Posterior Elements Research Articles

Video-Assisted Thoracoscopic Lateral Interbody Fusion for Symptomatic Pseudarthrosis in Neurofibromatosis 1-Associated Spinal Deformity

The treatment of symptomatic pseudarthrosis via posterior-only approaches in the setting of neurofibromatosis 1 (NF1) is challenging due to dural ectasias, resulting in erosion of the posterior elements. The purpose of this report is to illustrate a minimally invasive method for performing anterior thoracic fusion for pseudarthrosis in a patient with NF1-associated scoliosis and dysplastic posterior elements. To the best of our knowledge, this is the first documented case of using video-assisted thoracoscopic lateral interbody fusion to treat pseudarthrosis for NF1-associated spinal deformity. The patient underwent video-assisted thoracoscopic anterior spinal fusion via a direct lateral interbody approach with interbody cage placement at T10-T11 and T11-T12, followed by revision of his posterior spinal fusion and instrumentation. The patient had an uneventful postoperative course. At 6 months of follow-up, the patient had complete resolution of his preoperative symptoms and had returned to full-time work with no complaints. At 3 years postoperatively, the patient reported being satisfied with the operation and had continued to work full-time without restrictions. To the best of our knowledge, this is the first report of pseudarthrosis in the setting of NF1-associated scoliosis treated via minimally invasive anterior thoracic fusion facilitated by video-assisted thoracoscopic surgery. This is a powerful technique that allows for safe access for anterior thoracic fusion in the setting of dysplastic posterior anatomy and poor posterior bone stock.

Scoliosis in a patient with nemaline myopathy: a case report and narrative review

Introduction: Nemaline myopathy, described in 1950, is a rare syndrome, and among the possible alterations, scoliosis is a frequent alteration. This article describes the case of a 13-year-old patient with nemaline myopathy and scoliosis treated surgically. During the procedure, several unexpected surgical difficulties were encountered, such as fusion of posterior elements, difficulty in passing screws and liquor leaked out. Therefore, more studies are necessary and the presence of an experimental operation to help with surgical complications are prudent.

Prophylactic Radiotherapy Of MInimally Symptomatic Spinal Disease (PROMISSeD): study protocol for a randomized controlled trial

BackgroundEarly palliative/pre-emptive intervention improves clinical outcomes and quality of life for patients with metastatic cancer. A previous signal-seeking randomized controlled trial (RCT) demonstrated that early upfront radiotherapy to asymptomatic or minimally symptomatic high-risk osseous metastases led to reduction in skeletal-related events (SREs), a benefit driven primarily by subgroup of high-risk spine metastasis. The current RCT aims to determine whether early palliative/pre-emptive radiotherapy in patients with high-risk, asymptomatic or minimally symptomatic spine metastases will lead to fewer SREs within 1 year.MethodsThis is a single-center, parallel-arm, in-progress RCT in adults (≥ 18 years) with ECOG performance status 0–2 and asymptomatic or minimally symptomatic (not requiring opioids) high-risk spine metastases from histologically confirmed solid tumor malignancies with > 5 sites of metastatic disease on cross-sectional imaging. High-risk spine metastases are defined by the following: (a) bulkiest disease sites ≥ 2 cm; (b) junctional disease (occiput to C2, C7-T1, T12-L2, L5-S1); (c) posterior element involvement; or (d) vertebral body compression deformity > 50%. Patients are randomized 1:1 to receive either standard-of-care systemic therapy (arm 1) or upfront, early radiotherapy to ≤ 5 high-risk spine lesions plus standard-of-care systemic therapy (arm 2), in the form of 20–30 Gy of radiation in 2–10 fractions. The primary endpoint is SRE, a composite outcome including spinal fracture, spinal cord compression, need for palliative radiotherapy, interventional procedures, or spinal surgery. Secondary endpoints include (1) surrogates of health care cost, including the number and duration of SRE-related hospitalizations; (2) overall survival; (3) pain-free survival; and (4) quality of life. Study instruments will be captured pre-treatment, at baseline, during treatment, and at 1, 3, 6, 12, and 24 months post-treatment. The trial aims to accrue 74 patients over 2 years to achieve > 80% power in detecting difference using two-sample proportion test with alpha < 0.05.DiscussionThe results of this RCT will demonstrate the value, if any, of early radiotherapy for high-risk spine metastases. The trial has received IRB approval, funding, and prospective registration (NCT05534321) and has been open to accrual since August 19, 2022. If positive, the trial will expand the scope and utility of spine radiotherapy.Trial registrationClinicalTrials.Gov NCT05534321. Registered September 9, 2022.Trial statusVersion 2.0 of the protocol (2021-KOT-002), revised last on September 2, 2022, was approved by the WCG institutional review board (Study Number 1337188, IRB tracking number 20223735). The trial was first posted on ClinicalTrials.Gov on September 9, 2022 (NCT05534321). Patient enrollment commenced on August 19, 2022, and is expected to be completed in 2 years, likely by August 2024.

