En bloc resection for primary bone tumours and isolated metastasis are complex surgeries associated with a high rate of adverse events (AEs). The primary objective of this study was to explore the relationship between frailty/sarcopenia and major perioperative AEs following en bloc resection for primary bone tumours or isolated metastases of the spine. Secondary objectives were to report the prevalence and distribution of frailty and sarcopenia, and determine the relationship between these factors and length of stay (LOS), unplanned reoperation, and 1-year postoperative mortality in this population. This is a retrospective study of prospectively collected data from a single quaternary care referral center consisting of patients undergoing an elective en bloc resection for a primary bone tumour or an isolated spinal metastasis between January 1st, 2009 and February 28th, 2020. Frailty was calculated with the modified frailty index (mFI) and spine tumour frailty index (STFI). Sarcopenia, determined by the total psoas area (TPA) vertebral body (VB) ratio (TPA/VB), was measured at L3 and L4. Regression analysis produced ORs, IRRs, and HRs that quantified the association between frailty/sarcopenia and major perioperative AEs, LOS, unplanned reoperation and 1-year postoperative mortality. One hundred twelve patients met the inclusion criteria. Using the mFI, five patients (5%) were frail (mFI ³ 0.21), while the STFI identified 21 patients (19%) as frail (STFI ³ 2). The mean CT ratios were 1.45 (SD 0.05) and 1.81 (SD 0.06) at L3 and L4 respectively. Unadjusted analysis demonstrated that sarcopenia and frailty were not significant predictors of major perioperative AEs, LOS or unplanned reoperation. Sarcopenia defined by the CT L3 TPA/VB and CT L4 TPA/VB ratios significantly predicted 1-year mortality (HR of 0.32 per one unit increase, 95% CI 0.11-0.93, p=0.04 vs. HR of 0.28 per one unit increase, 95% CI 0.11-0.69, p=0.01) following unadjusted analysis. Frailty defined by an STFI score ≥ 2 predicted 1-year postoperative mortality (OR of 2.10, 95% CI 1.02-4.30, p=0.04). The mFI was not predictive of any clinical outcome in patients undergoing en bloc resection for primary bone tumours or isolated metastases of the spine. Sarcopenia defined by the CT L3 TPA/VB and L4 TPA/VB and frailty assessed with the STFI predicted 1-year postoperative mortality on univariate analysis but not major perioperative AEs, LOS or reoperation. Further investigation with a larger cohort is needed to identify the optimal measure for assessing frailty and sarcopenia in this spine population.
Spinal flexibility in bending and axial torque has been shown to exhibit very modest changes with advancing disc degeneration. This study is the first to address the possible relationship in pure anterior shear and no clear relationship was observed. Disc degeneration (DD) is a risk factor for low back pain. Stable or unstable spine segments may be treated with an isolated decompression or instrumented stabilization, respectively. The effect of DD on spinal flexibility has been addressed by several groups in bending but not in shear; a highly relevant load direction in the lumbar spine is anterior shear. The objective of our study was to determine the effect of DD on anterior translation and specimen stiffness under shear loading in an Summary Statement
Introduction
The aim of this study is to determine evidence-based guidelines on functional outcomes following common thoracolumbar injuries using a synthesis of systematic literature reviews and consensus expert opinion A questionnaire was created comprising five cases representative of common thoracolumbar injuries (a thoracic compression fracture, a flexion distraction injury and burst fractures each with varied location, patient demographics and treatment strategies). For each scenario five questions about expected functional outcomes were posed. Questionnaires were distributed to the Spine Trauma Study Group. Responses were combined with available data from a systematic review of the same injuries and outcomes to create consensus evidence based guidelines. The survey was completed by 31 (57%) of 53 surgeons representing 20 centres across North America. The systematic reviews identified 49 appropriate studies. One year following a L1 burst fracture, a heavy laborer, treated with protective mobilization (cast or brace) has a 40% chance of being pain free, 70% chance of regaining pre-injury range of motion, can expect to be re-employed within 4–6 months and be able to participate in high impact exercise and contact sport with no or minimal limitation. Length of inpatient stay averages 4–5 days. One year following posterior short segment stabilization of a L1 bust fracture in a college football player, there is an expected 45% chance of being pain free and 55% chance of regaining pre-injury ROM. While an ultimate return to high impact exercise and contact sports is anticipated, 32% of experts expect the injury to end a college football career. Results for the other trauma scenarios are included. This combination of literature and expert opinion represents the best available evidence on functional prognosis after thoracolumbar trauma. By providing consistent, accurate information surgeons and other care path providers will help patients develop realistic expectations, which may shape and improve their ultimate outcome.
