Adjacent Vertebrae Research Articles

A Smart Technique to Remove Ruptured Inflatable Bone Tamp From the Vertebral Body in Balloon Kyphoplasty.

Accidental rupture of the inflatable bone tamp is a rare but possible complication during balloon kyphoplasty. We describe an easy and minimal invasive technique to remove this foreign body from fractured vertebra. A 62-year-old female patient with severe osteoporosis had a low energy trauma and sustained burst fracture of the 12th thoracic (Th12) vertebra. The inflated bone tamp was not possible to be fully deflated and during the maneuvers to withdraw the balloon, it was disassembled and trapped under the distal end of working cannula, remaining within the bone cavity formed by balloon. Since no standard recommendation for this complication exists in current literature, we faced the dilemma of either leaving ruptured bone tamp in situ or removing it with a more extensive approach. We decided to use an alternative minimal invasive technique and managed to remove it through the right pedicle using a small size straight pituitary rongeur forceps under biplane continuous image intensifier and neuromonitoring. Subsequently, balloon kyphoplasty (BK) was performed through the left cannula accompanied with pedicle screw fixation of the adjacent vertebrae. The patient was followed up to our outpatient department for one year without complications. This extremely rare complication during BK consists of a challenge for spine surgeons and interventional radiologists. The described technique is relatively easy, safe, minimal invasive, time-saving and avoids further complications related with trapping of foreign bodies within the vertebral body.

Comparison of Functional and Radiological Outcomes of Transforaminal Lumbar Interbody Fusion and Posterolateral Fusion Techniques in the Treatment of Lumbar Spinal Stenosis.

This study aimed to compare posterolateral fusion with transforaminal lumbar interbody fusion (PLF + TLIF) and PLF only in terms of revision surgery rates and complications, as well as functional and radiological outcomes in lumbar spinal stenosis (LSS) patients. Seventy-one patients (37 patients in the PLF + TLIF group and 34 patients in the PLF only group) who underwent surgery due to LSS between January 2013 and December 2016 were retrospectively investigated. Functional evaluation was performed by using the McGill-Melzack Pain Questionnaire (MPQ), Roland Morris Disability Questionnaire (RMDQ), and Oswestry Disability Index (ODI) scales pre-and postoperatively. Radiological evaluation was made by examining adjacent vertebrae, posterior ligamentous complex (PLC) morphology, and sagittal balance on magnetic resonance imaging (MRI). Postoperative MPQ, RMDQ, and ODI scores were significantly better in the PLF + TLIF group (p < 0.001, p < 0.001, and p = 0.001, respectively). The complication rate was significantly higher in the PLF only group (p = 0.026). In the PLF + TLIF group, postoperative functional scores showed significant improvement in terms of the instrumented segment and level of interbody fusion. Postoperative functional scores showed significant improvement in PLF + TLIF patients with no complications, no revision surgery, no postoperative MRI findings, and neutral sagittal balance compared to the preoperative functional scores (p < 0.001). PLF + TLIF is significantly superior in terms of functional scores and complications, despite the statistical similarity in terms of postoperative MRI findings and sagittal balance between the groups. Surgeons should prefer PLF + TLIF for the surgical treatment of LSS for better results.

Two-Stream Compare and Contrast Network for Vertebral Compression Fracture Diagnosis.

Differentiating Vertebral Compression Fractures (VCFs) associated with trauma and osteoporosis (benign VCFs) or those caused by metastatic cancer (malignant VCFs) is critically important for treatment decisions. So far, automatic VCFs diagnosis is solved in a two-step manner, i.e., first identify VCFs and then classify them into benign or malignant. In this paper, we explore to model VCFs diagnosis as a three-class classification problem, i.e., normal vertebrae, benign VCFs, and malignant VCFs. However, VCFs recognition and classification require very different features, and both tasks are characterized by high intra-class variation and high inter-class similarity. Moreover, the dataset is extremely class-imbalanced. To address the above challenges, we propose a novel Two-Stream Compare and Contrast Network (TSCCN) for VCFs diagnosis. This network consists of two streams, a recognition stream which learns to identify VCFs through comparing and contrasting between adjacent vertebrae, and a classification stream which compares and contrasts between intra-class and inter-class to learn features for fine-grained classification. The two streams are integrated via a learnable weight control module which adaptively sets their contribution. TSCCN is evaluated on a dataset consisting of 239 VCFs patients and achieves the average sensitivity and specificity of 92.56% and 96.29%, respectively.