Finite element analysis of the cervical spine: dynamic characteristics and material property sensitivity study

The study aimed to investigate the dynamic characteristics of the cervical spine and determine the effect of the material properties of the cervical spinal components on it. A finite element model of the head-cervical spine was developed based on CT scan data, and the first six orders of modes (e.g. flexion-extension, lateral bending, and vertical, etc.) were verified by experimental and simulation studies. The material sensitivity study was conducted by varying elasticity modulus of cervical hard tissues (cortical bone, cancellous bone, endplates, and posterior elements) and soft tissues (intervertebral disc and ligaments). The results showed that increasing the elastic modulus of ligaments by 4 times increased the natural frequency by 77%, while increasing that of cancellous bone by 4 times only increased the natural frequency by 6%. In the axial mode, the cervical spine had not only axial deformation but also anterior-posterior deformation, with the largest deformation located at the intervertebral disc C6-C7. Decreasing the elastic modulus of a component in soft tissues by 80% increased modal displacement by up to 62%. The material properties of the intervertebral discs and ligaments had opposite effects on the modal displacement and deformation of the cervical spine. Low cervical discs were more susceptible to injury in a vertical vibration environment. Cervical spine dynamics were more sensitive to soft tissue material properties than to hard tissue material properties. Disc degeneration could reduce the range of vibratory motion of the cervical spine, thereby reducing the ability of the cervical spine to cushion head impacts.

Proximal junctional kyphosis in Lenke 5C adolescent idiopathic scoliosis after selective posterior thoracolumbar/lumbar fusion: risk factors and predictive index

BackgroundAlthough several studies have reported that selective posterior thoracolumbar/lumbar (TL/L) fusion can yield satisfactory results in Lenke 5C adolescent idiopathic scoliosis (AIS), the proximal junctional kyphosis (PJK) is still a common complication that occurs after surgery. The purpose of this study is to analyse the risk factors for postoperative proximal junctional kyphosis in Lenke 5C patients who underwent selective posterior TL/L fusion and explore whether PJK can be predicted.MethodsA total of 83 AIS patients with Lenke 5C curves who met the inclusion criteria were analysed. All patients were divided into two groups based on the occurrence of postoperative PJK. Univariate and multivariate analyses were used to identify independent factors significantly associated with PJK, and an PJK index was proposed and verified.ResultsPJK was observed in 27 of 83 (32.5%) patients in the study. Preoperative thoracic kyphosis (TK) and the immediate postoperative proximal junctional angle (PJA) were the primary factors identified by the binary logistic regression analysis. The PJK index was defined as 1.1× preoperative TK + 2.3× immediate postoperative PJA. The receiver operating characteristics curve indicated that the occurrence rate of PJK was 85% and non-occurrence rate was 82% when the PJK index was greater than 42.ConclusionLarge preoperative TK and a large immediate postoperative PJA play important roles in the development of PJK in Lenke 5C patients treated with selective posterior thoracolumbar/lumbar fusion. The PJK index can be used to predict the occurrence of PJK with high accuracy. To prevent the occurrence of PJK, we should pay attention to the TLK, and preserving more posterior proximal intervertebral elements at the upper instrumented vertebral level would be an important part of corrective surgery; however, moderate correction of the lumbar curve is recommended.

Posterior Column Reconstruction of the Lumbar Spine Using En Bloc Resected Vertebral Arch in Spinal Tumor and Deformity Surgeries.

