Preliminary modelling work has evaluated potential machine learning approaches and quantified the sensitivity of the models developed to material properties. Conclusion. The development and testing of these image-driven subject-specific spine models will provide a new tool for determining forces in the spine. It will also provide new tools for measuring and modelling spine movement and quantifying the properties of the spinal tissues. Acknowledgments. Funding from the EPSRC: EP/V036602/1 (Meakin, Holsgrove & Javadi) and EP/V032275/1 (Holt & Williams). Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

SPINE TANGO is the first International Spine Register. While it has now been fully operational for five years, no results of its collected data have been presented yet. The Swedish Spine Register has already shown that a National Spine Register can generate valid and meaningful data. Here we present data from the first three versions of SPINE TANGO. From 2002 until 2006 about 6000 datasets were submitted by 25 hospitals worldwide. Descriptive analysis was performed for demographic, surgery, and follow-up data comparing all three versions of SPINE TANGO. Over the course of its existence the SPINE TANGO data base showed a rise in median patient age from 52.3 years to 58.6 years and an increasing percentage of degenerative disease as main pathology from 60.1% to 71.4 %. Posterior decompression was the most frequent surgical measure. About one third of all patients had follow-ups. Rehabilitation was arranged more frequently, especially home-based and outpatient rehabilitation. The complication rate was decreasing below 10%. The feasibility of data analysis from the International Spine Register SPINE TANGO could be demonstrated performing descriptive analysis with an evidence level III. In the near future, the meanwhile established SPINE TANGO version 3 with patient based data will make outcome. evaluation possible. This will enable us to present more comprehensive analyses of SPINE TANGO and to make the data base even more beneficial for the whole spine community. In parallel to the International Spine Register SPINE TANGO, a National Spine Register in New Zealand could be set up – comparable to NZOA’s National Joint Register

Abstract. Introduction. Back pain affects 80% of the population at some stage in their life with significant costs to society. Mechanisms and causes of pain have been investigated by studying the behaviour of functional spinal units (FSUs) subjected to displacement- or load control protocols in 6 degrees of freedom (DOF). Load control allows specimens to move physiologically in response to applied loads whereas displacement control constrains motion to individual axes. The displacement control system of the Bath University six-axis spine simulator has been validated and the load control system is in the process of iterative development. Objectives. The objective was to build a computational model of the spine simulator to develop a complete 6 DOF load control system to enable accurate specimen testing under load control. Methods. SolidEdge part files of the simulator assembly exported to MATLAB Simulink® were used to generate a full model of the simulator. Results from displacement tests using a helical spring specimen in the simulator were used to validate the performance of the simulator model in displacement control. The model was then used to develop a 6 DOF load control system including matrix transformations to ensure correct load tracking. Results. Model results for displacement control matched the physical test data within 12% and replicated coupling loads. The developed load control model demonstrated good control in all 6 axes, maintaining zero-commanded loads. Furthermore, peak-to-peak errors in non-zero-commanded loads and moments were below 10% and 15% respectively. Conclusions. The computational model proved a valuable tool in understanding the assembly and functioning of the spine simulator. The in-silico development and validation of the 6 DOF load control system will allow seamless implementation of load control within the spine simulator. The ultimate outcome of this will be the ability to assess the behaviour of FSUs subjected to biofidelic loading conditions

Introduction and Aims: To evaluate open, minimal invasive spine surgery (MISS) with video-assisted thoracoscopic surgery (VATS) using the SynFrame retractor and expandable cages for the anterior reconstruction of thoracic and lumbar spine injuries. Method: Thirty-three consecutive cases of thoracic and lumbar spine pathology requiring anterior reconstruction were analysed. Most patients (90%) underwent prior posterior stabilisation using the Universal Spine System (USS). The thoracic spine was approached by a right-sided mini-thoracotomy, the thoraco-lumbar junction by a left-sided mini-thoracotomy and the lumbar spine by a left-sided mini-retroperitoneal approach using the table-mounted SynFrame retractor system. Fiberoptic endoscopes facilitated illumination and visualisation. The anterior column was reconstructed using expandable cages (Synex) with autologous bone for interbody fusion. Results: Twenty-two males (67%) and 11 females (33%) underwent the procedures. Median age was 38 years (range 19–57). Pathology was trauma in 31 (94%) and tumor in two (6%) cases. Location was thoracic (34%) and lumbar (66%). Mean operating time was 150 minutes (range 75–195 min). Mean blood loss was 0.78 litres. Only three patients needed blood transfusions. Additional bone graft was generated from resected rib or harvested iliac crest in 70% of all cases. There were no visceral/vascular complications, intercostal neuralgia or post-thoracotomy pain syndromes from the minimal access. No anterior reconstruction infections occurred, but there was one superficial and two deep wound infections from the posterior stabilisation. Two cases were abandoned secondary to intercostal vessel bleeding without sequelae. Isolated spine injury cases had mean length of hospital stay of 10 days and return to work at 12 weeks post-operatively. Conclusion: Open, minimal access to the anterior thoracic and lumbar spine is ‘pathology-independent’ and combines the advantages over ‘standard open’ and ‘pure’ endoscopic procedures. Major advantages are direct three-dimensional view of the spine for the surgeon, no need for double-lumen intubation, significant reduction in access morbidity, shorter hospital stay and earlier return to work