Cement bridging phenomenon in percutaneous vertebroplasty for adjacent vertebral compression fracture

In some cases of vertebroplasty for adjacent fractures, we observed a cement bridging phenomenon, in which the injected cement flowed from the newly fractured vertebra to the previously cement-augmented vertebra through the space between the abutting anterior longitudinal ligament and the vertebral column. The purpose of this retrospective study was to investigate this phenomenon. From January 2012 to December 2014, patients who sustained new-onset adjacent vertebral compression fracture and who were again treated with vertebroplasty were enrolled. We divided the patients into two groups, the bridging group and the nonbridging group, to analyze the difference between them. Results showed that the cement bridging phenomenon occurred in 18 (22.8%) of the 79 patients. Significant differences between the bridging and nonbridging groups were identified in the following 3 imaging features: severe loss of the anterior vertebral body height at the new-onset adjacent vertebra on plain film (odds ratio [OR] = 4.46, p = 0.014), fluid accumulation (OR = 36.27, p < 0.001) and hypointense signaling (OR = 15.67, p < 0.001) around the space anterior to the abutting vertebral bodies and the corresponding intervertebral disc on MRI. After a 2-year follow-up, both the mean value of the focal kyphotic angle and anterior body height ratio were significantly better in the cement bridging group than in the nonbridging group. The cement bridging phenomenon, which has never been reported in the literature, is not rare in clinical practice. This phenomenon was associated with better maintenance of focal kyphotic angle and anterior body height ratio during the 2-year follow-up.

Association of Continuous Vertebral Bone Bridges and Bone Mineral Density with the Fracture Risk in Patients with Diffuse Idiopathic Skeletal Hyperostosis.

Study DesignCross-sectional study.PurposeTo examine whether the number of continuous vertebral bone bridges and bone mineral density (BMD) influence the fracture risk in diffuse idiopathic skeletal hyperostosis (DISH) patients.Overview of LiteratureBone bridges connecting through the intervertebral body in DISH create long lever arms that can increase the risk of fractures from minor trauma. DISH patients have a BMD that is higher than or comparable to those of age-matched healthy subjects.MethodsWe examined the computed tomography scans from the thoracic vertebra to the sacrum used to diagnose DISH in 140 patients (98 men and 42 women; average age, 78.6 years). We compared patients who did (n=52) and did not have (n=88) fractures at the continuous vertebral bodies fused by bone bridges. The relationship between the vertebral fractures and the maximum number of vertebrae that are bony cross-linked with contiguous adjacent vertebrae (max VB) from the thoracic vertebra to the sacrum or from the lumbar vertebra to the sacrum and proximal femur BMD were analyzed using a logistic regression model.ResultsWe found that after adjusting for the confounding factors, higher max VB, both from the thoracic vertebrae to the sacrum and the lumbar vertebrae to the sacrum, was associated with a higher risk of vertebral fractures. This difference was statistically significant. The risk was higher when only the lumbar vertebrae to the sacrum was considered (thoracic vertebrae to the sacrum: odds ratio, 1.21; p<0.05; lumbar vertebrae to the sacrum: odds ratio, 2.78; p<0.01). Moreover, low proximal femur BMD in DISH patients raises the fracture risk (odds ratio, 0.47; p<0.01).ConclusionsMany continuous vertebral bone bridges, especially those that extend to the lumbar spine and low proximal femur BMD, are risk factors for fracture in DISH patients.

A combined experimental and computational study of mechanical properties after balloon kyphoplasty.

Vertebral compression fractures rank among the most frequent injuries to the musculoskeletal system, with more than 1 million fractures per annum worldwide. The past decade has seen a considerable increase in the utilisation of surgical procedures such as balloon kyphoplasty to treat these injuries. While many kyphoplasty studies have examined the risk of damage to adjacent vertebra after treatment, recent case reports have also emerged to indicate the potential for the treated vertebra itself to re-collapse after surgery. The following study presents a combined experimental and computational study of balloon kyphoplasty which aims to establish a methodology capable of evaluating these cases of vertebral re-collapse. Results from both the experimental tests and computational models showed significant increases in strength and stiffness after treatment, by factors ranging from 1.44 to 1.93, respectively. Fatigue tests on treated specimens showed a 37% drop in the rate of stiffness loss compared to the untreated baseline case. Further analysis of the computational models concluded that inhibited PMMA interdigitation at the interface during kyphoplasty could reverse improvements in strength and stiffness that could otherwise be gained by the treatment.

