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Purpose A major challenge in metastatic spinal disease is timely identification of patients. Left untreated, spinal metastases may lead to gross mechanical instability and/or neurological deficits, often requiring extensive invasive surgical treatment. The aim of this cohort study was to assess the correlation between delayed treatment of patients with spinal metastases and functional performance, quality of life and survival. Methods All patients surgically treated for metastatic spinal disease at a tertiary care facility were included for analysis. Patients who underwent elective surgery were considered as timely treated, whereas patients requiring emergency surgery were considered to be treated in a delayed fashion. EQ-5D scores, KPS scores and mortality rates were compared between the two groups. Results A total of 317 patients (215 timely treated, 102 delayed) had survivorship data available and 202 patients (147 timely treated, 55 delayed) had clinical data available. Multivariate analyses showed delayed treatment was associated with lower EQ-5D and KPS scores and higher mortality rates, independent of confounders such as baseline EQ-5D/KPS scores, neurological status, tumor prognosis and patient age. Conclusions The results from the present study show delayed treatment of patients with symptomatic spinal metastases has both direct and indirect adverse consequences for functional performance status, quality of life and survival. Optimization of referral pattern may accelerate the time to surgical treatment, potentially leading to better quality of life and survival.

Purpose: An excessive amount of total hospitalization is caused by delays due to patients waiting to be placed in a rehabilitation facility or skilled nursing facility (RF/SNF). An accurate preoperative prediction of who would need a RF/SNF place after surgery could reduce costs and allow more efficient organizational planning. We aimed to develop a machine learning algorithm that predicts non-home discharge after elective surgery for lumbar spinal stenosis. Methods: We used the American College of Surgeons National Surgical Quality Improvement Program to select patient that underwent elective surgery for lumbar spinal stenosis between 2009 and 2016. The primary outcome measure for the algorithm was non-home discharge. Four machine learning algorithms were developed to predict non-home discharge. Performance of the algorithms was measured with discrimination, calibration, and an overall performance score. Results: We included 28,600 patients with a median age of 67 (interquartile range 58–74). The non-home discharge rate was 18.2%. Our final model consisted of the following variables: age, sex, body mass index, diabetes, functional status, ASA class, level, fusion, preoperative hematocrit, and preoperative serum creatinine. The neural network was the best model based on discrimination (c-statistic = 0.751), calibration (slope = 0.933; intercept = 0.037), and overall performance (Brier score = 0.131). Conclusions: A machine learning algorithm is able to predict discharge placement after surgery for lumbar spinal stenosis with both good discrimination and calibration. Implementing this type of algorithm in clinical practice could avert risks associated with delayed discharge and lower costs. Graphical abstract: These slides can be retrieved under Electronic Supplementary Material.[Figure not available: see fulltext.].

In their work C. Bouza and coauthors present the results from a systematic review conducted to ‘analyze the collected body of evidence regarding the efficacy and safety on balloon kyphoplasty in the treatment of vertebral compression fractures’. The authors conclude from their work that balloon kyphoplasty seems effective and safe. It is generally accepted that, in the absence of conclusive results from methodological rigorous studies, a systematic review can increase the accuracy of estimated treatment effect by pooling previously published data [1]. The authors have chosen to evaluate a relatively new minimal invasive technique using a systematic review as research tool, which makes good sense since large-scale randomized controlled trials on this subject are absent while interest in balloon kyphoplasty is considerable, having led to lively debate on multiple occasions. One of the most interesting topics under discussion is the difference of kyphoplasty versus vertebroplasty versus medical therapy for the treatment of vertebral compression fractures in terms of indications, outcome, complications and cost effectiveness. Following preliminary publications reporting success with kyphoplasty and vertebroplasty compared to medical therapy for vertebral compression fractures, both techniques seem to have been embraced and promoted by their respective advocates with uncontrolled case-series and anecdotes put forward as evidence. Although preliminary data from new techniques obtained from low level of evidence studies can certainly be interesting to discover potential benefits and/or pitfalls, it will not lead to proof of effectiveness. The spine community is unfortunate to have witnessed the introduction of numerous (surgical) techniques without proper controlled unbiased investigation of their merits. The ongoing controversy about the optimal treatment of traumatic thoracolumbar fractures, initiated more than 20 years ago and unlikely to be solved in the coming twenty, serves as a good example of what can happen without careful early evaluation of a new type of treatment. Vertebroplasty and kyphoplasty are recent examples of this practice and, with respect to the availability of evidence of their effectiveness and/or safety, we are in the dark. Conclusive statements on the performance of these new techniques must be regarded invalid if not backed up by solid data from methodological sound studies. Acknowledging the lack of good quality clinical trials, the present authors have taken a different route to find evidence and combined data from existing material to achieve better estimates of effect. The quality of a systematic review, and therewith the strength of its conclusions and recommendations, is directly dependent on the methodological quality of the studied material. Some limitations of the present study become apparent after close review of the primary papers. Critical quality parameters such as study design, duration of follow up, number of patients lost to follow up, validation of outcome parameters point to grade IV level of evidence instead of the grade II–III as suggested by the authors (http://www.cebm.net/levels_of_evidence.asp). The authors seem to have overestimated the quality of the material under investigation which is surprising for a study aiming to find evidence. Although the authors do an excellent job of recognizing the limitations of their work in the discussion section, they do not succeed in eliminating all bias when assessing the papers their manuscript is based on. This is something the reader should keep in mind when reading the article and contemplating the conclusions. In the end, I think this work is a good summary of the available papers describing balloon kyphoplasty for vertebral compression fractures but I am not sure if it has advanced the field besides stressing once more the necessity of high quality clinical research.