While there is a desperate need for effective treatments for acute spinal cord injury (SCI), the clinical validation of novel therapeutic interventions is severely hampered by the need to recruit relatively large numbers of patients into clinical trials for sufficient statistical power. While a centre might annually admit 100 acute SCI patients, only a fraction may satisfy the basic inclusion criteria for an acute clinical trial, which typically requires patients of a certain injury severity (eg ASIA A), within a specific time window (eg. 12 hours from injury), and without other major injuries or conditions that would cloud the baseline neurologic assessment. This study was conducted to define that “fraction” of SCI patients that would theoretically satisfy standard inclusion criteria of an acute clinical trial. Using a local database, we reviewed patients admitted to our Level 1 trauma center with a complete (ASIA A) or an incomplete (ASIA B, C and D) acute SCI involving bony spinal levels between C0 and sacrum. All patients admitted over the 4 year period from 2005 to 2009 were reviewed. Demographic information and data about the patients' SCI and other injuries were reviewed. We then determined how many of the total number of SCI patients would be eligible for enrolment into a hypothetical acute clinical trial that required a valid baseline assessment of neurologic impairment, and an enrolment window of either 12 hours, 24 hours, or 48 hours.Introduction
Methods
spinal stenosis; disc degeneration; facet joint arthropathy; or no identifiable pathology. Hospital / University Ethics approval was obtained.
A radio-opaque surrogate cord, with material properties matched to in-vivo specimens, replaced the real spinal cord. Sagittal plane X-rays imaged the surrogate cord in the spine during testing. Varying levels of canal stenosis were simulated by a M8 machine cap screw that entered the canal from the anterior by drilling through the C5 vertebral body. Pure moment loading and a compressive follower load were used to replicate physiologic and super-physiologic motion.
The aetiology of idiopathic scoliosis, despite of long-lasting efforts to disclose it, remains unknown. The purpose of the study was to evaluate the spine development after pinealectomy or cortical sensory motor area damage in the growing rats.
These statistically significant differences were found: higher surgery weight in PIN, longer surgery time in PIN and SMCA, lower lordosis in PIN and higher in CRDU, differences of all groups in kyphosis and in an end weight.
These damages could cause a disorder of balance between smaller inhibitory and greater facilitating area of CNS, controlling the muscular tone and resulting in the development of lordosis and scoliosis due to muscle imbalance.
A biomechanical study assessing pedicle screw fixation with three different augmentation methods was performed in human cadaveric vertebrae. Precision opto-electronic measurement of screw motion assessed motion magnitude and patterns, ie translation and/or rotation. Physiological cyclic loads were applied as opposed to the simple pull out test. Augmentation with wires, hook or cement decreased overall motion. There were no significant differences in motion magnitude between the three augmentation methods. Motion patterns for screws with cement augmentation were mainly rotational and differed from the other two methods. Rigid body translations were observed with wires or hook augmentation, suggesting a loosening behaviour. Augmentation with cement resulted in better fixation than wires or hook. Augmentation of loosened pedicle screws in poor quality bone is often necessary. The purpose of this study was to contrast the kinematics of loosened pedicle screws augmented with laminar hooks, sublaminar wires or calcium phosphate cement. Cyclic tests of pedicle screws with compressive force and bending moment were carried out on forty-eight screws in twenty-four cadaveric vertebrae (L3-L5) augmented with hooks, wires or cement. Motion at the screw tip and screw head were measured using an optoelectronic camera system and the magnitudes compared in a paired manner using non-parametric statistics. Motion patterns of the screws were determined for each augmentation method. Augmentation with hook, wire or cement decreased screw motion. There was no significant difference between augmentation methods when the magnitudes of motion, described as ranges and offsets, were compared. Augmentation with cement resulted in mainly rotations of the screws while there were rigid body translations with wires or hooks. Comparing magnitudes of motion at the screw head and screw tip were insufficient. The screw head and screw tip could be moving in synchronous, indicating rigid body translations. Using simple pull out tests would not detect such differences. The method used in this study contrasted pedicle screws motion with different augmentations. While there was no detected significant difference in motion magnitude of the pedicle screws, the motion pattern of the screws suggested better augmentation with cement. Motion of pedicle screws
Spine Please contact author for diagrams and/or graphs.
