Hypoglycin A concentrations in seeds of Acer pseudoplatanus trees growing on atypical myopathy-affected and control pastures.

BACKGROUND Hypoglycin A, found in seeds of Acer negundo, appears to cause seasonal pasture myopathy (SPM) in North America and is implicated in atypical myopathy (AM) in Europe. Acer negundo is uncommon in Europe. Thus, the potential source of hypoglycin A in Europe is unknown. HYPOTHESIS AND OBJECTIVES We hypothesized that seeds of Acer pseudoplatanus were the source of hypoglycin A in Europe. Our objective was to determine the concentration of hypoglycin A in seeds of A. pseudoplatanus trees located in pastures where previous cases of AM had occurred. ANIMALS None. METHODS University of Berne records were searched to retrospectively identify 6 farms with 10 AM cases and 11 suspected AM deaths between 2007 and 2011. During October 2012, A. pseudoplatanus seeds were collected from 2 to 6 trees per pasture on 6 AM farms (7 pastures) from trees in or close to 2 pastures on 2 control farms where AM had not been previously reported. Hypoglycin A in seeds was analyzed by GC-MS. RESULTS Acer pseudoplatanus trees were identified on all AM pastures. Hypoglycin A was detected in all A. pseudoplatanus seeds in highly variable concentrations ranging from 0.04 to 2.81 μg/mg (mean 0.69) on AM farms and 0.10 to 9.12 μg/mg (mean 1.59) on control farms. CONCLUSION AND CLINICAL IMPORTANCE Preventing horses from grazing pastures containing A. pseudoplatanus seeds during late fall and early spring might be the best means to prevent AM.

An image-based method to automatically propagate bony landmarks: application to computational spine biomechanics.

In attempts to elucidate the underlying mechanisms of spinal injuries and spinal deformities, several experimental and numerical studies have been conducted to understand the biomechanical behavior of the spine. However, numerical biomechanical studies suffer from uncertainties associated with hard- and soft-tissue anatomies. Currently, these parameters are identified manually on each mesh model prior to simulations. The determination of soft connective tissues on finite element meshes can be a tedious procedure, which limits the number of models used in the numerical studies to a few instances. In order to address these limitations, an image-based method for automatic morphing of soft connective tissues has been proposed. Results showed that the proposed method is capable to accurately determine the spatial locations of predetermined bony landmarks. The present method can be used to automatically generate patient-specific models, which may be helpful in designing studies involving a large number of instances and to understand the mechanical behavior of biomechanical structures across a given population.

Development and validation of a quantitative method to assess pedicle screw loosening in posterior spine instrumentation on plain radiographs.

PURPOSE Currently, the diagnosis of pedicle screw (PS) loosening is based on a subjectively assessed halo sign, that is, a radiolucent line around the implant wider than 1 mm in plain radiographs. We aimed at development and validation of a quantitative method to diagnose PS loosening on radiographs. METHODS Between 11/2004 and 1/2010 36 consecutive patients treated with thoraco-lumbar spine fusion with PS instrumentation without PS loosening were compared with 37 other patients who developed a clinically manifesting PS loosening. Three different angles were measured and compared regarding their capability to discriminate the loosened PS over the postoperative course. The inter-observer invariance was tested and a receiver operating characteristics curve analysis was performed. RESULTS The angle measured between the PS axis and the cranial endplate was significantly different between the early and all later postoperative images. The Spearman correlation coefficient for the measurements of two observers at each postoperative time point ranged between 0.89 at 2 weeks to 0.94 at 2 months and 1 year postoperative. The angle change of 1.9° between immediate postoperative and 6-month postoperative was 75% sensitive and 89% specific for the identification of loosened screws (AUC = 0.82). DISCUSSION The angle between the PS axis and the cranial endplate showed good ability to change in PS loosening. A change of this angle of at least 2° had a relatively high sensitivity and specificity to diagnose screw loosening.