Besides a patient reported outcome measure, the AOSpine Knowledge Forum Trauma aims to develop a new concept of a surgeon reported outcome measure (SROM) for spine trauma patients. This study aims to identify parameters that spine surgeons consider relevant to evaluate clinical and functional outcomes of thoracic and lumbar spine trauma patients. An international cross-sectional web-based survey was conducted among spine surgeons from the five AOSpine International world regions. They were asked to evaluate the relevance of a compilation of 16 clinical and radiological parameters for thoracic and lumbar spine trauma patients, both for the short term (3 months–2 years) and long term (≥2 years), on a five-point scale. The responses were analyzed using descriptive statistics, frequency analysis, and Kruskal–Wallis test. Out of the 279 invited members of AOSpine International and the International Spinal Cord Society, 118 (42.3 %) participated in this study. Of the 16 surveyed parameters, 5 were identified as relevant by at least 70 % of the participants. Neurological status was identified as most relevant. In contrast, five parameters were not deemed relevant for any spine region or time period, except for comorbidity. Only minor differences were observed when analyzing the responses according to each world region, spine surgeons’ clinical experience, or professional background. Including a large and representative sample of spine trauma experts, this study identified parameters to evaluate clinical and functional outcomes of thoracic and lumbar spine trauma patients. The results form the basis for the development of a SROM for this specific patient population.

Diffuse idiopathic skeletal hyperostosis (DISH) is a common but often unrecognized systemic disorder observed mainly in the elderly. DISH is diagnosed when the anterior longitudinal ligament of the spine is ossified on at least four contiguous spinal levels or when multiple peripheral enthesopathies are present. The etiology of DISH is unknown but previous studies have shown a strong association with obesity and insulin-independent diabetes mellitus. DISH can lead to back pain, dysphagia, myelopathy, musculoskeletal impairment and grossly unstable spine fractures after minor trauma. In archeological studies a high prevalence of DISH has been demonstrated in ancient clergymen. The present study describes the pathological changes of human remains excavated from the abbey court (Pandhof) in the city of Maastricht, The Netherlands. Human remains of 51 individuals buried between 275 and 1795 CE: were excavated and examined. The remains were investigated according to a standardized physical anthropological report and individuals demonstrating ossification of spinal ligaments and/or multiple peripheral enthesopathies were included in the study group. The authors reviewed all available material and after reaching consensus, each abnormality found was given a diagnosis and subsequently recorded. After examination, 28 individuals were considered to be adult males; 11 adult females; three adults of indeterminate sex and nine individuals were of sub adult age. The mean age at death for adults was 36.8 years. Seventeen adult individuals (40.4% of all adults), displayed ossifications of at least four contiguous spinal levels and/or multiple enthesopathies of the appendicular skeleton and were therefore, assigned the diagnosis DISH. The mean age of these individuals was 49.5 +/- 13.0 years. In at least three of these individuals, DISH had led to extensive ossification and subsequent ankylosis of axial and peripheral skeletal structures. In this population of (presumably) clergymen and high-ranking citizens, DISH was observed in unusual high numbers at a relatively young age. Some of the examined cases suggest that DISH may be a seriously incapacitating disorder when the more advanced stages of the disease have been reached. It is hypothesized that "a monastic way of life" can predispose to DISH. Present demographic trends in obesity and diabetes mellitus as potential co-factors for the development of DISH warrant further study to investigate its future prevalence.