The purpose of this study was to investigate the strength profile of the thoracolumbar endplate. Indentation testing was performed on the T9, T12, and L2 endplates of six fresh-frozen human cadaver vertebrae. Indentations were performed in a standardized rectangular grid pattern of seven columns and five rows. There was an incremental increase in the strength of each row moving anterior and posterior from the central row. The relative strength of the anterior regions of the endplate increased with rostral ascent into the thoracic spine. The purpose of this study was to map the strength profile of the thoracolumbar endplates using indentation testing. Indentation testing was performed on the T9, T12, and L2 endplates of six fresh-frozen human cadaver spines using a materials testing machine (Dynamight, Instrom Corporation, Canton, MA). A minimum of twenty-five indentations was performed in a rectangular grid (seven columns by five rows). A 3mm hemispherical indendor was lowered at 0.2mm/s to a depth of 3mm producing endplate failure. The failure load significantly varied with the AP and LAT positions (p<
.0001). Each row was significantly stronger than the rows anterior to it (p <
0.04), except for the most row. The most lateral columns were stronger than the central (range: p = .04 – .0002). The mean strength of the L2 posterior row was greater than that for the thoracic endplates (p<
.01), while no difference existed between levels within the two anterior rows. The ratio of the mean strength for the posterior row compared to that of the anterior row was significantly different across level (P<
0.036). The ratios for L2, T12, and T9 were 1.35, 0.97, and 0.91 respectively. The periphery of the thoracolumbar endplate is stronger than the centre. The interaction identified between position and level suggests a relative strength increase in the anterior aspect of the endplate with rostral ascent into the thoracic spine. This knowledge may assist in preventing intervertebral inplant subsidence by influencing implant positioning and design.
A prospective cohort outcome evaluation of unstable thoracic spine fractures treated with posterior pedicle screw fixation. The purpose of this study was to determine the accuracy of placement and safety of pedicle screws in open reduction of unstable thoracic spine fractures. The surgeries were performed by one of five fellowship trained spinal surgeons. CT scans were formed on twenty-three patients totaling two hundred screws using 3mm cuts. Three independent reviewers assessed and categorized the screw position as within the pedicle or as a violation of the pedicle wall. 98% of the screws were accurate and we recommend the use of pedicle screws in thoracic fractures . A prospective cohort outcome evaluation of unstable thoracic spine fractures treated with posterior pedicle screw fixation. This study is to determine the accuracy of placement, safety of pedicle screws in open reduction of unstable thoracic spine fracture Surgery was performed by one of five fellowship trained spine surgeons. CT scans were performed on twenty-three patients using 3mm cuts in both sagittal and transverse planes. Pedicle screw position was assessed by three independent reviewers. Screw position was categorized as within the wall of the pedicle or in violation of the wall. Further sub-classification of pedicle wall violation reviewed the direction and distance of perforation. Independent perioperative and postoperative surveillance for complications was done. Twenty-three unstable thoracic spine fractures treated with two hundred posterior pedicle screws were analyzed. The pedicle screws spanned from T1-T12 with the majority of screws in the mid-thoracic region. Of the two hundred thoracic pedicle screws placed, 70% were fully contained within the pedicle wall. The remaining screws were deemed “out” with cortical perforation (30%). Of these, 20% were lateral perforations, 5% were medial perforations and 5% were anterolateral perforations. No superior, inferior, or anteromedial perforations were found. There was no regional area variation in incidence of perforations. 10% of all perforations were directly related to pedicle diameter to screw diameter mismatch. There were no adverse neurological, vascular, or visceral injuries detected intraoperatively or postoperatively. Surgical management of unstable thoracic spine fractures with posterior pedicle screw fixation is safe. 98% of screws had satisfactory accuracy. Although very minor misplacement of pedicle screws occurred, there were no complications and we recommend the use of pedicle screws in thoracic fractures.