In high-grade spinal osteotomy involving large anterior column resection, restoration of the structural integrity of the posterior column at the osteotomy site can reduce postoperative instrumentation failure (IF). This study aimed to describe our technique of posterior strut bone grafting using an en bloc resected vertebral arch, which is useful for posterior column reconstruction after high-grade osteotomies during surgeries for spinal tumor and deformity in the lower lumbar spine. Using a posterior approach, en bloc resection of the targeted vertebral arch was performed in accordance with the surgical technique for total en bloc spondylectomy (TES). The posterior elements in the upper and lower adjacent vertebrae were separated by a significant space after vertebral body resection followed by cage insertion in TES or anterior column osteotomy followed by correction in deformity surgery. To create a new posterior column, the en bloc resected vertebral arch was placed at 90° rotation to bridge the upper and lower vertebral arches. Using this technique, an abundant amount of bone chips made from the resected vertebral elements were placed over the en bloc resected posterior arch as an additional bone graft. The technique was used in three patients who underwent TES for spinal tumors and in one patient who underwent grade 4 osteotomy for adult spinal deformity in the lower lumbar spine. One year after surgery, computed tomography showed that the structural integrity of bony fusion was successfully achieved between the en bloc resected arch and the posterior elements of the adjacent vertebrae in all patients and showed no postoperative IFs. This bone graft technique created new continuity of the posterior column after high-grade osteotomies in the lower lumbar spine. Bone fusion was achieved in the posterior elements to prevent IF after surgery.

Aneurysmal Bone Cyst of the Distal Ulna in an Elderly Lady

Introduction: Aneurysmal bone cyst (ABC) is a rare, benign, cystic, hemorrhagic expansile osteolytic lesion of unknown etiology resembling multiple intraosseous blood-filled spaces mostly seen in the first two decades of life. It accounts for &lt;1% of all bone tumors and the usual sites are the metaphyses of the proximal and distal femur, proximal tibia, and posterior elements of the spine. Affection of other sites is unusual. Case: A 55-year-old female with a 5-month history of pain and swelling of distal ulna. She was operated on with curettage, bone grafting, and plating. At 1-year follow-up, she regained complete movements without any recurrence. Conclusion: In this article, we present a case of a primary ABC of distal ulna in an unusual age group of 55 years in a female. The clinical presentation, diagnosis, surgical management, and clinical outcome at 1 year are described. Keywords: Aneurysmal bone cyst, elderly, distal ulna.

Distinct characteristics and progression patterns of facet joint structural lesions in radiographic axial spondyloarthritis.

Both vertebral bodies and posterior elements of the vertebrae (facet joints, FJ) can engage in bone formation in radiographic axial spondyloarthritis (r-axSpA). However, little is known about the specific structural lesions and progression patterns of FJs in r-axSpA. To identify specific lesions related to r-axSpA and to investigate the distinct progression patterns by comparing the FJ changes of r-axSpA with that of diffuse idiopathic skeletal hyperostosis (DISH), osteoarthritis (OA), and control group (CG). Single-center, retrospective study. Longitudinal imaging data were retrieved and collected. Age- and sex-matched patients with complete thoracic and lumbar spine computed tomography (CT) data were included and their bilateral FJs were assessed. FJ changes were divided into erosions, ankylosis, joint-space narrowing, osteophytes, subchondral sclerosis, subchondral cysts, and vacuum phenomena. Average progressed year was defined as "number of changed vertebrae × interval years"/number of changed vertebrae. In all, 50 patients in each group were included. Subchondral cysts and vacuum phenomena were not observed. Bilateral FJ ankylosis (FJA)/erosions in the thoracic and lumbar spine, and unilateral ankylosis/erosions in T1-4, T9-12 were significantly more common in r-axSpA. Joint-space narrowing/osteophytes/subchondral sclerosis were significantly more common in DISH and OA. FJ lesions progressed in 56.34% of vertebrae of r-axSpA. The most common pattern was "FJ normal advanced to ankylosis" (17.54%) which required 2.63 years. It was followed by "erosions advanced to ankylosis" (12.3%) which took 2.05 years, and by "normal FJ advanced to erosions" (11.04%) which took 2.29 years, respectively. Degenerative changes could also progress to FJ erosions/ankylosis (24.83%). The majority pattern in DISH/OA was "FJ changes advanced to subchondral sclerosis/osteophytes/joint-space narrowing." Bilateral FJA/erosions are r-axSpA-specific lesions. The specific progression pattern for r-axSpA was "FJ changes advanced to ankylosis/erosions." Repeated CT examination in intervals of at least 2 years will be more appropriate for monitoring FJ progression.

Standalone Percutaneous Vertebroplasty for Hyperextension Injuries of the Ankylosed Thoracolumbar Spinal Kyphosis.