Image-based biomechanical assessment of vertebral body and intervertebral disc in the human lumbar spine

Life expectancy continuously increases but our society faces age-related conditions. Among musculoskeletal diseases, osteoporosis associated with risk of vertebral fracture and degenerative intervertebral disc (IVD) are painful pathologies responsible for tremendous healthcare costs. Hence, reliable diagnostic tools are necessary to plan a treatment or follow up its efficacy. Yet, radiographic and MRI techniques, respectively clinical standards for evaluation of bone strength and IVD degeneration, are unspecific and not objective. Increasingly used in biomedical engineering, CT-based finite element (FE) models constitute the state-of-art for vertebral strength prediction. However, as non-invasive biomechanical evaluation and personalised FE models of the IVD are not available, rigid boundary conditions (BCs) are applied on the FE models to avoid uncertainties of disc degeneration that might bias the predictions. Moreover, considering the impact of low back pain, the biomechanical status of the IVD is needed as a criterion for early disc degeneration. Thus, the first FE study focuses on two rigid BCs applied on the vertebral bodies during compression test of cadaver vertebral bodies, vertebral sections and PMMA embedding. The second FE study highlights the large influence of the intervertebral disc’s compliance on the vertebral strength, damage distribution and its initiation. The third study introduces a new protocol for normalisation of the IVD stiffness in compression, torsion and bending using MRI-based data to account for its morphology. In the last study, a new criterion (Otsu threshold) for disc degeneration based on quantitative MRI data (axial T2 map) is proposed. The results show that vertebral strength and damage distribution computed with rigid BCs are identical. Yet, large discrepancies in strength and damage localisation were observed when the vertebral bodies were loaded via IVDs. The normalisation protocol attenuated the effect of geometry on the IVD stiffnesses without complete suppression. Finally, the Otsu threshold computed in the posterior part of annulus fibrosus was related to the disc biomechanics and meet objectivity and simplicity required for a clinical application. In conclusion, the stiffness normalisation protocol necessary for consistent IVD comparisons and the relation found between degeneration, mechanical response of the IVD and Otsu threshold lead the way for non-invasive evaluation biomechanical status of the IVD. As the FE prediction of vertebral strength is largely influenced by the IVD conditions, this data could also improve the future FE models of osteoporotic vertebra.

Erosive tooth wear: a multifactorial condition of growing concern and increasing knowledge.

Dental erosion is often described solely as a surface phenomenon, unlike caries where it has been established that the destructive effects involve both the surface and the subsurface region. However, besides removal of the surface, erosion shows dissolution of mineral within the softened layer - beneath the surface. In order to distinguish this process from the carious process it is now called 'near surface demineralization'. Erosion occurs in low pH, but there is no fixed critical pH value concerning dental erosion. The critical pH value for enamel concerning caries (pH 5.5-5.7) has to be calculated from calcium and phosphate concentrations of plaque fluid. In the context of dental erosion, the critical pH value is calculated from the calcium and phosphate concentrations in the erosive solution itself. Thus, critical pH for enamel with regard to erosion will vary according to the erosive solution. Erosive tooth wear is becoming increasingly significant in the management of the long-term health of the dentition. What is considered as an acceptable amount of wear is dependent on the anticipated lifespan of the dentition and is, therefore, different for deciduous compared to permanent teeth. However, erosive damage to the teeth may compromise the patient's dentition for their entire lifetime and may require repeated and increasingly complex and expensive restorations. Therefore, it is important that diagnosis of the tooth wear process in children and adults is made early and that adequate preventive measures are undertaken. These measures can only be initiated when the risk factors are known and interactions between them are present.

Comparative effects of teriparatide and ibandronate on spine bone mineral density (BMD) and microarchitecture (TBS) in postmenopausal women with osteoporosis: a 2-year open-label study