Spinal cord damage was compared after an injury was inflicted by three clinically relevant mechanisms (contusion, dislocation, and distraction). A novel SCI multi-mechanism system has been developed. Central hemorrhage was common to all mechanisms. Increased membrane permeability was localized to the injury epicenter in contusion but spread further in distraction. Dislocation showed intermediate characteristics exhibiting both local neuronal losses at the epicenter and extended regions of membrane permeability. These preliminary observations suggest that distinct injury mechanisms result in differences in the primary damage of the spinal cord. This work compared primary damage after spinal cord injury (SCI) inflicted by three clinically relevant mechanisms. Different injury mechanisms result in regional differences in damage to the spinal cord. Differences in acute damage may help guide targeted therapies following SCI. At greater distances from the lesion, dextran was excluded from neuronal somata and in the white matter only distinct accumulation was seen at the Nodes of Ranvier. At the injury site, hemorrhage was common to all mechanisms although more diffuse in the distraction injuries. Increased membrane permeability was localized to the injury epicenter in contusion but spread further in distraction. Dislocation showed intermediate characteristics exhibiting both local neuronal losses at the epicenter and extended regions of permeability. A novel SCI multi-mechanism system was developed which uses an electromagnetic actuator to permit the modeling of injuries along any direction. Dextran was infused into the cisterna magna 1.5 to 2 hours prior to injury in order to visualize increases in membrane permeability. Stereotaxic clamps were designed to rigidly hold the lower cervical vertebrae of deeply anaesthetized rats permitting displacements at speeds of 100cm/s. A range of displacements was used in this pilot series: 0.9 to 1.1mm contusion, 2 to 6mm dislocation and 3 to 8mm axial distraction. Animals were sacrificed at five minutes in order to analyse the primary injury. These preliminary observations suggest that distinct injury mechanisms result in regional differences in the primary damage of spinal cord gray and white matter.
This study examined the occurrence of type II (Beta) error in the spine surgical literature. A literature search from 1966 until present identified twenty-nine randomized control trials, which had a two-group parallel design and reported a non-significant difference in the primary outcome measure. We determined whether these trials had sufficient sample size to detect a 25% and 50% relative change in the primary outcome. Nine studies specifically identified a primary outcome. Four studies reported a sample size calculation. Therefore, twenty-five trials were at risk of committing a type II error. The purpose of this study was to determine the frequency of potential type II error in randomized controlled trails reported in the spine surgical literature. A literature search was conducted of the Medline, Pubmed, and the Cochrane databases using the keywords of “spine” and “surgery”, between 1967 until present to identify randomized controlled trials involving spine surgery. Trials were included in this study if they were of a two-group design, with at least one of the groups being a surgical cohort, and that reported a non-significant difference in the primary outcome. We determined the frequency for which the primary outcome and sample size calculation was reported. The sample size was assessed to determine whether the trial had sufficient subjects to detect a 25% and 50% relative difference in the primary outcome for a power of 80%. Twenty-nine studies satisfied the inclusion criteria. Nine studies specifically identified a primary outcome. All others reported multiple outcomes with no specified primary measure. Four studies reported a sample size calculation. Of the remaining twenty-five that did not, three had sufficient power and the rest were at significant risk of committing a type II error. The spine surgical literature is plagued with a high potential for type II errors in the published trails with a non-significant outcome. In the spine surgical literature, a randomized controlled trial that fails to reject its null hypothesis, requires careful scrutiny of its methodology to prevent misinterpretation of the results.