Hyperextension injuries of the ankylosed thoracolumbar spine, particularly those with preexisting kyphotic deformity, present significant therapeutic challenges. The authors viewed that such injuries without displacement or fractures of the posterior elements are reasonable candidates for standalone percutaneous vertebroplasty (PVP). In such cases, the posterior tension band is spared; thus, fractures are unstable not in the lateral direction, which would lead to the translation of the fracture, but in the vertical direction. Such vertical instability of the fracture can be stabilized if the open mouth-type vertebral cleft is adequately filled with a sufficiently large amount of polymethylmethacrylate (PMMA) cement. Our three patients receiving standalone PVP received injections of 12 mL, 16.5 mL, and 18 mL of PMMA cement. This minimally invasive surgical procedure achieved both short-term (immediate pain relief and mobilization) and long-term (fracture healing) goals.

Epitheloid Haemangioma of Spine - A Rare Case Report and Review of Literature

Introduction: Epitheloid hemangioma (EH) of spine is a rare vascular disease. Haemangiomas are tumours typically composed of thin walled blood vessels, of which EH is an infrequent variation. The exact incidence of EH is not known. EH, though is considered to be benign disease it can be locally aggressive. EH most commonly affects the integumentary system. IT most commonly involves liver, lungs and bones. Here we report a 25 years old male with complete work up for EH including clinical data, MRI spine, surgical, histopathological information and adjuvant radiation therapy following surgical management. In addition to the case report, we reviewed literature on EH of bones. Case Report: A 25 years old male came to our emergency department with complaints of severe lower back pain. He also complained of difficulty in walking for the past 3 months. MRI Lumbosacral (LS) with whole spine screening was done 1 month back and it showed Multifocal vertebral lesions involving D4, D5, D6 vertebra predominantly in posterior elements, expansion of the transverse processes and involvement of costochondral junction, left 5th rib with extensive soft tissue component indenting on the pleura. He was seen by Neurosurgery team at our hospital and was planned for surgical decompression and stabilisation of D4-D6 vertebrae. He underwent D3 to D6 laminectomy and stabilization under general anaesthesia. Final histopathology along with IHC correlation was suggestive of Epitheloid Hemangioma. Case was discussed in our hospital multidisciplinary tumor board and was planned for adjuvant radiotherapy (RT). Then he received adjuvant radiotherapy total dose (TD) 45 Gray (Gy) to D3-D6 region. Post treatment 6 months, his power is improved and is near normal. Conclusion: To summarize our case appears as a typical features of EH like young male patient, lytic lesions with sclerotic rim, IHC confirmation

Spinal Involvement in Patients with Chronic Non-Bacterial Osteomyelitis (CNO): An Analysis of Distinctive Imaging Features

Spinal involvement by chronic non-bacterial osteomyelitis (CNO) has been increasingly reported in recent years, often being presented as a diagnostic dilemma requiring differential diagnosis with bacterial spondylodiscitis and/or neoplasia. This study was aimed at identifying the imaging features of CNO facilitating its differentiation from other spinal diseases. Two radiologists assessed the imaging studies of 45 patients (16 male and 29 female, aged from 6 to 75 years, 15 children) with CNO collected from 5 referential centers. Spinal lesions were found in 17 patients (2 children and 15 adults), most often in the thoracic spine. In children, the lesions involved short segments with a destruction of vertebral bodies. In adults, the main findings were prominent bone marrow edema and osteosclerosis, endplate irregularities, and ankylosing lesions extending over long segments; paraspinal inflammation was mild and abscesses were not observed. In both children and adults, the involvement of posterior elements (costovertebral and facet joints) emerged as an important discriminator between CNO and neoplasia/other inflammatory conditions. In conclusion, a careful inspection of imaging studies may help to reduce the number of biopsies performed in the diagnostic process of CNO.