UNLABELLED Treatment effects over 2 years of teriparatide vs. ibandronate in postmenopausal women with osteoporosis were compared using lumbar spine bone mineral density (BMD) and trabecular bone score (TBS). Teriparatide induced larger increases in BMD and TBS compared to ibandronate, suggesting a more pronounced effect on bone microarchitecture of the bone anabolic drug. INTRODUCTION The trabecular bone score (TBS) is an index of bone microarchitecture, independent of bone mineral density (BMD), calculated from anteroposterior spine dual X-ray absorptiometry (DXA) scans. The potential role of TBS for monitoring treatment response with bone-active substances is not established. The aim of this study was to compare the effects of recombinant human 1-34 parathyroid hormone (teriparatide) and the bisphosphonate ibandronate (IBN), on lumbar spine (LS) BMD and TBS in postmenopausal women with osteoporosis. METHODS Two patient groups with matched age, body mass index (BMI), and baseline LS BMD, treated with either daily subcutaneous teriparatide (N = 65) or quarterly intravenous IBN (N = 122) during 2 years and with available LS BMD measurements at baseline and 2 years after treatment initiation were compared. RESULTS Baseline characteristics (overall mean ± SD) were similar between groups in terms of age 67.9 ± 7.4 years, body mass index 23.8 ± 3.8 kg/m(2), BMD L1-L4 0.741 ± 0.100 g/cm(2), and TBS 1.208 ± 0.100. Over 24 months, teriparatide induced a significantly larger increase in LS BMD and TBS than IBN (+7.6 % ± 6.3 vs. +2.9 % ± 3.3 and +4.3 % ± 6.6 vs. +0.3 % ± 4.1, respectively; P < 0.0001 for both). LS BMD and TBS were only weakly correlated at baseline (r (2) = 0.04) with no correlation between the changes in BMD and TBS over 24 months. CONCLUSIONS In postmenopausal women with osteoporosis, a 2-year treatment with teriparatide led to a significantly larger increase in LS BMD and TBS than IBN, suggesting that teriparatide had more pronounced effects on bone microarchitecture than IBN.

Necessary or unnecessary? a critical glance on spine surgery

Patients with complaints and symptoms caused by spinal degenerative diseases demonstrate a high rate of spontaneous improvement. Except of severe neurological symptoms such as high grade motor deficits, medically intractable pain and vegetative symptoms (cauda syndrome) operations require 1) symptoms, 2) a mechanical cause visible on imaging that sufficiently explains the symptoms, 3) a completed conservative treatment protocol performed over a 4) 6-12 week period. According to the evidence found in the literature, patients with lumbar disk herniation significantly benefit from surgery by a faster relieve of pain and return to social and professional activity, however, the results are converging after a period of 1-2 years. Surgery of lumbar spinal stenosis is considered a gold standard and superior to conservative care when symptoms are severe and leg pain is present. Bilateral microsurgical decompression using a bilateral or a unilateral approach with over-the-top decompression of the contralateral nerve root are superior to laminectomy as the decompression procedure. Lumbar fusion is only indicated in patients with spinal stenosis when a major or mobile spondylolisthesis is diagnosed. There is no indication of prophylactic surgery to avoid a "dangerous" deficit that might develop in the future.

Patient-rated Outcomes of Lumbar Fusion in Patients with Degenerative Disease of the Lumbar Spine: Does Age Matter?

Introduction: Current demographic changes are characterized by population aging, such that the surgical treatment of degenerative spine conditions in the elderly is gaining increasing relevance. However, there is a general reluctance to consider spinal fusion procedures in this patient age group due to the increased likelihood of complications. The aim of this study was to assess the patient-rated outcome and complication rates associated with lumbar fusion procedures in three different age groups. Methods: This was a retrospective analysis of prospectively collected data from consecutive patients who underwent first-time, one to three level posterior instrumented fusion between 2004 and 2011, due to degenerative disease of the lumbar spine. Data were obtained from our Spine Surgery Outcomes Database (linked to the International Spine Tango Register). Before surgery, patients completed the multidimensional Core Outcome Measures Index (COMI), and at 3 and 12 months after surgery they completed the COMI and rated the Global Treatment Outcome (GTO) and their satisfaction with care. Patients were divided into three groups according to their age: younger (≥50y <65y; n = 317), older (≥65y <80y; n = 350), and geriatric (≥ 80y; n = 40). Results: 707 consecutive patients were included. The preoperative comorbidity status differed significantly (p < 0.0001) between the age groups, with the highest scores in the geriatric group. General medical complications during surgery were lower in the younger age group (7%) than in the older (13.4%; p = 0.006) and geriatric groups (17.5%; p = 0.007). Duration of hospital stay was longer (p = 0.006) in the older group (10.8 ± 3.7 days) than the younger (10.0 ± 3.6 days) group. There were no significant group differences (p>0.05) for any of the COMI domains covering pain, function, symptom specific well-being, general quality of life, and social and work disability at either 3 months’ or 12 months’ follow-up. Similarly, there were no differences (p>0.05) between the age groups for GTO and patient-rated satisfaction at either follow-up. Conclusions: Preoperative comorbidity and general medical complications during lumbar fusion for degenerative disorders of the lumbar spine are both greater in geriatric patients than in younger patients. However, patient-rated outcome is as good in the elderly as it is in younger age groups. These data suggest that geriatric age per se is not a contraindication to instrumented fusion for lumbar degenerative disease.