A biomechanical study assessing compressive failure load, strength and stiffness with three different interbody device shapes was performed in human cadaveric vertebrae. The custom-made interbody devices had similar cross-sectional areas and specimens were tested with 20% or 40% coverage of indentor to endplate area. Axial compressive load was applied at 0.2mm/s to a depth equivalent to 20% of the vertebral height. The clover-leaf shaped device resulted in significantly higher failure load, strength and stiffness over the elliptical and the kidney shaped devices for both areas of coverage. The clover-leaf shaped devices extended over stronger periphery regions of the endplates and resulted in stronger interface properties. To determine if two novel interbody cage shapes, the kidney and the clover-leaf, are biomechanically superior to a standard elliptical shape of similar cross sectional area. Uniaxial compression tests with unrestricted rotations were carried out on the superior endplates of forty-eight thoracolumbar (T9-L2) vertebrae with one of three shaped indentors covering 20% or 40% of the endplate area. Compressive load was applied using a servohydraulic testing machine at 0.2mm/s, to depth equivalent to 20% of the vertebral height. Failure load, strength and stiffness were compared. The clover-leaf shaped indentors resulted in higher failure load (53% average increase), higher strength (67% average increase) and higher construct stiffness (43% average increase), and these results were significant (p<
0.05). Larger indentor coverage area of 40% also resulted in significantly higher failure loads over 20% coverage (75% average increase). Current elliptical interbody devices are placed over the central region of the endplate, which is also the weakest. A clover-leaf shaped device extended over the stronger peripheral regions of the endplates and resulted in improved bone-implant interface properties. This implant if implemented in vivo could potentially reduce implant subsidence and lead to better long-term outcomes in osteoporotic patients. The novel clover-leaf shaped indentor displayed superior bone-implant interface properties. Larger interbody devices should be used when possible to improve interface properties. Implant subsidence in osteoporotic patients could be significantly reduced with a clover-leaf shaped device, leading to better long-term outcomes.
Secondary outcomes included the long-term disease-specific HRQOL in these patients, the correlation between radiographic alignment and functional outcome, comparison of HRQOL between operative and non-operative care, and identifying potential prognostic factors influencing functional HRQOL.
Inclusion criteria were age over sixteen, and referral to our center for a traumatic thoracolumbar flexion-distraction injury within two weeks of the injury. Exclusion criteria were an associated spinal cord injury, a previous spine injury or a multi-level spine injury, a significant associated other system injury with an ISS >
50, or patient refusal or inability to complete the outcome questionnaires. Patients were followed for a minimum of two years. Injury classification, healing, and alignment were determined by radiographic analysis. Standing lateral x-rays at final follow-up were used to determine the amount of residual kyphosis by two independent observers.
There were 26 males and 14 females with a mean age of 27.4 years (range 16–48). Average follow-up was 3.3 years (range 2.5–7). Twenty-five patients (64.9%) were treated operatively and fifteen patients (35.1%) underwent non-operative management. Complications in the surgical group included one non-union, three cases of painful instrumentation, and one infection. In the non-surgical group, two patients developed non-unions requiring surgical intervention. Comparing the follow-up mean SF-36 PCS and MCS scores to the recalled baseline SF-36 pre-injury scores, demonstrated the patients did not return to baseline physical component and mental component scores (p <
0.001). The mental component (MCS) and NASS pain scores showed significant statistical difference between the two groups with a trend of non-surgical patients scoring higher. There was no statistically significant difference in the SF-36 PCS between the two groups. Linear and multiple regression models identified “associated other system injuries” as the only useful predictor of outcome influencing the SF-36 PCS. Patients with associated injuries are likely to have a poorer prognosis with lower scores. Radiographically, there was no association between degree of kyphosis at last follow-up and outcome.
Limitations of the study were the retrospective nature of the study, as well as the inherent absence of real time pre-injury quality of life assessment. The study is, however, strengthened by a homogeneous cohort and the use of validated outcome measures. It also involves a cross-sectional analysis and so has a prospective component
There are 20 surviving patients with an average follow up of 41.5 months (range 6 to 111 months), 15 of who had malignant tumors. None of these patients have evidence of local recurrence and one has evidence of systemic disease. The health related quality of life, using the SF-36, shows acceptable morbidity of these procedures (PCS=37.73 ± 11.52, MCS=51.69 ± 9.54).