An unusual case of childhood osteoarticular tuberculosis from the Árpádian Age cemetery of Győrszentiván-Révhegyi tag (Győr-Moson-Sopron county, Hungary).

Ancient human remains exhibiting bony changes consistent with osteoarticular tuberculosis (OATB) indicate that the disease has afflicted mankind for millennia. Nonetheless, not many pediatric OATB cases have been published in the paleopathological literature-from Hungary, only three cases have been described up to now. In our paper, we demonstrate a child (S0603) from the Árpádian Age cemetery of Győrszentiván-Révhegyi tag (northwestern Hungary), who represents a unique case of OATB regarding both the pattern and severity of the observed bony changes. During the macromorphological and radiological investigations, the most serious alterations were discovered in the upper thoracic spine-the development of osteolytic lesions led to severe bone loss and consequent collapse and fusion of several adjacent vertebrae. The pathological process terminated in a sharp, rigid angular kyphosis. Disruption of the normal spine curvature resulted in consequent deformation of the whole thoracic wall-it became "rugby-ball-shaped". The overall nature and pattern of the detected alterations, as well as their resemblance to those of described in previously published archaeological and modern cases from the pre-antibiotic era indicate that they are most consistent with OATB. Based on the severity and extent of the lesions, as well as on the evidence of secondary healing, S0603 suffered from TB for a long time prior to death. Besides body deformation, OATB resulted in consequent disability in daily activities, which would have required regular and significant care from others to survive. It implies that in the Árpádian Age community of Győrszentiván-Révhegyi tag, there was a willingness to care for people in need. Detailed archaeological case studies can give us a unique insight into the natural history and different presentations of OATB. Furthermore, they can provide paleopathologists with a stronger basis for diagnosing TB and consequently, with a more sensitive means of assessing TB frequency in past populations.

Pathomechanism and Biomechanics of Degenerative Disc Disease: Features of Healthy and Degenerated Discs.

The human intervertebral disc (IVD) is a complex organ composed of fibrous and cartilaginous connective tissues, and it serves as a boundary between 2 adjacent vertebrae. It provides a limited range of motion in the torso as well as stability during axial compression, rotation, and bending. Adult IVDs have poor innate healing potential due to low vascularity and cellularity. Degenerative disc disease (DDD) generally arises from the disruption of the homeostasis maintained by the structures of the IVD, and genetic and environmental factors can accelerate the progression of the disease. Impaired cell metabolism due to pH alteration and poor nutrition may lead to autophagy and disruption of the homeostasis within the IVD and thus plays a key role in DDD etiology. To develop regenerative therapies for degenerated discs, future studies must aim to restore both anatomical and biomechanical properties of the IVDs. The objective of this review is to give a detailed overview about anatomical, radiological, and biomechanical features of the IVDs as well as discuss the structural and functional changes that occur during the degeneration process.

Warm needling moxibustion plus PKP for vertebral compression fracture due to kidney deficiency and blood stasis: a randomized controlled trial

To explore the efficacy and mechanism of warm needling moxibustion plus percutaneous kyphoplasty (PKP) for osteoporotic vertebral compression fracture (OVCF) due to kidney deficiency and blood stasis. A total of 70 OVCF patients were randomized into a control group and an observation group, with 35 cases in each group. The control group was given PKP treatment, and the observation group was treated with warm needling moxibustion on the basis of the treatment in the control group. The visual analog scale (VAS) and Oswestry disability index (ODI) were scored and the Cobb angle of fractured vertebrae was measured before and after treatment. The re-fracture rate of the adjacent vertebrae was recorded at 1-year follow-up. The serum levels of transforming growth factor (TGF)-β1 and omentin-1 were measured before and after treatment. After treatment, the VAS and ODI scores in both groups decreased (all P<0.05), and all the scores in the observation group were lower than those in the control group (both P<0.05). After treatment, the Cobb angle of fractured vertebrae in both groups decreased (both P<0.05), and the Cobb angle in the observation group was smaller than that in the control group (P<0.05). At 1-year follow-up, the re-fracture rate of the adjacent vertebrae in the observation group was lower than that in the control group (P<0.05). After treatment, the serum levels of TGF-β1 and omentin-1 in both groups increased significantly (all P<0.05), and the serum levels of TGF-β1 and omentin-1 in the observation group were higher than those in the control group (both P<0.05). The treatment of warm needling moxibustion plus PKP can relieve pain, improve dysfunction, promote healing of the injured vertebrae, and reduce the re-fracture rate of the adjacent vertebrae in patients with OVCF due to kidney deficiency and blood stasis, which may be related to the increase of serum TGF-β 1 and omentin-1 levels.