Tubercolosi vertebrale atipica: un caso clinico e revisione della letteratura

Background - Rates of Extrapulmonary Tuberculosis (TB) are higher in paediatric patients, especially in those from endemic areas. Bone TB is mostly located in the spine and in children may cause rapid bone destruction with severe deformity and neurological deficits. Case report - The paper reports the case of a 14-year-old male patient from Pakistan presenting with neurological symptoms and neuroradiological features suspicious for malignant tumour. After surgical removal of the mass, PCR test showed spinal TB. Tuberculin skin test (TST) and Interferon-Gamma Release Assays (IGRA) resulted negative. Discussion - False negative IGRA and TST test results can occur due to several factors, including immunodeficiency disorders. Some cases of spinal TB do not have typical radiological features, causing diagnostic delays or mistakes. Non-typical spinal TB features include: (1) involvement of the posterior elements of the spinal column; (2) skip lesions; (3) non-osseous TB involving spinal cord, cauda equina, and/or meninges. Conclusion - The differential diagnosis between spinal TB and malignancy might be challenging. Consequently, considering TB in children with neurological symptoms and/or vertebral neoformation, especially in patients coming from endemic areas, is recommended. TB diagnosis should not be excluded in case of non-typical radiological features, negative TST and IGRA or history of anti-TB vaccination. This approach should facilitate a timely diagnosis for appropriate treatment, avoiding neurological sequalae and delayed deformities.

Intraoral low-temperature degradation of monolithic zirconia dental prostheses: 5-year results of a prospective clinical study with ex vivo monitoring

ObjectivesTo investigate the 5-year intraoral evolution and kinetics of low-temperature degradation (LTD) of second-generation monolithic prostheses made of 3% molar yttrium-doped tetragonal zirconia polycrystal (3Y-TZP) and the influence of masticatory mechanical stresses and glaze layer on this evolution. MethodsA total of 101 posterior tooth elements were included in this prospective clinical study, which comprised ex vivo LTD monitoring (at baseline, 6 months, 1 year, 2 years, 3 years, and 5 years) using Raman spectroscopy (n = 2640 monoclinic phase measurement points per evaluation time) and scanning electron microscopy (SEM). Four types of areas (1–2 mm2 surface, six on molars, and four on premolars) were analysed on each element surface: occlusal, axial, glazed, or unglazed. Raman mapping, high-resolution SEM, and focused ion beam-SEM were performed on selected samples. ResultsThe dental prostheses developed a tetragonal-to-monoclinic transformation at the extreme surface of the material after six months in a buccal environment, and this process increased significantly over time. Over the five years of monitoring, the transformation developed nonuniformly with the presence of localised clusters of monoclinic grains. Tribological stresses generate grain pull-out from these clusters, which may raise questions regarding the release of 3Y-TZP nanoparticles into the body. The prosthesis fracture rate was 4.5% after 5 years. SignificanceLTD developed in vivo on the surfaces of 3Y-TZP dental prostheses and progressed slowly but significantly over time, up to 5 years investigation. However, the effects of aging on the failure rate recorded and of zirconia nanoparticles released into the body require further investigation.

New Bone Formation in Axial Spondyloarthritis: A Review.

Background Axial spondyloarthritis (axSpA) is a chronic inflammatory disease primarily affecting the sacroiliac joints (SIJs) and the spine. Imaging plays a crucial role in the diagnosis of axSpA, with magnetic resonance imaging (MRI) and radiography being the primary modalities used in clinical practice. New bone formation occurs in both the spine (non-bridging and bridging syndesmophytes, transdiscal ankylosis, and ankylosis of small joints and posterior elements) and the SIJs (backfill and ankylosis). New bone formation indicates advanced axSpA. Method This review explores the role of imaging in the diagnosis and monitoring of axSpA, focusing on the significance of new bone formation, and provides an overview of the characteristic imaging findings of new bone formation in axSpA in each imaging modality. Conclusion Imaging methods, such as X-ray, MRI, and CT, have different diagnostic accuracies for detecting structural lesions and new bone formation. Each modality has its strengths and weaknesses, and the choice depends on the specific clinical context. Imaging is crucial for the diagnosis and monitoring of axSpA, particularly for the detection of new bone formation. Different imaging techniques provide valuable information about disease progression and treatment response. Understanding the significance of new bone formation and its detection using imaging modalities is essential for the accurate diagnosis and effective management of patients with axSpA. Key Points:

Quantitative Tension on the Abdominal Wall in Posterior Components Separation With Transversus Abdominis Release