Factor analysis of the North American Spine Society outcome assessment instrument: a study based on a spine registry of patients treated with lumbar and cervical disc arthroplasty.

Background context Studies involving factor analysis (FA) of the items in the North American Spine Society (NASS) outcome assessment instrument have revealed inconsistent factor structures for the individual items. Purpose This study examined whether the factor structure of the NASS varied in relation to the severity of the back/neck problem and differed from that originally recommended by the developers of the questionnaire, by analyzing data before and after surgery in a large series of patients undergoing lumbar or cervical disc arthroplasty. Study design/setting Prospective multicenter observational case series. Patient sample Three hundred ninety-one patients with low back pain and 553 patients with neck pain completed questionnaires preoperatively and again at 3 to 6 and 12 months follow-ups (FUs), in connection with the SWISSspine disc arthroplasty registry. Outcome measures North American Spine Society outcome assessment instrument. Methods First, an exploratory FA without a priori assumptions and subsequently a confirmatory FA were performed on the 17 items of the NASS-lumbar and 19 items of the NASS-cervical collected at each assessment time point. The item-loading invariance was tested in the German version of the questionnaire for baseline and FU. Results Both NASS-lumbar and NASS-cervical factor structures differed between baseline and postoperative data sets. The confirmatory analysis and item-loading invariance showed better fit for a three-factor (3F) structure for NASS-lumbar, containing items on “disability,” “back pain,” and “radiating pain, numbness, and weakness (leg/foot)” and for a 5F structure for NASS-cervical including disability, “neck pain,” “radiating pain and numbness (arm/hand),” “weakness (arm/hand),” and “motor deficit (legs).” Conclusions The best-fitting factor structure at both baseline and FU was selected for both the lumbar- and cervical-NASS questionnaires. It differed from that proposed by the originators of the NASS instruments. Although the NASS questionnaire represents a valid outcome measure for degenerative spine diseases, it is able to distinguish among all major symptom domains (factors) in patients undergoing lumbar and cervical disc arthroplasty; overall, the item structure could be improved. Any potential revision of the NASS should consider its factorial structure; factorial invariance over time should be aimed for, to allow for more precise interpretations of treatment success.

Influencing factors on the length of stay in lumbar spine surgery: analysis of the German spine registry

INTRODUCTION Spinal disc herniation, lumbar spinal stenosis and spondylolisthesis are known to be leading causes of lumbar back pain. The cost of low back pain management and related operations are continuously increasing in the healthcare sector. There are many studies regarding complications after spine surgery but little is known about the factors predicting the length of stay in hospital. The purpose of this study was to identify these factors in lumbar spine surgery in order to adapt the postoperative treatment. MATERIAL AND METHODS The current study was carried out as a post hoc analysis on the basis of the German spine registry. Patients who underwent lumbar spine surgery by posterior surgical access and with posterior fusion and/or rigid stabilization, whereby procedures with dynamic stabilization were excluded. Patient characteristics were tested for association with length of stay (LOS) using bivariate and multivariate analyses. RESULTS A total of 356 patients met the inclusion criteria. The average age of all patients was 64.6 years and the mean LOS was 11.9 ± 6.0 days with a range of 2-44 days. Independent factors that were influencing LOS were increased age at the time of surgery, higher body mass index, male gender, blood transfusion of 1-2 erythrocyte concentrates and the presence of surgical complications. CONCLUSION Identification of predictive factors for prolonged LOS may allow for estimation of patient hospitalization time and for optimization of postoperative care. In individual cases this may result of a reduction in the LOS.