Diffuse idiopathic skeletal hyperostosis (DISH) is a systemic disorder of the axial and peripheral skeleton in humans and has incidentally been described in dogs. The aims of this retrospective radiographic cohort study were to determine the prevalence of DISH in an outpatient population of skeletally mature dogs and to investigate if dogs can be used as an animal model for DISH. The overall prevalence of canine DISH was 3.8% (78/2041). The prevalence of DISH increased with age and was more frequent in male dogs, similar to findings in human studies. In the Boxer breed the prevalence of DISH was 40.6% (28/69). Dog breeds represent closed gene pools with a high degree of familiar relationship and the high prevalence in the Boxer may be indicative of a genetic origin of DISH. It is concluded that the Boxer breed may serve as an animal model for DISH in humans.

In their work colleagues Nottmeier and Foy present a retrospective series of eight patients treated with posterior C1–C2 fusion by laminar screws using three-dimensional fluoroscopy-based image guidance. They conclude from the results of their work that: “In this study, it has been shown that C2 laminar screws can be safely and accurately placed using 3D fluoroscopy-based image guidance. Advantages of this technology over traditional techniques include real-time 3D computerized feedback to the surgeon during placement, as well as the ability to size the screw to the patient’s anatomy using intraoperative computerized planning.” In the last decade, technology has advanced to the point where regular computer workstations are able to calculate in real-time the transformation matrices needed to determine the position of a camera-tracked object (in a surgical setting, typically a frame with fiducials) in relation to a camera-tracked reference base. By attaching the reference base to a patient and (surgical) instruments to camera-tracked objects, the workstation can calculate the respective positions/orientations and display their virtual interactions. When three-dimensional data sets representing the patient’s anatomy from modalities including CT/MRI/3D rotational X-ray imaging, are manipulated so that virtual and real reference bases are exactly aligned, surgical instruments and/or implants can be displayed on anatomical structures not visible for the surgeon intraoperatively. This is, in a nutshell, current “computer-assisted surgery” or “image-guided surgery”. Assuming that transformation matrix calculations are mathematical processes carried out with high fidelity and great reproducibility, imperfections in navigational accuracy must have other sources. Calibration errors in 3D fluoroscopy-based systems have, for example, been shown to account for approximately 1 mm accuracy in a phantom model [1]. In a more realistic cadaveric model, the accuracy of navigation deteriorated to approximately 2.5 mm, mainly due to bending of instruments and/or references during manipulation [2]. In clinical practice more inaccuracies can be introduced by occasional blocking of the camera field of view; inadvertently touching/hitting references and, especially, a nonrigid connection between the patient reference base and the actual surgical site. In the present study, the patient reference base was attached to a head clamp, which was, in turn, connected via pins to the patient’s skull while surgery was performed at the levels C1 and C2. This experimental setup represents quite a long chain of connections from the reference base to the surgical site with considerable opportunity for movement between the two extremes. This is without taking into account additional movements due to, for example, patient ventilation and direct manipulation of C1 and C2 by surgical instruments. Considering that the C0–C1–C2 complex is highly mobile, it came as a small surprise for this reviewer to find such accurate screw placement in the current study. As can be found in the article, the investigators did verify the image-guided technique (“After accuracy of navigation was confirmed by the surgeon ... ”). The interesting question that follows automatically is: “How?” Checking accuracy by probing the patient reference base with a navigated instrument and finding a perfectly matched position/orientation on the computer display does nothing for the flexibility/movement errors that may be present at the more distant surgical site. Most often, surgeons verify accuracy by a direct intraoperative view of the surgical site to see whether, for example, the proposed drill trajectory or planned screw length is in accordance to their own experience from conventional surgeries before moving on with navigation. This leads to the strange paradox that is really bugging contemporary image-guided procedures: the employment of a technique to enhance surgical accuracy requiring the surgeon’s intraoperative verification of its accuracy. The reluctance of surgeons to show complete faith in image guidance seems justified considering the errors demonstrated in accuracy studies. Using computer navigation without proper anatomical and surgical knowledge would be irresponsible. Armed with proper knowledge, however, navigation becomes largely superfluous since surgeons trust their surgical experience/skills and the direct intraoperative view over computer-generated images anytime, and adjust their actions accordingly. Which surgeon would happily volunteer when asked to perform a percutaneous procedure having to trust solely on information provided by any image-guided technique commercially available today? Until now, no large-scale long-term and properly controlled study has been published in the field of computer-assisted surgery that has convincingly showed any actual patient benefit when using image guidance. Lacking a control group and using a navigation technique susceptible to the aforementioned accuracy problems, the present study may, unfortunately, not be able to change this status.