Posterior components separation (PCS) is a commonly used myofascial release technique in ventral hernia repairs. The contribution of each release with anterior and posterior fascial advancement has not yet been characterized in patients with ventral hernias. To quantitatively assess the changes in tension on the anterior and posterior fascial elements of the abdominal wall during PCS to inform surgeons regarding the technical contribution of each step with those changes, which may help to guide intraoperative decision-making. This case series enrolled patients from December 2, 2021, to August 2, 2022, and was conducted at the Cleveland Clinic Center for Abdominal Core Health. The participants included adult patients with European Hernia Society classification M1 to M5 ventral hernias undergoing abdominal wall reconstruction with PCS. A proprietary, sterilizable tensiometer measured the force needed to bring the fascial edge of the abdominal wall to the midline after each step of a PCS (retrorectus dissection, division of the posterior lamella of the internal oblique aponeurosis, and transversus abdominis muscle release [TAR]). The primary study outcome was the percentage change in tension on the anterior and posterior fascia associated with each step of PCS with TAR. The study included 100 patients (median [IQR] age, 60 [54-68] years; 52 [52%] male). The median (IQR) hernia width was 13.0 (10.0-15.2) cm. After complete PCS, the mean (SD) percentage changes in tension on the anterior and posterior fascia were -53.27% (0.53%) and -98.47% (0.08%), respectively. Of the total change in anterior fascial tension, retrorectus dissection was associated with a mean (SD) percentage change of -82.56% (0.68%), incision of the posterior lamella of the internal oblique with a change of -17.67% (0.41%), and TAR with no change. Of the total change in posterior fascial tension, retrorectus dissection was associated with a mean (SD) percentage change of -3.04% (2.42%), incision of the posterior lamella of the internal oblique with a change of -58.78% (0.39%), and TAR with a change of -38.17% (0.39%). In this case series, retrorectus dissection but not TAR was associated with reduced tension on the anterior fascia, suggesting that it should be performed if anterior fascial advancement is needed. Dividing the posterior lamella of the internal oblique aponeurosis and TAR was associated with reduced tension on the posterior fascia, suggesting that it should be performed for posterior fascial advancement.

Imaging the Posterior Elements of the Spine.

The posterior elements of the spine consist of the pedicles, laminae, facets (articular processes), transverse processes, and the spinous process. They are essential for spinal stability, protecting the spinal cord and nerve roots, and enabling movement of the spine. Pathologies affecting the posterior elements can cause significant pain and disability. Imaging techniques, such as conventional radiography, computed tomography, and magnetic resonance imaging, are crucial for the diagnosis and evaluation of pathology, enabling accurate localization, characterization, and staging of the disease.

Stereotactic Body Radiotherapy for Posterior Element Only Spinal Metastases: Outcomes and Validation of Recommended Clinical Target Volume Delineation Practice

Spine stereotactic body radiotherapy (SBRT) results in improved local control and pain response compared to conventional external beam radiotherapy. Consensus stipulates MRI-based delineation of the clinical target volume (CTV) is critical and is based on spine segment sector involvement. The applicability of these contouring guidelines to metastases confined to the posterior elements is unknown. The purpose of this study was to determine the patterns of failure, as well as the safety of treating posterior element metastases when the vertebral body was intentionally excluded from the CTV. A retrospective review of a prospectively maintained database of 605 patients and 1412 spine segments treated with spine SBRT was performed. Only treated segments involving the posterior elements alone were included for the analyses. The primary outcome was local failure, as per SPINO recommendations, and secondary outcomes included patterns of failure, toxicities. Clinical and tumor factors were reported with descriptive statistics. The cumulative risk of local failure was estimated using the Fine-Gray method, accounting for death before local failure as a competing risk. A total of 24/605 patients and 31/1412 segments within the database were treated to the posterior elements only. Local failure occurred in 11/31 segments. The cumulative rate of local recurrence was 9.7% at 12 months and 30.8% at 24 months. Amongst local failures, the most common histologies were renal cell carcinoma (36.4%) and non-small cell lung cancer (36.4%). At baseline, 4/11 (36.4%) segments with local failure (36.4%) had epidural disease and 8/11 (72.7%) had paraspinal disease. Most local failures were treated in the de novo setting (8/11, 72.7%). 6/11 (54.5%) failed exclusively within treated CTV sectors and 5/11 (45.5%) with both treated and adjacent untreated sectors. Of these five, four had disease progression within the untreated vertebral body. No failures occurred exclusively within the untreated vertebral body. One patient (4.2%) experienced a grade 4 skin toxicity and one patient (4.2%) developed an iatrogenic Grade 1 vertebral compression fracture. Posterior element alone metastases are rare. Our analyses support SBRT consensus contouring guidelines such that the vertebral body can be excluded from CTV in spinal metastases confined to the posterior elements.