A Finite Element Model of the C1-C4 Human Spine Segment

A three-dimensional FE analysis of four adjacent cervical vertebrae (C1-C4) has been developed. The model is composed of vertebrae and skull but disc ligaments were not considered. The aim of this research is to address the new advancements in the finite element mesh generation of the human cervical spine. The procedure for creating a finite element model based on available biomedical closed volumes obtained from CT scans is introduced.

Finite element assessment of a disc-replacement implant for treating scoliotic deformity

BackgroundBracing and spinal fusion surgery have long been the primary methods for idiopathic scoliosis correction; however, there exist multiple limitations with both techniques. Growth modulation techniques have recently been attempted, but are typically performed across multiple vertebral elements. The aim of this study was to quantify the corrective abilities of a dual-angled, wedge shaped, rigid disc implant designed to correct spinal deformity. MethodsThe 3D spinal geometry of four patients was reconstructed using calibrated radiographs, from which personal finite element models were created. Coronal and sagittal Cobb angles and axial stress distribution were calculated pre- and post- simulation of device implantation at the apical vertebral element. FindingsInsertion of a rigid wedged implant resulted in up to 90.1% coronal correction with kyphotic normalization, and reduced axial stress differential within adjacent vertebrae by up to 83.3%. This correction in axial stress differential was seen to propagate to subjacent vertebrae in both rostral and caudal directions. Insertion of two implants yielded greater correction with respect to all three measures. InterpretationLocal Cobb angle correction, increased kyphotic angle, and a decrease in axial stress differential with adjacent and subjacent vertebral levels demonstrate a potential for deformity correction from within the disc space. The decrease in axial stress differential demonstrates a capacity for growth modulation and reversal of the Heuter-Volkmann principle. Based on qualitative views of spinal shape following device implantation, the wedged implant proved more efficacious in correcting single thoracic curves than double major curves.

The most appropriate titanium mesh cage size for anterior spinal reconstruction after single-level lumbar total en bloc spondylectomy: a finite element analysis and cadaveric validation study

PurposeThere is little information available regarding the cage diameter that can provide the most rigid construct reconstruction after total en bloc spondylectomy (TES). The aim of this study was thus to determine the most appropriate titanium mesh cage diameter for reconstruction after spondylectomy.MethodsA finite element model of the single level lumbar TES was created. Six models of titanium mesh cage with diameters of 1/3, 1/2, 2/3, 3/4, 4/5 of the caudad adjacent vertebra, and 1/1 of the cephalad vertebra were tested for construct stiffness. The peak von Mises stress (MPa) at the failure point and the site of failure were measured as outcomes. A cadaveric validation study also conducted to validate the finite element model.ResultsFor axial loading, the maximum stress points were at the titanium mesh cage, with maximum stress of 44,598 MPa, 23,505 MPa, 23,778 MPa, and 16,598 MPa, 10,172 MPa, 10,805 MPa in the 1/3, 1/2, 2/3, 3/4, 4/5, and 1/1 diameter model, respectively. For torsional load, the maximum stress point in each of the cages was identified at the rod area of the spondylectomy site, with maximum stress of 390.9 MPa (failed at 4459 cycles), 141.35 MPa, 70.098 MPa, and 88.972 MPa, 42.249 MPa, 15.827 MPa, respectively. A cadaveric validation study results were coincided with the finite element model results.ConclusionThe most appropriate mesh cage diameter for reconstruction is 1/1 the diameter of the lower endplate of the adjacent cephalad vertebra, due to its ability to withstand both axial and torsional stress. According to the difficulty of large size cage insertion, a cage diameter of more than half of the upper endplate of the caudad vertebrae is acceptable in term of withstand stress. A cage diameter of 1/3 is unacceptable for reconstruction after total en bloc spondylectomy.