Dendritic spine morphology determines membrane-associated protein exchange between dendritic shafts and spine heads.

The purpose of this study was to examine whether variability in the shape of dendritic spines affects protein movement within the plasma membrane. Using a combination of confocal microscopy and the fluorescence loss in photobleaching technique in living hippocampal CA1 pyramidal neurons expressing membrane-linked GFP, we observed a clear correlation between spine shape parameters and the diffusion and compartmentalization of membrane-associated proteins. The kinetics of membrane-linked GFP exchange between the dendritic shaft and the spine head compartment were slower in dendritic spines with long necks and/or large heads than in those with short necks and/or small heads. Furthermore, when the spine area was reduced by eliciting epileptiform activity, the kinetics of protein exchange between the spine compartments exhibited a concomitant decrease. As synaptic plasticity is considered to involve the dynamic flux by lateral diffusion of membrane-bound proteins into and out of the synapse, our data suggest that spine shape represents an important parameter in the susceptibility of synapses to undergo plastic change.

Clinical Use of Quantitative Computed Tomography–Based Finite Element Analysis of the Hip and Spine in the Management of Osteoporosis in Adults: the 2015 ISCD Official Positions—Part II

The International Society for Clinical Densitometry (ISCD) has developed new official positions for the clinical use of quantitative computed tomography (QCT)-based finite element analysis of the spine and hip. The ISCD task force for QCT reviewed the evidence for clinical applications and presented a report with recommendations at the 2015 ISCD Position Development Conference. Here we discuss the agreed upon ISCD official positions with supporting medical evidence, rationale, controversy, and suggestions for further study. Parts I and III address the clinical use of QCT of the hip, and the clinical feasibility of existing techniques for opportunistic screening of osteoporosis using CT scans obtained for other diagnosis such as colonography was addressed.

Metamorphosis of human lumbar vertebrae induced by VEPTR growth modulation and stress shielding

INTRODUCTION Distraction-based spinal growth modulation by growing rods or vertical expandable prosthetic titanium ribs (VEPTRs) is the mainstay of instrumented operative strategies to correct early onset spinal deformities. In order to objectify the benefits, it has become common sense to measure the gain in spine height by assessing T1-S1 distance on anteroposterior (AP) radiographs. However, by ignoring growth changes on vertebral levels and by limiting measurement to one plane, valuable data is missed regarding the three-dimensional (3D) effects of growth modulation. This information might be interesting when it comes to final fusion or, even more so, when the protective growing implants are removed and the spine re-exposed to physiologic forces at the end of growth. METHODS The goal of this retrospective radiographic study was to assess the growth modulating impact of year-long, distraction-based VEPTR treatment on the morphology of single vertebral bodies. We digitally measured lumbar vertebral body height (VBH) and upper endplate depth (VBD) at the time of the index procedure and at follow-up in nine patients with rib-to-ileum constructs (G1) spanning an anatomically normal lumbar spine. Nine patients with congenital thoracic scoliosis and VEPTR rib-to-rib constructs, but uninstrumented lumbar spines, served as controls (G2). All had undergone more than eight half-yearly VEPTR expansions. A Wilcoxon signed-rank test was used for statistical comparison of initial and follow-up VBH, VBD and height/depth (H/D) ratio (significance level 0.05). RESULTS The average age was 7.1 years (G1) and 5.2 year (G2, p > 0.05) at initial surgery; the average overall follow-up time was 5.5 years (p = 1). In both groups, VBH increased significantly without a significant intergroup difference. Group 1 did not show significant growth in depth, whereas VBD increased significantly in the control group. As a consequence, the H/D ratio increased significantly in group 1 whereas it remained unchanged in group 2. The growth rate for height in mm/year was 1.4 (group 1) and 1.1 (group 2, p = 0.45), and for depth, it was -0.3 and 1.1 (p < 0.05), respectively. CONCLUSIONS VEPTR growth modulating treatment alters the geometry of vertebral bodies by increasing the H/D ratio. We hypothesize that the implant-related deprivation from axial loads (stress-shielding) impairs anteroposterior growth. The biomechanical consequence of such slender vertebrae when exposed to unprotected loads in case of definitive VEPTR removal at the end of growth is uncertain.