The generalized IFS Bayesian method and an associated variational principle covering the classical and dynamical cases

We introduce a general IFS Bayesian method for getting posterior probabilities from prior probabilities, and also a generalized Bayes' rule, which will contemplate a dynamical, as well as a non-dynamical setting. Given a loss function , we detail the prior and posterior items, their consequences and exhibit several examples. Taking Θ as the set of parameters and Y as the set of data (which usually provides random samples), a general IFS is a measurable map , which can be interpreted as a family of maps . The main inspiration for the results we will get here comes from a paper by Zellner (with no dynamics), where Bayes' rule is related to a principle of minimization of information. We will show that our IFS Bayesian method which produces posterior probabilities (which are associated to holonomic probabilities) is related to the optimal solution of a variational principle, somehow corresponding to the pressure in Thermodynamic Formalism, and also to the principle of minimization of information in Information Theory. Among other results, we present the prior dynamical elements and we derive the corresponding posterior elements via the Ruelle operator of Thermodynamic Formalism; getting in this way a form of dynamical Bayes' rule.

Surgical treatment of congenital scoliosis

Early correction of congenital scoliosis including short fusion, while minimizing both mobility restrictions and growth impairment. Congenital scoliosis with marked deformity, proven progression, significant compensatory curves, and/or impairment of trunk balance. Furthermore, in case of compression of neural structures or pain due to secondary degeneration. No absolute contraindication. Posterior approach to the apex of the deformity. In the growing spine the periosteum should only be touched at the levels where fusion is planned. Insertion of pedicle screws adjacent to the hemivertebra. The posterior elements of the hemivertebra are removed: lamina, joint facets, pedicle, transverse process. Resection of the accessory proximal rib in the thoracic spine. Following blunt dissection at the lateral and anterior surface of the hemivertebra, the body of the hemivertebra and the adjacent discs are resected. The resulting gap is closed by compression via transpedicular instrumentation thus correcting the scoliotic deformity. In case of synostosis or contralateral bar formation, the concave side of the spine is dissected and the synostosis osteomized. Early mobilization on postoperative day1. Bracing for 12weeks depending on stability of the instrumentation. Periodic clinical and radiographic controls until the end of growth. Posterior hemivertebra resection with transpedicular instrumentation is considered as the standard treatment of congenital scoliosis. Correction rates of 60-80% are achieved. Cervical and lumbosacral hemivertebrae may require an additional anterior approach. In case of synostosis, bar formation, or rib synostosis, further corrective surgeries may be necessary during growth.

Effect of graded posterior element and ligament removal on annulus stress and segmental stability in lumbar spine stenosis: a finite element analysis study.

The study aimed to investigate the impact of posterior element and ligament removal on the maximum von Mises stress, and maximum shear stress of the eight-layer annulus for treating stenosis at the L3-L4 and L4-L5 levels in the lumbar spine. Previous studies have indicated that laminectomy alone can result in segmental instability unless fusion is performed. However, no direct correlations have been established regarding the impact of posterior and ligament removal. To address this gap, four models were developed: Model 1 represented the intact L2-L5 model, while model 2 involved a unilateral laminotomy involving the removal of a section of the L4 inferior lamina and 50% of the ligament flavum between L4 and L5. Model 3 consisted of a complete laminectomy, which included the removal of the spinous process and lamina of L4, as well as the relevant connecting ligaments between L3-L4 and L4-L5 (ligament flavum, interspinous ligament, supraspinous ligament). In the fourth model, a complete laminectomy with 50% facetectomy was conducted. This involved the same removals as in model 3, along with a 50% removal of the inferior/superior facets of L4 and a 50% removal of the facet capsular ligaments between L3-L4 and L4-L5. The results indicated a significant change in the range of motion (ROM) at the L3-L4 and L4-L5 levels during flexion and torque situations, but no significant change during extension and bending simulation. The ROM increased by 10% from model 1 and 2 to model 3, and by 20% to model 4 during flexion simulation. The maximum shear stress and maximum von-Mises stress of the annulus and nucleus at the L3-L4 levels exhibited the greatest increase during flexion. In all eight layers of the annulus, there was an observed increase in both the maximum shear stress and maximum von-Mises stress from model 1&2 to model 3 and model 4, with the highest rate of increase noted in layers 7&8. These findings suggest that graded posterior element and ligament removal have a notable impact on stress distribution and range of motion in the lumbar spine, particularly during flexion.