Experimental Investigation of an Influence of Coupled Compressive Loading on Porcine Spine Specimens

The human spine shortens approximately by 1% of its height during the daily activities and returns to its primary height during the night rest. Cyclic loading is important in order to ensure diffusion and convention of the nutrients and metabolites within the intervertebral discs. On the other hand, cyclic loading could lead to the damage of the intervertebral discs and the vertebra bodies if the magnitude and frequency of the loads applied to the spine exceed the allowable limits. As most of the in vitro studies that investigate the influence of cyclic loading deal with functional spinal units consisting of single intervertebral disc the purpose of this study is to investigate an influence of cyclic compression and flexion on the structural integrity and geometrical parameters of the spinal specimens consisting of more than one intervertebral disc. Two specimens consisting of four adjacent vertebrae and three intervertebral discs were scanned by using computed tomography then loaded with combined cyclic compression and flexion and then scanned for the second time in order to capture the current condition of the specimens. Obtained images were used to evaluate the changes of structural integrity and geometrical parameters of the discs. A significant decrease of the specimen height was observed during loading, mainly due to the loss of the fluid content within intervertebral discs. In total, the difference of the height of the two specimens immediately after the loading was 1.577 mm. No obvious damage to the specimens was observed when comparing images before and after the loading. A statistically significant differences between the height of the intervertebral discs before and after loading in both the first specimen (p = 0.0224) and the second specimen (p = 0.0155) were calculated with the lowest disc of both specimens decreasing the most and obviously losing the highest water content. The cross-sectional area of the lowest disc in both specimens also decreased the most. This once again confirms that lower part of the spine such as intervertebral discs L4-L5 and L5-S1 are the least prone to the injuries and degeneration due to disturbed nutrition and loss of water content.

Spondylodiscitis and epidural abscesses

Klinisches/methodisches ProblemDie Spondylodiszitis ist eine Entzündung der intervertebralen Bandscheibe, die beim Erwachsenen aufgrund der Vaskularisation in der Regel mit einer Spondylitis der angrenzenden Wirbelkörper einhergeht und klinisch häufig nur unspezifische Symptome wie Rücken- oder Nackenschmerzen zeigt. Sie kann erregerassoziiert von verschiedenen Pathogenen, v. a. Bakterien, verursacht werden. Dabei können ein oder mehrere Bewegungssegmente betroffen sein. Die Infektion kann epidurale Abszedierungen verursachen und sich auch auf umliegende Kompartimente ausbreiten. Die Radiologie, und hier insbesondere die Magnetresonanztomographie (MRT), spielt eine wichtige Rolle bei der Primärdiagnostik und im Rahmen von Verlaufsbeurteilungen zur Überprüfung des Therapieansprechens. Die Therapie beruht auf konservativen (Antibiotika) und invasiven Ansätzen, einschließlich einer Operation. Die interventionelle Punktion und Drainage ist v. a. in frühen Stadien der Abszessbildung eine vielversprechende Alternative.Radiologische StandardverfahrenMagnetresonanztomographie (MRT), Computertomographie (CT), nuklearmedizinische Verfahren, konventionelles Röntgen.LeistungsfähigkeitDie MRT hat den höchsten Stellenwert. CT und nuklearmedizinische Verfahren können ergänzend und im Fall bestehender Kontraindikationen zur MRT eingesetzt werden.SchlussfolgerungBei adäquater Diagnostik und Therapie hat die Spondylodiszitis eine gute Prognose. Neben der gezielten bzw. kalkulierten medikamentösen Therapie steht beim epiduralen Abszess die invasive Therapie im Vordergrund. Die interventionell-radiologische Punktion und Drainage (auch zur Keimidentifikation für die gezielte Antibiotikatherapie) können frühzeitig eine schonende Alternative zur chirurgischen Sanierung darstellen.

The Spinebot—A Robotic Device to Intraoperatively Quantify Spinal Stiffness

Abstract Degenerative spine problems and spinal deformities have high socio-economic impacts. Current surgical treatment is based on bony fusion that can reduce mobility and function. Precise descriptions of the biomechanics of normal, deformed, and degenerated spinal segments under in vivo conditions are needed to develop new approaches that preserve spine function. This study developed a system that intraoperatively measures the three-dimensional segmental stiffness of patient's spine. SpineBot, a parallel kinematic robot, was developed to transmit loads to adjacent vertebrae. A force/torque load cell mounted on the SpineBot measured the moment applied to the spinal segment and calculated segmental stiffnesses. The accuracy of SpineBot was characterized ex vivo by comparing its stiffness measurement of five ovine specimens to measurements obtained with a reference spinal testing system. The SpineBot can apply torques up to 10 N·m along all anatomical axes with a total range of motion of about 11.5 deg ± 0.5 deg in lateral bending, 4.5 deg ± 0.3 deg in flexion/extension, and 2.6 deg ± 0.5 deg in axial rotation. SpineBot's measurements are noisier than the reference system, but the correlation between SpineBot and reference measurements was high (R2 &amp;gt; 0.8). In conclusion, SpineBot's accuracy is comparable to that of current reference systems but can take intraoperative measurements. SpineBot can improve our understanding of spinal biomechanics in patients who have the pathology of interest, and take these measurements in the natural physiological environment, giving us information essential to developing new “nonfusion” products.

LPAQR-Net: Efficient Vertebra Segmentation From Biplanar Whole-Spine Radiographs.

Vertebra segmentation from biplanar whole-spine radiographs is highly demanded in the quantitative assessment of scoliosis and the resultant sagittal deformities. However, automatic vertebra segmentation from the radiographs is extremely challenging due to the low contrast, blended boundaries, and superimposition of many layers, especially in the sagittal plane. To alleviate these problems, we propose a lightweight pyramid attention quick refinement network (LPAQR-Net) for efficient and accurate vertebra segmentation. The LPAQR-Net consists of three components: (1) a lightweight backbone network (LB-Net) to prune network parameters and memory footprints to strike an optimal balance between speed and accuracy, (2) a series of global attention refinement (GAR) modules to selectively reuse low-level features to facilitate the feature refinement, and (3) an attention-based atrous spatial pyramid pooling (A-ASPP) module to extract weighted pyramid contexts to improve the segmentation of blurred vertebrae. Moreover, the multi-class training strategy is employed to alleviate the over-segmentation of adjacent vertebrae. Evaluation results on both frontal and lateral radiographs of 332 AIS patients show our method achieves accurate vertebra segmentation with significant reductions in inference time and computational demands compared to the state-of-the-art. Meanwhile, results on the public AASCE2019 dataset also demonstrate the good generalization ability of our model. It is the first attempt to explore the lightweight network for vertebra segmentation from biplanar whole-spine radiographs. It simulates radiologists gathering nearby contexts for accurate and robust vertebra boundary inference. The method can provide efficient and accurate vertebra segmentation for clinicians to perform a fast and reproducible spinal deformity evaluation.

Human Thoracolumbar Spine Tolerance to Injury and Mechanisms From Caudo-Cephalad Loading: A Parametric Modeling Study.

The aims of this investigation were to delineate the internal biomechanics of the spine under vertical impact vector and assess the probability of injury. Male and female whole-body human finite element models were used. The restrained occupants were positioned on the seat, and caudo-cephalad impacts were applied to the base. Different acceleration-time profiles (50-200 ms pulse durations, 11-46 g peak accelerations) were used as inputs in both models. The resulting stress-strain profiles in the cortical and cancellous bones were evaluated at different vertebral levels. Using the peak transmitted forces at the thoracolumbar disc level as the response variable, the probability of injury for the male spine was obtained from experimental risk curves for the various pulses. Results showed that the shorter pulse durations and rise times impart greater loading on the thoracolumbar spine. The analysis of von Mises stress and strain distributions showed that the compression-related fractures are multifaceted with contributions from both the cortical and cancellous bony components of the body. Profiles are provided in the paper. The intervertebral disc may be involved in the fracture mechanism, because it acts as a medium of load transfer between adjacent vertebrae. Injury risks for the shortest pulse was 63%, and for the widest pulse it was close to zero, and injury probabilities for other pulses are given. The present modeling study provides insights into the mechanisms of internal load transfer and describes injury risk levels from caudal to cephalad impacts.

A Retrospective Analysis in 1347 Patients Undergoing Cement Augmentation for Osteoporotic Vertebral Compression Fracture: Is the Sandwich Vertebra at a Higher Risk of Further Fracture?

Multiple percutaneous vertebral cement augmentation may create sandwich vertebrae. Whether the sandwich vertebra is at higher risk of further fracture remains unknown. To compare the incidence of further fractures of sandwich vertebrae and adjacent vertebrae and to identify potential risk factors for sandwich vertebral fractures. Patients who underwent cement augmentation for osteoporotic vertebral compression fractures (OVCFs) in a single medical center between January 2012 and December 2015 were included. A sandwich vertebra was defined as an intact vertebra located between 2 previously cemented vertebrae. Demographic data and imaging findings were recorded. All patients were followed up for at least 24 mo postoperatively. During follow-up period, if the patient reported new-onset back pain with corresponding imaging findings, a diagnosis of sandwich vertebral fracture was made. Among the 1347 patients who underwent vertebroplasty/kyphoplasty for OVCFs, 127 patients with 128 fracture levels met the criteria for sandwich vertebrae (females/males 100/27, mean age 77.8±7.7yr old). The fracture location was most common in the thoraco-lumbar junction (T10-L2), 68.5% (87/127). The incidence of sandwich vertebral fracture was 21.3%, whereas the incidence of adjacent level fracture of those with no sandwich vertebra was 16.4% (196/1194), P=.1879. The incidence of sandwich vertebral fracture is not higher than that at the adjacent levels. The factor associated with further sandwich vertebral fracture was male gender. Once sandwich vertebral fracture occurred, patients may seek more surgical intervention than those with only adjacent fractures.

Algoritm for surgical method of treatment at spine tumors

The main goal of the primary and metastatic spinal tumors treatment are local control, preservation of weight bearing and protective function of the spine with improvement patients quality of life. Objective. To develop mathematical algorithm for selection of surgical treatment volume in spinal tumor cases. Methods. Spinal instability neoplastic score supplemented with additional signs such as ASIA scale, tumor type, epidural spinal cord compression scale by Bilsky, local kyphosis, adjacent vertebras lesions was used for the model developing. Point system that takes 9 signs has been tested in 237 metastatic spinal tumor patients. Cluster analysis for the decision tree development was applied. Results. It has been confirmed the hypothesis about decreasing surgical volume with higher SINS score. But, it was not defined which boundary indicator to define specific volume of the surgery is precise. Two patients clusters were defined, that have differences in the surgical volume, degree of tumor lesion, epidural compression and local kyphosis, neurological symptoms. Cluster I included 115 patients with higher score (severe condition, higher volume of the surgical intervention) in comparison with 122 patients from the cluster II. Decision tree for the surgical volume selection in spinal tumor patients has been developed. Conclusions. The most important signes that affect the choice of the surgical volume selection are: neurological symptoms, type of vertebra lesion, spinal stenosis and type of the surgery (radical vs palliative). Application of the deve­loped decision tree in the clinical practise gives the opportunity to select appropriate volume of the surgical intervention in spinal tumor patient with the high significance level that provides satisfactory treatment outcome.

Three dimensional finite element analysis of optimal distribution model of fillers in vertebroplasty

To establish a three-dimensional finite element model of osteoporosis and to study the stiffness recovery of injured vertebrae and stress analysis of adjacent vertebrae after percutaneous vertebroplasty under different perfusion and distribution conditions by simulating fluid flow into the vertebral body. A male healthy volunteer was selected. CT scans were performed from T11 to L2. Mimics 15.0 and ABAQUS 6.11 software were used to extract CT images. The vertebral model of osteoporotic fracture was established. The flow physical field and conduction and diffusion physical field were coupled to simulate the process and parts of the injection of bone cement into the vertebral fracture model. The amount of bone cement injected into the vertebral fracture model was 2 ml, 4 ml, 6 ml respectively. The diffusion range of bone cement was simulated on the image, and the post injection model of bone cement was obtained. Vertical downward, forward and backward pressure of 300 N were applied on the surface of the model to simulate vertebral movement. The stress changes of upper and lower vertebrae and diseased vertebrae under different conditions were calculated. (1) The VonMises stress of T12 inferior endplate was the largest in the three states before and after fracture.(2) The VonMises stress of the intervertebral disc and each endplate after fracture was significantly higher than before fracture. When percutaneous vertebroplasty was applied, as the amount of bone cement injection increases, the VonMises stress of the adjacent vertebral endplates increases. In the diseased vertebrae, as the amount of bone cement increases, the VonMises stress of the vertebral body endplate showed a downward trend. Reliable biomechanical model of lumbar vertebral fracture can be established by using CT scanning data through software simulation. Vertebral fracture and vertebroplasty will cause biomechanical changes of adjacent vertebral bodies. With the increase of bone cement injection, the influence of biomechanical changes will increase significantly. Neighbouring vertebral fractures are more likely. For this experiment, percutaneous vertebroplasty has a suitable amount of cement injection of 4 ml.